Lebanese University Faculty of Engineering II Final year project
Contents
1. 203 41 N The length of the lever arm is 80 cm therefore the torque required to rotate the shaft is C Fxd C 163 N m Assuming a safety factor of 2 the required found is 326 N m During backward movement the acting dominant force is only the weight of the motor Total induced torque is 209 78 N m With a safety factor of 2 it becomes 419 56 N m Therefore the design torque is 419 56 N m 6 4 2 Proposals There are several ways to set this machine in swing motion In the following different proposals are discussed with their advantages and disadvantages to end up with the best solution All these proposals respect the requirements of speed and torque discussed earlier 6 4 2 1 Linear motor The simple and easiest method to move the machine back and forth is to install a linear motor The motor must have a 40 cm stroke and has to produce a torque around 500 N m No motor with these specifications is found on the local market so the proposal is immediately dropped The study is to be oriented toward the use of a rotary motor The desired results are reached after performing mechanical and electrical reductions 6 4 2 2 Rotary motor Electrical reduction Firstly the type of motor selected has its influence Choosing an 8 pole motor is a good start before any reduction the rotation speed is around 750 rpm at 50 Hz After that an electrical reduction can be done via the VFD Generally for a good motor performance it should2. cos 0 92 50 Hz IP 55 and weighs 16 kg Figure 6 3 C E P motor for stone cutting 6 3 4 Holding bars The cutting motor with the saw are held by two identical steel C channels The forces acting on these channels are e Weight of the motor and the saw 200 N e Miscellaneous loads additional components weight 150 N e Cutting force 300 N tangent to the saw Assuming the load is equally applied on both bars load values are entered in the simulation of Solid Works software High rigidity is needed so C channels CH 100x10 are used Figures 6 4 and 6 5 show Von Mises stress distribution and the displacement the channel undergoes Model name pied U 100x10x665 von mises Study name SimulationXpress Study Plot type Static nodal stress Stress Deformation scale 2100 66 von Mises Nim 2 8144 6605 7 467 086 5 6 789 5125 6 111 938 5 54343645 4 756 790 5 4 079 216 5 3 401 642 5 2 724 068 5 2 046 494 6 1 368 920 6 691 346 6 13 772 6 a gt Yield strength 351 571 000 0 Figure 6 4 IP Code Ingress Protection Rating classifies and rates the degrees of protection provided against the intrusion of solid objects including body parts like hands and fingers dust accidental contact and water in mechanical casings and with electrical enclosures Wikipedia The first digit 5 indicates that the enclosure provides a protection against dust and the following digit 5 indicates that the equi
3. Lebanese University Faculty of Engineering l Final year project Submitted in fulfillment of the requirements for the Mechanical Engineering Degree By ANTONIOS Elie SABBAGH Elie Automatic Small Eclate Project supervisors Dr Rany RIZK Dr Ziad YAMMINE 2012 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Acknowledgments The success of any project depends largely on the encouragement and guidelines of many others We take this opportunity to express our gratitude to the people who have been instrumental in the successful completion of this project We would like to show our greatest appreciation to Dr Ziad Yammine and Dr Rany Rizk We can t say thank you enough for their tremendous support and help Without their encouragement and guidance this project would not have materialized The guidance and support received from all the members who contributed especially Mr Georges Bassila was vital for the success of the project We are grateful for their constant support and help Finally yet importantly we would like to express our heartfelt thanks to our beloved parents for their blessings our friends and classmates for their help and wishes for the successful completion of this project Acknowledgments Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Abstract This document presents a concept design of an automated small
4. e Centering is achieved by a special bolt half right threaded and half left threaded e DC motor turns the bolt making that the two rods approach or move away 5 3 Comparison hydraulic pklon for feeding Pal hinge Ee plates for I black handle COM pass red a d d mahi hand not YA qth 1 Fa F hinge Figure 5 8 centering proposal G Comparison between different proposals will be made according to the following criteria a Number of actuators b Feeding mechanism c Centering mechanism d Unloading mechanism e Splitting precision f Rigidity of the entire machine g Effect of dust and water h Maintenance required i Ease to be cleaned j Cost of manufacturing A multiplication factor will be associated to each criterion according to its importance relatively to the owner Each proposal is evaluated by giving for each criterion the following number e 1 condition achieved e O condition can be achieved with more effort e 1 condition unachieved Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate The following table shows the results See Number of actuators ee e a a a o ao ee factor 3 mamng a e a a a oo factor 4 tery a a a a aw a a EE 3 Za a o a a ia factor 4 maa oe 4 2 machine factor 2 mapang a e e 2
5. 7 1 USA e E 7 2 ele 0 k5 0 4 AA PA APAPAP AA PP 8 EE 9 Me EEN Automatic Small Eclate a AN 25 AA AA 51 MAA APA PAYAPA 51 Abstract Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate LIST OF FIGURES Figure 1 1 different types of stones cc csecccsssccccesececesececeeseeceeeceseneceseueeeseaecessaecessgeeeees 6 Figure 1 2 CONVENTION al e Te DAAN GAGA 7 Figure 2 1 equipments used in evperimente 10 Heure 3 1 simple Hlade NADAAN AA 12 Figure 3 2 mechanical multi blades system eoseessseesssenssrersseersserssserssrereserreseersseeesseee 13 Figure 3 3 hydraulic multi blades evstem 14 PUKE KIA DUIE a 15 PIGURA E EEN 18 Figure 5 1 centering proposal A 002 1 77 20 Figure 5 2 left and right pistons filled by oil are coupled by two tubes as shown main piston acts on right piston Therefore the two pistons approach by the same amount 21 Figure 5 3 centering proposal B 00 1771 esti irinen T Ein anr ia 21 Figure 5 4 centering proposal C A 22 Figure 5 5 centering Proposal E 22 Figure 5 0 centering Proposal E ee ennaa Ne EAE AE an 23 Figure 5 7 centering proposal E 23 Figure 5 8 centering proposal o 24 Figure SIE AA AA TA 26 FIN EE 29 EUO Oe aa E E E Aa aaa 29 FV GA AA E E E PAA E AA PA AUNA 30 Figure 6 3 C E P motor for stone d dg ln 30 IEN 31 UA AA AA AA NA NAA AA AGA 31 FV O aa ANA AA AA 31 SIE AA Aa 33 PE
6. clat machine after eliminating several proposals on different basis feasibility efficiency In addition the design and execution of a Swing Cutter machine which necessity appeared during the study of the project The small eclate machine already exists in manual mode The project consists of executing an automated machine that takes small stone blocks parallelepiped shaped to produce eclate stones ready to use The project starts with introducing the eclate stones then presents several ways to automate the loading splitting and cutting processes After that an elimination procedure of several proposals took place to attempt a final design simple and feasible This same course of action was adopted to design the Swing Cutter This project presents an overview of the design process for both machines from stress analysis of critical parts to the sizing of each actuator Finally hydraulic and electrical designs are presented along with the PLC ladder diagram and the PID closed loop control Abstract Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Contents ee e 1 PSS AC AA AA AA AA DE 2 AS Oe AA AA AAA 5 1 It de ee e AA AA NE 6 1 1 DoCS EE AA AA 6 1 2 Conventional Splitting machines a 6 1 3 NEN CORNED aaa ee et ne cree AA AA AA 7 2 AI AI 9 2 1 D let El KE 9 2 2 NEW EXE AAA 9 3 BIA NI E 12 3 1 PE DE IAA 12 3 2 Multi blades system
