JP2003329072A - Method for manufacturing initially coned disc spring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture initially coned disc springs with better yield and reduced man-hours. <P>SOLUTION: A long strip-shaped material is sent in its longitudinal direction and bent in its widthwise direction to be annularly shaped. It is fitted in a cutting die having a predetermined diameter. An overlapping part of its head and tail is cut to form a strip-shaped and C-shaped member. Both ends of the member are bonded to each other to form an annular strip-shaped member. Then, the annular strip-shaped member is formed into the initially coned disc spring by forming the coned disc spring. The diameter Db of the cutting die is made to be a cutting allowance (t) in cutting plus the diameter of the initially coned disc spring. In this method for forming the initially coned disc spring by forming the strip-shaped material into the annular shape, no punching scrap is generated differently from the case where an annular material is punched out from a strip-like material to have the better yield, nor is a process of flattening a wire rod needed, so that the man-hours are reduced and the high- precision coned disc spring is formed. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc spring manufacturing method.

[0002]

2. Description of the Related Art One of the forms of springs is a disc spring having an annular shape and a V-shaped cross section. An example of the use of the disc spring is an automatic transmission for automobiles. In some of the automatic transmissions, a disc spring is used for cushioning when the clutch is engaged.

In a conventional disc spring manufacturing method, a flat plate material having a thickness when formed as a disc spring is used, and an annular material having a predetermined width in the radial direction from the flat plate material is pressed, for example. There is one in which the annular material is punched out by processing, taken out by heat and pressure, molded into a disc spring shape and quenched, and further tempered to form a complete disc spring. In addition, the peripheral edge of the disc spring is subjected to cutting or grinding such as deburring to obtain a finished product.

[0004]

However, in the above manufacturing method, since the annular material is taken out from the flat plate material, the circular center portion and the portion between adjacent ones are left as waste materials. Further, depending on the type of disc spring (difference in inner / outer diameter ratio as a finished product), the yield was only 12 to 30%.

In order to eliminate the above-mentioned poor yield, as disclosed in Japanese Unexamined Patent Publication (Kokai) No. 6-106277 by the same applicant, the wire rod is formed into an annular shape, and both ends thereof are butted and welded, and flattened by flattening. Ring-shaped disc spring material,
Then, there is one in which a disc spring is formed by heat and pressure molding.

[0006] According to the above manufacturing method, there is nothing to be left out when the material is taken out from the flat plate material, and no waste material is generated, so that the yield can be improved. However, since the step of forming the wire rod into an annular shape and crushing it into a flat shape is performed, there is a problem that the number of steps is large.

[0007]

In order to solve the above problems and to manufacture a disc spring with a good yield and a small number of steps, in the present invention, a long flat plate-shaped material is used. By sending in the longitudinal direction and bending in the width direction to form a leading part and a trailing part of the flat plate-shaped material in an annular shape by superimposing the annular part and a part having a predetermined diameter. A process of forming a flat plate C-shaped member by radially cutting the overlapping portion of the leading portion and the trailing portion by fitting in a cutting die, and facing each other in the flat plate C-shaped member. Which has a step of joining both ends to form a flat ring-shaped annular member, and a step of forming the flat plate-shaped annular member into a disc spring shape to form a disc spring, wherein the diameter of the cutting die is The diameter of the coned disc spring is determined by taking the cutting margin at the time of cutting into consideration.

According to this, since the long flat plate-shaped material is formed into an annular shape to form the disc spring, there is no portion to be removed when the ring-shaped material is taken out from the flat plate material, and the yield is good. At the same time, the process of flattening the wire rod is not required, and the number of steps can be simplified. At that time, the plate spring is easily formed by fitting a cutting die having a diameter in which a cutting allowance is added to the diameter of the disc spring to form a flat plate C-shaped member and joining both ends thereof to form the disc spring. Can be formed accurately.

Further, it is preferable that the flat plate-shaped material is thicker on the outer peripheral portion on the outer peripheral side than on the inner peripheral portion on the inner peripheral side when formed on the flat plate annular member. . According to this, when a flat plate-shaped material is bent to be formed into a flat plate-shaped annular member, the outer peripheral portion becomes relatively thin with respect to the inner peripheral portion, but the plate thickness is set in advance in consideration of the thinning. By doing so, it is possible to prevent the outer peripheral portion from becoming relatively thin when it is molded into a flat plate annular member, so that the thickness between the inner and outer peripheral portions that causes breakage in the disc spring can be reduced. The difference can be set arbitrarily.

Further, the plate thickness of the flat plate-shaped material is preferably set so that the outer peripheral side is thicker than the inner peripheral side in the state of the disc spring. According to this, since the outer peripheral side is thicker than the inner peripheral side in the state of a finished product formed as a disc spring, the inner and outer peripheral portions of the tensile stress distribution in the radial direction of the disc spring surface are The difference in can be reduced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail based on specific examples shown in the accompanying drawings.

