JP2849981B2 - Molding method of metal molded article having toothed ridges with missing tooth regions - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method for molding a metal molded article having tooth-shaped ridges such as splines and gear teeth having a missing tooth region. INDUSTRIAL APPLICATION This invention is applicable to the gear component used for the transmission of vehicles, for example.

[0002]

2. Description of the Related Art A gear part 1 (see FIG. 12) used for a vehicle transmission, for example, is known as a metal molded product having a toothed ridge. On the outer peripheral portion of the gear component 1, a number of splines 14 are arranged in rows at intervals in the circumferential direction. In the gear component 1, a region where the spline 14 is not formed, that is, a missing tooth region is provided. The missing tooth region is used, for example, for forming an oil hole.

[0003] When such a gear component 1 is forged, as shown schematically in FIG. 13, a cylindrical carbon steel rough material 700 and a die 200 having a die hole 201 are formed.
And a mandrel 400 substantially coaxially arranged in the die hole 201 of the die 200. And punch 5
50, the die hole 2 of the die 200
The cylindrical raw material 700 is forcibly pressed by a punch 550 into a ring-shaped gap between the inner peripheral portion of the inner member 01 and the outer peripheral portion of the mandrel 400.

As a result, the die hole 20 of the die 200 is formed.
In the gap of the forming groove 270 formed in the inner peripheral portion
The material portion of the rough shaped material 700 flows in, and the plurality of splines 14 described above are formed.

[0005]

However, in the gear component 1 described above, as described above, the spline 14
There is a missing tooth region where no is formed. In such a missing tooth region, there is no gap defined by the formed groove 270. For this reason, when the spline 14 is formed by performing the indentation as described above, a portion of the material corresponding to the missing tooth becomes excessive near the missing tooth region. Therefore, during the above-described pushing, the excess material that has lost its place to flow flows in the pushing direction and gathers on the rear side as shown in FIG. This burr M is not preferable because it is crushed by the mold surface 200k of the die 200 at the last stage of pushing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of forming a metal molded product capable of suppressing the generation of burrs near a missing tooth region in the metal molded product.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method of forming a metal molded product having a tooth-shaped projection having a toothless region, the method comprising the steps of: It is a method of obtaining a metal molded product having a plurality of toothed ridges extending in parallel with the axial direction and having a toothless region where there are no toothed ridges at predetermined positions in the circumferential direction. A metal rough part to be formed, a die having a die hole and defining an outer peripheral part of the coarse part, and a mandrel arranged substantially coaxially in a die hole of the die and defining an inner peripheral part of the coarse part, A forming groove group formed of a number of forming grooves formed on one of the inner peripheral portion of the die hole and the outer peripheral portion of the mandrel and extending in a direction parallel to the axial length direction to form tooth-shaped ridges of a metal molded product; Are formed on the other of the inner peripheral portion of the die hole and the outer peripheral portion of the mandrel, and are adjacent to each other in the circumferential direction. And a relief groove provided at a position corresponding to the missing tooth region in the circumferential direction and located in the direction opposite to the recess direction of the group of formed groove grooves in the radial direction. A cylindrical coarse material is strongly pressed into the ring-shaped gap between the inner peripheral portion of the hole and the outer peripheral portion of the mandrel by a punch, and the outer peripheral portion and the inner peripheral portion of the coarse material are formed by a group of forming grooves. On one side, a large number of toothed ridges extending in a direction parallel to the axial length direction are formed, and the flesh portion of the coarse material corresponding to the missing tooth region is caused to flow into the escape groove, and the excess thickness relief projection is formed. And a removing step of cutting and removing a surplus relief projection of the intermediate molded body taken out of the die to obtain a metal molded product. .

[0008]

According to the method of the present invention, in the pressing step, a cylindrical coarse material is strongly pressed by a punch into a ring-shaped gap between the inner peripheral portion of the die hole of the die and the outer peripheral portion of the mandrel. Push in. As a result, the material of the crude material flows into the space defined by the forming groove. Therefore, by the forming groove,
A large number of splines and tooth-shaped ridges such as gear teeth are formed on one of the outer peripheral portion and the inner peripheral portion of the crude material.