7. wong EEN 3 pF ung ES ZG TS Ka arf 05 TI EL St 1 1 Th vu x uuy 56 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate bE bl ZH ttl fl zt TT at DOAK TEER a e e Zeg aj n m pas ION Apja gH TH zy 20 SALN x uuy Ea TA E E 5 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Die D D G Da ot Wel Oort Jue TOS ap IAEE UH IL EE i N aaa 1 Sansa AE amen MPG sa eS NG ET E AOT UW4T O YIMASNYYL eS a E pues Fe F x uuy 58
8. 288e 000 148184000 4 07 3e 000 9 6608 001 8 5878 001 7 5148 001 6 440e 001 5 5678 001 4 2948 001 3 2206 001 2147 0011 1 0736 001 1 000e 030 Minimum Safety factor is 2 26 for each part Automatic Small Eclate N B This value of safety factor does not include the intermediate parts that join the main parts it will be much bigger so it takes into consideration the possibility to add equipments and parts to the chassis Chassis 19 Lebanese University Faculty of Engineering 2 Mechanical Department 5 Block centering 5 1 Centering process consist of centering the block accordingly to his dimensions length and width Noting that for height movement pressure sensor is installed at the piston inlet Introduction Automatic Small Eclate and sudden decrease in pipe pressure will give signal to the piston to move upward Centering system to be designed should be rugged enough to operate with water and dust conditions It should be designed with the minimum possible number of actuators Many proposals have been designed for the feeding centering and unloading processes in the same time in order to choose the adequate one 5 2 Proposals 5 2 1 Proposal A Blocks are fed manually on the feeding slide where gravity moves each slab to the table level Piston a positions one block on the table between the blades Pistons b and c center the block using hydraulic centering proposal show
9. its speed depending on the type of stone hardness and size The brain automation of the machine Swing Cutter 24 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate is a programmable logic controller PLC programmed in ladder logic The variable frequency drive VFD varies the frequency of the swing motor 6 5 1 Machine logic amp state diagram The machine is automated via a Delta PLC ES2 series It has 15 inputs and 5 outputs that take into account the different operation modes e g automatic maintenance and the strict safety requirements motor run motor stall overload over current Every state of the machine is resumed in a state diagram below Swing Cutter 45 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate General Functioning State Right limit ON amp saw motor ON amp right button ON amp maintenance OFF amp auto button OFF Maintenance button ON Emergency stop Right limit ON amp saw motor ON amp right button ON amp maintenance OFF amp auto button ON Emergency stop Emergency stop Auto Button OFF Maintenance Mode One Cycle Mode Maintenance Button ON Automatic Mode Auto Button ON Right limit ON amp saw motor ON amp right button ON amp maintenance OFF Right limit ON amp auto button ON amp saw motor ON amp ri
10. stone to the splitter Splitting is performed by squeezing a stone specimen between two hardened steel blades causing it to shear in two pieces along a surface between the blades Traditional splitters require work pieces to be presented as slabs of a precise thickness e g 30mm However due to the fact that clat is usually taken from waste material the thickness is not necessarily correct say 27mm instead of 30mm In order to simplify re processing of waste material into salable clat it is suggested to cut strips of 30mm regardless of thickness The strips are then split along the 30mm dimension Stones to be split are presented to machine as rectangular pieces to be split in half along height Objective of this project is to develop an automatic hydraulic splitting line for work pieces of the following dimensions H 20 30 40 50 60 mm L 100 to 250mm Thickness 20 to 60 mm prior to splitting Scope of work includes the following e Literature and competitor survey of existing splitting machines e Theoretical calculations of splitting forces required e Economic justification of proposed system e Mechanical design including the following Introduction o Cantilever press with open access Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate o Multi blade splitting system o Material preparation saw o Design of feeding magazine in which work pieces are loaded In opera
11. than the older one especially that the worker will soend his time in packing the blocks and checking the machine s functionality without any intervention in speed control Therefore machine deserves to be executed Productivity Ul LA Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 8 Safety Different measures are taken to insure the safety of the machine and its surroundings e g operator Mechanically bolted bars on the chassis are used as a final remedy to stop the swing if it goes out of control and when all electric and control safeties have failed In addition the lead screw system assures more safety since the length of the screw is limited the trajectory of the swing is also limited A ring is mounted at the end of the screw to prevent the escape of the nut Electrically the primary way for protection several measurements are applied First in the construction of the electric panel each critical electric component is connected to a different phase By this way when a phase is lost the machine stops due to a power break off on one of the components PLC VFD or the power supply Safety is also considered in case of an over current overload and overheat In case of an over current circuit breakers cut the power off the protected component The overload safety is built in the VFD it protects the swing motor if any overload occurs The protection of motors from overheat
12. thickness is done by springs Theoretically two identical springs deform the same way if the same amount of force is Figure 0 6 centering proposal E applied on each of them So the block will push the belt supports by the same amount allowing centering Due to imperfection in springs fatigue life time and other factors a pre load on springs is a must that s why pre load nuts were added In this way the springs are locked between the pre load nut and the chassis of the centering mechanism If the split block don t fall from between the belts V shaped rods can be fixed on the upper blade in a way that pushes the belts apart a few more centimeters to allow the split block to fall 5 2 6 Proposal F 7 e Linear quide with a spring R Linear guide with a sprin Linear guide with a spring z 2 Linear guide with a Ss aa 112 24 hinge hinge hinge inge 23 Fixed linear guide Figure 0 7 centering proposal F Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate It consists of a main bar horizontal that acts on two parallel bars vertical Main bar moves by a pneumatic piston When the piston retracts the two bars are away from each other and when the main piston moves forward the two bars approach 5 2 7 Proposal G e t uses the same principle of compass to handle the block e Hydraulic piston feed the block between the blades
13. 0 Hz electricity thus its speed is constant When the saw attacks the stone speedily the motor withdraws a higher current therefore the swing motor slows down its speed to a more suitable speed Vice versa when the speed of cut is slow the cutting motor uses a lower current so the speed is adjusted thus increasing the productivity The cutting motor draws a current between 1 5 Amps no load and 7 Amps rated current This range of current has to be converted to a voltage range between O and 10 volts hence creating a feedback to the VFD The figure below shows the conversion process along with the PI loop Swing Cutter 48 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate O Jan SUIMS KAO AA AAO sas NIA ma ra aces i gi eos ea acs rcs io AG PA a nG PAO ML a NA AD eos nh ass ass rel Geir a AG PRA YA ANG GAO PALAG AA ran Gs AP PO posi ean NG ANA tay casi Ta asi PO GANG aes Tio ani Ear TAGO a PALO RN PAN AAO nG F gain Set point TI Transducer Output 40 5 Amps 9 1 A gt 0 10 V frequency Scale 0 7A 0 0 875 A 0 8 75V ANAIE Defi P amp I gains PI limits input filter Vmax Fmin Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate The graph shows the voltage output of the transducer which is also the feedback of the VFD versus the current of the cutting motor The frequency scale in the VFD is s
