Product FAQ

PRODUCT FAQ

Servo Roll Feeds
Air Feeds 
Stock Reels
Stock Straighteners
 
 
 

 

Servo Roll Feeds 

Why does the Feeder feed more than once during a single stroke of the press, or keep feeding even when the press is stopped?
What is a SYNC-FAULT?
Why is the Feeder inaccurate?
O.K., so how do I fix roll slippage?
O.K., so how do I prove my inaccuracy is not a Feeder control problem?
What are these error codes on the Ultra servo drive?


Why does the Feeder feed more than once during a single stroke of the press, or keep feeding even when the press is stopped?


The two cams used to synchronize the Feeder to the crankshaft must alternate their on-off signals to the Feeder’s servo drive. If at any point in the revolution of the Crankshaft the two signals overlap, or are both closed, the Feeder will do multiple indexes. If the press stops in a location where both cams are closed, the Feeder (if in Auto mode) will continually feed material without regard to crank rotation.

The Feed Cam should close on the upstroke of the press ram after the longest punches are clear of the tool, and must remain closed long enough for the Feeder to complete the index (see Sync-Fault). An example would be: Feed Cam close at 270 degrees, Feed Cam open at 90 degrees. That’s a 180-degree Cam Angle. The Continue or Reset Cam must be set the same for every tool. It is a short duration signal that occurs at Bottom Dead Center, for instance, 170 degrees to 190 degrees. When set this way, the Feed Cam goes on then off, and then a bit later, the Reset Cam goes on then off. The two cams are never on at the same time.

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What is a SYNC-FAULT?

This error is produced in the Motion Control algorithm. It is caused when the controller detects that the Feeder is still completing the index (moving) when the feed cam signal goes off/low. It is NOT a servo drive error.

-Check Feed-to-Press timing to assure feed length can be completed within the given feed cam window. See P/A Speed Chart.
-Check Feed Cam Input for bouncing contacts. The Digital Inputs on the P/A Servo Drive have Signal Propagation rates as low as 0.2 milliseconds (very fast acting). Relays or micro switches on the Press, can have contact bounce, which the feeder may detect as a very small feed cam window.
-Increase the Debounce parameter under the Setup button of the Operator Terminal. Factory default is 1 millisecond. Raise this parameter setting to 5 milliseconds.
Note: This parameter acts similarly to a dwell, in that, the program stops and waits for the Debounce period to elapse before continuing to scan. A very large Debounce time (+50 ms), can actually produce Sync-Faults in high speed applications (+350 SPM), where every millisecond is needed to feed the material up within the feed cam window. In general, if the Sync-Fault is not remedied by a Debounce setting of 20 ms or less, another cause should be investigated.

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Why is the Feeder inaccurate?

Servo Roll Feeds are by nature quite accurate if tuned properly, operated correctly, and used within design specifications. Most observed “mis-feeding” would show up as a shorter than desired feed move or index. This can most often be explained by roll slippage caused by “jerk” or kinetics. When the feed rolls accelerate from a standstill to the programmed feed velocity, energy is transferred to the material by the gripping and rotating force of the rollers. If the gripping power of the rolls is not sufficient to contain the rotational force, slip results.

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O.K., so how do I fix roll slippage?

There are many solutions to alleviate “jerk” or kinetics. The first step is to be sure  that the springs (or Air Cylinders on larger models) are tightened enough to grip the material, but no so tight as to deform the material itself. At five turns (maximum) from finger tight, the adjustment nuts and springs apply nearly 2000 pounds of pressure onto the strip.

Next, check the timing of the Press Feeder signals. If the Feeder tries to feed the material before the tool is fully open, slip or buckling will result. If the rolls open for piloting before the pilot pins have control of the strip, the material can slide backward due to the weight of the loop. If the rolls stay open too long, the material can again slip backward when the pilots leave the strip. When the rolls close, the Feeder feeds the correct index, and the material’s positioning is short.

Tooling problems such as tightness in the die, material guides too tight etc., can all cause misfeeding.

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O.K., so how do I prove my inaccuracy is not a Feeder control problem?

The quickest way is to remove the material from the Tool and Feeder. Then enter a feed length into the Feeder equal to one full revolution of the Feeder’s lower roll (it’s Circumference). The accuracy of this number is based on the roll’s diameter, the motor’s encoder resolution and gearing, scale parameter, etc. The correct number can be found in the manual under “How A Servo Feed Operates”. Ultra Edge and Advantages have a roll circumference of 11.142 inches or 283 mm. Shut the Feeder off, CAREFULLY remove the belt cover to expose the timing sheaves. Put a mark on the larger timing sheave and a corresponding mark on the motor adapter plate so the marks are aligned to one another. Now, power up the Feeder (use extreme care operating the Feeder with the belt exposed). Check that the feed length is 11.142, put the Feeder into auto and stroke the press 500 to 1000 times. If the “scale” of the Feeder is correct, the marks should stay lined up regardless of how many indexes are done.

