JP4347474B2 - Clamping method of superplastic mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a clamping method for a superplastic molding die. In this document, “mold assembly” refers to stacking the upper mold on the lower mold (or stacking one mold on the other mold), and “clamping” means that the upper and lower molds (or one or the other mold) are separated. This means that the molds are clamped together so that they do not.
[0002]
[Prior art]
When a metal material is plastically processed under a certain condition, an extremely large elongation of 800 to 1000% can appear. This phenomenon is called “superplasticity”, and it is explained that this superplasticity is caused by a grain boundary sliding phenomenon.
[0003]
For example, Japanese Patent Application Laid-Open No. 7-265966 “Superplastic Forming Device” describes a compact device. The outline of this apparatus will be described with reference to the following figure. The code has been newly reassigned.
8 (a) and 8 (b) are configuration diagrams and operation explanatory views of the improved conventional superplastic forming apparatus.
As shown in FIG. 4A, the mold 100 is a three-part mold composed of a lower right mold 101, a lower left mold 102, and an upper mold 103, and has a cavity 104 between the lower right mold 101 and the lower left mold 102. In addition, the upper mold 103 has an air supply pipe 106. 107 (... indicates a plurality, the same applies hereinafter) is a heater, 108 is a clamp. Then, the preformed metal plate 110 is sealed in a mold, heated to a predetermined temperature by the heaters 107... And expanded as indicated by an imaginary line by the pressure of the gas blown from the air supply pipe 106. That is, blow molding is performed.
[0004]
In (b), the upper mold 103 is raised as indicated by the arrow (1), the mold is opened by moving the lower left mold 102 to the left as indicated by the arrow (2), and the molded product is indicated as indicated by the arrow (3). 111 is taken out.
[0005]
[Problems to be solved by the invention]
In the right column, page 18 to line 22 of the above publication, “The upper mold 3 and the lower molds 4 and 5 are thereby hermetically clamped by the clamping means 23 etc. [0041] In this state, the furnace The heater 18 attached to the inner wall of the body 2 is heated to an appropriate temperature together with the metal plate W held in the inside of the mold 1 ”, and has been described with reference to FIG. As before, heating is started after clamping by the clamping means.
[0006]
By this heating, the mold 1 begins to expand thermally. The mold 1 of the above publication employs a structure in which the upper and lower molds 3, 4, 5 are firmly clamped by the clamping means 23 or the like so as not to be displaced from each other due to thermal expansion.
[0007]
However, in recent years, the molded articles to be manufactured have become larger, and the molds for molding have to be enlarged accordingly. In a large molding die, the amount of thermal expansion increases, the clamping means becomes unreasonable in strength, and at the same time, thermal stress also increases in the molding die, which causes generation of thermal deformation of the die. Therefore, there is room for improvement in a clamping device for a superplastic molding die with large thermal expansion.
[0008]
Accordingly, an object of the present invention is to provide a clamping device that can be more adapted to heating accompanying the superplastic forming process.
[0009]
[Means for Solving the Problems]
Claim 1 in order to achieve the above object, the edge of one of upper and lower molds were placed in a straight line at least four clamping means with respect to the center of the edge along the edge, one of said clamping means defined as clamping means arranged closest to the center in the center of the edge, defining a clamp means disposed distant sites the remaining clamping means from the center, fitted with clamping means on edge of the one, likewise, vertical On the other edge of the mold, clamp means arranged at the center of the edge and clamp means arranged at a position far from the center are linear along the edge so that at least four clamp means per one edge are provided. And the clamping means arranged at the center of the edge is set to a predetermined clamping pressure, and the clamping means arranged at a position far from the center is set to zero or the predetermined A step of setting a clamp pressure lower than the lamp pressure, and when the mold temperature approaches the molding temperature and blow molding is started and the mold internal pressure reaches a predetermined pressure, the clamp means arranged at the center is the predetermined clamp The clamping means arranged to maintain the applied pressure and disposed at a position far from the center is a method of clamping the superplastic forming die, comprising the step of switching to the predetermined clamp applied pressure.
