JP2008073701A - Apparatus and method for forging gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for forging a gear, which has a simple structure and excellent durability and by which a helical gear can precisely be manufactured, and a method for forging the gear. <P>SOLUTION: The gear forging apparatus 1 is provided with; a punch 2 for pressurizing the upper end surface in the axial direction of a base material 70 for the gear; a die 4 for forming a spiral tooth face on the outer circular face of the base material 70 for the gear; and the die sleeve 6 for receiving the lower end surface in the axial direction of the base material 70 for the gear so as to be opposite to the punch 2. The die 4 is rotatable around a die case 5 and the die sleeve 6, in a state of being held in the die case 5. The gear forging apparatus 1 is constituted so that when after forging, the helical gear 7 is taken out from a tooth forming hole 41 of the die 4, the die 4 is made to rotate around the die case 5, the helical gear 7 and the die sleeve 6 by pushing down the die 4 against the energizing force of a gas cushion 51 with a pushing-down rod 31 so as to take out the helical gear 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gear forging device and a gear forging method for producing a helical gear from a gear material.

  As an apparatus or a method for manufacturing a gear (helical gear) having a wound tooth surface that hangs on the outer peripheral surface by performing forging such as cold forging, there is one disclosed in Patent Document 1, for example. In Patent Document 1, in a state where a gear material is arranged in a tooth forming hole of a die having a helical tooth surface, both end surfaces in the axial direction of the gear material are pressed by a punch and a die sleeve. Thus, a gear having a wound tooth surface that hangs on the outer peripheral surface is formed in the die forming surface of the die.

Moreover, in patent document 1, the die | dye is arrange | positioned rotatably with respect to a die case, and the die sleeve is arrange | positioned rotatably with respect to a die | dye and a die sleeve holder (fixed part).
And after shaping | molding a gearwheel, the die sleeve advances while rotating itself along the tooth trace in the shaping | molding surface of a die | dye, and the gearwheel after shaping | molding is taken out from die | dye. As a result, deformation of the formed gear is prevented, and a gear with excellent dimensional accuracy is manufactured.

However, the conventional gear forging device or the gear forging method has the following problems. That is, in Patent Document 1, it is necessary not only to make the die rotatable but also to make the die sleeve rotatable. Therefore, the structure of the apparatus is complicated.
In addition, a spiral groove and a pin that engages with the spiral groove are formed between the die and the die case, and a spiral groove is also formed between the die sleeve and the die sleeve holder. A pin engaging with the pin is formed.

  For this reason, due to the clearance between the spiral groove and the pin, not only does the die rattle against the die case, but the die sleeve may rattle against the die sleeve holder. As a result, when the gear is formed, the helical tooth surface in the die forming hole of the die and the helical tooth surface on the screw sliding surface of the die sleeve are likely to interfere (collision). . Therefore, the durability of the die and the die sleeve may be deteriorated.

  Further, in Patent Document 2, a helical gear is manufactured using a molding die that is coaxially provided with a tooth forming portion having a plurality of tooth shapes twisted obliquely with respect to the axis and a shaft portion forming portion having a cylindrical hole. A method is disclosed. Then, at least one of the tooth forming portion and the shaft portion forming portion is rotatably arranged, and at the time of removing the molded helical gear from the forming die, at least one of the tooth forming portion and the shaft portion forming portion. It is taken out by rotating. Moreover, in patent document 2, the device for preventing a die from rotating at the time of shaping | molding and rotating a die only at the time of taking out a helical gear is also performed.

  However, in Patent Document 2, a helical gear is formed by performing an extrusion process, and at the same time as forming, the accuracy of the tooth surface may deteriorate. That is, the helical gear is formed by extruding the material disposed in the cylindrical hole of the shaft forming portion toward the tooth shape of the tooth forming portion by a punch. Therefore, the material is pushed out in the axial direction against the tooth surface twisted in a spiral shape with respect to the axial direction, and the accuracy of one side surface and the other side surface of each tooth surface of the helical gear is different, There is a risk that the accuracy of will deteriorate.