14. 2 Mechanical Department Automatic Small Eclate 6 3 11 Unloading rods The unloading of blocks is done with respect to the minimum actuators goal The idea is to drag a rod when the saw is cutting and while the swing returns to its initial position the rod pushes the cut block off the table stainless steel axles polyamide washers Figure 6 17 Two rods are installed to include all the dimensions requested One rod is for the blocks with a height between 2cm and 4 cm and the other for 5cm to 6cm 6 3 12 Water cooling system Water cooling is indispensable in stone cutting industry This is done by a 3 8 perforated steel pipe Water is splashed on both sides of the cutting saw Swing Cutter SS Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 6 4 The actuator 6 4 1 Concept study 6 4 1 1 Velocity range As previously mentioned the material removal rate MRR for an average hardness stone is around 30 cm HP min found experimentally For design purposes a theoretical analysis is done The MRR is assumed to be 60 cm HP min for the softest stones and 15 cm HP min for the hardest The Cutting motor has a power of 2 9 kW 73 89 HP and the saw s thickness is 2 5 mm The high speed limit for cut is reached for the softest and the smallest stone so for a 2 cm height the highest speed is 467 cm min The lowest speed of cut is reached for the hardest and biggest stone so
15. 2 542 URES mm 5725e 002 5 245e 002 4771e 002 4 294e 002 3 817e 002 3 340e 002 2 5622 002 2 385e 002 1 908e 002 1431e 002 9 542e 003 4771e 003 1 0008 0 30 Model name blade Study name Simulationxpress Study Plot type Static nodal stress Stress Deformation scale 552 542 gt Yield strength 262 685 049 0 von Mises Min 2 113 218 080 0 103 784 680 0 94 351 2380 64 917 8380 75 404 488 0 66 051 092 0 56 617 696 0 47 184 3000 377509000 20 317 5020 16 884 1040 9450 706 0 17 3075 Minimum safety factor at the hinge 2 49 gt 2 gt safe Pin Diameter 30 mm length 75 mm Model name pin Study name Simulationxpress Study Plot type Static nodal Stress Stress Deformation scale 4743 45 von Mises ON 26 239 500 0 25 088 624 0 29 538 950 0 21 189 276 0 16 839 602 0 16 489 926 0 14 140 254 0 11 750 579 0 9 440 905 0 7 08 231 0 4741 556 5 2391 882 0 42 207 8 Yield strength 351 571 000 0 Model name pin dy name Simulationxpress Study Plot type Static displacement Displacement Deformation scale 4745 43 URES mm 1 581e 003 1 448e 003 1 315e 003 1166 003 1 054e 003 9 223e 004 7 9068 004 D ppel 5 27068 004 3 953e 004 2 635e 004 1 315e 004 1 000e 030 Minimum safety factor section between blade blade support 12 49 52 gt safe Blade support Length 300 mm thickness 20 mm h
16. E E aa NA NANANG NN NATAN NAAN AG 34 UA WA ANA ANA AA E AGA NAG 34 SIE APAN KANAN GA AGA AA 35 AA AA AA 36 UA O Van AGA ANAN ANG AA ANAN 36 FV AA AA AA AA APA APA 37 Se AA E 38 EVN O LO AA AA AA 38 UA E 39 Figure 6 18 Heat bending of the water pipe with a torch a 40 LIST OF FIGURES Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 1 Introduction 1 1 Types of stone Eclate stones are produced from different types of stones and in different dimensions Stones are generally classified by their hardness which is rated by Mohs scale that gives the hardness or the softness of a stone relatively to the others The Mohs scale of mineral hardness is based on the ability of one natural sample of matter to scratch another The samples of matter used by Mohs are all minerals Minerals are pure substances found in nature Rocks are made up of one or more minerals As the hardest known naturally occurring substance when the scale was designed diamonds are at the top of the scale The hardness of a material is measured against the scale by finding the hardest material that the given material can scratch and or the softest material that can scratch the given material For example if some material is scratched by apatite but not by fluorite its hardness on the Mohs scale would fall between 4 and 5 The Mohs scale is a purely ordinal scale The picture below shows different type of stones used for e
17. and components in the future The concept is to hold the shaft through the bearings housings from both ends The design is done based on C channels 80x8 assemblies The execution is done using welding and bolts Knowing that welding can cause stress concentration in the steel it has been avoided as much as possible but its use is inevitable is some places The loads are simulated with a large safety factor to avoid stress concentration in the chassis and big deformations Figure 6 14 presents the executed chassis Figure 6 14 Rough handling by operator and technicians laying inattentively heavy things on the machine Swing Cutter 37 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 6 3 10 Saw disc cover The saw disc cover has three important functions e Protect the saw s diamond edges from its surroundings and protect the surroundings from any piece that may crack from the disc e Integrate the water cooling system indispensable in stone cutting e Hold the unloading rods that discharge the cut block from the machine In addition the cover must be easily mounted and dismounted Based on these requirements the final design of the saw s cover is presented in the figures 6 15 amp 6 16 rods supports Figure 6 15 for fixation on the lower plate Figure 6 16 Refer to the next paragraph Swing Cutter 38 Lebanese University Faculty of Engineering
18. based on the critical case This occurs when cutting force and weight force have same direction thus they can be added F total P Feut 660 288 67 948 67 Newton As already mentioned the shaft is the critical component so it s designed to sustain shock Shock can occur for many different reasons high approaching speed jamming When this occurs all kinetic energy is considered to be dissipated as torque in the shaft Assuming that this energy is dissipated in 1 5 seconds the shock force can be determined Swing Cutter 32 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate The kinetic energy of the rotating saw disc at 2800 rpm is 1 a d Where J moment of inertia of the disc x m x R m mass of the disc 4 kg R radius of the disc 0 15 m 0 Angular velocity rad sec The energy needed to rotate the disc is 2 t N C gt t Where N 2800 rom C torque created by the force around the shaft F x R t time to stop 1 5 sec Equalizing Tx jsf 2am N Cat Z Sam R 2 1 N 2 1 N FeRet mx R pix N 60 t p 58 64 Newton Thus the total force acting on the shaft is 948 67 58 64 1007 31 Newton The shaft is supported by two bearings and the load is assumed to be equally divided in two points at the holding bars level This situation is sketched below in figure 6 8 Due to low speed functioning and small trip the shaft is considered statically loaded thus it s dimensio
19. blades system It consists of multiple blades chisels steel wedges and springs The chisels rest first on the rigorous surface wedges then fill the space between the blades and the main piston so that when the main piston moves downward it will act uniformly on all the blades and the block will be split accordingly Mechanical equipments will cost money and time especially the wedges to ensure the required hardness and all equipments will need constant maintenance Therefore for a small machine this system isn t the best Figure 3 2 mechanical multi blades system 3 2 2 Hydraulic multi blades system This system consists of a manifold that contains oil or grease the chisels are fixed to small pistons and each piston is related to the manifold so that all small pistons can communicate between each other Blades system Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate main piston support reducer cover fo guide opening for firs fill chisel blade Figure 3 3 hydraulic multi blades system When the main piston moves down the manifold and the small pistons move also to a limit when some small pistons touch the stone When the pressure increases in a piston the fluid will transfer this pressure to another piston and therefore a piston will move downward much then the other The manifold provides this link between the
