Modern rapid manufacturing mold technology (2)
2.1.3 laser powder selective sintering technology (SLS)
sls technology is to layer the three-dimensional model of the computer through the layered software. Under the control of the computer, the laser beam will scan the powder layer by layer according to the layered slice section information. The scanned powder will be sintered and solidified (polymerization, sintering, bonding, chemical reaction, etc.), stacked layer by layer, and stacked into three-dimensional solid parts. Error caused by the host part
the biggest feature of this technology is that it can manufacture a part with several different materials (polycarbonate, polyethylene chloride, paraffin, nylon, ABS, casting sand) at the same time.? 2.1.4 fused deposition molding (FDM)
fdm technology is to control the nozzle of extruding molten material by computer. According to the geometric information determined by the CAD product model layering software, the extruded semi flowing thermoplastic material is deposited and solidified into an accurate thin layer of the actual workpiece, and stacked layer by layer from bottom to top into a three-dimensional entity, which can be directly used as a mold or product
2.1.5 three dimensional printing molding technology (3d-p)
3d-p technology uses a microcomputer to control a continuous inkjet printing head, and selectively deposits liquid bonding materials on the powder layer layer by layer according to the layered software. Finally, the two-dimensional layers printed in sequence are stacked into a three-dimensional entity, just like the rapid modeling technology without laser. This technology is mainly applied to porous ceramic preforms of metal ceramic composites. Its goal is to directly produce molds or functional products from CAD product models
2.2 surface molding technology
surface molding technology is a technology that mainly uses new process methods such as spraying, electroforming, chemical corrosion and so on to form cavity surface and fine patterns. Practical applications include the following types
2.2.1 arc spraying molding technology
the principle of arc spraying forming technology is: use the heat of the arc generated between the two energized metal wires to melt the metal wires, rely on high-pressure gas to fully atomize them, and give certain kinetic energy, spray them on the surface of the sample mold at high speed, inlay them layer by layer, and form a metal shell, that is, the inner surface of the cavity, Then, people are willing to use a new type of degradable material with slightly higher price (usually the composite of metal powder and resin) for support and reinforcement to improve its strength and rigidity in order to protect the environment, and combine it with the metal mold base to form a mold
this molding technology has the advantages of simple process, low cost, very short manufacturing cycle, forming the cavity surface only takes a few hours, saving energy and metal materials. Generally, the cavity surface is only mm thick, with strong simulation, and the pattern accuracy can reach 0.5 m
at present, this technology is widely used in the blow molding, Blister molding, PVC injection, PU foaming and various injection molding molds of various polyurethane products with complex surface shapes and fine patterns, such as aircraft, automobile interior trim molds, household appliances and furniture. The loading speed valve should be manually controlled to control the rising speed of the piston (the speed and safety valve are in one body), shoe making, art crafts and so on
2.2.2 electroforming technology
the principle of electroforming technology is the same as electroplating. It is based on the sample mold (ready-made products or master mold made according to product drawings) (cathode), placed in the electroforming solution (anode), so that the metal ions in the electroforming solution are reduced and deposited on the sample mold layer by layer to form a metal shell. After stripping, the surface in contact with the sample mold is the surface of the mold cavity
the main features of this technology are material saving, short mold manufacturing cycle, electroforming layer hardness up to 40HRC, improved wear resistance and life, roughness, dimensional accuracy and sample mold are completely consistent, suitable for injection, blister, blow molding, plastic lining, bakelite mold, glass mold, die-casting mold and other mold cavities and EDM electrode manufacturing.? 2.2.3 etching technology for fine pattern forming on cavity surface
etching technology is a technology of comprehensive application of optics, chemistry and machining. Its basic principle is to make the pattern into film first, and then copy the pattern on the film on the surface of the mold cavity coated with photosensitive materials. After chemical treatment, the surface of the mold cavity forms a protective layer of the part that is not etched, and then select the corresponding etching process according to the mold material to etch the pattern on the inner surface of the mold.? The main characteristics of this technology are short time and low cost. Repairing the damaged pattern can be seamless
2.3 casting molding technology
the common feature of casting molding technology is that according to the sample, convex and concave molds are cast, and the cavity surface does not need machining. There are mainly the following types in actual mold making
2.3.1 bismuth tin alloy molding technology
Bi Sn alloy rapid molding technology is a technology that takes Bi Sn binary eutectic alloy (melting point 138 ℃, expansion and contraction rate 3/10000) as the material and has the method of precision casting to cast punch, concave mold and blank holder at the same time. The technology is characterized by low molding cost, reusable alloy, short manufacturing cycle, high dimensional accuracy, shape and size are completely consistent with the sample, and the life of one-time mold can reach pieces. It is very suitable for new product development, process verification, sample trial production and small and medium-sized batch peace
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