JP5966655B2 - Extrusion mold, spline member manufacturing method, and spline member - Google Patents

Description

  The present invention relates to an extrusion mold used for manufacturing a spline member including a small-diameter portion that extends coaxially from a large-diameter portion and has a spline formed on an outer peripheral surface, and a spline member manufacturing method and spline using the same. It relates to members.

  Conventionally, as a manufacturing method for manufacturing hollow tooth-shaped parts each having a large-diameter portion and a small-diameter portion each having a tooth profile on the outer peripheral surface by cold forging, molding is performed with a punch inserted in the entire inner periphery of a cylindrical material. After the first step and the first step, a second forging step in which molding is performed at a molding pressure higher than the molding pressure in the first step in a state where at least a part of the inner peripheral surface of the cylindrical material is not opposed to the punch. (For example, refer to Patent Document 1). In this method, in the second step, a part of the inner peripheral surface of the cylindrical material is not opposed to the punch, so that when the molding is performed with a strong pressure, the surplus material does not face the punch. In the second step, molding is performed with sufficient pressure so as not to cause a lack of thickness while suppressing excessive pressure from being applied to the mold. Also, as a method of manufacturing a boss-equipped gear-like member in which a boss portion is formed on one side and a gear portion is formed on the other side with respect to the flange, the boss portion is subjected to backward extrusion on one end side of a metal material. Forming the chamfered portion by performing forward extrusion on the other end side of the metal material, and further performing forward extrusion on the remaining region of the metal material that has undergone the first step, A method including a second step of forming a gear portion in which a plurality of teeth are continuously formed from the chamfered portion toward one end side is known (for example, see Patent Document 2).

JP 2009-285688 A JP-A-2005-118789

  The hollow tooth component manufactured by the method described in Patent Document 1 has a cylindrical portion (straight portion) in which a tooth shape (spline) is not formed at the end portion of the small diameter portion on the large diameter portion side, If an attempt is made to secure the effective tooth length in the axial direction of the hollow tooth-shaped part, the axial length of the part will increase by the presence of the cylindrical portion. Therefore, in this type of member, in order to achieve compactness while ensuring the effective length of the teeth in the axial direction, the end face (flange) of the large diameter portion (flange) as in the gear-shaped member described in Patent Document 2 The surface) and the small diameter portion (tooth tip or tooth bottom) are preferably continuous with a curved surface. However, the more the radius of curvature of the curved surface connecting the end face of the large diameter portion and the small diameter portion is made to be small in order to ensure the effective length of the teeth in the axial direction, the more the material in the molded portion of the curved surface of the molding die is. As a result, it is difficult to follow, and as a result, there is a possibility that the whole tooth tip of each tooth of the small-diameter portion is lacking. If such a lack of tooth tip is generated, there is a risk that the strength will be reduced due to a decrease in effective tooth height, and the meshing target may be adversely affected due to an increase in surface pressure.

  Therefore, the present invention secures the effective length and strength of the spline satisfactorily while reducing the size of the spline member including the small diameter portion having the spline formed coaxially from the large diameter portion and formed on the outer peripheral surface. The main purpose.

  The extrusion mold, the spline member manufacturing method, and the spline member according to the present invention employ the following means in order to achieve the main object.

The extrusion mold according to the present invention is:
A large-diameter portion, a small-diameter portion extending coaxially from one end of the large-diameter portion and having a spline formed on the outer peripheral surface, a flange surface formed at the one end of the large-diameter portion and surrounding the small-diameter portion; An extrusion mold used when producing a spline member containing by extrusion molding,
A first molding surface for molding the outer peripheral surface of the large-diameter portion;
A second molding surface for molding the flange surface;
A third molding surface for molding the spline,
The inner diameter of the first molding surface is “D1”, the inner diameter between the tooth tips of the third molding surface is “d1”, the inner diameter between the tooth bottoms of the third molding surface is “d2”, and the third A radius of curvature of the first curved surface that makes the tooth tip of the molding surface and the second molding surface continuous is “R1”, and the second curved surface that makes the tooth bottom of the third molding surface and the second molding surface continuous. When the radius of curvature of “R2” is
R1> R2
0.25 × (D1-d1) / 2 ≦ R1 <0.48 × (D1-d1) / 2
0.09 × (D1-d2) / 2 ≦ R2 <0.37 × (D1-d2) / 2
It is characterized by satisfying.