According to the method of the present invention, in the pushing step,
An extra portion of the material of the rough section corresponding to the missing tooth region flows into the groove. The material that flows into the groove,
It becomes a protrusion to release excess meat. As a result, an intermediate molded body provided with a protrusion for releasing excess metal is formed. In the removing step, the excess metal relief protrusion of the intermediate molded body taken out of the die is cut and removed to form a metal molded product.

[0010]

EXAMPLES Examples of the molding method of the present invention will be specifically described. First, the gear component 1 as a metal molded product will be described with reference to FIG. The gear component 1 is the same as the gear component described in the related art, is used for an automatic transmission of an automobile, and is made of carbon steel.

As shown in FIG. 12, the gear component 1 has a cylindrical body 10, a flange 11 extending integrally with the cylindrical body 10 in the centrifugal direction, and a large-diameter cylinder extending from the flange 11 in the axial direction. State body 12. The large-diameter cylindrical body 12 is coaxial with the cylindrical body 10 and is larger in diameter than the cylindrical body 10. In this embodiment, the intermediate molded body 8 to be the gear component 1 is molded. FIG. 1 shows a main part of the intermediate molded body 8. FIG.
Indicates the bottom surface of the intermediate molded body 8. The intermediate molded body 8 has a shape substantially similar to the gear component 1. Here, the intermediate formed body 8 includes a large number of splines 14 and a surplus relief projection 80 described later. The inner peripheral portion 8i of the intermediate molded body 8 including the excess thickness relief projection 80 is cut and removed at a predetermined depth over the entire circumference to obtain the gear component 1.

That is, as shown in FIG. 1, a spline 14 as a tooth-like ridge is formed on the outer peripheral portion of the intermediate molded body 8. A large number of splines 14 (a total of 47 teeth including missing teeth; four missing teeth) are arranged at intervals along the circumferential direction of the intermediate molded body 8, that is, in the direction of the arrow R <b> 1. As can be understood from FIG. 1, the spline 14 has a substantially trapezoidal cross section, and extends in the axial direction of the intermediate molded body 8 serving as the gear component 1, that is, in the direction of the arrow P <b> 1. As can be understood from FIG. 1, the spline 14 includes a pair of opposing surfaces 14a facing each other, and an outer end surface 14b connecting the opposing surfaces 14a. The back surface 14a is defined by an involute curve, but is not limited to this.

As can be understood from FIG. 1, in the intermediate molded body 8 serving as the gear component 1, there is a toothless region 16 where no spline 14 is formed. That is, there is no spline corresponding to the first position which is the reference position indicated by the arrow M1 in FIG.
The spline corresponding to the second does not exist and is defined as the toothless region 16, the spline corresponding to the 24th indicated by the arrow M3 does not exist and is defined as the toothless region 16, and the spline corresponding to the 35th indicated by the arrow M4 is defined. Is missing and tooth missing region 16
It has been.

In this gear part 1, the missing tooth region 1
6 is used in the following manner, for example. That is, an appropriate number of oil holes penetrating in the thickness direction are formed in the toothless region 16. When the gear component 1 is used, hydraulic fluid flows in through the oil hole due to the generated centrifugal force. It is preferable that there is no spline in the formation of the oil hole. However, the missing tooth region 16
Is not limited to this.

In FIG. 1, the target dimensions in the vicinity of the spline 14 are as follows. The thickness A of the spline 14 in the circumferential direction near the tooth bottom of the spline 14 is 4.81 mm,
6, the interval B between the tooth roots in the circumferential direction is 8.03 mm,
The outer diameter C is 96 mm, and the inner diameter E is 83.7 mm. Next, the main part of the forging device used in this embodiment will be described with reference to FIG. In FIG. 3, the die 2 is provided with a die hole 20 in the center area thereof, and defines and restricts the outer peripheral portion of the coarse material 7. The die hole 20 has a ring-shaped enlarged concave portion 22 on the upper surface opening side. This enlarged-diameter concave portion 22 has a ring-shaped tapered surface 22e, a ring-shaped vertical wall surface 22f, and a ring-shaped bottom surface 22k. Have been. Further, a ring-shaped holder 33 is disposed on the lower bolster side of the forging device (not shown), and the die 2 is fitted and held in the holder 33. The die 2 is fixed to the upper surface side of the pressure-resistant plate 30 by attaching the ring-shaped holding plate 34 to the holder 33 with bolts 35.

