Problems that Machining Center Should Pay Attention to when Processing Composite Materials
The machining center is a highly-accurate high-precision machining facility for automated machining. Its entire machining process is completed under the control of a CNC system. It can process some very unique composite materials. Nowadays, the composite materials are widely used in our lives. In all aspects, especially the aerospace industry, some ultra-precise machinery industries. Here's a brief introduction to some of the issues that the machining center should pay attention to when processing composite materials:
First, the type of processing center composite materials
Composite materials are divided into metal and metal composite materials, non-metal and metal composite materials, non-metal and non-metal composite materials according to their composition. According to its structural characteristics, it is divided into:
1, fiber composite materials. The various fiber reinforcements are composited in matrix material. Such as fiber reinforced plastic, fiber reinforced metal and so on.
2. Sandwich composites. Composed of different surface materials and core materials. Usually the face material has high strength and thinness; the core material is light and has low strength, but has a certain rigidity and thickness. Divided into solid sandwich and honeycomb sandwich two.
3, fine-grained composite materials. The hard fine particles are evenly distributed in the matrix, such as dispersion-strengthened alloys, cermets, and the like.
4, hybrid composite materials. It consists of two or more reinforcing phase materials mixed in one matrix phase material. Compared with ordinary single-reinforced composite materials, the impact strength, fatigue strength and fracture toughness are significantly improved, and have special thermal expansion properties. Divided into layers mixed, mixed layers, mixed sandwiches, intra layer/interlayer mixing and super-hybrid composite materials.
Second, the processing center when processing composite materials should pay attention to the problem 1, carbon fiber composite material layer strength is low, easy to produce under the action of cutting force delamination, so drilling or trimming should reduce the axial force. Drilling requires high rotation speed and small feed. The machining center rotates at a speed of 3000~6000r/min, and the feed rate reaches 0.01~0.04mm/r. The drill adopts a three-point two-flute or two-point two-flute in a better form. The sharp knife The tip can be cut off by the carbon fiber layer firstly, and the two edges can repair the hole wall. The diamond-incorporated drill bit has excellent sharpness and wear resistance. The drilling of composite materials and titanium alloy sandwiches is a difficult problem. Generally, solid carbide drills are used, and the drilling parameters are drilled according to the cutting parameters of the titanium alloy drilled. The drill is drilled from the titanium alloy side until it is drilled and the lubricant is added during drilling. Ease composite burns. Boeing specially developed a PCD drill bit for the drilling of interlayers.
2 and 3 types of new solid carbide composite cutters have better cutting results. They all have some common features: high rigidity, small helix angle, even 0°, specially designed herringbone blades, all can be effective Reduce the axial cutting force of the machining center, reduce the delamination, and its processing efficiency and effect are very good.
3. The composite material cuttings are in powder form, which poses a great harm to human health. A high-power vacuum cleaner should be used to collect dust. Water cooling can also effectively reduce dust pollution.
4. Carbon fiber composite materials generally have large size, complex shape and structure, high hardness and strength, and are difficult to process. In the cutting process, the cutting force is relatively large, the cutting heat is not easily transmitted, and the resin is burned or softened in severe cases, and the tool wears seriously. Therefore, the tool is the key to carbon fiber processing, and the cutting mechanism is closer to grinding rather than milling. The cutting line speed of the machining center is usually more than 500m/min, adopting a small feedrate strategy of high speed. Cutting edge processing tools generally use solid carbide knurling cutters, electroplated diamond particles, diamond cutters, copper diamond saw blades.
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