Technical problems and solutions for metal stamping processing of micro-holes

The definition of tiny holes at home and abroad is: holes with a diameter of 0.1-1.0 ram are called small holes, and holes with a diameter of less than 01 mm are called micro holes. The development trend of the application of filters used in internal combustion engine fuel nozzles is also roughly the same. Therefore, the requirements for small hole punching processing are getting higher and higher.
At present, the definition of micro-holes at home and abroad is: holes with a diameter of 0.1-1.0 ram are called small holes, and holes with a diameter of less than 01 mm are called micro-holes. With the emerging microelectronics industry, micro-machines and micro-electromechanical systems With the rapid development of industry, more and more parts with micro-holes as the key structure are used, the pore size is getting smaller and smaller, and the precision requirements are getting higher and higher. For example, cooling holes of aero-engine turbine blades, jewel bearing holes, electron microscope gratings, PCB microporous plates, polymer composite holes, diamond drawing dies, precision chemical fiber spinnerets, RP technology rapid prototyping equipment nozzle holes, optical fiber connectors, fuel The fine structure of high-end products such as fuel injection nozzles, printer inkjet holes, red blood cell filters, and micro-jets and micro-pumps. The workpiece materials of these products are mostly metal alloy materials, with a large aspect ratio of the micro-holes, and the characteristic size is between 50 and 100 ppm.
For the processing of micro-holes, due to the development of workpiece materials towards high strength and high hardness, many parts need to use difficult-to-machine materials such as heat-resistant steel, stainless steel, die steel, cemented carbide, ceramics, diamond and other polymer composite materials. In addition, the shape of the tiny holes is no longer a single circle, but tends to various complex shapes that can achieve specific functions, such as the three-leaf arc, the three-leaf edge, and the v-shaped spinneret. , Hexagonal and other special-shaped holes, these all put forward higher and newer requirements for the processing technology of micro-holes. Specifically, the miniaturization industry requires the processing technology to meet the characteristics of high-volume, high-efficiency, high-precision, high-density, short-cycle, low-cost, pollution-free, and net forming. In the traditional macro-manufacturing field, the plastic forming process ( Blanking, bending, drawing, deep drawing, superplastic extrusion, undulation, embossing, etc.) precisely possess these industrial advantages. Micro-stamping is a key process method in micro-plastic forming technology. This article is aimed at the processing of micro-shaped holes and studies the micro-stamping process from the development of processing equipment.
In the manufacturing industry, the diameter of the drill bit for micro-hole processing is generally φ=0.27 or more. The tool material is Japanese imported tungsten steel or white steel. In the past, due to the high etching processing cost and poor laser accuracy, as the metal small hole punching process improves, It has been basically eliminated. Stable realization of mass production. With the increase in the functions of mobile phones, the distribution of printed circuit boards has become increasingly dense, and the diameter of the micro-holes of the copper foil on the circuit boards has also become smaller, and the processing difficulty has further increased. The application development trend of the filter screen used in the fuel nozzle of the internal combustion engine is also roughly the same, so the requirements for the punching of small holes are getting higher and higher.
There are many reasons why the punching needle is easy to break. It may be the cause of the punching needle itself, or the design defect of the mold. It may also be a series of problems such as the blanking material and so on. In fact, no matter what the problem is, we should solve the problem. The specific methods are similar to each factory. Foreign precision molds are generally loose, and the stripper plate is very tight. The material plate and die must be inlaid with guide posts and guide sleeves. The wire cutting uses slow wire or oil cutting. The male splint is 0.02~0.06mm on both sides, and the stripper is 0.01mm on both sides or even tightly matched. Domestic practices are somewhat different. Generally, the unilateral tolerance of the male splint is ±5μ, and the single side of the stripper is 0.01mm; when using slow wire walking, you can consider increasing it appropriately. If the punching needle is offset, if you want to make the punching needle as short as possible, the gap should be appropriate, the guide post should be larger, and the gap between the guide sleeve of the die and the die should not exceed 0.005mm on one side. The clearance of the stripper plate is smaller than that of the lower template, generally 0.005mm on both sides and 0.02mm on both sides of the male splint. The loose point does not matter. The punch should not be knocked in by force, just push it in by hand.

Post time: Apr-19-2021
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