High-precision concentric involute spline broach

Abstract

The utility model relates to a high-precision concentric involute spline broach which solves the technical problems that the broaching precision and the broaching speed of an existing broach cannot meet the requirements, or the manufacturing difficulty is high. The broaching tool comprises a front handle, a transition cone, a front guide section, a secondary guide section, a spline rough cutting tooth section, a spline guide tooth section, a spline fine cutting tooth section, a rear guide section and a rear handle which are sequentially connected from front to back, the secondary guide section is of a cylindrical guide structure, and the outer diameter size of the secondary guide section is in small tolerance fit with the bore diameter of a workpiece to be broached before broaching; the secondary guide section and the front guide section are in smooth transition; the spline rough cutting tooth section is of a gradual broaching structure; the spline fine cutting tooth section is of a conformal broaching structure; the spline guiding tooth section, the last row of rough cutting teeth of the spline rough cutting section teeth and the first row of fine cutting teeth of the spline fine cutting tooth section are aligned in the axial direction.

Description

Technical Field

[0001] The utility model relates to an internal spline broach, in particular to a high-precision concentric involute spline broach. Background Art

[0002] Designing internal splines in workpieces can make the gear system more compact and achieve a larger transmission ratio within a limited space. The existing process for machining internal splines is mainly broaching. Broaching is an efficient machining process that combines hobbing, shaving, and milling processes, and has been widely used in the automotive industry and other industrial fields. The broach used in broaching generally includes a front handle, a front guiding section, a rear guiding section, a rear handle, which are connected in sequence from front to back, and a cutting tooth structure arranged between the two guiding sections.

[0003] However, with the continuous improvement of the accuracy requirements for workpieces, the requirements for the broaching accuracy of internal splines in broaching are also continuously increasing. In addition, broaching is generally the first process in product production, and its broaching speed directly determines the efficiency of the entire production line. The broaching accuracy and broaching speed of the broach in the existing broaching process have gradually been unable to meet the current market requirements for production volume and delivery speed.

[0004] Chinese Patent CN214721059U discloses a powerful alignment involute spline broach, which includes a front handle part, circular cutting teeth, spline teeth, spline calibration teeth, and a rear handle part arranged from front to back. Among them, the front handle part and the circular cutting teeth are connected front and back, and the spline teeth, spline calibration teeth, and the rear handle part are connected in sequence front and back; a plurality of powerful alignment teeth are arranged between the front handle part and the circular cutting teeth; the front handle part, the circular cutting teeth, the powerful alignment teeth, the spline teeth, the spline calibration teeth, and the rear handle part are coaxial; and the joints of each part are smoothly transitioned. By setting the structure of the progressive rough cutting teeth and progressive finishing cutting teeth of the powerful alignment teeth and the spline teeth, the problems of too large concentricity between the minor diameter and the pitch circle of the internal spline and easy tooth surface scratching or tearing during high-speed broaching are effectively solved, the broaching efficiency and accuracy are improved, and the manufacturing cost is reduced at the same time. However, in the broach provided by this patent, the cutting teeth of the powerful alignment teeth and the spline teeth both adopt a negative rake angle structure, which has a high manufacturing difficulty and is not easy to machine.

[0005] Chinese Patent CN112222524 A discloses a high-precision involute spline broach and its design method, which includes a burnishing guiding tooth part. The burnishing guiding tooth part includes a plurality of concentrically arranged burnishing guiding tooth rings, and the burnishing guiding tooth rings are used to align the workpiece. The burnishing guiding tooth rings include a plurality of burnishing guiding teeth distributed in a ring shape. The synchronizer thin-walled workpiece processed by adopting this structure can eliminate more than 90% of the machining taper, improve the machining accuracy, and reduce the tooth profile error and runout. However, this patent is mainly designed for the technical problems of large cumulative tooth profile and large outer diameter runout after machining, and does not involve the relevant structural design for improving the broaching speed. Summary of the Utility Model

[0006] The object of the utility model is to solve the technical problems that the broaching accuracy and broaching speed of the existing broach cannot meet the requirements, or the manufacturing difficulty is relatively high, and to provide a high-precision concentric involute spline broach.