FIG. 1 is a perspective view showing a disc spring material forming apparatus used in a method for manufacturing a disc spring to which the present invention is applied. A long flat plate-shaped material 1 made of, for example, steel, which is a material for the disc spring, is stored in a roll shape, for example, on the right side of the drawing (not shown). The flat plate-shaped material 1 is provided with a pair of left and right feed rollers 2 and 3 which are arranged apart from each other in the longitudinal direction.
It is designed to be transported in the longitudinal direction.

As shown in FIG. 2, the feed rollers 2 and 3 have roller portions 2a and 3a that abut on both side surfaces of the flat plate-shaped material 1 in the width direction and the roller portions 2a and 3a in the axial direction. Upper and lower flanges 2b and 3 provided so as to be sandwiched
and b. The edge portion of the plate-shaped material 1 is received between the upper and lower flange portions 2b and 3b.

In this way, the plate-shaped material 1 is regulated in the vertical and horizontal directions in its cross-sectional shape by the feed rollers 2.3. The pair of feed rollers 2 and 3 facing each other
By rotating the rollers in directions opposite to each other, the plate-shaped material 1 is fed out as indicated by an arrow A in FIG. 1 by frictional engagement of the roller portions 2a and 3a. In addition, a pressing load in a direction in which the plate-shaped material 1 is sandwiched by the pair of feed rollers 2 and 3 forming a pair is generated by, for example, hydraulic pressure,
A pressing force in the feeding direction of the plate-shaped material 1 can be generated. An R forming die 4 is arranged on the delivery extension line.

The R forming die 4 is provided with upper and lower guide portions 4a and 4b facing each other at a distance slightly wider than the thickness of the plate-shaped material 1 so as to guide the front and back surfaces of the plate-shaped material 1, and together with FIG. As shown, an R molding surface 4c having a predetermined radius R is formed between the upper and lower guide portions 4a and 4b. A cutting machine 5 is arranged between the feed roller 3 and the R molding die 4. The cutting machine 5 includes a fixed blade 5a and a movable blade 5b which are arranged with the plate-shaped material 1 interposed therebetween.

In the Belleville spring material forming apparatus configured as described above, the plate-shaped material 1 is sent out toward the R forming die 4 by the feed rollers 2.3 as shown by an arrow A in FIG. The plate-shaped material 1 is the upper and lower guide portions 4 of the R forming die 4.
It projects between a and 4b, and is bent by the R molding surface 4c in the width direction with a radius of curvature R. The bending process may be cold working.

Since the plate material 1 is bent by the R forming die 4 while being fed by the feed rollers 2 and 3, it is bent in an annular shape having a radius R as shown in the imaginary line in FIG. 1 and in FIG. Therefore, the leading portion 1a of the plate-shaped material 1 that is first bent by the R forming die 4 returns to the R forming die 4 in a circle with a radius R. In order to avoid the collision between the returning leading portion 1a and the trailing portion 1b which is newly bent, the end portion of the lower guide portion 4b of the R molding die 4 is guided to the leading portion 1a downward. Taper to.

As a result, at the R mold 4, the returning leading portion 1a and the trailing portion 1b, which has just begun to bend, overlap. The plate-shaped material 1 is cut by the cutting machine 5 so as to leave an overlapping portion of the leading portion 1a and the trailing portion 1b.
Is cut to obtain an annular ring blank 6 as shown in FIG.

In the next step, the ring blank 6 is
As shown in FIG. 4, the disc-shaped cutting die 7 is set.
This cutting die 7, as shown in FIG.
The boss portion 7a and the outward flange portion 7b are formed in a convex sectional shape having the same axis. The ring blank 6 is fitted into the boss portion 7a and placed on the outward flange portion 7b. Further, the cutting die 7 is provided with a radial slit 7c, and a thin blade grinding wheel 8 adapted to be aligned with the slit 7c is provided.

The leading portion 1a and the trailing portion 1 are provided in the slit 7c.
Ring blank 6 so that the overlapping part with b is positioned
Is set in the cutting die 7. Then, the thin-edged grindstone 8 is rotated into the slit 7c, and the overlapping portion of the leading portion 1a and the trailing portion 1b is cut to form the flat plate C-shaped member 8.

In the flat plate C-shaped member 8, a gap is formed in the cutting portion by the cutting margin t of the thin blade grinding wheel 8,
Due to the elastic restoring force, the cut surfaces as the opposite ends of the leading portion 1a and the trailing portion 1b can come into contact with each other, so that there is no gap. As shown in FIG. 5 (a), the cut surfaces of the leading portion 1 a and the trailing portion 1 b are beam-welded by, for example, an electron beam welding machine 9 to form a continuous flat annular member 9 in an annular shape. To form. Alternatively, laser welding may be used.

