Design and Analysis of Lifting Tool Assemblies to Lift different Engine Block

Transcription

1 Design and Analysis of Lifting Tool Assemblies to Lift different Engine Block Arpana Sawant 1, Nilaj N. Deshmukh 1, Santosh Chauhan 1, Mandar Dabhadkar 2, Rupali Deore 2 1 Mechanical Engineering, Fr. C. Rodrigues Institute of Technology, Sector- 9A, Vashi, Navi Mumbai, India 2 Cummins India Ltd, Pune, India 1 arpanasawant51@gmail.com Abstract Engines block are required to be lifted from one place to another while they are being processed. The human effort required for this purpose is more and also the engine block may get damaged if it is not handled properly. There is a need for designing a proper lifting tool which will be able to conveniently lift the engine block and place it at the desired position without any accident and damage to the engine block. In the present study lifting tool assemblies are designed and analyzed in such way that it may lift different categories of engine blocks. The lifting tool assembly consists of lifting plate, lifting ring, cap screws and washers. A parametric model and assembly of Lifting tool is done in 3D modeling software CREO 2.0 and analysis is carried out in ANSYS Workbench A test block of weight equivalent to that of an engine block is considered for the purpose of analysis. In the preliminary study, without washer the stresses obtained on the lifting tool were more than the safety margin. In the present design, washers were used with appropriate dimensions which helps to bring down the stresses on the lifting tool within the safety margin. Analysis is carried out to verify that tool design meets the ASME BTH-1 required safety margin. Keywords- Lifting Tool, Modelling, Analysis, Load Cases, Acceptance Criteria, Stress limit and Bolt margins. INTRODUCTION A lifting operation is an operation concerned with the lifting and lowering of a load. Field service has requested that to require unique lifting tool to lift every engine family blocks, while using this lifting tool, need to change only bolt size and washer as per weight of engine block. So design of lifting tool should be as per ASME_BTH- 1(Below Hook Lifting Devices). Gaurav Bhusari and M.Sohail and Pervez 1 carried out the strength and fatigue analysis on the fixture bracket for the safety of the operator and production system.gayan Rathnaweera 2, find out the weight carrying capacity of Lifting Bracket using Finite Element Method. Sontake 3 in his study explained that the engine mounting plays an important role in reducing the noise, vibrations and harshness for improving vehicle ride comfort. The brackets on the frame that support the engine undergo high static and dynamic stresses as well as huge amount of vibrations. P.D. Jadhav and Ramakrishna 4 in their study the existing model was optimized and a novel model was proposed to reduce the weight of the rib of the engine mounting bracket.pramod Walunje and V. K. Kurkute 5 carried out analysis using that ANSYS software and found out the optimized volume of engine bracket results in saving structural weight.

2 METHODOLOGY There are engine blocks of four different types of engine family need to lift for many different operations like assembly point, manufacturing process in plant. Purpose of this work is to design and analysis of engine block of four type of engine family as 3.9/6.7 Liter, 8.3/11 Liter, ISX 12 and 15 Liter. There are four sizes of bolt are available in stock in plant. Sizes of bolt are M12, M14, M15 and M18 and analysis helps to understand which bolt size can lift engine block from four different engine family. Every time it is not possible to consider engine block while doing analysis so consider test block and as per require mass of engine block by adjusting density of block in ANSYS Workbench 16.0 Fig 1. Illustrate that lifting arrangement of engine block. It represents that two bolt should be perpendicular into hole of engine block while lifting. A. Material Use FIGURE 1. Lifting arrangement for Engine Block 4140 alloy steel material used for Lifting ring and lifting plate. Structural steel (10.9 Grade) used for all four bolt and cast iron is used for test block and Structural steel used for washer. The objective of this study is to check weight margin of engine so need to change the required density to achieve mass of test block while doing analysis maintaining the integrity of the specifications. B. Bolt preload and lifting load calculation- Bolt preload calculated using formula = P = T/ kd (1) Table No.2 Bolt Preload Lifting load: To start with analysis is performed with 1 load i.e lbs. or 1451 kg Force = Mass Acceleration (2) = = N C.Load Cases for Analysis Mass consider for analysis = 2 lifting mass

3 Bolt location in lifting tool should be as per below dimension Table No.2 Load cases D. Acceptance Criteria 1. Stress results for Lifting plate and Lifting Ring Stresses should be lower than material yield strength of 4140 Alloy steel (Hardened) i.e. 924 MPA. 2. Bolt Margins- Tensile Load Margin,Shear Load Margin,under Head Margin,Joint Slip,Thread Strip Margin greater that 1.1 Tensile load added to maximum preload when computing the factor of safety of bolt. Table No.3 Tensile failure at bolt head The bolt carries the force by shear to the adjacent connected plate where it is transferred to the plate between the bolt and the edge of the hole. Table No.4 Bolt shear Slip critical bolted connections can be designed to resist applied shear force using friction. Table No.5 Joint Slip ANALYSIS OF LIFTING TOOL Fig. 2 represent CAD model of lifting tool is designed in CREO software 2.0 and Fig. 3 illustrate that this lifting tool assembled with lifting ring, two caps crews, M16 bolt, lifting plate and test block. Test block is consider as