[0007] In order to achieve the above object, the technical solution provided by the utility model is as follows:

[0008] A high-precision concentric involute spline broach includes a front handle, a transition cone, a front guide section coaxially connected and arranged in sequence from front to back, and a rear guide section and a rear handle coaxially connected and arranged, and is characterized in that:

[0009] Between the front guide section and the rear guide section, a secondary guide section, a spline roughing tooth section, a spline guiding tooth section and a spline finishing tooth section are coaxially connected and arranged in sequence from front to back;

[0010] In order to improve the alignment accuracy of the broach, the secondary guide section is a cylindrical guide structure, and its outer diameter dimension has a small tolerance fit with the pre-broaching hole diameter of the workpiece to be broached, and its tolerance parameter is smaller than the tolerance parameter of the front guide section; the secondary guide section and the front guide section are smoothly transitioned;

[0011] The spline roughing tooth section is a generation-type broaching structure, and N c rows of roughing teeth are arranged along the circumferential direction, and N c is a natural number greater than 1, and each row of roughing teeth is used to cut out a part of the involute during the broaching process and gradually splice it into a complete tooth profile shape;

[0012] The spline finishing tooth section is a contour-type broaching structure, and N j rows of finishing teeth are arranged along the circumferential direction, and N j is a natural number greater than 1; the broaching allowance A j in the radial direction of the finishing teeth is greater than the broaching allowance A c in the radial direction of the roughing teeth;

[0013] In order to prevent the deflection of the workpiece caused by the different tool tooth structures during the conversion from the roughing teeth to the finishing teeth during the broaching process, a spline guiding tooth section is provided, and the spline guiding tooth section, the last row of roughing teeth of the spline roughing tooth section and the first row of finishing teeth of the spline finishing tooth section are axially tooth-aligned.

[0014] Further, the roughing teeth of the spline roughing tooth section satisfy the condition:

[0015] D c1 = D0 + 2S zc

[0016] D cl = D f - A j

[0017]

[0018] D cN = D c1 + 2S zc N

[0019] S nc = S nd - 2δ

[0020] Wherein, D c1 is the diameter of the first row of roughing teeth, D0 is the lower deviation of the diameter of the workpiece to be broached before broaching, and S zc is the tooth increment of the roughing teeth;

[0021] D cl is the diameter of the last row of roughing teeth, and D f is the upper deviation of the major diameter of the internal spline of the workpiece to be broached;

[0022] N c is the number of teeth of the roughing teeth; D cN is the diameter of the Nth row of roughing teeth, and N ranges from 2 to (N C - 1);

[0023] S nc is the tooth thickness of the roughing teeth, S nd is the upper deviation of the tooth thickness of the internal spline of the workpiece to be broached, and δ is the unilateral broaching amount of the tooth thickness of the finishing teeth. The value of δ is the same as that of A j ;

[0024] Furthermore, the finishing teeth of the spline finishing tooth section satisfy the conditions:

[0025] D j1 = D cl + 2S jc

[0026] D jl = D f

[0027]

[0028] D jM = D j1 + 2S jc M

[0029] S j1 = S nc + 2S jc

[0030] S jl = S nd

[0031] S jn = S j1+2S jc M

[0032] Among them, D j1 is the diameter of the first row of finish cutting teeth, and S jc is the tooth rise of the finish cutting teeth;

[0033] D jl is the diameter of the last row of finish cutting teeth;

[0034] N j is the number of teeth of the finish cutting teeth; D jM is the diameter of the M-th row of finish cutting teeth, and the value range of M is 2 to (N j -1);

[0035] S j1 is the tooth thickness of the first row of finish cutting teeth, S jl is the tooth thickness of the last row of finish cutting teeth, S jn is the tooth thickness of the M-th row of finish cutting teeth.

