Method for calculating service life of broach

Abstract

The invention discloses a broach service life calculation method. The method comprises the steps that 1, target gear parameters and broach parameters are determined; 2, calculating the nominal circular tooth thickness, and determining the single-tooth cutting meter number; determining a correction coefficient of the broach; 3, according to the parameters determined in the step 1 and the step 2, the single-time rated life of the broach is calculated; 4, according to the diameter of the addendum circle, the diameter of the root circle and the cross-rod distance, the broach sharpening frequency is obtained through calculation; and 5, calculating the rated total life of the broach according to the single rated life of the broach and the grinding times of the broach. According to the broach service life calculation method, reasonable and accurate calculation of new product machining cost is achieved, quota management of the service life of the broach is achieved, waste and unstable machining quality caused by unreasonable use of the broach can be effectively reduced, meanwhile, the relation between the machining efficiency and the machining cost can be conveniently calculated, and the service life of the broach is effectively improved. And flexible adjustment is carried out according to different product capacity requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of broach life detection, and in particular relates to a broach life calculation method. Background Art

[0002] There has been no calculation method that is more in line with the actual situation for the life of broaches. At present, there is no relevant parameter calculation in the industry, which has caused difficulties in the implementation of many tasks and confusion in use. 1) The use of broaches on site depends entirely on the experience of workers, the tool change standards are unclear, and they are selected at random, resulting in uneven use of broaches, which is not conducive to the rational and efficient use of broaches; 2) When implementing the three fixed indicators for on-site processing, there is no basis for the use of broaches, and it is impossible to effectively formulate on-site tool life quotas; 3) When quoting new products, due to the lack of such calculation methods and standards, it is impossible to effectively and reasonably estimate the processing costs, resulting in inaccurate calculations and large errors. Summary of the invention

[0003] The purpose of the present invention is to propose a broach life calculation method to solve the technical problems existing in the prior art that it is impossible to effectively formulate on-site tool life quotas and the calculation of early processing costs for trial production is inaccurate.

[0004] In order to achieve the above object, the present invention adopts the following technical solution:

[0005] A method for calculating the life of a broach comprises the following steps:

[0006] Step 1, determine the target gear parameters and broach parameters; the target gear parameters include the normal module m n , number of teeth Z1, helix angle β1, cutting width B, special structure, tooth top circle diameter d, tooth root circle diameter D, span M, workpiece hardness; the broach parameters include broach structure and broach coating;

[0007] Step 2: According to the normal modulus m n Calculate the nominal tooth thickness S, and determine the single tooth cutting length L based on the nominal tooth thickness S; determine the correction factor K when the broach is TiN coated t , Correction coefficient K when the broach adopts special structure j , Correction coefficient K of special structure of the processed gear teeth y ;

[0008] Step 3, calculating the single rated life n of the broach according to the parameters determined in steps 1 and 2;

[0009] Step 4, according to the tooth tip circle diameter d, tooth root circle diameter D, and span M determined in step 1, calculate the number of times C of broach sharpening;

[0010] Step 5, calculate the total rated life of the broach N according to the single rated life of the broach n and the number of broach grinding times C:

[0011] N=n×(C+1)

[0012] Where:

[0013] n——single rated life of broach, unit: piece;

[0014] C——Number of times the broach is sharpened, unit: times.

[0015] Furthermore, in step 2, the special structure is two-linked teeth, synchronizer 2.5 width small rectangular teeth or / and missing teeth.

[0016] Furthermore, in step 3, the calculation formula for the single rated life n of the broach is as follows:

[0017]

[0018] Where:

[0019] L——The number of meters cut by a single tooth of the broach, an evaluation index of the broach life, that is, the total length of the spline cut by a single broach tooth within one service life of the tool, unit: meter;

[0020] β1——Gear helix angle, unit: degree;

[0021] K t ——Correction factor when broaches are TiN coated;

[0022] K j ——Correction coefficient when the broach adopts special structure;

[0023] K y ——Correction coefficient of special structure of the gear teeth being processed;

[0024] B——Width of the broaching tooth of the workpiece, unit: mm;

[0025] Y——The hardness of the hole diameter of the workpiece before pulling. The value is taken as the median value of its range, unit: HB;

[0026] n——is the single rated life of the broach, unit: piece.

