final report ubidia santos

8/7/2019 FINAL REPORT UBIDIA SANTOS

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Industrial Robotics: ISE 5314

Mid-Term Report

Rotex Punch

Carlos SantosJaime Ubidia


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Table of Contents

1. Introduction

2. Objective of study

3. Understanding Rotex Punch Press

4. Rotex Punch Press Previous Mistakes

5. Rotex Punch Automation

6. Determination of Angles

7. Linkage lengths and simulation

8. Linkage Design

9. Waste Disposal Chute

10.Bill of Materials

11.Punches

12.Function Diagram

13.Process Mapping

14.Conclusions and Final remarks

15.Reference


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Introduction

The course Industrial Robotics ISE 5314 sets as the objective to design and build a sheet

metal flexible manufacturing system (FMS) at the Industrial Automation Lab located in

Durham Building. The Rotext turret punch press is a vital part of this system and as

such needs to be ready to operate and ideally should be automated.

As the team in charge of the modifications to the Rotex turret punch press, we set as our

objectives to find an optimal method for the punch to function, eliminate accumulating

scrap material from punching and ensure the safety of those operating the machine.

The Rotex turret punch press should operate in a constant, fast and reliable way so that

the overall cycle time for the FMS system can be minimized. More specifically the

mechanism should cause the machine to lower the die and retract it without exceeding

the restrictions related to the punching distance and retracting distance.

No bits of metal should accumulate on the press or be left on the metal sheet.


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Objective of Study:

The purpose of the study was to try and set-up a working Rotex Punch and the project

mainly had the following tasks:

1. Automate the turret press by using a appropriate method

2. Automate the right angle punch rotation3. Remove and correct measurement and design problems from previous groups.4. Integrate the Punch with the rest of components of the FMS system.

As noted in the PDR, the functions to be performed by the machine are being addressed

in different ways. The availability of several kinds of punches, the changes being made

to the functioning mechanism and the waste disposal chute have as an objective to

produce accurate holes and reduce the overall cost to produce this result. The solutions

the design team has been working on target the two most important requirements of

product design: compliance with the 180 constraint and removing metal bits from the

hole after punching. The constraint has changed and therefore the design complies with

the new measures.

The Rotex Punch Co., Inc. was contacted and a request for the new catalog was made

since its not available online. Although the response took some time and the arrival of

the catalog even more time, it finally arrived on Friday the 19th

of March, 2010

(Appendix 1). Most of the punches and dies needed are available and already aligned in

the turret press. A round edge punch for the corners of the parts has been installed in the

turret as well as the die and has also been aligned. This punch is a cross-like punch with

the capacity to punch four Meccano corners at the same time.

Over Travel Problem

The over travel measures taken previously by other groups were not correct and due to

this, the initially proposed mechanical model had to be forgotten. The operation system

used for the punch takes the over travel constrain into consideration and therefore the

operation of the punch doesnt rely on sensors to work properly.


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Understanding the Rotex Punch

For future modifications or upgrades to the equipment, first we needed to understand

what past groups have done to automate the Rotex Punch. In this process we had to

identify all the changes made by previous groups, how does the rotex punch work with

these new changes and what difficulties we are going to encounter because of these newmodifications.

Original Rotex Punch

The punching ram

The punching ram is the piece of the machine that needs the most force to move. This

device is what transmits the punching force to the sheet that is being punched. Previous

groups have made changes to the punch such that it can be automated. Such changes are

the following: Large 3 phase motor, mounting frame for the motor, a cam mechanismand rotational input shaft with a modification of a sprocket and roller chain which was

selected by a previous team as a cost effective and efficient method of transmitting

torque from the motor to the input shaft. Other of the innovations that came in with the

new mechanism was the implementation of micro switches so that the motor would only

manage to make the rotation necessary so that the punching ram wouldnt move more

than necessary and create any damage. Unfortunately these switches where found by

our group not being in the right position which had lead to the problems encountered by

other groups.


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The turret locking pins

The lock pins are used to properly align the punch and die for the punching process. A

spring on each pin produces the force to locate the turret in the correct locked position.

For the automation of this piece on the punch previous groups mounted an air cylinder

(Pneumatic Cylinder) near the manual lever, this device has the sufficient force toquickly release the pins using the supplied shop air. The force of the springs will return

the piston and pins to the starting position once pressure is removed.

