JPH01241349A - Method for forming helical gears - Google Patents

Abstract

PURPOSE:To form the helical gears having no defect simply by pushing a heated rough tooth profile blank into the outer lower die having a cutting blade and biting the tooth part of a rotating inner lower die with said cutting blade. CONSTITUTION:The rough tooth profile blank 1 heated at the shaving temp. of about 700-900 deg.C is placed on the inner lower die 4 of a lower die 6 in the forming device 3 of the helical gears whose tooth trace is nonlinear. An upper die 7 is then descended, the blank 1 is descended together with the inner lower die 4 moved in the axial direction and pushed into the outer lower die 5 which is located at fixed position. A counter pressure is applied on the inner lower die 4 having a tooth part 16 and the outer lower die 5 having a cutting edge 15 is rotated in the twisting direction relatively via a guide groove 16 and roller 47. The rough tooth profile part 2 of the blank 1 is thus subjected to shaving by the said cutting edge 15 biting with the tooth part 16.

Description

Detailed Description of the Invention A0 Object of the Invention (1) Industrial Application Field The present invention is directed to the molding of helical gears, such as helical teeth, in which tooth traces should be non-linear. Regarding the method.

(2) Conventional technology Conventionally, when manufacturing helical gears, a blank is formed by hot forging, and the blank is cut with a hob cutter, pinion cutter, etc., and if necessary, gear shaving or gear grinding is performed. A common method was to add a post-process to produce a product. However, this method is currently used only for manufacturing extremely expensive helical gears because of the long processing steps, slow production speed, and expensive production equipment.

Instead of such cutting methods, methods are now being used to manufacture helical gears by cold or hot forging, etc., but this method requires plastic flow of the entire material, so it is difficult to process. There are problems in that the force becomes extremely high, high-precision gears cannot be obtained, and the equipment becomes larger.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 129248/1982, a material was placed between a punch and a die, and the material was deformed until it broke by moving the punch and die relative to each other in a non-linear manner. A method has also been proposed in which the tooth profile is finished by a shaving blade placed at the rear of one of the strokes of the punch and die.

(3) Problems to be solved by the invention However, in the above-mentioned prior art, the breaking of the material and shaving forming are performed in one stroke of the press mold, which increases the forming load, increases wear and damage, and increases the size of the equipment. In addition, since no back pressure is applied to the material, defects such as sink marks on the tooth surface may occur.

The present invention has been made in view of the above circumstances, and provides a method for forming helical gears that enables forming gears with a small load using a simple structure and that does not cause defects. The purpose is to

B1 Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a rough method for forming helical gears having non-linear tooth traces, such as helical teeth. A rough tooth profile blank having a tooth profile on the outer periphery is axially moved by an outer lower die having a cutting blade on the inner periphery for shaving the rough tooth profile and having a ridge portion that engages with the outer lower die at a fixed position. A coarse tooth profile blank is placed in a heated state on a lower die consisting of a movable inner lower die, and is sandwiched between the upper die and the inner lower die, which can be raised and lowered above the inner lower die, to maintain a predetermined counter pressure. While applying pressure, push the coarse tooth profile blank into the outer lower die, and synchronize with the descent of the coarse tooth profile blank while guiding the relative movement of the inner lower die and outer lower die to avoid contact between the cutting edge and the teeth due to counter pressure. The first feature is that the outer lower die and the inner lower die are rotated relative to each other in the torsional direction, and the rough tooth profile is formed by shaving with the cutting blade.

In addition to the first feature, the present invention also provides a method for guiding the relative movement of the inner lower die and the outer lower die using a guide groove on one side of the inner lower die and the outer lower die and a roller on the other side that moves within the guide groove, The second feature is that the gap between the guide groove and the rollers is made smaller than the gap between the cutting blade and the teeth.

