Design and Development of Tacking and Welding Fixture for Mixing Drum of 10/7 Concrete Mixer

Transcription

1 IJIRST International Journal for Innovative Research in Science & Technology Volume 3 Issue 02 July 2016 ISSN (online): Design and Development of Tacking and Welding Fixture for Mixing Drum of 10/7 Concrete Mixer Amasidha Kallappa Athani Prof. R. R. Anyapanawa M.E Student Assistant Professor Department of Mechanical Engineering Department of Mechanical Engineering A. G. Patil Institute of Technology, Solapur A. G. Patil Institute of Technology, Solapur Abstract In this paper three tacking and welding fixtures are designed for fabricating the mixing drum of 10/7 concrete mixer by using CATIA V5R16 software and all these fixtures are developed by using general purpose structural steel like HR plates, ERW pipe, MS channel, EN8Round bar etc. Stopwatch time study method is used to note down the time required to complete the fabrication of mixing drum with and without using the fixtures. The obtained results are compared and % improvement in the productivity of mixing drum due to use of fixtures is calculated. The results of circular runout of mixing drum is also compared which are note down on the mixing drum fabricated with and without using the fixtures. Keywords: Concrete mixer, Mixing Drum, Productivity, Tacking and welding fixture I. INTRODUCTION 10/7 concrete mixer is one of the most commonly used machine to prepare the concrete at faster rate. Concrete mixing drum is one of the important parts of this machine. Till today many competitors of universal are using casted mixing drum in 10/7 concrete mixer machine. Generally for manufacturing the mixing drum sand casting method is used. In casted mixing drum the gear ring used for rotating the drum is integral part of drum. The total weight of mixing drum along with 104 teeth gear ring is Kg. The top cone and bottom cone shape is conical due this complicated shape and large size the manufacturing cost of mixing drum is more. Due to this reason Universal construction machinery and equipments Ltd. has decided to replace this casted mixing drum with sheet metal mixing drum with intension to reduce its weight and cost. Universal designed completely new mixing drum in sheet metal for 10/7 concrete mixer and manufactured first sample piece in their R& D department and tested it thoroughly for its performance then they decided to regularize this mixing drum in their regular production. The mixing drum is having complicated shape and large size due to this reason it is not possible to manufacture this drum in single piece. So that the total drum is divided in to seven sheet metal parts like Bottom plate, Drum pipe, Bottom cone, Middle shell, Top cone, Discharge ring and flap. All these parts are joined together by using CO2 welding process. This project is mainly focus on design and develops the tacking and welding fixture to solve the problem of distortion and improve the productivity by reducing the production time. Mass production aims at high productivity to reduce unit cost, and interchangeability to facilitate easy assembly. This necessitates production devices to increase the rate of manufacture. Manufacture activity includes fabrication, machining, assembly and inspection etc. Production devices are generally work holders with/without tool guiding or setting arrangement. These are called Jigs and fixture. Jigs and fixture provide a means of manufacturing interchangeable parts on mass scale since they eliminate the necessity of special setup for each individual part. Once a jig or fixture is properly setup, then any number of duplicate parts may be produced without additional setup.10/7 concrete mixer mixing drums manufactured without fixture have some problems as mentioned below 1) Drum rotate with 30-35mm run out due to distortion caused by welding process. 2) Bearings used for mounting the mixing drum gates failed frequently due to run out problem. 3) About 7 to 8 hours time is required to manufacture the mixing drum by existing method i.e. without fixture. II. 3D MODELS OF WELDING FIXTURE The main task in this project is to design and develop the tacking and welding fixture for mixing drum of 10/7 concrete mixer. After detailed study of existing process of manufacturing the mixing drum in Universal without using any fixture it is decided that to design the suitable fixture for tacking and welding of mixing drum. In this project for developing the fixture models CATIA V5R16 is used. In the first stage 3D models of the welding fixture are developed in CATIA and its drafting is also done in the CATIA V5R16. These drawings are used for manufacturing the welding fixtures. Due to the large size and complicated shape of mixing drum it is not possible to manufacture the complete mixing drum in a single fixture. Therefore total three fixture are developed for simplify this fabrication task. In this chapter we will discuss the detailed construction and its use for manufacturing the mixing drum one by one. All rights reserved by 386

