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The Robotic Work Cell - A Case Study

Project Requirements

To give you some background, on this robotic work cell please see - "Part Marking-a Case Study"

The same customer's business, has increased to the point, that an operator was utilized, for 8 hours per day, loading and unloading, the simple fixture. The part mix, lead us to believe, that a fully automatic, robot system, could be justified, along with keeping the existing system, for the shorter runs.

robotic Cell

Existing system from Telesis.

An examination of the parts being produced, revealed that there are 4, high production parts, with average batch size, of greater than 50. The cost of small, Scara type robots have fallen dramatically, recently, making many more applications, financially viable. Initial discussions with the customer, established a budget of $60,000,for this project. A system, that could be loaded with parts, and run, un-attended, for, a reasonable amount of time, was the prime requirement.

THE SOLUTION

It was decided to custom design, a robotic work cell, with myself responsible for machine design and project management.

The first task, was to select the hardware, best suited for the application.

The choice of robot, was quite wide, but eventually, Epson was decided upon. This robot has been used before and local representation was available, making after-sales-service, readily available.

The dot-matrix marker chosen was Technifor. Their unit interfaced well with the robot and the overall robotic, concept.

To visit the Epson website-click photo.

The Epson robot selected, was a model E2S654S, with Vision.

To visit the Technifor web site,click photo.

The Technifor unit selected was a model-CN212Cp

The Epson vision system was chosen, to simplify the location of the parts. In order to maximize the run time, of the cell, it is necessary to place as many parts as possible, inside the robot work envelope. It was possible to locate 7 special trays, in position. Each tray can accommodate up to 52 parts, randomly placed. The vision system will guide the robot, to the final part position. Note that the trays are hard black anodized and the parts are natural aluminum, in color, thus giving good contrast, for the vision camera.

MACHINE SEQUENCE AND ESTIMATED CYCLE TIME.

A batch of parts, will be placed in the trays and the trays placed in the cell (trays are pin located). Trays are sensed to be in position by proximity switches, tapped into the table plate. Please note that all parts must be the same, in all trays.
The cell doors are closed, and the program selected, to suit the part, via the operator panel (MMI).
The robot moves to the first tray, and the vision guides the gripper to it's final position, over a part. Estimated time-4 secs.
The gripper moves down, inside the part and expands to grip. (note that the gripper fingers have 4 different diameters, at 4 stepped heights, to suit the 4 selected parts, thus the robot moves to the correct height, to suit the part selected.) Estimated time-4 secs.
The robot moves the part, to the Technifor part marker. Estimated time-4 secs.
The part is marked, around it's periphery, as it is rotated. Estimated time-6 secs.
The robot moves the part to the unload chute, where the gripper is released and the part slides out of the cell, into a shipping box. Note that the part is sensed by a through-beam photo-cell and the part count is displayed and reordered. Estimated time-6 secs.

ESTIMATED TOTAL CYCLE TIME-24 SECS PER PART.

SAFETY AND GUARDING.

This subject is discussed, in more detail at "Robot Safety", another page at this website.

Square Mechanical Tubing, was used, on this project, 1/1/2"square. There are a total of 6 doors, on 3 sides of the cell. Each door has a "Schmersal" switch, mounted. These switches are specifically designed for guarding and are recommended, to be seriously considered. Click here to visit their site

ENGINEERING NOTES

Autocad(2D)was used, for the initial design layout, of this robotic cell, then Solidworks(3D)was utilized for the final design and detailing. To view PDF files of some of the general arrangement drawings, click on these links-

AUTOCAD (2D) GENERAL ARRANGEMENT.
SOLIDWORKS(3D) GENERAL ARRANGEMENT.
Please note that the guarding is omitted from this drawing, for the sake of clarity.
SOLIDWORKS(3D) TRAY ASSEMBLY

PROJECT MANAGEMENT

As soon as the engineering was complete, 3 quotations were obtained, from local machine shops and electrical panel builders. The chosen suppliers (based upon delivery, prior similar experience and price) were advised. Requisitions were then issued to the customer, who then generated purchase orders. Requisitions were also issued, for the robot, the part marker and all other purchased items required. It was then possible, to detail a schedule, showing final delivery of the completed robotic cell.

The total engineering hours, were approximately 150,with a further 50 hours of project management time. The total elapsed time, from initial customer talks to final delivery, was 4 1/2 months.

For information on robotic welding, click here.

If you require more information, on this robotic cell, or would like to discuss your project, in more detail, please contact us, by using the form below. Please be assured, that your information will be kept confidential.


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