Spline connection is a connection form that can transmit large torque and high centering accuracy. It is widely used in mechanical transmission. In the gearbox of machine tools, automobiles, tractors and so on, the sliding of spline gear sleeve and spline shaft is mostly used as variable speed transmission. Therefore, we must pay attention to its accuracy and quality when manufacturing external splines. Now let's introduce the quality inspection and analysis of external spline.
1、 Inspection of external spline
In single piece and small batch production, the deviation of various elements of external spline is generally detected with general measuring tools (vernier caliper, micrometer, dial indicator, etc.). The measurement items are as follows:
(1) Measure the key width and small diameter of the external spline with a micrometer or vernier caliper.
(2) Use a dial indicator to measure the parallelism and symmetry of the side of the external spline key to the axis of the workpiece. The measurement method of symmetry is compared with the measurement method of trial cutting and knife alignment.
In batch and mass production, the inspection method of combining comprehensive gauge and single stop gauge is adopted. The comprehensive gauge of external spline shall be used to check the comprehensive influence of small diameter, large diameter, key width and large diameter on the coaxiality of small diameter, the symmetry and bisection of spline, etc., so as to ensure the matching requirements and installation requirements of spline. The comprehensive ring gauge has only the through end, so it is also necessary to check the minimum limit dimensions of small diameter, large diameter and key width with a single end stop gauge (chuck) to ensure that its actual dimension is not less than the minimum limit dimension. During the inspection, if the comprehensive gauge passes and the single end clamp fails, the external spline is qualified.
2、 Quality analysis of external spline milling
1. Precautions for external spline milling
When milling external splines with a three face edge milling cutter on the milling machine, the following matters should be paid attention to:
(1) Accurately correct the position of the fixture (dividing head, tailstock), and ensure that the workpiece axis is parallel to the workbench table and consistent with the longitudinal feed direction.
(2) Under the condition that the width of the three side edge milling cutter does not cut to the side of the adjacent key, a large size should be selected to increase the rigidity of the milling cutter. The cutting edge of the milling cutter should be sharp, and the runout of the side cutting edge should be small after installation.
(3) Carefully adjust the cutting position of the milling cutter. When milling with a single cutter, the tool setting must be accurate.
(4) Carefully operate the indexing operation to prevent the error of indexing or the inaccuracy of bisection caused by the failure to eliminate the indexing gap.
(5) Select the milling amount reasonably to avoid the ripple on the side of the key caused by vibration during machining. For the slender spline shaft with poor rigidity, measures should be taken to improve the rigidity in workpiece processing.
2. Quality analysis of external spline milling
Common quality problems, causes and corresponding measures in external spline milling:
(1) Key width size out of tolerance: the main reason is that the cutting position is not adjusted correctly or the tool end edge runout is too large when milling with a single tool. It can be improved by accurately adjusting the cutting position of the milling cutter, replacing the washer and reinstalling the milling cutter.
(2) Out of tolerance of spline symmetry: caused by inaccurate calculation, adjustment or indexing of cutting position. It can be improved by re setting the tool or dividing it correctly.
(3) The spline is not evenly divided: the main reasons are that the workpiece center is different from the dividing head, the shaft of the dividing head is too large, and the dividing head is shaken incorrectly. The solution can be used to accurately correct the coaxiality of the workpiece axis and the dividing head; The rotation direction of the indexing handle is consistent to eliminate the gap; Correct indexing method.
(4) The spline is not parallel to the reference axis: the reason for this situation is that the spindle axis of the dividing head is not parallel to the longitudinal feed direction, and the tailstock center is different from the axis of the dividing head, which can be improved by re calibrating the fixture.