JPH1161203A - Powder compacting device of helical gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a smooth rotation of a rotary punch and to be assembled in a small press machine. SOLUTION: The compacting device 1 is provided with a die 3, which has a compacting part 3a of helical shape formed corresponding to a teeth part of a helical gear on an inner peripheral face, a rotary punch 6b, which is supported rotatable through a thrust bearing 11A and has a helical teeth part 61 engaging with the compacting part 3a on a tip part, and fixed punch 5, which is fixed to a base plate 9. Powder supplied in the die 3 is held with the rotary punch 6b inserted in the die 3 and the fixed punch 5 from both sides and pressurizing the rotary punch 6b by a pressurizing member 7, the powder is compacted, at the same time, the rotary punch 6b is rotated by guiding the helical teeth part 61 of the rotary punch 6b in the circumferential direction with the forming part 3a. In this device, the through bearing 11A is of a sliding bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder molding apparatus for powder molding a helical gear.

[0002]

2. Description of the Related Art As a powder molding apparatus for a helical gear,
For example, there are devices as disclosed in Japanese Patent Publication No. Hei 7-110964 and Japanese Patent No. 2596141, all of which have a structure in which a die is rotated during molding of powder. On the other hand, a device that rotates a punch instead of a die at the time of molding a powder has been widely used, and an example of the structure is shown in FIG.

[0003] This device (1) comprises a cylindrical die (3) having a receiving portion (2) for receiving powder in the center, a die plate (4) fitted to the die (3), and a die ( The lower punch (5) inserted into the receiving portion (2) of 3) from below, the upper punch (6) inserted into the receiving portion (2) from above, and the upper punch (6) downward (to approach the lower punch). The main components are a pressure member (7) for pressing in the direction (1) and a core rod (8) inserted into the accommodating portion (2) of the die (3).

The upper punch (6) includes a first upper punch (6a) on the inner diameter side fixed to the pressing member (7), and a pressing member (7).
And a second upper punch (6b) on the outer diameter side rotatably supported via a pair of thrust bearings (11a). On the other hand, the lower punch (5) is fixed on the base plate (9) at the rest position. The die (3) is rotatably supported on the die plate (4) via a pair of thrust bearings (11b). Conventionally, a rolling bearing having a rolling element such as a roller or a ball is used as the two thrust bearings (11a) and (11b).

[0005] On the inner peripheral surface of the die (3), a formed portion (3a) having a helical shape corresponding to the shape of the tooth formed on the outer peripheral surface of the helical gear is formed. Second upper punch (6
Helical tooth portions (61) and (51) each having a helical shape are formed on the outer peripheral surface from the tip portion to the center portion of b) and the lower punch (5) so as to mesh with the forming portion (3a). .

The compacting by this apparatus is performed in the following procedure. First, the raw material powder is supplied to the container (2) with the lower punch (5) and the core rod (8) inserted into the container (2) of the die (3). Next, the pressing member (7) is pressed and lowered by a ram (not shown), and the upper punch (6a) is pressed.
(6b) is integrally inserted into the inner diameter part of the die (3) to compress the powder in the storage part (2). At this time, the helical teeth (61) of the second upper punch (6b) meshed with the forming part (3a) of the die (3) are guided in the circumferential direction by the forming part (3a). (6b) descends while rotating.
Since the raw material powder rotates in the accommodating portion (2) following the rotation of the upper punches (6a) and (6b), the powder is pressed uniformly to the back side of the helical formed portion (3a). (In the devices described in the above two publications, such an operation is performed by rotating a die), and a helical gear having a complicated shape can be compacted with high precision.

After the molding is completed, when the yoke plate (12) is retracted, the die plate (4) is lowered via the connecting rod (13), and the die (3) is further lowered as the die plate (4) is lowered. Is towed downward. Due to this traction force, the formed portion (3a) of the die (3) is guided in the circumferential direction by the helical teeth (51) of the lower punch (5), so that the die (3) descends while rotating. as a result,
The green compact in the storage part (2) rises relatively to the die (3) and is taken out of the die (3).

[0008] Helical teeth corresponding to the shape of the molded part (3a) are formed on the outer peripheral surface of the green compact taken out from the die (3), and the cross-sectional shape of the core rod (8) is formed in the inner diameter part. Is formed. After putting this green compact in a furnace and sintering, post-processing such as sizing is performed to produce a helical gear.