The mandrel 4 has a substantially cylindrical shape, is disposed substantially coaxially in a die hole 20 of the die 2, and regulates and restrains the inner peripheral portion of the coarse material 7. A ring-shaped gap 44 including the enlarged diameter concave portion 22 is formed between the inner peripheral portion of the die hole 20 of the die 2 and the outer peripheral portion of the mandrel 4. The gap 44 serves as a molding cavity for molding the intermediate molded body 8 to be the gear component 1.

As shown in FIG. 3, the mandrel 4 and the die 2
And a knockout sleeve 50 for releasing, a knockout pin 5 for pushing up the knockout sleeve 50.
2 are arranged. Knockout pin 52 passes through pin passage 57 formed in mandrel 4. Further, a substantially cylindrical punch 55 functioning as a pressing die is held on the upper voltastatic side of the above-described forging device, which can be raised and lowered, and ring-shaped pressing plates 56 and 57 surrounding the punch 55 are held. Have been. At the tip of the punch 55, a ring-shaped pushing portion 55c that defines the concave portion 55a is formed. As shown in FIG. 3, the concave portion 55a is fitted into the distal end portion 4a of the mandrel 4, thereby performing mutual positioning.

FIG. 4 shows a main part in a state where the mandrel 4 is inserted into the die hole 20 of the die 2. As can be understood from FIG. 4, a group of molding grooves 26 is formed in the inner peripheral portion of the die hole 20 of the die 2 described above. The forming groove group 26 is formed in the inner peripheral portion of the die hole 20 in a circumferential direction, that is, an arrow R1.
Formed grooves 2 formed at predetermined intervals along the direction
Consists of seven. The forming groove 27 is formed by the spline 14 described above.
And extends in the axial direction of the die 2, that is, in a direction parallel to the direction of the arrow P1. The molding groove 27 is
A pair of mold surfaces 27a facing each other, and a pair of mold surfaces 27a
And a mold surface 27b connecting the two.

6 to 8 show the mandrel 4. FIG. FIG.
FIG. 9 is a sectional view taken along line W3-W4-W5 of FIG. FIG.
FIG. 7 is a diagram viewed from the direction of arrow W1 in FIG. 6. FIG. 8 is a diagram viewed from the direction of arrow W2 in FIG. As shown in FIG. 7, a total of four escape grooves 47 are formed at predetermined intervals along the circumferential direction in the outer peripheral portion 4x of the mandrel 4. As shown in FIG. 6, the escape groove 47 extends along the axial direction of the mandrel 4.

As can be further understood from a comparison between FIGS. 1 and 4, the relief groove 47 is located so as to face the toothless region 16.
It is arranged between two formed groove grooves 27 adjacent to each other in the circumferential direction, that is, in the direction of arrow R1. As can be understood from FIG. 4, the escape groove 47 is formed by a pair of groove side faces 47 facing each other.
a, 47b, and a groove bottom surface 47c connecting the pair of groove side surfaces 47a, 47b. As shown in FIG.
The direction of the depression is the shape of the groove 27 formed in the die 2.
Is opposite to the direction of the depression.

FIG. 9 shows a cross section of a main part of the cylindrical rough shaped material 7. The rough material 7 is obtained by hot forging a steel material (for example, S45C) into a predetermined rough land shape by hot forging. The coarse material 7 includes a rough cylindrical body 70 and a rough cylindrical body 7.
0 and a coarse flange portion 71 extending in the centrifugal direction integrally.
And a large-diameter, large-diameter cylindrical body 72 extending in the axial direction from the rough flange portion 71. The rough cylindrical body 70 corresponds to the cylindrical body 10 of the gear component 1. The rough flange portion 71 corresponds to the flange portion 11 of the gear component 1, and has a shape similar to the flange portion 11 of the gear component 1.
Has dimensions. The large-diameter large-diameter cylindrical body 72 corresponds to the large-diameter cylindrical body 12 of the gear component 1 and has a shape and dimensions similar to those of the large-diameter cylindrical body 12 of the gear component 1.