According to such beam welding, the leading portion 1
Since a and the trailing portion 1b can be joined to each other in a contact state,
There is no dimensional change in the circumferential direction due to welding. In the state of the flat plate-shaped annular member 9, as shown in FIG. 5 (b), it remains flat. Further, it is possible to build up the welded portion in the width direction and the thickness direction by forcibly narrowing down the dimension in the circumferential direction during welding. As a result, the corners of the rectangle in the cross-sectional shape of the welded portion are in a build-up state, so by removing the welded build-up portion by grinding after welding, the cross-sectional shape of the welded portion is the same as that of the other rectangular cross-section. (There is no dent due to melting sagging at the corner). Therefore, the cross-sectional shape does not become discontinuous at the welded portion, stress concentration on the welded portion can be avoided, and fatigue resistance is not impaired.

Then, the flat plate-shaped annular member 9 is formed into an annular dish shape by, for example, high-frequency heating and press forming, and at the same time, heat-treated (after quenching, rapidly cooled in the mold). Die quench treatment) is performed to form the disc spring 10 having a predetermined spring characteristic (FIG. 6).

As the finish of the disc spring 10, cutting such as deburring of the inner and outer circumferences, barrel polishing for smoothing the surface, and shot peening for improving durability are performed. These may be appropriate according to the specifications. Also,
A load test is conducted at the final stage to complete the product.

In the disc spring 10 thus formed, in the flat plate-shaped annular member 9 before being formed into a disc shape,
Assuming that the cutting reference inner diameter D (see FIG. 5A) is the reference value of the finished product, the boss portion 7a of the cutting die 7 in the previous process.
The outer diameter Db of is set to a value that takes the cutting margin t into the inner diameter D. Specifically, Db = D + t / π. Further, when a welding allowance for beam welding is provided, it is possible to set Db in consideration of the welding allowance.

By setting the outer diameter Db of the boss portion 7a as described above, the inner diameter of the flat plate-shaped annular member 9 welded in an abutted state after cutting can always be the cutting reference inner diameter D. This allows the dimensions of the finished product to be maintained with high precision and ease. Therefore, it is possible to realize uniform characteristics and low cost of the disc spring.

Further, in the disc spring when an axial load is applied to the inner peripheral portion, the compressive stress σ1 generated on the convex surface and the tensile stress σ2 generated on the concave surface are shown in FIG. 7 (for example, compressed to a plane). If). As shown in the figure, there is a large difference in stress between the inner peripheral portion and the outer peripheral portion.
Further, the fracture resistance of the disc spring is a tensile stress resistance. Therefore, description of the stress change on the compression side is omitted here. The maximum value of the stress distribution difference of the tensile stress is the difference between the tensile stresses in the inner and outer peripheral portions. By reducing the difference, the maximum stress can be reduced and the fracture resistance can be improved.

Further, in the above manufacturing process, when the ring blank 6 is formed, the inner peripheral side thereof is compressed to be thickened. Therefore, when the flat plate-shaped material 1 has a rectangular cross-sectional shape with a uniform plate thickness, the outer peripheral portion thereof is relatively thinner than the inner peripheral portion when formed into the ring blank 6, and the disc spring 1
The outer peripheral part where the maximum tensile stress at 0 is generated is thin,
The inner peripheral portion, which does not need to have relatively high strength, becomes excessively thick, which increases the weight.

According to the present invention, as shown in FIG. 8A, the thickness t1 of the outer peripheral portion 6a of the ring blank 6 is made larger than the thickness t2 of the inner peripheral portion 6b. That is, as shown in the phantom line in FIG. 8A, in the cross-sectional shape of the flat plate-shaped material 1, the inner peripheral portion 6b of the ring blank 6 is formed.
The thickness t3 of the portion to be set is made thinner than the thickness t2 in consideration of the increased thickness. The flat plate-shaped material 1 is bent to form a ring blank 6 having an outer peripheral portion having a thickness of t1 and an inner peripheral portion having a thickness of t2.

As a result, the strength of the outer peripheral portion 10a of the disc spring 10 is relatively increased, and the tensile stress distribution on the concave side surface of the disc spring is greater than that of the rectangular cross section as shown by the chain line 8a in FIG. Can also be flattened. further,
Since the difference in stress distribution between the inner and outer peripheral portions is reduced, the fracture resistance is improved and the durability is also improved. In the illustrated example, the upper and lower surfaces of the figure are both formed into an isosceles triangular cross-sectional shape with tapered surfaces, but it is also possible to use only one of them as a right-angled triangular shape.

