JP2001137967A - Clamp method of die for superplasticity forming - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology to preferably clamp a die for superplasticity forming. SOLUTION: In figure (a), in die clamping, the A pressing faces 39... and the B pressing faces 39... shown in black colored are set to high clamp force, the C pressing faces 39... and the D pressing faces 39... shown in void are set to low clamp force. A figure (b) shows setting of a clamp means when heating is progressed somewhat, a high pressure gas is blown between upper/ lower dies 11, 13 for blow forming and a die inside pressure is increased somewhat, that is, the clamp force at the C pressing faces 39... and the D pressing faces 39... apart from the center are increased, the whole A-D pressing faces 39 are strongly pressed. Thus, both of the suppression of generation of thermal stress and the sufficient increase of die clamp force are satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for clamping a superplastic forming die. In this document,
"Mold combination" refers to stacking the upper mold on the lower mold (or stacking one mold on the other mold), and "mold clamping" refers to the molds being separated from each other so that the upper and lower molds (or one or the other mold) do not separate. Is to be tightened with a clamp or the like.

[0002]

2. Description of the Related Art When a metal material is subjected to plastic working under certain conditions, an extremely large elongation of 800 to 1000% can be obtained. This phenomenon is called "superplasticity"
It is described that this superplasticity is due to the grain boundary sliding phenomenon.

For example, Japanese Patent Application Laid-Open No. 7-265966 entitled "Superplastic Forming Apparatus" describes a compact apparatus. The outline of this device will be described with reference to the following figure. Note that the reference numerals have been newly re-assigned. FIGS. 8 (a) and 8 (b) are a configuration diagram and an operation explanatory diagram of an improved conventional superplastic forming apparatus. (A)
As shown in the figure, the molding die 100 includes a lower right die 101, a lower left die 1
02, a three-segment type consisting of an upper die 103, and a lower right die 10
1 has a cavity 104 between the lower mold 102 and an upper mold 103 has an air supply pipe 106. (... denotes a plurality, the same applies hereinafter) denotes a heater, and 108 denotes a clamp. Then, the preformed metal plate 110 is sealed in a mold, heated to a predetermined temperature by the heaters 107, and expanded by the pressure of the gas blown from the air supply pipe 106 as indicated by imaginary lines. That is, blow molding is performed.

[0004] In FIG.
3, the mold opening is performed by moving the lower left mold 102 to the left as shown by the arrow, and the molded article 11 is made as shown by the arrow.
Take out one.

[0005]

In the above publication, page 5, right column, line 18 to line 22 states, "The upper mold 3 and the lower mold 4,
5 is hermetically clamped by the clamp means 23 and the like.
[0041] In this state, the mold 1 is heated to an appropriate temperature together with the metal plate W held therein by the heater 18 attached to the inner wall of the furnace body 2. As described with reference to FIG. 8A, heating is started after clamping by the clamping means.

Due to this heating, the mold 1 begins to thermally expand. In the molding die 1 of the above publication, the upper and lower dies 3, 3
A structure is adopted in which the clamps 4 and 5 are firmly clamped by the clamp means 23 or the like so as not to be displaced from each other.

However, in recent years, molded articles to be manufactured have become large, and accordingly, molding dies must be enlarged. In a large molding die, the amount of thermal expansion increases, and the clamping means is unreasonably hardened. At the same time, the thermal stress also increases in the molding die, which is a cause of thermal deformation of the die. Therefore, there is room for improvement in a clamping device for a superplastic forming mold having a large thermal expansion.

Accordingly, an object of the present invention is to provide a clamping device which can be more adapted to heating accompanying the superplastic forming step.

[0009]

In order to achieve the above object, a first aspect of the present invention is a step of attaching a plurality of clamping means to each edge of the upper and lower molds, and a step of mounting the clamping means disposed substantially at the center of the edge by a high clamp. Setting the pressing force to zero or lower the clamping means disposed at a position far from the center to a zero or low clamping force; and, when the mold temperature approaches the molding temperature and starts blow molding, the internal pressure of the mold reaches a predetermined pressure. A step of changing the setting of a part of the clamping force so as to increase the clamping force of the clamping means which has been set to the zero or low clamping force when the pressure has reached zero. is there.

