JP2853536B2 - Sheet material drawing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for drawing a sheet material.

[0002]

2. Description of the Related Art In the press forming of a plate material, drawing is a frequent working method, and is applied to many parts from small parts to large parts such as a car outer plate, a sink, a bathtub, and the like.

FIG. 5 shows an example of a conventional ordinary drawing method. In FIG. 5, reference numeral 1 denotes a punch, 2 denotes a die, 3 denotes a wrinkle holding plate, and 4 denotes a workpiece. The punch 1 is pressed in a state in which the workpiece 4 is held by the die 2 as a die 2 with a predetermined force. Thus, drawing is performed. However, in drawing, wrinkling and breakage often cause problems as defects. To suppress the generation of wrinkles, it is necessary to add the pinching force as high as possible.However, if the pinching force is increased, the frictional force between the die and the wrinkle presser plate inevitably increases. It hinders the inflow of the material and eventually breaks.

On the other hand, when the frictional force between the workpiece and the die and the wrinkle holding plate is reduced by using a press working oil having a good lubricating property, it is effective for avoiding breakage, but wrinkles are prevented. It is easy to occur. Thus, in drawing, it is difficult to avoid wrinkles and breakage at the same time.
In particular, in drawing of complex parts, the workability of the workpiece is different depending on the part of the molded product, so breaks are likely to occur in parts that are difficult to be drawn, and wrinkles and surface distortions are likely to occur in parts that are easily drawn. Defects are more likely to occur, and the fact is that we are struggling with countermeasures.

Conventionally, the following methods have been considered to solve these problems. As a method often used for improving drawability, there is a method of molding using a high-viscosity press oil having excellent lubricity.

[0006] As a method other than the method of forming using a press working oil, see Document 1 [Plasticity and Working, Vol. 25, no.
(1984), p831], the opposed hydraulic pressure reduction method described in
A peripheral hydraulic drawing method described in [Plasticity and Working, Vol. 26, no. 288 (1985), p. 73] has been proposed. The opposing hydraulic drawing method is a processing method in which a workpiece is drawn using a rigid punch into a mold filled with liquid. The liquid, which is an incompressible body, flows out of the mold as the punch is pushed, so that the frictional force between the die and the workpiece can be reduced. The peripheral hydraulic drawing method is based on the above-described counter hydraulic drawing method, and is a method in which high-pressure liquid generated in a mold is applied as a compressive force to a plate surface at an outer edge of a workpiece through a bypass circuit. It is.

[0007]

However, the above-mentioned prior art has the following problems. The use of a high-viscosity oil makes it difficult to apply oil before molding and degreasing after molding, leading to a decrease in productivity. In addition, the use of a high-viscosity oil worsens the press working environment, increases the frequency of dust attached to a mold or a pressed part, and sometimes impairs the surface quality of a molded product. Even if such disadvantages are eliminated, there is naturally a limit to the improvement of workability by press working oil, and breakage cannot be avoided in severe drawing.

On the other hand, when the opposing hydraulic drawing method is applied, in addition to the load required for forming a workpiece into a punch,
An extra back pressure load is required to push out the liquid in the mold. This back pressure load is determined by the product of the hydraulic pressure generated in the mold and the projected area of the punch. Since this is much larger than the original molding load, it has a very large pressurizing capacity compared to normal molding. A press machine is required. Also, since a large amount of liquid needs to be supplied for each part processing,
Production efficiency is significantly reduced. Further, the pressure of the outflowing liquid is uniform at any part, and it is difficult to selectively reduce the frictional force only in the part where the workpiece is hardly drawn.

Further, it is said that the drawability of the peripheral hydraulic drawing method is further improved, but the drawback of the opposed hydraulic drawing method is directly followed and has not been improved. Further, in this peripheral hydraulic drawing method, it is necessary to take measures to prevent the liquid such as a seal from flowing out over the entire outer periphery of the mold, which makes the production of the mold difficult and causes another problem of durability.

[0010] The present invention overcomes the drawbacks in drawing and uses a general-purpose press having no special function or ability to avoid wrinkles and breaks simultaneously without impairing production efficiency, and An object of the present invention is to provide a drawing method of a sheet material having extremely excellent drawing workability and a device therefor, which can selectively reduce a frictional force only at a necessary portion.

