Carburizing and quenching gear grinding allowance optimization method

Abstract

The invention relates to the technical field of gear machining, in particular to a carburizing and quenching gear grinding allowance optimization method. Comprising the following steps that a gear is preliminarily aligned, and a starting tooth of the gear is determined; according to the starting teeth, obtaining tooth pitch accumulated deviation distribution of the gear; an alignment auxiliary line is obtained according to a connecting line between the gear teeth where the maximum value and the minimum value of the obtained pitch accumulated deviation distribution are located; a secondary alignment direction is obtained according to the alignment auxiliary line, the included angle between the secondary alignment direction and the alignment auxiliary line is equal to 90 degrees minus the pressure angle of the gear, and the secondary alignment direction faces the direction where the starting gear is located; the alignment amount is obtained according to the pitch accumulated deviation distribution, secondary alignment is conducted on the gear according to the alignment amount and the secondary alignment direction, and a secondary alignment result is obtained; and grinding the gear according to the secondary alignment result. Through secondary alignment, the effect of peak shifting and valley filling is achieved, the tooth pitch accumulated deviation and the tooth grinding allowance distribution uniformity are improved, and the maximum tooth grinding allowance is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of gear processing, and in particular to a method for optimizing the grinding allowance of a carburized and quenched gear. Background Art

[0002] When manufacturing gears, carburizing and quenching are usually used to ensure that the gear tooth surface has high hardness and wear resistance. After the carburizing and quenching process, the gear as a whole will be deformed, so it must go through a gear grinding process, that is, the gear tooth surface is ground with a gear grinding machine to correct the gear tooth accuracy, reduce the vibration and noise during transmission, and make the transmission more stable.

[0003] At present, large diameter gears usually produce large heat treatment deformation after carburizing and quenching, which is manifested as a large change in the normal line. The conventional processing technology for gears after quenching is: align according to the radial runout of the gear ring, then fine-turn the end face of the inner hole of the gear, and finally grind the gear. For gears with large normal line changes, after aligning the radial runout of the gear ring according to the conventional method, the total cumulative deviation of the tooth pitch is very large, which affects the subsequent grinding process, making the tooth surface grinding allowance uneven, which will lead to problems such as normal line tolerance, uneven hardness of the tooth surface, and inconsistent depth of the hardened layer, thereby affecting the bending fatigue life and contact fatigue life of the gear. Summary of the invention

[0004] In view of the above-mentioned defects, the technical problem to be solved by the present invention is to provide a method for optimizing the grinding allowance of carburized and quenched gears, which can reduce the cumulative total deviation of the tooth pitch and improve the uniformity of the grinding allowance.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] A method for optimizing the grinding allowance of a carburized and quenched gear comprises the following steps:

[0007] Initially align the gear and determine the starting tooth of the gear;

[0008] Obtaining a gear pitch cumulative deviation distribution according to the starting tooth;

[0009] Obtaining the maximum value and the minimum value of the cumulative pitch deviation distribution, and obtaining an auxiliary alignment line according to a line connecting the gear teeth where the maximum value and the minimum value of the cumulative pitch deviation distribution are located;

[0010] A secondary alignment direction is obtained according to the alignment auxiliary line, wherein the angle between the secondary alignment direction and the alignment auxiliary line is equal to 90° minus the angle of the gear pressure angle, and the secondary alignment direction is in the direction where the starting tooth is located;

[0011] Obtaining an alignment amount according to the cumulative pitch deviation distribution, performing secondary alignment on the gear according to the alignment amount and the secondary alignment direction, and obtaining a secondary alignment result;

[0012] The gears are ground according to the secondary alignment result.

