JPH1130310A - Sintering internal gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve rigidity in respective parts by reducing a roughness and compactness difference at the time of compression, to improve fitting position accuracy in an internal gear part. SOLUTION: A root part 29 of a helical gear 27, to be formed on the thrust directional one end edge 25 of an outer side cylindrical body 12, is extended toward an inner diameter direction, and is connected to the outer peripheral end part gear side disk surface 30 of a flange part 26 by an inner side taper-like part 31 tilted by a given angle to the flange part gear side disk surface 30 extending direction. An outer side taper-like part 33 is positioned, between the addendum circle part 28 of the helical gear 27 and the outer peripheral surface 24a of the outer side cylindrical body 24, in a diameter direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to weight, moldability,
The present invention relates to a sintered internal gear for improving the balance between cost and strength and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventional internal gears of this type include, for example, a flange portion and a helical gear portion used in a planetary gear device of an automatic transmission described in Japanese Patent Application Laid-Open No. 5-58178. Are formed separately and are combined with each other.

As shown in FIG. 7, an internal gear 1 in which such a flange portion and a helical gear portion are integrally formed by sinter molding is a planetary gear provided in an automatic transmission 2 of a vehicle. Used for the gear device 3.

In such a structure, the sintered internal gear 1 made of a sintered metal is connected to a substantially cylindrical outer cylinder 4 and one end 5 of the outer cylinder 4 in the thrust direction. The flange 6 is mainly composed of a substantially disk-shaped flange 6 and a boss 7 formed substantially at the center of the flange 6.

[0005] Of these, the outer cylinder 4 has an inner peripheral surface portion 8.
A helical gear 9 is formed as an internal gear.

The flange 6 has a tapered shape that is inclined at a predetermined gradient from the boss 7 to the outer diameter 8 of the flange 6.

The sintered internal gear 1 is manufactured through the steps shown in FIG.

That is, a sintered metal raw material (iron powder or other metal powder and a lubricant) as shown in FIG. 1A is mixed at a predetermined ratio by a mixer 11 as shown in FIG. After mixing and mixing, the mold 12 is filled with a constant weight as shown in FIG.

Then, each upper punch 12a and the like of the mold 12 and each lower punch 12b and the like are slid along the core rod 13 so as to be 3 to 7 tonf / m from the vertical direction.
Compression molding is performed by applying a pressure of square cm.

Next, the compacted powder compact 15 is
As shown in (d) in the figure, the metal particles are heated in a sintering furnace 14 at a high temperature below the melting point for a certain period of time, so that diffusion bonding of metal particles progresses and alloys.

[0011] Then, in order to further improve the quality and characteristics and obtain a finished product according to the purpose of use and application, post-processing is performed. In this sintered internal gear 1, the alloyed powder compact 15 is placed in a mold 16 as shown in FIG. Sizing is performed by sliding the mold 16b and the like along the core rod 13 and applying pressure again from above and below.

After sizing, an inspection is performed as shown in FIG.
Is obtained ((g) in the figure).

In the sintered internal gear 1 configured as described above, as shown in FIG. 9, the flange portion 6 is formed so as to exhibit the tapered shape, so that the boss portion 5 is formed.
In the vicinity, the outer peripheral end portion 10 close to the helical gear 9 is reduced in weight over a wide area while improving the thick-walled rigidity.

[0014]

However, in such a device, in order to reduce the weight, as shown by a two-dot chain line in FIG. If a tapered shape inclined at a predetermined gradient is provided, the thickness of the outer end edge 17a of the boss concave portion 17 for supporting the thrust bearing in the thrust direction in the thrust direction one end 5 is particularly thin.

For this reason, the supporting rigidity of the outer cylindrical body 4 at the mounting base end position is insufficient, the flange 6 is distorted, and the helical gear 9 opens so-called flowers at the time of the die cutting or sizing, so that the helical gear 9 is mounted. There is a possibility that the position accuracy and the gear accuracy may be impaired.

Further, adjacent to such a thin portion, the root 9a of the helical gear 9 has a thick portion requiring a large amount of sintered metal material in the thrust direction. Therefore, the density changes drastically, and the crack 18
Was the cause of the occurrence.

Further, a difference in density occurs at one end in the thrust direction connecting the outer cylindrical body 4 adjacent to the base 9a of the helical gear 9, and a crack 19 is generated at the time of die-cutting or sizing. There was a fear.

