JP5414643B2 - Press die and press method using this press die - Google Patents

Description

  The present invention relates to a press die and a press method using the press die.

For example, as a press mold for molding a dome-shaped partition wall (a bowl-shaped press molding material) used for a large pressure vessel or the like, a lower mold on which a flat base material is placed and this lower mold are pressed. A configuration is known in which an upper mold is pressed against a lower mold while the upper mold is relatively rotated around a pressing direction axis (see, for example, Patent Document 1).
In this press mold, the lower mold is provided with a recess corresponding to the shape of the ridge to be obtained, while the upper mold is viewed from the side so as to fit into the recess of the lower mold. Thus, it is a plate-like stamp that exhibits a downwardly convex half-moon shape. In addition, a rotating device for rotating around the pressing direction axis and a pressing device for raising and lowering and pressing the lower die are provided on the upper die. Note that some rotating devices are configured to rotate the lower mold, and in the press mold, the upper mold or the lower mold can be rotated around the pressing direction axis.

  In the pressing method using this press die, the following procedure is performed by alternately driving the rotating device and the pressing device. That is, each time the upper mold is pressed against the lower mold, the upper mold is raised, the upper mold after being raised is rotated by an appropriate amount around the pressing shaft, and then the upper mold is lowered again and pressed against the lower mold. This operation is repeated for a plurality of cycles, and finally, the entire circumference in the recess in the lower mold can be pressed by the lower surface of the upper mold.

JP 54-126665 A

  In the conventional press die as shown in Patent Document 1 and the press method using this press die, when pressing the base material with the upper die, the pressing surface (downward convex meniscus arc surface) A phenomenon has occurred in which the material flow in the direction along the direction differs from the material flow in the direction substantially perpendicular to the pressing surface. Specifically, since the friction coefficient with the base plate is large in the direction along the arc-shaped pressing surface and the friction coefficient with the base plate is small in the direction substantially perpendicular to the pressing surface, the two directions intersecting on the pressing surface of the upper mold There was a phenomenon that the material flow to

  Under such circumstances, the material flow described above spreads in the circumferential direction by repeating the operation cycle of rotating the upper mold after being raised and then pressing the upper mold against the lower mold. The material flow toward the radially outward direction is concentrated at the part corresponding to the center of rotation of the upper mold, and this central part causes local thinning (thinning) compared to other parts. It was. When such local thinning occurs, a shape abnormality occurs in the formed press-molded material, which causes a problem.

  The present invention has been made in view of the above circumstances, and uses a press die and a press die that do not cause local thinning when molding a punch-shaped press molding material. An object is to provide a pressing method.

In order to achieve the above object, the present invention has taken the following measures.
That is, the press die according to the present invention has a lower die on which an original material is placed and an upper die that presses the lower die, and the upper die or the lower die is rotated about a pressing direction axis. After pressing the upper mold against the lower mold, the lower mold is a concave mold capable of forming the bowl shape. The upper mold has a vertical plate shape, and the lower end surface of the upper mold is a convex pressing surface that protrudes toward the mold surface of the lower mold. In addition, a cutout portion that is concave upward is formed in a portion that protrudes downwardly from the convex pressing surface.

The convex pressing surface may be an arc-shaped pressing surface that fits into the concave mold surface.
It is preferable that the width W of the notch satisfies the formula (1).
0.05 × R ≦ W ≦ 0.75 × R (1)
Where R is the radius of curvature of the arcuate pressing surface.

On the other hand, the pressing method according to the present invention is characterized in that a bowl-shaped press-molded material is formed using the press mold described above.
In this case, after forming a bowl-shaped press-molded material by pressing with the press mold, a convex portion bulging upward corresponding to the notch of the upper mold remains on the press-molded material Furthermore, it is good to press the said convex part and level it.

  The press die according to the present invention and the press method using this press die can prevent local thinning from occurring when molding a bowl-shaped press-molded material.

