Cold Rolling Experiment

Cold Rolling Experiment Sec 505B Derick Onyewuenyi Onyewuenyi 2/26/12 Report submitted to: Clayton Moore

2

Summary The objective of this lab was to gain a deeper understanding of the practice of cold rolling and how to arrive at properties. This cold rolling experiment started off by measuring the dimensions of 4 brass specimens that had different dimensions and recording their thickness and width in millimeters. Next we cold rolle d each specimen and measured their hardness three times each. Lastly we calculated each specimens area and percent cold work, this was the conclusion of the data we recovered from our experiment. Initially after cold rolling the first specimen I felt that the hardness values for each specimen would not vary that much and I was correct to an extent. Our average hardness values did not deviate by that much and there standard deviation for all three trials was pretty low. Overall this was very quick and valuable experiment were we learned a lot about cold rolling.

3

Table of Contents Summary

Page 2

List of Equations

Page 4

List of Tables

Page 5

List of Figures

Page 6

Objectives

Page 7

Introduction

Page 7

Theory

Pages 8

Test Description

Page 9-10

Results

Pages 11

Discussion

Pages 12

Conclusion

Pages 13

References

Page 14

Appendix Data Sheet

Page 15

4

List of Equations Equation 1:

Area = Thickness * Width

Equation 2:

%Cold Work=((d0- d1)/d1)*100%

Equation 3:

5

List of Tables Table 1: Test Results

6

List of figures

Figure 1: Hardness Machine Figure 2: Wrench Figure 3: Tightening Bolts Figure 4: Red Lever Figure 5: Rollers Figure 6: Brass Specimens Figure 7: Hardness vs %CW

7

Objectives We cold rolled and tested four brass specimens consisting of different dimensions. Our aim approaching this experiment was to measure the hardness values of each specimen and analyze the hardness for each one. The second aim for the experiment to calculate and analyze the percent cold work for each specimen. Approaching the problem at first my entire group expected the cold rolling not to play that much of a part in effecting the average hardness values for each specimen. There for we felt that the hardness values for each specimen would be close to the same. We also felt that the percent cold work for ach specimen would not differ by that much as well.

Introduction Cold rolling is often used in engineering for various purposes and is essential to a lot of  the everyday things we used in our society. There are a large variety of different materials in our world that are used for a wide variety of applications. Cold rolling is a very useful tool to transform materials so that they meet the requirements for their intended uses. As I talked about in previous experiments material properties are very important when it comes to the use and application of materials. In our world today almost every man made physical item that we use on a day to day basis contains materials that were analyzed and tested so that they an perform at their users liking. Cold rolling is a key tool to adjust the material properties in car engines, airplanes, cell phones, houses, and almost everything common to our everyd ay use. My group and I did this experiment to dive into a deeper look at how cold rolling actually works and the hidden science behind this practice. Our group wanted to attain this knowledge to increase our engineering capabilities. Cold rolling opens up a door to allow engineers to use almost any material to their liking and takes care of a lot of the difficulties behind finding the right material for a given project. Overall this was a valuable experience to each and every one of my group members, we now have the knowledge to use a cold rolling machine and cold roll and adjust materials to our own unique specifications.

8

Theory

The earliest recorded use of cold rolling dates all the way back to 1480 and the machine in which this was done was designed by the great Leonardo da Vinci. Back in these days the practice of cold rolling was mainly used by gold smiths to flatten and transform silver and gold. Back then the practice was not as serious but it became to pick up speed when it arrived in America. The first rolling mill established in America was built in 1751 and was used to roll down steel bars. Since then cold rolling has evolved into a very sophisticated and useful practice. The process of old rolling may seem very simple but in actuality is ve ry complex. The theory of this practice contains a variety of important concepts that need to be understood before a significant grasp of the concept can be obtained. To begin several assumptions must be made to assure apprehension. First is that there is no elastic deformation and the coefficient of friction is constant at all points on the surface of the specimen. Second is that the deformation is homogenous. Now during the rolling process you have several forces acting in the vertical direction that are balanced out by the pressure created by the roll. In an ideal cold rolling practice the portion of the roll that makes contact with the surface is completely flat. The total rolling pressure (P) is calculated by multiplying the specific rolling force by the width of the specimen. The two bending rollers during the process roll in opposite directions of each other. The space between these two rollers is smaller than the width of the rectangular specimen that you are trying to roll, this in turn causes the specimen to deform. Phenomena of friction is what causes the specimen to continue through the rollers without this action the metal cold rolling would not work. Now because the thickness is decreases this causes the material to increase in length. The conclusion of this process is often the i ncrease in the tensile strength and the hardness of  the specimen, ductility is thus decreased.