(2) Effect According to the first feature, the Matsuyama-shaped blank in a heated state is sandwiched between the inner lower die and the upper die and pushed into the outer lower die, so that it is possible to carry out Sievik forming with a relatively small load. Moreover, since a counter pressure is applied, a stable shaved surface can be obtained. Further, since the outer lower die and the inner lower die rotate relative to each other in the torsional direction in synchronization with the lowering of the Matsuyama blank, shaving of the non-linear Matsuyama shaped portion can be performed with high precision. Moreover, since the relative movement of the inner lower die and the outer lower die is guided to avoid contact between the cutting blade and the tooth portion due to the action of counter pressure, a predetermined counter pressure can be effectively applied to the Matsuyama-shaped portion.

According to the second feature, since the gap between the guide groove and the roller is smaller than the gap between the cutting blade and the teeth, the peak of the inner lower die pressed upward by the counter pressure and the cutting blade come into contact with each other. The relative movement of the inner lower die and the outer lower die can be guided by simple adjustment while avoiding such problems.

(3) Example An example of the present invention will be described below with reference to the drawings. First, in FIG. 1, for example, when forming a helical gear, a Matsuyama-shaped blank 1 is prepared by forging in a heated state. This Matsuyama-shaped blank 1 has a non-linear tooth trace, for example, a helical-shaped Matsuyama-shaped part 2a on the outer periphery, and at one end of the Matsuyama-shaped part 2 there is a paring part 2 formed during forging.
a is left over the entire circumference. The Matsuyama-shaped blank 1 has a shaving temperature of, for example, 700 to 9
It is supplied to the molding machine W3 in a state heated to 50°C, and the Matsuyama-shaped portion 2 is shaved by the molding device 3.

The molding device 3 includes a lower die 6 consisting of an inner lower die 4 and an outer lower die 5, and an inner lower die 4.
and an upper die for sandwiching the Matsuyama-shaped blank l and pushing it into the outer lower die 5, and a rotational drive mechanism 8 for rotating the outer lower die 5 in synchronization with the lowering of the upper die.

A die plate 10 is fixed on the fixed die set plate 9, and a cylindrical die holder 11 is fixed on the die plate 10. This goo holder 11 has an upper holder part 12 and a middle holder part 13 each formed in a cylindrical shape.
and the lower holder portion 14 are coaxially stacked and fixed to each other. A basically cylindrical outer lower die 5 is rotatably supported by the gouging holder 11 at a position with a gap between it and the upper surface of the die plate 10 around an axis extending vertically. In addition, on the inner surface near the upper part of the outer lower die 5,
A helical-toothed cutting blade 15 is provided for shaving the Matsuyama-shaped portion 2.

The inner lower die 4 is basically formed in a cylindrical shape, and is disposed coaxially within the outer lower die 5 so as to be movable up and down. Moreover, the upper outer surface of the inner lower die 4 has a tooth portion 1 that meshes with the cutting edge 15 of the outer lower die 5.
6 is provided. In addition, at the lower end of the inner lower die 4,
A flange portion 4a is provided that slides into contact with the inner surface of the lower holder portion 14 of the gooey holder 11. Further, the upper end surface of the inner lower die 4 is formed in a shape corresponding to the lower surface of the Matsuyama-shaped blank 1 on which the Matsuyama-shaped blank 1 is placed.

Referring also to FIGS. 2, 3, 4, and 5, an annular recess 17 is provided at the inner edge of the upper end of the outer lower die 5.
The annular recess 17 is flush with the upper end surface of the outer lower die 5 and the phase alignment guide member 1 is provided therein.
8 are fitted and fixed.

This guide member 18 is basically formed in a short cylindrical shape, and a guide tooth portion 19 corresponding to the Matsuyama-shaped portion 2 of the Matsuyama-shaped blank l is provided at the lower part of the inner surface of the guide member 18.
The cutting edge 15 is connected to the cutting edge 15.