[0027] Furthermore, in step 4, the calculation formula for the number of broach grinding times C is as follows:

[0028] C=1.56×100[(d s -d x ), (D s -D x ), (M s -M x )]

[0029] Where:

[0030] d s ——Workpiece process requirements: upper deviation of tooth root circle diameter after broaching, unit: mm;

[0031] d x ——The lower deviation of the tooth root circle diameter after broaching required by the workpiece process, unit: mm;

[0032] D s ——Workpiece process requirements: upper deviation of the tooth tip circle diameter after broaching, unit: mm;

[0033] D x ——The lower deviation of the tooth tip circle diameter after broaching required by the workpiece process, unit: mm;

[0034] M s ——The upper deviation of the spline span after broaching required by the workpiece process, unit: mm;

[0035] M x ——The lower deviation of the spline span after broaching required by the workpiece process, unit: mm;

[0036] [c1, c2, c3] - Take the minimum value among the three values ​​​​c1, c2, and c3.

[0037] Compared with the prior art, the present invention has the following technical effects:

[0038] The broach life calculation method of the present invention realizes the reasonable and accurate calculation of the new product processing cost and the tool life quota management, thereby effectively reducing the waste caused by the unreasonable use of tools and the unstable processing quality. At the same time, it can conveniently calculate the relationship between processing efficiency and processing cost, and flexibly adjust according to different product production capacity requirements. This method can break through the inherent method of estimating based on experience (requiring professionals), is not restricted by work and technology, and anyone who needs data can calculate and evaluate tool life and other related data in the manner provided by the present invention. DETAILED DESCRIPTION

[0039] The present invention is further explained below with reference to the embodiments.

[0040] The present invention starts from the historical data of broach service life, eliminates abnormal usage data, constructs a broach life data set, and innovatively constructs a broach single rated life and rated total life calculation model based on the data change characteristics and the accumulated experience of operators, which can be used to guide new product development, quotation, and on-site broach use.

[0041] The broach life calculation method of the present invention is specifically formulated based on the life statistical data of M2 high-speed steel broaches used in spline tooth (including external splines and internal splines) broaching, and is used for production line tool life management and tool life quota calculation. Its basic requirements are as follows:

[0042] 1) Type of broach: involute, rectangular spline, triangular spline and other spline broaches.

[0043] 2) Tool material: M2 high speed steel.

[0044] 3) Coating material: None or TiN.

[0045] 4) Nominal round tooth thickness range S: 0.5-10mm.

[0046] 5)Broaching speed: 1-7m / min.

[0047] 6) Spline accuracy: GB / T 3478 level 6 to 7.

[0048] 7) Life value error: In mass production, a life value error less than ±15% should be a reasonable value. This range can be used as the basis for estimating the life of the broach and formulating the broach life quota.

[0049] 8) Others: The life calculation method described in this standard should be based on the stability of the tool, machine tool, and fixture system, and the tooth parameters meet the requirements of relevant standards.

[0050] The method of the present invention specifically comprises the following steps:

[0051] Step 1, determine the target gear parameters (as shown in Table 3) and broach parameters (as shown in Table 4). The target gear parameters include the normal module m n , number of teeth Z1, helix angle β1, cutting width B, special structure, tooth top circle diameter d, tooth root circle diameter D, cross-rod distance M, workpiece hardness; broach parameters include broach structure and broach coating. Among them, special structures include two-linked teeth, synchronizer 2.5 width small rectangular teeth, missing teeth, etc.

[0052] Step 2: According to the normal modulus m n Calculate the nominal tooth thickness S, and determine the single tooth cutting length L according to the nominal tooth thickness S (obtained from Table 1); determine the correction factor K when the broach is TiN coated t , Correction coefficient K when the broach adopts special structure j , Correction coefficient K of special structure of the processed gear teeth y ;

[0053] Step 3, calculate the single rated life n of the broach according to the parameters determined in steps 1 and 2.

