JP2008036791A - Gear cutting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear cutting device capable of giving a sufficient torque to a work for gear and obtaining a high precision work for gear. <P>SOLUTION: The device includes a first center 20 fitted on one end of a rod-like work for gear 10A, a second center 30 fitted on the other end, and a rotary base 40A rotated together with the second center 30. In the axial middle of the work 10A, a flange 14A is provided with a knife edge 50 provided on the rotary base 40A biting thereinto. Provision of this flange 14A makes the rotational radius r1 long and the buckling length L1 short. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gear cutting device used when a gear is manufactured by a hob.

  Conventionally, various gear cutting devices that form teeth using a hob while rotating a rod-shaped gear material have been proposed. For example, a technology has been proposed in which center holes for fitting the center and the shaft body are provided on both end faces of the gear material, the shaft body is bitten into the inner wall of the center hole, and the gear material is rotated together with the center (Patent Literature). 1).

  However, in the technique described in Patent Document 1, since the distance (radius) between the rotation center of the shaft body and the support point between the shaft body and the gear material (center hole) is short, the rotational torque transmission efficiency is low. Unfortunately, it was necessary to set a large pressing load for pressing the center and the shaft body against the gear material. For this reason, an excessive pressing load acts on the gear material, which causes a problem that the gear material is bent (buckled).

  Accordingly, as shown in FIGS. 8 to 10, gear cutting apparatuses 100 and 200 that improve the transmission efficiency of rotational torque have been proposed. Gear cutting apparatuses 100 and 200 shown in FIGS. 8 and 10 are apparatuses for gear cutting a rod-shaped (shaft-shaped) gear material used as a pinion gear of a rack-and-pinion mechanism of an automobile steering. The gear material 101 used in the gear cutting device 100 is of a type provided with a recess 103 for press-fitting a torsion bar (not shown), and the gear material 201 used in the gear cutting device 200 is This is a type in which a recess for press-fitting a torsion bar is not provided. FIG. 9A is a plan view showing an end face of the gear base shown in FIG. 8 on the rotary base side, and FIG. 9B is a plan view showing an end face of the rotary base on the gear base side.

  The gear cutting apparatus 100 is fitted into a center 110 that fits into a center hole 102 formed at one end (upper end) of the gear blank 101 and a center hole 104 that is formed in a recess 103 at the other end (lower end). The center 120 and a rotating base 130 that rotates together with the center 120 and supports the gear material 101 are provided. The rotary pedestal 130 is provided with a torsion coil spring 131 for urging the center 120 in the direction of the gear material 101, and the end surface of the rotary pedestal 130 bites into the end surface of the gear material 101 to rotate the gear material 101. A knife edge 132 is provided for a face driver for transmitting the signal.

  The gear cutting apparatus 200 rotates together with a center 210 fitted into a center hole 202 formed at one end of the gear blank 201, a center 220 fitted into a center hole 204 formed at the other end, and the center 220. And a rotating pedestal 230 that supports the gear material 201. The rotating base 230 is provided with a torsion coil spring 231 for urging the center 220 in the direction of the gear material 201, and the end surface of the rotating base 230 bites into the end surface of the gear material 201 and enters the gear material 201. A knife edge 232 is provided for transmitting rotational torque.

In such gear cutting apparatuses 100 and 200, the distance from the rotation center of the gear materials 101 and 201 to the connection portion (rotation) is provided by providing the connection portions with the gear materials 101 and 201 around the centers 120 and 220. (Radius) r100, r200 can be made longer than before, and the transmission efficiency of the rotational torque to the gear materials 101, 201 can be improved. Note that r100 and r200 do not indicate the actual size of the radius, but merely indicate symbols.
JP-A-10-193221 (paragraph 0013, FIG. 1)

  However, in the conventional gear cutting apparatuses 100 and 200 shown in FIGS. 8 and 10, the transmission efficiency of the rotational torque can be improved, but since the gear materials 101 and 201 are rod-shaped (long), the center 110 , 210 (120, 220) to the center hole 102 (202), the pressing load F100 (F200) must be set large. When the pressing loads F100 and F200 are set large as described above, the rotational torque can be improved, but the residual strain applied to the gear materials 101 and 201 becomes large. As a result, there is a problem that even if the gear accuracy immediately after processing is good, the shafts of the gear materials 101 and 201 are bent due to the release of the residual strain after the heat treatment, so that the accuracy of the finished product is deteriorated. In addition, the gear material is buckled and deformed due to a large pressing load, and the center holes 102 and 104 are plastically deformed. There was also a problem that accuracy deteriorated.