20. ble to rotate 20 degrees from each side f support of the piston a Y blabe support ninged plate fixed support Figure 3 4 hinged blade To solve the hardness problem in the working part of the blade carbide will be fixed so that it will act on the block 3 3 2 Stress analysis All parts have been dimensioned using solid works simulation Blade Length 300 mm thickness 15 mm height 85 mm Carbide Carbon compounded with a non metal such as boron calcium or silicon or metal such as in cobalt tantalum titanium tungsten or vanadium Metal carbides are characterized by their extreme hardness and resistance to high temperatures and are used as abrasives and in cutting drilling grinding and polishing tools See also hard metal For all simulations and for safety purposes steel AISI 1020 is assumed as the material for all steel parts and steel 1035 for the blade AISI 10XX is a plain carbon steel alloyed to max 1 of Mn maximum For AISI 1020 Young modulus 2e 011 N m Yield Strength 3 516e 08 N m Density 7900 kg m For AISI 1035 Young modulus 2 05e 011 N m2 Yield Strength 2 826e 08 N m2 Density 7850 kg m3 Blades system 15 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Model name blade Study name Simulation press Study Plot type Static displacement Displacement Deformation scale 55
21. clate Figure 1 1 different types of stones 1 2 Conventional splitting machines Conventional hydraulic splitting machines available in the market are semi automatic They consist of a feeding conveyor two blades generally upper one is movable and the lower one is fixed and a hydraulic piston Process slab to be split with the desired height is conveyed to the blades by the double amount of the desired width Each time a part of the slab is split the product will be eclate from the two sides Therefore it requires to be cut to obtain the final product desired by the customer Introduction Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate This process takes time and needs more effort from the worker to achieve the work because he will have to collect the two side split block and arrange it in a chain where the block will be cut and taking into consideration the complication of managing the center of the blocks when it is being cut Figure 1 2 conventional splitter 1 3 New concept New idea was introduced by switching the two steps of the process therefore it consists of preparing blocks by cutting the slab and then split them especially that eclate is usually taken from waste material which is not always slabs Requirements The scope of our work is to design and built a small version splitting machine with automatic loading and unloading of
22. echanism is articulated For this purpose ball bearings are installed to allow to the nut and the screw to pivot during swing The screw has a 5mm pitch and 16mm diameter HIWIN product As previously mentioned at 5 Hz frequency the motor has a speed of 75 rpm Therefore the feed rate becomes 375 mm min 37 5 cm min for the slowest cut which meet the needed speed found previously 39 cm min To ensure a long life for the components protection measurements are taken Great care is needed to avoid contamination of the ball screw with dirt and abrasive particles This is achieved by using rubber bellows to completely enclose the working surfaces Relative motion is allowed between the bellows and the rotating components screw and coupling by fitting in some bearings The following picture shows the assembled actuator flange flange Swing Motor HAHA AAA A MA NA ANS WANNE Se KA NAA KA KARINA ANAN ASA The rotary motor is bolted to a flange that can rotate Similarly the nut fixed ona flange is allowed to rotate The whole system is bolted on a manufactured chassis which is also bolted to the swing s chassis no weld is used to avoid hyperstaticity 6 5 Electric design The electric panel is designed to carry out the operation of the swing cutter in different modes It has to feed the cutting motor and control the swing motor within the safety requirements The main purpose of the design is to allow the saw to auto adjust
23. ed to output the accumulated error values F gain feed forward gain is set to add the target value to the PI controller output 50 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 7 Productivity 7 1 Introduction The productivity of any machine is an important feature to measure its efficiency The production of stone slabs by the swing cutter is measured in square meters per hour m h Each cutting cycle includes 3 phases in addition of an approximated delay of 1 5 seconds between cycles 1 Safe approach the saw leaves its initial position and heads towards the slab 2 PI controlled cut the saw penetrates the stone and cuts it along its length 3 Backward jog the saw has finished the cutting and it s going back at a higher speed to its initial position Phases 1 amp 3 are common for all kinds of stones different dimensions and different hardness However the time needed to accomplish the second phase depends on the stone being cut hardness and height The highest production that can be reached is for the softest stone having the lowest height 2 cm The cutting speed is previously approximated to be around 466 cm min The productivity comes around 6 5m h Same for the lowest production that has a cutting speed of 39 cm min hardest stone and 6 cm height The productivity is 0 39M7 h 7 2 Conclusion Taking into consideration the results above the machine is faster
24. eight 60 mm Blades system 16 Lebanese University Faculty of Engineering 2 Mechanical Department von Mises Nim 2 33 455 386 0 30 667 590 0 27 879 796 0 25 092 000 0 22 304 204 0 19 516 408 0 16 728 613 0 13 940 818 0 11 153 022 0 365 226 5 5 577 431 0 Model name blade support Study name Simulationxpress Study Plot type Static nodal stress Stress Deformation scale 18852 3 1 840 2 2 789 635 8 Yield strength 351 571 000 0 Automatic Small Eclate URES mm 20866 0053 1 9126 005 1 7396 005 1 5656 003 1 3916 003 1 21 78 003 1 0436 003 8 6936 004 6 9546 004 5 216e 004 3477 0004 Model name blade support Study name Simulationzpress Study Plot type Static displacement Displacement Deformation scale 155852 3 1 7 396 004 1 0006 030 Minimum safety factor at hinge connection 10 5 52 gt safe 3 3 3 Conclusion This type of system can satisfy the requirements and the problems of the existing Eclate machine with the dimensions shown previously Blades system 17 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 4 Chassis 4 1 Design According to the specifications sheet the chassis should be designed to allow open access accessibility in three ways Therefore blade system with main piston will be cantilevered and the chassis is C shaped It will be built fr
25. et as the highest for the minimum input voltage 1 9 volts and the lowest for the maximum voltage 8 8V These frequency values are determined experimentally The adjustment of the parameters of the control loop P and F gains is called loop tuning These parameters must be set to the optimum values for the desired control response where stability is the major requirement instability in the response creates oscillations which lead to a bad cut and a dramatic decrease in machine s life PI tuning can be done by several methods manually Ziegler Nichols method PID tuning software In manual tuning K integral gain must be first set to zero so is set to maximum Then P is increased until the output oscillates When this is done P is set to approximately half of this value Next is decreased until any offset is corrected in sufficient time for the process However low will cause instability A fast PID system overshoots and stone cutting process cannot tolerate this so the loop has to be over damped by setting P lower than the half of the P set causing oscillation Feed forward control open loop is combined to the feedback close loop to improve the system performance response and stability It is not affected by the process feedback it can never cause oscillation thus F is set to a high value Swing Cutter 13 e r e P gain proportional gain is the percentage of output error gain integral gain is the time need