Further, since a large amount of sintered metal material is required in the thrust direction also at the tip of the helical gear 9 in the tip circle,
It became further rough, and it was difficult to give a predetermined hardness to the tip circle portion of the helical gear 9.

In particular, as shown by a solid line in FIG.
Even if a taper is formed to the extent that chamfering R20 is performed on the 0, if the upper end surface 21 of the outer peripheral end portion 10 has a planar shape, it is difficult to obtain a predetermined hardness, and it is desired to obtain a predetermined hardness. When the molding pressure of the upper and lower punches 12a and 12b is increased, there is a problem that the life of the mold 12 itself is shortened.

Therefore, the present invention provides a sintered interface that can improve the rigidity of each part by reducing the difference in density during compression, thereby improving the mounting position accuracy of the internal gear portion and the internal gear accuracy. It is an object to provide a null gear.

[0021]

According to the first aspect of the present invention, an internal gear portion is formed inside a substantially cylindrical outer cylindrical body, and a thrust of the outer cylindrical body is formed. At one end in the direction, a substantially internal disc-shaped flange is integrally connected to the sintered internal gear, and the root of the internal gear formed at one end in the thrust direction of the outer cylinder is moved in the radial direction. A sintered internal gear that extends toward the outer peripheral end of the flange portion and is connected to the outer peripheral gear side plate surface by an inner tapered portion inclined at a predetermined angle with respect to the direction in which the flange portion gear side panel surface extends. .

For example, the predetermined angle of the inner tapered portion is 45 degrees with respect to the direction in which the flange portion gear side plate surface extends.
It is configured to exhibit {± 15}.

[0023] According to the first aspect of the present invention, the root portion of the internal gear formed at one end in the thrust direction of the outer cylindrical body extends in the inner diameter direction and the flange portion. The outer peripheral end of the flange portion is smoothly connected to the gear-side board surface by an inner tapered portion inclined at a predetermined angle with respect to the gear-side board surface extending direction. At the same time, the thickness in the thrust direction is increased, the rigidity of the root of the internal gear is improved, and the occurrence of cracks is suppressed.

According to the second aspect of the present invention, the internal gear portion is formed inside the substantially cylindrical outer cylindrical body, and a substantially disk-shaped one end edge of the outer cylindrical body in the thrust direction. A sintered internal gear in which a flange portion is integrally connected, wherein a radially extending portion of the internal gear is provided at an outer end of a connection portion between one end in a thrust direction of the outer cylindrical body and an outer peripheral end of the flange portion. It is characterized by a sintered internal gear in which an outer tapered portion is formed between a tip circle of the portion and an outer peripheral circle of the outer cylindrical body.

According to the second aspect of the present invention, the outer tapered portion is formed at an outer end of a connecting portion between one end of the outer cylindrical body in the thrust direction and the outer peripheral end of the flange. Since it is located between the addendum circle of the internal gear portion in the radial direction and the outer peripheral circle of the outer cylindrical body, an enlarged area obtained by the inclination of the outer tapered portion corresponds to one of the molds. ,
By increasing the contact area with the sintered metal raw material and improving the pressing area, it is possible to increase the density of the mounting portion of the outer tubular body and increase the predetermined rigidity without increasing the molding pressure.

Therefore, cracks can be prevented from occurring, and the durability of the molding die can be improved.

According to the third aspect,
A sintered internal gear in which an internal gear portion is formed inside a substantially cylindrical outer cylinder, and a substantially disc-shaped flange is integrally connected to one end of the outer cylinder in a thrust direction. The connection between the one end edge in the thrust direction of the outer cylindrical body and the outer peripheral end of the flange portion is substantially orthogonal to a perpendicular line dropped from the center in the thrust direction of the internal gear portion to the outer end portion. It is characterized by a sintered internal gear in which an outer tapered portion having an angle is formed.

Here, the substantially orthogonal angle is specifically about 90 ° ± 15 °.

According to a third aspect of the present invention, an outer tapered portion formed at an outer end of a connection portion between one end in the thrust direction of the outer cylindrical body and the outer peripheral end of the flange portion is provided. Since it has an angle that is substantially perpendicular to a perpendicular line that is lowered from the center in the thrust direction of the internal gear portion to the outer end portion, the sintered metal material is directed toward the tip of the internal gear portion during compression molding. Is pressed and filled.