[0013] By adopting the above scheme, after the gear is aligned according to the radial runout, it is then aligned again along the secondary alignment direction, and the alignment amount is determined according to the distribution of the cumulative pitch deviation, and the alignment is performed according to the alignment amount and the secondary alignment direction, thereby adjusting the distribution of the cumulative pitch deviation and the grinding allowance of the gear. Since the secondary alignment direction is located on the radial line of the gear, the angle between the secondary alignment direction and the alignment auxiliary line is 90° minus the angle of the gear pressure angle, and the secondary alignment direction is toward the direction of the starting tooth, which makes the large part of the gear's cumulative pitch deviation move toward the part with a small cumulative pitch deviation. After the secondary alignment, the distribution of the cumulative pitch deviation of all gear teeth becomes more uniform, and the total cumulative pitch deviation becomes smaller. In addition, the distribution of the grinding allowance of all gear teeth is more uniform, and the maximum grinding allowance of the gear is reduced.

[0014] Preferably, the preliminary alignment of the gears comprises:

[0015] Obtain the radial runout test results of the gear;

[0016] The gears are preliminarily aligned according to the radial runout detection results.

[0017] Preferably, after the gear is initially aligned according to the radial runout detection result, the end face and the inner hole reference band are initially machined, and part of the grinding allowance is reserved at the end face and the inner hole reference band of the gear. When the reference band of the gear is initially machined, part of the grinding allowance is reserved at the reference band of the gear, which facilitates the subsequent re-machining of the reference band after the secondary alignment of the gear.

[0018] Preferably, the calculation formula for obtaining the alignment amount according to the cumulative pitch deviation distribution is: In the formula: e is the positive quantity, F p is the cumulative total deviation of the tooth pitch, and α is the gear pressure angle. The alignment amount determined by this calculation formula can directly calculate the appropriate alignment amount without making multiple attempts to obtain the appropriate alignment amount.

[0019] Preferably, the F p It is the average value of the total cumulative deviation of the tooth pitch of the left and right tooth surfaces of the gear. It improves the calculation accuracy of the alignment amount of the secondary alignment.

[0020] Preferably, the gear pressure angle is 20°.

[0021] Preferably, after obtaining the secondary alignment result, the method further comprises: re-turning the gear end face and inner hole reference band. Re-turning the reference band facilitates the subsequent gear grinding operation.

[0022] Preferably, after obtaining the gear pitch cumulative deviation distribution according to the starting tooth, the method further includes: screening out gears whose normal line variation is greater than or equal to 50% of the maximum value of the grinding allowance. For gears whose normal line variation is less than 50% of the grinding allowance, only preliminary alignment can be performed before subsequent grinding process. Only screening out gears whose normal line variation is greater than or equal to 50% of the maximum value of the grinding allowance for subsequent secondary alignment can reduce costs.

[0023] Preferably, the step of determining the starting tooth of the gear comprises:

[0024] Get the number of teeth of the gear, take one of the gear teeth as the starting tooth; mark the position of the starting tooth on the gear. By marking the position of the starting tooth on the gear, it is convenient to correspond the theoretical secondary alignment direction with the actual secondary alignment direction of the gear.

[0025] In summary, the method for optimizing the grinding allowance of carburized and quenched gears provided by the present invention has at least the following beneficial effects: through secondary alignment, the effect of shifting peaks and filling valleys is achieved, the uniformity of the cumulative pitch deviation and the grinding allowance distribution is improved, and the maximum grinding allowance of the gear is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without expending any novel work.

[0027] Figure 1 1 is a schematic diagram of the alignment direction when the peak of the cumulative pitch deviation is located at the 115th tooth and the trough is located at the 40th tooth in an embodiment of the present invention;

[0028] Figure 2 It is a schematic diagram of the cumulative pitch deviation and radial runout distribution of all teeth of the gear after the gear is aligned according to radial runout in an embodiment of the present invention;

[0029] Figure 3 is a schematic diagram of the distribution of the grinding allowance of all teeth of the gear after the gear is aligned according to radial runout in an embodiment of the present invention;

[0030] Figure 4 Schematic diagram of cumulative pitch deviation and radial runout distribution of all gear teeth after secondary alignment in an embodiment of the present invention;

[0031] Figure 5 Schematic diagram of the distribution of the grinding allowance of all gear teeth after secondary alignment in an embodiment of the present invention.