Further, as shown in FIG. 8B, it is preferable to form one surface 6c (for example, the convex surface) by a roll process or the like so as to be a curved surface. As a result, as shown by the alternate long and two short dashes line 8b in FIG. 7, it is possible to make the surface flatter than that of the alternate long and short dash line 8a. The durability and durability can be further enhanced. The curved shape is not limited to the one surface 6c only, and both surfaces may be curved.
Further, it is not limited to a curved surface having a constant curvature, but any curved surface may be used as long as the change in the plate thickness in the radial direction is non-linear. By changing the design of the curved surface, the stress distribution change can be further flattened.

In the cutting using the cutting die 7, the method of cutting using the thin blade grinding wheel 8 has been shown, but the cutting method is not limited to this, and another example is shown in FIG. In the drawing, the same parts as those in the above-mentioned illustrated example are designated by the same reference numerals, and detailed description thereof will be omitted.

In the structure shown in FIG. 9, a cutting machine 11 similar to the cutting machine 5 is provided in place of the thin blade grindstone gear 8. The cutting machine 11 includes a fixed blade 11a and a movable blade 11b.
And is disposed so as to be received in the recessed portion 7d provided in the cutting die 7. When the ring blank 6 is set on the cutting die 7, the overlapping portion of the leading portion 1a and the trailing portion 1b is aligned with the recessed portion 7d, and the movable blade 11b is lowered to cut the overlapping portion. In this case, it is not necessary to set the cutting margin t, and the cutting die 7 can be easily designed.

[0034]

As described above, according to the present invention, since the flat plate-shaped material is formed into an annular shape to form the disc spring, there is no portion to be left out when the ring-shaped material is taken out from the flat plate material. The yield is good, and the process of flattening the wire is not required, and the number of steps can be simplified.

When a flat plate-shaped material is bent to form a flat plate-shaped annular member, its outer peripheral portion becomes relatively thin with respect to the inner peripheral portion, but the plate thickness is set in advance in consideration of the thinning. By doing so, it is possible to prevent the outer peripheral portion from becoming relatively thin when it is molded into a flat plate annular member, so that the thickness between the inner and outer peripheral portions that causes breakage in the disc spring can be reduced. The difference can be reduced. This allows
Improves fracture resistance and has the same cross-sectional area (same weight)
In the case of, the maximum allowable load can be increased more than that of the disc spring having a uniform cross section.

Further, since the outer peripheral side is thicker than the inner peripheral side in the state of a finished product formed as a disc spring, the tension stress distribution in the radial direction of the disc spring surface is distributed between the inner and outer peripheral portions. Can be reduced, and the fracture resistance can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a disc spring material forming apparatus to which the present invention is applied.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a fragmentary plan view of the disc spring material forming apparatus of FIG.

4A is a plan view showing a cutting die, and FIG. 4B is a side sectional view thereof.

FIG. 5 (a) is a plan view showing a flat annular member,
(B) is the sectional side view.

6A is a plan view showing a disc spring, and FIG. 6B is a side sectional view thereof.

FIG. 7 is a diagram showing a stress distribution of a disc spring.

FIG. 8A is a diagram showing another example of the sectional shape of the disc spring, and FIG. 8B is a diagram showing yet another example.

9A is a plan view showing another example of the cutting die, FIG.
(B) is a side view seen from the arrow IX line in (a).

[Explanation of symbols]

1 Flat material 2.3 Feed roller 4 R Mold 5 cutting machine 6 ring blank 7 cutting type 8 thin blade grinding wheel 9 Electron beam welder 10 Disc spring

Claims (3)

[Claims] 1. A process of feeding a long flat plate-shaped material in the longitudinal direction and bending it in the width direction to form a leading part and a trailing part of the plate-shaped material to form an annular shape, A process of fitting an annular member into a cutting die having a predetermined diameter, and cutting the overlapping portion of the leading portion and the trailing portion in the radial direction to form a flat plate C-shaped member; A step of joining opposite ends of the flat plate C-shaped member to form a flat plate annular member, and a step of forming the flat plate annular member into a disc spring shape to form a disc spring. And a diameter of the cutting die is a diameter in which a cutting margin at the time of cutting is added to a diameter of the disc spring. 2. A plate thickness of the flat plate-shaped material is thicker on an outer peripheral part on an outer peripheral side than an inner peripheral part on an inner peripheral side when formed on the flat plate-shaped annular member. The method for manufacturing a disc spring according to claim 1, which is characterized in that. 3. The plate thickness of the flat plate-shaped material is set so that the outer peripheral side is thicker than the inner peripheral side in the state of the disc spring. Belleville spring manufacturing method.