JP2653201B2 - Helical gear mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a mold for forming a helical gear by cold extrusion.

(Prior Art) As shown in FIG. 9, a conventional molding die for forming gears by cold extrusion is provided with a gear tooth profile 191 on the inner peripheral surface of a cylindrical hole 192 formed in a die container 19. The mandrel 21 is concentrically inserted into this hole, and a ring-shaped material 4 is inserted into an annular gap between the inner peripheral surface of the hole 192 and the outer peripheral surface of the mandrel 21.
Insert Then, the upper mold 20 is inserted into the annular gap, the upper mold 20 is pushed down in the direction of the arrow, and a pressing force is applied to the material 4 so that the material 4 passes through the tooth shape 191.
01 was cold extruded.

In the above conventional example, a tooth profile is formed on the outer periphery of the material. On the other hand, as a conventional example in which a tooth profile is formed on the inner peripheral surface of the material as shown in FIG. 10, the material 4 is inserted into a cylindrical hole 192 formed in the die container 19, and The lower end is supported by the backup 23, and the tooth profile 22
The mandrel 22 formed with 1 is inserted into the material 4, and the teeth 401 are cold-extruded on the inner peripheral surface of the material 4 while applying a pressing force to the mandrel 22 in the direction of the arrow to push the mandrel 22 into the material 4. Was like that.

Japanese Patent Application Laid-Open No. 63-309345 discloses a molding die shown in FIG. This mold is a die container
An annular convex portion 193 is provided on the inner peripheral surface of the cylindrical hole 192 opened in 19, and the mandrel 22 formed with teeth 221 on the outer periphery of the tip is concentric with the tooth 221 upward in the cylindrical hole 192. The cap-shaped material 4 is inserted from above the cylindrical hole 192. Then, the upper mold 20 inserted into the cylindrical hole 192 is pushed down in the direction of the arrow. When the upper die 20 is pushed down, the material 4 receives a pressing force and the outer peripheral surface thereof is
While being pressed in the radial direction, the mandrel 22 is pressed against the teeth 221 and descends, and the teeth are cold-formed on the inner surface thereof.

(Problems to be Solved by the Invention) In the above conventional example, the one shown in FIG. 9 has a straight outer peripheral surface of the mandrel 21, and the one shown in FIG. 10 has a straight inner surface of the cylindrical hole 192. Since there is no pressing force in the radial direction of the material, the pressing force between the tooth forming part and the tooth mold of the material is insufficient, and as shown in FIG. As a result, there is a problem that the sinkage 403 occurs, and the accuracy of the gear is reduced, sometimes resulting in a defective product. and again,
In FIG. 10, since the lower end of the material 4 is supported by the backup 23, when the thickness of the material 4 is small, it becomes difficult to support the material 4 by the backup 23, and the thickness of the material is limited. There is a problem.

In FIG. 11, the pressing force is applied in the radial direction of the material by the convex portion 193, but the mandrel is used.
22 has teeth 221 formed up to its tip, and there is no cylindrical portion that fits on the inner surface of the cap-like material.Therefore, at the first time when the teeth are formed on the inner surface of the cap-like material at the tip of the mandrel 22, the pressing force is There is a problem that sink 403 occurs as shown in FIG. That is, before cutting teeth on the inner surface of the cap-like material at the tip of the mandrel 22, if a pressing force is applied in the radial direction of the cap-like material by the convex portion 193, the interior of the cap-like material is hollow, The inner and outer diameters of the cap-shaped material are extruded and deformed in the inner diameter direction, so that highly accurate teeth cannot be formed, and the appearance of the cap is impaired. Therefore, it is necessary to press the outer periphery of the material with the convex portion 193 at the same time as the teeth are formed on the inner surface of the material, and the material insertion port side of the convex portion 193 is inclined to allow the material to enter. At the moment when the teeth are formed on the inner surface of the cap-like material at the end of the mandrel 22, the pressing force is insufficient by the amount of the inclination, and there is a problem that sink marks also occur as shown in FIG.