[0030] For this reason, since the sintered metal material is sufficiently filled in the tooth tip portion and the base portion of the internal gear portion, a predetermined rigidity can be secured without generating a rough portion.

Further, since the outer tapered portion is formed, the outer peripheral end of the flange portion is robbed, the weight can be reduced over a wide range, and the inertia ratio can be improved.

[0032] According to the fourth aspect of the present invention, a flat step formed substantially parallel to the gear-side board surface of the flange portion is provided adjacent to the tapered portion. 2. A sintered internal gear according to item 2 or 3.

According to the fourth aspect of the present invention, a flat step portion is formed substantially parallel to the gear-side plate surface of the flange portion adjacent to the tapered portion.

For this reason, for example, even when the thrust bearing supporting boss concave portion is formed in the flange portion, the thickness of the boss concave portion edge in the thrust direction is suppressed from becoming thinner, and the adjacent tapered portion is formed. The difference in density from the part is alleviated.

Further, according to the fifth aspect, the step portion includes a first step portion extending in a radial direction from a boss formed substantially at the center of the flange portion, and a first step portion extending in the radial direction. A second step portion formed between the addendum circle of the internal gear portion and the outer peripheral circle of the outer cylindrical body; and at least one of the first and second step portions. One of the features is a sintered internal gear according to claim 4, wherein a positioning punch hole is formed.

[0036] According to the fifth aspect of the present invention, the step portion includes a first step portion extending in a radial direction from a boss formed substantially at the center of the flange portion, A second stepped portion formed to be located between the addendum circle of the internal gear portion and the outer peripheral circle of the outer cylindrical body in the direction, and the taper formed in the flange portion is stepped. Because of the shape, the thickness of each part in the thrust direction can be made substantially uniform.
For this reason, in the radial direction of the flange portion, the compression ratio of the sintered metal raw material in the adjacent portion is also substantially uniform, and the difference in density is reduced.

In addition, since the positioning punch hole is formed in at least one of the first and second step portions, the positioning punch hole is substantially perpendicular to the outer surface of the flange portion. Can be formed. For this reason, it is possible to smoothly remove and size the mold without unnecessarily catching when removing it from the molding die, thereby suppressing an increase in the molding process and preventing a decrease in gear accuracy due to flowering or the like.

[0038]

Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. The same or equivalent parts as those in the conventional example are denoted by the same reference numerals and described.

FIGS. 1 to 5 show Embodiment 1 of the present invention.
1 shows a sintered internal gear and a method of manufacturing the same.

First, the structure of the sintered internal gear 23 of the first embodiment will be described. The sintered internal gear 23 made of sintered metal is mainly composed of a substantially cylindrical outer cylindrical body 24. , One end edge 2 of the outer cylinder 24 in the thrust direction
5, a flange portion 26 having a substantially disk shape,
The boss portion 7 is formed substantially at the center of the flange portion 26.

The outer cylindrical body 24 includes the inner peripheral surface 8.
A helical gear 27 is formed as an internal gear.

The root 2 of the helical gear 27 formed at one end 25 of the outer cylinder 24 in the thrust direction.
9 is connected to the outer peripheral end gear side plate surface 30 of the flange portion 26 by an inner tapered portion 31 extending in the inner diameter direction and inclined at a predetermined angle with respect to the extending direction of the flange portion gear side plate surface 30. Have been.

In the first embodiment, as shown in FIG. 3, the predetermined angle θ of the inner tapered portion 31 is θ = 45 ° ± 15 ° with respect to the extending direction a of the flange portion gear side board surface 30.゜.

Further, a radially extending tooth tip circle 28 of the helical gear 27 is formed on an outer end 32 of a connecting portion between the one end edge 25 of the outer cylinder 24 in the thrust direction and the outer peripheral end 26a of the flange. Outer peripheral surface 2 which is the outer peripheral circle of outer cylinder 24
4a (between C-C) and the outer tapered portion 33
Are formed.

As shown in FIG. 2, the outer tapered portion 33 is connected to one end 25 of the outer cylindrical body 24 in the thrust direction.
Outer end 32 of connection portion with outer peripheral end 26a of flange portion
The helical gear 27 is formed so as to have an angle α substantially perpendicular to a perpendicular L to the edge 34 from the center portion 27a (L1 = L2) in the thrust direction of the helical gear 27 with respect to the edge 34.

