JP2885266B2 - Forming method for sheet metal tooth profile parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a case in which a toothed part made of a sheet metal, for example, a part such as a drive plate and a ring gear in an automatic transmission for an automobile is formed as an integrated part from a thin sheet metal material. The present invention relates to a method for forming a sheet-metal tooth profile part.

[0002] In particular, the present invention relates to a method for forming a sheet metal tooth-shaped part, which enables a process from a punching process of a sheet metal material to a tooth forming shape to be performed by a series of presses (transfer press or the like).

[0003]

2. Description of the Related Art Conventionally, for example, a ring gear in an automatic transmission for an automobile is generally integrated with a ring gear and a drive plate which are separately processed by welding or the like. In the conventional structure shown in FIG. 13, the ring gear 1 and the drive plate 2 are manufactured separately, and the ring gear 1 is welded to the torque converter 3. In addition, there is also a structure in which the ring gear 1 is welded directly to the outer peripheral side of the drive plate 2 to be integrated (not shown). However, such a manufacturing method requires many man-hours, and furthermore, it is difficult to secure the accuracy at the time of welding and assembling.

[0004] In order to solve this problem, a technique is conceivable in which the ring gear 1 and the drive plate 2 are integrally formed from the same material, that is, a sheet metal material. That is, as shown in FIG. 10, the outer peripheral end of the drive plate 2 is bent substantially vertically to provide the side wall 2a, and the tooth profile of the ring gear 1 is formed on the side wall 2a. With respect to such a tooth forming shape of the ring gear 1, drawing forming or rolling forming by pressing may be considered. However, if forming is performed so as to secure the shape and accuracy of the tooth shape, a large pressure of the press machine causes the material thickness to be reduced to 30%. ６０60% of the thickness is reduced. That is,
If the thickness of the drive plate 2 is set with emphasis on the strength of the teeth, the thickness of the drive plate 2 becomes unnecessarily large. Conversely, if the thickness of the drive plate 2 is set to the required thickness, In addition, the thickness of the tooth portion is reduced, and the ring gear 1 cannot have sufficient strength.

In order to increase only the thickness of the teeth of the ring gear 1 without increasing the thickness of the drive plate 2, it is necessary to increase the thickness of the side wall 2a of the drive plate 2. . As a method for increasing the thickness of the side wall portion 2a, there is, for example, rolling as disclosed in JP-A-4-37432 or forging (press) as disclosed, for example, in JP-A-4-9243.

[0006] There is also a cold forging (disposal hole processing) method of a gear in which a hole is formed in a separate step after preforming the tooth profile to form a relief area for the material, thereby avoiding hermetic forging. However, this method is applied when forming a spur gear or the like from a thick plate material having a tooth thickness or more, and cannot be adopted when forming a gear part from a sheet metal material.

[0007]

By the way, the above-mentioned thickening and tooth forming by rolling are low in productivity due to a long cycle time, and require a special machine. For this reason, it is disadvantageous in terms of the configuration of the production line and the product cost as compared with the case where the steps from the punching of the sheet metal material to the tooth formation are performed by pressing.

On the other hand, in the case of the forging (press) method described above, the thin plate is forged in a wide area when the wall thickness is increased, and the forging portion is in a flat plate compression state, so that the forming load is significantly increased. Therefore, it is necessary to add a step having an extremely large forming load between the step of punching the sheet metal material and the step of forming the teeth, which makes it difficult to increase the wall thickness or performs a series of steps in a highly productive transfer. There is an inconvenience that it is difficult to perform continuous molding with a press.

In view of the above, the present invention has been made in view of the above-mentioned problems, and can mass-produce high-precision, low-cost tooth-shaped parts from a sheet metal material without requiring a dedicated machine or a special press process. An object of the present invention is to provide a method for forming a sheet metal tooth profile part.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and a first aspect of the present invention is a method for forming a toothed part made of sheet metal by forging a sheet metal material to form a toothed part. The sheet metal which is drawn to form a tooth forming position
A drawing step of providing a flat-plate cylindrical side wall portion in the peripheral portion of the material body; and positively buckling the side wall portion in a state where the inner peripheral surface side of the tooth forming surface is restrained at the time of forging.
And a buckling thickening step of forging the upper end of the slab to increase the thickness of the desired side profile on the side wall portion . In this case, the relationship between the thickness t of the sheet metal material and the height h ₀ of the side wall portion is h
_The drawing process may be performed so that ₀ / t ≧ 2.

