Design and Manufacturing of 3-stage PLC based Equipment for Oil Sump Sub-assembly

Transcription

1 Design and Manufacturing of 3-stage PLC based Equipment for Oil Sump Sub-assembly S Chaudhari & S Kulkarni Sinhgad College of Engineering, Pune University, India sgchaudhari123@gmail.com Abstract In recent years, low cost automation has become essential requirement in the field of Manufacturing. The low cost automation using pneumatic, hydraulics and PLC was done to perform assembling of an Eagle Oil Sump. Step by step execution of the assembly operations was ensured and successfully implemented by making three assembling equipments. Keywords Low cost automation, PLC. I. INTRODUCTION Automation plays an increasing important role in the global economy. The current market share of automation is more than 60 percent globally. The current envision by specialized automation engineers is referred to as PLC, is frequently used to synchronize the flow of input from sensors and input from events with the flow of output to actuators and events. The control action is to simple, user friendly, menu driven ladder software. No physical wiring is required for timer, counters, switches etc, all these components are software based. The Eagle oil sump comes as a casting from the foundry The initial machining is carried out by the vendors. The casting is not possible to be directly on the assembly line of the engine as some of the features are required to be ensured e.g. drain plug is properly tight in place. The holes require to put together two half s are required to be clear and through, etc. These are some of the features which when found missing the oil sump casting is required to be put out of assembly line. The features are not so hard to be ensured with a machine tool. The special purpose machine tools prove to be very expensive for this task. Therefore a small, dedicated, equipment was an order from Mahindra and Mahindra to Jain Industries where the Mahindra machines are assembled. The three main tasks are required to be ensured and which are ensured through the equipment properly. The present work undertaken is to device a equipment so that the clear through holes, drain pipe, drain plug are ensured proper before the oil sump goes to engine assembly line. The equipment is of three stages such that the stage one gives a all clear signal then only stage two start and accordingly later stage three starts. The total inputs and outputs are optimized so that the cost and programming burden shall be minimized. The design of the stage is not based on machine design principles but only to cater the function need. Hence it is not discussed so deep. The brief over view of the operations, the stations are described to the extent of sufficiency. II. PRODUCT PROFILE The figure 3.1 shows dimensional details of oil sump assembly. It shows different views of oil sump assembly with its dimensions such as the top view, the front view, and the back view. Two isometric drawing of oil sump are shown on uppermost left of figure. Certain minor dimensional details of the drawing are shown on the left and right side of the drawing. Figure 3.1 Dimensional details of oil sump assembly 39

2 The drain plug is fitted as shown in figure 3.2 and is present just opposite to the inclined surface on the doomed shape. The welch plug is kept oriented at 1.5mm depth inside the oil sump and is present on its little flat area. The nozzle is located on the inclined surface of the bottom as shown in figure 3.2 Figure 3.2 Oil sump assembly with different components III ACTION PLANNED The actions were performed at three different stations such as A, B, C taking care that rotating of job is done by the operator manually during the time of loading and unloading. Each station is designed accordingly so that job gets loaded on each station only after proper orientation is achieved. It is simple for the operator to perform orientation operation manually before loading the job to any stations. Every station has certain inputs and outputs. Stations A, B, C includes following operations Station A checking of clear through holes and fitting the strainer pipe Station B checking of clear through holes and drain plug fitting on oil sump. Station C orienting the welch plug in front of tool to receive 200kg pressure and nozzle fitment. The station A has inputs as optical sense for bin1, optical sense for bin2, pipe presence sense, air leak tests (pressure sense), job pressure sense, torque wrench, pneumatic pressure, torque wrench parking sense, cycle starts push button two hands. The station A has outputs as clamp/unclamp s1, air on check pipe leak s2, station A OK lamp. The station A involves checking of various parameters such as clear through holes of 10 mm diameter, presence of 2 O rings on strainer pipe and tightening of 2 strainer pipe screws at 25 Nm. The station B has inputs as job presence sense 1, job presence sense 2, optical sense for bottle, washer presence sense, torque wrench, torque wrench parking, cycle starts push button, welch plug parking. The station B has outputs as clamp/unclamp s4, station B OK lamp. The station B involves checking of various parameters such as applying loctite on periphery of drain plug, tightening of drain plug at 25 Nm using copper washer. The station C has inputs as job presence sense 1, job presence sense 2, optical sense for bin 1, optical sense for bin 2, washer presence sense, optical sense for bottle 1, optical sense for bottle 2, air leak test (pressure sense), welch plug parking, strainer pipe check, pressing tool home sense, pressing tool low lubrication sense, cycle starts push button, individual reset, master reset, em. OFF. The station C has outputs as rapid s10, power s11, station C OK lamp. The station C involves checking of various parameters such as applying of loctite on welch plug and nozzle, placing of welch plug at 1.5 mm depth inside the oil sump using 200 kg pressure, tightening of nozzle washer at 25 Nm. IV. STRAINER PIPE ASSEMBLY-STATION A The operations are divided in three stations. The station A deals with checking the O-ring presence and testing for desired pressure. Simultaneously, the required clear through holes are also ensured to avoid the rejection in the engine assembly plant. In all five significant inputs and four outputs are configured to ensure all the operations desired on the station A are successfully accomplished. The station A consists of base structure to enable the mounting and holding of the oil sump assembly, dowel pin stands to ensure clear through holes, O ring check fixture to test the presence and working pressure of O-rings, sando weight balancer, torque wrench assembly, and general operator instruction display. Construction The station A is designed and manufactured mainly based on function. The stress calculations are really not required as the design is over safe but dimensions can not be optimized as the oil sump assembly is significant 40

