1、 Inspection of straight rack
1. Inspection of tooth shape and tooth shape angle: concave convex single tooth template or half tooth template or double half tooth template shall be used for the inspection of tooth shape and tooth shape.
2. Inspection of tooth thickness and groove width: tooth thickness and groove width can be directly inspected with concave convex single tooth template, and tooth thickness and tooth top height can also be measured with tooth thickness vernier caliper. This kind of vernier caliper is composed of two mutually perpendicular vernier calipers. Its marking principle and the method of reading size are the same as that of general vernier calipers. When using, first adjust the vertical ruler to a certain height, then make the end face lean against the tooth top, move the vernier of the level ruler, and make the claw gently contact the tooth surface. At this time, the reading on the level ruler is the fixed chord tooth thickness.
3. Inspection of tooth pitch: generally, the double half tooth template and cross tooth template can be used to measure the tooth pitch. Put two standard cylinders with the same diameter in the adjacent two slots, and measure the span size of the two standard cylinders with a micrometer to obtain the size of the rack tooth pitch.
The measurement of cumulative pitch error is to place two standard cylinders in the slots of the number of teeth to be measured, measure the span size of the two standard cylinders, and subtract the diameter of a standard cylinder to obtain the pitch size and error of the number of teeth to be measured.
4. Inspection of the straightness of the reference line and the parallelism between the reference line and the base plane of the rack: the straightness of the reference line of the rack and the parallelism between the reference line and the base plane are generally inspected by using standard cylinders and dial indicators. Place the standard cylinders in the slots one by one, and use the dial indicators to measure the highest point of the standard cylinder in each slot in turn, From the numerical analysis of each point, we can get whether the straightness of the rack reference line and the parallelism between the reference line and the rack base plane meet the requirements.
In addition, there are certain requirements for the surface roughness of the tooth surface, which is generally inspected by visual inspection and standard sample block comparison.
2、 Processing quality analysis
1. Tooth thickness (or groove width) size out of tolerance: there are two main reasons: first, the tool back is inaccurate or caused by tool drop. Second, the tooth shape angle of shaping planer and slotting cutter is inaccurate.
2. The tooth pitch and the cumulative error of the tooth pitch are out of tolerance: the main reason is that the accuracy of tooth separation is low, resulting in inaccurate displacement; The inaccuracy of the tool back feed will also cause errors in adjacent tooth pitches.
3. Inaccurate tooth shape: the reason is that the tooth shape angle of forming planer and slotting cutter is inaccurate or the cutter installation is inaccurate.
4. The tooth surfaces are not parallel to each other: there are two main reasons for the non parallel tooth surfaces: first, the poor rigidity of the workpiece, resulting in elastic deformation after stress. Second, the working accuracy of the machine tool is low.
5. The straightness of the rack reference line and the parallelism with the base plane are out of tolerance: the straightness of the rack reference line is out of tolerance due to uneven slot width, workpiece clamping deformation and low working accuracy of the machine tool. The main reason why the parallelism of the rack reference line and the base plane is out of tolerance is that the workpiece is not clamped correctly, and the moving direction of the tooth pitch is not parallel to the workbench.
6. The straightness of the rack reference line and the parallelism with the base plane are out of tolerance: the straightness of the rack reference line is out of tolerance due to uneven slot width, workpiece clamping deformation and low working accuracy of the machine tool. The main reason why the parallelism of the rack reference line and the base plane is out of tolerance is that the workpiece is not clamped correctly, and the moving direction of the tooth pitch is not parallel to the workbench.