[0011] A second aspect of the present invention is to forge a sheet metal material.
Method of forming sheet metal tooth profile parts
And draw the sheet metal material body in advance to the tooth forming position.
A drawing step of providing a wall, and
Preliminary tooth formation to control material movement during forging by shaping the teeth
In the forming process, with the back side of the tooth forming surface restrained during forging
Positively buckle the side wall portion to form a desired tooth profile on the side wall portion.
Buckling thickening process to increase the thickness of the shape
A method for forming a sheet-metal tooth-shaped part, characterized in that: In this case, the small-diameter portion diameter of the die to be used inside the large diameter D _y and the preliminary tooth forming of the sidewall portion after being pre-tooth shaped d _d
Relationship with may be set such that D _y ≧ _d d.

Further, a third aspect of the present invention is that, after the buckling thickening step is performed, a working method such as ironing, rolling (plastic working), and hobbing (cutting) is performed.
The present invention is characterized in that a tooth profile finishing process for forming a tooth profile with desired dimensional accuracy and removing sink marks generated on tooth surfaces is provided.

A preliminary tooth forming step is provided before the buckling thickening step, and a tooth finishing step is provided after the buckling thickening step, so that the tooth profile is processed through four stages including a drawing step. Molding may be performed. Then, these series of press forming steps may be performed by a transfer press having high productivity, and without using a large-sized transfer press, each press step is performed by a single press or a single press is arranged. It may be performed by a tandem press.

[0014]

According to the first means of the present invention described above, buckling occurs near the center of the side wall portion subjected to forging, and the member and the seat that restrain the inner peripheral surface side of the tooth forming surface of the side wall portion. An air gap is formed between the bent side walls. Then, the forged sidewall material flows to the die side where the tooth profile is formed, and conforms to the die shape to increase the thickness of the desired tooth profile. The formation of the above-mentioned voids makes it possible to secure a relief area for the material, thereby avoiding forging and forging. Therefore, the necessary tooth profile can be obtained without increasing the forging load.

Next, according to the second means of the present invention, before the buckling thickening step is performed, the side wall portion is formed with the preliminary teeth, so that the material movement amount at the time of forging is within a predetermined range. Be able to control. This makes it possible to suppress the sink phenomenon that easily occurs in the appearance of the small-diameter corner portion (concave shape portion) of the tooth profile at the time of forging the tooth profile in which the material movement amount is large.

Further, according to the third means of the present invention, after the buckling thickening step is performed, the tooth profile finishing step such as ironing is performed, so that the diameter of the tooth surface can be reduced in one step. It is possible to remove sink marks generated in the corner portion (concave shape portion) appearance and improve the accuracy of the tooth profile.

[0017]

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

FIG. 10 shows a ring gear 1 in an automatic transmission for an automobile as an example of a sheet metal tooth-shaped part manufactured by the method of the present invention. The ring gear 1 is a drive plate 2 formed of a sheet metal material. It is formed integrally with the outer peripheral end. The ring gear 1 is formed by forming a tooth profile by forging (pressing) on an outer peripheral surface of a side wall 2a obtained by bending an outer peripheral end of a drive plate 2 substantially vertically. In the figure, reference numeral 3 denotes a torque converter.

In order to press-mold a drive plate integrated with the above-described ring gear, a series of steps as schematically shown in FIG. 11 can be considered. That is, a blanking process of punching a flat plate (blank) 4 having a required shape from a thin sheet metal material, and a deep drawing of the flat plate 4 to form a side wall 2a.
(The shape of the drive plate 2 may be formed simultaneously if necessary) and the side wall portion 2a
Forging forming to positively buckle and form the desired tooth profile,
And, if necessary, a tooth forming shape process including three steps of a preliminary tooth forming shape and a tooth shape finishing process (for example, ironing) provided before and after forging, and a piercing process of processing a mounting hole and the like. In addition, if necessary, an appropriate heat treatment may be performed after the piercing.