[0009]

As described above, the thrust bearing 11a) is interposed between the pressing member (7) and the second upper punch (6b). Receives a large thrust load when the powder is compressed. This thrust load is excessive, for example, up to about 5 ton / cm ² per unit area when iron powder is used as the powder. Therefore, if a rolling bearing is used as the thrust bearing (11a) as in the prior art, the high load is received at a line (in the case of a roller) or a point (in the case of a ball), and the pressure receiving surface (such as a bearing raceway surface) is used. ) May be locally deformed to hinder the smooth rotation of the second upper punch (6b).

[0010] Further, in a thrust bearing used under such a high load, the diameter of the rolling element becomes considerably large, so that the overall height of the device is increased. Therefore, the die set cannot be incorporated in a small press machine, and molding cannot be performed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a helical gear powder molding apparatus which can ensure smooth rotation of a rotary punch and can be incorporated in a small press.

[0012]

In order to achieve the above object,
In the present invention, a die having a helical shaped part formed on the inner peripheral surface corresponding to the teeth of the helical gear, and a reciprocally driven pressing member rotatably supported via a thrust bearing, and Equipped with a rotary punch formed with helical teeth that mesh with the die forming part, and a fixed punch fixed to the base plate. The powder supplied to the die is held from both sides by the rotary punch and the fixed punch inserted into the die. And pressing the rotary punch with a pressing member to compress the powder, and simultaneously rotate the rotary punch by guiding the helical teeth of the rotary punch in the circumferential direction at the die forming section. Was used as a plain bearing.

Here, the "thrust bearing" means a bearing which mainly supports an axial force and has a nominal contact angle exceeding 45 °. The term "sliding bearing" refers to a bearing that slides on a surface, and in the present invention, in particular, a thrust sliding bearing (a bearing that supports an axial force on a surface, and usually has a disk shape).
Use

Further, a helical tooth portion which meshes with a die forming portion may be provided at the tip of the fixed punch, and the die may be rotatably supported on a die plate by a radial slide bearing.

Here, the "radial sliding bearing" refers to a bearing which supports a shaft by a surface, and the surface and the shaft perform a sliding motion, and mainly receives a radial load.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view of a powder molding apparatus according to the present invention. This molding apparatus (1) has a main structure common to that of the conventional apparatus (FIG. 4).
Dice (3) having accommodation portion (2), die plate (4) accommodating dice (3), lower punch (5) inserted from below into accommodation portion (2) of die (3), accommodation portion ( 2) An upper punch (6) inserted from above, a pressurizing member (7) for pressing the upper punch (6), and a core rod (8) inserted into the housing part (2). Upper punch (6)
Is a first upper punch (6a) fixed to the pressing member (7).
And a second upper punch (6b: rotary punch) rotatably supported by a pressing member (7) via a thrust bearing (11A).
It is composed of On the other hand, lower punch (5: fixed punch)
Are fixed on a base plate (9) in a rest position. A helical shaped portion (3a) is formed on the inner peripheral surface of the die (3), and the outer peripheral surfaces of the first upper punch (6a) and the lower punch (5) mesh with the formed portion (3a). Possible helical teeth (61) (51) are respectively formed.

In the present invention, the thrust bearing (11A) disposed between the pressing member (7) and the first upper punch (6) is a sliding bearing. This thrust slide bearing (11A) is shown in FIG.
As shown in the figure, a lubricant filling portion (16) for filling a lubricant at one or a plurality of locations on a surface (sliding surface) of a base (15) made of a resin material or a metal material (for example, gunmetal) is provided. This is a so-called dry bearing formed by depression. The base (15) has a disk shape having a hole (17) in the center, and the drawing exemplifies a base (15) divided into four parts.

As the lubricant, a solid lubricant such as graphite is preferable, but a fluid lubricant such as grease or lubricating oil may be used depending on the use conditions. Further, the base (15) is impregnated with lubricating oil. Oil-impregnated bearings may be used. The base (1) is made of resin material with low friction and excellent sliding characteristics.
By forming 5), the lubricant may be omitted,
In this case, there is an advantage that it is not necessary to supply the lubricant.