[0036] Furthermore, the secondary guiding section satisfies the condition:

[0037] L = [l0 + 2]

[0038]

[0039] Among them, L is the width of the secondary guiding section, l0 is the broaching length of the workpiece to be broached, and [] means rounding the result to the nearest integer; D y is the diameter of the secondary guiding section.

[0040] Furthermore, the spline guiding tooth section satisfies the condition:

[0041] D da = D cl - 1

[0042] D df = D0 - 1

[0043] S d = S nc - 0.05

[0044] l d = [l0 / 2]

[0045] Among them, D da is the addendum circle of the spline guiding tooth section, D df is the dedendum circle of the spline guiding tooth section, S d is the tooth thickness of the spline guiding tooth section, and l d is the width of the spline guiding tooth section.

[0046] Furthermore, the broaching allowance A of the finish cutting teeth in the radial direction jTake 0.1 - 0.15 mm.

[0047] Furthermore, the tooth rise amount S of the rough cutting teeth zc takes 0.03 - 0.05 mm; the unilateral broaching amount δ of the tooth thickness of the finish cutting teeth takes 0.1 - 0.15 mm.

[0048] Furthermore, the tooth rise amount S of the finish cutting teeth jc takes 0.015 - 0.025 mm.

[0049] The beneficial effects of the present utility model compared with the prior art:

[0050] 1. For a high-precision concentric involute spline broach of the present utility model, through the design of the form-generating spline rough cutting tooth section, the spline guiding tooth section, and the contour-type spline finish cutting tooth section, the broaching speed is increased from 2 - 4 m / min to 6 m / min, improving the broaching processing efficiency. The single-piece broaching beat is reduced from 2.5 min to 2 min, and the single-piece cost of the internal spline of the workpiece is reduced by 15%.

[0051] 2. For a high-precision concentric involute spline broach of the present utility model, through the design of the secondary guiding section and the spline guiding tooth section, it is ensured that the concentricity between the minor diameter of the internal spline of the workpiece after broaching and the pitch circle is less than 0.01 mm, ensuring the accuracy requirements of the precision measurement reference. The spline tooth profile accuracy is within 0.015 mm. While increasing the broaching speed, it is ensured that after broaching, parameters such as the high tooth profile, cumulative, minor diameter, and coaxiality of the internal spline of the workpiece meet the requirements. Description of the Drawings

[0052] Figure 1 is a schematic structural diagram of an embodiment of a high-precision concentric involute spline broach of the present utility model;

[0053] Figure 2 is a parameter schematic diagram of the secondary guiding section in the embodiment of the present utility model;

[0054] Figure 3 is a broaching schematic diagram of the spline rough cutting tooth section and the spline finish cutting tooth section in the embodiment of the present utility model.

[0055] The reference numerals in the drawings are explained as follows:

[0056] a - front handle; b - transition cone; c - front guiding section; d - secondary guiding section; e - spline rough cutting tooth section; f - spline guiding tooth section; g - spline finish cutting tooth section; h - rear guiding section; i - rear handle;

[0057] L - width of the secondary guiding section; D y - diameter of the secondary guiding section;

[0058] Z1 - rough cutting tooth allowance; Z2 - finish cutting tooth allowance. Detailed implementation mode

[0059] The following will further explain the specific technical solutions in the embodiments of the present utility model in conjunction with the accompanying drawings.

[0060] See Figure 1 , a high-precision concentric involute spline broach, including a front handle a, a transition cone b, a front guide section c, a secondary guide section d, a spline roughing tooth section e, a spline guiding tooth section f, a spline finishing tooth section g, a rear guide section h, and a rear handle i that are coaxially connected and arranged in sequence from front to back. That is, an incremental roughing and contouring finishing two-stage cutting structure is adopted, which improves the broaching speed while ensuring the broaching accuracy. The embodiments of the present utility model can also design standard spline calibration teeth according to the manual as needed.