[0010]
When the mold is opened when the blank material is introduced, the mold temperature decreases. At this time, the center of the edge is clamped strongly, and the part far from the center is clamped weakly. As a result, the thermal expansion that occurs with the next temperature rise of the mold is released toward a portion far from the center. However, since the clamping force is insufficient in this state, when the mold temperature approaches the molding temperature and the mold internal pressure reaches a predetermined pressure, the part far from the center is also strongly clamped. This can satisfy both of suppressing the generation of thermal stress and sufficiently increasing the clamping force.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIGS. 1A and 1B are a structural view and an operational view (No. 1) of a superplastic forming die according to the present invention.
In (a), a blank material 20 as a superplastic molding material is introduced between the upper mold 11 and the lower mold 13 in the mold open state as indicated by the arrow (1) and placed on the lower mold 13. Then, the upper die 11 is lowered for assembling as indicated by arrows (2) and (2). Then, first, the punch portions 14, 14 hit the blank material 20, and these punch portions 14, 14 begin to bend the blank material 20.
[0012]
(B) shows that the punch parts 14 and 14 have penetrated deeply into the die parts 15 and 15 and formed the blank material 20 into a convex deep dish shape. The steps (a) to (b) are referred to as “pre-bending molding” performed before superplastic forming described later. 21 is the obtained pre-bending molded product.
[0013]
FIGS. 2A and 2B are a structural view and an operational view (No. 2) of a superplastic forming die according to the present invention.
In (a), 30 and 30 are clamping means for clamping the mold by clamping the edges 23 and 23 of the lower mold 13 after overlapping the edges 22 and 22 of the upper mold 11. Then, the upper and lower molds 11 and 13 are heated to 500 ° C. to 600 ° C. by a heating means (not shown), and the pre-bending molded product 21 is swelled with the high pressure gas supplied from the high pressure gas generator 19 until it reaches the molding recess 12. That is, blow molding is performed.
[0014]
In (b), the upper die 11 is raised as indicated by the arrow (3), the blower 18 is started and air is blown out from the air 17 and 17, the molded product 24 is cooled by this air, and is shrunk and separated from the upper die 11. The molded product 24 is extruded from the upper mold 11 with air pressure. As a result, the molded product 24 falls on the arm member 25 in a short time. The molded product 24 can be taken out (dispensed) by moving the arm member 25 as shown by the arrow (5).
.
[0015]
3 is a front view of the clamping means according to the present invention. The clamping means 30 includes an upper claw 31, a lower claw 32, a connecting link 33 spanned between the front parts of the upper and lower claws 31, 32, and an upper claw. The cylinder 34 a is connected to the rear part of the claw 31 with a pin 35, and the hydraulic cylinder 34 is connected to the rear part of the lower claw 32 with a piston rod 34 b with a pin 36. When the piston rod 34b of the hydraulic cylinder 34 is extended, the upper and lower claws 31 and 32 are closed, and when the piston rod 34b is pulled, the upper and lower claws 31 and 32 are opened.
[0016]
FIG. 4 is a plan view of the clamping means according to the present invention. A long pin 37 is passed through the front portion of the upper claw 31 and connecting links 33 and 33 are attached to both ends of the pin 37, and the rear portion of the upper claw 31. It shows that the cylinder 34a is connected via the pins 35 and 35. Reference numeral 39 denotes a pressing surface of the upper claw 31.
[0017]
FIG. 5 is a block diagram of a clamping device for a superplastic molding die according to the present invention. The clamping device 40 includes a plurality of clamping means 30 for clamping the edges of the upper and lower molds 11 and 13. , And the same applies hereinafter), and clamp pressure setting means 42 provided on the clamp means 30... And control for controlling the clamp pressure setting means 42. Part 44.
[0018]
In the embodiment, a total of 16 clamping means 30... The clamp pressure setting means 42... Are means for determining the hydraulic pressure based on an instruction from the control unit 44.
Accordingly, the 16 clamping means 30 can independently set the clamping pressure.
[0019]
Next, the operation of the clamping device for the superplastic molding die having the above-described configuration will be described.
FIGS. 6A and 6B are a layout view and an operation view of the clamping means according to the present invention.
The upper and lower molds 11 and 13 have a rectangular shape in plan view, and each of the four edges is held by four pressing surfaces 39.