It is a perspective view of the press metal mold | die which concerns on this invention. It is a side view of the press die concerning the present invention. It is the figure which showed the upper metal mold | die of the press metal mold | die which concerns on this invention. (A) is the schematic diagram which showed the material flow which arises in a base material when using the upper metal mold | die (conventional example) which does not comprise a notch part, (b) used the press metal mold | die concerning this invention. It is the schematic diagram which showed the material flow which arises in the original material in the case. It is the figure which showed the experimental result of the material flow at the time of press molding. It is the figure which showed the upper metal mold | die used by another embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 show an embodiment of a press die 1 according to the present invention.
As shown in FIGS. 1 and 2, the press die 1 has a lower die 2 installed on a factory floor and the like, and an upper die 3 provided above the lower die 2. Yes. By pressing the upper mold 3 against the lower mold 2 in a state where the base material 5 is placed on the lower mold 2, the base material 5 is pressed into a bowl-shaped press molding material.

  In addition, the base material 5 employ | adopts the plate-shaped base material provided with the standing rib 5a so that an outer peripheral part may be bordered, the circular board | plate material without the standing rib 5a, etc., for example. As the size of the original plate 5, a diameter (inner diameter in the case of having the standing rib 5a) = 2500 mm or more is assumed. When molding a hard material or a high deformation rate, hot press molding heated to about 700 ° C. to 1250 ° C. may be performed.

The lower mold 2 has a concave mold surface 2a whose upper surface is recessed downward. The mold surface 2a is a space corresponding to a bowl shape, and has a circular shape in plan view and a semicircular side sectional shape.
The upper die 3 can be moved up and down by a press device (not shown) such as hydraulic pressure or water pressure, and a space for taking in and out the base material 5 and the bowl-shaped press molding material can be secured on the upper portion of the lower die 2. It moves up and down between the up position and the down (pressing) position where the lower mold 2 is pressed. Naturally, the upper die 3 can press the lower die 2 with a predetermined pressing force (a rolling force) at the lowered position by this pressing device.

In addition, a rotating device (not shown) that allows the upper mold 3 to rotate by a predetermined angle around an axis with respect to a direction in which the lower mold 2 is pressed is provided on the upper mold 3. The rotation center of the upper mold 3 is matched with the center (circular center) of the mold surface 2a when the lower mold 2 is viewed in plan.
Therefore, by operating this rotating device when the upper mold 3 is in the raised position, it is possible to displace the rotation angle of the upper mold 3 in plan view during pressing every time. Further, by repeating the operation of the rotating device, the rotation angle of the upper mold 3 in plan view can be rotated over 360 ° or more.

  The upper die 3 has a vertical plate shape (a plate shape standing in the vertical direction), and a connecting rod 6 connected to a rotating device and a press device is provided on the upper part. The lower end surface of the upper mold 3 is a convex pressing surface 3 a that protrudes toward the mold surface 2 a of the lower mold 2. The convex pressing surface 3a is an arc-shaped pressing surface that fits the inner peripheral surface of the mold surface 2a when fitted into the mold surface 2a.

In addition, in the upper mold 3, a cutout portion 10 that is concave upward is formed in a portion that protrudes downwardly from the convex pressing surface 3a. The notch 10 penetrates the upper mold 3 in the thickness direction (horizontal direction) in a tunnel shape.
The width W of the notch 10 (the width that opens at the lower end side as shown in FIG. 3) is set to satisfy the formula (1).
0.05 × R ≦ W ≦ 0.75 × R (1)
However, R is the curvature radius of the convex pressing surface 3a.
Here, when the width W of the cutout portion 10 is less than 0.05 × R, it is not possible to prevent local thinning (thinning of the central portion of the press-molded material) that occurs on the inner surface of the press-molded material. It has been confirmed by experiments that when the width W of the cutout portion 10 exceeds 0.75 × R, thinning (thinning) occurs on the outer surface of the press-molded material. More preferably, 0.1 × R ≦ W ≦ 0.7 × R.

Note that the upper mold 3 may be formed such that its upper end portion 13 (in the range of about R / 2 from the center of the radius of curvature R) is linearly formed as a side view shape of the upper mold 3.
Further, it is preferable that the edge portion of the upper mold 3 is formed on the R surface 11 which is all chamfered. Such chamfering is preferably performed on the inside of the notch 10 and formed on the R surface 12.

Furthermore, it has been experimentally confirmed that the upper recess height H of the notch 10 is preferably set to a size satisfying the expression (2).
0.05 × W ≦ H ≦ 0.5 × W (2)
Here, when the dent height H of the notch 10 is less than 0.05 × W, the material present in the notch 10 is reduced (the amount of the original material that can be accommodated in the notch 10 is small). It has been confirmed by experiments that the thickness of the center portion of the press-molded material is reduced and there is almost no effect of preventing the lack of thickness.