  In the gear cutting apparatus 100 shown in FIG. 8, three knife edges 132 are provided at equal intervals in the circumferential direction as shown in FIG. 9B, and as shown in FIG. 9A. The shape of the end face 105 of the gear blank 101 that bites the knife edge 132 is uneven in the radial width depending on the location due to the jig for fixing the gear blank 101. Therefore, the knife edge 132 that bites in at the position of the width t1 and the knife edge 132 that bites in at the positions of the widths t2 and t3 have different biting depths, that is, the biting depth is inversely proportional to the width. The biting depth of the knife edge 132 at the positions t2 and t3 becomes deeper than the knife edge 132 at the position of the width t1, and as a result, the gear material 101 is inclined in the direction of arrow S, and the processing accuracy of the gear material 101 is increased. There was a problem of getting worse.

  In the conventional gear cutting apparatuses 100 and 200, the centers 120 and 220 are supported so as to be movable with respect to the rotary bases 130 and 230, so that the centers 120 and 220 and the concave parts of the rotary bases 130 and 230 Since there is a gap between them and they are only supported by the torsion coil springs 131 and 231, there is a problem that the centers 120 and 220 are rattled and the processing accuracy of the gear materials 101 and 201 is deteriorated. .

  The present invention solves the above-described conventional problems, and an object thereof is to provide a gear cutting device that can give a sufficient rotational torque to a gear material and obtain a highly accurate gear material. .

  The present invention includes a first center and a second center which are fitted in center holes formed on both end faces of a rod-shaped gear material and support the gear material so as to be displaceable in the axial direction, and the first center and the first center. A gear cutting device that rotates with at least one of the two centers and supports the gear material in the axial direction, wherein a gear is provided at an intermediate portion in the axial direction of the gear material. It is configured to support the part on the rotating base.

  According to this, since the distance between the rotation center portion of the gear material and the support point between the gear material and the rotation base can be increased by providing the flange portion, the transmission efficiency of the rotational torque to the gear material is increased. Can be improved. Further, since the collar portion is provided in the intermediate portion in the axial direction, the support length of the gear material can be shortened, so that buckling of the gear material can be prevented. Furthermore, the support point of the gear material can be set to three-point support of the first center, the second center, and the flange portion of the intermediate portion, and compared with the conventional two-point support (both ends support) of a pair of centers. Thus, the gear material can be stably supported.

  The present invention also includes a first center and a second center that are fitted in center holes formed on both end faces of a rod-shaped gear material and support the gear material so as to be displaceable in the axial direction, and the first center and the first center. A gear cutting device comprising: a rotating base that rotates together with at least one of the two centers and supports the gear material in an axial direction, wherein a ring portion having a uniform width in a radial direction is provided at an end of the gear material. The ring portion is configured to be supported by the rotating pedestal.

  According to this, by providing the ring portion having a uniform width, the pressing load of the gear material against the rotating base becomes uniform, and the inclination of the gear material at the time of gear cutting can be suppressed. As a result, it becomes possible to prevent plastic deformation of the center hole and buckling of the gear material.

  Further, the present invention is fitted with center holes formed on both end faces of a rod-shaped gear material, and rotates with at least one of the center, a pair of centers that support the gear material so as to be displaceable in the axial direction, A gear cutting device comprising: a rotating pedestal that supports a gear material in an axial direction, wherein the rotating pedestal includes an urging member that supports the center so as to be displaceable in the axial direction; The biasing member is configured such that one end of the biasing member is supported by the center and the other end is supported by the rotating base in a state in which a pressurized pressure is constantly applied toward the rotating direction of the rotating base. .

