Design and Manufacturing of Indexing Fixture For Piston Compressor Block

Transcription

1 Design and Manufacturing of Indexing Fixture For Piston Compressor Block Prof. G.E. Kondhalkar 1, Ganesh Kale 2, Aditya Kamble 3, Kunal Kshirsagar 4, Sarang Upasani 5 1 HOD Mechanical Dept, Anantrao Pawar College of Engineering and Research 2, 3,4,5 U.G. Students, Mechanical Dept., Anantrao Pawar College of Engineering and Research Abstract: Indexing fixture is used when a heavy component needs to be rotated for the purpose of assembly or machine work. It allows the self centered rotation of the component allowing the comfort to operator performing operations. The paper focuses on design and analysis of indexing fixture by analytical method. For this the weight of the component (in this case piston cylinder block) is used to determine stresses developed in the fixture. Modeling of the fixture is done using CATIA- V5 and ANSYS. Keywords: Analysis in ANSYS, CATIA Modeling, Indexing Fixture, Speed reduction. I. INTRODUCTION Fixture is a tool used specially to hold a work piece to perform machining operations on it. The position of the component should be fixed while machining if not errors in dimensions or unnecessary tapers size reduction may occur. Frequent checking, non-uniform quality of product, manual errors, time required for machining can be reduced by use of proper fixture assembly. Fixture design plays an important role in setup planning phase. Proper design of a fixture is crucial for developing product quality in different terms of accuracy, surface finish and precision of the machined parts. The fixture that is currently being used is very bulky. The fixture consumes that much space due to the use of bevel gear for torque transmission. Three stages of bevel gears are needed to reduce the speed from motor to fixture assembly. Also the current fixture shifts the center of compressor block from fixture. In this paper a fixture for piston compressor block will be designed using indexing fixture. To make the size of the fixture compact planetary gear mechanism is used for speed reduction. The main function of this fixture is to allow self-centered rotation of the compressor block without the operator moving around the block. Indexing fixture is rotated with the help of planetary gear mechanism. It consists of mainly three components a sun gear, a planet gear and an internally teethed gear ring. Planet gear is meshed between sun and ring gear which allows speed reduction in less space and less number of stages the normal gear boxes with spur and helical gears. The fixture should sustain the weight of the compressor block (3ton to 4ton). II. OBJECTIVE The main objective is to reduce the assembly time and increase worker efficiency. To increase accuracy and minimize space required for the old fixture. Increase the safety of worker by reducing traveling of heavy jobs. DOI: /IJRTER HUIBO 35

2 III. PROBLEM STATEMENT To design and manufacture an Indexing fixture for piston compressor block which will be rotated by 90 0 without changing its center of rotation. IV. DESIGN METHODOLOGY 1.1 Surveying and study of speed reduction methods This includes the survey of previously done research work related to use of different mechanism for speed reduction process. Use of different mechanism depending on working space conditions needs and requirements. 1.2 Selection of mechanism According to our project requirement suitable mechanism i.e. planetary gear mechanism is selected. This selection is done on the constraint of space available. 1.3 Calculation for gear box and fixture Gear teeth, diameter, addendum, dedendum, tooth thickness, face width etc. all the gear parameters are calculated. Number of stages required is also selected according calculated reduction ratio. Dimensions of fixture assembly are calculated. 1.4 Design of gear box Drawing of gear box, shafts, fixture assembly is done using suitable modeling software (CATIA) according to previously calculated values. Parts drawn are further assembled and total assembly is done. 1.5 Analysis and validation of mechanism Stress and strain analysis of the parts drawn before will be done using analysis software. Changes will be made in the designed parts for stress concentrations and other factors depending upon analysis results. 1.6 Optimization of mechanism Casing for gear box will be designed in the given space and the components of the gear box are arranged in available space and required factor of safety. IV. DESIGN OF GEARBOX COMMENCEMENT 5.1 Transmission Unit For power and speed transmission Bonfiglioli motor having planetary gear box is used. These motors have high reduction ratio because of the use of planetary gear mechanism. Fig. 1: Bonfigloli motor with gear box The motor shaft output is connected with helical gear assembly which transmits motion to the fixture at required speed which is 4 All Rights Reserved 36