Moreover, in patent document 2, the die | dye is rotated using the force which pushes up the helical gear which is a product. For this reason, the tooth surface of the helical gear may be deformed, which is not sufficient for accurately forming the gear.
Further, in Patent Document 2, when the rotation of the tooth forming portion is controlled by the cylinder, when the ejected helical gear is taken out from the inside of the tooth forming portion by the ejector, the lifting operation of the ejector and the stroke operation of the cylinder are performed. It becomes necessary to synchronize with the motor, and control when taking out the helical gear becomes difficult.

JP 2004-98159 A JP 2002-346680 A

  SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and has a gear forging device and a gear capable of manufacturing a helical gear with a simple structure and excellent durability of the device. It is intended to provide a forging method.

The first invention is an apparatus for forging a helical gear from a gear material,
Punch for pressing the axial upper end surface of the gear material, a punch holder for holding the punch, a die for forming a spiral tooth surface on the outer peripheral surface of the gear material, and a die case for holding the die And a die sleeve that faces the punch and receives the lower end surface in the axial direction of the gear material, and a die base that fixes the die sleeve and the die case.
The die is rotatable with respect to the die case and the die sleeve, and has a tooth forming hole for forming the helical tooth surface.
Between the outer peripheral surface of the die and the inner peripheral surface of the die case that holds the outer peripheral surface, a spirally wound groove is formed on either side, and on the other side, the spirally wound groove is engaged. Mating engagement protrusions are formed,
The punch is configured to form a forging space for forging the helical gear together with the die forming hole of the die and the die sleeve,
In the punch holder, a push rod that pushes down the die is arranged to be movable up and down,
The die sleeve has a tooth mold outer peripheral surface along the shape of the tooth mold forming hole, and is arranged in a state where the tooth mold outer peripheral surface is engaged in the tooth mold forming hole,
The tooth surface in the tooth mold forming hole, the tooth surface on the outer peripheral surface of the tooth mold, and the spiral groove are formed on the same lead,
When the helical gear after forging is taken out from the tooth forming hole of the die, the die is pushed down by the push rod, so that the die is removed from the die case, the helical gear, and the die sleeve. The helical forging device is configured to take out the helical gear by rotating with respect to the gear (claim 1).

  A gear forging device of the present invention includes the punch, punch holder, die, die case, die sleeve, and die base, and the die rotates with respect to the die case and the die sleeve while being held in the die case. The punch holder is provided with a push rod which pushes down the die so as to be movable up and down.

  When forging a helical gear from a gear material, the axial upper end surface of the gear material is punched with the die sleeve receiving the axial lower end surface of the gear material arranged in the forging space. The helical gears are forged in the forging space by crushing with pressure and crushing the gear material. At this time, the punch is lowered toward the die, and a forging space is formed by the die forming hole, punch and die sleeve of the die. The helical gear can be closed and forged by pressing the outer peripheral surface of the gear material against the tooth forming hole of the die. Thereby, it can prevent that the precision of one side and the other side in each helical tooth surface of the helical gear after forging can differ, and the precision of a helical tooth surface is stabilized. be able to.

  Next, the push rod is lowered with respect to the punch holder, and the die is pushed down by the push rod. At this time, the die in a state in which the helical gear after forging is held in the tooth forming hole is the same as the helical gear after forging because the engaging protrusion moves relative to the helical groove. The lead (which indicates the distance traveled in the axial direction when it makes one revolution) can be lowered while forcibly rotating with respect to the die case. Thereby, it is possible to prevent the force that the push rod pushes down the die from being directly applied to the helical gear after forging. Therefore, it is possible to prevent the helical gears from being taken out of the tooth-forming holes while preventing the accuracy of the pair of side surfaces in each helical tooth surface of the helical gear after forging from being deteriorated.

  In the present invention, the die sleeve does not need to be rotated and is fixed in the gear forging device both when the helical gear is forged and when the helical gear after forging is taken out. be able to. Therefore, it is not necessary to form a helical groove for rotating the die sleeve, and it is possible to prevent the die sleeve from rattling during forging of the helical gear. As a result, during helical gear forging, interference (collision) occurs between the helical tooth surface in the die forming hole of the die and the helical tooth surface on the outer peripheral surface of the die sleeve. Can be prevented from occurring. Therefore, durability of the die and the die sleeve can be improved.