When the mold is opened when the blank material is charged, the mold temperature decreases. At this time, the center of the edge is strongly clamped, and a portion far from the center is weakly clamped.
As a result, the thermal expansion that occurs with the temperature rise of the mold is released to a portion far from the center. However, since the mold clamping force is insufficient in this state, when the mold temperature approaches the molding temperature and the mold internal pressure reaches a predetermined pressure, a portion far from the center is strongly clamped. Thus, both the suppression of the generation of thermal stress and the sufficient increase of the mold clamping force can be satisfied.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 (a) and 1 (b) are a structural diagram and an action diagram (part 1) of a superplastic forming die according to the present invention. In (a), the upper mold 11 and the lower mold 13 are opened.
In the meantime, a blank material 20 as a superplastic molding material is put in as indicated by an arrow, and placed on the lower mold 13. And the arrow,
The upper mold 11 is lowered for mold assembly as shown in FIG. Then, first, the punch portions 14 hit the blank 20, and the punches 14 start bending the blank 20.

FIG. 2B shows that the punch portions 14, 14 have penetrated deeply into the die portions 15, 15, and formed the blank material 20 into a deep dish shape protruding upward. The steps (a) and (b) are referred to as “preliminary bending” performed before superplastic forming described below. Reference numeral 21 denotes the obtained pre-bent product.

FIGS. 2 (a) and 2 (b) are structural views and action diagrams (part 2) of the superplastic forming die according to the present invention. (A)
In the figures, reference numerals 30 and 30 denote clamping means for clamping the upper mold 11 by overlapping the margins 23 of the lower mold 13 on the margins 22 thereof. Then, the upper and lower dies 11 and 13 are heated to 500 ° C. to 600 ° C. by a heating means (not shown), and the high-pressure gas supplied from the high-pressure gas generator 19 expands the pre-bent molded product 21 until it reaches the molding recess 12. That is, blow molding is performed.

In (b), as shown by the arrow, the upper mold 11
, The blower 18 is started, and air is blown out from 17, 17, and the molded product 24 is cooled and shrunk by the air, and
1 and the molded product 24 is compressed by air pressure into the upper mold 1
Extrude from 1. As a result, the molded product 24 falls to the arm member 25 in a short time. By moving the arm member 25 as shown by the arrow, the molded product 24 can be taken out (discharged). .

FIG. 3 is a front view of the clamp means according to the present invention. The clamp means 30 comprises an upper claw 31 and a lower claw 32.
And a connecting link 33 extending between the front portions of the upper and lower claws 31 and 32, and a cylinder 34 a connected to the rear portion of the upper claw 31 with a pin 35, and a piston rod 34 b connected to the rear portion of the lower claw 32.
And a hydraulic cylinder 34 connected by a pin 36.
If the piston rod 34b of the hydraulic cylinder 34 is extended, the upper and lower claws 31, 32 are closed, and the piston rod 3
By pulling 4b, the upper and lower claws 31, 32 are opened.

FIG. 4 is a plan view of the clamping means according to the present invention, in which a long pin 37 is passed through the front part of the upper claw 31, and connecting links 33, 33 are attached to both ends of the pin 37.
And that the cylinder 34a is connected to the rear portion of the upper claw 31 via the pins 35. 39 is a pressing surface of the upper nail 31.

FIG. 5 is a block diagram of a clamping device for a superplastic forming die according to the present invention. The clamping device 40 comprises a plurality of clamping means 30 for clamping the edges of the upper and lower dies 11, 13. .. Indicate a plurality. The same applies hereinafter.), Clamp force setting means 42 provided on each of these clamp means 30.
.. Are controlled by the control unit 44.

In the embodiment, a total of 16 clamping means 30 arranged on four sides × 4 are arranged. The clamping force setting means 42... Are means for determining the oil pressure based on an instruction from the control unit 44. Therefore, the 16 clamping means 30 ...
Can independently set the clamp pressure.