3 in dimensions and should be handled carefully. The base structure, dowel pin stands, O ring check fixture and sando weight balancer are the main components. INPUT/OUTPUT SPECIFICATIONS The inputs for station A are optical sensor of bin1, optical sensor of bin2, strainer pipe presence sensor, air leak tests sensor / pressure sensor, job presence sensor, torque wrench, pneumatic pressure switch, torque wrench parking sensor, cycle starts push button. The outputs at station A are clamp/unclamp s1, air on check pipe leak s2, station A OK lamp. Name Model Sensing Method Sensing Distance Size Supply Voltage Output Type Max. Current Table 1 The specifications of sensors used at station A Optical sensor E3FN-P18KPR3T- WP-BL Diffuse-reflective 300 mm M18 Cylindrical shape 10 to 30 VDC PNP or NPN Presence sensor E2A- S08KS02- WP-B1 Inductive type 2 mm -10% to +10% M8 Cylindrical shape 12 to 24 VDC Ripple10% Max. PNP open collector Pressur e sensor E2GN- M18KS 05- WS-B1 Inductiv e type 5 mm ±20% M18 Cylindri cal shape 12 to 24 VDC Ripple 10% Max PNP open collecto r 20 Ma 20 ma 20 ma ALGORITHM OF OPERATIONS The algorithm of checking the strainer pipe on the O ring check fixture is explained as below The operator places the strainer pipe over O ring check fixture. The strainer pipe presence is sensed. The input ix0.2 proxy becomes high. The O ring check cycle starts. The pressurized air is passed to fixture and it makes output QX0.1 high. The back pressure is built up in fixture when there are 2 O rings without defects then the pressure check switch gets high i.e. ix0.3=1 The switch off output QX0.1 and PLC soft timer starts. The pressure switch input ix0.3 should remain high for next 3 seconds. Fault is declared when input ix0.3 becomes low. Fault occurs due to some defects in O rings (shape, size or number). The stainer pipe is removed from the fixture when input remains stable and loaded on oil sump. The algorithm of tightening the screw over the sump is explained as below The screw is picked from bin 2. The input ix0.1 becomes momentarily high. The operator puts the screw into the oil sump and tightens the screw with the help of torque wrench. The action should be finished within 15 seconds from pick of screw from bin2. The input ix0.5 becomes high. CHECKING OF CLEAR THROUGH HOLES The figure 4.1 shows the checking of clear through holes on oil sump assembly. The operator loads oil sump at station A. The loading means placing and locating the oil sump on fixture enabled with dowel stands of station A. All six (i.e. four on sides and two below) pins in the fixture ensure that the holes are present on oil sump. The foul proofing pad on fixture ensures correct loading of oil sump by job presence sensors and ensure it. The oil sump is pneumatically clamped using 5/2 way directional control valve with single solenoid by pressing the cycle start switch which is required to be operated by two hands. The presence of oil sump is confirmed by a proximity sensor. The O ring check cycle is executed next. 41

4 The strainer pipe is lifted with O ring from bin 1 and placed inside the O ring check fixture. When the strainer pipe is sensed inside fixture, the pressurized air is passed to the fixture for checking the presence of both O rings. The pressure check switch goes low after 3 seconds if there is defect in O rings. The signal is sent to PLC that the O ring are defective. The back pressurized air continues to flow from strainer pipe netted blower head even after three seconds. It is sensed by palm of hand and is found to be stable. The strainer pipe is then removed from the fixture and loaded on oil sump. The strainer pipe tightening is executed next. Figure 4.1 Checking of clear through holes THE O-RING CHECK FIXTURE Figure 4.2 shows O ring check fixture which is designed to check the presence of two O rings on the strainer pipe. The protective pad labeled as PX03 in the figure 4.2 is used to protect the sensor s cables. It also protects the fixture from any damage which may occur during loading and unloading of oil sump on the equipment. TIGHTENING OF STRAINER PIPE Figure 4.3 shows the provision of tightening strainer pipe using two screws present inside the bin. The screws are tightened by using a torque wrench. The torque wrench is parked at its parking position which is on sando weight balancer as seen from figure 4.3. The instructions for operator are displayed just above the bin 2 for smooth operations. The OK lamp gets ON when unclamping operation is finished. The strainer pipe is inserted into oil Figure 4.2 The O ring fixture Figure 4.3 The tightening of strainer pipe 42

