This paper focuses on the processing technology of box parts from three aspects: the formulation of technical road, the selection of positioning datum and the processing of primary appearance, puts forward the leading hole finishing technology plan, and points out that the processing accuracy of the primary hole system of box parts has become the key to the processing technology of box parts.
[Key words] technical road planning; Selection of positioning datum; Box plane processing; Internal stress; Hole series processing box parts are typical parts of mechanical parts, such as lathe headstock, gear transmission box, gearbox, etc. they are one of the basic parts of the machine. They adhere to the accurate orientation of the shaft, bearing, sleeve and gear in the machine and components, and make them move harmoniously with each other according to the pre planned transmission connection to form a whole. The assembled box parts are installed on the machine with the planning datum plane of the box. Therefore, the processing quality of the box not only affects its installation accuracy and motion accuracy, but also has a decisive impact on the operation accuracy, service performance and service life of the machine.
1、 Planning of technical road
There are many surfaces of the box that require processing, such as lathe head box, gear transmission box, etc. in these processing surfaces, the plane processing accuracy is easier to ensure than the hole processing accuracy. Therefore, the processing accuracy of the spindle hole (primary hole) and the hole system processing accuracy in the box become key technical problems. Therefore, I prefer to pay attention to several points in the arrangement of the technical road.
(1) Machining sequence from face to hole
Machining the plane first not only cuts off the roughness and sand inclusion on the surface of the blank, but also makes it convenient to scribe and align when machining the holes scattered on the plane, and when the boring cutter starts boring, there will be no impact oscillation and damage to the cutter due to the roughness of the end face. Therefore, it is generally best to machining the plane first.
(2) The rough and finish machining shall be separated
The box structure is disordered, the accuracy of the main surface is high, and the cutting force during rough machining
The clamping force and cutting heat have a great impact on the machining accuracy. If finishing is carried out immediately after rough machining, the internal stress of workpiece deformation caused by various reasons after rough machining is not fully released, which cannot be eliminated in finishing machining, and then the box body deforms after unloading, affecting the final accuracy of the box body. I think in the process of rough machining, It is best to loosen the fixture repeatedly to release the internal stress as soon as possible, so as to ensure the processing quality of the box to a greater extent.
(3) Resolution of process convergence or laxity
The separation during the rough and finish machining of the box conforms to the principle of lax process. However, in order to reduce the number of machine tools and fixtures used and the number of box transfer and installation, the rough and finish machining can be relatively concentrated and placed on the same machine bed as far as possible during the medium and small batch production.
(4) Arrange appropriate heat treatment process
The casting box has disordered structure, uneven wall thickness, inconsistent cooling speed during forging, simple internal stress and hard appearance. Therefore, sandblasting and quenching and tempering personnel shall be reasonably arranged after forging.
ken. tang@chengcg.com
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