Machining accuracy is the degree of conformity between the actual size, shape and position of the machined part surface and the ideal geometric parameters required by the drawings. Ideal geometric parameters are average size for size, absolute circles, cylinders, planes, cones and straight lines for surface geometry, and absolute parallelism, perpendicularity, coaxiality and symmetry for mutual positions between surfaces. The deviation between actual geometric parameters and ideal geometric parameters of parts is called machining error. Kaicheng Precision is based on machine tool spindle, rotary thimble, screw and screw rod, axis processing, CNC lathe processing, tool handle and tool rod, quality assurance!
1. Different measuring methods are adopted for processing accuracy according to different contents and requirements of processing accuracy. Generally speaking, there are the following types of methods:
1. According to whether the measured parameters are measured directly or not, they can be divided into direct measurement and indirect measurement.
Direct measurement: Direct measurement of the measured parameters to obtain the measured size. For example, measuring with calipers and comparators. Indirect measurement: Measure the geometric parameters related to the measured size, and obtain the measured size through calculation.
Obviously, direct measurement is more intuitive and indirect measurement is more cumbersome. Generally, indirect measurement is necessary when the measured size or direct measurement can not meet the accuracy requirements.
2. Measurements and relative measurements can be classified according to whether the reading value of the measuring instrument directly represents the measured size.
Absolute measurement: Reading values directly indicate the size of the measured size, such as using vernier calipers.
Relative measurement: The reading value only indicates the deviation of the measured size from the standard value. If the diameter of the axis is measured by a comparator, the zero position of the instrument needs to be adjusted by the gauge block first, and then measured. The measured value is the difference between the diameter of the side axis and the size of the gauge block, which is the relative measurement. Generally speaking, the relative measurement accuracy is higher, but the measurement is more troublesome.
3. According to whether the measured surface is in contact with the measuring head of the measuring instrument, it can be divided into contact measurement and non-contact measurement.
Contact measurement: The measuring head is in contact with the contact surface, and the measuring force has a precise effect. If measuring parts with micrometer.
Non-contact measurement: The measuring head does not contact the surface of the part under test. Non-contact measurement can avoid the influence of measuring force on the measurement results. For example, projection method and light wave interferometry are used to measure.
4. According to the number of parameters measured at one time, it can be divided into single measurement and comprehensive measurement.
Single measurement; each parameter of the part under test is measured separately.
Comprehensive measurement: The comprehensive index reflecting the relevant parameters of parts is measured. For example, when measuring threads with a tool microscope, the actual diameter of threads, the half-angle error of tooth profile and the accumulated error of pitch can be measured respectively.