For convenience, a total of four pressing surfaces 39 at the center of the upper and lower edges are A (A pressing surface 39), a total of four pressing surfaces 39 at the sides (left and right) are C (C pressing surfaces 39), and a total of four at the center of the left and right edges. The four pressing surfaces 39 are called B (B pressing surface 39), and the four pressing surfaces 39 on the side (up and down) are called D (D pressing surface 39).
[0020]
In FIG. 4A, the A pressing surface 39... And the B pressing surface 39. The C pressing surface 39 ... and the D pressing surface 39 ... are set to zero or a low clamping force.
[0021]
When the upper and lower molds 11 and 13 are heated in this state, the upper and lower molds 11 and 13 are thermally expanded as indicated by the arrows (1) and (2). Since the upper mold 11 and the lower mold 13 are different in weight and internal structure, the expansion speed is different. At this time, if the clamping pressure on the C pressing surface 39... And the D pressing surface 39... Is large, the expansion is restrained, and the upper and lower molds 11 and 13 are forced and the reaction thereof. Thus, an excessive reaction force is applied to the clamping means, which is not preferable.
Therefore, in the present invention, for a while after 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 surface 39... Is kept weak so as not to restrain thermal expansion.
[0022]
(B) is a diagram illustrating the setting of the clamping means when the temperature rises to some extent and high pressure gas is blown between the upper and lower molds 11 and 13 for blow molding, and the mold internal pressure rises to some extent. That is, it shows that the clamp pressure on the C pressing surfaces 39... And the D pressing surfaces 39. The reason is as follows.
[0023]
Reason (1)-If the temperature rises and the upper and lower molds 11 and 13 become high in temperature, the thermal expansion and the difference in thermal expansion that occur thereafter become smaller, and there is no concern that the upper and lower molds 11 and 13 will be forced.
Reason {circle around (2)} When the mold internal pressure increases, a force that cancels the clamping force acts. Therefore, it is possible to increase the clamp pressure on the C pressing surface 39... And the D pressing surface 39. On the contrary, if the clamping pressure on the C pressing surface 39... And the D pressing surface 39.
The above description will be described again based on the graph.
[0024]
FIGS. 7A to 7D are graphs for explaining the clamping method of the superplastic molding die according to the present invention, and the horizontal axes of these graphs are all time.
In (a), the vertical axis indicates temperature, which indicates the temperature of the blank material (superplastic molding material), and starts the temperature rise at the point P1 to warm the blank material to about 600 ° C. (molding temperature).
P1 indicates that the mold temperature has decreased because the mold is opened when the blank material is introduced.
[0025]
In (b), the vertical axis is the pressure inside the mold, and at the point (P2) where the mold temperature approaches the molding temperature, high pressure gas starts to be blown into the mold. The point where this pressure reaches the predetermined pressure Ps is called P3.
[0026]
Here, “the mold temperature approaches the molding temperature” means that the mold temperature reaches a temperature corresponding to 50 to 100% of the molding temperature. If it is less than 50%, the expansion residue is large, and it is difficult to mold. If it is 100%, the residual expansion is preferably zero, but the process time is extended. Therefore, when the mold temperature reaches 50 to 100% of the molding temperature, more desirably 70 to 90%, the temperature at which the mold temperature approaches the molding temperature is referred to.
[0027]
The predetermined pressure Ps is about 50% of the blow molding pressure Pb, but may be selected from the range of 0.2 × Pb ≦ Ps ≦ 0.8 × Pb. In the case of an Al-based superplastic molding material, the blow molding pressure Pb is approximately 1.0 MPa.
[0028]
In (c), the vertical axis indicates the clamp pressure at A and B described in FIG. 6, and at A and B, the pressure is increased at the P1 point, that is, at the start of temperature increase. This high pressure is continued until the molding is completed.
In (d), the vertical axis shows the clamp pressure at C and D described in FIG. 6, and at C and D, the point P1 is zero or low, and the point P3, that is, the in-mold pressure is predetermined. When the pressure Ps is reached, the pressure is switched to a higher clamping force.
