High precision machining of gear shaft journal with large length diameter ratio

In order to reduce the dimensional error caused by the cutting tool, carry out multiple trial cuts before finishing, master the error between the theoretical value and the actual value of the cutting depth, and measure the size of the machined part for many times in the intermediate process, so as to adjust the feed at any time. The turning parameter test of slender shaft is carried out, and the appropriate cutting parameters are selected from the aspects of blade consumption and machining effect. See table for partial data of test process intercepted.

Cutting speed, m / minFeed rate, mm / minCutting capacity, mmBlade material

According to the test results, it is concluded that the machining effect is the best when the cutting speed is 100M / min, the feed rate is 0.2mm/min, and the cutting rate is 0.06mm. In order to control the geometric tolerance of the journal, an appropriate way is adopted to reduce the alignment error of machining. The clamping method of one clamp and one support is adopted, and several runout inspection requirements are added before the low-pressure pinion sample turns over. When aligning the low-pressure pinion sample after turning over, recheck and adjust the runout at the increased position before turning over until it is the same as that before turning over. Finish machining is based on the same position to make up for the error caused by secondary clamping.

Spindle speed r / minGrinding wheel speed m / minFeed speed mm / minGrinding depth mm / time

Finish machining of shaft diameter adopts the method of one clip and one top, with bulkhead machining at both ends and auxiliary support in the middle. In order to ensure the machining accuracy requirements, the following three sets of schemes are formulated:

Scheme 1: high precision CNC deep hole lathe (pt1-1250 Ⅱ 6000) is used for finishing machining. The equipment is equipped with high-precision power grinding head, which can grind the tooth top circle and shaft diameter. The two sequences of finishing machining and finishing grinding are completed by the same equipment, which can avoid the error caused by the secondary clamping and alignment of the workpiece and improve the machining accuracy.

Scheme 2: the NC rotor lathe is used for processing. The NC rotor lathe is equipped with a special abrasive belt polishing machine. After finishing with a margin of 0.02mm, the shaft diameter and tooth top are polished.

Scheme 3: the NC rotor lathe is used to finish turning the outer circle and shaft diameter of the gear, the grinding amount of the outer circle is reserved, and the outer circle and shaft diameter of the gear are grinded by the rotary length horizontal grinder or kvh4-2600 horizontal grinding center. See Table 2 for grinding test data.

Under the conditions of spindle speed of 20R / min, grinding wheel speed of 450m / min, feed speed of 80mm / min and grinding depth of 0.002mm/time, the machining effect is the best.

After experimental demonstration, the three schemes can achieve the expected machining accuracy. As the abrasive belt grinding is adopted in scheme 2, due to the limitation of the cutter table equipped with the machine tool, it requires a large working space, and the processing efficiency is slightly lower than that of kvh4-2600 horizontal grinding center. Therefore, scheme 1 and scheme 3 are the preferred schemes.

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