JP2000158230A - Broach - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform cutting by one cutting edge without contacting with a groove bottom face formed by the other cutting edge and restrain formation of a stress concentration part by letting the tooth crest of two cutting edges cooperate with each other, and forming a sectional form in which the groove bottom face and a pair of groove sides formed in a work are smoothly connected together. SOLUTION: A broach main body and a shell blade machining part are mounted on the same shaft, and roughing blade and groove bottom finishing blades as cutting edges and shell blades as different cutting edges from the former are provided side by side. In this case, in relation of the cutting edge form of a final cutting edge 120 within a plurality of groove bottom face finishing blades with the cutting edge form of a final finishing blade 122 for finally finishing a pair of groove sides 76 within a plurality of the shell blades, by letting the cutting edge face 72 of the final cutting edge 120 and the cutting edge face 70 of the final finishing blade 122 cooperate with each other, the groove bottom face 74 and a pair of the final groove sides 76 (between a pair of teeth) in a work 12 are formed into the sectional form of smooth connection actually without sharp angle parts therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broach for forming a groove in a work by giving a relative feed to the work while cutting the work.

[0002]

2. Description of the Related Art As a process for forming a groove, such as a key groove, a spline groove, a serration groove, and a gear tooth groove, on a work surface such as a flat surface, an inner cylindrical surface (inner hole surface), and an outer cylindrical surface of a work. Processing using a broach is already known. The broach includes a surface broach that forms a groove on the plane or outer cylindrical surface of the work, and an inner broach that forms a groove on the inner cylindrical surface of the work.

[0003] Japanese Patent Application Laid-Open No. Hei 10-202422 describes a conventional example of an inner surface broach. This broach is used to form an internal gear on a work.
This broach, as shown in FIG.
A plurality of first cutting blades are provided for cutting the workpiece 100 so that the depth of the groove bottom of the groove to be formed to 0 is sequentially increased. The plurality of first cutting blades include a plurality of rough blades 102 that perform cutting in the first half of a series of cutting operations, and a groove bottom surface finishing blade 103 that performs cutting in the second half and finishes the groove bottom surface. ing. This brooch is
Work 1 is designed so that the distance between the pair of groove side surfaces of the groove is gradually increased.
A plurality of shell blades 104 as a plurality of second cutting blades for cutting 00 are provided. The rough blade 102, the groove bottom finishing blade 103, and the shell blade 104 are formed side by side along the axis of the broach.

When using this broach, as shown in FIG. 1B, a rough blade 102 and a groove bottom finishing blade 103 are first applied to a work 100 by a rough blade 102 and a groove bottom finishing blade 103, and a pair of groove side surfaces 110, 110 is formed (indicated by “outside diameter ascending cutting” in the figure), and the shell blade 104 cuts a pair of groove side surfaces 110 formed by the rough blade 102 and the groove bottom surface finishing blade 103 later. Is performed (in the figure, "cut-to-thickness cutting"). In this broach, as shown in FIG. 5, the cutting edge surface 112 of the shell blade 104 is
3 is further away from the cutting edge surface 114,
The cutting by the shell blade 104 is performed without contacting the groove bottom surface 108 formed by the groove bottom surface finishing blade 103 prior thereto. Therefore, when this broach is used, cutting by the shell blade 104 is performed by the groove bottom surface finishing blade 1.
Unlike the case where the contact is performed while contacting the groove bottom surface 108 formed by the shell blade 03, the wear of the cutting edge of the shell blade 104 can be reduced, and the pair of groove side surfaces 110, 110 finished by the shell blade 104, ie, the pair of tooth surfaces Accuracy does not decrease.

[0005]

However, in this conventional broach, as shown in the drawing, a part of the fillet portion of each groove side surface 110 is cut off and a notch 116 is formed. Will occur. Here, notch 116
Is a portion that is recessed toward the work 100 with respect to each groove side surface 110 and has sharp corners. On the other hand, if the notch 116 can be prevented from being generated,
The strength of the portion of the work 100 where the groove is formed is improved. In other words, using the terminology of gears, the conventional broach would cause the tooth root to be cut down, but if this cutting down could be prevented, the strength of the gear would be improved.