Furthermore, in the present invention, the helical gear can be taken out from the tooth forming hole by directly pressing down the die with the push rod instead of rotating the die through the helical gear after forging. Thereby, it is possible to prevent the helical gear from being deformed, and it is possible to manufacture a helical gear excellent in accuracy. Further, in the present invention, it is not necessary to perform special control to rotate the die, and the structure of the gear forging device can be simplified.
Therefore, according to the gear forging device of the present invention, the structure of the device is simple and the durability of the device is excellent, and a helical gear can be manufactured with high accuracy.

A second invention includes a punch that pressurizes an axial upper end surface of the gear material, a punch holder that holds the punch, a die that forms a wound tooth surface on the outer peripheral surface of the gear material, Using a gear forging device having a die case that holds a die, a die sleeve that receives the lower end surface in the axial direction of the gear material facing the punch, and a die base that fixes the die sleeve and the die case, A method of forging a helical gear from a gear material,
The die is rotatable with respect to the die case and the die sleeve, and has a tooth forming hole for forming the helical tooth surface.
Between the outer peripheral surface of the die and the inner peripheral surface of the die case that holds the outer peripheral surface, a spirally wound groove is formed on either side, and on the other side, the spirally wound groove is engaged. Mating engagement protrusions are formed,
The punch is configured to form a forging space for forging the helical gear together with the die forming hole of the die and the die sleeve,
In the punch holder, a push rod that pushes down the die is arranged to be movable up and down,
The die sleeve has a tooth mold outer peripheral surface along the shape of the tooth mold forming hole, and is arranged in a state where the tooth mold outer peripheral surface is engaged in the tooth mold forming hole,
The tooth surface in the tooth mold forming hole, the tooth surface on the outer peripheral surface of the tooth mold, and the spiral groove are formed on the same lead,
The gear material is crushed by pressing the axial upper end surface of the gear material with the punch while the axial lower end surface of the gear material disposed in the forging space is received by the die sleeve. A forging step of forging the gear in the forging space,
By pushing down the die in a state where the helical gear after forging is held in the tooth forming hole by the push rod, the die is moved against the die case, the helical gear and the die sleeve. A gear forging method characterized by including a removing step of rotating and taking out the helical gear from the tooth forming hole of the die.

In the gear forging method of the present invention, a helical gear is manufactured from a gear material using the gear forging device described above.
Specifically, in the forging step, by pressing the axial upper end surface of the gear material with a punch while the axial lower end surface of the gear material disposed in the forging space is received by the die sleeve. The gear material is crushed to forge a helical gear in the forging space. At this time, the punch is lowered toward the die, and a forging space is formed by the die forming hole, punch and die sleeve of the die.

  Next, in the above-described extraction step, after the helical gear is forged, the pressing rod is lowered with respect to the punch holder, and the die is pressed down by the pressing rod. At this time, the die in a state in which the helical gear after forging is held in the tooth forming hole is the same as the helical gear after forging because the engaging protrusion moves relative to the helical groove. The lead can be lowered while forcibly rotating with respect to the die case. And the helical gear can be taken out from the inside of the tooth forming hole by lowering the die.

  Therefore, according to the gear forging method of the present invention, similar to the above-described gear forging device invention, the structure of the device is simple and the durability of the device is excellent. Can do.

A preferred embodiment in the first and second inventions described above will be described.
In the first invention, the die is biased upward by biasing means disposed on the die base, and the punch is configured to push down the die against the biasing force of the biasing means. The push rod is preferably configured to push down the die against the biasing force of the biasing means.
In the second invention, the die is biased upward by biasing means disposed on the die base. In the forging step, the punch resists the biasing force of the biasing means. The helical gear is forged while pushing down the die, and in the take-out step, the punch is retracted from the die, and the die is further moved against the biasing force of the biasing means by the pressing rod. It is preferable to take out the helical gear by pushing down.

In these cases, it is possible to easily form a structure in which the die can be raised and lowered by using the biasing means.
The punch can forge the helical gear while pushing down the die against the biasing force of the biasing means. Thus, the forging space can be stably formed by the die forming hole, punch and die sleeve of the die, and the helical gear can be stably forged. Further, the push rod can further push down the die against the biasing force of the biasing means. As a result, the helical gear after forging can be easily taken out from the tooth forming hole of the die, and after the helical gear is taken out, the die is easily moved to the original position by the biasing force of the biasing means. Can be restored.

