JPH07144234A - Method for drawing metal sheet and device therefor - Google Patents

Abstract

PURPOSE:To improve drawability by carrying out drawing while a material to the drawn held between a die and a holddown is added with pressurized liquid from liquid ejecting ports which are provided on a peripheral part or all the peripheral part of the die or holddown or both them. CONSTITUTION:Liquid ejecting ports 9 and liquid supplying grooves 10 are provided on a peripheral part or all the peripheral part of the die 2 or holddown plate 3 or both of them and the material to be drawn which is held between the die 2 and holddown plate 3 is added with pressurized liquid. Since the pressurized liquid is maintained to exist between each surface of the material to be drawn 4 and holddown plate 3, frictional force between each surface of the material to be drawn 4 and the die or the holddown plate is remarkably reduce and occurrence of breaking is avoided. Thus, a wrinkle and breaking are breaking are simultaneously avoided and the frictional force is selectively reduced for the required part using a versatile press machine and without reducing productive efficiency.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In press forming of a plate material, drawing is a frequently used processing method and is applied to many parts from small parts to large parts such as automobile outer plates, sinks and baths.

FIG. 5 shows an example of a conventional ordinary drawing method. In FIG. 5, 1 is a punch, 2 is a die, 3 is a wrinkle holding plate, 4 is a work material, and the punch 1 is pushed in while the work material 4 is held by the die 2 and the wrinkle holding plate 3 with a predetermined force. As a result, the drawing process is performed. However, in the drawing process, wrinkles and fractures often cause problems. In order to suppress the generation of wrinkles, it is necessary to add as much clamping force as possible, but increasing the clamping force inevitably causes an increase in the frictional force between the die and the wrinkle retainer plate, causing the work piece to be processed into the mold. The flow of material is obstructed, which eventually leads to fracture.

On the other hand, when the frictional force between the work material and the die and the wrinkle holding plate is reduced by using a press working oil having good lubricity, it is effective for avoiding breakage, but wrinkles It tends to occur. As described above, in the drawing process, it is difficult to avoid wrinkling and fracture at the same time.
Especially in the drawing process of complicated parts shape, the workability of the work piece is different depending on the part of the molded product.Therefore, the part that is difficult to pull in easily breaks, and the part that is easy to pull in has a shape such as wrinkle or surface strain. The reality is that defects are more likely to occur, and it is difficult to take measures against them.

To solve these problems, the following methods have been conventionally considered. A commonly used method for improving the drawability is a method of molding using a highly viscous press working oil having excellent lubricity.

Further, as a method other than the method of forming using a press working oil, reference 1 [Plasticity and Working, Vol.25, no.284
(1984), p831] and the counter hydraulic restriction method described in Reference 2
[Plasticity and processing, Vol.26, no.288 (1985), p73] has been proposed for the circumferential hydraulic drawing method. The opposed hydraulic drawing method is a processing method in which a work material is narrowed down by using a rigid punch in a mold filled with liquid. The liquid that is an incompressible body flows out from the mold as the punch is pushed, so that the frictional force between the die and the workpiece can be reduced. Further, the peripheral hydraulic drawing method is a method in which the high-pressure liquid generated in the mold is applied as a compressive force to the plate surface of the outer edge of the workpiece through a bypass circuit, based on the counter hydraulic drawing method described above. Is.

[0007]

However, the above-mentioned conventional techniques have the following problems. Use of high-viscosity oil makes it difficult to apply oil before molding and degreasing after molding, resulting in a decrease in productivity. Further, the use of high-viscosity oil deteriorates the working environment of the press, increases the frequency of dust adhesion to the mold or press parts, and may impair the surface quality of the molded product. Even if such a defect is eliminated, there is a limit to the improvement of workability by press working oil, and in the case of severe drawing work, fracture cannot be avoided.

On the other hand, when the counter hydraulic drawing method is applied, the punch is subjected to a load necessary for forming the workpiece,
An extra back pressure load is required to push out the liquid in the mold. This back pressure load is obtained 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 forming load, it has a much larger pressurizing capacity than in ordinary forming. A press machine is required. Also, since it is necessary to supply a large amount of liquid for each processing of each part,
Production efficiency is significantly reduced. Furthermore, the pressure of the liquid that flows out is uniform at any part, and it is difficult to selectively reduce the frictional force only in the part where the work material is difficult to be drawn.

Further, although it is said that the peripheral hydraulic drawing method is more improved in drawing workability, the drawbacks of the counter hydraulic drawing method are directly followed and are not improved. Furthermore, in this circumferential liquid pressure drawing method, it is necessary to take a measure for preventing the outflow of liquid such as a seal over the entire outer circumference of the mold, which makes it difficult to manufacture the mold and causes a new problem of durability.