[0061] See Figure 3 , in order to improve the broaching speed, an incremental roughing + contouring finishing structure is designed. The incremental roughing can remove most of the cutting allowance (Z1), and defects on the workpiece surface are allowed. The contouring finishing can strongly correct the defects generated by the incremental roughing during broaching (Z2). Also, because the broaching amount of the incremental roughing is only 0.05 - 0.15 mm in the tooth thickness direction, the broaching force is small, providing a basic condition for high-speed broaching.

[0062] Specifically, the embodiments of the present utility model are

[0063] The front handle a and the rear handle i adopt standard round broach handles.

[0064] The transition cone b and the front guide section c preliminarily align the position of the workpiece according to the traditional design method.

[0065] See Figure 2 , the secondary guide section d is a cylindrical guide structure, and its design purpose is to improve the alignment accuracy of the broach. Because directly improving the accuracy of the front guide section c will cause problems such as tool jamming. That is, after the front guide section c of the broach, a section of cylindrical guide structure is added. The size of this structure has a small tolerance fit with the pre-broaching hole diameter of the workpiece to be broached, and its tolerance parameter is smaller than that of the front guide section c (higher accuracy). It performs secondary alignment on the workpiece aligned by the front guide section c, strongly corrects the workpiece positioning, thereby improving the alignment accuracy, ensuring the concentricity between the pre-broaching hole diameter of the workpiece and the axis of the broach, and improving the accuracy of the final product after broaching. The secondary guide section d and the front guide section c have a smooth transition.

[0066] The spline roughing tooth section e is an incremental broaching structure and is the main cutting part (incremental roughing) of the broach spline. Its specific structure is that there are N c rows of roughing teeth, N cN is a natural number greater than 1. Each row of rough cutting teeth is used to cut out a part of the involute during the broaching process, gradually splicing into a complete tooth profile shape. The generation type rough cutting removes a large amount of metal parts that are not required for the spline during broaching, leaving only a small amount of allowance on its tooth profile part. The generation type rough cutting is easy to manufacture and the broach manufacturing cost is low, but the surface quality of the workpiece after broaching is slightly poor and the accuracy is relatively poor, so further broaching processing is required.

[0067] The fine cutting tooth section g of the spline is of the same-profile broaching structure. The fine cutting teeth are used to remove the remaining allowance left by the rough cutting teeth (same-profile fine cutting), and at the same time eliminate processing defects such as scratches and burrs generated by the rough cutting teeth, achieving the purpose of finishing and ensuring accuracy. Its specific structure is that N j rows of fine cutting teeth are arranged circumferentially. N j is a natural number greater than 1. The broaching allowance A j in the radial direction of the fine cutting teeth is greater than the broaching allowance A c in the radial direction of the rough cutting teeth. The same-profile fine cutting can improve the internal spline tooth profile accuracy of the workpiece after broaching, make up for the deficiencies of the generation type rough cutting, and shorten the total length of the broach, improving the broaching efficiency.

[0068] The spline guiding tooth section f is a guiding structure added between the spline rough cutting tooth section e and the spline fine cutting tooth section g to prevent the workpiece from deflecting due to different tool tooth structures during the conversion from rough cutting teeth to fine cutting teeth during broaching. The last row of rough cutting teeth of the spline guiding tooth section f, the spline rough cutting tooth section e, and the first row of fine cutting teeth of the spline fine cutting tooth section g are axially aligned.

[0069] The rear guiding section h is designed in a round hole shape for easy manufacturing.

[0070] The design process of the embodiment of the present utility model is as follows, where the units in the calculation part are all millimeters:

[0071] (1) Design of the generation type rough cutting

[0072] Among the N c rows of rough cutting teeth of the spline rough cutting tooth section e,

[0073] the diameter D c1 of the first row of rough cutting teeth = D0 + 2S zc , where D0 is the lower deviation of the pre-broaching hole diameter of the workpiece to be broached, and S zc is the tooth rise of the rough cutting teeth, generally taking 0.03 - 0.05 mm.