As described above, when the bearing (11A) between the pressing member (7) and the second upper punch (6b) is a thrust sliding bearing, the load from the pressing member (7) during powder compression is increased. Since the pressure can be received on the surface, it is possible to prevent local deformation of the pressure receiving surface, which is a problem when a rolling bearing is used. Therefore, even when the powder is compressed, the second upper punch (6b)
Can ensure a smooth rotation. Generally, a sliding bearing can have a smaller wall thickness (axial width) than a rolling bearing having the same allowable load. Therefore, the overall height of the device (1) should be lower than a conventional product (specifically, about 200 mm). Can be. Therefore, it can be incorporated into a small press machine.

Conventionally, as shown in FIG. 4, a pair of thrust bearings (11a) for supporting the second upper punch (6b) are vertically arranged. Because the smooth rotation of the punch (6b) is ensured,
It is sufficient to dispose the thrust bearing (11A) only on one of the upper and lower sides. Therefore, from this point as well, the overall height of the apparatus can be reduced.

Conventionally, a die (3) is supported by a pair of upper and lower thrust bearings (11b) with respect to a die plate (4). As shown in FIG. ) Can also be substituted. That is, between the die (3) and the die plate (4), it is necessary to consider the rotational movement during the powder compaction as between the pressing member (7) and the first upper punch (6). Absent. Therefore, axial pressure resistance is not so required for the bearing in this part,
Therefore, no particular problem occurs even when the radial bearing (11B) is used. When the radial bearing (11B) is used in this manner, the axial width of the bearing portion of the die (3) and the axial width of the die (3) itself can be made shorter than those of the conventional device. The overall height can be further reduced. The bearing (11B) may be a rolling bearing, but is preferably a cylindrical sliding bearing for further miniaturization and simplification.

FIG. 2 shows an embodiment in which a radial bearing (11C) is interposed between the outer peripheral surface of the second upper punch (6b) and the pressing member (7). Since almost no radial force acts on the second upper punch (6b), this type of bearing (11C) is basically unnecessary, but by using the bearing (11C), the second upper punch (6b) can be used. The rotation operation of (6b) can be further smoothed. This radial bearing (11C)
May be a rolling bearing, but is preferably a sliding bearing from the viewpoint of further miniaturization and simplification.

[0024]

According to the present invention, since the thrust bearing between the rotary punch and the pressing member is a sliding bearing, a smooth rotary motion of the rotary punch can be ensured even when the powder is compressed. Further, the overall height of the die set can be made lower than that of the conventional product, and the die set can be incorporated into a small press machine.

By providing a helical tooth portion at the tip of the fixed punch for engaging with the die forming portion and supporting the die rotatably with respect to the die plate with a radial sliding bearing, the overall height of the die set can be further reduced. it can.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a powder molding apparatus according to the present invention.

FIG. 2 is an enlarged sectional view showing another embodiment of the present invention.

FIG. 3 is a plan view of a thrust slide bearing.

FIG. 4 is a longitudinal sectional view of a conventional device.

[Explanation of symbols]

 2 Housing part 3 Die 3a Molding part 4 Die plate 5 Fixed punch (lower punch) 6b Rotary punch (second upper punch) 7 Pressing member 9 Base plate 11A Thrust bearing 51 Helical teeth (lower punch side) 61 Helical teeth ( Upper punch side)

Claims (2)

[Claims] 1. A die having a helical shaped portion formed on an inner peripheral surface corresponding to a tooth portion of a helical gear, and a tip end rotatably supported by a reciprocatingly driven pressing member via a thrust bearing. A rotary punch formed with a helical tooth portion meshing with a die forming portion, and a fixed punch fixed to a base plate, and the powder supplied to the die is supplied from both sides by a rotary punch and a fixed punch inserted into the die. An apparatus for rotating the rotary punch by holding and pressing the rotary punch with a pressing member to compress the powder and simultaneously guide the helical teeth of the rotary punch in the circumferential direction at the die forming portion, wherein the thrust A helical gear powder molding machine with sliding bearings. 2. The helical gear powder molding apparatus according to claim 1, wherein a helical tooth portion meshing with the die forming portion is provided at the tip of the fixed punch, and the die is rotatably supported with respect to the die plate by a radial slide bearing. .