In FIG. 9, according to the rough material 7, the inner diameter Da of the rough cylindrical body 70 is 83.8 mm, the outer diameter Db of the rough cylindrical body 70 is 100.2 mm, and the coarse cylindrical body 72 is large. Inner diameter D
c is 108 mm, and the outer diameter Dd of the large-diameter large cylindrical body 72 is 11
8 mm is a target value. The inside diameter and outside diameter mean the diameter. In FIG. 9, in the present embodiment, the large inner diameter D4 of the portion corresponding to the valley of the forming groove 27 of the die 2 is a value close to the outer diameter Db of the coarse material 7, that is, 99.78.
5 mm. The target value of the inner diameter D5 of the portion corresponding to the peak of the formed groove 27 is 95.786 mm.
The target value of the inner diameter D3 of the vertical surface 22t of the enlarged diameter concave portion 22 is 118 mm. The outer diameter D6 of the mandrel 4 is a value approximating the inner diameter Da of the coarse material 7 and is 83.7 mm.
It has been.

In the pressing step of this embodiment, as shown in FIG. 9, the inner peripheral portion of the die hole 20 of the die 2 and the mandrel 4 are formed.
The rough cylindrical member 70 of the cylindrical rough member 7 faces the ring-shaped gap 44 between the outer peripheral portion of the cylindrical member and the cylindrical member 70. In this state, the forging device (not shown) is driven to lower the punch 55 in the direction of arrow Y1 as shown in FIG. Then, the rough material 7 is strongly pressed by the pressing portion 55c of the punch 55, and the rough material 7 is forcibly pushed into the gap 44 between the die 2 and the mandrel 4. In addition, this indenting process is performed for the rough material 7
Is performed in a cold state, which is a normal temperature state.

In the pushing step, the material of the rough cylindrical body 70 of the rough material 7 is mainly
The air flows into the space defined by the arrow 7 in the direction of the arrow N1 (see FIG. 10). As a result, a large number of splines 14 are formed on the outer peripheral portion of the crude material 7 by the mold surfaces 27a and 27b of the forming groove 27. The spline 14 has a shape substantially similar to the shape of the groove 27 and extends in the axial direction, that is, the direction parallel to the direction of the arrow P1 (see FIG. 1).

In the present embodiment, since the spline 14 is not formed in the toothless region 16, the material portion of the coarse material 7 corresponding to the toothless region 16 becomes extra as described above, and is essentially a destination. There is no one. Therefore, the extra material due to the toothless region 16 is provided in the direction of the arrow N2 (FIG. 10) in the escape grooves 47 (four in this embodiment) of the mandrel 4.
See). As a result, a surplus relief projection 80 as shown in FIGS. 1 and 2 is formed. Accordingly, the ring-shaped intermediate molded body 8 having the extra thickness relief projections 80 (a total of four) in addition to the splines 14 is formed.

As shown in FIG. 2, in the circumferential direction, that is, in the direction of arrow R1, the extra thickness relief projection 80 and the missing tooth region 16 are substantially in phase. FIG. 5 shows an enlarged view of the vicinity of the excess flesh relief projection 80. In FIG. 5, imaginary lines T1 and T2 extend in the radial direction of the intermediate molded body 8, and virtually connect the roots of the end faces 80h and 80i in the circumferential direction of the extra thickness relief projection 80 to the center axis of the intermediate molded body 8. Line. As shown in FIG.
One end face 80h in the circumferential direction of the escape projection 80 (in other words, the groove side surface 47a of the escape groove 47) is located inside the imaginary line T1 by an angle α. Further, the other end face 80i (from another viewpoint, the groove side face 47 of the escape groove 47)
Similarly, b) is located inside the imaginary line T2 by an angle β (α = β).