[0006] Against this background, the present invention provides:
The object of the present invention is to optimize the relationship between the cross-sectional shape of the cutting edge of the first cutting edge and the cross-sectional shape of the cutting edge of the second cutting blade. According to the present invention, broaches of the following aspects can be obtained. Each mode is described in the same manner as in the claims, divided into sections, each section is numbered, and described in the form of citing the numbers of other sections as necessary. This is to facilitate understanding of some of the technical features and combinations thereof described in this specification, and the technical features and combinations thereof described in this specification are limited to the following embodiments. Should not be interpreted as

(1) A broach for forming a groove in a work by giving a relative feed to the work while cutting the work. The broach is formed so that the depth of the groove bottom surface of the groove is gradually increased. A plurality of first cutting blades for cutting;
A plurality of second cutting blades for cutting the work are formed side by side along the axis of the broach so that the interval between the pair of groove side surfaces of the groove is sequentially increased. And a tentative pair of groove side surfaces are formed, and later, the second pair of cutting edges are used to cut the tentative pair of groove side surfaces formed by the first cutting edge, thereby forming a final pair of groove surfaces. The side surface is formed, and the cutting edge by the second cutting edge is separated from the work by the cutting edge surface of the final cutting edge of the plurality of first cutting edges.
In the broaching performed without contacting the groove bottom surface formed by the first cutting edge, the first cutting edge and the second cutting edge cooperate with each other on the tip surfaces of the first cutting edge and the second cutting edge. Finally, a broach characterized in that the cross-sectional shape of the groove bottom surface and the pair of groove side surfaces formed in the work has a cross-sectional shape that is smoothly connected without substantially having sharp corners [ Claim 1]. According to this broach, the groove bottom surface and the pair of groove side surfaces are formed on the work so that their cross-sectional shapes are smoothly connected without substantially having sharp corners. Therefore, according to this broach, in order to perform the cutting by the second cutting edge without contacting the groove bottom surface formed by the first cutting edge, a sharp portion is formed in the fillet portion of the groove forming portion of the work. The formation of a stress concentration portion where stress tends to concentrate because of substantially having a corner portion is suppressed. For example, when the groove is a tooth groove, formation of a stress concentration portion at the root of the tooth is suppressed. Therefore, according to this broach, the strength of the portion of the work that forms the groove is improved. This broach can be a surface broach or an inner broach. Further, this broach can be a broach for full circumference processing or a broach for partial processing. (2) The first cutting edge and the second cutting edge cooperate with each other so that the first cutting edge and the second cutting edge cooperate with each other. The broach according to item (1), having a cross-sectional shape formed so that a side surface and the groove bottom surface are connected to each other by a substantially curved surface. (3) the relative feed includes at least a linear motion
Brooch according to paragraph (1) or (2). (4) A plurality of the grooves are formed on the inner surface of the hole formed in the work along the circumferential direction thereof, and the plurality of grooves form a plurality of tooth grooves. The broach according to any one of (1) to (3), wherein the broach is an inner broach. (5) The broach according to the above mode (4), wherein each tooth groove has a helix angle with respect to the axis of the hole, and the broach is a helical broach. (6) The broach according to any one of (1) to (5), wherein the first cutting blade and the second cutting blade are detachably attached to each other. (7) The first cutting edge includes a rough blade that performs cutting in the first half of a series of cutting operations, and