Moreover, if the height H of the upper recess of the notch 10 exceeds 0.5 × W, the strength of the upper mold 3 may be significantly lowered, which is not preferable.
Furthermore, it has been confirmed by experiments that the plate thickness t of the upper mold 3 is preferably a size satisfying the expression (3).
R / 16 ≦ t ≦ R / 2 (3)
However, t is the plate thickness at the convex pressing surface 3a (that is, the contact position with the base material 5).
Here, if the plate thickness t of the upper mold 3 is less than R / 16, the upper mold 3 is too thin, and the pressing of the upper mold 3 becomes a high surface pressure, and the base material 5 becomes the upper mold. As a result, the original material 5 cannot be sufficiently reduced.

Further, when the plate thickness t of the upper mold 3 exceeds R / 2, the required rolling force increases as the contact area between the upper mold 3 and the base material 5 increases. There are cases where the over-rolling ability is exceeded (in short, the ability becomes insufficient). Preferably, t = R / 8.
Next, a pressing method for forming a bowl-shaped plate material using the press die 1 according to the present invention will be described.

The upper die 3 is raised by the press device, the upper die 3 is lowered with the heated base material 5 placed on the upper portion of the lower die 2, and the upper die 3 is pressed against the lower die 2. To.
At the initial stage, the base material 5 is pressed by the convex pressing surface 3a of the upper mold 3 so that the base material 5 is recessed (recessed) in the mold surface 2a of the lower mold 2. The mold 3 is raised once. Then, the raised upper die 3 is rotated by a predetermined angle around the axis in the pressing direction by the rotating device, and the upper die 3 is lowered again by the pressing device.

Thereafter, until the base material 5 reaches the bottom of the mold surface 2a of the lower mold 2, the operation of the pressing device and the operation of the rotating device are repeated alternately and the press molding is performed.
When the upper die 3 descends and presses the base material 5 during the pressing, the notch 10 provided on the upper die 3 and the base material 5 are in contact with each other in the convex pressing surface 3a and the base material 5. The pressing force by the notch 10 is smaller than the other parts, and the base material 5 accommodated in the notch 10 is in a state in which the material flow is suppressed.

FIG. 4 is a schematic plan view of the result of examining the material flow occurring in the base material 5. FIG. 4 (a) is a case of a comparative example using an upper mold not having a notch, and FIG. 4 (b) This is the case of the present invention using the upper mold 3 provided with the notch 10. The direction of the arrow in each figure represents the direction of material flow, and the length of the arrow represents the degree (amount) of flow.
As is clear from the comparison between FIG. 4A and FIG. 4B, if the upper mold does not have a notch, there is a region X where the material flow is large near the center of the upper mold. As a result, it is apparent that the thinning (thinning of the central portion of the press-molded material) occurs in the region X where the material flow is large.

On the other hand, if the upper mold 3 has the cutout portion 10, the material flow with small restraint occurs almost uniformly on the side of the upper mold 3 near the center and near the outer periphery. It has become. Therefore, in the punch-shaped press-molded material formed using the press die 1 according to the present invention, local lack of wall does not occur.
In addition, the convex part which protruded upwards corresponding to the notch part 10 of the upper metal mold | die 3 may remain | survive in the press-molded material of the bowl shape formed in this way. Such protrusions may be cut by subsequent machining, but the remaining protrusions may be pressed by a pressing means (not shown) such as a punch to level (crush) the protrusions. .

The results of experiments conducted to determine the dimensions and shape of the press die 1 of the present invention are shown below.
In the experiment, in the upper mold 3, pressing was performed in a state in which the ratio of the convex pressing surface 3 a to the curvature radius R was changed by changing the width W of the cutout portion 10 and the height of the upper recess H in various ways. The correlation between these W and H and the occurrence of undercutting (thinning of the central portion of the press-molded material) was examined.
The base material 5 is a dish-shaped base material made of S45C and provided with standing ribs 5a so as to border the outer periphery.

The outer dimensions (see FIG. 2) of the base material 5 were an outer diameter D of 240 mm, an inner diameter d of 180 mm, an outer peripheral plate thickness h1 of 50 mm, and a plate thickness h2 in the central recess of 25 mm. The base material 5 was heated to 800 ° C. before pressing.
The curvature radius R of the convex pressing surface 3a in the upper mold 3 is 95 mm (that is, the inner diameter of the bowl-shaped plate material formed by pressing is 190 mm), and the plate thickness t of the upper mold 3 is 10 mm (about R / 8).