Here, the substantially orthogonal angle α is, specifically, about α = 90 ° ± α1 (α1 is within 15 °).

In the first embodiment, a flat step portion 35 is provided adjacent to the outer tapered portion 33 so as to be substantially parallel to the gear-side board surface 30 of the flange portion 26. .

The first step is connected to the stepped portion 35 from the boss 7 formed substantially at the center of the flange portion 26 and to the tapered portion 36 having a gentle inclination and extending in the radial direction. A part 37 is provided.

Further, the step 35 is provided with the first step 3
7 through a slightly steeply inclined central tapered portion 38, and radially between an addendum portion 28 of the helical gear 27 and an outer peripheral surface 24a of the outer cylindrical body 24 (C-
C), a second step portion 39 is formed to be located at a position between the first step portions 37 and the second step portions 39.
Are formed so as to have a two-step shape.

The first step 37 has a predetermined depth so that the positioning punch hole 40 is perpendicular to the flat portion of the outer surface of the first step 37 along the thrust direction. And has a circular shape.

Next, the configuration of a molding die for compression-molding the sintered metal material forming the sintered internal gear 23 and a sizing die used for sizing are shown in FIG.
This will be described with reference to FIG.

As shown in FIG. 4, a molding die used for compression molding according to the first embodiment is provided at a position where a shaft is provided, and a spline portion 7a is formed inside the shaft hole of the boss portion 7. A substantially cylindrical core rod 101 is provided.

A die 102 in which an annular molding space 102a for accommodating the sintered metal material is formed substantially at the center of the core rod 101 is arranged in advance.

The core rod 101 and the die 102
Between the first to fourth annular lower punch members 103 to 106
Are arranged.

Of these, the first and fourth lower punch members 10
3 and 106 are configured to be able to slide upward when the mold is clamped.

The first to fourth lower punch members 1
A first upper punch member that clamps the mold by sliding down along the thrust direction from above in opposition to the first to fourth lower punch members 103 to 106 at positions above 03 to 106. 107 is provided.

In FIG. 4, for the sake of explanation, the raw material filling state is shown on the left side of the center line h, and the compressed state is shown on the right side of the center line h.

As shown in FIG. 5, the sizing die used for sizing according to the first embodiment is provided at a shaft disposition position and inserted into a spline portion 7a inside the shaft hole of the boss portion 7. A substantially cylindrical core rod 109 is provided.

A die 110 in which an annular molding space 110a for accommodating the sintered internal gear 23 is formed substantially at the center of the core rod 109 is arranged in advance.

The core rod 109 and the die 110
Between them, annular first to third lower punch members 111 to 113 are provided.
Are arranged.

The first lower punch member 111 includes:
It is configured to be able to slide upward when the mold is opened.

The first to third lower punch members 1
The first upper punch member 114 that performs sizing by sliding down along the thrust direction from above in opposition to the first to third lower punch members 111 to 113 at positions above the first to third lower punch members 114 to 113. Is provided.

In FIG. 5, for simplicity, the sizing compression state is shown on the left side of the center line h, and the mold opening state is shown on the right side of the center line h.

Next, the operation of the first embodiment will be described.

First, through substantially the same steps as those shown in FIG. 8, the sintered internal 23 of the first embodiment is manufactured.

That is, a sintered metal raw material (iron powder or other metal powder and a lubricant) as shown in FIG. After mixing and mixing, the mold 12 is filled with a constant weight as shown in FIG.

That is, as shown on the left side of the center line h in FIG. 4, with the first upper punch member 107 retracted upward, the sintered metal raw material is flush with the upper surface of the die 102. Fill.

Then, as shown in FIG. 4, each upper punch member 107 of the molding die and each lower punch member 103
And 106 are slid along the core rod 13 to apply a pressure of 3 to 7 tonf / cm 2 from above and below to perform compression molding.

At this time, as shown on the right side of the center line h in FIG. 4, the first upper punch member 107 is slid down along the thrust direction from above at substantially the same time as the first and second punch members 107.
The fourth lower punch members 103 and 106 are raised to perform mold clamping.

