JP2001314921A - Local thickness increase method by press working - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To press-mold a deep dish or cup-shaped molded product by upright molding of a flange portion, relatively increase the thickness of a corner portion corresponding to the root portion of the flange portion. Flesh. SOLUTION: In upsetting in which a flange portion 2 formed in a preceding step is swaged in a height direction thereof, a radius of curvature of an outer curvature surface 5B of a corner portion 5 is set to be smaller than a normal radius of curvature required for a molded product. The thickness T of the corner portion 5 is made thicker than the thickness t of the other portions (FIG. 8).
(A) to (C)). In the case of the secondary molding following the upset molding (FIG. 8D), the outer curvature surface 5b of the corner portion 5 is formed.
Is applied so that the radius of curvature becomes a normal radius of curvature, but the thickened plate thickness dimension T is maintained as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for increasing a local thickness by press working, and more particularly to a method for increasing the thickness of a corner portion which is at least a root portion of a flange portion which is formed upright at an end portion of a plate-like work made of sheet metal. The present invention relates to a method for making the thickness larger than the thickness of a base material plate.

[0002]

2. Description of the Related Art For example, in bending a deep dish or cup-shaped work from a base material having a uniform thickness, a method of locally thickening a flange portion to be formed upright is disclosed in There is one described in JP-A-6-218442.

In this conventional technique, an end face to be a front end face of the flange portion is previously formed into a tapered shape at a flat base material stage, and then drawn into a substantially cup shape with a die and a punch. The flange is set up in a direction to reduce the height dimension of the flange portion while restraining the work with a punch having a radius of curvature smaller than the radius of curvature of the inner curved surface of the corner portion at the base of the flange portion. The part is made thicker.

[0004]

In such a processing method, although the thickness of the flange portion can be increased, the purpose is to increase the thickness of the flange portion itself. The material does not sufficiently reach the bottom wall surface of the corner portion, and there is a limit in increasing the thickness of the corner portion itself. Therefore, when the work is, for example, a rotating part, there is a natural limit to improve the rigidity by increasing the thickness of the corner portion itself.

In addition, since the end face to be the front end face of the flange portion needs to be formed into a tapered shape in advance in the flat base material stage as pre-processing, the number of processing steps and the cost increase due to the increase in the number of processing steps are inevitable. You.

The present invention has been made in view of the above problems, and does not require taper processing of the material end face as pre-processing, and can locally increase the thickness of the root corner itself of the flange. The purpose of the present invention is to provide a processing method.

[0007]

According to a first aspect of the present invention, the thickness of a corner portion which is a root portion of at least a flange portion of a flange portion formed upright on an end portion of a plate-like work is set as a base material. It is a method of increasing the wall thickness than the plate thickness, and in upsetting the flange portion formed upright in advance in the direction of reducing the flange height using a die and a punch,
By setting the radius of curvature of the molding surface of the die or punch controlling the molding of the outer curvature surface of the corner portion smaller than a predetermined dimension in advance, the curvature radius of the outer curvature surface of the corner portion is required for the product shape. The flange portion is upset formed so as to have a smaller radius of curvature. Then, following the upset forming, the secondary forming is performed such that the radius of curvature of the outer curved surface of the corner portion becomes the radius of curvature required for the product shape while restricting the flange portion to the upset height. It is characterized by doing.

In the upsetting, if the radius of curvature of the inner surface of curvature is reduced together with the radius of curvature of the outer surface of curvature of the corner portion, the effect of increasing the wall thickness or the effect of increasing the wall thickness is increased, but the inner surface of curvature is buckled. When the radius of curvature of the inner surface of curvature is increased together with the radius of curvature of the outer surface of curvature at the corner portion, buckling as described above is eliminated, but the effect of thickening or increasing the thickness is small. Therefore, when setting the radius of curvature of the outer curvature surface, the radius of curvature is set to an appropriate size.

Therefore, according to the first aspect of the present invention, by setting the radius of curvature of the outer curvature surface to be smaller than the prescribed dimension in the upset forming, material is positively applied to the outer curvature surface side. By securing it, the effect of increasing the thickness or increasing the thickness of the corner portion itself is obtained.