  This extrusion mold includes a large-diameter portion, a small-diameter portion extending coaxially from one end of the large-diameter portion and having splines formed on the outer peripheral surface, and a small-diameter portion formed at one end of the large-diameter portion. It is used when a spline member including an enclosing flange surface is manufactured by extrusion molding. In such a spline member, in order to achieve compactness while ensuring the effective length of the spline, an inner curved surface in which the flange surface of the large diameter portion and the tooth bottom of the spline are continuous, or the tooth tip of the flange surface and the spline It is preferable to make the radius of curvature of the outer curved surface that keeps. However, the smaller the radius of curvature of the inner curved surface and the outer curved surface, the more difficult it is for the material to follow the first curved surface and the second curved surface which are the molding portions of the inner curved surface and the outer curved surface of the extrusion mold. As a result, the entire tooth tip of the spline is thinned, and there is a possibility that the strength of the spline may be reduced due to a decrease in effective tooth height.

  In view of such an event, the present inventors pay attention to the correlation between the curvature radius (design value) of the inner curved surface and the outer curved surface and the degree of lack of the tooth tip of the spline. By optimizing the radius of curvature of the outer curved surface, the spline member was made compact and the effective length of the spline was ensured, and at the same time, diligent research was carried out to reduce the splined tip of the spline. In addition, the present inventors have found that the difference (Δ1−δ1) / 2 between the radius Δ1 / 2 of the large diameter portion of the spline member and the radius δ1 / 2 of the root circle of the spline formed on the small diameter portion, and the spline member Of the spline tooth tip is evaluated by the difference (Δ1−δ2) / 2 between the radius Δ1 / 2 of the large diameter portion and the radius δ2 / 2 of the spline tip circle formed on the small diameter portion. The ratio ρ1 / (Δ1−δ1) / 2 between the radius of curvature ρ1 of the inner curved surface and the radius difference (Δ1−δ1) / 2 of the root surface, and the radius of curvature ρ2 of the outer curved surface and the tooth tip side A ratio ρ2 / (Δ1−δ2) / 2 with respect to the radius difference (Δ1−δ2) / 2 was determined as an evaluation index.

Here, since the spline member is manufactured by extrusion molding using an extrusion mold, the dimension of the spline member may be replaced with the dimension of the corresponding extrusion mold. The inner diameter of the first molding surface is “D1”, the inner diameter between the tooth tips of the third molding surface is “d1”, the inner diameter between the roots of the third molding surface is “d2”, and the teeth of the third molding surface The curvature radius of the first curved surface that connects the tip and the second molding surface is “R1”, and the curvature radius of the second curved surface that connects the tooth bottom of the third molding surface and the second molding surface is “R2”. If
Ratio ρ1 / (Δ1-δ1) / 2 = Ratio R1 / (D1-d1) / 2
Ratio ρ2 / (Δ1-δ2) / 2 = Ratio R2 / (D1-d2) / 2
Can be considered.

  And after obtaining the dimension of the spline member obtained from a plurality of extrusion molds with different specifications by analysis, the present inventors consider the tolerance in the extrusion mold and the spline member, and the ratio R1 / Based on (D1-d1) / 2 and ratio R2 / (D1-d2) / 2, etc., suitable ranges of the curvature radii R1, R2 of the first and second curved surfaces were examined. As a result, the inventors have R1> R2, 0.25 × (D1-d1) / 2 ≦ R1 <0.48 × (D1-d1) / 2, and 0.09 × (D1-d2) / By configuring the extrusion mold so as to satisfy 2 ≦ R2 <0.37 × (D1-d2) / 2, the radius of curvature of the inner curved surface and the outer curved surface is kept within a range where the spline member can be made compact. In addition, the present inventors have found that the effective length of the spline can be secured and the thickness of the spline tooth tip can be reduced. Thereby, if a spline member is manufactured by extrusion molding using this extrusion mold, the effective length and strength of the spline can be satisfactorily secured while the spline member is made compact.

  The extrusion mold may further include a molding portion for molding a non-penetrating small-diameter side recess in the small-diameter portion.