[0011]

The above object is achieved by the following means. When machining draw forming a plate material, the liquid discharge port provided on part or the entire circumference of the die or the blank-holding plate or die both other mold opposite the mold provided with a liquid discharge port
The portion facing the liquid discharge port in the above is a flat surface,
A drawing method of a plate material, wherein drawing is performed while applying a liquid having pressure to a work material sandwiched between a die and a wrinkle holding plate from a discharge port .

[0012] In an apparatus for drawing and forming a plate material, a liquid discharge port is provided at one or a part of a die of a die and / or a wrinkle holding plate, and a metal provided with the liquid discharge port is provided.
Facing the liquid discharge port in the other mold facing the mold
An apparatus for drawing a plate material, characterized in that a part has a flat surface and means for adding a liquid having a pressure to a work material sandwiched between a die and a wrinkle retainer plate is provided. In the above apparatus, there is provided an apparatus for drawing a plate material, wherein a liquid supply groove connected to a liquid discharge port is provided.

[0013]

When the drawing is performed by the method of the present invention, since a liquid having a pressure continues to exist between each surface of the workpiece and the die or the workpiece and the wrinkle holding plate, the workpiece and the die or The frictional force between each surface of the workpiece and the wrinkle holding plate can be significantly reduced, and breakage can be avoided.

In order to suppress wrinkles, a pressurized liquid is applied to a workpiece from a die or a wrinkle holding plate or both, so that the material to be processed is a die or a wrinkle holding plate or a die and a wrinkle holding plate. Since the molding proceeds while being affixed to both of them at a uniform surface pressure, non-uniformity which is a starting point of wrinkle generation is eliminated, and a substantial wrinkle holding force is increased. Due to the synergistic effect of these two effects, the generation of wrinkles is dramatically reduced as compared with the case where the workpiece is simply clamped by the die and the wrinkle holding plate. Here, when the plane position of the liquid discharge port is not overlapped by the die and the wrinkle holding plate, the effect is large.

[0015]

FIG. 1 is a sectional view showing an example of a state immediately before drawing when drawing is performed using a double action press according to the method of the present invention, and FIG. 2 uses a single action press according to the method of the present invention. FIG. 3 is an example of a sectional view of a state immediately before drawing when performing drawing and drawing, FIG. 3 is an example of a plan view of a die or a wrinkle holding plate when performing cylindrical forming by the method of the present invention, and FIG. FIG. 4 is an example of a plan view of a die or a wrinkle holding plate when performing square tube molding.

In FIGS. 1 to 4, the same parts as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. Figure 1
In FIG. 4, 5 is a die cushion pin, 6 is a liquid supply hole formed in the die 2 or the wrinkle holding plate 3, 7 is a liquid supply device,
8 is a liquid supply pipe connecting the liquid supply device 7 and the liquid supply hole 6,
Reference numeral 9 denotes a liquid discharge port for adding the liquid supplied through the liquid supply hole 6 formed in the die 2 or the wrinkle holding plate 3 between the workpiece 4 and the die 2 and the wrinkle holding plate 3; This is a liquid supply groove provided when the liquid discharged from the liquid discharge port 9 through the liquid supply hole 6 formed in the holding plate 3 is distributed to a wide area.

When performing drawing by such an apparatus, for example, in the case of the drawing apparatus shown in FIG. 1, the workpiece 4 is placed on the die 2 and pressed and clamped by the wrinkle holding plate 3. Thereafter, when drawing is performed by lowering the punch 1, it is pressurized by the liquid supply device 7 and passes through the liquid supply pipe 8 and the liquid supply hole 6 and the liquid discharge port 9 formed in the die 2 or the wrinkle holding plate 3. The supplied liquid is set on a part or the whole circumference near the contour of the die hole of the die 2 or the wrinkle holding plate 3 or both, and the liquid supply groove 10 connected to the liquid discharge port 9 is provided.
Thus, drawing is performed while being added to the workpiece sandwiched between the die 2 and the wrinkle holding plate 3. Thereby, suppression of wrinkles and avoidance of breakage can be achieved at the same time, and it becomes possible to easily process a good drawn product without wrinkles or breakage.