At the time of the mold clamping, as shown in FIG. 3, the root portion 29 of the helical gear 27 formed at one end 25 in the thrust direction of the outer cylindrical body 24 extends in the inner diameter direction to form the flange portion. The outer peripheral end of the flange portion 26 is smoothly connected to the gear-side board surface 30 by an inner tapered portion 31 inclined at a predetermined angle with respect to the direction in which the gear-side board surface 30 extends. The difference in density between the root portion 29 of the helical gear 27 adjacent in the direction and the connection portion of the outer cylindrical body 24 in the thrust direction one end 25 is reduced, and the thickness in the thrust direction is increased, so that the helical gear 27
The rigidity of the base portion 29 is improved, and the occurrence of cracks is suppressed.

Further, an outer tapered portion 33 is provided radially on the outer end 32 of the connecting portion between the one end 25 of the outer cylindrical body 24 in the thrust direction and the outer peripheral end 26a of the flange. And the outer cylindrical body 2
4 (between C and C)
The contact area between the upper first punch member 107 and the sintered metal raw material is increased by the enlarged area obtained by the inclination of the outer tapered portion 33, and the pressing area is increased to increase the molding pressure. Without increasing the compressive force, the density of the mounting portion of the flange portion 26 of the outer cylindrical body 24 is increased, and the predetermined rigidity can be secured.

Accordingly, the occurrence of cracks can be prevented, and the durability of the molding die can be improved.

The outer tapered portion 33 formed at the outer end 32 of the outer cylindrical body 24 at one end 25 in the thrust direction of the outer cylindrical body 24 and the outer peripheral end 26a of the flange is formed in the thrust direction of the helical gear 27 in the thrust direction. Since it has an angle substantially perpendicular to the perpendicular L dropped from the central portion 27a to the edge 34, the tip circle portion 2 of the helical gear 27 during compression molding.
The sintered metal raw material is pressed in eight directions,
The tip portion 28 and the root portion 29 of the helical gear 27, which flow in eight directions and tend to be a rough portion in the past, are filled.

Further, in the first embodiment, the first
The lower punch member 103 rises from below and further compresses the outer cylindrical body 24 so as to be dense.

For this reason, the tip portion 2 of the helical gear 27
Since the sintered metal material is sufficiently filled in the base 8 and the base portion 29, a predetermined rigidity can be secured without generating a rough portion.

Further, since the outer tapered portion 33 is formed, the outer peripheral end of the flange portion 26 is robbed,
The weight can be reduced over a wide range, and the inertia rate can be improved.

A flat step 35 is formed adjacent to the outer tapered portion 33 so as to be substantially parallel to the gear side board surface 30 of the flange 26.

For this reason, as shown in FIG. 2, for example, the first step portion 37 of the step portion 35 is formed so as to be substantially parallel to the gear-side platen surface 30, so that the thrust Even if the bearing supporting boss recess 17 is formed,
In the boss concave portion 17 end edge 17a, the degree to which the thickness in the thrust direction becomes thin is suppressed, and the difference in density between the adjacent central tapered portion 38 is reduced.

The second step 39 of the step 35 is
Since the base portion 29 is formed so as to be substantially parallel to the gear-side platen surface 30, the thickness of the root portion 29 in the thrust direction in the thin direction is suppressed, and the difference in density between adjacent outer tapered portions 33 is reduced. Be relaxed.

As described above, in the first embodiment, the step 35 extends radially from the boss 7 formed substantially at the center of the flange 26 via the inner tapered portion 36. The first helical gear 2 in the radial direction.
7 and the outer peripheral circle 24 a of the outer cylindrical body 24.
And the second step portion 39 formed so as to be located between (C-C), and the taper formed in the flange portion 26 has a two-stepped shape. The thickness in the thrust direction can be made substantially uniform. For this reason, in the radial direction of the flange portion 26, the compression ratio of the sintered metal raw material in the adjacent portion is also substantially uniform, and the difference in density is reduced.

Then, the sintered internal gear 23 integrally formed by compression molding is provided with the upper and lower punch members 103.
When the first upper punch member 107 is pulled out from the molding die composed of the components 107 to 107, the first lower punch member 103 and the second lower punch member 104 are Pulled out individually. The second lower punch member 104 is pulled out while rotating to form the helical gear portion 7a.

Further, the third lower punch member 105 and the fourth lower punch member 106 are individually pulled out.