[0054] Single rated life n: The total number of workpieces cut by a single broach tooth within one broach life cycle (i.e. each sharpening), unit: piece.

[0055]

[0056] Where:

[0057] L is the number of meters cut by a single tooth of a broach, which is an evaluation index of broach life. It refers to the total length of the spline cut by a single broach tooth within one service life of the tool (i.e. each sharpening), in meters (m).

[0058] β1——Gear helix angle, unit: degree (°).

[0059] K t ——Correction factor when broaches are TiN coated.

[0060] K j ——Correction coefficient when the broach adopts special structure.

[0061] K y ——Correction coefficient of special structure of the gear teeth being processed.

[0062] B——Width of the broaching tooth of the workpiece, unit: millimeter (mm).

[0063] Y——Hardness of the hole diameter of the workpiece before pulling. The value is taken as the median value of the range, unit: HB.

[0064] n——is the single rated life of the broach, unit: piece.

[0065] Table 1 Broach single tooth cutting length L range

[0066] S 0.5＜S≤3 3＜S≤4.5 4.5＜S≤6 6＜S≤8 8＜S≤10 L 25-28 26-29 28-32 25-28 22-27

[0067] Note: The cutting length L of a single tooth of the broach is selected according to the principle that the larger the nominal round tooth thickness S of the broach, the smaller the cutting length of a single tooth. For example: S=6.234, the cutting length L of a single tooth is selected as 28m.

[0068] Table 2 Recommended table of broach correction coefficients

[0069]

[0070] Step 4, according to the tooth top circle diameter d, tooth root circle diameter D, and span M determined in step 1, calculate the number of times C of broaching sharpening.

[0071] Number of broach grinding times C: The total number of normal grinding times when the broach has no abnormalities during use and reaches the single rated life state, unit: times.

[0072] C=1.56×100[(d s -d x ), (D s -D x ), (M s -M x )]

[0073] Where:

[0074] d s ——The workpiece process requires the upper deviation of the tooth root circle diameter after broaching, unit: mm.

[0075] d x ——The workpiece process requires the lower deviation of the tooth root circle diameter after broaching, unit: mm.

[0076] D s ——The workpiece process requires the upper deviation of the tooth top circle diameter after broaching, unit: mm.

[0077] D x ——The workpiece process requires the lower deviation of the tooth top circle diameter after broaching, unit: mm.

[0078] M s ——The workpiece process requires the upper deviation of the spline span (key width) after broaching, unit: mm.

[0079] M x ——The workpiece process requires the lower deviation of the spline span (key width) after broaching, unit: mm.

[0080] Specifically, the above six parameters can be obtained by considering the upper and lower tolerances of the tooth tip circle diameter d, tooth root circle diameter D, and cross-bar distance M obtained in step 1.

[0081] [c1, c2, c3] - Take the minimum value among the three values ​​​​c1, c2, and c3.

[0082] Step 5, calculate the rated total life N of the broach according to the single rated life n of the broach and the number of broach grinding times C.

[0083] Rated total life of broach N: the total number of workpieces processed by the entire broach when it meets the product process requirements, unit: piece.

[0084] N=n×(C+1)

[0085] Where:

[0086] n——single rated life of broach, unit: piece.

[0087] C——Number of times the broach is sharpened, unit: times.

[0088] Example:

[0089] Step 1: Determine the target gear parameters (as shown in Table 3) and broach parameters (as shown in Table 4).

[0090] Table 3 Target gear parameters

[0091]

[0092]

[0093] Table 4 Broach parameters

[0094] Broach structure Broach coating No small path centering No coating

[0095] Step 2: Determine the cutting length of a single tooth.

[0096] According to the normal modulus m n =3.96875, the nominal circular tooth thickness S is calculated to be 6.234, and the module range in Table 1, 6<S≤8 corresponding to the single tooth cutting meter L range is 25-28 meters, according to the normal module 3.96875, the calculated single tooth cutting meter S is 28 meters; look up Table 2 to get K t is 1, K j is 1, K y is 0.85.