At this time, the liquid supply device 7 used in the present invention comprises:
Any device having a function of controlling the hydraulic pressure and the additional timing may be used, and the details of the mechanism are not limited. In addition, the time for applying the high-pressure liquid is basically immediately after the workpiece 4 is clamped between the die 2 and the blanking plate 3.
May be added before being held between the die 2 and the wrinkle holding plate 3, or may be added at a time when the forming proceeds to some extent and wrinkles or breakage starts to occur. The location and range of the high-pressure liquid are determined by the position of the liquid discharge port 9 and the size and shape of the liquid supply groove 10 for distributing the high-pressure liquid added from the liquid discharge port 9 to a wide area. It is desirable to select according to the shape and processing form of the processed product.

In other words, the high-pressure liquid is added in the direction perpendicular to the hole contour line (drawing direction) of the die or the wrinkle retainer plate in the vicinity of the hole contour line of the die or the wrinkle retainer plate where wrinkles are most likely to occur. It is desirable to
This is also effective against breakage to facilitate the application of high pressure liquid to the die shoulder where the frictional force is highest.

On the other hand, the optimum position of the die hole contour line direction differs depending on the processing mode. For example, in the case of the axisymmetric cylindrical drawing shown in FIG. 3, it is necessary to set uniform processing conditions on the entire circumference, and high-pressure liquid is applied to the entire surface of the workpiece 4 sandwiched between the die 2 and the wrinkle holding plate 3. It is desirable to add.

For example, in the case of drawing a non-axisymmetric square cylinder shown in FIG. 4, the processing of the corners is the strictest, but on the other hand, the drawing of the right side is too large because the material inflow is excessive. Beko easily occurs on the wall. In such a case, it is desirable to apply the high-pressure liquid to only the corners of the workpiece 4 sandwiched between the die 2 and the wrinkle holding plate 3.

Further, the high-pressure liquid exerts a sufficient effect even when it is added to the die 2 or the wrinkle-holding plate 3 alone, but is applied from both the die 2 and the wrinkle-holding plate 3 in more severe drawing. Further, it is desirable that the plane position to which the hydraulic pressure is applied is not overlapped with the die and the wrinkle holding plate. The pressure of the high-pressure liquid to be added is preferably as high as possible, but may be any pressure higher than a predetermined value that is effective in avoiding wrinkles or breakage. What is necessary is just to select suitably.
Further, the type of the high-pressure liquid used in the present invention does not need to be specified, does not cause a problem such as corrosion or clogging in the supply path of the high-pressure liquid, and does not impair corrosion or degreasing of drawn parts. Any type is acceptable.

Although the details of the present invention have been described above by taking as an example the case of drawing by a double action press machine shown in FIG. 1, the method of the present invention is also applicable to a single action press machine shown as an example in FIG. Any press machine that can perform drawing can be applied. Further, the method of the present invention can be applied to any material that is to be subjected to drawing.

FIG. 6 is a view showing a state in which the workpiece 4 is sandwiched between the die 2 and the wrinkle holding plate 3 when a large number of liquid discharge ports and liquid grooves associated therewith are provided. In FIG.
Reference numeral 15 denotes a liquid discharge port, and 16 denotes a die shoulder.

FIG. 8 shows the limit wrinkle holding force at which breakage or wrinkling begins to occur when a circular plate material is molded by changing the wrinkle holding force in various ways by performing a cylindrical drawing test with the combination shown in FIGS. The figures show the case where the high-pressure liquid is discharged from the liquid discharge ports 11 or 12, the case where the high-pressure liquid is discharged from the liquid discharge ports 13 and 14, and the case where the high-pressure liquid is discharged from the liquid discharge ports 13 and 15, respectively. The left end in the figure is the result of normal molding performed as a comparative example.

Here, as the hydraulic pressure is increased, the wrinkle holding force at the breaking limit can be increased, the breaking prevention ability is excellent, and the range of the wrinkle holding pressure that can be formed is widened. Further, the case where the liquid pressure is applied from both the die and the wrinkle holding plate (the liquid discharge ports 13 and 14) and the case where the liquid pressure is applied only from the die side (the liquid discharge ports 11 or 12) It can be seen that a significant improvement is achieved in the case where the plane position is not the die and the wrinkle holding plate does not overlap (the liquid discharge ports 13 and 15).