  According to this, rattling does not occur between the center and the rotating base, so that there is no deviation between the rotating shaft of the center and the rotating shaft of the gear material, and the machining accuracy can be improved.

  According to the present invention, it is possible to provide a gear cutting device capable of giving a sufficient rotational torque to a gear material and obtaining a highly accurate gear material.

  Hereinafter, a gear cutting apparatus according to an embodiment of the present invention will be described. The gear cutting devices 1A to 1C used in each embodiment are used as a material for a pinion gear of a rack and pinion mechanism of an automobile steering, and gear materials 10A and 10C in the gear cutting devices 1A and 1C. Is a type provided with recesses 12A and 12C for press-fitting a torsion bar (not shown), and the gear blank 10B used in the gear cutting device 1B has a recess for press-fitting the torsion bar. It is of a type that is not provided.

(First embodiment)
FIG. 1 is a partially cutaway cross-sectional view showing the gear cutting apparatus of the first embodiment.
The gear blank 10A used in the gear cutting apparatus 1A is formed in a substantially cylindrical shape so as to have a rod-like, that is, linear, rotating shaft 10m, and a tooth G1 is formed near a substantially central portion in the axial direction. It has an outer diameter portion 10a1. The teeth G1 of the outer diameter portion 10a1 are formed by cutting with a hob (cutter) (not shown) while rotating the gear blank 10A by a rotation mechanism described later. The same applies to the tooth G2 of the second embodiment.

  The gear material 10A has outer diameter portions 10b1 and 10c1 for fitting bearings on the upper and lower sides of the outer diameter portion 10a1, respectively, and a string between the outer diameter portion 10a1 and the outer diameter portion 10c1. A groove 10d1 that can be caulked by is formed.

  Further, the gear blank 10A is formed with a center hole 11A into which the first center 20 of the gear cutting apparatus 1A is fitted at one end (upper end surface) 10f1 in the axial direction. The center hole 11A has a substantially conical shape (standardized), and is formed so that the rotation axis 10m of the gear material 10A (center hole 11A) and the center axis 20m of the first center 20 coincide. Yes.

  Further, in the gear material 10A, a recess 12A that is hollowed in a hollow shape is formed on the end surface 10g1 of the outer diameter portion 10e1 located at the other end (lower end) in the axial direction, and the bottom portion (the illustrated ceiling portion) of the recess 12A is formed. ) Is formed with a center hole 13A into which the second center 30 of the gear cutting apparatus 1A is fitted. The center hole 13A has a substantially conical shape (standardized), and is set so that the rotation axis 10m of the gear material 10A (center hole 13A) and the center axis 30m of the second center 30 coincide. Yes.

  Further, the gear blank 10A is formed with a collar portion 14A protruding in the horizontal direction along the circumferential direction on the entire outer peripheral surface so as to divide the outer diameter portion 10c1 and the outer diameter portion 10e1 in an intermediate portion in the axial direction. Has been. In addition, the protrusion width | variety of this ridge part 14A to the radial direction is formed equally in any position. Moreover, the thickness of 14 A of collar parts can be changed suitably.

  The gear cutting apparatus 1A for gear cutting the gear material 10A described above includes a first center 20, a second center 30, and a rotating base 40A.

  The first center 20 has a tip (lower end) formed in a conical shape, and the tip is disposed toward one end side (upper end side) of the gear blank 10A. The first center 20 is driven in the axial direction by a drive mechanism (not shown), It fits into the hole 11A.

  The second center 30 has a tip (upper end) formed in a conical shape, and the tip is disposed toward the other end side (lower end side) of the gear material 10A. The second center 30 is fitted into the center hole 13A and rotated as described later. Together with the pedestal 40A, it is driven to rotate about the central axis 30m.

