Trim dies are commonly used in manufacturing operations to produce lawn mower housings, engine covers and other types of drawn shell components which must be trimmed along the vertical walls of the shell.
A typical trim die used to accomplish the trimming of the peripheral edges of a drawn shell is illustrated in the prior art drawing of FIG. 2. The drawn shell, which is to be trimmed, is positioned on a part locator member 10 that is carried on the top portion of the die's lower section or shoe 12. A stripper plate 14, configured to mate with the part locator member 10 is carried on the upper shoe 16 of the die so that as the press ram 18 is lowered, the drawn shell will be secured between the stripper plate 14 and part locator member 10.
To shear the vertically extending walls of a drawn shell while it is secured between the stripper plate 14 and part locator member 10, the lower die shoe 12 is equipped with a punch 20 that interacts with a trim die ring 22 carried on the upper die section or shoe 16. For the punch 20 to cooperate with the die ring 22 and shear the shell walls, the lower shoe 12 must be shifted laterally and transversely. A trim die press is equipped with the capability to transversely and laterally shift bed or wobble plate 24, upon which is carried the lower die shoe 12.
To enable the part locator member 10 and drawn shell to remain stationary while the lower die shoe 12 is shifted transversely and laterally, the part locator 10 is attached to the press by one or more posts or pillars 26 which pass through openings or channels 28 in the lower die shoe 12 and wobble plate or press bed 24.
Since the posts 26 of the part locator members 10 must pass through the lower die section 12 and wobble plate 24 to be connected to the press, they will project below the bottom plate 30 of the die when it is removed from the press.
While it is generally preferable to first position a die assembly on the bed of a press when installing it, it is necessary to install a trim die by attaching the upper shoe 16 of the die to the press ram 18 first so as to avoid damage to the posts 26 which project below the die.
Typically, installation of a trim die in a press is accomplished through the use of a fork truck. The forks are positioned beneath the die to lift it into place against the ram 18 of the die and then bolt the upper die section or shoe 16 to the press ram 18. Such maneuvering can be very time-consuming, expensive and potentially cause damage to the posts 26, keyways 32 carried on the lower shoe of the die and keys 34 on the press or wobble plate 24.
After attaching the trim die to the ram 18, it is lowered to carefully align the posts or pillars 26 with the openings 28 in the wobble plate 24 and align the keyways 32 carried within the bottom die shoe plate 30 with the keys 34 carried on the wobble plate 24. Since the posts or pillars 26 project from the bottom of the die a greater distance than the keys 34 extend above the wobble plate 24, the posts 26 will contact the wobble plate 24 before the keys 34 engage the keyways 32 in the lower shoe 12 and may incur damage.
Generally, trim die posts or pillars 26 are also equipped with keys 36 on their lower ends which mate with keyways carried in the press in order to lock the posts 26 in a specific orientation relative to the press (see FIG. 3). Damage to those keys 36 can also occur as the die is lowered should the posts 26 not be precisely aligned with the openings in the wobble plate 24 or should foreign material be lodged in the openings or stuck to the posts 26. If foreign material is lodged in the post openings, the post 26 may not seat properly and the part locator member 10 may not be properly seated on the die. Should the locator member 10 not be seated properly, the trim die punch 20 may either not shear the drawn shell wall at all or cut it in the wrong location.
Because trim dies are often moved and positioned by a lift truck, the forks may come into contact with the bottom of the posts 26, occasionally causing damage to the keys 36 carried thereon.
For these reasons, it is desirable to provide a die change structure which eliminates the need to position the forks of a forklift truck beneath the die where they can cause damage to the trim die posts, its keys and/or the keyways of the die, and to further provide a structure for quickly installing and/or changing trim dies which does not require that they be carefully and tediously maneuvered into a position of alignment with the ram of the press before being seated on and secured to the bed of the press.