  As a result, during extrusion molding of the spline member, a non-penetrating small-diameter concave portion is formed in the small-diameter portion, and a non-penetrating small-diameter concave portion is formed in the small-diameter portion. It is possible to easily form a through hole penetrating the diameter portion and the small diameter portion.

A method for manufacturing a spline member according to the present invention includes:
A large-diameter portion, a small-diameter portion having a spline extending coaxially from the large-diameter portion and formed on an outer peripheral surface, and a flange surface formed at the one end of the large-diameter portion and surrounding the small-diameter portion. A spline member manufacturing method for manufacturing a spline member,
Extrusion metal mold having a first molding surface for molding the outer peripheral surface of the large-diameter portion, a second molding surface for molding the flange surface, and a third molding surface for molding the spline. Including an extrusion step of extruding the spline member using a mold,
The extrusion mold is
The inner diameter of the first molding surface is “D1”, the inner diameter between the tooth tips of the third molding surface is “d1”, the inner diameter between the tooth bottoms of the third molding surface is “d2”, and the third A radius of curvature of the first curved surface that makes the tooth tip of the molding surface and the second molding surface continuous is “R1”, and the second curved surface that makes the tooth bottom of the third molding surface and the second molding surface continuous. When the radius of curvature of “R2” is
R1> R2
0.25 × (D1-d1) / 2 ≦ R1 <0.48 × (D1-d1) / 2
0.09 × (D1-d2) / 2 ≦ R2 <0.37 × (D1-d2) / 2
It is characterized by satisfying.

  According to this method, the effective length and strength of the spline can be ensured satisfactorily while reducing the size of the spline member including the small diameter portion having the spline formed coaxially from the large diameter portion and formed on the outer peripheral surface. It becomes possible.

  The extrusion mold may further include a molding portion for molding a non-penetrating small-diameter side concave portion in the small-diameter portion, and the extrusion molding step is a material disposed in the extrusion-molding die. The large-diameter portion, the small-diameter portion, the spline, and the small-diameter-side concave portion may be formed while a non-penetrating large-diameter-side concave portion is formed in the large-diameter portion. .

  As a result, during extrusion molding of the spline member, a non-penetrating large-diameter side concave portion is formed in the large-diameter portion and a non-penetrating small-diameter side concave portion is formed in the small-diameter portion. By forming the non-penetrating large-diameter side concave portion or the small-diameter side concave portion, it is possible to easily form a through-hole penetrating both thereafter.

The spline member according to the present invention comprises:
Produced by extrusion molding, a large-diameter portion, a small-diameter portion that extends coaxially from the large-diameter portion and has a spline formed on the outer peripheral surface, and is formed at the one end of the large-diameter portion, the small-diameter portion A spline member including a surrounding flange surface,
The outer diameter of the large-diameter portion is “Δ1”, the diameter of the root circle of the spline is “δ1”, the diameter of the tip circle of the spline is “δ2”, and the root of the spline and the flange When the curvature radius of the inner curved surface that continues the surface is “ρ1”, and the curvature radius of the outer curved surface that continues the tooth tip of the spline and the flange surface is “ρ2”,
ρ1> ρ2
0.25 × (Δ1-δ1) / 2 ≦ ρ1 <0.48 × (Δ1-δ1) / 2
0.09 × (Δ1-δ2) / 2 ≦ ρ2 <0.37 × (Δ1-δ2) / 2
It is characterized by satisfying.

  This spline member is manufactured by extrusion molding using an extrusion mold as described above. Therefore, it is possible to replace the dimension of the extrusion mold with the dimension of the corresponding spline member, and ρ1> ρ2, 0.25 × (Δ1-δ1) / 2 ≦ ρ1 <0.48 × (Δ1-δ1). ) / 2, and 0.09 × (Δ1-δ2) / 2 ≦ ρ2 <0.37 × (Δ1-δ2) / 2, the spline effective length and strength can be reduced while achieving compactness. It becomes possible to ensure good.

  The spline member may be configured as a gear having gear teeth formed on an outer peripheral surface of the large diameter portion and a through hole penetrating the large diameter portion and the small diameter portion.