At the time of this die-cutting, the supporting rigidity of the joint portion of the flange portion 26 of the outer cylindrical body 24 is improved by making the thickness in the thrust direction substantially uniform at each portion. There is no fear that the mounting position accuracy of the 27 is impaired.

Next, the compacted powder compact is shown in FIG.
As shown in the middle (d), the metal particles are heated in the sintering furnace 14 at a high temperature equal to or lower than the melting point for a certain period of time, so that diffusion bonding of the metal particles proceeds and alloys.

After the baking process, if the dimensional accuracy is insufficient, in order to further improve the quality and characteristics and obtain a finished product according to the purpose of use and use, the sintered body is A so-called sizing process in which the material is pressed into a sizing die, recompressed, and the dimensions are corrected is performed in a post-processing process of the internal gear manufacturing process.

In the sintered internal gear 23 of the first embodiment, the alloyed powder compact is put into a sizing mold and the upper punch of the sizing mold is placed as shown in FIG. Member 114 and each lower punch member 111
To 113 and the like are slid along the core rod 109 and pressure is applied again from above and below to perform sizing.

In the first embodiment, the positioning punch holes 40 formed in the flat first step portion 37 which hardly affect the density are formed in a substantially vertical direction with respect to the outer surface of the flange portion 26. Since it is formed, when the molding die shown in FIG. 4 is extracted from the first upper punch member 107, it can be smoothly removed from the mold without causing unnecessary catching and the like, and the second mold shown in FIG. 1 upper punch member 1
14, when it is adapted to perform the positioning in the rotation direction, the positioning can be performed smoothly, so that the sizing can be easily performed, the increase in the molding process can be suppressed, and the improper mounting at the time of sizing is prevented, and the flower blooms. This can prevent the gear accuracy from deteriorating.

In the first embodiment, the first step portion 37 can secure the thickness in the thrust direction.
The boss recess 17 for supporting the thrust bearing can be of a full circumference type. For this reason, the difference in density is reduced even in the circumferential direction, and the occurrence of cracks can be further suppressed.

After sizing, an inspection is performed as shown in FIG. 8F, and a sintered internal gear 23 as a finished product is obtained (FIG. 8G).

[0090]

Second Embodiment FIG. 6 shows a sintered internal gear 123 according to a second embodiment of the present invention. The same or equivalent parts as those in the first embodiment will be described with the same reference numerals.

In the sintered internal gear 123 of the second embodiment, the outer cylindrical body 24 has one end 2 in the thrust direction.
5, the base portion 129 of the helical gear 127 formed in
An inner tapered portion 31 extending in the inner diameter direction formed in the sintered internal gear 23 of the first embodiment and inclined at a predetermined angle with respect to the extending direction of the flange portion gear side panel surface 30 is provided. , Are not provided.

The structure is substantially the same as the sintered internal gear 23 of the first embodiment, except that the inner tapered portion 31 is not provided.

More specifically, the helical gear 1 is radially attached to the outer end 132 of the outer cylindrical body 24 at the connection end between the one end 25 in the thrust direction and the outer peripheral end 26a of the flange.
An outer tapered portion 133 is formed (located between DD) between the 27 tooth tip circular portion 128 and the outer peripheral surface 24a that is the outer peripheral circle of the outer cylindrical body 24.

As shown in FIG. 6, the outer tapered portion 133 is connected to one end 25 of the outer cylinder 24 in the thrust direction.
Of the helical gear 27 from the central portion 127a in the thrust direction of the helical gear 27 (L3 = L4).
4 is formed so as to exhibit an angle α substantially orthogonal to the perpendicular L lowered to the vertical line 4.

Here, the substantially orthogonal angle α is, specifically, about α = 90 ° ± α2 (α2 is within 15 °).

The step 135 of the second embodiment has a first step 137 and a slightly tapered central tapered portion 3.
8 and is formed so as to be located radially between the tooth tip circular portion 128 of the helical gear 127 and the outer peripheral surface 24a of the outer cylindrical body 24 (between DD). A two-step portion 139 is provided, and each of the first step portions 1 is provided.
37 and the second step portion 139 are formed to have a two-step shape.

Of these, the second step portion 139 is set to be longer in the radial direction than the second step portion 39 of the first embodiment.

In the sintered internal gear 123 of the first embodiment configured as described above, the outer tapered portion 13
The second step portion 139 adjacent to No. 3 is set to be longer in the radial direction than the second step portion 39 of the first embodiment.

