Verification and repair method for root-digging and grinding-remaining hobbing cutter

Abstract

The invention discloses a verification and repair method of a root digging and grinding hobbing cutter, which comprises the following steps of: carrying out trial tooth cutting on a gear blank by using the grinding hobbing cutter, so that a common normal value of the trial tooth cutting blank is equal to a grinding common normal value of a gear to be processed; after trial cutting is completed, the common normal of the trial cutting gear blank is directly ground and machined to the design common normal value of the gear; and detecting three indexes of the effective involute length, the full tooth height and the tooth profile precision of the gear blank, and when the three indexes are completely qualified, judging that the grinding hobbing cutter is suitable for hobbing of a gear. The method is easy to operate and obvious in effect, carburizing and quenching procedures can be omitted, time is saved, cost is reduced, and it can be guaranteed that the tooth root is not ground on the premise that the effective involute length is guaranteed during tooth grinding of a product.

Description

Technical Field

[0001] The invention relates to a verification and repair method for a gear hobbing cutter with root removal and grinding. Background Art

[0002] The stress distribution at the root of carburized and quenched high-precision hardened gears has a great influence on the life and tensile strength of the gears. The root surface of the gear after carburizing and quenching is under compressive stress and can bear large loads without causing crack formation. However, when the root surface of the gear is ground, it is under tensile stress itself. After loading, it is easy to exceed the tensile limit to form micro cracks, and eventually cause broken teeth. Therefore, the carburized hardened gears are rooted in advance, and the effective involute tooth surface is just connected to the root during grinding, and the root is not ground. The root-digging and grinding hobbing cutter generally corresponds to the processing of gears with the same parameters. When the number of gear teeth or the effective involute length changes, the inflection point between the root circle 1 and the involute 2, that is, the product inflection point 3 will change, such as Figure 1 As shown, it is very easy to cause the gear to be scrapped. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a verification and repair method for a gear hobbing cutter with root removal and grinding, which is simple to operate and low in cost.

[0004] The technical solution of the present invention to solve the above technical problems is: a verification and repair method for a root-cutting and grinding gear hobbing cutter, comprising the following steps: Step 1: Use a grinding gear hobbing cutter to test-cut the gear blank, so that the normal value of the test-cut gear blank is equal to the normal value of the grinding gear to be processed; Step 2: After the test cutting, the normal line of the test cut gear blank is directly ground to the designed normal line value of the gear; Step 3: Test the effective involute length of the gear blank, the full tooth height, and the tooth profile accuracy. When the three indicators are fully qualified, it is determined that the grinding hobbing cutter is suitable for gear hobbing.

[0005] In the above verification and repair method of the gear hobbing cutter with root removal and grinding, in the step 3, if the three indicators are unqualified, the gear hobbing cutter with root removal and grinding is repaired according to the following three situations: The first case: the effective involute length is out of tolerance; The second situation: the full tooth height is out of tolerance; The third situation: the effective involute length and the full tooth height are out of tolerance at the same time.

[0006] In the verification and repair method of the above-mentioned root-cutting and grinding gear hobbing cutter, in the step three, for the first case, if the effective involute length exceeds the tolerance, the position of the tool inflection point is changed; The effective involute length tolerance means that the actual involute length is smaller than the theoretical involute length. At this time, the turning point where the root-digging convex position of the gear hobbing cutter is connected with the tool involute is ground, that is, the tool turning point; when the tool turning point is transferred to the tooth top, the turning point of the product involute and the root circle, that is, the product turning point is transferred to the tooth root position. After the transfer, the actual involute length of the product is lengthened; when the actual involute length ≥ the theoretical involute length, the gear hobbing cutter is processed according to the product gear parameters to meet the tooth shape requirements, and the gear hobbing cutter is qualified for grinding.

[0007] In the above-mentioned verification and repair method of the root-removing and grinding gear hobbing cutter, in the step three, for the second situation, if the full tooth height exceeds the tolerance, the gear hobbing cutter tooth shape needs to be ground; the problem causing the full tooth height to exceed the tolerance is that when the chordal tooth thickness of the grinding gear hobbing cutter meets the design size, the actual chordal tooth height is greater than the theoretical chordal tooth height. At this time, according to: the measured full tooth height of the product - the theoretical full tooth height = δ, δ is the excess value, and the gear hobbing cutter tooth top can be ground, and the grinding amount is δ.