3 5.2 Gear Assembly The output shaft of the motor is connected to helical gear assembly which transmits motion to fixture assembly. Gear pair is designed considering space as criteria. Gear pair calculation: Torque required to rotate the ring gear assembly: Ʈ= Ff * r1 Frictional losses between ring gear assembly and rollers (4 nos.) is considered as 19% Ff = W * 1.19 Ff = 4200 * 1.19 Ff = 5000 kg Ʈ = 5000 * 164 Ʈ = kg-mm Ʈ = 8200 N-m Speed Calculations: N ring r 1 = N 1 4 = 164 N N1 = 16 rpm Ʈ ip = N ring Ʈ op N = 16 Ʈ op 4 r ring Ʈop = 2050 N-m Power = 2πNƮ 60 Power = 2π Power = kw The power transmitted is 5.5 kw at pinion speed of 16 rpm. Diameter of pinion = Dp = 328 mm Module = 6mm Dp = Z p Module 328 = Cos α Z p 6 Zp = Zp = 52 teeth No. of teeth on pinion = Zp = 52 mm The Rounded of teeth diameter of pinion Dp = 52 6 Dp = mm Diameter of Gear = Dg = 1312mm Dg = Z p Module Cos α 1312= Z g 6 Zg = All Rights Reserved 37

4 Zg = 209 teeth The Rounded of teeth diameter of gear Dg = Dg = mm Centre Distance = D p+d g 2 Centre Distance = Centre Distance = International Journal of Recent Trends in Engineering & Research (IJRTER) 5.3 Fixture modeling For part modeling and assembly we have used CATIA V5R20. The helical gear pair is designed using standard empirical relations. CAD models of the important parts in the assembly are as follows. Fig. 2 Base Plate The compressor block is mounted on the base plate. Base plate is fixed on the ring gear and the supports of ring gear. Material used for manufacturing of the base plate is Cast Iron (C45). Fig. 3 Ring Gear and Support The ring gear and support is mounted on rollers. The rollers provide necessary uplift and stability during operation. This body is manufactured by casting and then hobbing. Fig. 4 All Rights Reserved 38

5 Rollers serve as guiding mechanism and load distribution during thrust loading and rotary motion. Rollers are mainly installed for providing external support ring assembly. Fig. 5 Indexing fixture The above image shows the full assembly of the fixture. Assembly contains standard size bolts, rollers for motion guidance and sensors for workers safety as well as for smooth working when loaded with the compressor block. V. CONCLUSION The fixture was designed for a particular application and to reduce the space required by the old fixture. Also to allow self centered rotation of the piston compressor block without any slippage. All the above problems are accomplished with this design and it is currently being implemented in the industry. The space reduction from old fixture to this new fixture is of 50%. Extra breaking system is implemented to avoid injuries to the worker and reverse rotation of the ring gear and supports. REFERENCES I. S.B.Nandeppagoudar, S.N.Shaikh1, S.H.Gawande, Optimization of Planetary Gear Box for High reduction ratio, IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-issn: ,p-ISSN: II. J.Stefanović-Marinović, Load Allocation and Equilibrium for Planetary Gear Reducers of Earth-Pressure- Balance Shield Machine, Journal of Mechanics Engineering and Automation, 2,2012, III. Syed Ibrahim Dilawer, Md. Abdul Raheem Junaidi, Dr.S.Nawazish Mehdi, Design, Load Analysis and Optimization of Compound Epicyclic Gear Trains, American Journal of Engineering Research (AJER) e-issn : p-issn : Volume-02, Issue-10, pp IV. B.Venkatesh, V.Kamala, A.M.K.Prasad, Design, Modelling and Manufacturing of Helical Gear, International Journal of Applied Engineering Research, Dindigul, Volume 1, ISSN V. Dr. P. C. Sharma, Dr. D. K. Aggarwal, Machine Design (S. K. Kataria &sons, All Rights Reserved 39