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What are these error codes on the Ultra servo drive?

E-0-4: Motor Over Temperature: The Motor's Thermistor circuit has opened, indicating an overheat condition.

A Thermistor is a solid-state device that has a certain resistance to voltage flow at some designed nominal temperature. At the Motor's designed high temperature limit of 140 degrees Celsius (284 degrees Fahrenheit), the Thermistor’s decreased resistance triggers a fault circuit. When the motor cools below a designed limit, the resistance also rises within limits, allowing the fault circuit to reset.

A closed voltage loop exists; sourced at the Servo Amplifier (Drive), extending out through the encoder cable, into the windings of the motor, through the Thermistor, then back, through the encoder cable to the Drive. A completed circuit of this voltage indicates to the Servo Drive, that the motor is within operating temperature. However, a break in this loop, other than the Thermistor opening, causes the drive to assume the motor is in an Over Temperature state, when in fact the motor is cool.

-Broken encoder cable wiring, loose connections, or a disconnected motor can cause this error.
-Of course, a VERY hot motor can indicate the same error. If the Motor is too hot to touch, a very serious problem exists with excessive current or loading on the system. As a rule, P/A Servo Feed Motors do NOT run at very high temperature.
-If the drive is an older DDM-30 drive, the J4 Motor Encoder connector on the front of the drive is VERY delicate. If this connector is moved side to side, pins can be broken on the connector's header. This CANNOT be repaired. The drive must be replaced. Be VERY careful handling this J4 connector.



E-0-5: IPM Fault: This is a serious problem with the Servo Amplifier's IPM module. The Intelligent Power Module processes all current, and phasing requirements to the Stator (stationary windings) of the Motor. A maximum of thirty peak amperes is allow through any phase of the motor for a short duration. Continuous current of ten amperes is allowed. When either the Continuous, or the Peak Currents, are exceeded in both amplitude and time, an IPM Fault is generated.

-Axis, Feeder, or Material locked. Extreme mechanical binding, tooling problem, tight loop, pulled slug, etc. Basically, anything that can cause the motor to lock-up, or be difficult to turn.
-Incorrect Motor Phasing. The four Motor wires MUST be connected properly on the Amplifier and Military connector. (A)BROWN to U or R, (B)BLACK to V or S, (C)BLUE to W or T, the (D)GREEN with YELLOW to GROUND or GND,
-Short Circuit in the Motor wiring or windings. The motor's Phase to Phase resistance should be equal and at a value of about 100 ohms or less. Each phase to the green/ground should show infinite resistance. The cable should be checked for continuity and shorts.



E-1-0: Bus Over Voltage Error: The D.C Bus Voltage has exceeded the maximum threshold of 392 VDC. The nominal Voltage measured across DC Bus+ and DC Bus- is 375 VDC. This rectified voltage is based on a maximum incoming Line Voltage of 240 VAC.

-Check the Line voltage to be sure it is between 88 and 240 VAC.
-Make sure the feed supply is not shared with other regenerative drive equipment.
-Deceleration of large strips after a long feedlength (six+ feet), can cause excessive regenerated voltage that pushes the Bus Voltage above it's maximum threshold. Lower the deceleration parameter.
-Line voltage spikes can send the Bus Voltage over it's maximum threshold. Install a Three KVA, Single Phase, transformer as a Line buffer. Wire the Primary Coil to match the Line Voltage, and the Secondary Coil, to output 210-220VAC Single Phase to the feed control.



E-1-1: Illegal Hall State Error: Usually caused by poor encoder cable connections at the motor's military type encoder connector.

-Power down, remove both motor connectors, spray with contact cleaner, blow out excess until dry, reconnect, repower.
-Check encoder cable for damage. Replace if damaged.
-Motor's Hall effect encoder damaged. Replace motor.



E-1-8: Overspeed Fault Error: May be caused by incorrect speed entry in the tool. Verify that the SPEED setting for the tool is within the capabilities of the system. Refer to "Feeder Scale Value" help page for maximum velocity settings, at nominal line voltage, of different P/A Systems. May also be caused by defective encoder cable, or bad connections to encoder. See E-24 below.



E-1-9: Excess Position Error: Usually caused by defective encoder cable, or bad connections to encoder. Power down, remove connectors, spray with contact cleaner, blow out excess until dry, reconnect, repower.

-Check encoder cable for damage. Replace if damaged.
-Motor's encoder damaged. Replace motor.