It is sectional drawing which shows the spline member 10 which concerns on the Example of this invention. 2 is a cross-sectional view showing an extrusion mold 20 used for manufacturing the spline member 10. FIG. FIG. 4 is a schematic diagram illustrating a manufacturing procedure of the spline member 10. FIG. 4 is a schematic diagram illustrating a manufacturing procedure of the spline member 10. FIG. 4 is a schematic diagram illustrating a manufacturing procedure of the spline member 10. FIG. 4 is a schematic diagram illustrating a manufacturing procedure of the spline member 10. It is sectional drawing which shows the spline member 10 comprised as the sun gear of a planetary gear. Analysis results of the dimensions of the mold models 1 to 3 used in the analysis for optimizing the specifications of the spline member 10 and the extrusion mold 20 and the dimensions of the spline members obtained from the mold models 1 to 3 It is a chart which shows.

  Next, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a spline member 10 according to an embodiment of the present invention. A spline member 10 shown in the figure is configured as a sun gear of a planetary gear included in a stepped automatic transmission (not shown), and includes a bottomed cylindrical large-diameter portion 11 and the large-diameter portion 11. A small-diameter portion 12 having a spline 120 that is coaxially extended from one end thereof and formed on the outer peripheral surface, and an annular flange surface 110 that is formed at one end of the large-diameter portion 11 and surrounds the small-diameter portion 12. The spline member 10 is manufactured by extrusion molding (cold forging) using an extrusion mold 20 as shown in FIG.

  As shown in FIG. 1, the large-diameter portion 11 has a non-penetrating large-diameter side recess 11h that opens upward in the drawing on its axis, and the outer peripheral surface has gear teeth by cutting after extrusion. (For example, a helical tooth) is formed. Further, as shown in FIG. 1, the small-diameter portion 12 includes a plurality of non-penetrating small-diameter-side concave portions 12 h that open downward in the drawing on the axial center, and a plurality of bottoms 120 d of the spline 120 and the flange surface 110. An inner curved surface 121 and a plurality of outer curved surfaces 122 that connect the tooth tips 120a of the splines 120 and the flange surface 110 are provided. That is, the spline member 10 is manufactured so as not to include a cylindrical portion (straight portion) where no spline is formed at the end portion of the small diameter portion 12 on the large diameter portion 11 side. In the embodiment, the boundary between the flange surface 110 and each inner curved surface 121 and the boundary between the flange surface 110 and each outer curved surface 122 are located on substantially the same circumference (see the downward arrow in FIG. 1), and the inner curved surface. The curvature radius (ρ1) of 121 is larger than the curvature radius (ρ2) of the outer curved surface 122 (ρ1> ρ2).

  As shown in FIG. 2, the extrusion mold 20 includes a first molding surface 21 for molding the outer peripheral surface (cylindrical surface) of the large-diameter portion 11 of the spline member 10 and a circle for molding the flange surface 110. An annular second molding surface 22, a third molding surface 23 for molding the spline 120, and a molding portion 24 for molding the small diameter side recess 12 h of the spline member 10 are included. Further, the extrusion mold 20 includes a plurality of first curved surfaces 231 that connect the tooth tips 230a of the third molding surface 23 (the portion forming the tooth bottom 120d of the spline 120) and the second molding surface 22; It includes a plurality of second curved surfaces 232 that make the tooth bottom 230d of the molding surface 23 (a portion forming the tooth tip 120a of the spline 120) and the second molding surface 22 continuous.

  In the embodiment, the boundary between the second molding surface 22 and each first curved surface 231 and the boundary between the second molding surface 22 and each second curved surface 232 are located on the same circumference (the downward arrow in FIG. 2). See), the radius of curvature (R1) of the first curved surface 231 is larger than the radius of curvature (R2) of the second curved surface 232 (R1> R2). When the spline member 10 is manufactured, as shown in FIG. 2, the extrusion mold 20 includes a movable first punch 31 capable of forming the large-diameter side recess 11 h of the large-diameter portion 11 and the large-diameter portion 11. 1 is used together with a movable second punch 32 whose upper end surface can be formed. The first punch 31 is inserted so as to be slidable in contact with the central hole of the second punch 32 formed in an annular shape with almost no gap and to be movable in the axial direction. Further, the second punch 32 is disposed so as to be movable in the axial direction in the extrusion mold 20 so as to be in sliding contact with the first molding surface 21 with almost no gap.