  The rotary pedestal 40A has a concave accommodation space 41 in which the second center 30 is accommodated. The housing space 41 is formed with housing portions 41a and 41b that are vertically cut into two cylindrical shapes having a large diameter and a small diameter. The diameter of the upper accommodating portion 41a is formed such that the outer diameter portion 10e1 of the gear material 10A can be inserted with a slight clearance. Further, the depth of the accommodating portion 41a is formed such that the end surface 10g1 of the outer diameter portion 10e1 does not hit the bottom 41a1 of the accommodating portion 41a when the gear blank 10A is supported by the rotary base 40A. The diameter of the lower accommodating portion 41b is formed such that the second center 30 can move in the vertical direction with a slight clearance. Also, in the accommodating portion 41b, a torsion coil spring 42 is accommodated in the lower portion of the second center 30, one end (lower end) 42a of the torsion coil spring 42 is supported by the bottom portion 41b1 of the accommodating portion 41b, and the other end (upper end). 42b is supported by the lower surface of the second center 30, and when the rotary pedestal 40A is driven to rotate, the second center 30 rotates together with the rotary pedestal 40A. The rotating pedestal 40A is configured to rotate around the central axis 30m by a driving mechanism (not shown).

  A plurality of knife edges 50 for transmitting rotational torque from the rotary base 40A to the gear material 10A are fixed to the rotary base 40A on the upper end surface 40a around the opening of the accommodating portion 41a. The knife edge 50 is called a face driver. For example, as shown in FIG. 5, the knife edge 50 is formed in a wedge shape and is arranged at three equal intervals in the circumferential direction. The set number of knife edges 50 is not limited to three and may be four or more.

  Next, a procedure for gear cutting of the gear material 10A by the gear cutting device 1A will be described. First, the first center 20 is fitted into the center hole 11A of the gear material 10A, and the center axis 20m of the first center 20 and the rotation axis 10m of the center hole 11A are made to coincide. Then, the first center 20 is moved together with the gear material 10A to the rotary pedestal 40A side, the second center 30 is fitted into the center hole 13A, and the center axis 30m of the second center 30 and the rotation axis 10m of the center hole 13A are Match. At the same time, the outer diameter portion 10e1 of the gear blank 10A is inserted into the accommodating portion 41a of the rotary base 40A with a slight clearance. When the gear blank 10A is further inserted, the lower surface 14a of the flange portion 14A comes into contact with the plurality of knife edges 50 provided on the upper end surface 40a of the rotary base 40A. Then, due to the pressing load F1 from the first center 20, each knife edge 50 bites into the lower surface 14a of the flange portion 14A, and the gear material 10A and the rotating base 40A are connected. At this time, the second center 30 sinks while receiving the urging force of the torsion coil spring 42 while being fitted into the center hole 13A. The torsion coil spring 42 receives the load from both the first center 20 and the second center 30 when the gear material 10A receives the pressing load F1 and the knife edge 50 bites into the flange portion 14A. It is set to be held in the received state. That is, as the torsion coil spring 42, a spring having such a spring property that the spring does not completely collapse when the knife edge 50 bites into the flange portion 14A is used. Note that the procedure for installing the gear material 10A in the processing apparatus is not limited to the above, and the second center 30 may be fitted into the center hole 13A of the gear material 10A first.

  As a result, the gear material 10A is connected to the rotating base 40A so as not to be relatively rotatable, and the gear material 10A rotates together by rotating the rotating base 40A. Then, the gear blank 10A is rotated and pressed while rotating the hob (cutter) to cut the outer diameter portion 10a1. When the gear cutting by the hob is completed, the first center 20 is moved backward by a drive mechanism (not shown) and the pinion gear obtained by gear cutting the gear material 10A is removed from the rotating base 40A.

  As described above, according to the gear cutting apparatus 1A of the first embodiment, the collar portion 14A is provided in the intermediate portion in the axial direction of the gear material 10A, and the collar portion 14A is connected to the rotary base 40A so as not to be relatively rotatable. By applying rotational torque to the gear material 10A, the distance from the rotating shaft 10m to the connection point between the gear material 10A and the rotation base 40A, that is, the rotation radius r1 when the gear material 10A is rotationally driven is larger than before. Therefore, it becomes possible to improve the transmission efficiency of the rotational torque from the rotating base 40A to the gear material 10A. Thereby, since the pressing load F1 applied to the gear material 10A can be reduced, it is possible to prevent buckling of the gear material 10A and plastic deformation of the center holes 11A and 13A.