the second cutting edge includes a shell blade. Brooch. (8) The tip surface of the final cutting edge is formed by a pair of final groove side surfaces to be formed by the plurality of second cutting edges and a groove bottom surface to be formed by the plurality of first cutting edges. Any one of (1) to (7) having a cross-sectional shape connected to each other without substantially having a concave portion on the work side with respect to a pair of extended surfaces obtained by extending the groove side surface toward the groove bottom surface; A broach according to claim 2 [claim 2]. According to this broach, in order to perform cutting by the second cutting blade without contacting the groove bottom surface formed by the first cutting blade, the fillet portion of the groove forming portion of the work has a pair of groove side surfaces and Substantially denting to the work side with respect to the pair of extension surfaces is prevented, and as a result, notch is prevented from being generated in the fillet. For example, when the groove is a tooth groove, it is possible to prevent the tooth root from being cut down. Therefore, according to this broach, the strength of the portion of the work that forms the groove is further improved. (9) The cutting edge surface of the final cutting edge is constituted by one arc surface substantially in contact with the final pair of groove side surfaces (8)
Brooch according to the paragraph. Here, the “arc surface” includes not only an arc whose cross section is an arc (a part of a perfect circle) but also a part whose ellipse is a part of an ellipse. (10) The cutting edge surface of each of the second cutting blades has a cross-sectional shape that smoothly connects the pair of groove side surfaces to be formed by each of the second cutting blades without substantially having sharp corners ( 1)
A broach according to any one of the above items (9) to (9). According to this broach, the roundness of the cutting edge surface of each second cutting blade is increased, and as a result, the life of each second cutting blade as a tool is prolonged. This broach is particularly desirable to be implemented in combination with the features described in the above item (8) or (9). (11) The cutting edge surface of the final cutting edge is constituted by one first arc surface substantially in contact with a final pair of groove side surfaces to be formed by the plurality of second cutting edges, and The cutting edge of the final finishing blade that performs cutting at the end of a series of cutting by the cutting edge, (a) on each of the final pair of groove side surfaces, each of the groove side surfaces and the first arc surface A pair of second arcuate surfaces substantially in contact with each other near the contact,
The broach according to any one of (1) to (10), wherein the broach has a radius shorter than the arc surface, and (b) a land surface substantially in contact with the pair of second arc surfaces. (12) A pair of first arcuate surfaces whose edge surfaces of the final cutting edge substantially contact a final pair of groove side surfaces to be formed by the plurality of second cutting blades are substantially in contact with them. The cutting edge surfaces of the final finishing blades configured to be connected to each other by one land surface and performing cutting at the end of a series of cutting by the plurality of second cutting blades are: (a) the final pair of groove side surfaces; A pair of second arcuate surfaces substantially contacting each other near each contact point between each groove side surface and each of the first arcuate surfaces, each having a shorter radius than each first arcuate surface; The broach according to any one of (1) to (10), comprising a pair of the second arc surfaces and a second land surface substantially in contact with the second arc surface.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a more specific embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 shows a broaching machine 14 for performing broaching on a work 12 using a broach 10 according to an embodiment of the present invention. In the present embodiment, the broach 10 is an inner broach, and the work 12 is an internal gear having a plurality of teeth arranged in the circumferential direction, and having a tooth tip curved surface inside the root bottom curved surface. .
One example of the internal gear is a ring gear in an automatic transmission of an automobile.