[0008] In the above-mentioned verification and repair method of the root-removing and grinding gear hobbing cutter, in the step three, for the third situation, if the effective involute length and the full tooth height are out of tolerance at the same time, it is necessary to simultaneously grind the gear hobbing cutter tooth shape and change the tool turning point; the tool turning point moves toward the tooth top of the grinding gear hobbing cutter, and at the same time, the tooth top width of the grinding gear hobbing cutter is narrowed and the tooth top of the grinding gear hobbing cutter is shortened for shaping, so as to increase the effective involute length and shorten the full tooth height.

[0009] In the above-mentioned verification and repair method of the root-removing and grinding gear hobbing cutter, in step three, the deformation of the gear after carburizing and quenching in actual production is taken into consideration, and the inflection point of the product moves downward by 0.1 to 0.3 mm toward the tooth root.

[0010] The beneficial effects of the present invention are as follows: the present invention is simple to operate and has obvious effects, and can omit the carburizing and quenching process, save time, and reduce costs. It is a correction of the grinding gear hobbing cutter by reverse deduction from the geometric tooth shape of the product, and can ensure that the tooth root is not ground while ensuring the effective involute length during gear grinding. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the product inflection point.

[0012] Figure 2 It is a flow chart of the present invention.

[0013] Figure 3 Schematic diagram of the wear amount.

[0014] Figure 4 A schematic diagram of the three indicators.

[0015] Figure 5 This is a repair diagram for the first case.

[0016] Figure 6This is a repair diagram for the second case.

[0017] Figure 7 This is a repair diagram for the third case.

[0018] In the figure, 1 is the root circle, 2 is the product involute, 3 is the product inflection point, 4 is the root convex position, 5 is the tool involute, 6 is the tool inflection point, A is the grinding amount, B is the tooth profile accuracy, C is the effective involute length, D is the full tooth height, E is the full tooth height after grinding, F is the full tooth height before grinding, G is the tool involute length before grinding, H is the tool involute length after grinding, I is the tooth top gap length before grinding, and J is the tooth top gap length after grinding. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] like Figure 2 As shown, a verification and repair method for a root-cutting and grinding gear hobbing cutter comprises the following steps: Step 1: Use a grinding gear hobbing cutter to test-cut the gear blank so that the normal value of the test-cut gear blank is equal to the normal value of the gear to be processed. Figure 3 shown.

[0021] Step 2: After the trial cutting, the normal line of the trial cut gear blank is directly ground to the designed normal line value of the gear.

[0022] Step 3: Test the effective involute length C, full tooth height D, and tooth profile accuracy B of the gear blank. Figure 4 As shown; when the three indicators are completely qualified, it is determined that the grinding hobbing cutter is suitable for gear hobbing. If the three indicators are unqualified, the grinding hobbing cutter is repaired according to the following three situations: The first case: the effective involute length is out of tolerance; The second situation: the full tooth height is out of tolerance; The third situation: the effective involute length and the full tooth height are out of tolerance at the same time.

[0023] like Figure 5 As shown, for the first case, if the effective involute length exceeds the tolerance, the position of the tool turning point is changed; The effective involute length tolerance means that the actual involute length is less than the theoretical involute length. At this time, the turning point where the root digging convex position 4 of the gear hobbing cutter and the tool involute 5 are connected is the tool inflection point 6; when the tool inflection point 6 is transferred to the tooth top, the inflection point of the product involute 2 and the root circle 1, that is, the product inflection point 3 is transferred to the tooth root position. After the transfer, the actual involute length of the product is lengthened; when the actual involute length ≥ the theoretical involute length, the gear hobbing cutter is processed according to the product gear parameters to meet the tooth shape requirements, and the gear hobbing cutter is qualified for regrinding.

[0024] like Figure 6 As shown, for the second case, if the full tooth height exceeds the tolerance, the gear hobbing cutter tooth shape needs to be ground; the problem causing the full tooth height to exceed the tolerance is that when the chordal tooth thickness of the gear hobbing cutter meets the design size, the actual chordal tooth height is greater than the theoretical chordal tooth height. At this time, according to: the measured full tooth height of the product - the theoretical full tooth height = δ, δ is the excess value, and the gear hobbing cutter tooth top can be ground, and the grinding amount is δ.