E-2-2: Motor Thermal Protection Fault: This is a digital filter that protects the Servo Motor. Tripping of the filter limit is usually caused by increased mechanical resistance in the Feeder, the application, dips in Line voltage, etc. Look for pulled slugs, cambered material, tool binding, mechanical resistance of the feed rolls, proper line voltage, poor connections, etc. (See IPM & Motor Thermo Error Document).



E-2-3: IPM Thermal Protection Fault: This is a digital filter that protects the Intelligent Power Module. Tripping of the filter limit is usually caused by increased mechanical resistance in the Feeder, or the application. Look for pulled slugs, cambered material, tool binding, mechanical resistance of the feed rolls, etc. (See IPM & Motor Thermo Error Document).



E-2-4: Excess Velocity Error: Usually caused by defective encoder cable, or bad connections to encoder.

-Power down, remove connectors, spray with contact cleaner, blow out excess until dry, reconnect, repower.
-Check encoder cable for damage. Replace if damaged.
-Motor's encoder damaged. Replace motor.



Sync-Fault: This error is produced in the Motion Control algorithm. It is caused when the controller detects that the Feeder is still completing the index (moving), when the feed cam signal goes off/low. It is NOT a servo drive error.

-Check feed to press timing to assure feed length can be completed within the given feed cam window. See P/A Speed Chart.
-Check Feed Cam Input for bouncing contacts. The Digital Inputs on the P/A Servo Drive have Signal Propagation rates as low as 0.2 milliseconds (very fast acting). Relays or micro switches on the Press, can have contact bounce, which the Feeder may detect as a very small feed cam window.
-Increase the Debounce parameter under the Setup button of the Operator Terminal. Factory default is 1 millisecond, raise this parameter setting to 5 milliseconds.
Note: The Debounce parameter acts similar to a dwell, in that, the program stops, and waits for the Debounce period to elapse before continuing to scan. A very large Debounce time (+50 ms), can actually produce Sync-Faults in high speed applications (+350 SPM) where every millisecond is needed to feed the material up within the feed cam window. In general, if the Sync-Fault is not remedied by a Debounce setting of 20 ms or less, another cause should be investigated.


 

 

 

Air Feeds

Should air be leaking from the main exhaust port on the Air Feed?
Why does the strip slip backward?
What type, and how much oil should I put into my Air Feed?
Can I use WD-40 to clean the Air Feed?
Can I reverse the feed direction of my Air Feed?
How many cycles/strokes can I expect from my Air Feed before I will need to install a repair kit?
The Air Feed’s clamps have different coil springs; one set is lighter gauge wire than the other set. Where do they go?
How much clearance should be provided between the Air Feed’s clamps and the material?


Should air be leaking from the main exhaust port on the Air Feed?

Air is only exhausted to atmosphere from the main exhaust on the retract stroke (feeding portion) of the cycle. This is the air trapped behind the main piston rod and needs to be evacuated to allow the feed head to move toward the main body during feeding. This trapped air is throttled through the Speed Adjustment Screw to allow control of the feed head feeding speed.

If air is leaking at any other time, it indicates a failed o-ring in the circuitry. The most likely sources are the feed head piston o-rings.

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Why does the strip slip backward?

The Feed Head Clamp and Stock Clamp must precisely sequence in order to prevent pullback. Pullback is caused by the constant pressure of the free loop of material held by the feeder. Gravity pulls the loop downward causing pull on the feeder’s clamps opposite to the feed direction. One of the Air Feed’s clamps must hold the material at all times (except during pilot release). If both clamps are free of the strip, even for a few milliseconds, the material will move backward away from the tool. There are two primary causes of pullback. The Cartridge Valve (11), and the Clamp Springs (64 & 23). If the Cartridge Valve malfunctions due to debris or wear, the clamp sequencing and feed head motion will be affected. If the wrong springs are placed under the clamps, the clamps will not sequence properly. The springs with the heavier gauge wire should be placed under the Stock Clamp on the Main Body of the Air Feed.

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What type, and how much oil should I put into my Air Feed?

P/A recommends a light (30-32 weight), hydraulic oil such as Shell Tellus Plus 32 or equivalent. As to how much oil to entrain into the supply air stream, for most applications, set the Filter-Regulator-Lubricator to between 1 and 2 drops per minute. This amount can vary slightly depending on the size of the feeder, the stroke length, and cycles per minute.

Remember, this is an AIR Feed, not a HYDRAULIC feed. Too much oil can cause many feed related problems.

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Can I use WD-40 to clean the Air Feed?

NO! WD-40’s chemistry contains materials that are extremely harmful to Buna-N O-Rings. In addition, its “rust preventive” ingredient contains paraffin (wax), which can cause gumming and binding on surfaces, as well as collecting airborne impurities.

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Can I reverse the feed direction of my Air Feed?