The broaching machine 14 is of a lead bar type, and has a lead bar 16 in parallel with the broach 10. The broach 10 and the lead bar 16 are attached to a frame 18 of the broaching machine 14 so as to be rotatable around respective axes and immovable in the axial direction. The broach 10 and the lead bar 16 are connected to each other by a gear train 22 as a connecting device, and the rotation of the drive-side lead bar 16 is transmitted to the broach 10, thereby causing the broach 10 to rotate around its axis. It is supposed to be.

The broaching machine 14 further includes a ram 24 for supporting the work 12 from below. A through hole is formed in the work 12 in advance. Brooch 10 is ram 24
Is pierced. The ram 24 is supported by the frame 18 so as to be movable in a direction parallel to the axis of the broach 10, but is prevented from rotating around the axis of the broach 10. A nut 30 is fixed to the ram 24. The nut 30 is screwed into a male screw formed on the surface of the lead bar 16.

The broaching machine 14 further includes a drive unit 3 for linearly moving the nut 30 along the lead bar 16.
2 is provided. The drive device 32 is configured to include an electric motor 34 as a drive source, a worm gear 36 as a first motion conversion mechanism, and a rack and pinion 38 as a second motion conversion mechanism. The electric motor 34 is fixed to the frame 18 such that its rotation axis crosses the lead bar 16 at right angles. The worm 40 is integrally rotatably attached to the rotation shaft. A worm wheel 42 is engaged with the worm 40. The worm wheel 42 is mounted on the frame 18
It is supported rotatably. The worm 40 and the worm wheel 42 cooperate with each other to form the worm gear 36. Worm wheel 4
A pinion 44 is attached to 2 so as to be integrally rotatable coaxially therewith. A rack 46 is engaged with the pinion 44. The rack 46 is supported by the frame 18 so as to be movable in a direction parallel to the lead bar 16. The nut 30 is fixed to the rack 46.

Accordingly, when the electric motor 34 is rotated, the worm 40, the worm wheel 42, and the pinion 44 are rotated, and the rotation of the pinion 44 causes the rack 46 to move linearly, and the linear movement causes the nut 30 to move linearly. Exercise. The linear motion of the nut 30 imparts a linear motion to the work 12 and also imparts a rotational motion via the gear train 22. As a result, the relative linear motion and the relative rotational motion are applied to the work 12 and the broach 10 together as a feed, whereby helical internal teeth are formed on the inner surface of the hole of the work 12. .

FIG. 3 shows the broach 10 in an enlarged manner. The broach 10 is configured such that a tubular shell blade processing portion 52 is detachably fitted to a broach body 50.

The broach body 50 includes a front grip 53, a guide 54, a plurality of rough blades 56, and a plurality of groove bottom finishing blades 5.
8 and a rear grip 59 are formed along the axis of the broach 10. Front grip 53 and rear grip 59
Is a portion held by the broaching machine 14, and the guide portion 54 is a portion guided by the broaching machine 14. The plurality of rough blades 56 and the groove bottom finishing blades 58 are portions for cutting the work 12 so that the depth of the groove bottom of the groove to be formed on the inner surface of the hole of the work 12 is sequentially increased. The diameter of the groove bottom of the work 12 is configured to increase as the position of the cutting edge surface of the groove bottom surface finishing blade 58 sequentially approaches the shell blade processing portion 52. The plurality of rough blades 56 and groove bottom finishing blades 58
It forms a line along a coaxial helix with the broach 10. Since the broach 10 is for full-periphery processing, a plurality of rows of rough blades 56 and groove bottom finishing blades 58 are formed side by side in the circumferential direction of the broach 10.

On the other hand, a plurality of shell blades 60 are formed in the shell blade processing section 52. Multiple shell blades 6
Numeral 0 is a portion for cutting the work 12 so that the distance between the pair of groove side surfaces of the grooves to be formed on the inner surface of the hole of the work 12 sequentially increases. It is configured to expand as the distance from the rough blade 56 and the groove bottom surface finishing blade 58 increases. Similarly to the plurality of rough blades 56 and the groove bottom finishing blades 58, the plurality of shell blades 60 are arranged in a line along a spiral coaxial with the broach 10. Since the broach 10 is used for processing the entire circumference, a plurality of rows of the shell blades 60 are formed side by side in the circumferential direction of the broach 10.

The rear end portion of the broach body 50 (the portion to which the rear grip portion 59 belongs) is inserted through the through hole of the shell blade processing portion 52. A sleeve 62 is inserted into a portion of the rear end protruding from the shell blade processing portion 52. The sleeve 62 is fixed to the broach main body 50 by fastening means such as screws, thereby preventing the shell blade processing portion 52 from being detached from the broach main body 50. The broach body 50 and the shell blade processing section 52 are keyed so that their relative rotation is allowed only within a certain limit.