The punch and die turret

Is the mechanism that allows for punch and die combinations to be easily changed so

different sized holes can be made without a major tool change. The turret punch was

equipped with a hand wheel, gear synchronized turrets option, which allows a

synchronized movement of both the punch turret and the die turret, using only one

input. This simplified the work for previous groups because they would only need a

motor to rotate the turret. A 120VAC 1/10 Hp 1800 rpm motor was implemented. This

motor has a 14:1 gear head that is useful to provide the necessary torque and speed

without needing a large pulley ratio. The motor is equipped with a dual round belt

pulley; the final component for this turret drive system is the belt (A 23 inch urethane o-

ring belt)


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Sensors

There are three parts on the turret press that are required to move during operation, and

therefore need feedback sensors or switches:

1. The punching ram: two SPDT micro-switches without rollers were placed toprovide feedback at either end of the rams range of motion. A wiper is attached

to the back side of the input shaft to engage the switches at either range limit.

The wiper would engage the switches to give the commands to the motor to stop

at certain limit.

2. The turret locking pins: Two SPDT micro-switches with roller levers arelocated at the top of the pin locking linkage.

3. The punch and die turret: micro switches.

Rotex Punch Press Previous Mistakes

In past reports it was noted that the angle restriction for the punching mechanism was180. Taking into consideration the implementation of a new system, as a group this

measure was taken again. As Image-1 shows, the total range of the machine is over

180, but this includes a portion of movement that has no actual impact in the punching

mechanism. The actual limit the punch has is close to 210 which gives the motor, a

buffer zone or a space for the motor to stop and change direction when retracting the

punch.

The sensors used to avoid damage on the machine while punching (for compliance with

the 180 constraint) proved to be placed erroneously and served no purpose at all.

Previous groups had assumed (according to the positioning of the sensors) a movement

of the punch 180, this was not correct.. After manual tests, the punch rotation was

determined.

Rotex Punch Automation

As applied to the Notcher machine (shown in Image-4), a linkage system was a safe

option to implement taking advantage of the constant movement of the motor. The only

difference is that in the case of the Rotex punch press, the arm would be connected to

the side of the punch instead of being on top.

A model was made to simulate the motion first, without previous calculation of thelinkage sizes and this resulted in a punch that would go beyond the desired limits. After

retrieving information from several different sources and consulting with Dr. Sturges,

the system that was found appropriate for the Punch was a four bar crank-rocker linkage

system.

A four bar crank-rocker linkage system consists of four rigid links, each attached to two

others by single joints or pivots to form a closed loop. Two of the links are grounded,

meaning they dont move, one is the input link and one is the follower link. In the case

of the Punch, the input link can rotate 360 and therefore is called a crank, while the

follower link can only rotate from a set 0 to 113 and back to 0, therefore its called a

rocker.
http://en.wikipedia.org/wiki/Jointhttp://en.wikipedia.org/wiki/Pivothttp://en.wikipedia.org/wiki/Pivothttp://en.wikipedia.org/wiki/Joint


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Image -4

Determination of Angles


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Linkage Lengths and Simulation


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Courtesy of Dr. Robert Sturges


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D = 38 cm = 15 inCrank Rocker

r (in) R (in)

Coupler

Size (cm) Coupler Size (in)

1 1,19920494 37,9585643 14,94431665

2 2,39840989 37,8339849 14,89526964

3 3,59761483 37,6254359 14,81316375

4 4,79681977 37,3315102 14,69744494

5 5,99602472 36,9501702 14,54731111

6 7,19522966 36,4786748 14,36168299

7 8,3944346 35,9134732 14,139162678 9,59363955 35,2500582 13,87797567

9 10,7928445 34,4827617 13,57589045

10 11,9920494 33,6044687 13,23010579

The determined coupler size could be modified by using the simulation tool. Trying to

find a point at which the angle of rotation wouldnt be altered too much but that would

allow for a smooth movement away from the locking point (point where the rocker and

coupler were in a straight line).

Some of the different computer simulations can be found in the attached CD, including

the final simulation with the calculated linkage lengths.


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Linkage Design

Applied moment = 71272.73*25.4 = 2299111.48.4 Nmm

M.I=20431.71mm4.

Bending = bending M = 112.5N/mm2.

I of the cross section axis

With this, the material and width of the shaft can be found to be one that withstands this

bending strength.

Torque required = 71272.73*2.933*25.4=5309.7Nm

The available motor is 0.75HP.


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Waste disposal Chute

In the past metal scrap from punching has been either accumulating or simply beingscattered around in the floor, creating a dirty and dangerous environment where workers

are exposed to sharp metal scrap. For this reason a waste disposal chute was created and

partially implemented. It will direct waste to a bin located at the bottom of the punch

press.

Utilizing 2 PVC tube and a matching elbow was the safest, longest duration, cheapest

and easiest to clean option.