26. for a 6 cm height the slowest speed is 39 cm min The machine has an angular run of 22 42 The distance between the shaft and contact point of cutting on the disc is 80 cm the course is 33 2 cm Swing Cutter 40 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Consequently the angular velocity of the shaft varies between 0 08 and 0 93 rpm 6 4 1 2 Needed Torque The swing cutter is a pendulum where the initial position is the highest During cutting the saw penetrates the slab gradually Last position is the equilibrium state of the pendulum vertical where no cut forces are applied on the saw By this arrangement the machine benefits from its own weight to cut so a smaller external force is required Weight P 660 N Cutting force F 300 N Assuming the cutting is done on a linear path C trajectory Ma e ee A Projection of P in the cutting direction P x S Considering the highest position A 6 35 cm The cutting pass is considered to be a straight line but in fact it s a curve The angle between the projection of the weight force and the vertical is smaller in reality so the cosine is larger thus the norm of the projected weight force is higher which add safety to the system Swing Cutter 41 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate C 43 39 cm Py 96 59 N So the needed external force is F F P 300 96 59
27. form of a swing The concept of a swing cutter is simple and economic It s just a saw hanged on a shaft that rotates around two bearings and swings within the stone to cut it The design insures that the bearings are away from any wear and it appears very compact thus less space is needed for the machine In the following a detailed design of the swing cutter mechanical and electrical is shown respecting certain specifications According to the requested specs the eclate machine needed must be capable to take in blocks with bounded dimensions refer to so the designed swing cutter will be able to produce these working pieces The machine also respects the basic requirements of any stone cutting machine water cooling safety components 6 3 Mechanical design 6 3 1 Preprocessing sketch Figures 6 1 8 6 2 show a Preliminary sketch of the swing cutter The sketches are essential to dimension different components of the machine The saw disc used has a 30 centimeters diameter The biggest stone cut has a 25 cm length 6 cm height and 6 cm width The cut in the swing cutter has an arc trajectory A minimum distance of 5 millimeters between the cutting point on the edge of the saw and the borders of the stone must be cleared The distance between the shaft and the motor axle is found to be around 80 cm A clearance distance between the flange of the motor and the stone is verified Now that the geometry of the machine is known the app
28. ght button ON amp maintenance OFF amp auto button OFF Maintenance Button ON One Cycle Mode Right limit switch ON Saw ON amp right button ON Move Backward Move Forward Right button ON right limit switch ON amp left button ON Stop button ON Stop button ON Swing Cutter Left limit switch ON 46 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Automatic Mode Right limit switch ON Saw ON amp right button ON amp auto button ON Right limit switch ON Move Backward Move Forward right limit switch ON Right button ON amp left button ON Stop button ON Stop button ON Left limit switch ON Maintenance Mode Right limit switch ON Right button ON amp maintenance button ON Right button ON Move Backward Move Forward Right button ON left button ON Stop button ON Stop button ON Swing Cutter Left button ON 4 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 6 5 2 Pi control The auto adjustability of the cutting speed is controlled in a PI loop This is done by a VFD set into PI mode Based on the swing motor rated power the iE5 from LS industries is selected The general idea is to create a set point for the PI loop it s the current drawn by the cutting motor The motor is asynchronous and functions on 5
29. ing is also available A thermal relay protects the cutting motor when it draws current higher than the rated current for a certain period of time As for the swing motor the VFD protects it from overheating The PLC ladder diagram contains several conditions dedicated for safety For example swinging cannot begin or persist if the cutting motor is off When a fault occurs the machine shuts down immediately and a red fault light starts flashing The frequency of flashes and their numbers indicate the nature of the fault The faults can be jammed buttons jammed limit switches motor overload emergency stop button is pushed A user s manual explains each fault and its flash code Safety 52 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 9 References gt gt v VV WV WM Mechanical Engineering Design Author Joseph Edward Shigely McGraw Hill Book Company first Edition Fluid Power designers Lighting Reference Handbook The PAQUIN Company Fourth Edition Programmable Logic Controller Authors R Ackerman J Franz T Hartmann A Hopf M Kantel B Plagemann Festo Didactic KG Esslingen FAG catalogues page 147 HIWIN Catalogues ball screws SHERMEL Archives Dr Ziad Yammine http en wikipedia org wiki Mohs scale of mineral hardness gt http www businessdictionary com definition carbide html ixzz271NmSY2a References 53 Lebanese University Faculty
30. is cut out from the table figures 6 12 26 13 show the process The simulation of applied forces shows that the table is fail safe and the Figure 6 12 Figure 6 13 Swing Cutter A table with a clean straight surface not bended Bending is a inevitable phenomenon when cutting out a piece of steel from a large slab using heat 36 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Deformation that may take place is acceptable in um von Mises Nin URES mm 4 468 215 0 9 5788 005 41142520 2 Gel 3740 205 8 7 9828 005 3 366 325 5 7483 0053 29923625 E 3858 0013 2618 399 5 5 5878 0013 2244363 4 7058 0015 1 870 473 00 3 9971 2 003 1 496 509 9 3193 0053 122 546 8 2 394e 005 7455057 1 596e 005 374 6205 odel name table swivel rev1 Model name table swivel rey 7 9322004 Study name Simulation press Study 657 4 Study E SimulationXpress Study Plot type Static nodal stress Stress 1 0008 030 Deformation scale 5407 15 Yield strength 351 571 000 0 Plot type Static displacement Displacement Deformation scale 8407 19 6 3 9 Design of the chassis The chassis of any machine with moving components must be rigid Same for the swing cutter its chassis should sustain not only loads created during machine functioning and components weight but also sudden shocks that often occur and miscellaneous outside forces Chassis should also be safe enough to allow adding parts
31. lanar Therefore blade system for the new machine will be changed as follows Pre processing 11 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 3 Blades system Several web researches were done to find the most reliable rigid and efficient blade system for the machine Three types were found 3 1 Simple blades This is the simplest blade system and easy to be manufactured it is the one used in the existing machine But the two blades are perfectly parallel so this system requires an ideal block surface parallel to the blade which is not always guaranteed and these blocs are being been recuperated from waste and will not have clean surfaces Conclusion this type of system is the worst because it will need periodically a recalibration of the blades and will not satisfy uniform force Figure 3 1 simple blade 3 2 Multi blades system Many stones have rigorous faces that can t be split with single blade It needs many blades placed next to each others and each blade will go down or up depending on the surface of the block so that all small blades act on the block There are two types of multi blades system first one is built on mechanical considerations using chisels and the second is an oleo system using grease or oil Blades system 12 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 3 2 1 Mechanical multi
