FORMING AND FABRICATING AUTOMATION
H ere we take a deep dive into ball disadvantages of each. Moving Dies
A Proper QDC Setup: 1. Makes all of the relevant dies look the same to the equipment that’s going to move them 2. Maximizes offline work 3. Has the next die ready to go into the press. Expanding on item 1, if planning to latch onto one die in two places 20 in. from the centerline, then latch onto all of the dies in two places 20 in. from the centerline. Similarly, if, when landed, the attachment points of one die end up 6 in. inboard of the bolster’s edge, then ensure that all of the dies have attach- ment points located 6 in. inboard of the bolster’s edge. A typical strategy: Pick the largest die and make all the smaller dies mimic the big one. Common plates may be a good option if you have enough shut height. If not, you can make all of the grab points the same by adding extension blocks to the smaller dies. The purpose is to eliminate unnecessary complexity in grab- bing the dies to move them.
screws, cables/winches, roller chains and rigid-chain systems to move dies, exposing the advantages and
Moving a multi-ton object such as a stamping die is a weighty topic. Stampers can select among several mechanical means for moving dies—with varying advantages and challenges. The most common mechanisms include ball screws, cable/winch rigging, roller chains and rigid-chain systems. Hydraulics often find use for clamping and lifting, but only as a source of rotary horizontal motion. Examining Thrust For moving dies, thrust emanates from equipment either mounted on the press itself or on a provision to which a die is being moved—a die table, die cart, walk-behind unit or bolster extensions. In every case, thrust acts either directly on the die (on-axis) or indirectly below or beside the die (off-axis). The cost of pushing a multi-ton die off-axis can be significant and it’s well worth the effort to quantify. To illustrate, consider an application that requires moving 100,000 lb. on rollers. The standard, average friction is 7%. Under that assumption, 7% of a 100,000-lb. die is 7000 lb. That is the amount of thrust
The force of thrust varies depending on whether it is on- axis or off-axis. Thrust will act either directly on the die (on- axis) or indirectly from below or beside the die (off-axis).
required to move that die along the rolling path. Pushing or pulling with a force of 7000 lb. will move the die for as long as you push or pull it. For off-axis thrust, the plot thickens. You’ll need to consider moment loading—the product of force and distance. These forces develop when thrust is created on one plane and the object being moved resides on another.
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