  Further, this point will be described in detail. In FIG. 1, the pressing load is F1 (N), the rotating base 40A is T (Nm) for rotating the gear blank 10A, and the knife edge 50 is the end face 10g1 of the gear blank 10A. T = μ · F1 · r1 where r1 (m) is the distance (rotation radius) between the biting portion and the rotary pedestal 40A and the friction coefficient between the end surfaces of the knife edge 50 and the gear blank 10A is μ. The following relational expression holds. From this relational expression, assuming that the torque T required for gear cutting is constant, the friction coefficient μ is also constant, so that the pressing load F1 can be reduced by increasing the rotation radius r1.

  Therefore, by providing the flange 14A, the rotation radius r1 in the first embodiment shown in FIG. 1 can be made longer than the rotation radius r100 shown in FIG. 8, and the pressing load F1 in the first embodiment is shown in FIG. The pressing load F100 shown in FIG. Therefore, as described above, the buckling of the gear material 10A and the plastic deformation of the center holes 11A and 13A can be prevented.

  Further, as described above, the pressing load F1 can be made smaller than that of the conventional (pressing load F100), so that durability due to wear and fatigue of the knife edge 50 and the center hole 11A on the processing machine side can be improved. Further, in the conventional example shown in FIG. 8, since the end surface 105 of the gear material 101 is a connecting portion with the knife edge 132, it is necessary to improve the accuracy of the flatness of the end surface 105. In the first embodiment, Since the end face 10g1 of the gear material 10A is no longer required to be a connecting portion with the knife edge 50, it is not necessary to improve the accuracy of the flatness of the end face 10g1. As a result, if the end surface 10g1 is processed, it is difficult to perform the flat processing because of interference with the second center 30, but if the flange portion 14A is used, the flat processing is easy.

Further, when a buckling load (allowable buckling load) that can be allowed by the gear material 10A is Pcr (N), a relational expression of Pcr = (π ² EI) / 4L ² is established. E is the elastic modulus (N / mm ² ), I is the moment of inertia of the cross section (mm ⁴ ), and L is the pressing length (m). From this relational expression, the allowable buckling load Pcr can be increased by decreasing the pressing length L because the elastic modulus E and the secondary moment of inertia I are constant.

  Therefore, by providing the flange portion 14A, the pressing length L1 in the first embodiment shown in FIG. 1 can be shorter than the pressing length L100 shown in FIG. 8, and therefore the allowable buckling load in the first embodiment. Can be larger than the allowable buckling load shown in FIG. Therefore, the gear material 10A can be made to function in a direction to prevent buckling, and shaft runout at the time of gear cutting can be suppressed.

  Further, in the first embodiment, the conventional gear material 101 is supported at three points by adding a point at the position of the flange portion 14A to two points at the positions of the center holes 102 and 104 at both ends in the axial direction. Therefore, compared with the conventional two-point support (both-end support), the vibration width with respect to the cutting vibration that the gear blank 10A receives from the hob during gear cutting can be reduced. As a result, it is possible to suppress the axial deviation and inclination of both the central shafts 20m and 30m between the gear blank 10A and the processing machine side, and it is possible to improve the gear processing accuracy by gear cutting.

  FIG. 2 is a partially cutaway sectional view showing a modification of the gear cutting apparatus of the first embodiment. This gear cutting device 1B gears a gear material 10B of a type that is not provided with a recess for press-fitting a torsion bar. The gear material 201 shown in FIG. In addition, the second center 30B and the rotary base 40B on the processing machine side are changed, and the basic configuration is the same as that of the first embodiment. The outer diameter portions 10a2, 10b2, 10c2, 10d2, and 10e2 and the end surfaces 10f2 and 10g2 of the gear material 10B are the outer diameter portions 10a1, 10b1, 10c1, 10d1, and 10e1 and the end surfaces of the first embodiment shown in FIG. 10f1 and 10g1 are portions corresponding respectively to the gear material 10A in the first embodiment, and the shape thereof is slightly different.