[0032] The reference numerals include: gear 1 , starting tooth 2 , starting tooth mark 3 , and alignment auxiliary line 4 . DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention, Figure 1-5 The present invention is further described in detail with specific implementation modes.

[0034] See also Figure 1-5 The present embodiment provides a method for optimizing the grinding allowance of a carburized and quenched gear 1, comprising the following steps:

[0035] Initially align gear 1 and determine the starting tooth 2 of gear 1;

[0036] The tooth pitch cumulative deviation distribution of the gear 1 is obtained according to the starting tooth 2; wherein the tooth pitch cumulative deviation distribution is detected by a detection device.

[0037] Obtain the maximum and minimum values ​​of the cumulative pitch deviation distribution, and obtain the alignment auxiliary line 4 according to the connecting line between the gear teeth where the maximum and minimum values ​​of the cumulative pitch deviation distribution are located;

[0038] A secondary alignment direction is obtained according to the alignment auxiliary line 4, wherein the angle between the secondary alignment direction and the alignment auxiliary line 4 is equal to 90° minus the pressure angle of the gear 1, and the secondary alignment direction is in the direction where the starting tooth 2 is located;

[0039] The alignment amount is obtained according to the distribution of the cumulative deviation of the tooth pitch, and the gear 1 is aligned for the second time according to the alignment amount and the second alignment direction to obtain the second alignment result;

[0040] Gear 1 is ground according to the secondary alignment result.

[0041] By adopting the above scheme, after the gear 1 is aligned according to the radial runout, it is then aligned again along the secondary alignment direction, and the alignment amount is determined according to the distribution of the cumulative pitch deviation, and the alignment is performed according to the alignment amount and the secondary alignment direction, so as to adjust the distribution of the cumulative pitch deviation and the grinding allowance of the gear 1. Since the secondary alignment direction is located on the radial line of the gear 1, the angle between the secondary alignment direction and the alignment auxiliary line 4 is 90° minus the angle of the gear pressure angle, and the secondary alignment direction is in the direction of the starting tooth 2, which makes the large part of the cumulative pitch deviation of the gear 1 move toward the part with small cumulative pitch deviation, achieving the effect of shifting peaks and filling valleys. After the secondary alignment, the distribution of the cumulative pitch deviation of all teeth of the gear 1 becomes more uniform, and the total cumulative pitch deviation becomes smaller. In addition, the distribution of the grinding allowance of all teeth of the gear 1 is more uniform, and the maximum grinding allowance of the gear 1 is reduced.

[0042] Preferably, the preliminary alignment of the gear 1 comprises the following steps: obtaining a radial runout detection result of the gear 1; and preliminary alignment of the gear 1 according to the radial runout detection result.

[0043] The step of obtaining the radial runout test result of the gear 1 includes: installing the gear 1 on a rotary workbench; detecting the radial runout of all teeth of the gear 1 by a detection device, and the detection device preferably adopts a gear grinding machine, and the radial runout of the gear 1 can be detected by the gear grinding machine. In addition, the detection device can also select a gear tester in the prior art. The gear grinding machine is a commonly used gear grinding device and gear detection device in the prior art. The gear grinding machine can detect the radial runout, grinding allowance and cumulative pitch deviation of the gear 1, and is easy to operate.

[0044] Preferably, after the gear 1 is preliminarily aligned according to the radial runout detection result, the end face and the inner hole reference zone are initially machined, and part of the grinding allowance is reserved at the end face and the inner hole reference zone of the gear 1.

[0045] As a preferred method, the calculation formula for the alignment amount is obtained according to the cumulative deviation distribution of the pitch: In the formula: e is the positive quantity, F p is the cumulative total deviation of the tooth pitch, and α is the gear pressure angle. Specifically, F p It refers to the maximum cumulative pitch deviation within any arc segment (k = 1 to k = z, z is the number of teeth on the gear) on the same side of the gear, which is expressed as the total amplitude of the cumulative pitch deviation curve. p is the average value of the cumulative total deviation of the tooth pitch of the left tooth surface and the right tooth surface of gear 1. The gear pressure angle is 20°. In some embodiments, the gear pressure angle may also be 25°.