At this stage, since the outer and inner curvature surfaces of the corner portion do not have the prescribed dimensions, the flange portion is constrained to the previous upsetting height size following the upset molding. The secondary molding is performed so that at least the radius of curvature of the outer curvature surface and the radius of curvature of the inner curvature surface at the corners become the radius of curvature required for the product shape. By doing so, the material moves by plastic flow while maintaining the thickening or thickening effect of the corner portion itself, and the radius of curvature of the outer curved surface and the inner curved surface of the corner portion is finished to a specified size. Can be

In the molded article formed by such a procedure, the thickness at the corner portion, which is the root of the upright-formed flange section, is locally thickened. When it is cup-shaped or deep-dish-shaped and used as a rotating part, the rigidity of the thickened corner is high, which is extremely advantageous in terms of mechanical strength.

According to a second aspect of the present invention, the radius of curvature of the die or punch forming surface which controls the formation of the outer curved surface of the corner portion is set to be larger than the prescribed dimension, while assuming the invention of the first aspect. In addition to being set small, a concave step is formed in advance on the molding surface, and the radius of curvature of the outer curved surface of the corner becomes smaller than the radius of curvature required for the product shape, and the concave step is formed. The flange portion is upset formed so that the shape is transferred to the outer curvature surface. At the time of secondary molding subsequent to the upset molding, the erasing and restoring of the concave step shape transferred to the outer curvature surface is performed so that the outer curvature surface becomes a substantially flat C chamfered shape. It is characterized by being molded.

Therefore, according to the second aspect of the present invention, the outer curved surface of the corner portion is formed to be smaller than the prescribed size, and at the same time, the concave step shape is transferred and formed, so that the outer curved surface is more positively moved toward the outer curved surface. Material can be secured in a proper manner. Then, in the secondary molding following the upsetting, in order to erase and restore the concave step shape transferred to the outer curvature surface, the outer curvature surface has a substantially flat C-chamfered shape so as to be restored. Then, similarly to the first aspect of the present invention, the material moves by plastic flow while maintaining the thickening effect or the thickening effect of the corner portion itself, and the outer curvature surface and the inner curvature surface of the corner portion. Is finished to the specified dimension.

Particularly, as in the third aspect of the present invention, the concave step portion formed on the molding surface of the die or punch is formed at a position near the opposite flange portion in the portion that controls the molding of the outer curvature surface. In this case, the plastic flow is controlled such that the material flows positively to the flange portion side by the resistance of the concave step portion during upsetting. As a result, the effect of increasing the thickness or increasing the thickness of the outside curvature surface of the corner portion becomes even more remarkable.

[0015]

According to the first aspect of the present invention, the flange portion is upset so that the radius of curvature of the outer curved surface of the corner portion, which is the root portion of the upright formed flange portion, is smaller than a specified dimension. Subsequently, since the thickness of the corner portion is locally increased by secondary forming so that the radius of curvature of the outer curvature surface becomes a specified dimension, the corner portion is locally formed. In addition to being able to easily mold a thick molded product with a small number of steps, the mechanical strength of the corners of the molded product is greatly improved.

In particular, as in the second aspect of the present invention, when the transfer molding of the concave step is used together, the effect of increasing the wall thickness or the effect of increasing the thickness at the corner portion becomes remarkable, and the third aspect of the present invention. As in the present invention, when the transfer molding of the concave step portion is limited to a position near the flange portion in the corner portion, the effect becomes more remarkable.

[0017]

FIG. 3 is a diagram showing a more specific embodiment of the processing method according to the present invention.
2 shows an example of molding a molded article 1 as shown in FIG.