  The flange portion 14B is formed to protrude in the shape of a disc along the outer peripheral surface so as to divide the outer diameter portion 10c2 and the outer diameter portion 10e2 in the intermediate portion in the axial direction of the gear material 10B.

  In the rotary base 40B, the connecting portion between the gear blank 10B and the knife edge 50 is located at the intermediate portion in the axial direction and the center hole 13B is formed in the end face 10g2, so the inner diameter of the accommodating portion 41c is shown in FIG. It is larger than the conventional one, and further, the axial length of the accommodating portion 41c is longer than the conventional one.

  The second center 30B is formed to have a larger shape as the diameter of the accommodating portion 41c increases, and is movable in the axial direction with a slight clearance. The torsion coil spring 42B is also formed with a large diameter based on the expansion of the shape of the second center 30B.

  In the case of the gear cutting device 1B, the first center 20 and the second center 30 are centered on the rotation shaft 10m in the center holes 11B and 13B of the gear blank 10B in the same manner as the gear cutting device 1A. The shafts 20m and 30m are fitted so as to coincide with the axial direction, and the outer diameter portion 10e2 of the gear material 10B is inserted into the accommodating portion 41c of the rotating base 40B with a slight clearance. When the gear blank 10B is further inserted, the lower surface 14b of the collar portion 14B comes into contact with the plurality of knife edges 50 provided on the upper end surface 40b of the rotary base 40B. And each knife edge 50 bites into the lower surface 14b of the collar part 14B by the pressing load F2 from the 1st center 20, respectively. The gear cutting by the hob is the same as described above. The torsion coil spring 42 in the second embodiment also has the gear material 10 </ b> C connected to the first center 20 when the gear material 10 </ b> C receives the pressing load F <b> 3 and the knife edge 50 bites into the end surface 15 a of the ring portion 15. The second center 30 is set so as to be held in a state where it receives a load from both sides.

  Also, in the case of the modification of the first embodiment, by providing the flange 14B, the rotation radius r2 shown in FIG. 2 can be obtained from the conventional rotation shown in FIG. Since it can be longer than the radius r200, the pressing load F2 can be made smaller than the conventional pressing load F200. Therefore, as described above, buckling of the gear material 10A and plastic deformation of the center holes 11A and 13A can be prevented.

Further, by providing the flange portion 14B, the pressing length L2 in the embodiment shown in FIG. 2 is compared with the pressing length L200 shown in FIG. 10 by the relational expression Pcr = (π ² EI) / 4L ² . Thus, the allowable buckling load in the modification of the first embodiment can be made larger than the allowable buckling load shown in FIG. Therefore, it can be made to function in the direction which prevents buckling of gear material 10B, and it becomes possible to control shaft runout at the time of gear cutting.

  Further, by providing the collar portion 14B, the diameter (dimension d2) of the second center 30B can be made larger than the diameter (dimension d200) of the conventional center 220 shown in FIG. The bending and buckling of the second center 30B can also be suppressed.

(Second Embodiment)
By the way, in the conventional gear cutting apparatus 100 shown in FIG. 8, the end surface 105 on the second center 30 side (lower side) of the gear material 101 is related to a jig for fixing the gear material 101 as shown in FIG. As shown in a), the widths t1, t2, and t3 are non-uniform (t1> t2 = t3) in the radial direction. Therefore, the knife edge 132 that bites in at the position of the width t1 and the knife edge 132 that bites in at the positions of the widths t2 and t3 cause a difference in the biting depth by the knife edge 132, and the knife edge at the position of the width t2 and t3. There is a problem that the biting depth 132 becomes deeper than the knife edge 132 at the position of the width t1, and the gear material 101 is inclined in the direction of the arrow S. As a result, the processing accuracy of the gear material 101 is deteriorated.

