Fault analysis: after measuring the workpiece, it is found that the relative positions of all dimensions of the parts are correct, but all the coordinate values of X axis are different by 10 mm. By analyzing the causes, the whole pitch deviation of x-axis dimension (the pitch of this axis is 10 mm) is caused by the offset of reference point position.
For most systems, the reference point is generally set on the “zero pulse” of the first programmer after the release of the deceleration iron at the reference point; if the reference point deceleration block is released, the encoder happens to be near the zero pulse, and due to the random error of the deceleration switch action, the reference point position may be shifted by one whole pitch. This fault is especially easy to happen when using small pitch ball screw.
Troubleshooting: for this kind of fault, as long as the position of the deceleration stop at the reference point is readjusted so that the difference between the release point of the stop and the “zero pulse” position is about half a pitch, the machine can resume normal operation. After the above treatment, the fault is removed and the machine returns to normal operation. After the above treatment, the trouble is eliminated, the machine tool returns to normal, and all parts are processed normally.
1、 Machine parts processing plant – types of mechanical parts:
The first type is mainly used in precision machinery, which has high requirements for the stability of the fit. It requires that the wear limit of the parts should not exceed 10% of the dimensional tolerance value of the parts in the process of use or after many times of assembly. This is mainly applied to the surfaces of precision instruments, meters, precision measuring tools, and friction surfaces of extremely important parts, such as the inner surface of cylinder, the main journal of precision machine tools, and the coordinate boring machine Main journal, etc.
The second type is mainly used in ordinary precision machinery, which requires high stability of fit. The wear limit of parts shall not exceed 25% of the dimensional tolerance value of the parts. It is mainly used in machine tools, tools, surfaces matching with rolling bearings, taper pin holes, and contact surfaces with higher relative speed, such as the mating surfaces of sliding bearings and gears Gear tooth working face, etc.
The third category is mainly used in general machinery, which requires that the wear limit of mechanical parts shall not exceed 50% of the dimensional tolerance value. The contact surfaces of parts without relative movement, such as box cover and sleeve, shall be close to each other, the working surface of key and keyway, and the contact surface with low relative movement speed, such as support hole, bushing, working surface with wheel axle hole, reducer, etc.
2、 Mechanical parts processing plant — manufacturability of mechanical parts:
When designing mechanical parts, we should not only make them meet the requirements of use, that is, they should have the required working capacity, but also meet the production requirements. Otherwise, they may not be manufactured, or they can be manufactured, but they are costly and uneconomical. Under specific production conditions, if the designed mechanical parts are easy to process and the processing cost is very low, then such parts are said to have good processability. The basic requirements for processability are as follows:
(1) The method of blank preparation in mechanical manufacturing includes: direct use of profile, casting, forging, stamping and welding. The selection of blank is related to the specific production technical conditions, and generally depends on the production batch, material properties and processing possibility.
(2) When designing the structural shape of parts with simple structure, the simplest surface (such as plane, cylindrical surface and spiral surface) and their combination should be adopted. At the same time, the number of machined surfaces and the area of machining should be minimized.
(3) With the increase of precision, the machining cost of parts increases with the increase of precision, especially in the case of high precision. Therefore, high precision should not be pursued without sufficient basis. In the same way, the surface roughness of parts should also be regulated according to the actual needs of the mating surface.