The lower part of the knockout bin 20, which passes through the die set plate 9 and the die plate 10 in a vertically movable manner, is connected to a driving means such as a cylinder (not shown), and the knockout bin 20 extends vertically at the center of the inner lower die 4. Matsuyama-shaped blank 1 ascends inside the drilled through hole 4b.
It can come into contact with the bottom surface of. Further, in the lower part of the outer lower die 5, cylinders 21 having axes extending in the vertical direction are buried and arranged at multiple locations with equal intervals in the circumferential direction. It extends downward and comes into contact with the upper surface of the lower end flange 4a of the inner lower die 4.

In the upper part of the die plate 10, cylinders 23 having vertically extending axes are embedded and arranged at multiple positions in the circumferential direction surrounding the knockout bin 20, and the piston rods 24 of these cylinders 23 are connected to the inner lower die 4. It touches the bottom surface. Moreover, each cylinder 23 is arranged such that in the original position where the Matsuyama-shaped blank 1 is placed on the inner lower die 4, the upper edge of the inner lower die 4 is located slightly below the upper inner edge of the outer lower die 5. When the inner lower die 4 is lowered from the original position shown in FIG. It exerts an upward rebound force to apply counter pressure to the surface.

The upper die is basically formed in a cylindrical shape with a lower surface corresponding to the upper surface of the Matsuyama-shaped blank 1, and is fixed to a movable die plate 25 that can be raised and lowered by being connected to a lifting drive means (not shown). It is held in a holder 26 allowing relative movement within a limited range. A tooth portion 27 having a tooth trace extending in the axial direction is provided on the outer surface of the upper diamond.

A ring-shaped stripper 28 surrounding the upper diameter is suspended from the holder 26 . That is, the base ends of a plurality of rods 29 extending vertically are fixed to the stripper 28, and a regulating collar 30 provided at the upper end of these rods 29 extends vertically and closes both ends and is provided in the holder 26. It is slidably fitted into the holding hole 31 . Moreover, a spring 32 or a hydraulic cylinder is interposed between the upper closed end of the holding hole 31 and the regulating collar 30, and the stripper 28 is elastically urged downward by the repulsive force of the spring 32 or the hydraulic cylinder. be done.

Therefore, the stripper 28 is elastically biased downward and is movable vertically relative to the upper diamond within a controlled range.

A protrusion 28a that protrudes downward is provided at the lower inner edge of the stripper 28, and the lower end of this protrusion 28a is connected to the upper end surface of the Matsuyama-shaped portion 2 of the Matsuyama-shaped blank 1 placed on the inner lower die 4. It is possible to come into contact with. Furthermore, the inner surface of the stripper 28 is provided with teeth 33 that mesh with the teeth 27 of the upper diamond.

The rotational drive mechanism 8 is for rotating the outer lower die 5 around its axis in response to the lifting and lowering operations of the upper die, and includes a screw shaft 35 having an axis extending vertically and connected to the upper die, and a screw shaft 35 connected to the upper die. It includes a drive gear 36 that is screwed onto the screw shaft 35 and a driven gear 37 that meshes with the drive gear 36.

A sleeve 38 extending in the vertical direction is fixed to the upper holder part 12 of the die holder 11, and a sleeve 39 is fixed to the lower holder part 14 coaxially with the sleeve 38.

The drive gear 36 is rotatably supported around the axis between the sleeves 38 and 39. Also screw shaft 3
5 passes through both sleeves 38 and 39 so as to be axially movable, and a threaded portion 35 a carved on the outer surface of the intermediate portion of the screw shaft 35 is screwed into the inner surface of the drive gear 36 .

Further, the driven gear 37 is carved on the outer surface of the outer lower die 5, and this driven gear 37 is connected to the drive gear 3.
6 is engaged. Therefore, the drive gear 3G is rotationally driven in accordance with the axial movement of the screw shaft 35,
Further, the driven gear 37, that is, the outer lower die 5 is driven for angular displacement.