[0074] The diameter D cl of the last row of rough cutting teeth = D f - A j , where D f is the upper deviation of the internal spline major diameter size of the workpiece to be broached.

[0075] Number of roughing teeth Diameter D of the Nth row of roughing teeth cN = D c1 + 2S zc N, where the value range of N is 2 to N C - 1;

[0076] Tooth thickness S of roughing teeth nc = S nd - 2δ, where S nd is the upper deviation of the internal spline tooth thickness of the workpiece to be broached, and δ is the unilateral broaching amount of the finish-cut tooth thickness. The value of δ is the same as that of A j and generally takes 0.1 - 0.15 mm.

[0077] (2) Design of contour-type finish cutting

[0078] N of the finish-cut tooth section g of the spline j Among the N rows of finish-cut teeth,

[0079] Diameter D of the first row of finish-cut teeth j1 = D cl + 2S jc , where S jc is the tooth rise of the finish-cut teeth and generally takes 0.015 - 0.025 mm,

[0080] Diameter D of the last row of finish-cut teeth jl = D f ,

[0081] Number of finish-cut teeth Diameter D of the Mth row of finish-cut teeth jM = D j1 + 2S jc M, where the value range of M is 2 to N j - 1;

[0082] Tooth thickness S of the first row of finish-cut teeth j1 = S nc + 2S jc ,

[0083] Tooth thickness S of the last row of finish-cut teeth jl = S nd ,

[0084] Tooth thickness S of the Mth row of finish-cut teeth jn = S j1 + 2S jc M.

[0085] (3) Design of the secondary guiding section

[0086] The function of the cylindrical guiding structure is to enter the inner hole of the workpiece after preliminary alignment of the workpiece for secondary alignment.

[0087] The width L of the secondary guiding section d is L = [l0 + 2], where l0 is the broaching length of the workpiece to be broached, and [] represents rounding the result to the nearest integer;

[0088] The diameter of the secondary guiding section d That is, the tolerance parameter is ±0.005.

[0089] (IV) Design of the spline guiding tooth section

[0090] The addendum circle D of the spline guiding tooth section f da = D cl - 1,

[0091] The dedendum circle D of the spline guiding tooth section f df = D0 - 1;

[0092] The tooth thickness S of the spline guiding tooth section f d = S nc - 0.05;

[0093] The width l of the spline guiding tooth section f d = [l0 / 2].

[0094] (V) Design of the remaining parts

[0095] Combined with the traditional design method, complete the design of the remaining parameters of the broach provided in this embodiment (such as referring to the involute broach design part in the <Tool Design Manual> edited by Yuan Zhejun and Liu Huaming, published by China Machine Press).

[0096] The above are only the embodiments of the present invention, and do not limit the protection scope of the present invention. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, is included in the patent protection scope of the present invention. For those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirits of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-precision concentric involute spline broach, comprising a front handle (a), a transition cone (b), a front guiding section (c) coaxially connected and arranged in sequence from front to back, and a rear guiding section (h) and a rear handle (i) coaxially connected and arranged; characterized in that: Between the front guiding section (c) and the rear guiding section (h), a secondary guiding section (d), a spline rough cutting tooth section (e), a spline guiding tooth section (f), and a spline finish cutting tooth section (g) are coaxially connected and arranged in sequence from front to back; The secondary guiding section (d) is a cylindrical guiding structure, and its outer diameter dimension has a small tolerance fit with the pre-broaching hole diameter of the workpiece to be broached, and its tolerance parameter is smaller than the tolerance parameter of the front guiding section (c); there is a smooth transition between the secondary guiding section (d) and the front guiding section (c); The spline rough cutting tooth section (e) is a generation type broaching structure, and is provided with N c rows of rough cutting teeth along the circumferential direction, and N c is a natural number greater than 1; The fine broaching tooth section (g) of the spline is of a same-profile broaching structure, and is provided with N j rows of fine broaching teeth along the circumferential direction, and N j is a natural number greater than 1; the broaching allowance A j of the fine broaching teeth in the radial direction is greater than the broaching allowance A c of the rough broaching teeth in the radial direction; The spline guiding tooth section (f), the last row of rough cutting teeth of the spline rough cutting tooth section (e), and the first row of finish cutting teeth of the spline finish cutting tooth section (g) are axially tooth-aligned.