For this reason, since the second step portion 139 is formed so as to be substantially parallel to the gear side board surface 30, the thickness of the root portion 129 in the thrust direction in the thrust direction is reduced. The predetermined configuration can be ensured, and the outer tapered portion 133 reduces the difference in density between the adjacent tubular frame 24 that is robbed.

The other structure, operation, and effects are substantially the same as those in the first embodiment, and thus the description thereof is omitted.

Although the first and second embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the first and second embodiments, and the design is within a range not departing from the gist of the present invention. Modifications are included in the present invention.

For example, in the first embodiment, an example in which the outer tapered portion 33 is formed has been described. However, the present invention is not particularly limited thereto. And the like, the helical gear 27 formed at the one end edge 25 of the outer cylinder 24 in the thrust direction.
A base portion 29 of the flange portion 26 extends toward the inner diameter direction and is inclined at a predetermined angle with respect to the extending direction of the flange portion gear side plate surface 30. What is necessary is just to be connected to 30 smoothly.

In the first or second embodiment, the helical gears 27 and 127 are used as the internal gears. However, the present invention is not limited to this, and other types of gears such as a normal spur gear may be used. Is also good.

[0104]

As described above, according to the first aspect of the present invention, the root of the internal gear formed at one end of the outer cylindrical body in the thrust direction is directed toward the inner diameter. The flange portion is smoothly connected to the outer peripheral end gear side plate surface by an inner tapered portion inclined at a predetermined angle with respect to the direction in which the flange portion gear side plate surface extends. In addition to reducing the difference in density between the portions, the thickness in the thrust direction is increased, the rigidity of the root portion of the internal gear is improved, and the occurrence of cracks is suppressed.

According to the second aspect of the present invention, the outer tapered portion is provided at an outer end of a connecting portion between one end of the outer cylindrical body in the thrust direction and the outer peripheral end of the flange.
Since it is located between the addendum circle of the internal gear portion in the radial direction and the outer peripheral circle of the outer cylindrical body, an enlarged area obtained by the inclination of the outer tapered portion corresponds to one of the molds. By increasing the contact area with the sintered metal raw material and improving the pressing area, it is possible to increase the density of the mounting portion of the outer cylindrical body without increasing the molding pressure and to secure a predetermined rigidity.

Accordingly, the occurrence of cracks can be prevented, and the durability of the molding die can be improved.

And, according to the third aspect,
One end of the outer cylindrical body in the thrust direction and an outer tapered portion formed at an outer end of a connection portion between the outer peripheral end of the flange portion and the outer end portion from the center in the thrust direction of the internal gear portion to the outer end. Since it has an angle substantially perpendicular to the perpendicular line to be lowered, the sintered metal material is pressed and filled toward the tip of the internal gear during compression molding.

[0108] For this reason, the tooth tip circle portion and the root portion of the internal gear portion are sufficiently filled with the sintered metal material, so that a predetermined rigidity can be secured without generating a rough portion.

Further, since the outer tapered portion is formed, the outer peripheral edge of the flange portion is robbed, the weight can be reduced over a wide range, and the inertia rate can be improved.

Further, according to the fourth aspect, a flat step portion is formed substantially parallel to the gear-side plate surface of the flange portion adjacent to the tapered portion.

Therefore, for example, even when the boss concave portion for supporting the thrust bearing is formed in the flange portion, the thickness in the thrust direction at the edge of the concave portion of the boss concave portion is suppressed, and the adjacent tapered concave portion is formed. The difference in density from the part is alleviated.

Further, according to the fifth aspect, the step portion has a first step portion extending in the radial direction from a boss portion formed substantially at the center of the flange portion, and a first step portion extending in the radial direction. The taper formed in the flange portion having a second step portion formed so as to be located between the addendum circle of the internal gear portion and the outer peripheral circle of the outer cylindrical body has a stepped shape. Therefore, the thickness of each part in the thrust direction can be made substantially uniform. For this reason, in the radial direction of the flange portion, the compression ratio of the sintered metal raw material in the adjacent portion is also substantially uniform, and the difference in density is reduced.