[0029]
The clamp pressures of C and D are set to zero or low at the point P1, because the edge of the mold is a continuous body, and the influence of the pressure of A reaches C. As a result, if A is pressed, the portion of C is also pressed although the pressing force is small. Accordingly, the C clamping pressure can be made zero. Since D is the same as C, description thereof is omitted.
[0030]
Between the points P1 and P3 described above, the setting of FIG. 6 (a) is made, and after the point P3, the setting of the clamping pressure at C and D is set halfway, as shown in FIG. 6 (b). Switch.
[0031]
The structure of the clamp means 30 is only an example, and there is no problem changing the structure.
[0032]
【The invention's effect】
The present invention exhibits the following effects by the above configuration.
Claim 1, the edge of one of upper and lower molds were placed in a straight line at least four clamping means with respect to the center of the edge along the edge, the one closest to the center of said clamping means The clamp means disposed at the center of the edge, the remaining clamp means are defined as the clamp means disposed at a location far from the center, and the clamp means is attached to the one edge, and similarly to the other edges of the upper and lower molds, Attaching at least four clamping means per edge so that the clamping means arranged at the center of the edge and the clamping means arranged at a position far from the center are linear along the edge; The clamp means arranged at the center is set to a predetermined clamping force, and the clamping means arranged at a position far from the center is set to zero or lower than the prescribed clamping pressure. And the clamping means arranged at the center maintains the predetermined clamping pressure when the mold temperature approaches the molding temperature and blow molding starts and the mold internal pressure reaches the predetermined pressure. The clamping means arranged at a position far from the center is a method for clamping the superplastic molding die, which comprises the step of switching to the predetermined clamping force, and strongly clamps the center of the edge when the die is cold. Then, by clamping the part far from the center weakly, the thermal expansion that occurs with the temperature rise of the mold is released toward the part far from the center. However, since the clamping force is insufficient in this state, when the mold approaches the molding temperature and the mold internal pressure reaches a predetermined pressure, the part far from the center is strongly clamped. This can satisfy both of suppressing the generation of thermal stress and sufficiently increasing the clamping force.
As a result, damage to the upper and lower molds can be suppressed, the life of the mold can be extended, the weight can be reduced, and a great economic effect can be expected.
[Brief description of the drawings]
FIG. 1 is a structural diagram and action diagram of a superplastic molding die according to the present invention (part 1).
FIG. 2 is a structural diagram and action diagram of a superplastic molding die according to the present invention (part 2).
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 block diagram of a clamping device for a superplastic molding die according to the present invention. FIG. 7 is a graph for explaining a clamping method of a superplastic molding die according to the present invention. FIG. 8 is a configuration of an improved conventional superplastic molding apparatus. Figure and explanation of action [Explanation of symbols]
DESCRIPTION OF SYMBOLS 11, 13 ... Upper mold | type and lower mold | type which comprise a superplastic molding die, 22, 23 ... Upper and lower mold | type edge, 30 ... Clamp means, 31 ... Upper nail | claw, 32 ... Lower claw, 34 ... Hydraulic cylinder, 39 ... Press 40, clamping device, 42 ... clamping pressure setting means, 44 ... control unit, Ps ... predetermined pressure.

Claims (1)

The edge of one of upper and lower molds were placed in a straight line at least four clamping means with respect to the center of the edge along the edge, arranged closest to the center of edge to the center of said clamping means was defined as the clamping means is, stipulates that clamping means disposed distant sites the remaining clamping means from the center, fitted with clamping means on edge of the one,
Similarly, at least four clamping means arranged at the center of the edge and clamping means arranged at a position far from the center on the other edges of the upper and lower molds are linear along the edge. Attaching the clamping means of
Setting the clamping means disposed at the center of the edge to a predetermined clamping pressure, and setting the clamping means disposed at a position far from the center to zero or a clamping pressure lower than the predetermined clamping pressure;
When the mold temperature approaches the molding temperature and the blow molding is started and the mold internal pressure reaches a predetermined pressure, the clamping means disposed at the center maintains the predetermined clamping pressure and is disposed at a position far from the center. The clamping means switching to the predetermined clamping force;
Clamping method of superplastic molding die comprising:

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