Analysis of the processing process of box-type spare parts
This paper analyzes the processing technology of the box parts from the formulation of the process route, the selection of the positioning benchmark and the processing of the main surface, and points out that the processing accuracy of the important hole system of the box parts becomes the key of the processing technology of the box parts.
[Key words] process route formulation; positioning reference selection; box plane processing; internal stress; hole system processing
Box parts is a typical parts of mechanical parts, such as lathe bedside box, gear box, transmission box body, etc., is one of the basic parts of the machine, it will be the machine and parts of the shaft, bearing, sets and gear parts each keep the correct position, and according to the design transmission relationship to make its coordinated mutual movement, combined into a whole. After assembly, the box parts and the design reference plane are installed on the machine, so the processing quality of the box not only affects the assembly accuracy and motion accuracy, but also has a decisive impact on the working accuracy, service performance and life of the machine.
1. Design of the process route
Box requirements processing surface of a lot, such as lathe bedside box, gear transmission box in these processing surface, plane processing accuracy than hole, so the main hole in the box hole (main hole) processing accuracy, hole processing precision has become a key problem, therefore, in the arrangement of the process route I tend to pay more attention to some points.
(1) The processing sequence of the first surface and then the hole
First processing plane, not only remove the rough surface uneven and surface sand, more important is in the processing distribution in the plane, marking, is convenient, and when the boring tool began boring, not because the end surface has uneven impact vibration, damage tool, therefore, generally should first processing plane.
(2) Crude and finishing stage should be separated
The box structure is complex, the accuracy of the main surface is high, and the cutting force generated by rough machining is high
Clamping force and cutting heat have great influence on processing accuracy, if rough machining immediately finishing, then the workpiece deformation caused by various reasons of internal stress is not fully released, cannot be eliminated in finishing, resulting in the deformation of the box of the accuracy, I think in the rough machining, should release clamp for many times, the internal stress timely release as much as possible, more limit the processing quality of the box.
(3) The decision of process concentration or dispersion
The separation of the box thick and finishing stage is in line with the principle of process dispersion, but in the medium and small batch production, in order to reduce the number of machine tools and fixtures, and reduce the handling and installation times of the box, the rough and finishing stage can be relatively concentrated, as far as possible on the same machine tool.
(4) Arrange the appropriate heat treatment process
The casting box structure is complex, the wall thickness is uneven, the cooling speed is inconsistent, easy to produce internal stress, and the surface is hard, therefore, the sandblasting should be reasonably arranged after casting
In the process of making the high temperature flange, if the forging process is improper, so there will also be a large or uneven grain, hardening crack phenomenon, the forging cost is higher than the casting flange. The forging can withstand higher shear and tensile forces than the casting.
The advantage of high temperature flange can make a more complex shape, the cost of the whole product is relatively low, the forging advantage lies in the internal organization uniform, there is no casting in the casting, inclusion and other harmful defects, from the production process difference casting flange and forging flange, such as centrifugal flange belongs to a kind of casting flange.