4 weight of engine block. Test block density need to change according to weight of engine block in ANSYS for analysis. CAD Model Lifting Tool Assembly FIGURE 2. CAD model of Lifting Tool in CREO FIGURE 3. Assembled Components Fig. 4 illustrate that exact bolt location in lifting tool assembly. Block thread depth value is used to define length of bolt hole in test block.effective thread engagement values are used to define length of bolt inside the test block. Short distance across head bolt are used to define the length between the bolts. Bolt Location FIGURE 4. Distance Measurements Load Case 1 Lifting Mass 3200 lbs Fig. 5 and Fig. 6 illustrate that to apply bolt preload value (calculated by per equation 1) and lifting force (calculated as per equation 2) in analysis and fixed support given to lower surface of test block. Apply bolt preload and lifting force Fixed support - lower surface of test block FIGURE 5.Bolt Preload and Lifting Load FIGURE 6.Fixed Support Fig. 7 and Fig. 8 illustrate that stress plot of lifting plate and lifting ring after analysis and it found that stress level of lifting plate not meeting acceptance criteria that is above yield strength of material of plate i.e. 940 Mpa.

5 Stress level on lifting plate Stress level on lifting ring FIGURE 7.Von misses stress plots: lifting plate FIGURE 8.Von misses stress plots: lifting ring Fig. 9 illustrate that stress plot of lifting ring after analysis and stress level meeting acceptance criteria. Stress level on lifting ring FIGURE 9.Von misses stress plots: lifting ring BOLT MARGIN CALCULATION 1. Axial Force = Force reaction (Z) [N] at load step 2 (From ANSYS) 2. Shear Force = (X^2 + Y^2) (Force reaction X and Y From ANSYS) 3. Tensile yield load margin= Yield load / Axial Force 4. Tensile load UTS margin = UTS load / Axial force 5. Under head bearing to yield margin= (YTS of flange contact area)/ axial force 6. Under head bearing to UTS margin= (UTS of flange contact area)/ axial force 7. Sliding margin= Shear load capacity/ Shear load Shear load capacity =0.15 Nominal bolt preload Bolt load capacity to be consider for bolt margin calculation. Table No.3 Bolt Load Capacity (10.9 Grade)

6 OBSERVATION AND NEXT STEP Von misses stress in lifting plate is not meeting as per acceptance criteria i.e. material yield strength of 924 MPA. All five bolt margins are meeting acceptance criteria i.e. greater than 1.1.So to reduce stress area need to use washer so contact area will increase. Further increase in contact area will further reduce the high stress area. FIGURE 10. CAD model of Lifting Tool with washer Analysis Procedure- 1. Analysis is carried out as Fig.9- CAD model of lifting tool with washer. 2. Engine weight should consider double for analysis as safety margin. 3. Bolt size to be taken with respect to load as per table no.2 4. Washer size taken as D = Bolt Diameter Outer Diameter of washer = 2.2 D Inner Diameter of washer = 1.1 D Thickness of washer = 0.4 D 5. Define Co-ordinate system for geometry and contact details, meshing and apply bolt preload and force on lifting ring. 6. Run the model and calculate stress on each component and force reactions. 7. Calculate bolt margins. RESULT AND DISCUSSION Analysis is carried out for load 3200 lbs. (without washer lifting tool assembly) as result stress level is higher than yield strength of material so not meeting acceptance criteria and bolt margins are greater than 1.1 So lifting tool is designed in such way that to reduce stress level for that contact area between plate and bolt should increase so washer is assembled below bolt to increase contact area. Analysis of Lifting tool carried without and with washer (a) FIGURE 11. (a) Effect without washer on plate (b) Bolt without washer (b)

7 (a) (b) FIGURE 12. (a) Effect with washer on plate (b) Bolt with washer Analysis is carried out for four load cases with respect to bolt size and washer and it is found that stress level meeting acceptance criteria and bolt margins are greater than 1.1. Figure 13 illustrate that the stress level for bolt with washer and bolt without washer for four load cases and from this graph can conclude that if contact are increases stress level decreases. FIGURE 13. Effect of washer on stress level for different four load cases CONCLUSION Stress level of four bolt sizes with washer are under acceptance criteria and bolt margin are above 1.1 for four load cases. Designed lifting tool can lift all engine family blocks i.e. Light duty, Medium duty, Heavy duty and High horse power by changing bolt size and washer with respect to weight of engine block. REFRENCES [1]Gaurav Bhusari, M.Sohail.Pervez, Design and Analysis of fixture bracket for engine assembly line,ijirst,volume 05, October [2] Gayan Rathnaweera, Dara Switchboards, Structural analysis of lifting bracket [3] Monali Deshmukh, K.R.Sontakke, Analysis and optimization of engine mounting bracket, IJSER, Volume 3, Issue 05, May [4] Prashant Kumar Srivastava1, Rajiv Gupta, Simant, Structural Weight Optimization of a Bracket Using ANSYS, International Journal of Scientific Engineering and Research, [5] Pramod Walunje and V. K. Kurkute, Optimization of Engine Mounting Bracket Using FEA, PARIPEX International journal of research,volume2,issue12, Dec [6] P.D. Jadhav, Ramakrishna, Finite Element Analysis of Engine Mount Bracket international Journal of Advancement in Engineering Technology, Management and Applied Science,Volume3,Issue09,September [7] Yong-hai W.Xiao-mei.and Feng W Topology Optimization Design of the Bracket of a Special Vehicle Based on FEA Method, Second International Conference on Computational Intelligence, Volume 10,Issue 978, 2010.