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Linear motion: Individual components vs integrated system?

Linear motion: Individual components vs integrated system?

Integrated system: 'One phone number to call'

Dan Altermatt, Engineer, Viracon, Owatonna, MN

 

Viracon produces high-performance architectural glass at glass-fabricating facilities worldwide. Our state-of-the-art cutting, tempering, laminating, insulating, silkscreen, and coating production lines use a variety of linear actuators.

The toughest problem with actuators is controlling them. Most applications need a two-position actuator, for which pneumatics and hydraulics are ideal solutions. They are powerful, easily controlled, and inexpensive. For this application, I needed an actuator that could be told exactly where to go, how fast to get there, and how fast to stop.

The main purpose of this linear actuator is repeatedly moving a deleting head in a straight line at a fast speed. The deleting head basically is a grinding wheel driven by a dc motor that removes coating from the flat glass. The machine accommodates straight edges so the deleting head always has to move in a straight line.

The Tol-O-Matic system consists of a B3B15 series belt-driven actuator, a 3:1 reduction gear, an MRV brushless servomotor, an AXIOM DV20 drive, and a MSC microstepping controller. The stroke length of the actuator is 124 inches. It uses two Reed switches and one Hall-effect sinking switch. One, 20-minute call to Tol-O-Matic, and we had a solution. The information I gave to them included:

total move distance:120 inches

maximum load: 70 lbs

total move time: 5 seconds

dwell time: 3 minutes

maximum external thrust force: 5 lbs

The main driver for the project was the need for greater efficiency on the production line. We achieved a throughput increase in just four weeks, which included planning, designing, and building the finished product.

The edge deleter was a major part of the project. After I came up with a rough concept for it, I had to decide on the components. Because time was short and I had little experience with this type of system, I chose to have others work for me.

By having a fully integrated system designed by others, I gained hardware compatibility, field support, ease of installation, and a warranty. What I received was a system that worked right out of the box and came with everything I needed, including one telephone number to call if it didn't work.

The fact that we had one purchase order to one vendor for one system made my job easier. In the past, I've had to piece together purchases from multiple vendors. By buying separate components, I have found that you spend more time and money making sure all the pieces fit together when they arrive. Then, you hope you have all the parts you need.

My job is to make the production line work efficiently and continue improving the final product. I need to spend my time on the macroscopic project, not the microscopic details. We depend on our suppliers for providing more engineering services, system integration, and customer support. Our suppliers have expertise in what they do-it would be a waste of time to not use it. These days, time is short, stress is high, and low cost is not necessarily the most important factor.


Application Notes

OEM: Viracon, Owatonna, MN

Equipment purchased: Tol-O-Matic linear belt-driven actuator, including a 3:1 gear reducer, brushless servomotor, drive, and microstepping controller

Application: Edge deleter for flat glass

Function of actuator: Linear movement of edge deleting head

Load: 70 lbs

Distance moved: 120 inches

Accuracy: 0.0004 inch

Speed: 30 inches/sec.

Installation date: November 10, 1999

Development timetable: 3 months

Major benefits of buying integrated solution: Save valuable research, design, troubleshooting, and maintenance time. Enable field support, warranty, and ease of purchase.

 

Individual components: 'We designed a system that meets our needs exactly'

Michael McCormick, Mechanical Engineering Manager, Baldwin Enkel Corp., Rockford, IL

 

Baldwin Enkel designs and manufactures machinery for the printing and converting industries that unwinds, positions, tensions, and splices paper and other materials supplied in roll format. Typical applications include commercial printing, newspaper production, packaging and converting, business forms and envelope manufacturing.

The machine described here is a turret-style flying splicer. The term "flying" splicer indicates that the splicing function is done while the web material is in motion at speeds up to 3,000 ft/min.

A turret-style flying splicer has two pairs of roll support arms, 180 degrees apart from one another and rotating 360 degrees around a central pivot point. While one roll of paper is unwinding and feeding a precisely tensioned web through the splicer and into the downstream printing process, the opposing set of arms is positioned in a loading zone where a new roll of paper is loaded and prepared for the automatic splicing sequence.

For successful splicing, the edge of the new roll must be in alignment with the expiring web. If not, the edge of the web will be offset or overhang the new roll edge when the sheets are bonded together. One feature of this splicer is an automatic edge alignment system. As the splicehead pivots down into position during a splice cycle, a laser-eye sensor assembly (24 ounces) mounted to the a linear actuator carrier within the splicehead assembly moves towards the expiring web edge at a rate of 2 inches/second. Once the laser-eye detects the edge of the expiring web, the actuator stops and holds position within 0.30 inch, creating a reference target for the new roll edge alignment system.

The engineering development timeframe for this splicer was approximately 6 months from conception to initial delivery. Due to the short development time, complexity, and multiple subassemblies involved to engineer the entire splicing system, the use of purchased components was a must. The use of standard individual purchased components allows the end user to procure replacements direct from a local distributor..

It has been our experience that purchasing "standard" electronic drive/control packages often leads to one of two problems. On one hand, the "standard" drive/control package offered with a prepackaged system may include a wide array of control features and parameters that are not required for a particular application, therefore making it cost prohibitive. On the other hand, a "standard" control package may not have the desired control features or response characteristics for a particular application. This situation leads to either modification of the "standard" controller circuitry by the manufacturer to meet our application demands (at an increased price) or modification of the "standard" control package internally by our controls group to achieve the desired result.

By engineering our own drive and process control assemblies, we've gained the ability to design for a desired response to a specific application requirement. Troubleshooting, set-up, and response modifications are more easily managed. Although engineering time is spent in testing and development, in most circumstances, the custom-designed control package is less expensive to manufacture than purchasing a "standard" off the shelf controller. The trade-off is that implementation time may increase and the ability for the end user to procure a replacement through a distribution network is lost.

Because the machinery we manufacture combines many different power transmission, positioning, and control features to produce a splicing system, most "standard" prepackaged controllers are either cost prohibitive or do not meet our specific response requirements. From a mechanical aspect, we attempt to integrate as many purchased component systems as possible, but must base that decision on the available design envelope, operational constraints, and value engineering analysis.


Application Notes

OEM: Baldwin Enkel Corp., Rockford, IL

Equipment purchased: Tol-O-Matic Axidyne 100 Series cylinder screw actuator with motor, mount, and assembly kit (Baldwin designed its own drive and controller)

Application: Turret style flying splicer

Function of actuator: Alignment of printing press' web edge

Load: 1.5 lbs

Distance moved: 2 to 60 inches

Accuracy: 0.030 inch

Speed: 2 inches/ sec.

Installation date: June 1997

Development timetable: 6 months

Major benefits of buying components: Ability to design for a desired response.
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