Further, a retaining portion 35b having a non-circular cross section is provided at the lower part of the screw shaft 35.
5b is the lower holder portion 14 so as to prevent rotational operation.
It movably penetrates a locking member 4o disposed in the. This prevents the screw shaft 35 from rotating. The lower end of the screw shaft 35 is in contact with the upper end of a piston rod 42 in a cylinder 41 which extends vertically and is fixedly arranged on the TEGIF plate 10, and by extending the cylinder 41, the screw shaft 35 is moved upward.

A connecting rod 43 is coaxially connected to the upper end of the screw shaft 35. A flange portion 43a is provided at the upper end of this connecting rod 43, and this flange portion 43a is formed between a holding member 44 fixed to the lower surface of the movable die plate 25 and the movable die plate 25 within a limited range. It is maintained by allowing vertical relative movement. As a result, the screw shaft 35 becomes an amber diamond, that is, the movable goo plate 25
It goes up and down according to the up and down operation of.

Furthermore, in order to apply the same pressure to the back surface of the connecting rod 43 and the back surface of the upper dia, a passage 45 is provided in the movable gouer plate 25 to connect the space facing the back surfaces thereof.

In FIG. 6, on the inner surface of the outer lower die 5, guide grooves 46 having an inclination angle α corresponding to the incisors 15 are bored at a plurality of locations in the circumferential direction. A roller 47 for transferring is pivotally supported. Moreover, the gap between the guide groove 46 and the roller 47 (for example, 0
．． 03 to 0.06 mm) is smaller than the gap between the incisors 15 and the tooth portions 16 (for example, 0.1 to 0.5 mm).

Next, the processing procedure of the Matsuyama-shaped blank 1 by the forming device 3 will be explained. First, the Matsuyama-shaped blank 1 heated to 700 to 950°C is shaped into the Matsuyama-shaped part 2 by the guide teeth 19 of the guide member 18. It is placed on the lower die 6 so that the phase matches the cutting edge 15 of the outer lower die 5.

Next, when the movable gouly plate 25 is lowered, the Matsuyama-shaped blank 1 is held between the inner lower die 4 and the upper die of the lower die 6, as shown in FIG. When the movable gouly plate 25 is further lowered in this state, the Matsuyama-shaped blank 1 is pushed into the outer lower die 5 while being held between the inner lower die 4 and the upper die.

Moreover, since the screw shaft 35 also descends as the movable guide punch 25 and the upper die descend, the outer lower die 5 is rotationally driven in synchronization with the descent of the Matsuyama-shaped blank 1 by the action of the rotational drive mechanism 8. Therefore, the outer lower die 5 and the inner lower die 4 rotate relative to each other in the torsional direction in synchronization with the descent of the Matsuyama-shaped blank 1, and this relative rotational movement allows the cutting blade 15 to shave the coarse tooth profile 2. .

During this shaving process, a shaving load (tensile stress) is applied to the rough tooth profile portion 2 by the cutting blade 15. If such a load remains applied only in a certain direction, the resistance of the cutting edge 15 will cause chattering and sink marks on the tooth tip, as well as cracks due to secondary shearing, etc., will occur in the coarse tooth profile portion 2 due to the resistance of the cutting edge 15. Even during knockout, the product does not come off smoothly from the cutting edge 15, resulting in the same defects as described above.

