The quality inspection of transmission shaft forgings generally includes three aspects: firstly, dimensional accuracy; The second is surface roughness; The third is the accuracy of shape and position.
- (1) The measurement of dimensional accuracy for shaft parts requires high dimensional accuracy and is simple for transmission shafts, except for threads, which can be completed using general measurement methods. The main measuring tools are vernier calipers, spiral micrometers, and thread micrometers or thread plug gauges.
- (2) When the surface roughness requirement of a part is high, a surface roughness measuring instrument is used for measurement. However, when the surface roughness requirement of forging is not high, such as below Ka0.4, a surface roughness comparison sample is used for comparison.
- (3) The measurement of shape and position accuracy the measurement of shape and position accuracy is the most important and difficult in mechanical processing, and some cannot be measured by instruments and require auxiliary tools. To know how to measure shape and position accuracy, it is necessary first to understand the indicators of shape accuracy and position accuracy. The shape accuracy of mechanical parts mainly refers to the requirements of a single element, independent of other points, lines, and surfaces, such as straightness, roundness, flatness, and cylindricity. The positional accuracy of mechanical components mainly refers to the relationship between two or more elements, such as parallelism, verticality, inclination, positional accuracy, coaxiality, symmetry, circular runout, and total runout. Two other requirements can refer to both single and multiple elements, such as line profile and surface profile.
The main requirement for the accuracy of the shape and position of the transmission shaft is the circular runout of each surface. When measuring, one method is to install the center holes at both ends of the forgings on the center of the deflection gauge and contact the measuring head of the dial gauge (using a dial gauge for high accuracy) with the measuring surface of the workpiece. (Pay attention to two points: one is that the measuring head should be perpendicular to the measuring surface of the workpiece, and the other is that the pre-compression amount of the measuring head should not be too much, usually around 0.2). In the absence of a deflection instrument, the second method can be used, which is to use the two centers used for machining on the lathe for measurement, and the measurement method is similar to the first method. The third method is to use a “V” block for measurement, which means that the straight range of shaft parts is placed as a reference in the V-shaped groove. The measuring head of a dial gauge (using a dial gauge for high accuracy) is used to measure contact with the forging surface (using the same method as before). The workpiece is rotated to measure the relationship between the measured surface and the reference surface and then converted into the shape and position accuracy requirements on the drawing.