32. lied forces can be found and the swing cutter can be sized Swing Cutter The path of the water to the bearings is made long and difficult 28 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate sow Se e EI SC a tonge ag minimun ei claarance Figure 6 1 Figure 6 2 6 3 2 Force analysis For a decent design a good estimation of the forces acting on the system is essential Beside the weight of the parts the cutting force created during cutting is to be determined Using a dynamometer the cutting force is experimentally approximated on an existing horizontal stone cutter for the hardest and biggest stone Granite 6 cm height required in the specifications book It has been found that a force of 250N is needed to cut the slab Assuming that the cutting force is inclined from the horizontal level by 30 degrees in the Swing Cutter geometry of the machine the cutting force will be Es 250 cos 30 288 67 Newton 6 3 3 Cutting motor For stone cutting applications special asynchronous motors are used They can be recognized by their non cylindrical shape and they appear longer and flatter than the simple motors of the same power range In this project the motor used is produced by CEP Its Swing Cutter 29 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate characteristics are 2 9 kW 230 400 volts 6 6 11 4 Amps 2800 min
33. limit the dimensions of many parts of the machine This value should be approximated 2 1 Existing formula An existing clat machine functioning in the factory is used to split large rocks of rectangular section having dimensions up to 80cm x 50 cm It was the subject of a final project done by students from the mechanical engineering department Lebanese University Roumieh in 1999 According to their study and after several experiments they reached a formula that was used in the design process The equation gives the force F kg needed to split a stone except granite or material of same hardness as a function of length L cm and height H cm F 233x j 0 686 H2 050 Applying this formula on the small slabs of different dimensions the theoretical force needed to split a slab is shown in the following table ka AN aa 47 47 019 108 108 222 195 52 32 UY 309 342 450 023 023 CEET Further research on the existing splitting machines in the market gives an idea about the needed force The smallest machine that could be found was the IGLOO which is manufactured by Steinex Italy It can split rocks of 16cm x 18cm for a 20 tons force Due to the inconsistency between these results new experimental data were needed 2 2 New experiment By installing a pressure sensor and a controller on the existing small Eclate data was collected for different kind of stones of different dimensions The pre
34. n in fig 5 1 Figure 5 1 centering proposal A Block centering N O Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Chef pilon d main pis bon Figure 5 2 left and right pistons filled by oil are coupled by two tubes as shown main piston acts on right piston Therefore the two pistons approach by the same amount e When the blades split the block pistons b and c are held in place but the pressure is cut off e After the block is split the pistons reject and the split block slides on the two faces of the V shape table 5 2 2 Proposal B e Only centering mechanism differs in this proposal e Centering is done by four compasses e Each compass is a device with two geared rods that can open and close simultaneously and with the same amount e Each compass is normally closed by spring act and the two compasses are related together Figure 5 3 centering proposal B e Compasses mechanism doesn t need any actuator because it is fixed to the blade system and act with it e After splitting the blades move back as for the compasses and the two Eclate blocks are free They can slide over the table to the collect box Block centering N LA Lebanese University Faculty of Engineering 2 Mechanical Department 5 2 3 Proposal C e Each block slides on one of the plates e Centering process is achieved du
35. n t run on a frequency less than 5 Hz and not more than 80 Hz So the minimum output rpm of the motor cannot be under 75 rpm at 5 Hz Swing Cutter 42 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Il Mechanical reduction For the mechanical reduction the options are numerous In the following two approaches are presented then the best one is selected for the execution A Gears and sheaves A good way to assemble this system is to first reduce the rotation speed of the motor with a reduction gearbox followed by sheaves and belts This way the system gains elasticity Assuming that a reduction by a ratio of 2 can be done with the belt sheave assembly the reduction required from the gearbox becomes 470 This reduction can only be made with 2 gearboxes and creates a high torque thus two belts are needed to obtain a safe system It appears that the gears sheaves assembly is not reliable inefficient and requires many components thus a high cost B Lead screw Another way to activate the machine is to translate the rotary motion into a linear motion using a lead screw mechanism By choosing a low lead screw the desired low linear speed can be attained This proposal demands less components than the first one so it has a lower manufacturing cost needs minor maintenances and the components can be easily protected from wear causing agents For all the mentioned reasons the lead scre
36. ned by limiting its maximum deflection Maximum deflection for a simply supported beam with twin loads is given Fxa 2 2 Ka Ka Ymax E a 3 1 Swing Cutter a j Fe Bs Figure 6 8 33 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate With a 20 cm F force on each action point 1007 27500 N E 210 GPa steel mxd E circular section Limiting the deflection to 0 1 mm the shaft s diameter is found to be around 35 mm For additional safety and market availability the used shaft has a 40 mm diameter This shaft holds the swing moving part through the V grooved slab Figure 6 9 shows the designed shaft Figure 6 9 Figure 6 10 Swing Cutter 34 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 6 3 7 Bearings Selection To allow swinging the shaft must fit in two bearings each on one end It has been suggested as a future experiment to incline the machine in a way that allows the stone slab fed onto the machine to slide By this way feeding can be done automatically by gravity therefore the cost of an actuator can be saved For this reason it is necessary to install bearings that can sustain the radial loads studied previously and axial loads created by inclining the machine Spherical roller bearings are the choice These bearings have a tapered bore and an adapter sleeve simplifying their mou
37. nting on a cylindrical shaft They do not need to be secured on the shaft by any additional means Locknuts can be used to locate the bearings on the shaft Bearing housing provides support for the rotating shaft Lip Seal Locating Ring Housing Roller Bearing Locating Ring Lip Seal Figure 6 11 Referring to the FAG catalogues the proper components are selected Housing SNV100 L with double lip seal good protection from water and dirt Bearing 21309 E1 KLocknut H309 Sleeve DH609 Swing Cutter 35 Lebanese University Faculty of Engineering 2 Mechanical Department 6 3 8 Design of the table Automatic Small Eclate zi AA E Sil i b PT ke ke Se Ki ec L nA Aa L CH S A Dt dE o o The purpose of a table is to hold the stone slab under the saw to be cut along an adjustable width The longest block to be cut required for this project is 25 cm so the table width should be a little larger than 25 cm The market s availability narrowed the choice to a table 300 mm wide 800 mm long and 16 mm thick Since the cutting is done through an arc the saw goes under table level thus cutting it For this reason a slot along the cutting path must be opened in two steps First a smaller slot is milled on a vertical milling machine by a 6 mm depth Then using the swing cutter itself and replacing the diamond saw by a metal cutting blade the arc shaped slot
38. of Engineering 2 Mechanical Department Automatic Small Eclate Op 10 Annex Cs AA ADSE saseyd aunde Janay 1 H El z1 TI Jd 6h AQ Du Jeau GUNS 1 eet ek NIAT WA DET E aod alog E TARE ii ZW 2600 MAETI waa KUUA Thl IL v S DEI pula afaa i E E TD ii AJ Prag und ml In a MBE EW YE F E Db Oo O Akin Ian ma n TOME MOT i i EE H 1 H z aeoo Ay md gegndu H S T e Na OU pama an a fl H 1 L J HI Md SIRA OBE MATT We J SST ISNONI 1454 J IEE ETa D CIY A08E 52URGT d E E 1 Jop ag IEE lf IDE P z arya z ma z AQEE OT Gt td H d I I OT ein Eo x uuy 54 13 Lebanese University Faculty of Engineering 2 Mechanical Department Emergency button 1 tham a rek relay contact He bebine contacteur iay H Automatic Small Eclate 5 Pg FE Annex 55 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate E KR SNE EI apow od ETS o IER KE WOE ETE Sueur pF J TTS E WANI IgE we TS Dip PING IL yal 65 T Ze ad ueg Af Aq paan APIS 8 pws NY NW OH z 55 E t T ambue yL TO BK a EH deier HG Hii Paa a Sa KA EES E e pag ER IR EN He Ex EN TE ox sis LO A a Oo O D D sde L Yd z JOS H UOD H wos z ibg z ano unn z dbg uwa