[0097] Step 3: Calculate the single rated life of the broach according to formula (1):

[0098]

[0099] According to formula (2), the number of times the broach is sharpened is calculated:

[0100] C = 1.56 × 100 [(0.042-0), (0.1-0), (0.3-0)] = 6.55 ≈ 7 (times)

[0101] The rated total life of the broach is calculated according to formula (3):

[0102] N = 561 × (7 + 1) = 4488 (items)

[0103] Conclusion: The calculated single rated life of the broach is 561 pieces, the number of sharpenings is 7 times, and the total rated life is 4488 pieces.

[0104] From the above, the method for calculating the life of the broach of the present invention can obtain the result of the rated total life, realize the quota management of the tool life, and thus can effectively reduce the waste caused by the unreasonable use of the tool and the unstable processing quality. At the same time, it can conveniently calculate the relationship between the processing efficiency and the processing cost, and flexibly adjust according to the different product production capacity requirements. The reasonable and accurate calculation of the processing cost of new products is realized. This method can break through the inherent method of estimating based on experience (professional personnel are required), is not limited by work and technology, and anyone who needs data can calculate and evaluate the tool life and other related data in the manner provided by the present invention.

Claims

1. A method for calculating the life of a broach, characterized in that: The specific steps include: Step 1, determine the target gear parameters and broach parameters; the target gear parameters include the normal module m n , number of teeth Z1, helix angle β1, cutting width B, special structure, tooth top circle diameter d, tooth root circle diameter D, span M, workpiece hardness; the broach parameters include broach structure and broach coating; Step 2: According to the normal modulus m n Calculate the nominal tooth thickness S, and determine the single tooth cutting length L based on the nominal tooth thickness S; determine the correction factor K when the broach is TiN coated t , Correction coefficient K when the broach adopts special structure j , Correction coefficient K of special structure of the processed gear teeth y ; Step 3, calculating the single rated life n of the broach according to the parameters determined in steps 1 and 2; Step 4, according to the tooth tip circle diameter d, tooth root circle diameter D, and span M determined in step 1, calculate the number of times C of broach sharpening; Step 5, calculate the total rated life of the broach N according to the single rated life of the broach n and the number of broach grinding times C: N=n×(C+1) Where: n——single rated life of broach, unit: piece; C——Number of times the broach is sharpened, unit: times.

2. The broach life calculation method according to claim 1, characterized in that: In step 2, the special structure is two-linked teeth, synchronizer 2.5 width small rectangular teeth or / and missing teeth.

3. The broach life calculation method according to claim 1, characterized in that: In step 3, the calculation formula for the single rated life of the broach n is as follows: Where: L——The number of meters cut by a single tooth of the broach, an evaluation index of the broach life, that is, the total length of the spline cut by a single broach tooth within one service life of the tool, unit: meter; β1——Gear helix angle, unit: degree; K t ——Correction factor when broaches are TiN coated; K j ——Correction coefficient when the broach adopts special structure; K y ——Correction coefficient of special structure of the gear teeth being processed; B——Width of the broaching tooth of the workpiece, unit: mm; Y——The hardness of the hole diameter of the workpiece before pulling. The value is taken as the median value of its range, unit: HB; n——is the single rated life of the broach, unit: piece.

4. The broach life calculation method according to any one of claims 1 to 3, characterized in that: In step 4, the calculation formula for the number of broach grinding times C is as follows: C=1.56×100[(d s -d x ),(D s -D x ),(M s -M x )] Where: d s ——Workpiece process requirements: upper deviation of tooth root circle diameter after broaching, unit: mm; d x ——The lower deviation of the tooth root circle diameter after broaching required by the workpiece process, unit: mm; D s ——Workpiece process requirements: upper deviation of the tooth tip circle diameter after broaching, unit: mm; D x ——The lower deviation of the tooth tip circle diameter after broaching required by the workpiece process, unit: mm; M s ——The upper deviation of the spline span after broaching required by the workpiece process, unit: mm; M x ——The lower deviation of the spline span after broaching required by the workpiece process, unit: mm; [c1, c2, c3] - Take the minimum value among the three values ​​​​c1, c2, and c3.

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