New technology for sheet metal forming - precision punching
Precision punching technology is an advanced precision forming technology that uses metal sheets as raw materials and adopts a plastic processing method with minimal and no cutting. With one forming, parts with high dimensional accuracy and low shear surface roughness can be obtained. At present, precision punching is divided into ordinary precision punching, strong pressure plate precision punching, opposite convex concave die precision punching, reciprocating punching, synchronous shear extrusion precision punching, closed extrusion precision punching, etc.
1. The principle of precision flushing
First, press the V-shaped gear ring on the pressure plate into the metal plate near the concave die edge. Then, under the condition of reverse pressure, the punching force acts on the plate. At this time, the material near the edge is always in a three-dimensional compressive stress state, thereby improving the plasticity of the material and preventing cracks or crack propagation in the punching cutting surface from causing the shear surface to break. Finally, the material is punched along the shape of the concave die edge in a pure shear form.
2. Precision punching material
About 80% of precision punched parts are made of steel, while the rest are made of materials such as copper and copper alloys, as well as aluminum and aluminum alloys. Steel not only includes low-carbon steel, but also high carbon steel, alloy steel, stainless steel, tool steel, and high-strength microalloyed fine grain steel. Precision punched steel should have good mechanical properties and significant deformation capacity. Generally, a carbon content of no more than 0.35%, a tensile strength of no more than 650N/mm2, and a yield strength ratio of approximately 60% are most suitable. For medium and high carbon steel and alloy steel, the carbide spheroidization rate of precision punching materials should be above 90% and evenly distributed.
3. Precision punching mold
Precision punching mold is an important means to achieve precision punching, which directly affects the quality of precision punching. The mold system is divided into convex mode system and fixed convex mode system. In actual production, the fixed convex mode mold (80%) is about four times that of the movable convex mode mold (20%). According to the type of mold, it can be divided into simple precision stamping dies, compound precision stamping dies, continuous precision stamping dies, continuous composite precision stamping dies, and conveying precision stamping dies. Continuous composite film (72%) is widely used in actual production to achieve multi station composite forming processing of workpieces, reducing punching times and improving efficiency.
Precision punching has the characteristics of no cutting and high plastic processing, and will be applied in more and more industries.