FIG. 12 shows a drawing, a preliminary tooth formation,
This shows the side wall portion 2a which has undergone each step of forging and ironing as tooth shape finishing, so that the appearance, the side surface, and the change due to the processing of the plane can be understood for each step. The drawing process, substantially vertically deep drawn flat cylindrical side wall portion 2a on the periphery of the plate <br/> gold material body as a tooth profile forming position is formed. In the subsequent step of forming the preliminary teeth, the side wall portion 2a is formed into a gentle waveform. Next, in the forging process, the side wall 2a is forged and buckled to form a desired tooth profile. Thus, the height of the side wall portion 2a is crushed from _{h 1} to _{h 2.} In the final ironing step, although there is no change in the basic tooth profile, the removal of sink marks and the improvement in accuracy have been achieved by ironing the tooth profile surface. In addition,
G, H, and I in the figure are only reference numbers indicating the same position of the side wall 2a (ring gear 1), and do not mean that the details of the dimensions and the shape are the same. As the process proceeds, the width dimension corresponding to each code is G
Decrease, H increases, and I is approximately constant.

Now, the above-described tooth forming process is centered on the forging process shown in FIG. This forging method employs a method of positively buckling the side wall portion 2a and increasing the thickness of the desired tooth profile by moving the material of the side wall portion. FIG.
In the figure, 2a is a side wall portion subjected to forging, 5 is a die for forming teeth, 6 is a forging punch for applying a forging load in the direction of a hollow arrow, 7 is a restraining punch for restraining the inner diameter side of the side wall 2a, 2 is The drive plate is shown, (A) is each (B)
FIG. 3 is a cross-sectional view taken along line aa, line bb, and line cc of FIG.

In general, the condition for buckling of the side wall 2a is that the relationship between the thickness t and the height h _{0 of the} side wall shown in FIG. 2 is h ₀ / t.
It is said that ≧ 2. In the method of the present invention, the side wall 2a satisfying such conditions is provided in advance in the drawing process, and the buckling phenomenon that occurs when the side wall 2a is forged is positively used to form the tooth profile. It is. FIG.
The side wall portion 2a is formed with a preliminary tooth formation shape described later, but the side wall portion 2a shown in FIG. 2 may be directly forged and formed after the drawing step.

1A and 1B show the states before forging, the initial stage of forging (buckling), and the end of forging (formation), respectively, from the left in FIGS. 1A and 1B. In this embodiment, in order to form a tooth profile on the outer peripheral surface of the side wall portion 2a, a restraining punch 7 is disposed on the inner diameter side of the side wall portion 2a to restrict the movement of the side wall portion 2a toward the inner diameter side.

The purpose and operation of the restraining punch 7 will be described below with reference to FIGS. FIG. 3 shows an example of flat plate compression in which both the inner and outer diameters of the side wall portion 2a are not restricted. The side wall portion 2a compressed from the direction of the outline arrow has a characteristic of bulging outward and buckling. FIG. 4 shows a case where the outer diameter side of the side wall 2a is restrained by the die 5 and forging is performed. The side wall 2a is bent inward and buckled. In this case, the tooth profile formed on the outer peripheral surface side of the side wall portion 2a includes:
As shown in FIG. 4 (B), the material escapes inward to generate a large material defect 8. Therefore, in the method of the present invention,
The inner peripheral surface side (back side) of the tooth forming surface is constrained by the constraining punch 7 and forging molding is performed. As a result, the side wall portion 2a that has received the forging load from the forging punch 6 bulges outward (toward the die 5) and buckles, as shown in the initial state of forging pressure in FIG. I do. The formation of the gap 9 secures an escape area for the forged side wall material, and can avoid closed forging. Then, when a forging pressure load is further applied, as shown in the forging pressure final state in FIG.
The side wall material flows outward as roughly indicated by an arrow, and conforms to the shape of the die 5 to form a desired external tooth shape.
Since the closed forging can be avoided, a required tooth profile can be obtained without increasing the forging load.

By the way, in the tooth profile obtained by the above forging process, as shown in FIG. 5, sink marks 10 may be generated on the small diameter corner portion (concave portion) appearance according to the constraint condition of the material in the forging process. is there. FIG. 6 is a diagram (cross-section d-d in FIG. 5) for explaining the occurrence of sink marks, and shows a case where the left half has no spline portion constraint and a case where the right half has the spline portion constraint. The solid line in the figure shows the tooth profile after forging, and the dashed line shows the shape before forging.

In the case where there is no spline portion constraint shown in the left half of FIG. 6, the linear portion of the large and small diameter spline portion is barrel-shaped deformed (increased wall thickness) due to forging pressure, and the bent portions 11 and 12 are bent. Occurs. On the other hand, when the spline portion is constrained, the forged material flows into the gap 9 inside the tooth profile to increase the wall thickness. Therefore, in the spline concave shape 13, the inward flow of the small diameter and the spline portion merges to increase. , Sink marks 10.