[0046] Preferably, after obtaining the secondary alignment result, it also includes: a heavy-turn gear 1 end face and inner hole reference zone.

[0047] Preferably, after obtaining the gear pitch cumulative deviation distribution according to the starting teeth, the method further includes: screening out the gears 1 whose normal line variation is greater than or equal to 50% of the maximum value of the grinding allowance. For the gears 1 whose normal line variation is less than 50% of the grinding allowance, only preliminary alignment can be performed before the subsequent grinding process. Only screening out the gears 1 whose normal line variation is greater than or equal to 50% of the maximum value of the grinding allowance for subsequent secondary alignment can reduce costs.

[0048] Preferably, the step of determining the starting tooth 2 of the gear 1 includes: obtaining the number of teeth of the gear 1, taking one of the teeth of the gear 1 as the starting tooth 2; and marking the position of the starting tooth 2 on the gear 1. Specifically, a marker can be used to mark the starting tooth 2 on the gear 1, and the position of the starting tooth 2 on the gear 1 can be confirmed by the starting tooth mark.

[0049] In order to ensure that the cumulative pitch deviation and grinding allowance distribution of gear 1 meet the requirements, after the secondary alignment of gear 1 and before the gear 1 is ground, the cumulative pitch deviation and full tooth scanning grinding allowance of gear 1 are detected by a gear grinding machine, and whether they meet the requirements is determined based on the test results. For gear 1 that meets the requirements, the subsequent grinding process is carried out.

[0050] This embodiment provides a set of comparative data of examples before and after the gear 1 grinding allowance is optimized by the above method. A gear 1 has a total number of 142 teeth, and the gear pressure angle α is 20°. The gear grinding machine detects that the normal line variation is 0.7mm. Execute step S1 to preliminarily align the gear 1 according to the radial runout. After the gear 1 is preliminarily aligned, the gear 1 is tested by the gear grinding machine to obtain the cumulative pitch deviation and radial runout distribution curve of the gear 1 (details are shown in Figure 1). Figure 2 , Figure 2 Fp is the cumulative total deviation of the tooth pitch, fp is the limit deviation of the tooth pitch, fu is the deviation of the adjacent tooth pitch, and Fr is the radial runout). The grinding allowance distribution curve of the full teeth of gear 1 is tested by a gear grinding machine (details are Figure 3 ). Among them, the cumulative total deviation of the right tooth surface is approximately equal to 0.93mm, the cumulative total deviation of the left tooth surface is 0.96mm, the average value of the cumulative total deviation of the left and right tooth surfaces is approximately equal to 0.95mm, the radial runout is approximately equal to 0.25mm, and the peak of the cumulative deviation curve of the left and right tooth surfaces is located at the 115th tooth, and the trough is located at the 40th tooth.

[0051] According to the alignment amount of secondary alignment, according to the alignment amount calculation formula In order to make the calculation more accurate, when calculating the alignment amount, substitute the average value of the cumulative total deviation of the left tooth surface and the right tooth surface into the calculation formula F pCalculation shows that the alignment amount e is 0.45 mm. The angle between the secondary alignment direction and the line connecting the 115th tooth and the 40th tooth is equal to 90° minus the pressure angle, and the secondary alignment direction is in the direction of the starting tooth 2. For details on the alignment direction of the secondary alignment, refer to Figure 1 After the second alignment, the gear 1's pitch cumulative deviation and radial runout distribution curve are tested by the gear grinding machine (details Figure 4 ), the distribution curve of the grinding allowance of the whole gear 1 is detected by the gear grinding machine (details Figure 5 ). Among them, the cumulative total deviation of the right tooth pitch is about 0.40mm, the cumulative total deviation of the left tooth pitch is about 0.57mm, the average cumulative total deviation of the left and right tooth pitches is 0.49mm, and the radial runout is about 0.94mm. It can be seen that after the second adjustment, the cumulative total deviation of the tooth pitch is reduced, and combined with Figure 2 and Figure 4 It can be seen that the distribution of the cumulative pitch deviation is more uniform. Specifically, the cumulative total deviation of the right tooth surface is reduced by 0.53mm, the cumulative total deviation of the left tooth surface is reduced by 0.39mm, and the average cumulative total deviation of the left and right tooth surfaces is reduced by 0.46mm; the maximum grinding allowance of the left tooth surface is reduced by 0.03mm, and the minimum grinding allowance is reduced by 0.31mm. The maximum grinding allowance of the right tooth surface is reduced by 0.34mm, and the minimum grinding allowance is reduced by 0.31mm, which can meet the grinding allowance requirements.

