JPH08323443A - Production of helical gear - Google Patents

Abstract

PURPOSE: To improve durability of a forging die and a form rolling tool by forming a columnar stock into a cylinder shape, executing intermediate annealing, forging to a preliminary helical gear, cutting the end part for a prescribed length, and finishing to a finished helical gear with tooth form rolling. CONSTITUTION: In a first process, a columnar stock W1 is formed into a cylindrical stock W2 by preliminary forging. In a second process, by executing intermediate annealing, an annealed material W3 is obtained. in a third process, a preliminary helical teeth 7 are forged on the outer periphery of annealed material W3 so as to form a rough gear W4. In a fourth process, the end of the rough gear W4 is cut, the length in the axial direction is made a prescribed length so as to form an intermediate gear W5. In a fifth process, the preliminary helical teeth 7a of the intermediate gear W5 is subjected to tooth form rolling so as to be finished to a desired finish helical teeth 8. By this method, the working is split into five processes and executed, the loads applied to a die and a tool are reduced and life of the die and the tool is extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a helical gear in which helical teeth are formed on the outer circumference.

[0002]

2. Description of the Related Art Conventionally, as a method for manufacturing a helical gear in which tooth lines are formed in a helical winding shape, a cylindrical material previously formed into a cylindrical shape by pre-forging is used by mesh cutting of a worm mechanism. Preliminary helical teeth are formed on the outer circumference by a hobbing machine, and then a preliminary shaving tooth is further ground by a gear shaving machine using mesh cutting of a pair of gears to manufacture a helical gear with highly accurate finishing helical teeth. Was there.

[0003]

When the helical gear is manufactured by using the hobbing machine and the gear shaving machine as described above, high accuracy can be obtained. However, the hobbing machine and the gear shaving machine have low durability because the helical gear is formed by cutting, and it is necessary to frequently replace the blade, which may increase the processing cost. Further, in the gear shaving machine, the blade edge of the gear blade is worn by use, but since the gear blade is expensive, the blade edge of the gear blade is re-polished and reused. However, the precision of the cutting edge of the re-grinded gear blade may be non-uniform and the precision may decrease.

Therefore, in recent years, forging of helical gears has been performed. There are many methods for forging the helical gear, such as Japanese Patent Laid-Open No. 3-57527 and Japanese Patent Publication No. 6-85971.

However, even if the helical gear is forged as described above, it is difficult to obtain high accuracy, and therefore, after the forging, it is necessary to further perform forging sizing. However, since the helical gear is formed in a helical winding shape, it is difficult to improve the sizing accuracy as compared with the case of performing forging sizing with a spur gear.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems, to provide a method for manufacturing a helical gear which suppresses the processing cost and molds a highly accurate helical gear.

[0007]

The present invention is as follows.

A first step of forming a cylindrical material into a cylindrical shape by continuous pre-forging, a second step of subjecting the cylindrical material to an intermediate annealing, and a preliminary helical tooth on the outer periphery of the annealed material after the intermediate annealing. The third step of forging, the fourth step of cutting at least one end of the rough gear forged with the preliminary helical teeth to make the axial length to a desired length, and the preliminary helical teeth of the cut intermediate gear. And a fifth step for finishing the desired finished helical tooth by rolling the tooth profile.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a process of manufacturing a helical gear according to an embodiment of the present invention and a molding state of a product at that time. First, a columnar material W1 obtained by cutting a linear material in advance is subjected to continuous pre-forging. A cylindrical material W2 having a cylindrical shape is formed.

This pre-forging step will be described with reference to FIG. 2. A cylindrical material W1 is subjected to an axial load to slightly increase the outer diameter and has a curved corner portion 1 at one end.
11 is formed, and then the outer diameter of the sink material W11 is further expanded, and a uni-concave material W12 having a slightly recessed taper recess 2 on the end face on the side of the bent corner 1 is formed. Then, a biconcave material W13 in which a preliminary concave portion 4 is provided continuously to the tapered concave portion 2 formed at one end of the one-side concave material W12 toward the other end and an inverse taper concave portion 3 equivalent to the tapered concave portion 2 is provided at the other end. To mold. A pre-walled portion 5 is formed between the reverse taper concave portion 3 and the preliminary concave portion 4 of the biconcave material W13.