39. om 2 cm 1020 steel sheets Distance between the two C shapes is determined by the main piston house dimension which is 160 mm Vertical opening between the C shapes is limited to the size of the equipments to be installed hinged blade centering mechanism feeding and ejecting processes It is 450 mm 5 j Figure 4 1 chassis Consolidations supports are added to link the two plates fortify the structure and to support the other equipments 4 2 Stress analysis Main objective is to determine the thickness of the plates and the radius of the upper and lower fillets inside the C shapes where stresses values are critical Using solid works simulation express and after several trials thickness was determined to be 2 cm with 15 cm radius for upper fillet of and 10 cm for lower fillet von Mises N m2 155 446 192 0 142 497 216 0 129 548 232 0 116 599 256 0 103 650 280 0 I 90 701 304 0 Model name bati 1 Study name SimulationXpress Study Plot type Static nodal stress Stress Deformation scale 102 655 77 752 328 0 64 803 348 0 51 854 372 0 38 905 396 0 25 956 418 0 13 007 442 0 58 464 5 Yield strength 351 571 000 0 Chassis 18 Lebanese University Faculty of Engineering 2 Mechanical Department Model name bati 1 stresss Study name SimulationXpress Study Plot type Static displacement Displacement Deformation scale 102 655 URES mmj 4
40. pistons and ensures a constant pressure on all the chisels even during the split moment Considering that the pistons surfaces are relatively small diameter 26mm and the force that should be transmitted by each piston is high 1 67tons pressure acting inside the piston can reach 310 5 bars No piston with the above specifications with 3 5 cm stroke from many suppliers mechanics has been found so the best solution was to manufacture it by installing rings around the pistons In addition it is much expensive to manufacture the manifold and the cylinders in one block Conclusion this type will cost much more than the previous multi blades system Finally accordingly to the fact that the block to be split will not have a rigorous surface there is no need for the multi blades system a hinged blade will satisfy required specifications and solves the disadvantages of the simple blade 3 3 Single hinged blade This type of system consists of two blades lower blade is fixed upper blade can move downward and upward in addition to the possibility to rotate around a hinge Blades system 14 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 3 3 1 Design Knowing that the maximum length of the block that can be split is 25 cm the length of the blade is to be 30 cm with a 15 mm thickness and 8 cm height Adding the hinge will give one more degree of freedom to the plate which will be a
41. pment inside the enclosure is protected from water jets from any direction Based on finite element method Swing Cutter 30 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Model name C channel CH 100x10 Fixture Study name SimulationXpress Study Plot type Static displacement Displacement URES mm Deformation scale 2100 66 3 280e 002 3 007e 002 2 733e 002 2 460e 002 2487e 002 1 913e 002 1 640e 002 1 367e 002 1 093e 002 Acting Forces oe 5 467e 003 2 733e 003 1 000e 030 Figure 6 5 The steel C channels have a mass of 7 25kg each 6 3 5 Plates As figure 6 6 shows two steel slabs hold fast the swing The lower slab is designed in accordance to the dimensions of the motor It holds the motor with 4 M8 Allen screws The holes are drilled in the slab larger than the screws to tolerate a future motor adjustment Upper Slab L P Bars Lower Slab welding Cutting Motor Savy Nut Hanga Figure 6 6 Figure 6 7 It may come into view in this figure an additional force not mentioned in this section this force appeared later in the study of the swinging system Swing Cutter 31 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Adjusting the motor once in a while and after every dismounting and mounting is critical it assures that the cut is done properly On the other edge of the holding bars the u
42. pper slab hangs the motor on a shaft It s a rectangular slab with a V groove Its width is dimensioned a little larger than the C channels width to allow a good weld between the slab and the channels Welding is also used to attach the lower slab to the channels Parallelism must be ensured between the plates This is done by passing the welded assembly on a mill Consequently the motor s shaft and the swing shaft become parallel The upper slab is screwed to the shaft with 5 M10 Allen screws equally distant The V shaped groove on the upper slab insures the settlement of the shaft tangent inside it In this way the shear stresses created in the screws will be smaller Further details in the next paragraph 6 3 6 The shaft In a swing cutter the critical component to be designed is the shaft The shaft is supporting the following forces e Weight of the motor and cutting disc e Weight of the C channels and the slabs e Reaction due to the cutting e Centrifugal force due to the acceleration which can be neglected due to low speed functioning The total mass of equipments hanged on the shaft is e Motor 16 kg e disc and its supports 2 kg e Cchannels 2 x 7 25 kg 14 5 kg e Steel slabs 6 5 7 3 13 8 kg e Miscellaneous weight due to weld bolts etc 20 kg Thus the total mass is estimated around 66 kg so the total weight is 66 x 10 660 Newton The cutting force is variable in direction during cutting therefore sizing will be
43. rent stones hardness a soft stone is relatively easier to cut thus a faster cut but a hard stone will need slow speeds to be cut Conventional cutters with one degree of freedom along an axis are widely used and can have different forms Some of them have a stationary cutting saw and a table holding the stones approaches the saw Some others have fixed tables supporting the stones and the Saw moves toward them These forms of cutters have a relatively good efficiency but have also some major problems For the first type of cutters a moving table needs wheels mounted on bearings When these bearings are kept unprotected from water and dirt they will be subjected to a dramatic decrease in life Generally any moving part subjected to wear must be well protected A Swing Cutter 3 Shermel Archives 27 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate good solution already applied to protect these bearings is the use of labyrinth seals they are efficient but not very cheap Some designs use rollers that move on a bar submersed in oil gutters so that rollers are always rotating in the oil And knowing that the water and the oil aren t miscible rollers can be protected from water attack The second type of cutters appears more reliable All moving parts can be installed from the above away from wear s sources On the light of these observations the stone cutter in this project will take the
44. ring the move of the blades it is pushed between the two plates coupled by a four bar mechanism e Plates are normally closed by spring force e Four bar mechanism consists of one fixed diagonal bar another one free to rotate and the bars fixed to the plates e When the plates tried to open and by the fact that they are mechanically coupled by the four bar mechanism the plates rotate equally and center the block e Unloading will be achieved when the blades retracts Automatic Small Eclate V plate fixed bar movable bar movable plate bar fixed bar movable bar movable plate bar Figure 5 4 centering proposal C 5 2 4 Proposal D Figure 5 5 centering proposal D Block centering N N Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 5 2 5 Proposal E It consists of a round table with a slot Blocks are fed vertically into the slot by the table rotation The table holds the block and rotates to put it between the blades Any of the previous centering mechanisms can be used Table can contain many slots to speed up the machine therefore while a block is being split another is put in the slot The block is pushed between the two belts from the end that forms a V shape The rotating belts carry the block between the blades and move it between the blades The centering of the block along its
