Stripper-Spring Assemblies (Improved Design)

Cushioning
	A spring assembly in a mold can cushion the parting line to decrease shock and vibration. In operation, this example shows that the spring assembly cushions the shock between the A-plate and the B-plate when the mold is closed. Several spring assemblies may be required depending on the size of the mold and the amount of cushioning required.

Mold Ejector Plate

Spring assemblies in a mold can provide uniform support and spring force for the ejector plate and replace conventional die springs and guided ejection systems. Since the spring assemblies have pre-loaded spring pressure, stop pins or shoulder bolts are not needed. The ejector system can be readily accessed by removing the ejector housing. In operation, this example shows that the spring assemblies are compressed between the ejector plate and the support plate when the mold is opened. When the mold is closed, the spring assemblies push the ejector plate away from the support plate.

Sequencing

A spring assembly in a mold can separate the parting lines in a predetermined sequence. In operation, this example shows that the spring assembly is compressed between the X-plate and the B-plate when the mold is closed. As the mold opens, the spring assembly provides a force to separate the parting line between the X-plate and the B-plate while keeping the other parting lines closed. After the spring assembly is fully extended to its free length, the other parting lines are free to separate. Several spring assemblies may be required to balanced the force and keep the other parting lines closed while the X/B parting line opens.

Longer Travel

Spring assemblies can be stacked end-to-end to provide longer travel and support. This example show two assemblies connected together. The threaded end of the lower assembly’s shoulder-screw is screwed into the upper assembly’s threaded insert. This keeps the two assemblies connected together during operation.

Stamping Die

This stamping die is sometimes called a “bump-die” because the top die shoe does not need to be attached to the press ram during operation. Instead, two 4-inch-long spring assemblies lift the top die shoe off the bottom die shoe during the ram’s upstroke. The stripper plate fits around the punch and is attached to nine 3-inch-long spring assemblies.

Stripper Adnustment

Shim washers can be used to adjust stripper height. The “Before” sketch shows the shim washers installed to adjust the stripper downward when the punch is new (and longer). The “After” sketch shows the shims removed to raise the stripper upward after the punch has been shortened due to sharpening. This adjustment can prevent the spring assemblies from being subjected to excessive deflection when the punch is shorter.