2. The high-precision concentric involute spline broach according to claim 1, characterized in that, The specific structure of the spline rough cutting tooth section (e) is: D c1 = D0 + 2S zc D cl = D f - A j D cN = D c1 + 2S zc N S nc = S nd - 2δ Among them, D c1 is the diameter of the first row of roughing teeth, D0 is the lower deviation of the diameter of the workpiece to be broached before broaching, and S zc is the tooth increment of the roughing teeth; D cl is the diameter of the last row of roughing teeth, D f is the upper deviation of the major diameter dimension of the internal spline of the workpiece to be broached; N c is the number of teeth of the rough cutting teeth; D cN is the diameter of the Nth row of rough cutting teeth, where N ranges from 2 to (N C - 1); S nc is the tooth thickness of the roughing teeth, S nd is the upper deviation of the tooth thickness of the internal spline of the workpiece to be broached, δ is the unilateral broaching amount of the tooth thickness of the finishing teeth, and the value of δ is the same as that of A j Same 3. A high-precision concentric involute spline broach according to claim 2, characterized in that, The specific structure of the spline finish cutting tooth section (g) is: D j1 = D cl + 2S jc D jl = D f D jM = D j1 + 2S jc M S j1 = S nc + 2S jc S jl = S nd S jn = S j1 + 2S jc M Among them, D j1 is the diameter of the first row of finish cutting teeth, and S jc is the tooth feed of the finish cutting teeth; D jl is the diameter of the last row of finishing teeth; N j is the number of fine cutting teeth; D jM is the diameter of the fine cutting teeth in the M-th row, where M ranges from 2 to (N j - 1); S j1 is the tooth thickness of the first row of finish cutting teeth, S jl is the tooth thickness of the last row of finish cutting teeth, S jn is the tooth thickness of the Mth row of finish cutting teeth.

4. A high-precision concentric involute spline broach according to claim 3, characterized in that: The secondary guiding section (d) satisfies the condition: L＝[l0+2] Wherein, L is the width of the secondary guiding section (d), l0 is the broaching length of the workpiece to be broached, [] represents rounding the result to the nearest integer; D y is the diameter of the secondary guiding section (d).

5. A high-precision concentric involute spline broach according to claim 4, characterized in that: The spline guiding tooth section (f) satisfies the condition: D da = D cl -1 D df = D0-1 S d = S nc - 0.05 l d ＝[l0 / 2] Among them, D da is the pitch circle diameter of the tooth tip of the spline guide tooth section (f), D df is the root circle diameter of the spline guide tooth section (f), S d is the tooth thickness of the spline guide tooth section (f), l d is the width of the spline guide tooth section (f).

6. A high-precision concentric involute spline broach according to claim 1, characterized in that: Roughing allowance A of finish cut teeth in the radial direction j Take 0.1 - 0.15 mm.

7. A high-precision concentric involute spline broach according to claim 2, characterized in that: Tooth rise amount S of roughing teeth zc Take 0.03 - 0.05 mm; The unilateral broaching amount δ of the finish cutting tooth thickness is 0.1 - 0.15 mm.

8. A high-precision concentric involute spline broach according to claim 3, characterized in that: Tooth rise amount S of fine cutting teeth jc Take 0.015 - 0.025 mm.

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