The present invention applies a pressing force in the radial direction of the material before forming the teeth on the inner surface of the material, and at the moment of forming the teeth,
An object of the present invention is to provide a mold for a helical gear which has a pressing force substantially equal to the maximum pressing force and prevents sink marks from occurring.

(Means for Solving the Problems) A means according to the present invention for solving the above problems includes a die or a die container having a cylindrical hole, and a mandrel inserted concentrically into the cylindrical hole. A helical gear forming die having a material insertion port on one side of the annular gap, wherein the outer diameter of the mandrel inserted concentrically into the cylindrical hole is defined by the material insertion port side. A cylindrical portion having a diameter substantially equal to the inner diameter of the cylindrical portion, and forming a tooth profile of a convex gear on one of the outer peripheral surface of the cylindrical portion and the cylindrical hole and the outer peripheral surface of the cylindrical portion or the circumferential shape. A ring-shaped protrusion is provided in one of the holes to face the gear tooth profile, the land length of the ring-shaped protrusion is shorter than the land length of the gear tooth profile, and the ring-shaped protrusion is formed. To the specified insertion angle Wherein the starting point of the inclined surface is located closer to the material insertion port than the starting point of the introduction angle of the tooth profile.

(Operation) With the above-described configuration, the molding of the internal gear helical gear will be described as an example. The cylindrical material supplied into the annular gap between the mandrel and the die is the tooth-shaped material formed on the mandrel. A cylindrical portion having a diameter on the insertion port side substantially equal to the inner diameter of the material is supported so that deformation of the material in the inner diameter direction is restricted. And when the above material is pressed down by the pressing force due to the lowering of the sleeve mandrel,
In this material, the inner peripheral surface of the hole of the die faces the tooth profile of the mandrel, and the land length is shorter than the land length of the tooth profile formed on the outer periphery of the mandrel. Before the teeth are formed on the inner surface of the material, the angled inclined surface is formed such that the starting point of the inclined surface is located closer to the material insertion port than the starting point of the introduction angle of the tooth profile. A pressing force is applied in the radial direction. Immediately before the teeth are formed on the inner peripheral surface of the material, the teeth at the initial stage are formed on the inner surface of the material while a pressing force close to the maximum pressing force is applied in the radial direction of the material. Subsequently, when the material is pressed down by the sleeve mandrel and pressed down under the pressing force, the material receives the maximum pressing force in the radial direction, and the teeth are formed on the inner surface thereof.

(Example) Hereinafter, a mold for an internal gear helical gear will be described as an example of the present invention, and will be described in detail. In FIG. 1, a predetermined tooth profile 101 is formed on an outer peripheral surface of a mandrel 1, and a cylindrical portion having a diameter substantially equal to the inner diameter of the material 4 is provided on a material 4 insertion side.
On the outlet side of the material 4, an outlet-side cylindrical portion 103 having a smaller diameter than the inner diameter of the material 4 is formed to facilitate removal of a tooth-shaped product. The tooth profile 101 has a portion (hereinafter referred to as a tooth profile land) C for processing a normal tooth. The length of the tooth profile land C is determined by the lead angle of the gear, the module, the material of the material 4, and the like. Also, on the insertion side of the material 4 of the tooth profile land C, the material 4
The inclined surface 104 having the introduction angle β is formed. Reference numeral 105 denotes an inclined surface formed on the exit side of the material 4 of the tooth-shaped land C, and serves to reinforce the tooth-shaped land C.