The molded article 1 shown in FIGS. 1 and 2 is formed into a substantially deep dish shape by drawing and forming the flange portion 2 upright from a disk-shaped material. On the 3 side, an annular convex portion 4 is formed to bulge. If the base material plate thickness t is, for example, 5.0 mm, the molded product 1
In view of the above function, the radius of curvature of the inner curved surface 5a of the corner portion 5 formed by the flange portion 2 and the bottom wall portion 3 is R1 or more, for example, R6, and the thickness T of the corner portion 5 is 5.5 mm, for example.
That is required. It should be noted that the thickness T at the corner portion 5 is 1.1 of the base material thickness t in a simple calculation.
However, in the case of ordinary drawing, the thickness at the corner 5 becomes smaller than the base material thickness t due to its elongation deformation, so that the required thickness T of the corner 5 is required.
Is substantially 1.2 times or more as compared with the conventional size.

The outline of the molding procedure of the molded article 1 is as follows. First, as shown in FIG. 3, a single-acting press die 6 is used to perform primary drawing (extension forming) using a disk-shaped sheet metal material (plate-shaped work) W to form a simple curved shape bulging upward. Then, as shown in FIG. 4, secondary drawing is performed by the single-acting press mold 7 to form the annular convex portion 4 on the bottom wall 3 side. Further, as shown in FIG. 5, similarly, a single-acting press die 8 is used to perform a flange bending process (flange down process), and the flange portion 2 is formed upright from the base material to form a substantially deep dish shape. At this time, the height of the flange portion 2 is not particularly restricted.

After the flange 2 has been formed, the sheet metal material W is transferred to another single-acting press die 9 as shown in FIG. The flange portion 2 is set up in the height direction by crushing and deforming from the bottom wall portion 3 side with the upper mold shape, and the thickness T of the corner portion 5 which is the root portion of the flange portion 2 is adjusted while adjusting the overall shape. Increase the thickness.

The single-acting press die 9 is provided with a punch 10
And a floating punch 12 fixed to a punch holder 11 movable relative to the punch 10, while an upper die that moves up and down with respect to the lower die is a die fixed to a die holder 13. 14 and a floating die 15 that can move relative to the die 14. Then, the die 14 forming the upper die is formed.
Since the boundary between the floating die 15 and the floating die 15 is set near the root of the flange portion 2, the floating die 15 mainly controls the molding of the bottom wall 3 of the molded product W. Reference numeral 14 mainly controls the formation of the corner portion 5 at the root of the flange portion 2 while restraining the side surface of the flange portion 2.

Here, as shown in FIG. 7, a punch 1 for controlling the formation of the inner curvature surface 5a of the corner portion 5 is provided.
0 is the radius of curvature R of the inner curved surface 5a required for the shape of the molded product 1 shown in FIG.
1, while the radius of curvature of the radius forming surface 14a on the die 14 side, which is responsible for forming the outer curvature surface 5b of the corner portion 5, depends on the shape of the molded product 1. The radius of curvature of the required outer curvature surface 5b is set to be smaller in advance.

The behavior during the upset molding will be described with reference to FIG. 8. As shown in FIG. 8A, when the distal end surface of the flange portion 2 is regulated by the floating punch 12 from an early stage, the floating die 15 Even if the pressure restraining force is applied, when the die 14 has not reached the bottom dead center, the portion of the bottom wall 3 near the corner 5 is in a state of being lifted from the punch 10. From this state, when the die 14 further descends together with the floating die 15 or alone, as shown in FIG.
As the material is crushed and deformed, the plastic flow causes the material to flow toward the bottom wall 3 and simultaneously flow toward the flange 2.

Then, as shown in FIG.
Reaches the bottom dead center, the space filled with the punch 10, the floating punch 12, the die 14, and the floating die 15 is filled with the material, and the outer curvature surface 5B of the corner portion 5 particularly has the die 14 side. Is transferred, and the radius of curvature of the outer curved surface 5B is smaller than the radius of curvature of the outer curved surface 5b finally required for the shape of the molded product 1 as described above. Is done. At this time, as shown in FIG. 7, depending on the behavior when the bottom wall portion 3 is crushed and deformed, the inner curvature surface 5a of the corner portion 5 is formed.
There is a case where a space G is formed between the punch 10 and the round forming surface 10a on the punch 10 side without closely contacting the two, but there is no problem because the secondary forming is performed in a later step. The thickness T of the corner portion 5 formed as described above is larger than the base material plate thickness t.