The process of forming the biconcave material W13 from the one-concave material W12 will be described with reference to FIG.

FIG. 3 shows an extrusion forging device 30, in which the left half shows the state before forming and the right half shows the state after forming. A fixed die 41 has a fixed die 4 having a through hole 42a extending in the axial direction.
2 and a fixed holder 46 for holding the fixed die 42, and a fixing pin 45 having the same diameter as the preliminary recess 4 of the biconcave material W13 is arranged in the through hole 42a.
A ring knockout 44 that is slidable in the axial direction is arranged between the ring knockout 44 and 2a. And the through hole 42a of the fixed die 42
By the above, the fixing pin 45 and the one end of the ring knockout 44 form the mold engraving space 43 into which the single concave material W12 is inserted. The ring knockout 44 is slid in the axial direction by a backup ring 47 that comes into contact with the end portion on the side opposite to the engraving space. Further, 31 is a slide type and a fixed type 41
The punch 32 and the punch 32 are opposed to the mold engraving space 43 of
Is provided with a pressing ring 33 for slidably holding it in the axial direction, and the punch 32 has a backup pin 35 so that the end of the punch on the fixed die side protrudes from the end of the pressing ring 33 in a natural state.
Is always pressed by the fixed mold side. A slide holder 34 is arranged on the outer peripheral side of the pressing ring 33.

When the bi-concave material W13 is formed from the uni-concave material W12 by the extrusion forging device 30, the uni-concave material W12 is made so that the tapered recess 2 contacts the fixing pin 45, as shown in the left half of FIG. The fixed die 41 is put into the engraving space 43, and then the slide die 31 is moved forward. Then, at the same time when the punch 32 of the slide die 31 comes into contact with the one-sided concave material W12, the punch 32 is accommodated in the pressing ring 33 leaving the tip end, and forging is started. That is, as shown in the right half of FIG. 3, the preliminary recess 4 is formed at one end of the taper recess side by the forward extrusion by the fixing pin 45, and the punch 32 is formed at the other end.
The reverse taper recess 3 is formed by. After that, the slide die 31 is retracted, the ring knockout 44 is projected, and the formed biconcave material W13 is taken out from the fixed die 41, and this step is completed.

Then, as shown in FIG. 2, the preform portion 5 of the biconcave material W13 is removed to form a cylindrical material W2. This step will be described with reference to FIG.

FIG. 4 shows the piercing device 50. The left half shows the state before molding and the right half shows the state after molding. 61 is a fixed type,
Fixed die 62 having a through hole 62a extending in the axial direction
And a fixed holder 66 for holding the fixed die 62,
A fixing pin 65 having the same diameter as the inner peripheral through hole 6 of the cylindrical material W2 is arranged in the through hole 62a.
Ring knockout 6 that can slide axially with a
4 are arranged. The through hole 62a of the fixed die 62
With the fixing pin 65 and the one end of the ring knockout 64, a die engraving space 63 into which the one-sided concave material W12 is inserted is formed. The ring knockout 64 is slid in the axial direction by a backup ring 67 that comes into contact with the end of the ring knockout 64 on the side opposite to the die-sinking space. Further, 51 is a slide type and a fixed type 61
Of the pressing ring 52, the outer diameter of which is the same as the inner diameter of the through hole 62a of the fixed die 62 and the inner diameter of the ring opening 52a which is formed inside the end is the same as the outer diameter of the fixing pin 65.
And the slide holder 5 is provided on the outer peripheral side of the pressing ring 52.
3 and the guide ring 54 are integrally fixed. Further, a backup die 55 is arranged at the end of the pressing ring 52 opposite to the ring opening side. Further, inside the pressing ring 52, the backup die 55, the slide holder 53 and the guide ring 54, a surplus discharge hole 56 is formed which is continuous from the ring opening 52a to the outside of the slide die 51.