The present invention overcomes the problems in drawing, uses a general-purpose press machine having no special function or ability, and can prevent wrinkles and breaks at the same time without impairing production efficiency, and (EN) A drawing method and an apparatus for drawing a plate material, which is capable of selectively reducing the frictional force only at a necessary portion and has extremely excellent drawing workability.

[0011]

The above-mentioned problems can be solved by the following means. When drawing and forming a plate material, a pressure is applied to the work material sandwiched by the die and the wrinkle retainer plate from the liquid discharge port provided in part or all of the die of the die and / or the wrinkle retainer plate. A drawing method for a plate material, which is characterized in that drawing is performed while adding a liquid.

In an apparatus for drawing and forming a plate material, a liquid discharge port is provided in a part or the entire circumference of a die and / or a wrinkle holding plate, or both dies, and a workpiece held between the die and the wrinkle holding plate is processed. An apparatus for drawing a plate material, which is provided with means for adding a liquid having a pressure. In the above-mentioned device, a plate material drawing apparatus characterized in that a liquid supply groove connected to a liquid discharge port is provided.

[0013]

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

Further, in order to suppress wrinkles, a liquid having a pressure is applied to the work material from the die and / or the wrinkle hold plate so that the work material is the die or the wrinkle hold plate or the die and the wrinkle hold plate. Since the molding proceeds while being adhered to both of them with a uniform surface pressure, the nonuniformity that is the starting point of wrinkle generation is eliminated, and the substantial wrinkle pressing force increases. Due to the synergistic effect of these two effects, the generation of wrinkles is dramatically suppressed as compared with the case where the work material is simply sandwiched between the die and the wrinkle holding plate. Here, when the plane position of the liquid discharge port is not overlapped with the die and the wrinkle holding plate, the effect is great.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing an example of a state immediately before drawing when a double action press is used by the method of the present invention, and FIG. 2 is a single action press by the method of the present invention. In the case of performing the drawing process, an example of a sectional view of a state immediately before the drawing process is shown, FIG. 3 is an example of a plan view of a die or a wrinkle holding plate when the cylindrical forming is carried out by the method of the present invention, and FIG. It is an example of a plan view of a die or a wrinkle holding plate in the case of forming a rectangular tube.

1 to 4, the same parts as those in FIG. 5 are designated by the same reference numerals and the 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 is 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, and 10 is the die 2 or the wrinkle. The liquid supply groove is 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 with such an apparatus, for example, in the case of the drawing apparatus shown in FIG. 1, the work material 4 is placed on the die 2 and pressed by the wrinkle holding plate 3 to sandwich it. After that, when the punch 1 is lowered and the drawing process is performed, 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 installed in a part or the whole circumference of the die 2 and / or the wrinkle pressing plate 3 or both in the vicinity of the contour line of the mold hole, and the liquid supply groove 10 connected to the liquid discharge port 9
As a result, the drawing process is performed while adding to the work material sandwiched by the die 2 and the wrinkle holding plate 3. As a result, it is possible to simultaneously suppress wrinkles and avoid breakage, and it is possible to easily process a good drawn product without wrinkles or breaks.

At this time, the liquid supply device 7 used in the present invention is
Any device may be used as long as it has a function of controlling the hydraulic pressure and the addition timing, and the details of the mechanism are not limited. Further, the high-pressure liquid is basically added immediately after the work piece 4 is clamped by the die 2 and the wrinkle holding plate 3, but the work piece 4 is
May be added before being sandwiched between the die 2 and the wrinkle retainer plate 3, or may be added at the time when the molding progresses to a certain extent and wrinkles or breaks start to occur. The application location and range of the high-pressure liquid are determined by the arrangement position of the liquid ejection port 9 and the size and shape of the liquid supply groove 10 that distributes the high-pressure liquid applied from the liquid ejection port 9 to a wide area. It is desirable to select it according to the shape and processing form of the processed product.

That is, as the additional position of the high-pressure liquid in the direction perpendicular to the hole contour line (drawing direction) of the die or the wrinkle holding plate, the die or the wrinkle holding plate is arranged near the hole contour line of the die or the wrinkle holding plate in which wrinkles are most likely to occur. Is desirable,
This is also effective for breaking because it facilitates the addition 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 form. For example, in the case of the axially symmetric cylindrical drawing shown in FIG. 3, it is necessary to make the entire circumference uniform processing conditions, and the high-pressure liquid is applied to the entire surface of the workpiece 4 sandwiched by the die 2 and the wrinkle holding plate 3. It is desirable to add.