As described above, the broach body 50 and the shell blade processing portion 52 are coaxially mounted. As a result, the broach 10 has a rough blade 56 as a first cutting blade and a groove bottom finishing blade 58. The shell blade 60 as the second cutting blade is formed side by side. When using this broach 10, first, the rough blade 56 and the groove bottom surface finishing blade 58
As a result, a groove bottom surface and a temporary pair of groove side surfaces are formed in the work 12, and the shell blade 60 later cuts the temporary pair of groove side surfaces formed by the rough blades 56, so that final cutting is performed. A pair of groove side surfaces is formed.

FIG. 1 shows the blade shape of the final cutting edge 120 (the rightmost groove bottom surface finishing blade 58 in FIG. 3) of the plurality of groove bottom surface finishing blades 58 in the broach 10, and the plurality of shell blades 60. The relationship with the blade shape of the final finishing blade 122 (the rightmost shell blade 60 in FIG. 3) that performs final finishing on the pair of groove side surfaces 76 is shown.

In this broach 10, the cutting edge surface 70 of each shell blade 60 has a final cutting edge 120
Are spaced apart from the cutting edge surface 72. Therefore, the cutting by each shell blade 60 is preceded by the final cutting edge 120
This is performed without contacting the groove bottom surface 74 (tooth bottom surface) formed in the work 12.

Further, in the broach 10, the cutting edge surface 72 of the final cutting blade 120 and the cutting edge surface 70 of the final finishing blade 122 form the workpiece 12 by cooperating with the final cutting blade 120 and the final finishing blade 122. The groove bottom surface 74 and a pair of final groove side surfaces 76 and 76 (a pair of tooth surfaces)
These cross-sectional shapes have a cross-sectional shape that has a smooth connection without substantially having sharp corners. Specifically, the work 12 has a pair of final groove side surfaces 7.
6, 76 are substantially curved surfaces (convex toward the groove bottom surface 74)
, And more specifically, the cutting edge surface 72 of the final cutting edge 120 is formed by a pair of groove side surfaces 7.
6, 76 substantially in contact with the first arc surface 80 (groove bottom surface 74).
(Convex toward). As a result, the cutting edge surface 72 of the final cutting blade 120 is moved to the final pair of groove side surfaces 7.
The pair of extension surfaces 78, 78 obtained by extending the grooves 6, 76 toward the groove bottom surface 74 is prevented from being recessed toward the workpiece 12. In addition, the sectional shape of the cutting edge surface 72 of the final cutting blade 120 (also the sectional shape of the groove bottom surface 74).
May be constituted not only by a single arc surface but also by a pair of arc surfaces connected to each other by a land surface.

On the other hand, the cutting edge surface 7 of each shell blade 60
Numeral 0 has a cross-sectional shape that smoothly connects the pair of groove side surfaces 76, 76 to be formed by the respective shell blades 60 and the groove bottom surface 74 without substantially having sharp corners. . In addition, the cutting edge surface 7 of the final finishing blade 122
0 indicates that (a) a pair of second arcuate surfaces 84, 84 (in the groove bottom surface 74) contacting each groove side surface 76 at a contact 82 where each groove side 76 and the first arc surface 80 substantially contact each other. And (b) a land surface 86 substantially in contact with the pair of second arc surfaces 84, 84, the radius r _{1 of which} is shorter than the radius r ₂ of the first arc surface 80. It is configured. Further, the blade shape (the overall cross-sectional shape of the shell blade 60) of the plurality of shell blades 60 excluding the final finishing blade 122 has a cross-sectional shape that is smaller than, but substantially similar to, the cross-sectional shape of the final finishing blade 122. (See “Cut-up of tooth thickness” in FIG. 4 (b).)

Therefore, according to the broach 10,
Prior to cutting by each shell blade 60, the final cutting blade 1
In order to carry out the process without contacting the groove bottom surface 74 formed in the work 12 by the work 20, a stress concentration portion where stress tends to concentrate due to a sharp angle in a fillet portion of the work 12 where a groove is formed. Is prevented from being formed.
That is, the formation of the stress concentration portion at the root of the internal gear is prevented. Therefore, this brooch 1
According to 0, the strength of the internal gear is improved.