45. s sssensssensseersseersseressressrrrossrrssrerssreessrresereeseersseeesseeeseeress 12 3 2 1 Mechanical multi blades svstem a 13 3 2 2 Hydraulic multi blades system 13 3 3 Single hinged plade Ia 14 3 3 1 BA KEE 15 3 3 2 SUE EU 15 3 3 3 Seine UE 17 Sa E EEN 18 4 1 WA AA AA AA AAP AA AA 18 4 2 EE 18 5 POG ge 20 5 1 WAT OCU TNO AA AA AA AA E EEA 20 5 2 POO IA EE E 20 5 2 1 POPO A II E AE EE 20 5 2 2 Proposal EE 21 5 2 3 Propo IS 22 5 2 4 Pronos RE 22 5 2 5 PODO SLE erase sc a E AA A a a 23 5 2 6 POPO SA AAA A A EEE TN IDUMU WA 23 5 2 7 POPO GE 24 5 3 IVA SON mGA ANA 24 5 4 Bien ca aNg GAAN AA 25 Abstract Lebanese University Faculty of Engineering 2 Mechanical Department 5 4 1 FINAL Jaan NAGO 6 SWINE CULLEN neo NANANAKIT 6 1 Ale 6 2 Requirements 6 3 Mechanical design wmmemeaa 6 3 1 Preprocessing Sketch 6 3 2 Force analysis 6 3 3 CUTE MOTOT nar AA NAGO 6 3 4 Holding ee 6 3 5 WE AA NAA AA AA 6 3 6 ANA AA 6 3 7 Bearings Selection 6 3 8 Design of the table 6 3 9 Design of the chassis 6 3 10 Saw disc cover 6 3 11 Unloading EE aan as 6 3 12 Water cooling system 6 4 RE E e AN AA 6 4 1 Concept UA AA 6 4 2 Proposals ARA 6 5 a aa AA 6 5 1 Machine logic amp state diagram 6 5 2 PICO Ol RE 7 PROC NA EE
46. ssure will be converted to a voltage signal in the sensor and then transformed to a pressure value in the controller Pre processing Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate Figure 2 1 equipments used in experiments For the majority of stones the longest and the highest slab 20cm x 6cm required 25 bars 1 7 tons to split and no notable differences between the biggest and the smallest block As for the granite numbers increased significantly So it has been decided to redo a more detailed experiment on granite slabs Results are shown in the table below Table 2 1 pressure results on granite stone From the experiments the maximum needed pressure to split the largest and hardest slab is 139 bars The piston s diameter is assumed to be 90 mm so its section is p2 S nG 6361 73 mm The Force needed EF PXS F O tons Relying on these results the splitter will be designed on a 15 tons basis Pre processing 10 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate N B during the experiments many types of stones especially the metamorphic one marble were half split or broken After examination of the blade two problems were found The working part of the blade has lost its sharpness and should be refined The force wasn t distributed uniformly overall the block upper and lower blades weren t neither parallel nor cop
47. this project requested the design of a material preparation saw dedicated to the eclate machine that prepares these small blocks In addition the dependency on machine operators must be reduced for a better and injury free production For all these purposes an automatic swing cutter was designed and executed Basically stone must be fed automatically in form of slabs to the machine to be cut into small blocks of desired width to be finally unloaded automatically from the machine In stone industry cutting is done by a circular diamond saw blade a diamond blade is a saw blade which has diamonds fixed on its edges for cutting hard or abrasive materials 6 2 Requirements Cutting speed is an influential factor though bounded low speeds insure a good final product at the expense of time while high speeds increase productivity but degrade the product s quality Therefore we define the expression Material Removal Rate MRR as the volume of material removed per horsepower per minute Its value is determined experimentally from existing saw machines For an average stone hardness the MRR is approximated around 30 cm HP min All design calculations for the cutter that follow in this chapter will be based on this value Principally a good design needs one actuator to sustain a fine machine functioning This actuator has to ensure a relative movement between the saw and the stone and must be able to auto adjusts its soeed for diffe
48. tion at beginning of cycle machine will present one work piece between the blades of the press wait for the compression cycle to complete and then remove the two clat halves o Stress analysis of major components o Hydraulic system requirements and design o Power requirements e Job shop drawings for execution e BOQ e Machine construction and assembly e Control panel design and PLC programming e Testing and commissioning System should be rugged and fail safe operation should not be stopped in case a work piece breaks or if dirt accumulates on the blades Therefore the machine should make the following steps Take automatically blocks from a feeder Move it between the blades and center it in length and width dimensions Split it into two Sort the split blocks relatively to an admissible length Count the number of pieces to facilitate the sale process Collect final product in a box N B Due to the fact that the machine will operate in the stone factory where it is always exposed to dust attack and water corrosion and according to the specification sheet the machine should have the minimum actuators Also moving parts bearing ball screw system should be protected Introduction Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 2 Pre processing The first step in the project is to determine the needed pressure or force to split the block which can
49. w proposal has been adopted 6 4 2 3 Adopted design Going with the lead screw mechanism appears to have several advantages e Compact this goes with the goal of obtaining a compact cutter e Simple to design e Easy to manufacture no specialized machinery is required e Smooth and low maintenance e Minimal number of parts e t can be self locking On the other hand the disadvantages of the system turn upin its efficiency Friction can be high on the threads especially if the lead of the screw is small which can wear the threads out quickly This inconvenience is solved by the ball screw actuator Low friction in ball screws gives high efficiency compared to other alternatives A ball screw can have efficiency up to 90 compared to a 50 efficiency of an ACME lead screw of the same size All this contributes in extending the lifespan of the assembly thus reducing maintenance and parts replacements and combining with the overall performance benefit of the reduced power requirements it can equalize the initial costs of using ball screws Swing Cutter 43 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate The 8 pole rotary motor is coupled to the screw with a customized aluminum coupling The coupling is designed to sustain the tensional forces created by the swing s weight component The nut is fixed on the holding bars of the machine Since the cutting movement is an arc not linear the whole m
50. water factor 3 aa a a a e o o o factor 2 par a a a a a ol factor 1 Cost of manufacturing a 3 5 1 comparison between aa According to the comparison table above proposal D is the most adequate 5 4 Final design 5 4 1 Final sketch Final sketch attempted and shown below consists of a round rotating table having four slots Each one has a function one take the block under the feeding system built vertically to ensure blocks overstock In this instant the worker can check another block in the second slot while a third block is being split The last slot is for unloading the split stones and collects them in a box 25 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate p main piston feeding system Chassis round table Figure 5 9 Eclate final sketch The continuous chain is ensured by the rotary table It can feed check split and unload the blocks in the same time Therefore time to accomplish the work will be much smaller than other systems and proposals 26 Lebanese University Faculty of Engineering 2 Mechanical Department Automatic Small Eclate 6 Swing Cutter 6 1 Object With the increase of the production capacity of eclate it is necessary to increase the production of blocks that need to be fed into the eclate machine while maintaining the lowest consumption of time and energy The specifications of
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