No. The P/A Air Feeds are not able to reverse the feed direction. The entire Feed must be remounted to feed in the opposite direction.

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How many cycles/strokes can I expect from my Air Feed before I will need to install a repair kit?

In general, if the Air Feed is supplied with Clean, Dry, Properly Lubricated Air at the recommended pressure; between 3 million, and 4 million cycles can be expected.

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The Air Feed’s clamps have different coil springs; one set is lighter gauge wire than the other set. Where do they go?

The heavier gauge wire springs are placed under the Stock Clamp on the feed body. The lighter gauge springs are placed under the feed head clamp (movable).

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How much clearance should be provided between the Air Feed’s clamps and the material?

With the air turned off to the Air Feed, the clamps should be in their full up position. The clearance between the clamp and the top of the material should be approximately .015 of an inch, and equal across the entire width of the material. This distance will provide the quickest clamp action, and should allow the feed clamp to move back and forth without marking the material.

 

 

 


Stock Reels

How do I make the Reel turn faster?
How do I know the maximum coil weight I can expect my Stock Reel to support?


How do I make the Reel turn faster?

All P/A Stock Reels have variable speed motor controls. These controls are in turn, controlled by the Loop Control Device. This Loop Control may be a simple On/Off type LC-2, or a sophisticated Ultrasonic No-Touch type. In addition, the motor controls themselves can vary depending on the product. From simple D.C. Type controls, D.C. Regenerative Controls, or Variable Frequency A.C. Drives.

Maximum Speed, is RPM at the coil’s smallest diameter where the Reel must rotate at it’s fastest speed to payoff or take-up the material. Response is the time it takes for the drive to "respond" to the Loop Control's "command" to go faster. If the Loop Control is putting out it's maximum signal to the drive, and the drive is unable to keep up, this could indicate a Maximum RPM problem. Meaning, the existing design components in the reel only allow it turn at that maximum speed. In this case, going "faster" might require a different gear ratio or pulley configuration in the drive train.

Most variable speed drives have provisions to increase Maximum Motor Speed such as Max Speed Potentiometers, or a parameter that increases the Maximum Frequency. Check the drive manual that was provided with the Reel. In general, if your Reel does not "keep up" with the production line it is currently in, and all adjustments to increase maximum RPM have been made, a quick call to the P/A Service Department might be in order. Remember to have the Model Number and Serial Number handy for the Service Tech.

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How do I know the maximum coil weight I can expect my Stock Reel to support?

Each P/A Model Number contains the Maximum Capacity of the Stock Reel. For instance, P/A Model: SRA-2624-D = translates to: Stock Reel Adjustable- “2600” Pound capacity with a maximum “24” inch material width (2624), - Dancer Arm speed/loop control.

 

 

 


Stock Straighteners

How far should the Straightener be from the Feeder?
How do I adjust the Straightener Rolls to get my material flat?


How far should the Straightener be from the Feeder?

The distance between the Straightener and Feeder is based on the thickness of the thickest material that will be run in the Press line. After the material is straightened, it is important not to reintroduce “set” into the material by bending too tightly going into and out of the free loop provided to the feeder. On the other hand, having the machines too far apart actually reduces the amount of slack material in the loop available for the Feeder.

Four radii of 90 degrees each can represent the flow of the material down out of the Straightener over and up to the Feeder. This totals 360 degrees. 180 degrees of bending in each direction, down and up. The distance of the radii determines how much bending of the strip takes place. By placing the machines too close together for a given material thickness, the material might be re-bent, and not be flat by the time it gets to the tool.

An easy formula to use is 1440 (360 X 4) X Material thickness = the distance in inches of separation between the Straightener exit and the Feeder entrance. An example would be: The thickest material that will be used in the line is .093”. Therefore, 1440 x .093 = 134 inches. 134 / 12 = 11 feet. The Straightener should be secured to the floor 11 ft. from the Feeder.

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How do I adjust the Straightener Rolls to get my material flat?

There is no simple answer to that question. Every material has different characteristics with regard to chemistry, tensile strength, and modulus. There is no exact science in getting desired flatness with a certain material. But as a general rule, the harder and/or thinner the material, the more straightening rolls are needed. It's preferable to do as little bending or penetration of the rolls as possible, to get the desired result.

The theory is to back bend the material with the first straightening roll, putting enough work into it to overcome the coil set at the beginning of the coil and at the end of the coil where the coil set is the most severe. Each roll following the first applies slightly less bending moment until the material exits. The last two rolls can be adjusted to get a slight up-bend, down-bend, or dead flat.

A good starting point with the first roll is to adjust it down until it contacts the material, then adjust the roll down to bend the material equal to it’s thickness. Try to use test strips that are easy to handle, say three feet long. Each test strip can be run through the straightener up to three times to test the adjustment results.

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