Next, the die 2 is provided with a cylindrical hole 201 having an inner diameter substantially equal to the outer diameter of the material 4. Then, in a state where the mandrel 1 is inserted and positioned in the cylindrical hole 201, at a position facing the tooth profile 101 provided on the mandrel 1,
A ring-shaped convex portion 202 having a height of the thickness reduction allowance B is formed. The length A of the top of the projection 202 (hereinafter referred to as a projection land) is shorter than the tooth land C. The positional relationship between the tooth profile 101 and the projection 202 is determined by the tooth profile 101 at the start end of the inclined surface 203 having the introduction angle α formed on the insertion side of the material 4 of the projection 202.
The starting end of the inclined surface 203 having the introduction angle α is shifted from the starting end of the inclined surface having the introducing angle β by the distance E, and the starting end of the inclined surface 203 having the introducing angle α is closer to the insertion side of the material 4. Positioning is performed so that the difference between C and the end of the convex land A is within a range of zero from the dimension D (hereinafter referred to as offset). The thickness reduction B, the introduction angle α, and the offset D are also determined by the lead angle of the gear, the module, the material of the material 4, and the like.

3 is a cylindrical hole 20 formed in the outer periphery of the mandrel 1 and the die 2.
2 is a sleeve mandrel inserted into an annular gap between the sleeve mandrel and the inner periphery of the sleeve mandrel;

The overall assembly will be described with reference to FIG.
The lower end of the mandrel 1 is fitted into the positioning hole 602 of the pressure plate 601 and fastened and fixed by bolts 7. A sleeve knockout 5 slidably fitted to the tooth portion 101 of the mandrel 1 is provided. The sleeve knockout 5 is raised by a knockout 10 via a knockout pin 8, and extrudes a product formed with a tooth mold and discharges the product out of the mold. The die 2 is positioned on the lower die body 16,
Lower mold body reinforced with stress ring 11 and bolt 12
It is fastened and fixed to 16. The sleeve mandrel 3 is fastened and fixed to the upper die 15 by a bolt 14 via a retainer 13. The sleeve mandrel 3 is raised and lowered by a pressure machine (not shown).

By pressing down the sleeve mandrel 3, the pressing force acting on the material 4 and the mandrel 1 is applied to the pressure receiving plate 9 via the pressure plate 601 and finally received by a pressure machine (not shown) supporting the pressure receiving plate 9. It has become.

3 and 4 show the mandrel 1
Are positioned by the backup 5, and the backup 5 receives the pressing force acting on the material 4 and the mandrel 1 when the sleeve mandrel 3 is pressed down. The die 2 is reinforced by a stress ring 8 and fastened and fixed to a lower mold body 14 by a bolt 10 via a retainer 9.
The load applied to the die 2 is transmitted to the pressure plate 7 via the spacer 6 and is received by the lower die body 14. Since the lower mold body 14 is fixed to a base of a pressure machine (not shown), the above load is ultimately received by the machine body.

The operation of the present embodiment having such a configuration will be described below. 2 to 4, after inserting the material 4 into the annular gap between the mandrel 1 and the die 2, the sleeve mandrel 3 is lowered to apply a pressing force to the material 4. With this pressing force, the inner surface of the material 4 is processed by the tooth profile 101 of the mandrel 1 while the pressing force is applied in the radial direction by the projection 202. The processing of the teeth at this time will be described in more detail.