However, counter pressure from the plurality of cylinders 23 acts on the inner lower die 4 when it is lowered. Moreover,
Since the gap between the guide groove 46 and the roller 47 is smaller than the gap between the cutting edge 15 and the crest 16, the cutting edge 15 and the teeth 16 mesh as shown in FIG. 7(a). The roller 47 contacts the side surface of the guide groove 46 before the cutting edge 1
5 and the tooth section 16 is maintained, counter pressure can be prevented from acting on the cutting edge 15, and the counter pressure can be reliably applied to the coarse tooth section 2.
By rolling along the guide groove 46, the outer lower die 5 can be smoothly rotated in synchronization with the descent of the Matsuyama-shaped blank 1. As a result, the shaving load and the compressive load due to the counter pressure acting against the shaving load act on the rough tooth profile part 2, and the shaving process of the coarse tooth profile part 2 is carried out in a constant balance between tension and compressive stress. It will be done. On the other hand, if the roller 47 and the guide groove 46 are not provided, the teeth 16 of the inner lower die 4 will come into contact with the cutting edge 15 as shown in FIG. 7(b) when certain molding conditions are exceeded. However, since the counter pressure is prevented from effectively acting on the coarse tooth profile portion 2, a good shaving surface cannot be obtained.

Moreover, when the Matsuyama-shaped blank 1 is pressed down by the upper diamond, the protrusion 28a at the lower end of the stripper 2 comes into contact with the upper end surface of the rough tooth profile part 2, as shown in FIG. It works effectively. Furthermore, the stripper 28 applies back pressure to the coarse tooth profile 2 due to the compression of the spring 32 in response to the downward relative movement of the holder 26 with respect to the stripper 28 . Therefore, a counter pressure and a counter pressure acting against the counter pressure act on the rough tooth profile portion 2, which increases the internal pressure of the rough tooth profile portion 2, which prevents defects such as chatter, sink marks, and droop during shaving. This can be reliably prevented.

When the inner lower die 4 descends to the lowest limit, the shaving process of the rough tooth profile part 2 is completed, but at this time, the shaving residue part 2b generated by shaving is removed from the paris part 2a.
The shaving portion 2a and the shaving oscillating portion 2b remain in a half-opened state just before they are completely separated from the formed end face of the coarse tooth profile portion 2, and the shaving portion 2a and the shaving oscillating portion 2b are dispersed in the forming device 3. After that, the upper diameter is raised, and at this time, the cylinder 41 is extended and the screw shaft 35 is raised.
Accordingly, the outer lower die 5 rotates in the opposite direction to that during processing, and the inner lower die 4 thereby rises. Then, the Matsuyama-shaped blank l which has been shaved with the knockout pin 20 is removed from the lower die 6, and the bulge portion produced by the shaping process is cut off to obtain a product.

The relationship between the amount of sinkage on the tooth surface and the counter pressure is shown in FIG. 8. If the allowable amount of sinkage is 2 mm, the counter pressure must be 3 kg/mm'' or more. Figure 9 shows the relationship between shaving temperature and formability. Figure 9 shows the relationship between shaving amount and shaving temperature. When the allowable sagging amount is 1 mm, the shaving temperature is 950°
C or lower is required. In addition, if the shaving temperature is less than 700°C, the workpiece will crack during processing, so the shaving temperature will be 700 to 9506°C.
will be required to be.

Next, a specific example of forming a helical gear according to the present invention will be shown.

The material is SCM420.5Cr420 and the diameter is 77m.
Matsuyama-shaped blank with mΦ was heated to 1000 To
It is forged and formed using an n-press. Then 700-950'
Shaving from 0 to 0.6 mm in the heating state of c.
, under the conditions that the shaving speed was 90 to 250 mm/sec, the shaving load was 60 to 140 Tons, and the counter pressure was 3 to 8 kg/mm2, the tip circle diameter was 76 mm.
An involute helical gear of module 2.5 with mmΦ, number of teeth of 27 to 29, and helix angle of 36 degrees was molded.

At this time, if the circumferential surface roughness of the tooth portion is R1 and the axial roughness is R2, No. 61 and No.

The product accuracy of No. 2 is as shown in the table below with respect to the target value corresponding to DIN grade 9.

As can be seen from this result, even if a helical gear is formed according to the present invention, a gear with sufficiently high precision can be obtained.

