Agricultural machinery is general name for various mechanical equipment used in agricultural production.It is mainly used in agricultural machinery enginesOur company's agricultural machinery engine valves have the characteristics of high price and high quality compared with other companies.The additional process is usually top soldering, top surfacing, cone surfacing, surface nitriding, surface chrome plating, and the like.
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The idle gear is a key component on the Yellow River-Kawasaki 250 motorcycle. Its material is 20CrMo. The shape and size are as follows. The part has three internal teeth evenly distributed on the inner wall. The tooth length is 20mm, the tooth thickness is 5mm, and the tooth width is 9.5mm. Conventional machining methods produce not only low material utilization rate, but also time-consuming and labor-intensive. Therefore, the extrusion technology is used to make the difficult-to-machine internal tooth part extrusion forming to meet the drawing design requirements, which is an inevitable trend of its production development.
1 Structural process analysis The part is atypical hollow part, the structure is symmetrical and simple. It is suitable for the cold extrusion forming process. The extrusion only requires the coaxiality of O57 to O43 to be less than 0.35mm. The remaining dimensional tolerances are free tolerances and roughness requirements. In general, the cold extrusion process can fully meet the various precision requirements. The extrusion part designed according to the cold extrusion process is as shown in the figure. The forming volume is calculated as the extrusion volume V= 37457.52mm3. The blank diameter is 57-0.1mm, then the blank height should be For the 14. 7mm, the axial margin can be increased by 2~3mm, and the height of the blank is 18mm. According to the inverse extrusion force diagram algorithm, the unit extrusion force can be calculated as 1800MPa. The total extrusion 2 mold structure can be seen from the product parts drawing. The precision of the pressing parts is not very high. There is a certain machining allowance on the upper and lower end faces and the outer circle, and there are also processing requirements on the concentric circles of the claws. Therefore, we use a universal black metal extrusion molding frame.
The working part of the mold for cold extrusion process should have sufficient strength and rigidity. The easy-to-wear part should be easy to assemble and disassemble for easy replacement. In addition, there should be good guiding. On this basis, the mold structure should be as simple as possible, easy to manufacture, and cost. low.
The mold structure diagram we used is as shown in the punch 3 and the punch sleeve 2 with interference fit, relying on the mold structure to calculate the interference to maintain the punch positioning 1-bearing pad; 2 punch sleeve; 3 convex When assembling the die punch, firstly, the punch sleeve 4 and the die die; 5 top piece; the 6-pole seat is heated to about 300 ° C, and then the punch is pressed into the punch sleeve. When the combined die 4 is assembled and debugged by a typical three-layer prestressed structure mold, in order to ensure that the punch and the die are concentric, a concentric sleeve of the car should be positioned between the punch and the die. In operation, the punch is descended to the male die sleeve 2 to contact the combined die 4 to complete the axial positioning.
3 Process and its effect The process flow of the idle gear is as follows: preparation material - softening heat treatment + blanking of the blank car - phosphating saponification + cold extrusion forming - stress relief tempering - machining with cold extrusion process to produce large idle gear Mass production inspection proves: the product size is stable, the surface is smooth; the mold structure is simple, the manufacturing precision is easy to guarantee: 2000-08-15 pressure
