Forming technology of the hottest cam bush

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Cam bush forming process

Abstract: the process characteristics of cam Bush parts are analyzed, the forming process schemes are compared, and the reasonable forming scheme and die structure are determined, which improves the product quality and prolongs the die life

1 introduction

Figure 1 shows the cam Bush parts on a certain type of engine, and Figure 2 shows its expanded view. The material is a composite of 08F and aluminum, the outer material is 08F, the inner material is aluminum, and the material thickness is 2.5mm. Mass production is required

2 part process analysis

from the part diagram in Figure 1 and the expansion diagram in Figure 2, it can be seen that this part is essentially a circular part composed of semicircle, circular oil hole and J-shaped oil groove, but when the circular ring is formed, its joint is formed by two groups of large and small (a total of 4) circular lap extrusion lap forming, which increases the difficulty of rounding forming. At the same time, in order to meet the product quality requirements after rounding, the outer surface of the part should be ground and the inner surface should be machined. Considering the limitation of material thickness, the cylindricity error of its internal and external surfaces should be reduced as much as possible during the roll forming, so as to improve the production efficiency of subsequent machining processes and reduce the scrap rate

3 analysis of forming process scheme

according to the process characteristics of the part, the difficulty of forming the part is how to coordinate the relationship between each oil groove and the rolling forming process, and how to realize the extrusion and lap during the rolling forming, and strive to reduce the cylindricity error of the rolling forming part

scheme 1 adopts the process scheme of blanking (punching ∮ 8mm semicircular hole at the same time), embossing J-shaped oil groove, rounding (pre bending, second bending, three bending rounding forming), punching ∮ 7mm hole, and mandrel shaping. The test found that there are many stamping processes and the product qualification rate is low in this scheme. The main reason is that punching ∮ 8mm semi-circular hole has an impact on the subsequent rounding forming process, and punching ∮ 7mm hole also has an adverse impact on the previous rounding forming process

scheme 2 adopts the forming process shown in Figure 3, that is, blanking (∮ 8mm semicircular hole does not punch out), stamping, rounding (pre bending, second bending, third bending, rounding), mandrel shaping, milling machine processing ∮ 8mm semicircular hole, drilling machine processing ∮ 7mm hole. This scheme not only solves the shortcomings of scheme 1, but also improves the rolling accuracy, saves equipment investment and improves production efficiency. The test shows that the scheme is reasonable

4 roll forming die structure

after blanking and stamping oil grooves, roll forming becomes a difficult point in the forming process. Three times of bending are used in roll forming to meet the forming requirements

when pre bending, press and bend both sides of the strip into a 1/8 arc of r25mm; During the second bending, bend the pre bent workpiece into a semicircle with r25mm at the bottom, so that both sides form a U shape; During the three bending and rounding forming, the parts after the second bending are directly put into the rounding die, and the joint is tightly formed by extruding and rounding

Figure 4 shows the mold structure of double bending, which is mainly used to test the tensile stress relaxation mechanical properties of metal materials (such as steel strands, PC steel bars and steel wires) at room temperature. Due to the thick material of the part and large bending deformation of the workpiece, preventing bending from springback in prolonging the shelf life of food and ensuring the service life of the die edge have become the biggest difficulties in the die structure design. Using the mold structure in Figure 4, two cylindrical female dies are embedded in the female die insert, and both ends of them are fixed on the female die insert with fixed blocks. This structure successfully solves the above problems

Figure 5 shows the structure of the three bend rounding forming die. The rounding adopts the method with mandrel to ensure the cylindricity of the workpiece during rounding. Before rounding, put the mandrel into the preform after two bends, and then put it into the rounding forming die for rounding, and finally take out the mandrel outside the die

1. Upper mold base "Look at the variable-frequency pump in my hand. 2. Guide sleeve 3. Guide column 4. Female die insert

5. Lower die base 6. Cylindrical die 7. Fixed bolt

8. Fixed stop 9. Female die 10. Male die

11. Male die fixed plate 12. Base plate 1. upper die base 2. Male die base plate 3. Guide sleeve 4.

guide column 5. Male die 6. Male die fixed plate 7. Female die

8. Female die fixed plate 9. Female die base plate 10. female die lower die base

5 conclusion

this forming process scheme successfully solves the problem of parts The problems such as the lap at the joint, the accuracy of the ring and the repair of the die in the use process during the rolling forming have been proved by the actual production (Xiaohong) of the factory that the forming process is reliable and the die structure is reasonable, which is especially of guiding significance for the serial production of cam bush

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