The urging means is preferably a gas cushion that generates a repulsive force using the pressure of gas. In this case, a structure in which the die can be raised and lowered stably can be formed more easily.
The urging means can also be configured with a compression spring, a hydraulic cylinder, or the like.

  Preferably, the engaging protrusion is provided with a roller that moves with the engaging protrusion while rotating in the helical groove. In this case, the amount of wear between the engaging protrusion and the spiral groove can be reduced, and the durability of these can be improved.

  The gear material may have a cylindrical shape with a shaft hole, and the punch may have a mandrel portion that is inserted into the shaft hole of the gear material. 5). In this case, a helical gear having a shaft hole can be manufactured with high accuracy.

Hereinafter, embodiments of the gear forging device and the gear forging method according to the present invention will be described with reference to the drawings.
As shown in FIGS. 1, 2, and 4, the gear forging device 1 of this example includes a helical gear 7 (hereinafter referred to as a helical gear) having a spiral tooth surface 71 that hangs from the gear material 70 to the outer peripheral surface 701. The gear 7). The gear forging device 1 forms a punch 2 that pressurizes the axial upper end surface of the gear material 70, a punch holder 3 that holds the punch 2, and a wound tooth surface 71 that hangs on the outer peripheral surface 701 of the gear material 70. A die 4 that holds the die 4, a die sleeve 6 that faces the punch 2 and receives the lower end surface in the axial direction of the gear material 70, and a die base that fixes the die sleeve 6 and the die case 5 11.

The die 4 is rotatable with respect to the die case 5 and the die sleeve 6 while being held in the die case 5, and is urged upward by a gas cushion 51 as urging means, and The tooth forming hole 41 for forming the coiled tooth surface 71 on the gear material 70 is provided.
Further, between the outer peripheral surface of the die 4 and the inner peripheral surface of the die case 5 that holds the outer peripheral surface, a helical groove 54 is formed on either side, and the helical groove is formed on the other side. An engagement protrusion 43 is formed to engage with 54.

The punch 2 is held in the punch holder 3 and is configured to form a forging space 10 for forging the helical gear 7 together with the die 4 and the die sleeve 6. The punch holder 3 is provided with a push rod 31 that pushes down the die 4 against the urging force of the gas cushion 51 so as to be movable up and down.
The die sleeve 6 includes a tooth mold outer peripheral surface 61 that follows the shape of the tooth mold forming hole 41, and the tooth mold outer peripheral surface 61 is engaged in the tooth mold forming hole 41.

Further, the tooth surface lead in the tooth forming hole 41 of the die 4 (indicating the distance traveled in the axial direction when rotated once), the tooth surface lead in the tooth outer peripheral surface 61 of the die sleeve 6, and the helical winding. The lead of the groove 54 is set to be the same.
As shown in FIG. 3, the gear forging device 1 resists the urging force of the gas cushion 51 by the push rod 31 when taking out the forged helical gear 7 from the tooth forming hole 41 of the die 4. Then, by pushing down the die 4, the die 4 is rotated with respect to the die case 5, the helical gear 7 and the die sleeve 6, and the helical gear 7 is taken out.

Below, it explains in full detail with FIGS. 1-8 about the gear forging apparatus 1 and the gear forging method of this example.
As shown in FIG. 4, the gear material 70 of the present example has a cylindrical shape with a shaft hole 72, and the helical gear 7 manufactured in the gear forging device 1 of this example has the shaft hole 72. It is provided. In addition, spline-like tooth traces are formed in the shaft hole 72 of this example. As shown in FIG. 1, the punch 2 has a mandrel portion 21 that is inserted into the shaft hole 72 of the gear material 70, and the mandrel portion 21 has spline-like tooth traces in the shaft hole 72. Spline forming teeth 211 for forming are formed.
Note that the helical gear 7 manufactured by the gear forging device 1 has a shape that does not have the shaft hole 72 as shown in FIG. Thus, the shaft hole 72 may not have a spline-like tooth trace.

