CNC Knowledge: Principles for determining tooth grinding compensation

In the gear grinding process, volume control is a crucial link. The remaining quantity, that is, the quantity that needs to be removed during the grinding process, directly affects the machining accuracy and performance of the gear. In order to effectively control the retention volume, a series of technical measures and operational specifications must be adopted.

Here are some key points regarding reserve control:

1. The size of the margin: The grinding margin should be as small as possible, but it should also be sufficient to ensure that all unqualified surface layers can be removed, including the deformed layer caused by heat treatment and errors left by the previous one. process. This can not only improve production efficiency, but also guarantee the load capacity of the gear.

Generally speaking, the gear grinding allowance should not exceed 0.2mm on one side to ensure the accuracy of the gear after grinding.

2. Tolerance uniformity: In order to ensure the uniformity of the gear grinding process and the consistency of the final product, the gear grinding tolerance should be as uniform as possible in the circumferential direction, in the direction of the shape of the gears. teeth and in the direction of the width of the teeth. avoid residual black skin. This requires strict error control in the gear pre-cutting process. For example: Since gear pre-cutting and gear grinding do not use the same processing standard, the gear tooth profile runout should be limited during gear pre-cutting to avoid inconsistencies. Margins when grinding gears.

3. Allocation form: There are generally two common forms of gear grinding allocation. The first is to leave a grinding allowance on both the tooth surface and the gear foot. This will help improve the bending resistance of the gear root and eliminate thermal stress concentration at the gear root. The other is that the gear tooth surface has a uniform grinding allowance, and no grinding allowance is left at the gear foot. For example, there is a certain amount of digging at the root of the tooth when cutting.

The shape to choose should be determined according to the specifications, structural shape and material of the gear, the precision of the tooth blank (including the reference precision and the precision of the teeth of the front gear grinding), heat treatment and gear deformation. grinding equipment.

4. Deformation after heat treatment: Since the gear will deform after heat treatment, the accuracy will decrease by 1-2 levels. Therefore, the size of the gear grinding allowance should be determined by the maximum deformation of the gear after heat treatment. During the heat treatment process, the margin protection method can be used to protect the gear to reduce deformation and ensure machining accuracy.

5. Accuracy and roughness: The precision of gear grinding can generally reach level 6 or above, and the roughness can exceed Ra0.8. This requires that when determining the gear grinding allowance, it should be fully considered whether the gear grinding process can meet these technical requirements.

6. Equipment control precision: the precision of centering and tolerance distribution of the gear grinding machine, the precision of the timing control of the tool and workpiece, the repetition precision of the machine- tool, geometric accuracy, etc., largely determine the accuracy of gear processing. Therefore, equipment accuracy and maintenance are also factors that cannot be ignored in retention control.

7. Production efficiency: In order to ensure the precision of gear grinding and the quality of tooth surface, productivity should be improved as much as possible, which involves reasonable selection of gear grinding parameters and optimization of the process flow.

In general, gear grinding allowance control is a process that requires careful consideration of several factors, including the technical requirements of the gear, the quality of previous processes, the impact of heat treatment deformation and improving production efficiency. By precisely controlling the gear grinding allowance, the accuracy and performance of the gear can be guaranteed to meet design and usage standards.