Therefore, in order to restrain the inward flow of the material near the concave portion 13 which causes sink marks 10 during forging, the diameter D _p of the large diameter portion of the restraining punch 7 (see FIGS. 7 and 8) is expressed by the following equation (1).
Set as follows.

[0028]

[Number 1] _{D p} ≧ _{d d} Note, _{d d} in Equation 1 denotes a small-diameter portion diameter of the die 5, if the small-diameter portion diameter of restraining the punch 7 and _{d p, (d d}
-D _p) / 2 corresponds to _{t 1} in FIG. 8. Also, (D _p −
d _p ) / 2 is the height of the punch shown in FIG.
Height of 4) corresponds to _{h p,} a relationship of _{h p} ≧ _{t 1} between the _{t 1} and _{h p} (Transforming this _{D p} ≧ d
_d ).

Furthermore, if the inner major diameter of the pre-tooth shaped sidewall portion 2a and _{D y, D p} ≦ _D Equation 2 below from the relationship of _y is also established.

[0030]

[Number 2] the meets D _y ≧ d _d above conditions, the material of the forging sidewall portion 2a is suppressed inward flow causes shrinkage, the material flow (Figure to the tooth profile section 7 (arrow 15) and the material flow into the gap 9 (arrow 16 in FIG. 7) become dominant. For this reason, by adding a preliminary tooth forming step that satisfies the above conditions before the forging forming step, it is possible to increase the thickness of the tooth form while suppressing sink marks.

Although the method for preventing the occurrence of sink marks by adding the preliminary tooth forming step has been described above, a method for removing sink marks generated by forging in a subsequent step is also possible. The tooth shape finishing process for removing the sink marks includes, for example, ironing. As shown in FIG. 9, the ironing material 19 is ironed from the surface of the tooth profile between the punch 17 and the die 18. If this ironing amount is set to the sinking amount or more, the preliminary tooth forming shape before forging forming can be made into a shallow preliminary tooth forming shape, or the preliminary tooth forming shape can be omitted, and it is possible to directly form the preliminary tooth forming shape from the cylindrical material after the drawing process. It becomes possible to carry out tooth formation by forging pressure. In addition, this ironing is also a method implemented for the purpose of improving the accuracy of the tooth profile, and in some cases, it is also possible to simultaneously achieve sink removal and accuracy improvement.

Instead of the above-mentioned ironing, plastic working such as rolling or cutting with a hobbing machine or the like may be employed. Of the tooth profile and elimination of sink marks on the tooth surface can be achieved at the same time.

As described above, according to the method of the present invention, the thin sheet metal material can be formed by only the forging step, or by adding one or both of the preliminary tooth forming form and the tooth finishing processing to the forging form. It is possible to form a tooth-shaped part from, and all processing is possible within the load range of a general sheet metal transfer press, and no special machine is required. In addition, whether to add the steps of preliminary tooth formation and tooth finish finishing depends on the shape of the tooth profile as the product,
It can be selected as appropriate under conditions such as required accuracy specifications, and therefore can be applied in a wide range as a method of molding sheet metal tooth profile parts.

In the above embodiment, the tooth profile is formed on the outer periphery of the side wall portion. However, the tooth profile can be formed on the inner peripheral surface of the side wall portion by exchanging the positions of the die 5 and the restraining punch 7. is there.

[0035]

According to the first method for molding a sheet metal tooth profile according to the present invention described above, the side wall portion is actively buckled while the inner peripheral surface side of the tooth profile surface is restrained, and the buckling is caused by the buckling. Since a clearance for the material is ensured by the generated gap to avoid forging forging, a highly accurate tooth profile can be easily formed without increasing the forging pressure load.
In particular, since a high forging pressure load is not required, a series of press work from blanking to tooth piercing through piercing can be carried out with a transfer press for sheet metal, facilitating the production line configuration and improving productivity. It has a great effect. In addition, since it does not require a dedicated machine for tooth formation,
It is also effective in reducing product costs in combination with high productivity.

Next, according to the second sheet metal tooth profile forming method of the present invention, the amount of material movement (deformation) during forging is suppressed by adding a preliminary tooth forming step before forging. be able to. For this reason, sink marks can be prevented from appearing in the small-diameter corner portion appearance of the tooth profile at the time of forging, and a highly accurate and highly reliable product can be provided even for a deeply toothed tooth profile in which the dimensional difference between the large-diameter portion and the small-diameter portion is large. It can be manufactured by forging. In this case, processing by a series of transfer presses is also possible, which is effective for improving productivity and reducing costs.