  As shown in FIGS. 1 and 2, a fitting recess 42 for fitting the lower end of the punch 2 is formed in the upper opening of the tooth forming hole 41 of the die 4. And the forge space 10 can be formed stably by the lower end part of the punch 2 being inserted in the insertion recessed part 42.

  The gas cushion 51 is disposed on the die base 11, and a movable portion 511 of the gas cushion 51 is provided with a die holding portion 52 provided with a thrust bearing 53 for allowing the die 4 to rotate. is there. The die 4 is rotatably disposed on the die holding portion 52 via a thrust bearing 53 and can be swung up and down by a gas cushion 51. The gas cushion 51 has a piston structure that strokes by the flow of gas, and generates a predetermined repulsive force using the pressure of the gas.

  Further, as shown in FIGS. 7 and 8, in this example, a spiral groove 54 is formed on the inner peripheral surface of the die case 5 that holds the outer peripheral surface of the die 4. An engagement protrusion (engagement pin) 43 that engages with the spiral groove 54 is provided. In addition, the helical groove 54 and the engagement protrusion 43 of the present example are provided on the inner peripheral surface of the die case 5 and the outer peripheral surface of the die 4 in order to stably slide the die 4 relative to the die case 5. Are formed at a plurality of locations.

In addition, the engaging protrusion 43 is provided with a roller 431 that moves in the spiral groove 54 together with the engaging protrusion 43 while rotating. By disposing the roller 431, the amount of wear between the engaging protrusion 43 and the spiral groove 54 can be reduced, and the durability of these can be improved.
Note that the helical groove 54 may be formed on the outer peripheral surface of the die 4, and the engaging protrusion 43 may be formed on the inner peripheral surface of the die case 5.

  Further, in this example, as shown in FIGS. 1 and 2, in order to prevent the die holding part 52 from rotating with respect to the die case 5, the die holding part 52 is provided along the vertical direction. A linear groove 521 is formed, and the die case 5 is formed with an engaging portion 55 that engages with the linear groove 521. Note that the linear groove 521 can be formed in the die case 5 and the engaging portion 55 can be formed in the die holding portion 52.

The die sleeve 6 is fixed to the die case 5 and is configured not to rotate as the die 4 rotates. Further, the die 4 is configured to rise or fall while rotating by sliding the tooth mold forming hole 41 along the tooth mold outer peripheral surface 61 of the die sleeve 6.
Although not shown in the drawings, the push rod 31 of this example is configured to be pressed by the hydraulic cylinder and to be lowered to push down the die 4.

Further, as shown in FIG. 1, the die base 11 of this example is a pressure plate that fixes the die case 5, the die sleeve 6, and the gas cushion 51. The die case 5 is fixed to the die base 11 via the coupling member 13. The die sleeve 6 is fixed to the die base 11 by a die sleeve holder 12. In addition, a stopper 56 that forms the rising end of the die 4 urged upward by the gas cushion 51 is disposed on the upper end surface of the die case 5.
The die case 5 and the coupling member 13 are fixed to the die base 11 via positioning pins and bolts, the die sleeve holder 12 is fixed to the die base 11 via positioning pins, and the die sleeve 6 is The die sleeve holder 12 is prevented from rotating via a rotation stopper pin.

Next, a method for forging the helical gear 7 using the gear forging device 1 will be described.
In forging the helical gear 7, first, as shown in FIG. 1, the gear material 70 is arranged in the tooth forming hole 41 of the die 4 at the position raised by the gas cushion 51 as an arrangement step. .
Next, as shown in FIG. 2, the punch 2 is lowered toward the die 4 as a forging process. At this time, the lower end portion of the punch 2 is inserted into the insertion recess 42 of the die 4, and the forging space 10 is formed by the tooth die forming hole 41 of the die 4, the punch 2 and the die sleeve 6. While the punch 2 pushes down the die 4 against the urging force of the gas cushion 51, the axial lower end surface of the gear material 70 is received by the die sleeve 6, and the axial upper end surface of the gear raw material 70 is received. Is pressed by the punch 2, the gear material 70 is crushed and the helical gear 7 is forged in the forging space 10.

