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The Case for Compact Feed Lines

By: Robert Allred

Robert Allred is sales and marketing manager, The Minster Machine Co., Automation Div., Minster, OH: tel. 419/628-2331, www.minster.com.

Friday, May 01, 2009
 
 
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Every few years a new catch phrase floats
Spec your feed line with optionl straightener-head opening action
Spec your feed line with optional straightener-head opening action to allow for easy access to the rolls, for cleaning. This proves particularly useful to stampers that switch from forming hot-rolled scaly material to cold-rolled steel or aluminum on the same machine.
around the industry until it becomes a bit generic, such as “servo feed” in the early 1980s and “servo press” more recently. Not long ago, no one had heard much of the “compact feed,” introduced in the early 1990s and many years later becoming another of those catch phrases.

Years ago, when a metalformer required additional space to make room for a traditional long-loop line, it would construct an addition to its building. Things have changed a bit, and now companies strive to make as much use of their existing space as possible. This increase in the value of space has als been a consideration in Europe, and explains why much of the technology for compact feed lines has come out of Europe, and now has spread to the United States.

However, a compact line does not als represent the best solution. What factors should metalformers consider?

1) Strokes per minute. If your job requires high speeds or very long feed lengths, a long-loop line offers the best solution. Applications where feed length exceeds 30 in. and exceeds 30 to 35 strokes/min. tax a compact feed line. For example, a motor-lamination stamper never would be able to attain the speeds needed—500 strokes/min. with a 4-in. feed length—with a compact system.

2) Surface-critical material. Since a compact line stops at each stroke, feed and straightening rolls also stop. During this stop time, the machinery might leave a witness or shadow mark across the width of the material. This might be acceptable when stamping nonsurface-critical parts, but when running pre-polished material that becomes the finished product, these marks likely will be visible, and unacceptable. In these cases, applying a long-loop line—where the material continues to travel through the straightener without stopping until the line stops—offers the optimum solution. Also important is the addition of a variable-speed drive on the straightener, to eliminate unnecessary starts and stops. The loop control provides a more fluid speed output to the straightener, eliminating the start/stop problem. Also add a good ultrasonic or laser loop sensor.

Cradle or Reel? Single or Dual?

Once the above-mentioned criteria are understood and a metalformer remains a candidate for a compact line, the next consideration is coil handling.

• Cradle or a reel?

• Dual reel or a single with a coil car?

• Single or dual cradle, or a cradle with a staging unit behind the primary cradle?

Among the application specifics to consider is the maximum thickness and maximum width the metalformer intends to run. Depending on the maximum sheet thickness, a cradle may offer a better solution than a vertical reel.

The most common configuration of a compact line, the reel feeder-straightener, gets the call when material is not excessively thick and marking of the coil OD is surface critical. A cradle is not a good choice for stampers running very thin material, say 0.016 in. thick, or narrow-width coils. Processing a lot of partial-run coils also sets the stage for using a reel, which makes rewinding the partial coil a simple task provided it’s equipped with proper coil-holddown arms. Holddown arms also keep the coil tight while rewinding, a difficult if not impossible task to accomplish with a cradle. And, stampers that run dies off center also opt for a reel, since most cradles are self-centering with little provision for off-center movement.

Having selected a reel setup, now the stamper must choose between a single- or dual-reel installation. A dual-reel system requires room on the plant floor to allow the decoilers to swing out. A single-reel setup with a coil car requires less floor space, and our studies indicate that stampers will experience little difference in coil-change time between a dual-reel setup and a single reel with coil car.

Power Options

A peeler/threading table promotes hands-free and safe coil threading into the straightener-feeder head.
A peeler/threading table promotes
hands-free and safe coil threading into the straightener-feeder head. An extendable peeler tongue reaches the leading edge of the coil to help peel it a
from the mandrel, and the threading table pivots to assist in safely moving
the coil under the straightening rolls.

To provide sufficient power to decoil and rewind on a reel, the unit typically must include a hydraulic or a variable-frequency drive. Also, to provide enough power to expand the mandrel on the coil ID, metalformers can opt for a hydraulic-expansion feature. Mechanically, expansion is best accomplished with the use of wedges; however, this limits the expansion range. For lighter-weight coils, a linkage mechanism offers greater range but is not as robust.

Another consideration is the degree of automation required. For shops that change jobs frequently and want to eliminate the potential for operator error, an automated system may provide the best solution. Here, an operator enters a job number into the system controller, which has previously been saved, to automatically recall the parameters for a job.

When specifying an automated line, detail these parameters:

1) Feed length/progression

2) Straightener settings/straightener-roll penetration

3) Speed (strokes/min.)

4) Feed-line height

5) Traversing reel location, based on the width of the material

6) Coil-cone keeper location, based on the width of the material

7) Motorized guide rollers—entry and exit.

Meanwhile, stampers that change coils less frequently or do not require a great degree of sophistication can make do with a standard line. Specify these parameters:

1) Powered-straightener settings/ straightener-roll penetration

2) Powered feed-line height adjustment

3) Powered peeler and threading table

4) Hydraulic coil-reel expansion and rotation (for power).

With this style of feed line the metalformer obtains some level of automation, along with manual coil centering and setting of coil-keeper location. Consider the addition of a coil car to assist with locating the coil on the mandrel, which will quicken coil changes and prevent damage to the coil during loading.

 

 
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See also: Nidec Minster Corporation

Related Enterprise Zones: Coil Handling

 


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