Further, for example, in the case of the non-axisymmetric square tube drawing process shown in FIG. 4, the processing condition of the corner portion is the most severe processing condition, but conversely, the material inflow is excessive in the straight part, so that the drawing process is restricted. It is easy for a wall to stick. In such a case, it is desirable to add the high-pressure liquid only at the corners of the workpiece 4 sandwiched between the die 2 and the wrinkle holding plate 3.

Further, the high-pressure liquid is sufficiently effective even if it is added to the die 2 or the wrinkle holding plate 3, respectively, but in the more severe drawing process, it is added from both the die 2 and the wrinkle holding plate 3. Moreover, it is desirable that the plane position where the hydraulic pressure is applied is not overlapped with the die and the wrinkle holding plate. The higher the pressure of the high-pressure liquid to be added, the more preferable it is, but it is sufficient if it is a predetermined pressure or more effective for avoiding wrinkles or breakage. It may be selected appropriately.
Further, it is not necessary to specify the type of the high-pressure liquid used in the present invention, problems such as corrosion and clogging do not occur in the supply route of the high-pressure liquid, and corrosion of the drawn parts and degreasing property are not impaired. The type does not matter as long as it is one.

The details of the present invention have been described above with reference to the case of drawing by the double action press machine shown in FIG. 1, but the method of the present invention is also applicable to the single action press machine shown as an example in FIG. Any press machine capable of drawing can be applied. Further, the method of the present invention can be applied regardless of the type as long as it is a material used for 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 outlets and liquid grooves associated therewith are provided. In FIG. 6, 11 to
Reference numeral 15 is a liquid discharge port, and 16 is a die shoulder.

FIG. 7 shows a cylindrical wrinkle test with the combinations shown in FIGS. 1 and 6, and shows the limit wrinkle holding force at which breakage or wrinkling begins to occur when a circular plate material is formed by variously changing the wrinkle holding force. It shows the case where the high-pressure liquid is discharged from the liquid discharge ports 11 or 12, the high-pressure liquid is discharged from the liquid discharge ports 13 and 14, and the high-pressure liquid is discharged from the liquid discharge ports 13 and 15. 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 pressing force at the limit of breaking can be increased, the breaking avoidance capability is excellent, and the range of the wrinkle pressing pressure that can be formed is widened. Further, compared with the case where liquid pressure is applied only from the die side (liquid discharge ports 11 or 12), the case where liquid pressure is applied from both the die and the wrinkle holding plate (liquid discharge ports 13 and 14) It can be seen that a great improvement is achieved when the planar position is not overlapped with the die and the wrinkle retainer plate (liquid ejection ports 13 and 15).

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

For example, in FIG. 7, wrinkles and breakage do not occur within the range of the wrinkle pressing force of 50 kN or more and 80 kN or less in 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 Expands to a range of 20 kN or more and 110 kN or less, and 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, it can be seen that when the processing method of the present invention is applied, wrinkles and fracture limits are significantly improved as compared with normal molding of Comparative Example.

In FIG. 8, a cylindrical drawing test was conducted with the combinations shown in FIGS. 1 and 6, and the limit wrinkle holding force at which breakage or wrinkling began to occur when a circular plate material was formed by variously changing the wrinkle holding force, 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 retainer plate side (liquid discharge port 14 or 15), the liquid discharge port is discharged from both the die and the wrinkle retainer. The drawing shows each of the case where the plane position is not overlapped with the die and the wrinkle holding plate (liquid discharge ports 13 and 15).

From FIG. 8, even when the hydraulic pressure is applied only from the wrinkle holding plate side (the 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. When added (the liquid discharge port 13), a larger effect can be obtained. When the flat position of the liquid discharge port is not overlapped with the die and the wrinkle retainer plate from both the die and the wrinkle retainer (the liquid discharge ports 13 and 15). It can be seen that) has a much larger effect.

In the same cylindrical drawing test, FIG. 9 shows the case where the present invention is applied to the cylindrical drawing apparatus shown in FIG. 1 and the conventional normal cylindrical drawing shown in FIG. The relationship between the wrinkle holding force and the limiting drawing ratio is shown when the molding is performed by the apparatus and when the counter hydraulic drawing is performed with the die being a closed type.