In this embodiment, SA is the cross-sectional area of the excess thickness relief projection 80 (that is, the cross-sectional area of the escape groove 47), and the cross-sectional area of the spline 14 (that is, the cross-sectional area of the forming groove 27).
Is SB, it is preferable that the relationship between them is SB ≦ SA in order to avoid burrs. After the formation of the intermediate molded body 8 as described above, the punch 55 is then moved to the arrow Y2.
In the direction to release from the die 2 and push up the knockout pin 52 to push the knockout sleeve 5
0 is pushed up, whereby the intermediate molded body 8 is taken out from the die hole 20 of the die 2.

Thereafter, the intermediate molded body 8 is set in a cutting machine in order to perform a removing step. Then, the surplus relief projection 80 of the intermediate molded body 8 is cut by the cutting tool of the cutting machine.
To remove. In this case, a mode in which the entire inner peripheral portion 8i of the intermediate molded body 8 including the excess thickness relief projection 80 is cut and removed by a predetermined depth may be adopted. Alternatively, the extra relief projection 8
A configuration in which only 0 is removed by cutting may be adopted. Thus, the gear component 1 having the spline 14 is formed from the intermediate molded body 8.

(Test Example) In the above-described embodiment, the groove width (the width of a circular arc in the circumferential direction) of the relief groove 47 formed on the outer peripheral portion of the mandrel 4 is L1 (see FIG. 4), and the groove depth is Was set to K1 (see FIG. 4), L1 and K1 were appropriately changed, and the relationship between the two was tested. The test results are shown in FIG.
In FIG. 11, ● indicates that burr was generated due to excess material,
○ means that no burr is generated due to excess thickness.

In the embodiment of the present invention, as shown in FIG. 11, even if the groove depth K1 is large, when the groove width L1 of the escape groove 47 is small, burrs are generated and the "burr-existing region" is formed. It is easy to become an area. Further, even when the groove depth K1 was small, it was confirmed that as the groove width L1 became large, burrs became less likely to occur, and the region shifted to a "burr-free region". However, if the groove width L1 becomes excessively large, the material portion which should flow into the molding groove 27 and originally form the spline 14 may not easily flow into the molding groove 27. In this sense, the groove width L
Making 1 too large is not preferred. Therefore, as shown in FIG. 5, it is preferable to set an interval of ΔL between the end face 80 h of the excess thickness relief projection 80 and the root of the spline 14. When the groove depth K1 becomes excessively large,
Since the material does not sufficiently flow into the escape groove 47, it is not preferable to make the groove depth K1 excessively large.

From such test results, it is presumed that in the form of the spline 14 according to the present embodiment, the groove width L1 of the escape groove 47 is preferably about 6 mm and the groove depth K1 is preferably about 2 mm. (Other Examples) In the above-described example, the spline 14 is formed on the outer peripheral portion of the intermediate molded body 8 and the excess-thickness relief projection 80 is formed on the inner peripheral portion 8i of the intermediate molded body 8, but is not limited thereto. Instead, the opposite form may be used. In other words, the spline may be formed on the inner peripheral portion 8i of the intermediate molded body 8 serving as the gear component 1, and the extra thickness relief projection may be formed on the outer peripheral portion of the intermediate molded body 8. In this case, the forming groove for forming the spline is formed on the outer peripheral portion 4x of the mandrel 4, and the escape groove having the same phase as the toothless region in the circumferential direction is formed on the inner peripheral portion of the die hole 20 of the die 2. You.

In the above-described embodiment, the number of missing tooth regions 16 is four, but is not limited thereto, and may be smaller or larger. In the above-described embodiment, the tooth-shaped ridge is applied to the molding of the spline 14, but may be applied to a shape other than the spline. For example, a form in which the teeth are applied to gear teeth extending in the axial direction may be used.

It is needless to say that the dimensional relationship is not limited to the above, and can be changed as needed. The above-described example is an example applied to forging, but is not limited to this, and may be applied to an extrusion molding apparatus that forms a spline by extruding a rough material using an extrusion die and a mandrel. it can.

The present invention is not limited to the embodiment described above and shown in the drawings, but can be appropriately selected as needed without departing from the scope of the invention.