  Table 1 and FIG.

From Table 1, W / R needs to be 0.05 ≦ W / R ≦ 0.75, and H / W is 0.05 ≦ H / It was confirmed that W ≦ 0.5 is preferable.
Further, FIG. 5 shows the occurrence of undercutting when the ratio between the width W of the notch 10 and the radius of curvature R of the convex pressing surface 3a is changed. It is the graph shown as the coordinate of an inner surface and an outer surface. In this figure, the horizontal axis represents W / R, and the vertical axis represents the position coordinates of the material in the central portion (outer top surface, inner top surface) of the press-molded material.

In the press-molded material shown in FIG. 5, the final shape (the shape after cutting) takes a coordinate value of about 57 on the outer top surface, and the final shape (the shape after cutting) takes a coordinate value on the inner top surface. It takes a value of about 40.
As is clear from this figure, on the outer top surface, when W / R takes a large value, the final position coordinate of the material is lower than the coordinate value (about 57), that is, the outer surface is thinned. You can see that On the other hand, on the inner top surface, when W / R takes a small value, it can be seen that the position coordinate of the material has a final shape exceeding the coordinate value (about 40), that is, the inner surface is thin. That is, if W / R is 0.05 ≦ W / R ≦ 0.75, the lack of product can be prevented. The applicants of the present application have confirmed that lack of thickness can be reliably prevented by more preferably 0.1 ≦ W / R ≦ 0.7.

The present invention is not limited to the above-described embodiment, and can be appropriately changed according to the embodiment.
For example, the upper mold 3 can be formed with a small height as shown in FIG. In addition, the plate thickness t of the upper mold 3 can be formed in a tapered shape (T1> T2). Needless to say, equation (3) is applied, where t is the lower end thickness T2 in this case. By adopting such a taper shape of the lower depression, when the upper die 3 is lifted after the base material 5 is pressed by the upper die 3, the upper die 3 and the base material 5 are separated (releasing properties). ) Is surely and smoothly performed.

In addition, if the upper dent height H in the notch part 10 is made low, it will be added that the notch part 10 becomes a flat shape. However, the cutout portion 10 is not limited to an arc shape, and can be formed as, for example, a polygonal recess.
In the embodiment, the upper mold 3 is described as being rotatable, but the lower mold 2 may be configured to be rotatable. Both the upper mold 3 and the lower mold 2 may be rotated.

The material, shape, dimensions, and the like of the base material 5 are not particularly limited, and the hot pressing is not limited and may be cold.
In this embodiment, the upper mold is rotated about the pressing direction axis after the upper mold is raised during press working. However, the lower mold is rotated about the pressure direction axis. There is no problem.

DESCRIPTION OF SYMBOLS 1 Press die 2 Lower die 2a Mold surface 3 Upper die 3a Convex pressing surface 5 Original material 5a Standing rib 6 Connecting rod 10 Notch part 11 R surface 12 R surface 13 Upper end part

Claims (5)

A lower mold on which an original material is placed and an upper mold for pressing the lower mold, and the upper mold or the lower mold is rotated about a pressing direction axis and then the upper mold is moved to the lower mold. In a press mold that molds the base material into a bowl-shaped press molding material,
The lower mold has a concave mold surface capable of forming the bowl shape,
The upper mold is a standing plate shape, and the lower end surface of the upper mold is a convex pressing surface protruding toward the mold surface side of the lower mold,
A press die characterized in that a notch portion that is concave upward is formed at a portion of the convex pressing surface that projects downward.   The press mold according to claim 1, wherein the convex pressing surface is an arc-shaped pressing surface that fits into the concave mold surface. The press die according to claim 2, wherein the width W of the notch satisfies the formula (1).
0.05 × R ≦ W ≦ 0.75 × R (1)
Where R is the radius of curvature of the arcuate pressing surface.   A press method comprising forming a bowl-shaped press-molded material using the press die according to any one of claims 1 to 3.   After forming a bowl-shaped press molding material by pressing with the press mold, when a convex portion bulging upward corresponding to the notch portion of the upper mold remains on the press molding material, The pressing method according to claim 4, wherein the convex portions are pressed and leveled.