The die for press work is made of a top die and a bottom die. If the relationship between the top die and the bottom die is not correct, either the press work cannot be made properly or repairs will become necessary early on. This relationship is created by what are called guides. Such guides are called die matching guides or cutting edge matching guides. The well known form of such a guide is a die set. However, a die set is one form of a cutting edge matching guide. The various forms of guides are explained below while referring to the figures.

Structure of Dies: Change in Die Structure Depending on the Guides

(1) Structure without a guide

Although is it may appear strange that this structure appears in the explanation of guides, there are dies with a structure in which the relationship with the die is created directly by the punch. Further, this structure shows the basic form of a die. Guides are secondary structures. Because of the presence of guides, it becomes easy to install the die in the pressing machine, or the assembly of the die becomes easy, or the accuracy during press operation (the dynamic accuracy) becomes better. The die can be used even if there are no guides and the pressing work can be carried out.

(2) Outer guide structure (die set structure)

This is the most basic guide structure. This was developed for the purpose of making the assembly of the die and the installation of the die in the pressing machine easy. This structure is called the outer guide structure because the guiding is done on the outer side of the plate. The relationship between the punch and the die is established by a coupling using a dowel pin (knock pin). The accuracy of the relationship between the punch and the die is determined by how the dowel pin is inserted.

(3) Additional inner guide structure

This is a structure that is a die set structure to which an inner guide (sub-guide) has been added. A guide that is inside the plate and guides the movement of the die relative to the punch is called an inner guide. The inner guide restricts the movement of the stripper plate and increases the accuracy. The inner guide determines the relationship between the punch and the die. The accuracy increases because the relationship between the punch and the die is maintained without needing a coupling through a dowel pin. On the other hand, it is difficult to manufacture. Since a dowel pin is present in this structure, there may be problems due to interference between the outer guide and the inner guide.

(4) Structure without a dowel pin

Interference with the dowel pin may occur if an inner guide is added to a die set structure. In order to avoid this interference, it is better to remove the dowel pin, and hence this is a structure in which the top or the bottom dowel pin has been removed. It is very common to remove the dowel pin from the top die.

(5) Inner guide structure

A guide is a part that establishes the relationship between the punch and the die. A dual structure is one in which the guiding is done by both an outer guide and an inner guide. The inner guide structure is one in which there is only one guide that is the inner guide that can guide directly while eliminating the outer guide. This structure is suitable for small dies. In a large guide, separating the top and the bottom is very difficult.

(Additional) Quick die change unit

There is a quick die change unit that is used in single preparation stage, etc. This structure can be considered to be one in which only the inside of the die set of the die is a unit that is exchanged. Since a dowel pin having some looseness is used, it cannot be used for dies with small clearances (but can be used if there is an inner guide).

A guide does not function completely if it is only put there for the sake of its form. Guides should be used considering the accuracy of the die and the purpose of using the guides.