1、 Principle of ultra precision blanking
On the basis of ordinary blanking, strong blank holder ultra precision blanking technology is adopted for the edge of the workpiece. It is a stamping process with small gap under strong blank holder. The principle is to press the gear ring on the guide pressing plate into the metal plate near the edge of the die, and then the blanking force acts on the plate under the pressure of back pressure, so that the material in the edge is squeezed into the cavity of the die under the state of three-dimensional compressive stress, so as to form an ultra-high-precision stamping part.
2、 Advantages of ultra precision blanking
(1) The section is pure shear separation under three-dimensional compressive stress. The stamping equipment improves the main stamping, pressing and ejector forces in three directions at the same time.
(2) The precision of die manufacturing is high and the gap is very small, and high-precision ball guiding device should be adopted.
(3) The edge of punch or die has small rounded corners, so that more material is squeezed into the deformation area to increase the compressive stress.
(4) The blanking process requires high equipment accuracy, die structure, materials and the performance of stamping oil.
3、 Disadvantages of ultra precision blanking
(1) The investment of fine blanking machine is higher, which is more than ten times that of ordinary press.
(2) Fine blanking machine has strong specificity and is not suitable for multi variety and small batch process. It is only feasible after the batch reaches a certain scale.
(3) Fine blanking technology is a relatively new and complex technology. It requires not only advanced fine blanking machines, but also many advanced supporting equipment.
4、 Factors affecting the quality of blanking parts
(1) The plasticity of raw materials of pure metal blanking parts is better than that of alloys. Impurity elements usually cause brittleness and reduce plasticity. Various alloys have different effects on plasticity.
(2) The single-phase structure has better plasticity than multiphase structure, and the properties, shape, size, quantity and distribution of the second phase are different.
(3) The process deformation temperature increases with the increase of temperature in the blanking process, and the plasticity also increases, but this increase is not a simple linear increase.
(4) The increase of strain rate not only reduces the plasticity of metal, but also increases the plasticity of metal. The comprehensive action of these two factors finally determines the change of metal plasticity.
(5) Under the condition of deformation mechanics, in the state of principal stress, the more the number and value of compressive stress, the better the plasticity of metal.
5、 Selection of matching stamping oil
The factors affecting the blanking accuracy and efficiency generally include the accuracy of stamping equipment, the rationality of die design, the quality of stamping die, the performance of stamping oil, etc. How to select stamping oil is also an important topic of stamping technology:
(1) Silicon steel plate: silicon steel plate is a relatively easy material for punching. Generally, in order to make the finished workpiece easy to clean, low viscosity punching oil will be selected on the premise of preventing punching burrs.
(2) Carbon steel plate: when selecting stamping oil for carbon steel plate stamping, we should first pay attention to the viscosity of drawing oil. The better viscosity is determined according to the difficulty of processing, the method of feeding drawing oil and degreasing conditions.
(3) Galvanized steel plate: galvanized steel plate is a welded steel plate with hot-dip or electro galvanized coating on the surface. When selecting stamping oil, attention should be paid to the problem that chlorine stamping oil may cause white rust, while the use of yidaboren sulfur stamping oil can avoid rust, but it should be degreased as soon as possible after stamping.
(4) Copper and aluminum alloy plate: because copper and aluminum have good ductility, when selecting stamping oil, you can choose stamping oil with oily agent and good sliding performance, and avoid adding stamping oil containing chlorine, otherwise the stamping oil will corrode copper and aluminum alloy and blacken its surface.
(5) Stainless steel: stainless steel is easy to produce work hardening material. It is required to use tensile oil with high oil film strength and good sintering resistance. Generally, stamping oil containing sulfur and chlorine compound additives is used to ensure extreme pressure machining performance and avoid problems such as burr and fracture of workpieces.