In FIGS. 5 and 6, the material 4 is pushed down by the lowering of the sleeve mandrel 3 and no pressing force is applied in the radial direction of the material 4 until the material 4 reaches the position of the starting point L0 of the inclined surface 203. . This point is the origin in Fig. 6.
Corresponds to L0. Then, as the material 4 further descends, the pressing force P increases as shown in FIG. The material 4 is pushed down so that the tip of the material 4 is at the position of L1, that is, L1 in FIG.
In the position, the tip of the material 4 is located at the start of the introduction inclined portion of the tooth mold 101 with a pressing force of P2 close to the maximum pressing force P1,
In this state, the teeth are formed on the inner surface of the material 4. Thus, before the teeth are formed on the inner surface of the material 4, that is, while the tip of the material 4 advances from the position L0 to the position L1, the material 4
The pressing force can be applied in the radial direction because the cylindrical portion 102 having an outer diameter substantially equal to the inner diameter of the material 4 is inserted into the material 4,
This is because the deformation of the inner surface of the material 4 in the radial direction is restricted. And when the material 4 descends further, the pressing force starts from P2
While the pressure is increased to P1, teeth are formed on the inner surface of the material 4 from the introduction inclined portion to the tooth lands gradually. In this embodiment, when the tip of the material 4 is at the position of L2, the pressing force is the maximum P1.
, And the leading angle of the material 4 is set so that the introduction angle α, the thickness reduction B, and the convex land A slightly overlap the tooth land of the tooth form 101. The position of L2 is set when the material of the material 4 is relatively soft, and when the material is relatively hard, the position of the L2 is brought close to the L1 and the pressing force P2 is set to the maximum at the initial stage of the tooth forming start. The pressing force should be made closer to P1. As described above, by setting the position of L2, the thickness reduction B (maximum pressing force P1) and the convex land A according to the material of the material 4, the frictional force between the material 4 and the mandrel 1 and the die 2 is obtained. Is reduced as much as possible, the pushing force of the sleeve mandrel 3 is reduced, the size of the entire apparatus is reduced, and the processing of a large gear of the tooth profile module is enabled. Next, when the tip of the material 4 reaches the position of L3, it is the stage where the formation of the teeth on the inner surface of the material 4 has already been completed. And the tooth is not machined between offsets D.

That is, in the case of the internal gear helical gear, as shown in FIG. 7, the teeth are inclined with respect to the vertical force F given by the lowering of the sleeve mandrel 3, so that this force F is a horizontal component force. The balance between F1 and frictional force F2. Therefore, when the maximum pressing force P1 is applied to the end,
As shown in FIG. 8, a large component F1 is applied to the tooth 402 on which the tooth is already formed, and the tooth 401 is deformed.
The offset D serves to prevent this deformation.

Thus, while the material 4 is being pushed down by the sleeve mandrel 3 and its tip moves between G of L0 and L2, the material 4 is gradually given a pressing force in the radial direction,
At the pressing force of P2 close to the maximum pressing force P1, teeth are started to be formed on the inner surface, and then the maximum pressing force P1 is given at the convex land A, the teeth are formed at the tooth land C, and the teeth are formed at L3 to L4. While moving between H, deformation of the tooth formed by the offset D is prevented, and a highly accurate tooth is processed.

The inner surface of the material 4 is guided by the cylindrical portion 102 and is inserted into the annular gap between the mandrel 1 and the die 2 and receives a pressing force by the sleeve mandrel 3. It is possible to form teeth even if it is thin.

When the processing is completed in this manner, the sleeve mandrel 3 is raised, and in the case of FIG. 2, the knockout 10 is raised, and the processed product is pushed out by the sleeve knockout 5 and discharged out of the mold. It is carried out of the die set by a robot or the like. In the embodiment shown in FIGS. 3 and 4, the material 4 is continuously supplied and continuously processed, and the processed product is flush with the pressure plate 7 with the backup 5 lowered. The pushers 15 fall sequentially upward, slide in a through hole 16 formed in the spacer 6, and are pushed out by chutes 17 and 18 by a reciprocating pusher 15 to be dispensed.

In the above description, the case where the helical gear is formed on the inside of the material 4 is described as an example. However, when the helical gear is formed on the outer periphery of the material 4, the convex portion 202 is formed on the outer periphery of the mandrel 1 in FIG. And the tooth mold 101 may be formed on the inner peripheral surface of the cylindrical hole 201 of the die 2.