2 Bottom Half Part of Mixing Drum Tacking and Welding Fixture: Design and Development of Tacking and Welding Fixture for Mixing Drum of 10/7 Concrete Mixer Total three fixtures are used to fabricate the complete mixing drum in this the first fixture i.e. Bottom half part of mixing drum tacking and welding fixture is used to tack and weld the parts like Bottom plate,drum pipe, Bottom cone, Middle shell together after that internal full welding is carried out in the same fixture. In this first of all Bottom plate is placed on the base plate of this fixture and drum pipe is inserted on the fixture shaft. At the bottom side of this shaft guiding collar is fitted which correctly locate and position the drum pipe exactly at the bottom plate center and perpendicular to its surface. Drum pipe position is fixed by inserting bearing collar at the top of drum pipe. Then the middle shell is inserted in the fixture. The shell bottom side rest on the machined middle plate of fixture. Then middle shell position is fixed by clamping it at its top edge by using toggle clamp fitted on the fixture top plate. Then bottom cone is inserted in the middle shell and it is pushed in the downward direction. To push it in downward direction bottom cone pressing and holding cone is inserted on drum pipe and nut fitted on fixture shaft and it is tightened till to bottom cone touch to the surface of bottom plate firmly. After inserting each part at its proper position in the fixture they are tacked together to fix their position and finally internal full welding is done in the clamped condition. The complete bottom half part of mixing drum in the welding fixture is as shown in the figure. Fig. 1: 3D Model of tacking and welding fixture of Bottom half part of mixing drum Top half part of mixing drum tacking and welding fixture To fabricate the top half part of mixing drum second fixture is used i.e. Top half part tacking and welding fixture. In this fixture three parts are there first one is Top cone locating fixture, second one is discharge ring clamp and Nut. First of all the top cone is inserted in the top cone locator fixture with small conical portion of top cone in the upward direction. The base of top cone will rest on the bottom plate top surface in between the stopper fitted on the top surface of bottom plate of top cone locating fixture. The upper open surface of top cone will rest on the vertical surface of top cone locater plate. In this way the motion of top cone is restricted in all direction except in upward direction. Then the discharge manufactured on press machine is inserted in the top cone locator fixture above the top cone. The bottom portion of discharge ring will rest on the vertical surface of remaining half portion of top cone locator plate. In the next step the discharge ring and top cone are clamped together by using discharge ring clamp and nut. The discharge ring clamp is placed on the top surface of discharge ring and nut is tightened till to have the proper alignment of discharge ring and top cone. Finally tacking and welding is carried out in the sane fixture. The top half part of mixing drum tacking and welding fixture is as shown in the figure. All rights reserved by 387

3 Design and Development of Tacking and Welding Fixture for Mixing Drum of 10/7 Concrete Mixer Fig. 2: 3D Model of Top half part of mixing drum tacking and welding fixture Top and Bottom half part assembly and welding fixture This fixture is used to assemble and weld the top half and bottom half part of mixing drum fabricated in the first and second fixture. In this fixture first of all with the help of EOT crane the top half part of mixing drum is inserted in the fixture in inverted position. The discharge ring of the top half part of mixing drum will rest on the bottom plate in the groove. The vertical flat welded on the surface of bottom plate will locate the top half part of mixing drum. Then the readily fabricated bottom half part of mixing drum is inserted in the fixture in the inverted position with the help of EOT carne. The fixed bearing collar fitted on the pipe support plate of the fixture will locate the drum pipe of bottom half part of mixing drum. Then the movable bearing collar is inserted at the bottom of drum pipe. After completing proper locating of top half and bottom half part of mixing drum both parts are clamped together by tightening the clamp nut with the help of Tommy bar. After completing the clamping finally all external full welding is done in the same fixture. Before removing the mixing drum from the fixture it is allowed to cool down in the clamped condition. The mixing drum in the fixture is as shown in the figure Fig. 3: 3D Model of mixing drum in Top and Bottom half part assembly and welding fixture. All rights reserved by 388