In FIG. 9, for example, when the drawing ratio is 2.0, the range of the wrinkle holding force at which neither wrinkles nor breakage occurs is 55 k in not only normal molding but also opposed hydraulic molding.
While it is in the range of N or more and 80 kN or less, in the method of the present invention, 3
It is expanded to the range from 0 kN to 165 kN. As described above, according to the method of the present invention, both the wrinkle generation limit and the fracture limit are greatly improved as compared with the normal molding of Comparative Example 1, and it is extremely superior to the opposed hydraulic drawing method of Comparative Example 2. I understand.

FIG. 10 shows the results obtained by performing a square tube drawing test with the combinations shown in FIGS. 2 and 4 and using the cylinder drawing apparatus shown in FIG. 1 when forming a square plate with various wrinkle holding forces. When the invention is applied and when the molding is performed by the conventional ordinary cylindrical drawing apparatus shown in FIG. 5, wrinkles and breaks that occur at the corners, and beko and corners that occur at the straight side drawing wall The condition of processing flaws that occur on the diaphragm wall is shown below. In the case of normal molding of the comparative example, wrinkles or bevels of the drawing wall occur under low wrinkle holding force conditions, and if the wrinkle holding force is increased to avoid these, breakage occurs and drawing processing is performed on the corner drawing wall. You can see that the flaw is occurring. All of these become product defects. That is, in the usual molding method, there is no processing condition for obtaining a product in which all of these defects are avoided at the same time.

On the other hand, when the method of the present invention is applied, the wrinkle holding force is set to be 40 kN or more and 180 kN or less, so that wrinkles, breakage, bevel of the narrowing wall on the straight side, and processing flaws on the narrowing wall of the corner part are all generated. It is possible to draw good products that do not occur. This is because generation of wrinkles, breakage and processing flaws was avoided by selectively adding pressurized liquid only to the corners while keeping the lubrication of the straight sides as it is to suppress stickiness. .

Furthermore, according to the method of the present invention, since a high-pressure liquid is always present between the work piece and the die or the wrinkle retainer plate, the surface-treated steel plate, precoat material, aluminum alloy material, lead, etc. When applied to a material that is liable to cause scratches on the product surface by the drawing process, the occurrence of scratches can be significantly reduced.

In order to compare the productivity of the method of the present invention and the required press functional force, 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 processing time and the forming force required for the processing were investigated when the molding was performed and when the counter hydraulic drawing was performed with the die being a closed mold. As a result, 1 in normal molding
When the average processing time and forming force per piece were 1, respectively, 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 apparent that the method of the present invention significantly improves both the processing time and the molding force required for the processing as compared with the counter hydraulic drawing, and is almost the same as the normal molding. That is, the method of the present invention can be applied to a general-purpose press machine having no special function and does not impair its productivity.

Further, in the method of the present invention, the step of applying oil to the plate material before forming can be omitted, and even the degreasing step after forming can be omitted depending on the selection of the liquid to be used, so that the production efficiency and workability are better than in the conventional case. Can be greatly improved.

[0039]

As described above, according to the method of the present invention, a general-purpose press machine is used, and production efficiency is not impaired.
It is possible to avoid wrinkles and fractures at the same time, selectively reduce the frictional force only at the necessary portions, and dramatically improve the drawability of the plate material.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a state immediately before drawing when a drawing is performed using a double action press machine 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 cylindrical molding is performed by the method of the present invention.

FIG. 4 is an example of a plan view of a die or a crease presser plate when square tube molding is performed by the method of the present invention.

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

FIG. 6 is a view showing a state in which a work material is sandwiched between a die and a wrinkle holding plate when a large number of liquid discharge ports and liquid grooves associated therewith are provided.

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

FIG. 8: Cylindrical drawing test results by the method of the present invention and normal molding.

FIG. 9 is a result of a cylindrical drawing test by the method of the present invention, a 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]

 1 Punch 2 Die 3 Wrinkle Holding Plate 4 Work Material 6 Liquid Supply Hole 7 Liquid Supply Device 8 Liquid Supply Pipe 9 Liquid Discharge Port 10 Liquid Supply Groove

Claims (3)

[Claims] 1. When a plate material is drawn and formed, a work piece clamped by a die and a wrinkle holding plate from a liquid discharge port provided in a part or the entire circumference of a die and / or a wrinkle holding plate or both dies. A drawing method for a plate material, which is characterized in that drawing is performed while adding a liquid having pressure to the material. 2. An apparatus for drawing and forming a plate material,
A liquid discharge port is provided in a part or the entire circumference of the die and / or the wrinkle retainer plate, and a means for adding a liquid with pressure to the workpiece sandwiched between the die and the wrinkle retainer plate is provided. An apparatus for drawing a plate material, which is characterized in that 3. The plate material drawing apparatus according to claim 2, further comprising a liquid supply groove connected to the liquid discharge port.