[0035]

According to the method of the present invention, the material portion of the coarse material corresponding to the missing tooth region naturally has an excess thickness, but the excess material portion corresponds to the missing tooth region. It flows into the relief groove formed at the position. Therefore, it is advantageous in reducing or avoiding that the material portion which becomes the excess becomes burrs. Therefore, it is advantageous for reducing and avoiding flaws caused by burrs.

[Brief description of the drawings]

FIG. 1 is a perspective view of the vicinity of a projection for releasing a surplus wall of an intermediate molded body serving as a gear component.

FIG. 2 is a bottom view of the intermediate molded body.

FIG. 3 is a longitudinal sectional view of a main part of the forging device.

FIG. 4 is an enlarged perspective view of the vicinity of a relief groove formed on an outer peripheral portion of a mandrel inserted into a die hole of the die.

FIG. 5 is a configuration diagram of a main part of the intermediate molded body.

FIG. 6 is a cross-sectional view of the mandrel along W3-W4-W5 in FIG.

FIG. 7 is a view of FIG. 6 as viewed from the direction of arrow W1.

FIG. 8 is a view of FIG. 6 as viewed from the direction of arrow W2.

FIG. 9 is a cross-sectional view of a state in which a coarse material is positioned above a die.

FIG. 10 is a cross-sectional view showing a state in which a coarse material is pushed into a die hole of a die by a punch.

FIG. 11 is a graph showing the relationship between the groove width and the groove depth of the escape groove in the presence or absence of burrs.

FIG. 12 is a perspective view of a gear component provided with splines showing a partially cut state.

FIG. 13 is a cross-sectional view according to the related art, schematically showing a state in which a coarse material is pressed into a die hole of a die by a punch.

FIG. 14 is a configuration diagram according to the prior art, schematically showing a rough material having burrs generated when the rough material is pushed into a die hole of a die.

[Explanation of symbols]

In the figure, 1 is a gear part (metal molded product), 14 is a spline (toothed ridge), 16 is a toothless region, 2 is a die, 26 is a group of forming grooves, 27 is a forming groove, 4 is a mandrel, 47 is an escape groove, 55 is a punch, 7 is a coarse material, 8 is an intermediate molded body, 80
Indicates a protrusion for releasing excess meat.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B21K 1/30 B21J 5/06 B21J 5/12

Claims (1)

(57) [Claims] 1. One of an inner peripheral portion and an outer peripheral portion has a plurality of toothed ridges arranged at intervals in a circumferential direction and extending in parallel with an axial direction, and the teeth are provided at predetermined positions in the circumferential direction. A method for obtaining a metal molded product having a toothless region in which a ridge is not present, comprising: a metal-made rough shaped member having a cylindrical shape; a die having a die hole and defining an outer peripheral portion of the rough-shaped material; A mandrel arranged substantially coaxially in a die hole of the die to define an inner peripheral portion of the coarse material; and a mandrel formed on one of an inner peripheral portion of the die hole and an outer peripheral portion of the mandrel, and an axial length direction. A forming groove group formed by a plurality of forming grooves extending in a parallel direction and forming the tooth-shaped ridge on the metal molded product; and formed on the other of the inner peripheral portion of the die hole and the outer peripheral portion of the mandrel. Is located between the forming grooves adjacent to each other in the circumferential direction and the toothless region in the circumferential direction. Between the inner peripheral portion of the die hole of the die and the outer peripheral portion of the mandrel using a relief groove provided in a corresponding phase and concave in a direction opposite to the concave direction of the forming groove group in the radial direction. Into the ring-shaped gap, strongly press the cylindrical coarse material by a punch and push it in. With the forming groove group, one of the outer peripheral portion and the inner peripheral portion of the coarse material is parallel to the axial direction. Forming a plurality of tooth-shaped ridges extending in the direction, and flowing a material portion of the coarsely shaped material corresponding to the missing tooth region into an escape groove to form an intermediate molded body having a surplus relief projection. A step of cutting and removing the surplus relief projection of the intermediate molded body taken out of the die to obtain a metal molded product. Molding method for metal molded products with ridges.