Here, the effect of increasing the thickness or increasing the thickness of the corner portion 5 requires the radius of curvature of the radius forming surface 14a on the die 14 side to be the shape of the molded product 1 as described above. This is obtained by forming the outer curvature surface 5b smaller than the radius of curvature of the outer curvature surface 5b in advance.
As shown in FIG.
When the radius of curvature of the inner curvature surface 5a formed by the 0-side radius forming surface 10a is reduced, the above-described effect of increasing the wall thickness or increasing the thickness becomes remarkable, and buckling Q easily occurs on the inner curvature surface 5a. Conversely, when the radius of curvature of the inner curvature surface 5a is increased together with the radius of curvature of the outer curvature surface 5B as shown in FIG. 7B, buckling on the inner curvature surface 5a can be prevented. The effect of increasing the thickness cannot be expected. Therefore, in the present embodiment, the radius of curvature of the radius forming surface 10a that controls the formation of the inner curvature surface 5a is finally changed to the extent that the buckling Q does not occur on the inner curvature surface 5a. It is set to the same size as the radius of curvature R1 required for the surface 5a.

Thereafter, the sheet metal material W having been subjected to the upsetting is pressed and constrained by another single-acting press-type punch 16 and die 17 equivalent to those in the previous step, as shown in FIG. Then, secondary molding is performed as finish molding, and the pressure is formed so that the outer curved surface 5B of the corner portion 5 becomes the outer curved surface 5b having a radius of curvature required for the molded article 1. At this time, the radius of curvature of the radius forming surface 16a on the punch 16 side is the same as that in the previous step, while the radius of curvature of the radius forming surface 17a on the die 17 side is the corner portion 5 of the molded product 1.
Among them are the same as the radius of curvature of the outer curvature surface 5b.

As a result, as shown in FIGS. 7 and 8C, the outer curvature surface 5b and the die 14 for upsetting are formed.
Although the part of the material corresponding to the difference from the radius forming surface 14a on the side plastically flows as if it fills the space G in the figure, the radius of curvature of the outer curvature surface 5B is required for the shape of the molded product 1. Even if the secondary molding is performed so as to have the outer curvature surface 5b having the radius of curvature to be performed, the effect of increasing the thickness or increasing the thickness of the corner portion 5 in the previous process is maintained, and FIG.
As shown in FIG. 2, the molded product 1 in which the thickness T of the corner portion 5 is locally thickened is obtained.

According to the present embodiment, the corner 5
As an effect of increasing the thickness or increasing the thickness of the steel sheet, an increase of 20% or more as compared with the conventional one was confirmed.

FIGS. 10A and 10B are views showing a second preferred embodiment of the processing method according to the present invention. In this embodiment, as apparent from comparison with FIG. At the same time when the radius of curvature of the radius forming surface 14a on the die 14 side which controls the forming of the outer curvature surface 5B at the time of the upsetting of the part 2 is formed smaller than the curvature radius of the outer curvature surface 5b required for the molded product 1. , The bottom wall 3 of the radius forming surface 14a
, That is, a concave step portion 19 is formed at a position close to the flange portion 2.

In this embodiment, as is apparent from a comparison between FIG. 10A and FIG.
When the bottom wall 3 is crushed and deformed, when the end of the concave step 19 bites into the material W, this becomes a resistance, and the movement of the material toward the bottom wall 3 due to plastic flow is partially caused. It will be restricted. As a result, the shape of the concave step portion 19 is transferred to the corner portion 5 as it is, and more material is retained on the outer curvature surface 5B side of the corner portion 5 so that the corner portion 5 has more material. The effect of increasing the thickness or increasing the thickness of the portion 5 becomes significant. However, as is clear from FIG. 10B, since the amount of material that relatively wraps around the inner curvature surface 5a is reduced, there is a space between the inner curvature surface 5a and the radius forming surface 10a on the punch 10 side. G becomes easier.

