Problem StatementMy task was to develop a device that rotatedthe cap at a very low rpm.
Optimum speed of rotation required was 3 rpm. Thecaps were circular and roughening process needed a device that will hold thecap and rotate it continuously at very low rpm of 3 so that roughening toolwill roughen it uniformly. Therewere a few devices available in the market which would run at 3 rpm, but werevery costly. My aim was to develop such a device that was cost effective. C.
E 2.3.2Initial working thoughtsThe project would involve an electric motor as a basic drivingelement. Usual motors available in the market rotate at 1440 rpm.
One such motorof ‘Bharat Bijlee Ltd.’ was available in spare with us. To achieve a reductionto 3 rpm, I thought of frequency controlled drives which was a simple option.However, using such drives again would prove costly. The company wanted a muchcheaper alternative, as this was one of many operations involved and it was notworth spending more amounts on this development. High spending on this wouldadd to final cost of filter that would increase selling price of filter. Filtermarket is very competitive having cut throat competition and therefore costreduction becomes essential.
Hence, I did not go ahead with frequencycontrolled drives. C.E 2.3.3Principle of WorkingAfter some study, I decided that the bestoption to reduce the rpm was using a motor rotating at 1440 rpm with a suitablespeed reduction unit to rotate job at 3 rpm.
Upon search in local market, Ifound that ready made local make reduction gear boxes were available in themarket. These gear boxes offered gear ratios of 1:40, 1:60 and 1:80. I wantedto achieve reduction to 3 rpm from 1440 rpm. Therefore, speed was to be reducedby 1/480.
Reduction gear box with 1:80 was offering the highest reduction. Withgiven size of gear box, the teeth pitch in gear box reduces with an increase inspeed reduction and its load bearing capacity reduces. Upon further study, Ifound that reduction gear box of 1:60 would be an optimum choice. Therefore, Iprocured a local made gear box with gear ratio of 1:60.
This ensured that therpm was reduced to 1440/60 that is 24 rpm. However to achieve a rpm of 3, an additionalspeed reduction of 1/8 was essential. I thought of using another reduction gearbox, but this solution was not suitable this time. I started thinking differentoptions and one option which came to my mind was ‘use of pulleys’.
This speedreduction could be achieved through incorporating pulleys. Upon survey inmarket, I found that V pulleys of diameters 2.5″ and 20″ were readilyavailable. Three different V belts are available – “A” section V belt, “B”section V belt and “C” section V belt.
For the kind of prevailing load, “B”section V belt was the most appropriate. Using pulleys of diameter 2.5″ and20”, I could further reduce the rpm by 1/8. In turn the desired rpm of 3 couldbe achieved. This solution was discussed with the plant manager and theowner of the company and they were impressed with the solution suggested. C.E 2.
3.4AssemblyComponents to be Assembled:1. Electric motor2. Pulleys3. V belt4. Reduction Gear BoxI did the entire assembly by myself taking theentire responsibility of the project.
Speed reduction system could be obtainedby first reducing speed to 1/8 by using pulley. 1440 rpm of motor was hencereduced to 180 rpm by pulley. With an input of 180 rpm to reduction gear box of1:60, output of 3 rpm could be achieved. Motor was fixed on a fabricated stand and wasconnected to the smaller pulley (diameter 2.
5″) using its shaft. Smaller pulleywas then connected to the larger one (diameter 20″) using B section V belt.Larger pulley was connected to the input shaft of reduction gear box. Outputshaft of the reduction gear box was connected to the cap which would in turnrotate at 3 rpm.
Reduction gear box was fixed on a stand using a mix offabrication and use of nut and bolt. Figures 2.1 and 2.
2 show photographic viewof the developed device. C.E 2.3.5Once the product was assembled, I carried out trialson 10 caps. The results that I got were as per company’s expectations. Adetailed report of design, manufacturing and cost analysis was submitted to theplant manager.
The final product is now a permanent fixture in company’sassemble line. Figures 2.1 Figure 2.22.4 SummaryC.E 2.4.
1My work was appreciated not only by plantmanager but also the owner of company. This was my first practical experiencein a manufacturing company. I learned to do root cause analysis of any failure.I also got immense knowledge about motors and reduction gear boxes. On doingthe cost analysis of our product, we found that our product was costing INR9,000.
00 which is almost three times cheaper than the readymade motor availablein market. One more reason for me to be happy was that the entire project wascompleted within the stipulated time period.