When the cylindrical material W2 is formed from the biconcave material W13 by the piercing device 50, as shown in the left half of FIG. 4, the biconcave material W13 is fixed so that the preliminary recess 4 is engaged with the fixing pin 65. The mold 61 is put into the mold engraving space 63, and then the slide mold 51 is moved forward. Then, as shown in the right half of FIG. 4, the pressing ring 52 of the slide die 51 abuts on the biconcave material W13 and at the same time, pushes it forward to punch out the preformed portion 5 of the biconcave material W13 with the fixing pin 65. At this time, the blank portion 5 punched out is discharged into the excess thickness discharge hole 56 of the slide die 51. After that, the slide die 51 is retracted, the ring knockout 64 is projected, and the formed cylindrical material W2 is taken out from the fixed die 61, and this step is completed.

Next, as shown in FIG. 1, the cylindrical material W2 is subjected to intermediate annealing to form an annealed material W3. In this intermediate annealing, the cylindrical material W2 is put into a furnace heated to about 600 ° C., heated for a predetermined time and then cooled to form an annealed material W3.
Thereby, the internal stress is removed by the preliminary forging.

Subsequently, the preliminary helical teeth 7 are forged on the outer periphery of the annealed material W3 to form the rough gear W4. This step will be described with reference to FIG.

FIG. 5 shows a tooth profile forging device 70, in which the left half shows the state before forming and the right half shows the state after forming. Reference numeral 81 denotes a fixed die, which includes a die holder 83 that defines a die engraving space 84 into which the annealed material W3 is charged, a fixed die 82 that has forming teeth 82a continuous to the die engraving space 84 on its inner circumference, and a formed rough gear W4. It is composed of a base 85 having a discharge space 86 for discharging. Further, 71 is a slide type, and is provided with a punch 72 and a pressing ring 73 that slidably holds the punch 72 in the axial direction, facing the die engraving space 84 of the fixed die 81. The portion naturally projects from the end of the pressing ring 73. The slide holder 7 is provided on the outer peripheral side of the pressing ring 73.
4 and the guide ring 75 are arranged, and the guide ring 75
The female screw portion 76a of the assembling member 76 is screwed into the male screw portion 75a formed on the outer periphery of the above to be integrally assembled.

When the rough gear W4 is formed from the annealed material W3 by the tooth profile forging device 70, the annealed material W3 is put into the die engraving space 84 of the fixed die 81 as shown in the left half of FIG. The forming teeth 82a of the fixed die 82 include the half-forming gears W3a and W3b during the forming of the preliminary helical teeth 7. In this state, the slide die 71 is moved forward. Then, as shown in the right half of FIG. 5, after the punch 72 of the slide die 71 is fitted into the inner peripheral through hole 6a of the annealed material W3, the annealed material W3 is fixed by the pressing ring 73 which is fitted into the die engraving space 84. The preliminary helical teeth 7 are pressed into the forming teeth 82a of the die 82 and the forming of the preliminary helical teeth 7 is performed halfway. Then, of the half-molded gears W3a and W3b pressed by the annealed material W3, the half-molded gear W3a on the base 85 side is extruded to form the rough gear W4 as the base 85.
The discharge space 86 is discharged to complete this process.

Then, as shown in FIG. 1, the rough gear W4 is raced to form an intermediate gear W5. In this race processing, one end or both ends of the rough gear W4 is cut by mechanical cutting, and thereby the axial length is made a desired length.

Finally, the preliminary helical teeth 7a of the intermediate gear W5 are subjected to tooth profile rolling to form the helical gear W6. This step will be described with reference to FIG.