  The helical gear 7 can be closed and forged by pressing the outer peripheral surface of the gear material 70 against the tooth forming hole 41 of the die 4. Thereby, it can prevent that the precision of one side 711 and the other side 712 in each helical tooth surface 71 of the helical gear 7 after forging is different, and the helical winding tooth surface 71. Can be stabilized (see FIG. 4).

Next, as shown in FIG. 3, as the take-out process, the punch 2 is retracted from the die 4 and the pressing rod 31 is lowered with respect to the punch holder 3. Then, the die 4 is further pushed down against the urging force of the gas cushion 51 by the push rod 31.
At this time, the die 4 in a state in which the helical gear 7 after forging is held in the tooth forming hole 41 is moved relative to the engagement projection 43 along the spiral groove 54, so that With the same lead as the helical gear 7, the lead can be lowered while forcibly rotating with respect to the die case 5.

Thereby, it is possible to prevent the force by which the push rod 31 pushes down the die 4 from being directly applied to the helical gear 7 after forging. For this reason, the accuracy of the pair of side surfaces 711 and 712 in each helical tooth surface 71 of the helical gear 7 after forging is prevented from deteriorating, and the helical gear 7 is moved from the inside of the tooth forming hole 41. It can be taken out.
Then, after taking out the helical gear 7 from the inside of the tooth mold forming hole 41, the die 4 can be easily returned to the original raised position by the urging force of the gas cushion 51.

  Further, in this example, the die sleeve 6 does not need to be rotated both when forging the helical gear 7 and when taking out the helical gear 7 after forging. Can be fixed. Therefore, it is not necessary to form a helical groove for rotating the die sleeve 6, and it is possible to prevent the die sleeve 6 from rattling when the helical gear 7 is forged. Thereby, when the helical gear 7 is forged, the helical tooth surface in the tooth forming hole 41 of the die 4 and the helical tooth surface in the tooth outer peripheral surface 61 of the die sleeve 6 are interposed. , Twisting or interference (collision) can be suppressed. Therefore, durability of the die 4 and the die sleeve 6 can be improved.

Furthermore, in this example, the die 4 is not rotated via the helical gear 7 after forging, but the die 4 is directly pushed down by the push rod 31 so that the helical gear 7 is moved from the tooth forming hole 41. It can be taken out. Thereby, it is possible to prevent the helical gear 7 from being deformed, and it is possible to manufacture the helical gear 7 having excellent accuracy. Moreover, in this example, in order to rotate the die | dye 4, it is not necessary to perform special control and the structure of the gear forging apparatus 1 can be simplified.
Therefore, according to the gear forging device 1 and the gear forging method of the present example, the structure of the device is simple, the durability of the device is excellent, and the helical shaft provided with the wound tooth surface 71 on the outer peripheral surface 701. The gear 7 can be manufactured with high accuracy.

Cross-sectional explanatory drawing which shows the gear forge apparatus in the state which has arrange | positioned the raw material for gears in an Example. Cross-sectional explanatory drawing which shows the gear forge apparatus of the state which forges a gear in an Example. Cross-sectional explanatory drawing which shows the gear forge device of the state which takes out the gear in an Example. The perspective view which shows the gearwheel forged with the gear forge apparatus in an Example. The perspective view which shows the other gearwheel which can be forged with the gear forge apparatus in an Example. The perspective view which shows the other gearwheel which can be forged with the gear forge apparatus in an Example. The upper cross-section explanatory drawing which shows the engagement state of the helical groove | channel formed in the inner peripheral surface of the die case in Example, and the engagement protrusion arrange | positioned in the outer peripheral surface of die | dye. Side cross-section explanatory drawing which shows the engagement state of the helical groove | channel formed in the inner peripheral surface of the die case in Example, and the engagement protrusion arrange | positioned in the outer peripheral surface of die | dye.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gear forging apparatus 10 Forging space 11 Die base 12 Die sleeve holder 2 Punch 3 Punch holder 31 Pressing rod 4 Dies 41 Tooth mold forming hole 5 Die case 51 Gas cushion 6 Die sleeve 61 Tooth mold outer peripheral surface 7 Gear 70 Gear material 71 Vine Coiled tooth surface

Claims (7)