[0052] It should be noted that the words indicating direction in this article, such as up and down, are all based on Figure 1 The setting of the direction is only for the convenience of description and has no other specific meaning.

[0053] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or device. In the absence of further restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the article or device including the above elements.

[0054] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for optimizing the grinding allowance of carburized and quenched gears, characterized in that: The following steps are involved: Initially align the gear and determine the starting tooth of the gear; Obtaining a gear pitch cumulative deviation distribution according to the starting tooth; Obtaining the maximum value and the minimum value of the cumulative pitch deviation distribution, and obtaining an auxiliary alignment line according to a line connecting the gear teeth where the maximum value and the minimum value of the cumulative pitch deviation distribution are located; A secondary alignment direction is obtained according to the alignment auxiliary line, wherein the angle between the secondary alignment direction and the alignment auxiliary line is equal to 90° minus the angle of the gear pressure angle, and the secondary alignment direction is in the direction where the starting tooth is located; Obtaining an alignment amount according to the cumulative pitch deviation distribution, performing secondary alignment on the gear according to the alignment amount and the secondary alignment direction, and obtaining a secondary alignment result; The gears are ground according to the secondary alignment result.

2. The method for optimizing the grinding allowance of carburized and quenched gears according to claim 1, characterized in that: The preliminary alignment of the gears includes: Obtain the radial runout test results of the gear; The gears are preliminarily aligned according to the radial runout detection results.

3. The method for optimizing the grinding allowance of carburized and quenched gears according to claim 2, characterized in that: After the gear is preliminarily aligned according to the radial runout detection result, the end face and the inner hole reference zone are initially machined, and part of the grinding allowance is reserved at the end face and the inner hole reference zone of the gear.

4. A method for optimizing the grinding allowance of carburized and quenched gears according to any one of claims 1 to 3, characterized in that: The calculation formula for obtaining the alignment amount according to the cumulative pitch deviation distribution is: In the formula: e is the positive quantity, F p is the cumulative total deviation of tooth pitch, and α is the gear pressure angle.

5. The method for optimizing the grinding allowance of carburized and quenched gears according to claim 4, characterized in that: The F p It is the average value of the total cumulative deviation of the tooth pitch on the left and right tooth surfaces of the gear.

6. The method for optimizing the grinding allowance of carburized and quenched gears according to claim 4, characterized in that: The gear pressure angle is 20°.

7. The method for optimizing the grinding allowance of carburized and quenched gears according to claim 1, characterized in that: After obtaining the secondary alignment result, the method further includes: re-turning the gear end face and inner hole reference band.

8. The method for optimizing the grinding allowance of carburized and quenched gears according to claim 1, characterized in that: After obtaining the gear pitch cumulative deviation distribution according to the starting teeth, the method further includes: screening out gears whose common normal line variation is greater than or equal to 50% of the maximum value of the grinding allowance.

9. The method for optimizing the grinding allowance of carburized and quenched gears according to claim 1, characterized in that: Determining the starting tooth of the gear includes: obtaining the number of teeth of the gear, taking one of the teeth of the gear as the starting tooth; and marking the position of the starting tooth on the gear.

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