C1 Effects of the Invention As described above, according to the first feature of the present invention, when molding helical gears such as helical gears in which tooth traces are non-linear, An outer lower die having a cutting blade on the inner periphery for forming the pine-shaped blank by shaving and forming the pine-shaped portion is fixed at a fixed position, and an inner lower die having teeth that mesh with the cutting blade and movable in the axial direction. A Matsuyama-shaped blank is placed on a lower die in a heated state R, and the Matsuyama-shaped blank is sandwiched between an upper die that can be raised and lowered above the inner lower die, and an inner lower die, and a predetermined counter pressure is applied to the Matsuyama-shaped blank. is pushed into the outer lower die, and the outer lower die and inner lower die are rotated relative to each other in the torsional direction in synchronization with the descent of the Matsuyama-shaped blank, and the Matsuyama-shaped part is shaved with the cutting blade, making the configuration relatively simple and reducing the load. It is possible to perform shaving molding in a relatively small size, contributing to the miniaturization of the molding equipment, and the relative rotation of the outer and inner lower dies in the torsional direction allows shaving of non-linear Matsuyama-shaped parts to be performed with high precision. be able to.

Further, during shaving, a compressive load due to a predetermined counter pressure is applied to the Matsuyama-shaped portion in opposition to the shaving load, so shaving can be performed while balancing the load, and the precision of the product can be improved. Furthermore, since the relative movement of the inner lower die and outer lower die is guided to avoid contact between the cutting edge and the teeth due to the action of counter pressure, the counter pressure is reliably applied to the Matsuyama-shaped part to prevent defects as much as possible. It can be prevented.

According to the second feature, the relative movement of the inner lower die and the outer lower die is guided by the guide groove on one side of the inner lower die and the outer lower die and the roller on the other side that moves within the guide groove, and the guide groove and the roller Since the gap between the two is made smaller than the gap between the cutting edge and the teeth, it is possible to guide the relative movement of the inner lower die and outer lower die with simple adjustment while avoiding contact between the cutting edge and the teeth. .

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view of a molding device taken along line I-1 in FIG. 2, and FIG. 2 is a cross-sectional view taken along line ■-■ in FIG. 3 is an enlarged view of part ■ in FIG. 1, FIG. 4 is a sectional view corresponding to FIG. 3 at the end of molding, FIG. 5 is a sectional view taken along the line ■-V in FIG. The figure is a sectional view taken along the line VI-VI in Fig. 1, Fig. 7 is a longitudinal sectional view of the cutting edge portion showing the state of action of counter pressure on the Matsuyama-shaped portion, and Fig. 8 is a sectional view of the counter pressure and the sinkage of the tooth surface. FIG. 9 is a graph showing the relationship between shaving temperature and shaving amount.

Claims (2)

[Claims] (1) When forming helical gears such as helical gears with non-linear tooth traces, a rough tooth profile blank having a rough tooth profile on the outer periphery is used with a cutting blade for shaving the rough tooth profile. The inner lower die is placed in a heated state on a lower die consisting of an outer lower die located at a fixed position on the inner periphery and an inner lower die having teeth that engage with the cutting blade and movable in the axial direction. A coarse tooth profile blank is sandwiched between an upper die that can be raised and lowered above and an inner lower die, and the coarse tooth profile blank is pushed into the outer lower die while applying a predetermined counter pressure. While guiding the relative movement of the inner lower die and outer lower die to avoid contact between the parts, the outer lower die and inner lower die are rotated relative to each other in the torsional direction in synchronization with the lowering of the coarse tooth profile blank, and the coarse tooth profile part is shaved with the cutting blade. A method for forming helical gears characterized by forming them. (2) Guide grooves on one side of the inner lower die and outer lower die and rollers on the other side rolling in the guide grooves guide the relative movement of the inner lower die and outer lower die, and cut the gap between the guide groove and the rollers. The first (first) characterized in that the gap is smaller than the gap between the blade and the teeth.
Method for forming helical gears described in ).