  FIGS. 3 to 6 are schematic views showing the manufacturing procedure of the spline member 10. In manufacturing the spline member 10, a material (metal material) 100 having a substantially cylindrical shape is placed on the second molding surface 22 as a material support surface of the extrusion mold 20, and then the material 100 is pressed (added). The pressure is applied to the first and second punches 31 and 32 as pressing members so that both are moved coaxially with respect to the extrusion mold 20. In the embodiment, as shown in FIG. 3, the first punch 31 is inserted into the center hole of the second punch 32 so as to protrude from the second punch 32 toward the material 100, and the first and second punches 31. , 32 is moved downward with respect to the extrusion mold 20 so that the distance G between the molding surfaces (end surfaces) facing the material 100 of the first and second punches 31, 32 is constant. The load is applied to both.

  As a result, as shown in FIG. 4, as the first punch 31 presses the material 100, a part of the material 100 (lower part in the drawing) causes the first and second curved surfaces 231, 232 of the extrusion mold 20. Or move along the upper edge of the molded part 24 between the third molded surface 23 and the molded part 24 (flow). Further, as the first and second punches 31 and 32 move relative to the extrusion mold 20, the second punch 32 also presses the material 100 as shown in FIG. As shown in FIG. 6, the molding of the spline member 10 as described above is completed when the first and second punches 31 and 32 have moved by a predetermined amount with respect to the extrusion mold 20.

  The spline member 10 thus manufactured is further subjected to cutting and the like, whereby the spline member 10 is configured as a sun gear (gear) of a planetary gear as shown in FIG. That is, the spline member 10 obtained by extrusion molding is subjected to cutting for forming the gear teeth 111 on the outer peripheral surface of the large diameter portion 11. Furthermore, the spline member 10 has the large-diameter portion 11 and the small-diameter portion 12 removed by cutting or pressing the portion between the large-diameter side recess 11h and the small-diameter side recess 12h (broken line portion in FIG. 7). A penetrating shaft insertion hole (through hole) 13 is formed. As can be seen from FIG. 7, the large-diameter side recess 11h and the small-diameter side recess 12h are formed in the large-diameter portion 11 and the small-diameter side recess 12h in the small-diameter portion 12 by extrusion molding. Therefore, the spline member 10 can form the shaft insertion hole 13 very easily. The inner diameters of the large-diameter side recess 11h and the small-diameter side recess 12h may be different from each other as shown in the figure, or may be the same.

  Here, in order to achieve compactness while ensuring the effective length of the spline 120 in the spline member 10 as described above, an inner curved surface in which the flange surface 110 of the large diameter portion 11 and the tooth bottom 120d of the spline 120 are continuous. It is preferable to make the radius of curvature of the outer curved surface 122 that connects the flange surface 110 and the tooth tip 120a of the spline 120 as small as possible. However, the smaller the curvature radius of the inner curved surface 121 and the outer curved surface 122 is, the more the first and second curved surfaces 231 and 232 that are the molded portions of the inner curved surface 121 and the outer curved surface 122 of the extrusion mold 20 are formed. The material 100 becomes difficult to follow, and as a result, the entire tooth tip 120a of the spline 120 is thinned, and the strength of the spline 120 may be reduced due to the reduction of the effective tooth height.

  In view of such an event, the present inventors pay attention to the correlation between the curvature radius (design value) of the inner curved surface 121 and the outer curved surface 122 and the degree of lacking of the tooth tip 120a of the spline 120. In addition, by optimizing the radii of curvature of the inner curved surface 121 and the outer curved surface 122, the spline member 10 is made compact while ensuring the effective length of the spline 120 and conducting earnest research to reduce the lack of the tip of the spline 120. It was. Upon such research, the present inventors have determined that the difference between the radius of the large-diameter portion 11 of the spline member 10 and the radius of the root circle of the spline 120 formed in the small-diameter portion 12, and the large-diameter portion 11 of the spline member 10. The degree of lacking of the tooth tip 120a of the spline 120 was evaluated by the difference between the radius and the radius of the tooth tip circle of the spline 120 formed in the small diameter portion 12.