Also, in the case where the plane position of the liquid discharge port is not overlapped by the die and the wrinkle holding plate (liquid discharge ports 13 and 15), the higher the liquid pressure is, the more the wrinkles are suppressed. The required limit wrinkle holding force can be reduced, and the wrinkle resistance is excellent. Therefore, both the breaking avoidance ability and the wrinkle resistance are best when the liquid discharge ports are not overlapped by the die and the wrinkle holding plate (the liquid discharge ports 13 and 15).

For example, in FIG. 8 , wrinkles and breakage do not occur in the range of 50 kN or more and 80 kN or less in the normal molding, but when the high pressure liquid is discharged from the liquid discharge ports 13 and 15, the liquid pressure is 3 MPa. Wrinkle holding force spreads in the range of 20 kN or more and 110 kN or less, and further has a liquid pressure of 30 MPa.
Then, the wrinkle holding force is expanded to a range of 20 kN or more and 220 kN or less. Thus, when the processing method of the present invention is applied, it can be seen that wrinkles and breaking limits are significantly improved as compared with the normal molding of the comparative example.

FIG. 7 shows the limit wrinkle holding force at which breakage or wrinkling begins to occur when a circular plate is formed with various changes in wrinkle holding force by performing a cylindrical drawing test using the combinations shown in FIGS. When the liquid pressure is applied only from the die side (liquid discharge port 13), when the liquid pressure is applied only from the wrinkle holding plate side (liquid discharge port 14 or 15), the liquid discharge port is applied from both the die and the wrinkle presser. The case where the plane position is not overlapped with the die and the wrinkle holding plate (the liquid discharge ports 13 and 15) is shown.

FIG. 7 shows that even when the hydraulic pressure is applied only from the wrinkle holding plate side (liquid discharge port 14 or 15), a remarkable effect is recognized as compared with the normal molding of the comparative example, and the hydraulic pressure is applied only from the die side. In the case where the liquid discharge port 13 is added (the liquid discharge port 13), a greater effect is obtained. When the plane position of the liquid discharge port is not overlapped with the die and the wrinkle holding plate from both the die and the wrinkle holder (the liquid discharge ports 13 and 15). ) Indicates that a greater effect can be obtained.

FIG. 9 shows the same cylindrical drawing test in which the present invention is applied to the cylindrical drawing apparatus shown in FIG. 1 when the additional hydraulic pressure is 9.8 MPa, and the conventional ordinary cylindrical drawing shown in FIG. It shows the relationship between the wrinkle holding force and the limit drawing ratio in the case where the forming is performed by the apparatus and in the case where the opposing hydraulic drawing is performed in which the die is a closed mold.

In FIG. 9, for example, when the drawing ratio is 2.0, the range of the wrinkle pressing force at which neither wrinkles nor breakage occurs is 55 k in the opposing hydraulic forming, not in the normal forming.
In the range from N to 80 kN, the method of the present invention
The range is expanded from 0 kN to 165 kN. As described above, according to the method of the present invention, both the wrinkle generation limit and the breaking limit are greatly improved as compared with the normal molding of Comparative Example 1, and are extremely superior to the opposed hydraulic drawing method of Comparative Example 2. I understand.

[0033] FIG. 10 is a combination of the mold shown in drawing devices, and 4 shown in FIG. 2, a square sheet the blank-holding force square tube drawing and the present invention method while varying
And if the angular tube in a conventional ordinary grain Ri processing apparatus shown in FIG. 5
The drawing shows the situation of wrinkles and breaks generated at the corners, the projections generated at the drawn wall at the right side, and the processing flaws generated at the drawn wall at the corners when drawing is performed. In the case of the normal molding of the comparative example, wrinkles or bumps of the drawn wall are generated under low wrinkle holding force conditions, and breakage occurs when the wrinkle holding force is increased to avoid these, and drawing is performed on the corner part drawn wall. It can be seen that flaws have occurred. All of these result in product defects. That is, there is no processing condition for obtaining a product which avoids all these problems at the same time in the ordinary molding method.

