The Importance of Die and Punch Assembly

In order to prevent scoring or marking of the sheet material or other workpiece being punched, a multiple punch and multiple die assembly has a workpiece protector consisting of a punch lifter that is operationally associated with each punch. This lifter supports each punch in an inactive position as an active punch is moved by the ram to the active, i.e. operating position.

 A manually moveable retainer on the die and punch assembly is provided that may be changed by hand between a punch-releasing and punch-retaining position for holding the punches within the multi-punch assembly during operation. This eliminates the requirement for hand tools and manual assembly or disassembly. 

Support for each die is divided between two independent die components, decreasing impact stress on the carrier as the ram drives the punch through the workpiece and preventing stress fractures that previously occurred in die carriers.

 Installing an Actuator-Punch Assembly With A Forming Die

One or more hydraulic actuator assemblies installed directly in one of the die shoes of a forming die set allow for the execution of a predetermined piercing pattern during the formation of the workpiece. Each actuator die and punch assembly has a compact self-contained actuator with supply and return connections through the end cap of the cylinder housing and a return flow path through a tube that extends through the piston. The piston, piston rod, and punch retainer are all slid able in different sections of the housing bore.

The piston rod extends through a punch retainer at one end and an annular rod gland member that is positioned in the cylinder housing bore at the other. A portion of the cylinder housing bore allows for sliding of the punch retainer. An incremental flow back to the reservoir is established by a purging system that uses a check valve in the supply line to eliminate air bubbles. The punch assembly actuator is run by an accumulator with a charge volume detector. 

Why the right Die Clearance is Important 

Die clearance, one of the most crucial characteristics of when it comes to product quality, is the distance between the cutting edges of the die and punch assembly. You must pay close attention to ensure that you get the die clearance right the first time since the difference between suitable die clearance and inadequate or excessive die clearance is very obvious. 

 

1. Proper Clearance

There will be very little rollover deformation and burr when you obtain sufficient die clearance. The hole will be made neatly and precisely, with the bottom two thirds measuring the inside diameter of the die, and the top third reflecting the size of the punch. 

 

2. Insufficient Clearance 

Due to the necessity for more tonnage and the increased stripping force needed when the punch is released due to the hole grabbing the punch, insufficient space might wear down your punch. It takes a secondary shear on the material when the fracture lines of the die and punch assembly do not meet in order to correctly make a hole; this can put a lot of stress on your punch. 

 

3. Excessive Clearance 

More distortion and damage to the material results from excessive clearance than from the tools. Material rollover and burr on the bottom side of the material are the main issues, even though it can wear down the punch's edge. This is as a result of the much higher angle between the burnish zone and the fracture plane.

In either case, improper die clearance will drastically shorten tool life. The greatest approach to understand the ins and outs of metal stamping and how to achieve the optimal outcomes is through trial and error. Until you find it out, keep experimenting with different approaches and avoid utilizing new, pricey instruments. Different materials might call for different applications. 

Conclusion

A hole with a small rollover and sharp fracture is created by insufficient clearance, and the profile is essentially perpendicular to the material's surface. Tool life is decreased by too-small clearance.

Understanding the configuration and components of the die and punch assembly is required before developing the press tool for the sheet metal stamping process. The press tool is made up of a variety of parts, including ejectors, backup plates, strippers, punches, and dies.