The operation of the clamping device for a superplastic forming die having the above-described structure will be described below. FIG. 6 (a), (b)
FIG. 4 is an arrangement diagram and an operation diagram of a clamp means according to the present invention.
The upper and lower dies 11, 13 have a rectangular shape in plan view, and four edges are suppressed by four pressing surfaces 39, respectively. For convenience, a total of four pressing surfaces 39 at the center of the upper and lower edges are A (A pressing surface 39), and a total of four pressing surfaces 39 on the side (left and right) are C (C pressing surface 39).
A total of four pressing surfaces 39 at the center of the left and right edges are B (B pressing surface 3
9), and a total of four pressing surfaces 39 on the sides (upper and lower) are referred to as D (D pressing surface 39).

Then, in FIG.
A pressing surfaces 39... And B indicated by black rectangles
The pressing surfaces 39... Are set to a high clamping force, and the C pressing surfaces 39... And D pressing surfaces 39... .

When the upper and lower dies 11, 13 are heated in this state, the upper and lower dies 11, 13 thermally expand as shown by arrows. Since the upper mold 11 and the lower mold 13 have different weights and different internal structures, the expansion speed differs. At this time, if the clamp pressing force on the C pressing surface 39... And the D pressing surface 39.
13 is not easy, and an excessive reaction force is applied to the clamping means by the reaction thereof, which is not preferable. Therefore, in the present invention, for a while after the mold clamping, the A pressing surfaces 39... And B pressing surfaces 39... At the center of each edge are strongly suppressed, but the C pressing surfaces 39. The pressing surfaces 39... Are weakly suppressed so as not to restrain the thermal expansion.

(B) shows that the temperature rise proceeds to some extent, and high-pressure gas is blown between the upper and lower dies 11 and 13 for blow molding.
It is a figure explaining the setting of the clamp means at the time when the mold internal pressure rises to some extent. That is, the clamping force on the C pressing surfaces 39... And the D pressing surfaces 39... Far from the center is increased, and all the A to D pressing surfaces 39. The reason is as follows.

Reason: When the temperature rises and the upper and lower dies 11 and 13 become high in temperature, the thermal expansion and the difference in thermal expansion that occur thereafter become small, and there is no fear that the upper and lower dies 11 and 13 will be forced. Reason-When the mold pressure increases, a force acts to offset the clamping force. Therefore, C pressing surface 39... And D pressing surface 39.
························································································ No increase. Conversely, if the clamping pressure on the C pressing surfaces 39 ... and the D pressing surfaces 39 ... is small, the blank material moves inconveniently, so it can be said that it is necessary to increase the clamping pressure. The above description will be described again based on the graph.

FIGS. 7 (a) to 7 (d) are graphs for explaining the method of clamping a superplastic forming die according to the present invention, and the horizontal axis of these graphs is time. In (a), the vertical axis indicates the temperature and indicates the temperature of the blank material (superplastic molding material). The temperature is increased at point P1 to warm the blank material to about 600 ° C. (forming temperature). At point P1, the mold is opened when the blank material is loaded.
Indicates that the mold temperature has dropped.

In (b), the vertical axis is the in-mold pressure,
At a point (P2) where the mold temperature approaches the molding temperature, high-pressure gas is started to be blown into the mold. The point at which this pressure reaches the predetermined pressure Ps is called P3.

Here, "the mold temperature approaches the molding temperature"
"When the mold temperature reaches a temperature corresponding to 50 to 100% of the molding temperature." If it is less than 50%, the residual expansion is large, and the mold and the like are unreasonable. If it is 100%, the residual expansion is zero, which is preferable, but the process time is extended. Therefore, the mold temperature is 50 to 100% of the molding temperature, more preferably 7%.
The time when the temperature reaches 0 to 90% is referred to as the temperature at which the mold temperature approaches the molding temperature.

The predetermined pressure Ps is equal to the blow molding pressure P
b is about 50%, but 0.2 × Pb ≦ Ps ≦ 0.8
It may be selected from the range of × Pb. In the case of an Al-based superplastic molding material, the blow molding pressure Pb is approximately 1.0 M
Pa.