  As an embodiment for solving this problem, a second embodiment shown in FIGS. 3 and 4 will be described. FIG. 3 is a partially cutaway sectional view showing the gear cutting apparatus of the second embodiment, and FIG. 4 is a plan view showing the end face of the gear base used on the gear cutting apparatus of the second embodiment on the rotary base side. . The gear material 10C used here is the same as the gear material 10A except that the ring portion 15 is newly added without providing the collar portion 14A of the gear material 10A shown in FIG. The description is omitted. Further, the rotating base 40C includes an accommodating portion 41d cut in one step, and the second center 30 is accommodated in the accommodating portion 41d so as to be movable in the axial direction with a slight clearance.

  As shown in FIG. 4, the ring portion 15 in the second embodiment has a predetermined height and an end surface 15a having a uniform width t4 in the radial direction, and the knife edge 50 bites into the end surface 15a. Thus, the gear material 10C and the rotary base 40C are connected to each other so that rotational torque is transmitted to the gear material 10C.

  By providing the ring portion 15 having the uniform width t4 as described above, when the knife edge 50 is bitten into the gear material 10C at three locations as in the conventional case shown in FIG. Since the depth of biting into the end face 15a can be made uniform, the inclination at the time of processing the gear material 10C can be suppressed, and the processing accuracy of the gear material 10C can be improved.

  In the second embodiment, the second center 30 is supported so as to be movable with respect to the rotary pedestal 40C, and a gap e3 exists between the second center 30 and the accommodation space 41 of the rotary pedestal 40C. However, since it is only supported by the torsion coil spring 42, there is a problem that rattling occurs and the gear accuracy of the gear material 10C deteriorates. Therefore, hereinafter, a case where a means for solving the rattling problem (a configuration allowing only one-way rotation) is applied to the second embodiment will be described with reference to FIGS. 5 is an exploded perspective view showing a support mechanism for the second center and the rotating base, FIG. 6 is a cross-sectional view taken along the line AA in FIG. 5, and FIG. 7 is a cross-sectional view taken along the line BB in FIG.

  As shown in FIG. 5, the second center 30 is integrally formed with a conical portion 31 that fits into a center hole 13 </ b> A formed at the lower end of the gear material 10 </ b> C and a cylindrical portion 32 that extends below the conical portion 31. Has been configured. On the outer peripheral surface of the cylindrical portion 32 of the second center 30, concave spherical holes 32 a that can accommodate a part of the sphere 60 are formed at three positions that are equally divided in the circumferential direction (positions at intervals of 120 degrees). Furthermore, it is formed in a total of six locations for two rows in the axial direction. In addition, the curvature of the spherical hole 32a is formed slightly larger than the curvature of the spherical body 60 as shown in FIG. Further, the second center 30 shown in FIG. 5 corresponds to one center described in claim 3.

  On the other hand, on the side wall surface of the accommodation space 41 of the rotary base 40C, a concave groove 41s that can slide the sphere 60 is formed extending along the axial direction at a position corresponding to the spherical hole 32a. . Further, the curvature of the groove 41s is formed slightly larger than the curvature of the sphere 60 as shown in FIG.

  Further, a support hole 32b into which one end 42a of the torsion coil spring 42 is inserted is formed on the lower surface of the cylindrical portion 32, and a support hole 41t into which the other end 42b is inserted is formed, so that the second center 30 rotates. The base 40C is supported so as not to rotate.

  In the mechanism configured as described above, when the gear blank 10C is installed on the processing machine side, the center hole 13A of the gear blank 10C presses the tip of the second center 30 and receives the biasing force of the torsion coil spring 42. While moving downward. During the movement, each sphere 60 is in contact with both the spherical hole 32a of the second center 30 and the groove 41s of the rotating base 40C (see FIG. 6) and advances while rolling, so that the second center 30 moves smoothly up and down. I can move.