Finally, according to the third method for forming a sheet metal tooth profile part according to the present invention, by adding a tooth profile finishing process such as ironing after forging, it is possible to improve tooth profile accuracy and remove sink marks. Can be performed at the same time, and forging forming can be performed without a preliminary tooth forming shape even if the tooth shape causes sink marks. In this case as well, a series of processing by transfer press is possible, which is also effective in improving productivity and reducing costs.

Further, a desired tooth profile may be formed through three steps of preliminary tooth forming, forging forming, and tooth profile finishing (ironing, rolling, or hobbing). Can be easily performed with high precision. Therefore, it is possible to appropriately select an optimal combination in consideration of productivity and cost according to conditions such as the tooth profile of the product and the accuracy required in specifications. Further, depending on the specifications of the product, since the material is work-hardened through the forming step of forging and ironing, it can be expected that the heat treatment conventionally performed after the piercing step becomes unnecessary.

The molding method of the present invention is applicable not only to the thickening of a tooth profile but also to the thickening of a cylindrical material.
For example, it is also effective in producing a material for tooth forming other than the press method.

[Brief description of the drawings]

FIG. 1 is a state diagram illustrating a forging process in a method of forming a sheet metal tooth profile part according to the present invention.

FIG. 2 is a cross-sectional view showing a shape of a side wall portion formed in a drawing step.

FIG. 3 is a view showing a state in which a side wall portion is flattened and buckled in a state where it is not restricted both inside and outside.

FIG. 4A is a view showing a state in which the outside of the side wall is restrained and buckled, and FIG. 4B is an external perspective view showing an example of a tooth profile formed by the method of FIG. .

FIG. 5 is a perspective view showing sink marks generated in the appearance of a small-diameter corner portion of a tooth profile.

FIG. 6 is a diagram for explaining the occurrence of sink marks in FIG. 5;

FIG. 7 is a diagram for explaining conditions for preventing sink marks.

FIG. 8 is a supplementary diagram of FIG. 7 for describing conditions for preventing sink marks.

FIG. 9 is a diagram showing a state of ironing.

FIG. 10 is a cross-sectional view of a main part showing a ring gear in an automatic transmission device for a vehicle manufactured by the molding method of the present invention.

FIG. 11 is a view showing main steps necessary for press-molding the ring gear of FIG. 10;

12 is a view showing a change in the shape of the side wall portion after each of the steps of drawing, preliminary tooth formation, forging forming, and ironing in FIG. 10;

FIG. 13 is a cross-sectional view of a main part showing a structural example of a ring gear in a conventional automatic transmission for a vehicle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ring gear 2 Drive plate 2a Side wall part 3 Torque converter 4 Flat plate (blank) 5 Die (for forging pressure) 6 Forging pressure punch 7 Restraining punch 8 Material lacking part 9 Air gap 10 Sink 11,12 Concave shape 13 Spline concave shape 14 Convex portion 17 Punch (For ironing) 18 Die (for ironing) 19 Ironing material

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Claims (3)

(57) [Claims] In a method of forming a tooth-shaped part made of sheet metal by forging a sheet metal material to form a tooth-shaped part, a peripheral portion of the sheet metal material body is drawn to a tooth forming position by drawing a sheet metal material body.
A drawing step of providing a flat-plate cylindrical side wall portion at the side, and the side wall portion is actively buckled in a state where the inner peripheral surface side of the tooth forming surface is restrained at the time of forging, and the upper end of the side wall portion is forged.
And a buckling thickening step of thickening and forming a desired tooth shape on the side wall portion . 2. A plate for forming toothed parts by forging a sheet metal material.
In the molding method of gold tooth profile parts, the sheet metal material body is drawn
A draw that has been machined to provide a side wall in advance at the tooth forming position
Forming step, and forming the side wall portion with preliminary teeth to form a forging pressure.
Preliminary tooth forming process to control material movement and tooth profile during forging
While the back side of the molding surface is restrained, the side wall portion is actively seated.
Buckling to form a desired tooth profile on the side wall
A method for forming a sheet metal tooth-shaped part, characterized by comprising a thickening step . 3. A tooth profile finishing step for forming a tooth profile with a desired dimensional accuracy and removing sink marks generated on the tooth surface after the buckling thickening step is performed. Or the molding method according to 2.