Precautions For Template Design

The main templates of the continuous mold include punch fixing plate, press plate, concave template, etc. The structural design of the continuous mold has the following three forms according to the accuracy of the stamping products, the production quantity, the processing equipment and methods of the mold, and the maintenance methods of the mold: (1) integral type, (2) yoke type, and (3) inlay type.
1. Block type
The integral formwork is also called integral construction, and its processing shape must be closed. The monolithic template is mainly used for the mold with simple structure or low accuracy. Its processing method is mainly cutting (without heat treatment). The template with heat treatment must be subject to wire cutting or electric discharge machining and grinding. In the case of long template size (continuous mold), two or more pieces will be used together.
2. Yoke type
The central part of the yoke template is processed into a concave groove to assemble the block. Its structure depends on the application requirements, and the concave part can be formed by other templates. The advantages of this yoke formwork structure are: easy processing of the groove, adjustable width of the groove, good processing accuracy, etc. However, low rigidity is its disadvantage.
The design considerations of yoke formwork are as follows:
(1) The chimerism of the yoke plate component and the block part adopts the middle fit or light fit mode. If the strong pressure fit is adopted, the yoke plate will change.
(2) The yoke plate is also used to maintain the block parts. In order to withstand the side pressure and surface pressure of the block parts, it must have sufficient rigidity. In addition, in order to make the groove part of the yoke plate closely combined with the block part, the groove corner of the yoke plate shall be processed as an escape gap. If the groove corner of the yoke plate cannot be processed as an escape gap, the block part must be processed as an escape gap.
(3) The internal shape of the block parts shall be considered at the same time for the division, and the datum plane must be defined. In order to avoid deformation during stamping, the shape of each block part should also be noted.
(4) When the yoke plate is assembled with many pieces of block parts, the pitch changes due to the accumulated processing error of each block part. The solution is to design the middle block part in an adjustable way.
(5) The block parts adopt the mold structure of side-by-side combination. Because the block parts will bear the side pressure during the punching process, resulting in the gap between the block parts or the inclination of the block parts. This phenomenon is an important reason for poor stamping, such as poor stamping size and chip blocking, so adequate countermeasures must be taken.
(6) According to the size and shape of the block parts in the yoke plate, there are five ways to fix them: A. fix them with locking screws, B. fix them with keys, C. fix them with "a" key, D. fix them with shoulders, and E. press and fix them above (such as guide plate).
3. Embedded type
The circular or square concave part is processed in the template, and the block parts are embedded in the template. This template is called the inlay structure. The processing cumulative tolerance of this structure is small, the rigidity is high, and the precision reproducibility of decomposition and assembly is good. Due to the advantages of easy machining, machining accuracy determined by working machinery, and few final adjustment projects, the embedded template structure has become the mainstream of precision stamping dies, but its disadvantage is the need for high-precision hole processing machines.
When the continuous stamping die is constructed with this template, the empty station is designed to make the template have high rigidity requirements. Precautions for the construction of embedded formwork are as follows:
(1) Processing of embedded holes: vertical milling machine (or jig milling machine), integrated processing machine, jig boring machine, jig grinding machine, wire cutting discharge machining machine, etc. For the machining benchmark embedded in the hole, when using the WEDM machine, in order to improve its machining accuracy, it is necessary to carry out two or more WEDM machining.
(2) Fixing method of embedded parts: The decisive factors of the fixing method of embedded parts include the accuracy of machining, the ease of assembly and disassembly, and the possibility of adjustment. There are four ways to fix the insert: A. fix it with screws, B. fix it with shoulders, C. fix it with toe blocks, and D. press the upper part with plates. The fixing method of the embedded part of the concave formwork is also press fit. At this time, the relaxation result caused by processing thermal expansion should be avoided. When using the circular mold sleeve insert to process the irregular hole, the rotation prevention method should be designed.
(3) Consideration of assembly and disassembly of embedded parts: the machining accuracy of embedded parts and their holes is required to be high for assembly operation. In order to obtain that even slight dimensional errors can be adjusted during assembly, the countermeasures should be considered in advance. The specific considerations for the processing of embedded parts include the following five items: A. A press-in guide part is provided, B. The press-in state and correct position of the embedded parts are adjusted with spacers, C. The bottom surface of the embedded parts is provided with a hole for pressing out, D. When locking with screws, the same size of screws should be used to facilitate locking and loosening, E. To prevent errors in the assembly direction, Anti-dazzle chamfering shall be designed.