In (c), the vertical axis represents A, A described in FIG.
B shows the clamping force in B, and A and B show the P1
A point, that is, a high pressure is applied at the start of the temperature rise. And this high pressure is continued until the molding is completed. In FIG. 6D, the vertical axis indicates the clamping force at C and D described in FIG. 6. In C and D, the P1 point is set to zero or a low clamping force, and the P3 point, that is, the in-mold pressure is a predetermined value. When the pressure Ps is reached, the pressure is switched to a higher clamping force.

The reason why the clamp pressures of C and D are set to zero or a low pressure at the point P1 is that the periphery of the mold is a continuous body, and the influence of the pressure of A also affects C. As a result, A
By pressing, the pressing force is small, but the point C is also pressed. Therefore, it is possible to make the clamp pressure of C zero. D is the same as C and will not be described.

The setting of the clamp pressure in C and D is as shown in FIG. 6A between the points P1 and P3, and as shown in FIG. 6B after the point P3. Is switched on the way.

The structure of the clamp means 30 is merely an example, and the structure may be changed.

[0032]

According to the present invention, the following effects are exhibited by the above configuration. Claim 1 is a step of attaching a plurality of clamp means to each edge of the upper and lower molds, and setting the clamp means disposed substantially at the center of the edge to a high clamping pressure and disposing the clamp means disposed at a position far from the center. A step of setting the clamping force to zero or low, and a step of setting the clamping means to the zero or low clamping force when the mold temperature approaches the molding temperature and the blow molding is started and the mold internal pressure reaches a predetermined pressure. A step of changing the setting of a part of the clamping force so as to increase the clamping force, and a method of clamping a superplastic forming mold, comprising strongly clamping the center of the edge when the mold is at a low temperature. By weakly clamping the part far from the center, the thermal expansion caused by the temperature rise of the mold is released toward the part far from the center. However, since the mold clamping force is insufficient in this state, when the mold approaches the molding temperature and the mold internal pressure reaches a predetermined pressure, a portion far from the center is strongly clamped. Thus, both the suppression of the generation of thermal stress and the sufficient increase of the mold clamping force can be satisfied. As a result, damage to the upper and lower molds can be suppressed, the life of the molds can be prolonged, the weight can be reduced, and great economic effects can be expected.

[Brief description of the drawings]

FIG. 1 is a structural diagram and an action diagram (part 1) of a superplastic forming die according to the present invention.

FIG. 2 is a structural diagram and an action diagram (part 2) of a superplastic forming mold according to the present invention.

FIG. 3 is a front view of the clamping means according to the present invention.

FIG. 4 is a plan view of the clamping means according to the present invention.

FIG. 5 is a configuration diagram of a clamping device for a superplastic forming mold according to the present invention.

FIG. 6 is an arrangement diagram and an operation diagram of a clamp means according to the present invention.

FIG. 7 is a graph for explaining a method for clamping a superplastic forming die according to the present invention.

FIG. 8 is a configuration diagram and operation explanatory diagram of an improved conventional superplastic forming apparatus.

[Explanation of symbols]

11, 13 ... Upper and lower molds constituting a superplastic forming mold,
22, 23 ... the edges of the upper and lower molds, 30 ... clamping means, 31
... Upper jaw, 32 ... Lower jaw, 34 ... Hydraulic cylinder, 39 ... Pressing surface, 40 ... Clamping device, 42 ... Clamping force setting means, 44 ... Control unit, Ps ... Predetermined pressure.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jiro Watanabe 1-10-1, Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. (72) Ryoichi Kageyama 1-10-1, Shinsayama, Sayama City, Saitama Prefecture Within Da Engineering Co., Ltd. (72) Inventor Hiroyuki Okunaka 1-10-1, Shinsayama, Sayama-shi, Saitama F-term within Honda Engineering Co., Ltd. (reference) 4E050 EA07

Claims (1)

[Claims] 1. A step of attaching a plurality of clamping means to each edge of the upper and lower molds, and setting the clamping means disposed substantially at the center of the edge to a high clamping force, and disposing the clamping means disposed at a position distant from the center. A step of setting the clamping force to zero or low, and a step of setting the clamping means to the zero or low clamping force when the mold temperature approaches the molding temperature and the blow molding is started and the mold internal pressure reaches a predetermined pressure. A step of changing a setting of a part of the clamping force so as to increase the clamping force.