At the time of secondary molding following the upset molding, as shown in FIG. 11A, a single-acting press-type punch 20 and a die 21 which are substantially the same as those in the previous step are used to form the corner 5 side. While erasing and restoring the transfer shape of the concave step portion 19 formed in the above, a chamfered portion 5c is formed by performing a printing pressure molding to apply a flat C chamfer to the outer curvature surface. As a result, the material previously positively held on the outer curvature surface side with the transfer shape of the concave step portion 19 becomes the radius-formed surface 2 on the punch 20 side.
It flows to fill a space G formed between the inner surface 0a and the inner curvature surface 5a, and is finished in a predetermined shape. At this time, as apparent from a comparison between FIG. 11 (A) and FIG. 11 (B) corresponding to FIG. 10 (B), the effect of thickening or thickening at the time of the upset molding is apparent. Corner 5 formed
There is no change between the sheet thickness dimension T1 and the sheet thickness dimension T2 after the secondary molding, and the effect of increasing the wall thickness at the time of upsetting or increasing the thickness is inherited as it is after the secondary molding.

According to the present embodiment, the above-mentioned concave step portion 1 is formed.
9NI has an advantage that the effect of increasing the thickness or increasing the thickness T of the corner portion 5 becomes more remarkable as compared with the first embodiment.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing an example of a molded product in which a corner portion is locally thickened.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is an explanatory view of a first step for molding the molded article of FIG. 1;

FIG. 4 is an explanatory view of a second step for molding the molded article of FIG. 1;

FIG. 5 is an explanatory view of a third step for molding the molded article of FIG. 1;

FIG. 6 is an explanatory view of an upsetting process for forming the molded product of FIG. 1 as the first embodiment of the present invention.

FIG. 7 is an enlarged view of a main part of FIG. 6;

FIG. 8 is a process explanatory view showing details at the time of the upsetting.

FIG. 9 is an explanatory diagram showing a correlation between the radius of curvature of the inner and outer curvature surfaces of the corner portion and the wall thickness increasing effect.

FIG. 10 is a diagram showing a second embodiment of the present invention, and FIG.
(B), the principal part enlarged view at the time of upsetting corresponding to (C).

FIG. 11 is an enlarged view of a main part during secondary molding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Molded product 2 ... Flange part 3 ... Bottom wall part 5 ... Corner part 5b, 5B ... Outer curvature surface 5c ... Chamfering part 10 ... Punch 14 ... Die 14a ... Round forming surface 19 ... Concave step part t ... Base material plate thickness T: Sheet thickness at corner W: Sheet metal material

Claims (3)

[Claims] 1. A method of increasing the thickness of at least a corner portion, which is a root portion of a flange portion of a flange portion formed upright on an end portion of a plate-like work, than a thickness of a base material, In upsetting the flange portion that has been formed upright in advance in the direction of reducing the flange height using a die and a punch, the radius of curvature of the die or punch forming surface that governs the formation of the outer curved surface of the corner portion is determined. By previously setting smaller than the prescribed size, the flange portion is upset-formed so that the radius of curvature of the outer curved surface of the corner portion is smaller than the radius of curvature required for the product shape. Subsequent to the forming, the secondary forming is performed such that the radius of curvature of the outer curved surface of the corner portion becomes the radius of curvature required for the product shape while restraining the flange portion to the upsetting height. Local thickness increase process by press working, wherein. 2. The method according to claim 1, wherein a radius of curvature of a molding surface of a die or a punch for forming an outer curvature surface of the corner portion is set smaller than a predetermined dimension in advance, and a concave step is formed on the molding surface in advance. Upsetting the flange so that the radius of curvature of the outer curvature surface of the corner portion is smaller than the radius of curvature required for the product shape and the shape of the concave step is transferred to the outer curvature surface. At the time of secondary molding following upset molding, while performing erasing and restoring the concave stepped shape transferred and formed on the outer curvature surface, press forming is performed so that the outer curvature surface becomes a substantially flat C chamfered shape. 2. The method according to claim 1, wherein the local thickness is increased by press working. 3. The concave step portion formed on the molding surface of the die or punch is formed at a position closer to the opposite flange portion in a portion that controls the molding of the outer curvature surface. 3. The method for increasing the local thickness by press working described in 1.