9

Test Description The first thing we did was recognize and define all the tools that we used during the experiment. The first utilized tool was four specimens of brass that each had its unique rectangular dimensions. These specimens were the basis for which our group conducted and learned about the cold rolling experiment. The second and main tool used was the actual cold rolling machine. This was the machine were the cold rolling took place and each individual specimen was deformed. Another key part was the hardness measuring machine which was used in our previous experiment as well. This was the machine that measured the hardness of  each material after we cold rolled it. Another tool used in this experiment was an electronic ruler that was used to measure the dimensions of our brass specimens. The last and final tool used was a wrench which was used to tighten and loosen n uts that adjusted the space in between the two rollers. The first step in the experiment was to measure the dimensions of the four brass specimens . We did this with the electronic ruler, after we measured them we recorded the thickness and width on our data sheet. Next, we adjusted the cold roller to the speed that we wanted and used the wrench to tighten the roller to the spacing that we wanted. Once the rollers were at the correct spacing it was time to feed the specimen into the lips of the rollers. Once the specimen is secure in the lips of the roller we located the red lever and pulled it down to power on the roller to start the actual cold rolling process. After the brass specimen passed through the roller it is now deformed and now it is time to test its hardness .Now we walked the specimen over to the hardness testing machine and repeated the hardness test by attaching the indenter and placing the specimen securely on the platform. After the test was complete we recorded the hardness and repeated the hardness test three times in total for each specimen. We repeated this same process for each specimen.

Figure 5: Rollers

Figure 6: Brass Specimens

10

Figure 3: Tightening Bolts

Figure 1: Hadness Machine

Figure 4: Red Lever

Figure 2: Wrench

11

Results

Table 1: Results Spec #

Thickness(mm)

Width(mm)

C/S Area

% Cold Work

Hardness Avergae

Hardness STD

1

2.38

12.92

30.7496

1.4

39.96

0.73711

2

2.17

13.71

29.7507

2.49

43.1

0.36056

3

1.74

14.87

25.8738

12.68

50

0.52915

4

1.48

14.98

22.1704

27.55

50.6

1.8735

Hardness vs %CW 30 25 20

Hardness 15

Series1

10

Linear (Series1)

5 0 0

0.5

%CW

Figure 7: Hardness vs %CW

1

1.5

2

12

Discussion In this experiment we analyzed and tested the cold rolling process and its effects on four brass specimens of different dimensions..We did this by practice cold rolling where we measured and recorded the dimensions of four brass specimens, fed them into the cold rolling machine, and tested/recorded each specimen’s hardness. As we analyzed our findings we came to the conclusion that as the larger area for each specimen led to a higher average hardness. Our group expected this relationship to occur and thus were not as surprised by our findings. We also came to the conclusion that the as the area increased and as the hardness increased so did the percent cold work. To put into analysis terms each property on the data sheet followed a positive direct correlation.

13

Conclusion From the experiment it can be seen that we met our goals in being able to get a deeper understanding of cold rolling and being able to analyze its affects on hardness and other material properties specimens being tested. The experiment satisfied our goals because we now understand how to perform a cold rolling experiment and now understand the science behind it. All the tools in the lab worked properly and our entire group was able to interact with the tools and lab instructor and gain valuable experience that can be used in the future. This time around all of our calculations were accurate and we felt confident about our analysis thereof. I not only know how cold rolling works but I now understand the hidden science behind cold rolling and the affects it has on the materials being rolled. I feel satisfied with my new found knowledge and look forward to building on them in future engineering coursework and future engineering experiences.

14

References





Callister, William D., and David G. Rethwisch. "Chapter 6.2." Materials Science and Engineering: An Introduction. New York: Wiley, 20010

Mechanics of Materials: M. Vable. P rin ted from: http://w w w .me.m tu.edu/mavab le/MoM.

2nd.htm. 

http://www.me.mtu.edu



ABES Engineering design



www.matweb.com

15

Appendix Attached: Excel Calculations and Experiment Data File

16