5 sump. The screw is lifted from the bin 2. The screw is tightened on the strainer pipe with the help of torque wrench at 25 Nm torque. Similarly another screw is taken from the bin 2 and the same operation is performed. The torque wrench signal is then given to PLC indicating that the tightening of strainer pipe by both the screws is finished. The oil sump is unclamped only after receiving the signal OK i.e. lamp is ON, from torque wrench. The operator unloads the oil sump from station A. SEQUENCE OF OPERATION The job is loaded on fixture and four pins are located. The cycle start switched is pressed. The strainer pipe is lifted. The lifted strainer pipe is placed in check fixture. The strainer pipe is removed from fixture & inserted in oil sump. One more screw (M10) is picked from bin1 The screw is started in oil sump. The torque plug is picked from parking position & inserted into the torque wrench. The screw (M10) is torque at 25 Nm torque. One more screw from bin is picked. The screw is inserted into the oil sump. The screw (M10) is torqued at 25 Nm torque. The torque plug is removed from torque wrench and placed back at its parking position & torque wrench is released. The cycle start switch is pressed. Unload the job from station A an move it to station B. V. DRAIN PLUG ASSEMBLY-STATION B INTRODUCTION The station B deals with checking 15 clear through holes. Simultaneously, the required clear through holes are also ensured to avoid the rejection in the engine assembly plant. In all eight significant inputs and two outputs are configured to ensure all the operations desired on the station B are successfully accomplished. The station B consists of base structure to enable the mounting and holding of the oil sump assembly, vertical fixture, sando weight balancer, torque wrench assembly, and general operator instruction display. CONSTRUCTION The station B is designed and manufactured mainly based on function. The stress calculations are really not required as the design is over safe but dimensions cannot be optimized as the oil sump assembly is significant in dimensions and should be handled carefully. The base structure, vertical fixture, Sando weight balancer, torque wrench, operator instruction display, 4 different sensors, OK lamp and two cycle start switches are main components. INPUT/OUTPUT SPECIFICATIONS The inputs at station B are job presence sensor 1, job presence sensor 2, optical sensor for bottle, washer presence sensor, torque plug sensor, torque wrench parking sensor, cycle starts push button, welch plug parking sensor. The outputs at station B are clamp/unclamp s4, station B OK lamp. ALGORITHM OF OPERATION The algorithm of putting washer on drain plug and applying loctite is explained as below The drain plug screw is picked from bin 1. Input ix6.5becomes momentarily ON. The washer is picked from Bin 2. Input ix4.2 becomes momentarily ON. The washer is inserted over drain plug screw. The loctite bottle is picked from parking area. Input ix6.2 goes OFF. The loctite is applied on periphery of drain plug screw having washer and bottle is placed at parking area within 15 seconds if not alarm is ON. The algorithm of checking the presence of washer is explained as below The washer check plug is picked from parking position i.e. ix6.1 goes OFF. The operator places washer check plug over the drain plug screw head. The washer check plug checks the washer. The input ix6.3 becomes high when the washer is present. 43