Further, according to the broach 10, since the cross-sectional shapes of the groove bottom surface 74 and the pair of groove side surfaces 76, 76 formed on the work 12 are more rounded than before, the broach 10 The life as a tool is prolonged.

Further, according to the broach 10,
The fillet portion of the portion forming the groove in the work 12 is formed by a pair of final groove side surfaces 76 and 76 and a pair of extension surfaces 78 and 7.
8 is prevented from being recessed toward the work 12, and as a result, the tooth root of the internal gear is prevented from being cut down. Therefore, according to the broach 10, the strength of the internal gear is further improved.

Further, according to the broach 10,
The roundness of the cutting edge surface 70 of each shell blade 60 increases, and as a result,
The life of each shell blade 60 as a tool is prolonged.

As mentioned above, one embodiment of the present invention has been described in detail with reference to the drawings. However, this is merely an example, and the present invention provides the above-mentioned [Problems to be solved by the invention, means for solving the problem, and effects of the invention]. And various modifications and improvements based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 shows a relationship between a blade shape of a final cutting blade among a plurality of groove bottom finishing blades and a blade shape of a final finishing blade among a plurality of shell blades in a broach according to an embodiment of the present invention. It is a front sectional view for explanation.

FIG. 2 is a perspective view showing a broaching machine having the broach.

FIG. 3 is a side view showing the broach.

FIG. 4 is a side view showing a conventional broach,
It is a front sectional view for explaining outside diameter up grinding and tooth thickness up grinding using the broach.

FIG. 5 is a front view for explaining the relationship between the blade shape of the last cutting blade of the plurality of groove bottom finishing blades and the blade shape of the last finishing blade of the plurality of shell blades in the conventional broach. It is sectional drawing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Broach 12 Work 50 Broach main body 52 Shell blade processing part 56 Rough blade 58 Groove bottom finishing blade 60 Shell blade 70 Blade tip surface (shell blade) 72 Blade tip surface (final cutting blade) 74 Groove bottom surface 76 Groove side surface 78 Extension surface 82 Contact point

Claims (3)

[Claims] 1. A broach for forming a groove in a work by giving a relative feed to the work while cutting the work, wherein the work is cut so that the depth of the groove bottom surface of the groove is gradually increased. A plurality of first cutting blades, and a plurality of second cutting blades for cutting a workpiece such that the distance between a pair of groove side surfaces of the groove sequentially increases are formed along the axis of the broach, First, the first cutting edge forms a groove bottom surface and a temporary pair of groove side surfaces on the work, and the second cutting edge subsequently cuts the temporary pair of groove side surfaces formed by the first cutting edge. Is performed to form a pair of final groove side surfaces, and the cutting edge surface of the second cutting edge is separated from the work from the cutting edge surface of the final cutting edge of the plurality of first cutting edges. The cutting by the second cutting blade is
In the broaching performed without contacting the groove bottom surface formed by the cutting edge, the cutting edge surfaces of the first cutting edge and the second cutting edge are made to end by the first cutting edge and the second cutting edge cooperating with each other. A broach characterized in that a cross-sectional shape of a groove bottom surface and a pair of groove side surfaces formed in a work has a cross-sectional shape that is smoothly connected without substantially having sharp corners. 2. The cutting edge surface of the final cutting blade is provided with a plurality of second cutting edges.
A pair of extensions obtained by extending a pair of final groove side surfaces to be formed by the cutting blade and a groove bottom surface to be formed by the plurality of first cutting blades toward the groove bottom surface. The broach according to claim 1, having a cross-sectional shape connected to each other without substantially having a concave portion on the work side with respect to the surface. 3. The cutting edge surface of each of the second cutting blades has a cross-sectional shape that smoothly connects the pair of groove side surfaces to be formed by each of the second cutting blades without substantially having sharp corners. The broach according to claim 1 or claim 2.