  However, if the second center 30 can easily rotate relative to the rotating pedestal 40C, the sliding mechanism of the groove 41s of the rotating pedestal 40C, the sphere 60, and the spherical hole 32a of the second center 30 A backlash occurs in the radial direction. Therefore, in the present embodiment, the second center 30 is constantly pressurized in the rotational direction indicated by the arrow W in FIG. 7 (the counterclockwise direction in the figure). That is, the second center 30 is inserted into and fixed to the support hole 32b and the support hole 41t by fixing the one end 42a and the other end 42b projecting in the direction opposite to the axial direction of the torsion coil spring 42. Rotational reaction force (counterclockwise direction) is received from the radial holes 32a, the spherical body 60, and the groove 41s. For example, the second center 30 and the rotating pedestal 40C always move up and down while maintaining the state shown in FIG. Also in this case, since the spherical body 60 can roll along the groove 41s, the smooth movement in the axial direction of the second center 30 is not impaired.

  Further, the torsion coil spring 42 has a property of expanding in the radial direction as it contracts in the axial direction, and the rotational reaction force increases. If this property is used, as the second center 30 is inserted into the inside (lower part) of the rotary pedestal 40C, the pressure is applied in the direction (arrow W direction in FIG. 7, counterclockwise direction). Further force is applied, further increasing the deterrence of rattling. In other words, there is no chance of rattling in a series of operations until the gear material 10C is installed at the tip of the second center 30 and the end face 15a of the gear material 10C is connected to the knife edge 50.

  In addition, although the case where the structure which permits only rotation in one direction is applied to the second embodiment has been described as an example, the present invention is not limited to this, and the first embodiment (FIG. 1) and its modifications are described. You may apply to (FIG. 2).

  Moreover, although the rotation pedestals 40A to 40C have been described by taking the embodiment that rotates together with the second centers 30 and 30B as an example, the rotation pedestals 40A to 40C may rotate together with the first center 20; It may rotate with both the centers 30 and 30B.

It is a partially cutaway sectional view showing the gear cutting device of the first embodiment. It is a partially cutaway sectional view showing a modification of the gear cutting apparatus of the first embodiment. It is a partially cutaway sectional view showing a gear cutting device of a second embodiment. It is a top view which shows the end surface by the side of the rotation base of the gear raw material used for the gear cutting processing apparatus of 2nd Embodiment. It is a disassembled perspective view which shows the support mechanism of a 2nd center and a rotation base. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a partially cutaway sectional view showing a conventional gear cutting apparatus. FIG. 9A is a plan view showing an end face of the gear base on the rotary pedestal side, and FIG. 9B is a plan view showing an end face of the rotary base on the gear base side. It is a partially cutaway sectional view showing another conventional gear cutting apparatus.

Explanation of symbols

1 gear cutting device 10A to 10C gear material 11A, 11B center hole 13A, 13B center hole 14A, 14B collar 15 ring part 20 first center 30, 30B second center 40A, 40C rotating base 42 torsion coil spring (biasing) Element)

Claims (3)

A first center and a second center which are fitted in center holes formed on both end faces of a rod-shaped gear material, and support the gear material so as to be displaceable in the axial direction;
A gear cutting device comprising: a rotating base that rotates together with at least one of the first center and the second center and supports the gear material in an axial direction;
A gear cutting apparatus characterized in that a collar portion is provided in an intermediate portion in the axial direction of the gear material, and the collar portion is supported by the rotary base. A first center and a second center which are fitted in center holes formed on both end faces of a rod-shaped gear material, and support the gear material so as to be displaceable in the axial direction;
A gear cutting device comprising: a rotating base that rotates together with at least one of the first center and the second center and supports the gear material in an axial direction;
A gear cutting apparatus comprising a ring portion having a uniform width in a radial direction at an end portion of the gear material, and the ring portion being supported by the rotating base. A pair of centers that fit with center holes formed on both end faces of the rod-shaped gear material, and support the gear material so as to be displaceable in the axial direction,
A gear cutting device comprising: a rotating base that rotates together with at least one of the centers and supports the gear material in an axial direction;
The rotating pedestal includes an urging member that supports the center so as to be displaceable in the axial direction, and the urging member is constantly applied with a pressure toward the rotation direction of the rotating pedestal. A gear cutting apparatus characterized in that one end thereof is supported by the center and the other end is supported by the rotating base.

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