6 The input ix6.3 becomes low when the washer is absent. The alarm is ON when the washer is absent for more than five seconds. The washer check plug fixture is placed back to its parking position. Input ix6.1 becomes high. LOADING THE OIL SUMP ON VERTICAL FIXTURE Figure 5.1 shows loading the oil sump on vertical fixture. The operator loads oil sump on vertical fixture at station B just unloaded from station A. The orientation of the job is done manually by the operator. The clear through holes is checked by 15 pins present on vertical fixture. A sensor senses the job. The job is clamped by using pneumatic clamps. The pneumatic clamps are activated by pressing the two cycle start button switch. CONSTRUCTION The station C is designed and manufactured mainly based on function. The stress calculations are really not required as the design is over safe but dimensions can not be optimized as the oil sump assembly is significant in dimensions and should be handled carefully. The base structure, vertical fixture, Britts hydro pneumatic cylinder, Sando weight balancer are the main components PRESENCE OF STRAINER PIPE ON OIL SUMP ASSEMBLY Figure 6.1 shows presence of strainer pipe on oil sump assembly. The job which is just unloaded from the station B is loaded on vertical fixture of the station C. The job presence is checked by proximity sensor. The strainer pipe presence is also checked by another proximity sensor. The cycle starts switch is pressed by both hands. The oil sump is pneumatically clamped and the solenoid remains ON till the end of the cycle. Figure 5.1 Loading of oil sump on vertical fixture VI. WELCH PLUG AND NOZZLE ASSEMBLY- STATION C INTRODUCTION The station C checks and ensures strainer pipe presence and fitting of welch plug and nozzle. In all significant fourteen inputs and three outputs are configured to ensure all the operations desired on the station C are successfully accomplished. The station C consists of base structure to enable the mounting and holding of the oil sump, vertical fixture, britts hydro pneumatic cylinder, sando weight balancer, torque wrench, operator instruction display, four different sensors, OK lamp, three bins and two cycle start switches. Figure 6.1 Presence of Strainer pipe on oil sump assembly FITTING OF WELCH PLUG AND NOZZLE Figure 6.2 shows fitting of welch plug and nozzle on oil sump assembly. The welch plug is taken from bin 1. The loctite bottle is picked. The loctite from bottle is applied on outer periphery of the welch plug. The loctite bottle is placed back to its parking position. The work should be finished within fifteen seconds otherwise alarm is ON. 44

7 The welch plug is loaded on britts hydro pneumatic pressing tool. The operator keeps the tool cycle start switch in pressed condition using both hands till end of operation. The solenoid valve on the hydro pneumatic cylinder for rapid stroke is made ON. The solenoid valve on the hydro Figure 6.2 Fitting of Welch Plug and Nozzle pneumatic cylinder for power stroke is made ON after three seconds. The power stroke delivers two hundred kg of force to press the welch plug into the oil sump. The pressing operation is finished. The rapid stroke and power stroke solenoid valves are made OFF. The hydro pneumatic cylinder is retracted back. The hydro pneumatic cylinder goes back to its home position. The operator releases both hand from the tool cycle start switch. The nozzle and the washer is picked from bin 2 and bin 3 (blue colour) respectively. The washer is placed over the nozzle. The red coloured loctite bottle is picked from its parking position. The loctite is applied on nozzle from bottle. The loctite bottle is placed back at its parking position within fifteen seconds otherwise alarm is ON. The nozzle is inserted in the oil sump. The nozzle is tightened using torque wrench at 25 Nm torque. The washer check plug is taken from its parking position. The washer check plug is placed over the nozzle. An alarm is ON when the washer is found absent for more than five seconds, otherwise alarm is OFF. The washer check plug is placed back to its parking position. The job is unclamped when solenoid is made OFF. Ok lamp becomes ON. The operator unloads the job. It resets all the Stations OK lamps. The operational sequence is repeated form the station A with a new job. VII. CONCLUSION The Eagle oil sump sub-assembly process was completed in all respect within 13 minutes. All the sub-components were ensured, fixed in place which otherwise would halt the engine assembly line. Less skilled labour is just enough. The automation system based on PLC is beneficial mainly due to pilot running i.e.a PLC programmed circuit can be pre-run and evaluated in the office or lab. This being the PLC operated system the sequence can be changed with little change in program and few more operations can be appended with no significant installation cost. The proficiency is maximum for such simple and significant operations. The PLC programming design and manufacturing experience with hard taught essence of assembly was the great achievement of this dissertation work. VIII. REFERENCES [1] Lance Benn, Bruce Burton, James Ireland, Sen Wang, Ron Harley, Model Gantry Crane with Dynamic Feedback Swing Control, IEEE, [2] Denni Kurniawan, Riza Sulaiman, Design and Implementation of Visual inspection system in Automatic Bottling System based on PLC, Second Asia International Conference on Modelling & Simulation, Second Asia International Conference on Modelling & Simulation, [3] Hongtao Ma, Xiaojun Wang, FenPing Zhou, Measuring and Controlling of Analog signal Based on High-speed I/O port of PLC, International Conference on Measuring Technology and Mechatronics Automation, [4] YAN Dong, QIN Bin, Advanced Control Technology Development of Sulphuric Acid connecting system based on Fuzzy control, International Conference on Intelligent System Design and Engineering Application, [5] Amir Firoozshahi, Li Mengyang, Water Treatment Plant Intelligent Monitoring in large 45

8 gas refinery, IEEE Region 8 SIBIRCON, Irkutsk Listvyanka, July 11-15, [6] Amir Firoozshahi, Intelligent Monitoring of Water Treatment Plant in Large Gas Refinery, 52nd International Symposium ELMAR, [7] Joby Antony, Basanta Mahato, Sachin Sharma, Gaurav Chitranshi, A web PLC using distributed web servers for data acquisition and control, IEEE,