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Bill of Materials

VENDOR DESCRIPTION PART # QTY PRICE STATUS

GraingerPlain Spherical Female Rod End,Thread Size 3/4-16 Inch, Right HandThread, PTFE Race

6G177 1 27,45

NEW

McMaster-Carr 12L14 Carbon Steel Square Bar 2"Square, 1' Length

6547K413 1 49,94NEW

McMaster-CarrASTM A193 Grade B7 Alloy SteelThreaded Rod Plain Finish, 3/4"-16Thread, 1' Length

98957A409 1 5,95

NEW

McMaster-CarrUltra-Coated Grade 8 Steel Hex Nut3/4"-16 Thread, 1-1/8" Width, 41/64"Height

93827A267 1 8,84

NEW

McMaster-CarrGrade 8 Alloy Steel Hex Head CapScrew Zinc Yellow-Plated, 3/4"-16Thread, 3" Length

91257A877 1 3,12

NEW

GraingerPlain Spherical Female Rod End,Thread Size 3/4-16 Inch, Right HandThread, PTFE Race

6G177

1 -AVAILABLE INSHOP

Grainger 12L14 Carbon Steel Square Bar 2"Square, 1' Length

1-

AVAILABLE INSHOP

Punches

Slot letter Slot # Size Shape

K 1 EMPTY EMPTY

J 2 size not shown Circle

I 3 19 SQ SquareH 4 7/16" Circle

G 5 3/8'' Circle

F 6 5/16'' Circle

E 7 9/32'' Circle

D 8 1/4'' Circle

C 9 7/32'' Circle

B 10 3/16'' Circle

A 11 5/32'' Circle

12 BLADE

Q 13 EMPTY EMPTY

P 14 1 1/2'' Circle

O 15 1 1/4'' Circle

N 16 1.0*1.25'' Rectangle

M 17 1.25*1.0'' Rectangle

L 18 Cross Cross


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ROTEXPUNCH

COMPONENTS

Apply Torque MotorFour Bar crank-rocker linkage

system

Energy Supply

AC powerAC power

supply

DC power24 V AC\DC

converter

Process

Selecting Punch

Sensor

PneumaticCylinder

RAM Apply torque

Safety

Hazard Label

Prevent RAM

collision

Prevented by the

linkage system

ScrapWaste disposal

chute

Function Diagram


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Process Mapping

Punching Procedure

1. Release the safety lock on the rotex punch.

2. Select the desired punch and swing the punch turret into the punching position. The

corresponding die should also swing into position by the gearing mechanism. Return the

safety lock.

3. Punch work by actuating ram.

FMS involving Rotex Punch

1. Gripper will pick the sheet from the Snuffleupagus.

2. Gripper will transport either to notcher or Rotex punch.-If sheet was transported to notcher it will then be transported to rotex punch

3. Griper will place sheet in the exact position for Rotex punch to the process that is

commanded.

4. A signal will be sent by the proximity sensors for the system to know on what punch

is the turret currently located if this is not the punch needed this sensor will send the

signal to move to the punch needed.

-If is another punch that is needed the Pneumatic Cylinder is activated to release safety

lock and permit the gear synchronized turrets be moved by a motor until the proximity

sensor sends a signal to make it stop in the correct punch selection.

5. When the punch needed is placed and the sheet is ready a command is given to start

the motor so it can give torque to the crank which in turn moves the coupler and

translates into a punch motion by the rocker. This way the punch can be made.

6. When the punch is made the ram returns to its highest point where the motor is given

a command to stop. The gripper then will move the sheet for another punch until all the

punches needed are accomplished.

-If a different diameter or shape punch is needed in this process it will return to

step 4.-When finished, the gripper will remove the sheet and continue to the notcher if

the notcher has to make more cuts.


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Flowchart

NO YES

Conclusions and Final Remarks

The Rotex punch press hasnt functioned since 2006, and this has been due to several

problems related to the punching system and its automation. The method selected is

highly appropriate and will serve to prevent malfunction and excessive rotation of the

punch ram.

Several parts of the Punch still need work but this project has been a great opportunity

to venture into different fields of engineering. The steps in the process may have not

been followed strictly enough but it has been a unique learning experience.

References

- Rotex Product Information. The Rotex Punch Company, Inc. website,http://www.rotexpunch.com

- Rotex Product Instructions Manual. The Rotex Punch Company, Inc.- ISE 5314 reports from previous years.- Constant guidance and help by Dr. Robert Sturges- Beer; Johnston. Mechanics of Materials. McGraw Hill. Second Edition. 1992

Gripper: Place

sheet on Rotex

Do we have the

punch we need?No changes

made

Punch needed

will be put in

place for usage

PUNCH THE HOLES

INTO THE SHEET

Gripper will take sheet and take to finished

products or to notcher for final cuts
http://www.rotexpunch.com/http://www.rotexpunch.com/http://www.rotexpunch.com/

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