[0025] like Figure 7 As shown, for the third case, if the effective involute length and the full tooth height are out of tolerance at the same time, it is necessary to simultaneously grind the tooth shape of the grinding gear hobbing cutter and change the tool turning point 6; the tool turning point 6 moves toward the tooth top of the grinding gear hobbing cutter, and at the same time, the tooth top width of the grinding gear hobbing cutter is narrowed and the tooth top of the grinding gear hobbing cutter is shortened for shaping, so as to increase the effective involute length and shorten the full tooth height.

[0026] The tooth profile change of the grinding gear hobbing cutter mainly affects the gear product tooth profile in the above three aspects, and the product tooth profile is also indirectly changed mainly by grinding the grinding gear hobbing cutter tooth profile, and then verified by hobbing → grinding of the test piece. The present invention is simple to operate and has obvious effects. It can save the carburizing and quenching process, save time and reduce costs. It is a correction of the grinding gear hobbing cutter by reverse deduction from the product geometric tooth profile. It should be noted that the correction should fully consider the deformation of the gear after carburizing and quenching in actual production, and the product inflection point should be moved down 0.1~0.3mm toward the tooth root.

Claims

1. A verification and repair method for a gear hobbing cutter with root removal and grinding, characterized in that: The following steps are involved: Step 1: Use a grinding gear hobbing cutter to test-cut the gear blank, so that the normal value of the test-cut gear blank is equal to the normal value of the grinding gear to be processed; Step 2: After the test cutting, the normal line of the test cut gear blank is directly ground to the designed normal line value of the gear; Step 3: Test the effective involute length of the gear blank, the full tooth height, and the tooth profile accuracy. When the three indicators are fully qualified, it is determined that the grinding hobbing cutter is suitable for gear hobbing.

2. The verification and repair method of the root-cutting and grinding gear hobbing cutter according to claim 1 is characterized in that: In step 3, if the three indicators are unqualified, the grinding hobbing cutter is repaired according to the following three situations: The first case: the effective involute length is out of tolerance; The second situation: the full tooth height is out of tolerance; The third situation: the effective involute length and the full tooth height are out of tolerance at the same time.

3. The verification and repair method of the root-cutting and grinding gear hobbing cutter according to claim 2 is characterized in that: In the step 3, for the first case, if the effective involute length exceeds the tolerance, the position of the tool turning point is changed; The effective involute length tolerance means that the actual involute length is smaller than the theoretical involute length. At this time, the turning point where the root-digging convex position of the gear hobbing cutter is connected with the tool involute is ground, that is, the tool turning point; when the tool turning point is transferred to the tooth top, the turning point of the product involute and the root circle, that is, the product turning point is transferred to the tooth root position. After the transfer, the actual involute length of the product is lengthened; when the actual involute length ≥ the theoretical involute length, the gear hobbing cutter is processed according to the product gear parameters to meet the tooth shape requirements, and the gear hobbing cutter is qualified for grinding.

4. The verification and repair method of the root-cutting and grinding gear hobbing cutter according to claim 2 is characterized in that: In the step three, for the second situation, if the full tooth height exceeds the tolerance, the tooth shape of the grinding gear hobbing cutter needs to be ground; the problem causing the full tooth height to exceed the tolerance is that when the chordal tooth thickness of the grinding gear hobbing cutter meets the design size, the actual chordal tooth height is greater than the theoretical chordal tooth height. At this time, according to: the measured full tooth height of the product - the theoretical full tooth height = δ, δ is the excess value, and the tooth top of the grinding gear hobbing cutter can be ground, and the amount of grinding is δ.

5. The verification and repair method of the root-cutting and grinding gear hobbing cutter according to claim 2 is characterized in that: In the step three, for the third situation, if the effective involute length and the full tooth height are out of tolerance at the same time, it is necessary to simultaneously grind the tooth shape of the grinding gear hobbing cutter and change the tool turning point; the tool turning point moves toward the tooth top of the grinding gear hobbing cutter, and at the same time, the tooth top width of the grinding gear hobbing cutter is narrowed and the tooth top of the grinding gear hobbing cutter is shortened for shaping, so as to increase the effective involute length and shorten the full tooth height.

6. The verification and repair method of the root-cutting and grinding gear hobbing cutter according to claim 2, characterized in that: In the step 3, considering the deformation of the gear after carburizing and quenching in actual production, the inflection point of the product moves downward by 0.1-0.3 mm toward the tooth root.

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