  That is, the inventors set the outer diameter of the large diameter portion of the spline member 10 to “Δ1”, the diameter of the root circle of the spline 120 to “δ1”, and the tip of the spline 120 as shown in FIG. The diameter of the circle is “δ2”, the radius of curvature of the inner curved surface 121 that connects the root 120d of the spline 120 and the flange surface 110 is “ρ1”, and the outer surface that connects the tip 120a of the spline 120 and the flange surface 110 is continuous. When the curvature radius of the curved surface 122 is “ρ2”, the ratio ρ1 / of the curvature radius ρ1 of the inner curved surface 121 and the radius difference (Δ1−δ1) / 2 between the large diameter portion 11 and the root circle of the spline 120. Ratio [rho] 2 / ([Delta] 1- [delta] 2) of ([Delta] 1- [delta] 1) / 2, the radius of curvature [rho] 2 of the outer curved surface 122, and the radius difference ([Delta] 1- [delta] 2) / 2 between the large diameter portion 11 and the tip circle of the spline 120. / 2 was determined as an evaluation index .

Here, since the spline member 10 is manufactured by extrusion molding using the extrusion mold 20, the dimensions of the spline member 10 can be replaced with the dimensions of the corresponding extrusion mold 20. Accordingly, as shown in FIG. 2, the inner diameter of the first molding surface 21 of the extrusion mold 20 is “D1”, the inner diameter between the tooth tips 230a of the third molding surface 23 is “d1”, and the third molding surface. The inner diameter between the tooth bottoms 230d of 23 is “d2”, the radius of curvature of the first curved surface 231 connecting the tooth tip 230a of the third molding surface 23 and the second molding surface 22 is “R1”, and the third molding surface 23, if the radius of curvature of the second curved surface 232 connecting the tooth bottom 230d and the second molding surface 22 is “R2”,
Ratio ρ1 / (Δ1-δ1) / 2 = Ratio R1 / (D1-d1) / 2
Ratio ρ2 / (Δ1-δ2) / 2 = Ratio R2 / (D1-d2) / 2
Can be considered.

  And the present inventors prepared the mold models 1-3 of the extrusion mold from which a specification differs, and obtained the dimension of the spline member obtained from the said mold models 1-3 by analysis. FIG. 8 shows the specifications of the spline member 10 and the extrusion mold 20, that is, the radii of curvature ρ1, ρ2 of the inner curved surface 121 and the outer curved surface 122 of the spline member 10, and the first and second curved surfaces 231 of the extrusion mold 20. 232 Specifications of the mold models 1 to 3 used in the analysis for optimizing the radii of curvature R1 and R2, and the dimensions of the spline member (work) obtained from the mold models 1 to 3 (bottom of the spline) The FEM analysis values of the diameter δ1 of the circle and the diameter δ2 of the tip circle of the spline are shown. The mold models 1 to 3 basically have the same first to third molding surfaces, first and second curved surfaces, and molding parts as the above-described extrusion mold 20.

  As shown in FIG. 8, in the mold models 1 to 3, the inner diameter D1 of the first molding surface, the inner diameter d1 between the tooth tips of the third molding surface, and the inner diameter d2 between the tooth bottoms of the third molding surface are 40 respectively. The same values as 3 mm, 24.45 mm, and 27.2 mm were used. On the other hand, the curvature radii R1 and R2 in the mold models 1 to 3 are determined based on the fact that the smaller the curvature radii R1 and R2 of the first curved surface and the second curved surface in the extrusion mold, the easier the thinning of the spline 120 occurs. Different values were set as shown in FIG. The ratio R1 / (D1-d1) / 2 and the ratio R2 / (D1-d2) / 2, and the spline root circle obtained by FEM analysis, while taking into account tolerances in the extrusion mold and the spline member Based on the diameter δ1 of the spline and the diameter δ2 of the tip circle of the spline, suitable ranges of the radii of curvature R1 and R2 of the first and second curved surfaces 231 and 232 in the extrusion mold 20 were examined. At this time, the tolerance in the spline member 10 was ± 0.1 mm, and the tolerance in the extrusion mold was ± 0.02 mm.

