When die operations cause the carrier to move, it usually will be required to flex or stretch。 Regardless of carrier flexing, their key function is to move the parts close enough to the next station so that pilots, gauges and locators can put the parts into their precise location as the die closes。

If the carrier acquires a permanent stretch, the parts may progress too far to fit on the next station, or in the case that the die has two carriers, one carrier may develop permanent stretch with no stretch in the other carrier。 This will create edge camber in the strip, causing it to veer to one side。 This results in poor part location。

A stretched carrier can be shortened to its correct length by putting a dimple in the carrier。 If a center carrier or one-sided carrier develops camber, the strip can be straightened by dimpling or scoring one side of the carrier。 Construct the dimple and scoring punches so that they are easily adjusted sideways for position and vertically for depth。

as it is delivered from the coil can cause the strip to bind in the running gauges that guide the material during the feed cycle。 This binding may cause the carriers to buckle, which results in short feeds。 It often helps to relieve the guide edge of the gauges in between stations and have tighter gauge control at the work station。

Another option is to eliminate camber by trimming both sides of the material in the beginning of the die。 By adding stops at the end of these trim notches they can be used as pitch control notches to prevent progression overfeed。

Optimum Carrier Profile

The optimum carrier profile is affected by some of the following conditions:

• Space available between parts: Try to keep the carriers within the stock width and pitch required for the blank。 If this is not possible then the designer must add to the width and/or the progression of the material to provide adequate carrier room。

• Attachment points to the part: If two carriers are used, try to keep the profile and length of the carriers somewhat the same so that any effect of carrier flexing is close to being balanced。 

• Clearance for punch and die blocks: Punch blocks that extend below the stock or die blocks that extend above the stock when the die closes will require clearance in relation to the parts and the carriers。 If a loop of the carrier interferes with blocks it may be possible to form the loop vertical to provide clearance。 

• Thickness of the material: Large parts with thin material may require stiffener beads to add strength to the carrier for stock feeding。 Another stiffening and strip guiding method is to lance and flange the edge of the stock, which also can be used as a progression notch。

• The total of the strip: Heavy parts in long dies require more force to push the strip through the die。 However, the weight is usually thick material, and thick material is stiffer than thin material。 As a rule of thumb, flexible carriers for materials of 0。020 in。 to 0。060 in。 are about 3/16 in。 to 5/16 in。 wide。 For stock thicknesses above and below this thickness range, carrier width is a "best judgment call。" 论文网

Depending on all the die factors involved, under normal conditions the carriers should be a consistent width for their full length, but especially in the area of flexing。 Since nearly every stock feeder pushes material through the die rather than pull the material, the carrier must be strong enough to push the parts all the way through the die。

A detection switch actuated by a complete feed of the strip at the exit of the die can detect buckling。 If action of the die during closure or opening of the press requires the carriers to flex, design the carrier with loops that are long enough to flex without breaking, but still strong enough to feed all the parts to their full progression。 If two flex carriers are not strong enough to feed the strip, consider three carriers。