FIG. 6 shows a rolling device 90, and 91 and 91 are rolling tools. The rolling tools 91, 91 include rolling teeth 92, 92 for forming the finishing helical teeth 8 and the rolling tool 9
It is composed of rolling shafts 93, 93 for rotating 1, 91, and the rolling tools 91, 91 are movable in directions perpendicular to the rolling shafts 93, 93 in mutually opposite directions. In addition, the rolling tool 91,
A pair of upper and lower support members 94 for holding the intermediate gear W5 are arranged at the centers of the rolling teeth 92 of the 91 facing each other. This support tool 94 is rotatable in the direction opposite to the direction of rotation of the rolling shafts 93, 93 of the rolling tools 91, 91.

When forming the helical gear W6 from the intermediate gear W5 by the rolling device 90, the rolling tools 91, 91 are previously prepared.
With the stand-by at the initial position away from the support 94,
The intermediate gear W5 is supported between the pair of support members 94. Subsequently, the rolling tools 91, 91 are rotated in the same direction, and the support tool 94 is rotated in the opposite direction of the rotation direction of the rolling tools 91, 91, so that the rolling tools 91, 91 are continuously moved to the intermediate gear W5. Approach. After the rolling tools 91, 91 come into contact with the intermediate gear W5, they are further pressed and pinched to finish the helical teeth 8
Is molded. After that, the rolling tools 91, 91 are retracted to the initial positions, the support tool 94 is opened, the molded helical gear W6 is removed from the rolling device 90, and this step is completed.

Therefore, the helical gear W is processed in the above-described process.
When 6 is rolled, the load applied to the forging die and the rolling tool can be suppressed.

In the above embodiment, the process of sequentially manufacturing the helical gear W6 has been described, but it goes without saying that processing such as oil holes and grooves may be added.

[0028]

As described above, according to the present invention, the first step of forming a cylindrical material into a cylindrical shape by continuous pre-forging, the second step of subjecting the cylindrical material to intermediate annealing, and the intermediate step The third step of forging the preliminary helical teeth on the outer circumference of the annealed material after annealing, and cutting at least one end of the rough gear forged with the preliminary helical teeth to make the axial length a desired length. As it consists of the process and the fifth process of finishing the cut helical gear teeth of the intermediate gear into desired finishing helical teeth by tooth profile rolling, the load applied to the forging die and rolling tool can be suppressed and durability Can be improved, and a decrease in the accuracy of the helical gear can be suppressed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a process of manufacturing a helical gear according to an embodiment of the present invention and a molding state of a product at that time.

FIG. 2 is an explanatory view of forming a cylindrical material from a cylindrical material according to an embodiment of the present invention.

FIG. 3 is a partial cross-sectional plan view showing a process of forming a double-concave material from a single-concave material according to an embodiment of the present invention, in which a left half portion shows a state before forming and a right half portion shows a state after forming.

FIG. 4 is a partial cross-sectional plan view showing a step of forming a cylindrical material from a biconcave material according to an embodiment of the present invention, in which the left half portion shows a state before forming and the right half portion shows a state after forming.

FIG. 5 is a partial cross-sectional plan view showing a step of forming a rough gear from an annealed material according to an embodiment of the present invention, in which a left half portion shows a state before forming and a right half portion shows a state after forming.

FIG. 6 is a side view of essential parts showing a step of forming a helical gear from an intermediate gear according to the embodiment of the present invention.

[Explanation of symbols]

 7 Spare Helical Teeth 7a Spare Helical Teeth 8 Finishing Helical Teeth W1 Cylindrical Material W2 Cylindrical Material W3 Annealing Material W4 Rough Gear W5 Intermediate Gear

Claims (1)

[Claims] 1. A first step of forming a cylindrical material (W1) into a cylindrical shape by continuous pre-forging, a second step of subjecting the cylindrical material (W2) to an intermediate annealing, and a step after the intermediate annealing. The third step of forging the preliminary helical teeth (7) on the outer periphery of the annealed material (W3), and cutting at least one end of the rough gear (W4) forged by the preliminary helical teeth (7) to obtain the axial length. To a desired length, and a fifth step of finishing the cut helical gear teeth (7a) of the intermediate gear (W5) into desired finishing helical teeth (8) by tooth profile rolling. A method for manufacturing a characteristic helical gear.