When attention is paid to the mold model 3 shown in FIG. 8, the diameter d2 (mold dimension) of the tip circle of the third molding surface of the mold model 3−the diameter δ2 + of the tip circle of the spline + the tolerance in the extrusion mold = 27. 2−27.12 + 0.02 = 0.10, which is equal to the tolerance in the spline member 10. Based on this, the inventors set the values (2.0 and 0.625) of the curvature radii R1 and R2 of the first and second curved surfaces in the mold model 3 to the first and second of the extrusion mold 20. The lower limit values of the curvature radii R1 and R2 of the two curved surfaces 231 and 232 were determined. Thereby, as can be seen from FIG.
Ratio R1 / (D1-d1) /2≧0.25
Ratio R2 / (D1-d2) /2≧0.09
Is established, and by transforming these relational expressions,
R1 ≧ 0.25 × (D1-d1) / 2 (1)
R2 ≧ 0.09 × (D1-d2) / 2 (2)
The following relational expressions (1) and (2) can be obtained.

On the other hand, the larger the curvature radii of the first and second curved surfaces in the extrusion mold, the more advantageous for suppressing the lack of the spline 120, but the effective length of the spline 120 while reducing the size of the spline member 10. It is disadvantageous from the viewpoint of ensuring the security. For this reason, the present inventors do not form the length of the incomplete spline portion in the existing part (the axial length of the R portion at the end of the spline on the flange surface side or the axial length of the R portion and the spline. Based on the sum of the length of the cylindrical portion (straight portion), the radius of curvature R1 of the first curved surface is determined to be less than 3.75 (R1 <3.75). As described above, in the extrusion mold 20, the boundary between the second molding surface 22 and each first curved surface 231 (the boundary between the flange surface 110 and each inner curved surface 121), the second molding surface 22 and each Since the boundary with the second curved surface 232 (the boundary between the flange surface 110 and each outer curved surface 122) is located on the same circumference,
R2 = R1- (d2-d1) / 2 (3)
Thus, if “R1 = 3.75” in equation (3), then “R2 = 2.375”. For this reason, the inventors decided to set the radius of curvature R2 of the second curved surface to a value less than 2.375 (R2 <2.375).

Thus, the ratio R1 / (D1-d1) / 2 <3.75 / (40.3-24.45) / 2 and the ratio R2 / (D1-d2) / 2 <2.375 / (40 .3-24.45) / 2 is established,
R1 <0.48 (D1-d1) / 2 (4)
R2 <0.37 (D1-d2) / 2 (5)
The following relational expressions (4) and (5) can be obtained.

Therefore,
R1> R2
0.25 × (D1-d1) / 2 ≦ R1 <0.48 × (D1-d1) / 2
0.09 × (D1-d2) / 2 ≦ R2 <0.37 × (D1-d2) / 2
By configuring the extrusion mold 20 so as to satisfy the following three relational expressions, while keeping the curvature radii ρ1, ρ2 of the inner curved surface 121 and the outer curved surface 122 within a range in which the spline member 10 can be made compact, It will be appreciated that the effective length of 120 can be ensured and the lack of tooth tips 120a of the spline 120 can be reduced.

Further, as described above, since the spline member 10 is manufactured by extrusion molding using the extrusion mold 20, the dimension of the extrusion mold 20 can be replaced with the corresponding dimension of the spline member 10. it can. Therefore,
ρ1> ρ2
0.25 × (Δ1-δ1) / 2 ≦ ρ1 <0.48 × (Δ1-δ1) / 2
0.09 × (Δ1-δ2) / 2 ≦ ρ2 <0.37 × (Δ1-δ2) / 2
It will also be understood that the spline member 10 that satisfies the three relational expressions described above can satisfactorily ensure the effective length and strength of the spline 120 while achieving compactness.

  As described above, if the spline member 10 is manufactured by extrusion molding using the above-described extrusion mold 20, the spline member 10 can be made compact and the effective length and strength of the spline 120 can be ensured satisfactorily. It becomes possible to do. However, as long as the spline member that is the subject of the present invention includes a small-diameter portion that extends coaxially from the large-diameter portion and has a spline formed on the outer peripheral surface, the planetary gear finally has Needless to say, it is not limited to the sun gear. Further, the extrusion mold 20 may be used together with a punch in which the first and second punches 31 are integrated.

