The application of large-scale iron plate processing stainless steel shows that the mold working in the chemical corrosive environment must have corrosion resistance, and also requires certain hardness, strength and wear resistance. The common martensitic stainless steels are 2Cr13, 3Cr13, 4Cr13, 3cr17mo, 9Cr18, 9Cr18Mo, cr14mo4v, 1Cr17Ni2, etc. According to the requirements of hardness, several kinds of stainless steels are introduced as follows: 1. The application of medium carbon high chromium corrosion-resistant martensitic stainless steel requires a hardness of about 50-55hrc. The typical stainless steel is 4Cr13, which is medium carbon martensitic stainless steel. After heat treatment, it has high hardness and wear resistance, and is resistant to atmospheric and steam corrosion. It can be used to manufacture plastic mold with certain corrosion resistance. The quenching temperature of the steel is generally 1050 ℃, and the steel has good hardenability. For small plastic molds, air cooling can be used to reduce the heat treatment deformation of the mold; while oil quenching can be used for the large-size mold. The quenched mold is generally tempered at 200-300 ℃, and the hardness after tempering is 50-53hrc. Suitable for manufacturing moulds of plastic products under contractor’s load, high wear resistance and corrosive medium. 2. In the application of high carbon and high chromium stainless steel, high carbon and high chromium stainless steel, such as 9Cr18, cr18mov, cr14mo, cr14mov, can be selected for the corrosion-resistant plastic mold with high hardness and high wear resistance. Taking cr14mov as an example, the carbon content of cr14mov is 1.0% – 1.15%. The steel has good hardenability. The quenching temperature is 1100-1120 ℃, the hardness is more than or equal to 58 HRC, the tempering temperature is 500 ℃, the holding time is 2 h, and the tempering time is 4 times. The hardness of cr14mov steel is greater than or equal to 60 HRC. The steel has high hardness, high wear resistance, good corrosion resistance, and high temperature hardness. It is suitable for manufacturing plastic mold with high load and high wear resistance under the action of corrosive medium. 3. Application of low carbon Cr Ni corrosion resistant stainless steel 1Cr17Ni2 steel belongs to martensitic stainless steel, which has good corrosion resistance to oxygen acids (nitric acid at a certain temperature and concentration, most of organic acids) and salt aqueous solutions; the steel has higher strength and appropriate hardness, but its performance is better than 4Cr13 steel. Therefore, some plastic molds with high corrosion resistance are still made of this type of stainless steel. The quenching temperature range of 1Cr17Ni2 steel is 950-1050 ℃. After quenching, the hardness of steel is 38-40hrc after tempering at 200-300 ℃. If the austenite is transformed into martensite, the hardness can be increased to 42-48hrc. The strength, hardness, wear resistance and corrosion resistance of the steel are higher. The tempering temperature is 600-700 ℃, and the basic structure of the steel is tempered sorbite, which has good combination of strength and toughness and high corrosion resistance. This kind of steel can also be nitrided to improve the wear resistance, anti bite ability and the service life of the die.
According to the parts, quantity and accuracy requirements, the charging method is as follows: 1. General materials for drilling and processing; 2.5 times of the diameter; 2.5 times of the diameter; 0.05; 0.12; 0.12; 0.12 For small holes not less than 0.5 yuan), the basic price * depth diameter ratio * 0.4 shall be charged for general materials with the depth diameter ratio greater than 2.5, the base price * 5 shall be charged for the hole diameter accuracy requirement less than 0.1 mm or the center distance requirement less than 0.1 mm; the tapping charge standard shall be charged according to the tap diameter * 0.2 (with cast iron as the standard, and steel parts with an additional * 1.2) shall be charged at the standard base price * 0.2-0.8 during batch processing (according to the batch size and addition) Ease of work) Computer gong processing, mechanical parts processing, CNC machine tool processing, Dongguan high speed computer gong processing lathe, general precision optical axis machining, for small length diameter ratio and 10, it is charged according to the blank size * 0.2 (the minimum is 5 yuan) ﹥ if the length diameter ratio is greater than 10, it will be charged according to the general optical axis base price * length diameter ratio * 0.15, or the precision requirement is within 0.05mm or the taper is required to be charged by the general optical axis base price * 2 The general step shaft (fan shaft, pump shaft, reducer shaft, grinding wheel shaft, motor shaft, spindle, etc.) is charged at the basic price * 2 for general precision smooth shaft processing, or * 3 for the step shaft with taper, inner and outer rib, or for general-purpose screw, it is processed according to the general precision optical axis Base price * 4 charge the general flange parts according to the material diameter * 0.07, and the diameter greater than 430mm is charged according to the material diameter * 0.12. \General round nut parts are charged according to diameter * 0.25 (including materials) generally trapezoidal, triangle nut parts are charged by diameter * 0.3 (excluding materials); (general shaft sleeve parts (diameter less than 100, diameter length ratio less than 2) are charged by material outer diameter * 0.2, and those with diameter length ratio more than 2 are charged according to diameter length ratio * base price * 0.6. Generally repair bearing platform parts with wear loss less than 2mm, diameter less than 40mm and width less than 25m M each 5 yuan, need to be on the central shelf, or the length of more than 1.7 meters of the base price * 2 charge. If the diameter is greater than 40mm, it shall be charged according to the diameter * 0.2. \For milling machine processing, general keyway processing (length width ratio less than 10) keyway width * 0.5 (minimum 5 yuan). If the aspect ratio exceeds 10, it shall be charged according to the aspect ratio * base price * 0.1. If there is strict position requirement, it will be charged according to the base price * 2. Processing of materials with hardness greater than hrc40
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