4 Design and Development of Tacking and Welding Fixture for Mixing Drum of 10/7 Concrete Mixer Improvement in Productivity of Mixing Drum III. RESULT AND DISCUSSION Table 1 Time required completing the fabrication of the mixing drum without using fixture Sr. No Part Name Operation Time required to complete operation (Minute) Avg. time required (Minute) 1 Bottom half part of mixing drum Tacking Bottom half part of mixing drum Welding Top half part of mixing drum Tacking Top half part of mixing drum Welding Top and bottom half part of mixing drum Tacking Top and bottom half part of mixing drum Welding Mixing drum Finishing Total time required to complete the fabrication of mixing drum Table 2 Time required completing the fabrication of the mixing drum by using fixture Sr. No Part Name Operation Time required to complete operation (Minute) Avg. time required (Minute) 1 Bottom half part of mixing drum Tacking Bottom half part of mixing drum Welding Top half part of mixing drum Tacking Top half part of mixing drum Welding Top and bottom half part of mixing drum Tacking Top and bottom half part of mixing drum Welding Mixing drum Finishing Total time required to complete the fabrication of mixing drum Total time saved due to use of tacking and welding fixture for fabricating mixing drum = (A B) = = Minutes Percentage productivity improvement = [(A B) / A ] X 100 Percentage productivity improvement = [( ) / ] X 100 Percentage productivity improvement = Where, A= Avg. time required to fabricate the mixing drum without fixture B= Avg. time required to fabricate the mixing drum with fixture Overall % productivity is improved due to the use of tacking and welding fixture for fabricating the mixing drum of 10/7 concrete mixer. Fig. 4: Comparative results of time required to complete the fabrication of mixing drum All rights reserved by 389

5 Reduction in the Value of Circular Runout of Mixing Drum: Design and Development of Tacking and Welding Fixture for Mixing Drum of 10/7 Concrete Mixer Table 3 Circular runout of the mixing drum fabricated without fixture. Sr.No. Part Name Parameter to be measured Instrument used Observations (mm) Avg. Circular runout (mm) 1 Mixing drum Circular runout Metric tape Table 4 Circular runout of the mixing drum fabricated with fixture Sr.No. Part Name Parameter to be measured Instrument used Observations (mm) Avg. Circular runout (mm) 1 Mixing drum Circular runout Dial indicator (0-10 mm) Fig. 5: Comparative results of circular runout of mixing drum fabricated without and with fixture The avg. circular runout observed on the mixing drum fabricated without fixture is 32.33mm and on the mixing drum fabricated with fixture it is observed 3.95mm Due to the use of welding fixtures for fabricating the mixing drum of 10/7 concrete mixer the average circular runout reduced by 28.38mm IV. CONCLUSION In this project the most challenging task is design and develop the suitable tacking and welding fixtures for fabricating the mixing drum of 10/7 concrete mixer. From obtained result I would like to conclude that Total three fixtures are developed for fabricating the mixing drum namely Bottom half part of mixing tacking and welding fixture, Top half part of mixing drum tacking and welding fixture and Top and Bottom half part of mixing drum assembly and welding fixture. All these three fixtures 3D model is developed in CATIA V5R16. Stopwatch time study method is used to note down how much time is required to complete the fabrication of mixing drum with and without using fixtures. Total on an average minutes are required to complete the fabrication of mixing drum without using fixtures and only minutes are required to complete the fabrication of mixing drum by using fixtures. Due to use of newly developed fixtures for fabricating the mixing drum total minutes time is saved per mixing drum. In terms of productivity it is observed that overall 42.75% productivity is improved. Circular runout is measured by using Metric tape and Dial indicator, on an average 32.33mm circular runout is observed on mixing drum manufactured without using fixtures and it is observed only 3.95 mm on mixing drum manufactured by using fixtures. Due to use of newly developed fixtures for fabricating the mixing drum circular runout is reduced by mm. REFERENCES [1] Jigar D Suthar, K.M.Patel, and Sanjay G Luhana, Design and analysis of fixture for welding an exhaust impeller, Chemical, Civil and Mechanical Engineering Tracks of 3 rd Nirma University International Conference, 51 ( 2013 ) [2] Liu Xu, Chao Ma,Xia Xie, Design of Automobile Body Welding Fixture, International Conference on Automobile and Traffic Science, Materials, Metallurgy Engineering, Proceedings of the (2012) [3] M. Vural, H.F. Muzafferoglu, U.C. Tapici, The effect of welding fixtures on welding distortions, Journal of Achievements in Materials and Manufacturing Engineering, vol.20 Issues 1-2 (2007) All rights reserved by 390