Differential mechanism shell casting process

Abstract

The invention provides a differential mechanism shell casting process which has the benefits that the hot section formation can be avoided, the shrinkage porosity and shrinkage cavity defects are overcome, the quality of castings is ensured, the large surface hardness fluctuation of a planet wheel machining spherical surface in contact with cold iron caused by the use of the cold iron is avoided, and the influence on follow-up machining is small; the drilling procedures are eliminated, and a rough boring-fine boring process is directly adopted, so that the cutting quantity is greatly reduced, and the processing efficiency is improved. The differential mechanism shell casting process comprises the following steps: 1, making a sand core main body (1) by adopting a core making machine, wherein the sand core main body (1) adopts an integral structure with a cast hole sand column (2) for casting a cross-shaped shaft hole in a differential mechanism shell; 2, drying the sand core main body (1) in the step 1; 3, putting the sand core main body (1) dried in the step 2 in upper and lower molds of the differential mechanism shell and then casting the molds according to conventional casting processes; 4, finally, opening the molds to obtain the differential mechanism shell (4) with the cross-shaped shaft hole.

Description

technical field [0001] The invention relates to a casting process for a differential case, in particular to a casting process for the currently popular heavy-duty integral differential case. Background technique [0002] The automotive differential is the main part of the drive axle. Its function is to allow the two half shafts to rotate at different speeds while transmitting power to the two half shafts, so that the wheels on both sides can run at unequal distances in the form of pure rolling as much as possible, and reduce the friction between the tires and the ground. The differential has a very important component, that is, the differential case. The shape of the differential case is determined according to different vehicle models and the structure of the differential. There are left and right cover closed type, light overall open type, heavy integral type and so on. The differential case is the skeleton of differential gears, side gears, cross shafts, etc. The differ...

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Problems solved by technology

[0004] But the applicant of the present invention finds through long-term practice the casting process of above-mentioned heavy-duty monolithic differential case, as attached figure 1 And attached figure 2 The heavy-duty one-piece differential case shown in , which includes the differential case 01 and the shaft hole seat 02, because the cross shaft hole is not cast out, 4 huge thermal joints are formed on the differential case, which brings great pressure to the casting. Come adverse effects, the disadvantages are:

[0005] 1. The shaft hole seat 02 on the differential case 01 has the thickest thickness because there is no cross shaft hole cast there, and there are generally four shaft hole seats 02 on the differential case 01, so when casting 4 huge thermal knots (as attached figure 2 The dotted ring in the center), shrinkage cavity and shrinkage defects are easily formed at the hot joint, which affects the quality of the casting;

[0006] 2. Due to the above-mentioned shrinkage cavity and shrinkage defect at the hot joint, it is easy to drill off the center when drilling the cross-axis hole, which cannot guarantee the shape and position accuracy of the four cross-axis holes, and the drill bit is easily broken. At the same time, the wear of the boring tool is also relatively large. serious;

[0007] 3. Although in the prior art, in order to solve the defects of shrinkage cavity and porosity, since the cross shaft hole is not cast out, try to place four small chills in the inner cavity of the planetary wheel close to the drilled cross shaft hole, although the shrinkage cavity shrinkage is reduced Defects occur, but cannot be solved 100%; on the contrary, due to the placement of the cold iron, the surface hardness of the processed spherical surface of the planetary wheel in contact with the cold iron fluctuates greatly, which affects the subsequent machining

[0008] To sum up, the casting process of the heavy-duty integral differential case in the prior art has hot joints during casting, and shrinkage cavities and shrinkage defects are easily formed at the hot joints, which affects the quality of the castings, and the subsequent drilling process is required , the machining cutting volume is large, and the machining accuracy is low. The cold iron needs to be placed in the shrinkage cavity, which will cause large fluctuations in the surface hardness of the spherical surface of the planetary wheel that is in contact with the cold iron.

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