  Note that the correspondence between the main elements of the embodiment and the like and the main elements of the invention described in the section of the means for solving the problem is described in the section of the means for the embodiment etc. to solve the problem. The embodiment for carrying out the invention is an example for specifically explaining the embodiment, and does not limit the elements of the invention described in the column of means for solving the problem. In other words, the examples and the like are merely specific examples of the invention described in the column of means for solving the problem, and the interpretation of the invention described in the column of means for solving the problem is not limited to that column. This should be done based on the description.

  As mentioned above, although the embodiment of the present invention has been described using examples, the present invention is not limited to the above-described examples, and various modifications can be made without departing from the scope of the present invention. Needless to say.

  INDUSTRIAL APPLICABILITY The present invention can be used in the manufacturing industry of spline members including a small diameter portion that extends coaxially from a large diameter portion and has a spline formed on an outer peripheral surface.

  DESCRIPTION OF SYMBOLS 10 Spline member, 11 Large diameter part, 11h Large diameter side recessed part, 12 Small diameter part, 12h Small diameter side recessed part, 13 Shaft insertion hole, 20 Extrusion mold, 21 1st molding surface, 22 2nd molding surface, 23 3rd Molding surface, 24 molding part, 31 1st punch, 32 2nd punch, 100 material, 110 flange surface, 111 gear teeth, 120 spline, 120a tooth tip, 120d tooth bottom, 121 inner curved surface, 122 outer curved surface, 230a tooth tip , 230d tooth bottom, 231 first curved surface, 232 second curved surface.

Claims (4)

A large-diameter portion, a small-diameter portion extending coaxially from one end of the large-diameter portion and having a spline formed on the outer peripheral surface, a flange surface formed at the one end of the large-diameter portion and surrounding the small-diameter portion; An extrusion mold used when producing a spline member containing by extrusion molding,
A first molding surface for molding the outer peripheral surface of the large-diameter portion;
A second molding surface for molding the flange surface;
A third molding surface for molding the spline,
The inner diameter of the first molding surface is “D1”, the inner diameter between the tooth tips of the third molding surface is “d1”, the inner diameter between the tooth bottoms of the third molding surface is “d2”, and the third A radius of curvature of the first curved surface that makes the tooth tip of the molding surface and the second molding surface continuous is “R1”, and the second curved surface that makes the tooth bottom of the third molding surface and the second molding surface continuous. When the radius of curvature of “R2” is
R1> R2
0.25 × (D1-d1) / 2 ≦ R1 <0.48 × (D1-d1) / 2
0.09 × (D1-d2) / 2 ≦ R2 <0.37 × (D1-d2) / 2
An extrusion mold characterized by satisfying: In the extrusion mold according to claim 1,
An extrusion mold, further comprising a molding portion for molding a non-penetrating small-diameter-side concave portion in the small-diameter portion. A large-diameter portion, a small-diameter portion having a spline extending coaxially from the large-diameter portion and formed on an outer peripheral surface, and a flange surface formed at the one end of the large-diameter portion and surrounding the small-diameter portion. A spline member manufacturing method for manufacturing a spline member,
Extrusion metal mold having a first molding surface for molding the outer peripheral surface of the large-diameter portion, a second molding surface for molding the flange surface, and a third molding surface for molding the spline. Including an extrusion step of extruding the spline member using a mold,
The extrusion mold is
The inner diameter of the first molding surface is “D1”, the inner diameter between the tooth tips of the third molding surface is “d1”, the inner diameter between the tooth bottoms of the third molding surface is “d2”, and the third A radius of curvature of the first curved surface that makes the tooth tip of the molding surface and the second molding surface continuous is “R1”, and the second curved surface that makes the tooth bottom of the third molding surface and the second molding surface continuous. When the radius of curvature of “R2” is
R1> R2
0.25 × (D1-d1) / 2 ≦ R1 <0.48 × (D1-d1) / 2
0.09 × (D1-d2) / 2 ≦ R2 <0.37 × (D1-d2) / 2
The spline member manufacturing method characterized by satisfying the above. In the manufacturing method of the spline member according to claim 3,
The extrusion mold further includes a molding part for molding a non-penetrating small-diameter side recess in the small-diameter part,
The extrusion molding step forms the large-diameter portion, the small-diameter portion, the spline, and the small-diameter-side concave portion by pressurizing a material arranged in the extrusion-molding die with a pressing member. A non-penetrating large-diameter side recess is formed in the spline member manufacturing method.

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