On the other hand, when the method of the present invention is applied, by setting the wrinkle holding force to be 40 kN or more and 180 kN or less, any of wrinkles, breaks, bulges of the right-side narrowed wall, and processing flaws of the corner narrowed wall can be obtained. Good drawing of a good product that does not occur can be performed. This is because wrinkles, breakage and processing flaws were avoided by selectively applying the pressurized liquid only to the corners while maintaining the lubrication of the right side portion as it is in order to suppress beveling. .

Further, according to the method of the present invention, since a high-pressure liquid is always interposed between the workpiece and the die or the wrinkle holding plate, the surface-treated steel sheet, the pre-coated material, the aluminum alloy material, the lead, etc. When applied to a material which is liable to cause abrasion on the product surface by the drawing process, the generation of the abrasion can be significantly reduced.

In order to compare the productivity of the method of the present invention and the required press function, the present invention is applied to the cylindrical drawing apparatus shown in FIG. 1 and the conventional ordinary cylindrical drawing apparatus shown in FIG. The working time and the forming force required for working were investigated for the case where the forming was performed and the case where the opposed hydraulic drawing was performed with the die being a closed mold. As a result, 1
Assuming that the average processing time per unit and the forming force were respectively 1, the average processing time of the method of the present invention was about 1.05, and the forming force was about 0.97.

On the other hand, in the counter hydraulic forming, the average processing time was about 3.50, and the forming force was about 2.2. It is clear that the method of the present invention greatly improves both the processing time and the forming force required for the processing as compared with the counter-hydraulic drawing, and is almost the same as the normal forming. That is, the method of the present invention can be applied to a general-purpose press having no special function, and does not impair the productivity.

In the method of the present invention, the step of oiling the plate material before forming can be omitted, and the degreasing step after forming can be omitted depending on the selection of the liquid to be used. Can also be greatly improved.

[0039]

As described above, according to the method of the present invention, a general-purpose press is used without impairing production efficiency.
Wrinkles and breaks can be avoided at the same time, and the frictional force at only the necessary portions can be selectively reduced, so that the drawing workability of the plate material can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a state immediately before drawing when drawing is performed using a double action press according to the method of the present invention.

FIG. 2 is a cross-sectional view showing an example of a state immediately before drawing when a single action press machine is drawn by the method of the present invention.

FIG. 3 is an example of a plan view of a die or a wrinkle holding plate when performing cylindrical molding by the method of the present invention.

FIG. 4 is an example of a plan view of a die or a wrinkle holding plate when a square tube is formed by the method of the present invention.

FIG. 5 is a cross-sectional view showing an example of a state immediately before drawing when a conventional ordinary drawing method is performed.

FIG. 6 is a diagram showing a state in which a workpiece is sandwiched between a die and a wrinkle holding plate when a large number of liquid outlets and associated liquid grooves are provided.

FIG. 7 shows the results of a cylindrical drawing test using the method of the present invention and normal molding.

FIG. 8 shows the results of a cylindrical drawing test using the method of the present invention and normal molding.

FIG. 9 shows the results of a cylindrical drawing test using the method of the present invention, the counter-hydraulic drawing method, and normal molding.

FIG. 10 shows the results of a square tube drawing test by the method of the present invention and normal molding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Punch 2 Die 3 Wrinkle holding plate 4 Workpiece 6 Liquid supply hole 7 Liquid supply device 8 Liquid supply pipe 9 Liquid discharge port 10 Liquid supply groove

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B21D 22/20 B21D 22/22 B21D 24/00 B21D 24/04

Claims (3)

(57) [Claims] 1. A time of drawing forming a plate material, the liquid discharge port provided on part or the entire circumference of the die or the blank-holding plate or die both facing the mold provided with a liquid discharge port
The part facing the liquid discharge port in the other mold is a flat surface
A drawing method for a plate material, wherein drawing is performed while adding a liquid having pressure to the work material held between the die and the wrinkle holding plate from the liquid discharge port . 2. An apparatus for drawing and forming a sheet material,
The liquid discharge port provided on part or the entire circumference of the die or the blank-holding plate or die both, into a mold having a liquid discharge port
A portion of the other mold opposite to the liquid discharge port
A flat surface, and a means for applying a liquid with pressure to the work material held between the die and the wrinkle retainer plate. 3. The apparatus according to claim 2, further comprising a liquid supply groove connected to the liquid discharge port.