(Effects of the Invention) As described in detail above, according to the present invention, the diameter of the material insertion port side of the mandrel is made to be a cylindrical portion having a diameter substantially equal to the inner diameter of the material, and the outer peripheral surface of the cylindrical portion or the hole of the die is formed. A tooth profile of a convex gear is formed on one of the inner peripheral surfaces, and a ring-shaped convex portion is provided on the other of the outer peripheral surface of the cylindrical portion or the inner peripheral surface of the hole of the die in opposition to the tooth profile, The length of the land of the ring-shaped protrusion is shorter than the length of the land of the tooth shape formed on the outer periphery of the mandrel, and the material insertion port side of the ring-shaped protrusion is formed into an inclined surface having a predetermined introduction angle, Since the starting point of the surface is located closer to the material insertion port than the starting point of the tooth profile introduction angle, it is possible to apply a pressing force in the radial direction of the material before forming teeth on the inner surface of the material.

As a result, at the moment when the teeth are formed on the inner surface of the material, the pressing force is close to the maximum pressing force, and the formed teeth do not have sink marks.

In addition, by selecting the lead angle α of the convex part, the lead angle β of the tooth form, the thickness B of the convex part, the land of the convex part and the tooth form according to the material of the material, the lead angle of the gear and the tooth profile module, In addition to the material and the gear specifications, for example, a gear suitable for a large module gear, the mold transferability can be improved, and the gear can be machined with high precision by a synergistic effect with the prevention of sink mark.

Further, depending on the material of the material, the lead angle of the gear and the tooth profile module, the introduction angle α of the convex portion, the introduction angle β of the tooth profile,
By selecting the thickness B of the convex portion, the convex portion and the land of the tooth shape, the friction force between the die and the mandrel and the material is reduced, and the pushing force of the sleeve mandrel is reduced,
The entire device can be reduced in size.

In addition, since a cylindrical portion having an outer diameter substantially equal to the inner diameter of the material is inserted into the material, the material is inserted into the annular gap between the die and the mandrel, and the material is pressed by the sleeve mandrel, so that the thin material is used. But you can process your teeth.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an essential part of one embodiment of the present invention, FIG. 2 is a longitudinal sectional view of an entire assembly of a molding die, FIG. FIG. 5 is a longitudinal sectional view showing a state in which processed products are dispensed in the embodiment of FIG. 3, FIG. 5 is an explanatory diagram showing a longitudinal section of a main part, and FIG. 6 corresponds to FIG. 7 is a diagram showing the relationship between the pressing force and the movement of the material shown in FIG. 7, FIG. 7 is a schematic diagram showing the relationship between the formed teeth and the pressing force in the vertical direction of the sleeve mandrel, and FIG. It is a longitudinal section showing a processing state. FIG. 9 is a longitudinal sectional view of a conventional external tooth forming mold, FIG. 10 is a longitudinal sectional view of a conventional internal tooth forming mold, and FIG. 11 is a longitudinal sectional view of a conventional pressing mold to which a pressing force is applied. FIG. 12 is a schematic diagram showing tooth sinkage of a molded product. DESCRIPTION OF SYMBOLS 1 ... Mandrel 101 ... Tooth part 102 ... Cylindrical part 2 ... Die 201 ... Cylindrical hole 202 ... Convex part 203 ... Slope surface 3 ... Sleeve mandrel 4 ... Material α ... Convex part introduction angle β …… Tooth introduction angle A …… Protrusion land C …… Tooth land

Claims (1)

(57) [Claims] An annular gap is formed between a die or a die container having a cylindrical hole and a mandrel concentrically inserted into the cylindrical hole, and a material insertion port is provided on one side of the annular gap. In the molding die of a helical gear having a cylindrical portion, the outer diameter of the material insertion port side of the mandrel inserted concentrically into the cylindrical hole has a diameter substantially equal to the inner diameter of the material, and the outer peripheral surface of the cylindrical portion or A ring-shaped convex portion is formed on one of the cylindrical holes, and a convex gear tooth is formed on the outer peripheral surface of the cylindrical portion or on the other of the cylindrical holes. A land length of the ring-shaped protrusion is made shorter than a land length of the tooth profile of the gear, and a material insertion opening side of the ring-shaped protrusion is formed as an inclined surface having a predetermined introduction angle; Starting point of the tooth profile Mold helical gear, characterized in that located in the fee insertion port side.