Further, since the positioning punch hole is formed in at least one of the first and second step portions, the positioning punch hole is substantially perpendicular to the outer surface of the flange portion. Can be formed. For this reason, when extracting from a molding die, it is possible to smoothly remove and size the mold without generating unnecessary catches and the like, and it is possible to suppress an increase in the molding process and to prevent a reduction in gear accuracy due to flowering and the like. It has a practically useful effect.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a sintered internal gear according to a first embodiment of the present invention, taken along a rotation axis.

FIG. 2 is an enlarged cross-sectional view illustrating a configuration of a main part of the sintered internal gear according to the first embodiment.

FIG. 3 is an enlarged cross-sectional view illustrating a configuration of a main part of a sintered internal gear according to the first embodiment and illustrating a root portion of an internal gear.

FIG. 4 is a sectional view showing a molding die of the sintered internal gear according to the first embodiment, in which a raw material filling state is shown on the left side of a center line h, and a compressed state is shown on the right side of the center line h. is there.

FIG. 5 is a cross-sectional view showing a sizing mold of the sintered internal gear according to the first embodiment, in which a sizing compression state is shown on the left side of a center line h, and a mold opening state is shown on the right side of the center line h. It is.

FIG. 6 shows a sintered internal gear according to a second embodiment,
It is an expanded sectional view of an important section.

FIG. 7 is a cross-sectional view for explaining the relationship between an internal gear provided in an automatic transmission or the like of a conventional example and the overall configuration.

FIG. 8 is a schematic view illustrating a manufacturing process of the sintered internal gear.

FIG. 9 is an enlarged cross-sectional view showing a main part of a conventional sintered internal gear.

[Explanation of symbols]

 7 Boss 23,123 Sintered internal gear 24 Outer cylinder 24a Outer peripheral surface (outer circle) 25 One end edge in thrust direction 26 Flange 26a Flange outer peripheral end 27,127 Helical gear (internal gear) 27a, 127a Thrust direction central portion 28,128 Tooth circle portion (tooth circle) 29,129 Root portion 30 Flange portion gear side board surface 32 Connecting portion outer end portion 33,133 Outer tapered portion 34 Edge 35 Step 37,137 No. 1st step 39, 139 2nd step 38 Central taper part Molding die 101 Core rod 102 Die 103 to 106 First to fourth lower punch member 107 First upper punch member Sizing die 109 Core rod 110 Die 111 to 113 First 1-3 Lower punch member 114 First upper punch member

Claims (5)

[Claims] An internal gear portion is formed inside a substantially cylindrical outer cylinder, and a substantially disc-shaped flange is integrally connected to one end of the outer cylinder in a thrust direction. A null gear, wherein a root portion of the internal gear formed at one end in the thrust direction of the outer cylindrical body is extended toward the inner diameter direction, and has a predetermined angle with respect to the direction in which the flange portion gear side panel surface extends. A sintered internal gear which is connected to a gear-side board surface at an outer peripheral end of the flange portion by an inclined inner tapered portion. 2. A sintered interface in which an internal gear portion is formed inside a substantially cylindrical outer cylinder, and a substantially disc-shaped flange is integrally connected to one end of the outer cylinder in a thrust direction. A null gear, a tip end circle of the internal gear portion in a radial direction at an outer end portion of a connection portion between the one end edge in the thrust direction of the outer cylindrical body and the outer peripheral end portion of the flange portion, and the outer cylinder A sintered internal gear having an outer tapered portion located between the outer peripheral circle of the body and the outer tapered portion. 3. A sintered interface in which an internal gear portion is formed inside a substantially cylindrical outer cylinder, and a substantially disc-shaped flange is integrally connected to one end of the outer cylinder in a thrust direction. A null gear, wherein a thrust direction one end edge of the outer cylindrical body and a connection portion outer end portion of the flange portion outer peripheral end portion are lowered from a thrust direction central portion of the internal gear portion to the outer end portion. A sintered internal gear having an outer tapered portion having an angle substantially perpendicular to a perpendicular line to the sintered internal gear. 4. A flat step portion is provided adjacent to the tapered portion and formed substantially parallel to the gear-side panel surface of the flange portion. Sintered internal gear. 5. A step portion extending radially from a boss formed substantially at the center of the flange portion, the step portion comprising:
A second step formed in a radial direction between an addendum circle of the internal gear portion and an outer circumference of the outer cylindrical body; At least one of the
5. The sintered internal gear according to claim 4, wherein a positioning punch hole is formed.