In the process of precision machining, there are many factors that affect the machining accuracy. Different machining methods can achieve different accuracy under different machining conditions
of If we blindly pursue the machining accuracy, it will reduce the production efficiency and increase the cost of precision mechanical parts processing. Therefore, precision machining enterprises are
On the premise of this, we should try our best to improve efficiency and reduce production costs. The machining accuracy of precision mechanical parts can be divided into dimensional accuracy, shape accuracy and position accuracy
Precision. Therefore, the machining accuracy is measured by dimensional tolerance, shape tolerance and position tolerance.
The method to obtain the dimensional accuracy of the part: trial cutting method: that is, first try to cut a small part of the machined surface, measure the size obtained from the trial cutting, and properly according to the processing requirements
Adjust the position of the cutting edge of the tool relative to the workpiece, try to cut again, and then measure. After two or three times of test cutting and measurement, when the precision mechanical parts are machined to the required size
After the calculation, the whole surface to be machined shall be cut, the trial cutting and turning of journal size for precision mechanical parts processing, the online measurement and grinding of journal size, and the box parts
Trial boring processing of hole series and manual fine grinding of precision gauge block. All are processed by trial cutting method.
The accuracy of the trial cutting method may be very high. It does not require complex devices, but this is time-consuming and requires multiple adjustments, trial cutting, measurement, calculation and efficiency
It is low and depends on workers' technical skills and the accuracy of measuring instruments. The quality is unstable, so it is only used for single piece small batch production.
The adjustment method is to adjust the accurate relative position of the machine tool, fixture, cutter and workpiece with samples or standard parts in advance, so as to ensure the precision mechanical parts processing ruler
Inch accuracy, and the size remains unchanged during the processing of a batch of parts. This is the adjustment method. Machining shaft parts on multi tool lathe or hexagonal automatic lathe, and milling
Milling grooves on the machine and grinding excircles and holes on the centerless grinder are all processed by adjustment method.
If the milling machine fixture is used, the tool position is determined by the tool setting block. The essence of the adjustment method is to use the fixed distance device or tool setting device on the machine tool or pre adjust
The tool holder can make the tool reach a certain position accuracy relative to the machine tool or fixture, and then process a batch of workpieces. In mass production, the travel stop and sample are used
Adjust the tool setting devices such as parts and templates. The adjustment method has better stability of processing accuracy than the trial cutting method, higher productivity, and lower requirements for machine tool operation,
However, the requirements for machine tool adjustment workers are high, and they are often used for mass production and mass production.
Sizing method: the method of using the corresponding size of the tool to ensure the size of the part to be processed is called sizing method, which uses standard size tools to add
The size of the machining surface is determined by the tool size. That is to say, a tool with certain dimensional accuracy is used to ensure the accuracy of the parts to be processed. If square broach is used
The square hole, the inner hole processed by drill, reaming drill, reaming or boring block, and the groove surface on both sides of the workpiece milled by the combined milling cutter are all processed by the dimensional tool method.