A device that forges helical gears from gear materials,
Punch for pressing the axial upper end surface of the gear material, a punch holder for holding the punch, a die for forming a spiral tooth surface on the outer peripheral surface of the gear material, and a die case for holding the die And a die sleeve that faces the punch and receives the lower end surface in the axial direction of the gear material, and a die base that fixes the die sleeve and the die case.
The die is rotatable with respect to the die case and the die sleeve, and has a tooth forming hole for forming the helical tooth surface.
Between the outer peripheral surface of the die and the inner peripheral surface of the die case that holds the outer peripheral surface, a spirally wound groove is formed on either side, and on the other side, the spirally wound groove is engaged. Mating engagement protrusions are formed,
The punch is configured to form a forging space for forging the helical gear together with the die forming hole of the die and the die sleeve,
In the punch holder, a push rod that pushes down the die is arranged to be movable up and down,
The die sleeve has a tooth mold outer peripheral surface along the shape of the tooth mold forming hole, and is arranged in a state where the tooth mold outer peripheral surface is engaged in the tooth mold forming hole,
The tooth surface in the tooth mold forming hole, the tooth surface on the outer peripheral surface of the tooth mold, and the spiral groove are formed on the same lead,
When the helical gear after forging is taken out from the tooth forming hole of the die, the die is pushed down by the push rod, so that the die is removed from the die case, the helical gear, and the die sleeve. The gear forging device is configured to take out the helical gear by rotating with respect to the shaft. In claim 1, the die is urged upward by urging means disposed on the die base,
The punch is configured to push down the die against the biasing force of the biasing means,
The gear forging device, wherein the push rod is configured to push down the die against the biasing force of the biasing means.   3. The gear forging device according to claim 2, wherein the urging means is a gas cushion that generates a repulsive force by utilizing a pressure of gas.   The gear forging according to any one of claims 1 to 3, wherein the engaging protrusion is provided with a roller that moves together with the engaging protrusion while rotating in the spiral groove. apparatus. In any one of Claims 1-4, the said raw material for gears has the cylinder shape provided with the shaft hole,
The gear forging device, wherein the punch has a mandrel portion that is inserted into the shaft hole of the gear material. Punch for pressing the axial upper end surface of the gear material, a punch holder for holding the punch, a die for forming a spiral tooth surface on the outer peripheral surface of the gear material, and a die case for holding the die And a gear forging device having a die sleeve that faces the punch and receives the lower end surface in the axial direction of the gear material, and a die base that fixes the die sleeve and the die case. A method of forging a helical gear,
The die is rotatable with respect to the die case and the die sleeve, and has a tooth forming hole for forming the helical tooth surface.
Between the outer peripheral surface of the die and the inner peripheral surface of the die case that holds the outer peripheral surface, a spirally wound groove is formed on either side, and on the other side, the spirally wound groove is engaged. Mating engagement protrusions are formed,
The punch is configured to form a forging space for forging the helical gear together with the die forming hole of the die and the die sleeve,
In the punch holder, a push rod that pushes down the die is arranged to be movable up and down,
The die sleeve has a tooth mold outer peripheral surface along the shape of the tooth mold forming hole, and is arranged in a state where the tooth mold outer peripheral surface is engaged in the tooth mold forming hole,
The tooth surface in the tooth mold forming hole, the tooth surface on the outer peripheral surface of the tooth mold, and the spiral groove are formed on the same lead,
The gear material is crushed by pressing the axial upper end surface of the gear material with the punch while the axial lower end surface of the gear material disposed in the forging space is received by the die sleeve. A forging step of forging the gear in the forging space,
By pushing down the die in a state where the helical gear after forging is held in the tooth forming hole by the push rod, the die is moved against the die case, the helical gear and the die sleeve. A gear forging method comprising a step of rotating and taking out the helical gear from the tooth forming hole of the die. In Claim 6, the said dice | dies are urged | biased upwards by the urging means arrange | positioned at the said die base,
In the forging step, the punch forges the helical gear while pushing down the die against the biasing force of the biasing means,
In the take-out step, the helical gear is taken out by retracting the punch from the die and further pushing down the die against the urging force of the urging means by the push rod. Gear forging method.

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