JPH06335738A - Method for taking-out superplastic formed product from mold - Google Patents

Abstract

PURPOSE:To provide a formed product take-out method capable of preventing the occurrence of deformation and flaw of a superplastic formed product and taking out the formed product from a mald within a short time with high releas ing property. CONSTITUTION:After the recessed superplastic formed product 7 is obtained by superplastic-forming a superplastic raw plate 6 by using the mold 11 having a recessed forming part 13, only the formed product 7 is substantially cooled by cooling the inside bottom including the bottom part of the formed goods 7 with a coolant to subject only, the formed product 7 to dimensional shrinkage, then released from the mold 11. The formed product 7 is cooled by using a gas stream or abutting a cooling male mold 21 on the recessed inside surface thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing a superplastic molded product from a mold after superplastic molding. In particular, it relates to a method for efficiently removing a superplastic molded product from a mold in a short time.

[0002]

BACKGROUND OF THE INVENTION Superplasticity means that certain materials, such as aluminum and its alloys, copper and its alloys, stainless steel, titanium and its alloys, have a specific temperature range (aluminum: 400-400) 600 ° C,
Titanium and its alloys: about 850 to 950 ° C., stainless steel: 900 to 1050 ° C.), and a property of showing extremely large elongation (400 to 6000%). Utilizing this property, forming a product with a complicated shape, a deep-drawing product, etc. in a single operation is called superplastic forming.
Gas (eg argon) from one side of the work piece
A method in which pressure is applied and the other surface is pressed against a mold is called superplastic blow molding.

In superplastic molding using a mold, the superplastic molded product may stick to the mold after the molding is completed. This is especially the case when the molded product is large, when the molding gas pressure is high, when the draft is small, and when the molded product has many irregularities and is complicated. When sticking occurs, it is necessary to separate the molded product from the mold. At this time, if the molded product is taken out in a cold state together with the mold, the molded product also has sufficient strength, so that there is no problem in terms of deformation of the molded product. However, from the viewpoint of work efficiency, when continuously performing superplastic forming, it is necessary to wait for the molded product and the mold to cool before taking out the work, because the waiting time and the temperature rise until the next forming process are time-consuming. Therefore, there is a problem that productivity is reduced.

On the other hand, when the molded product is taken out at a high temperature, especially when the superplastic molded product is as thin as 0.5 to 2 mm, the strength of the molded product is not sufficient and the molded product may be deformed when taken out. is there. In particular, when a metal mold is used and the molding gas pressure is high, the superplastic molded product enters fine irregularities (oxide film, cutting marks, etc.) on the mold surface, and the part is removed when taking out. There has been a problem that the superplastic molded article is easily deformed by causing mechanical bonding and partial chemical bonding that cannot be handled by a release agent. Furthermore, since a machine such as a crane is used for a large-sized molded product, this problem becomes more remarkable.

In order to deal with such a problem, Japanese Unexamined Patent Application Publication No.
The following method is proposed in 7-97833.
After superplastic forming a superplastic metal, (a) open the mold to expose a part (outside) of the molded product, and (b) between the wall of the molded product and the wall of the mold in the mold. For a period of time sufficient to shrink the part to the extent that a tighter relationship is obtained, a coolant (air flow) is applied to the exposed part of the part so that the mold itself is substantially affected by this cooling. (C) Molding is performed by a device that discharges the molded product to the outside of the mold by overcoming the holding force that still exists between the wall of the molded product and the mold that is left in the mold. Hitting the article, which does not exceed the elastic limit of the superplastic material, but is about 10
It is carried out at a high enough speed to reach the superplastic material which has been hit with a yield strength equal to 500 kg / cm ² .

[0006]

Problems to be Solved by the Invention JP-A-57-9783
The method No. 3 is noteworthy in that it provides the idea of "cooling and shrinking the superplastic molded product to aid in mold release." However, this method has not solved the following problems. Since it is necessary to expose a part of the molded product to the outside of the molding concave portion of the mold in a manner that makes it easy to blow the air flow, the structure of the mold becomes complicated and the material yield decreases. Since a part of the molded product and only the exposed outside are cooled (air cooling), it is impossible to effectively cool the bottom of the molded product where the bite between the mold and the molded product is the most problematic.

Because of the above, the releasability of the molded product is insufficient, and in order to cope with this, a "device for discharging the molded product to the outside of the mold by hitting" is required to remove the molded product from the mold. It was Since this equipment is exposed to the superplastic forming temperature (800 ° or more in the case of Ti alloy and duplex stainless steel), it requires special consideration and response in designing, manufacturing and maintaining. Due to the above "hit", there is a possibility that the molded product may be damaged or deformed, especially in the case of a large-sized and thin molded product.

According to the present invention, the superplastic molded article has a good releasability,
Provides a method for removing a superplastic molded product from a mold that can prevent deformation and scratches on the superplastic molded product, suppress the mold temperature drop to a minimum, and remove the molded product in a short time. The purpose is to do.

[0009]

Means for Solving the Problems The present inventor has conducted various experiments and searched for the relationship between the releasability of a molded product and a mold. As a result, by making the temperature of the part including the bottom of the superplastic molded product different from the temperature of the mold, a shear force is applied between the superplastic molded product and the mold by utilizing the difference in shrinkage ratio due to the temperature decrease. Then, the inventors have newly found that the two are released, and completed the present invention.

That is, the method for taking out the superplastic molded product of the present invention from the mold is as follows. After the superplastic material original plate is superplastic molded using a mold having a molding recess, a concave superplastic molded product is obtained. A method of removing a superplastic molded product from a mold; the inner surface including the bottom portion of the concave superplastic molded product is cooled by operating a coolant from the inner surface side to substantially cool only the superplastic molded product. It is characterized by shrinking and then separating the superplastic molded product from the mold.

[0011]

[Function] By cooling the inner surface including the bottom of the superplastic molded product, which is the most difficult to cool, directly from the inner surface, only the superplastic molded product can be cooled most effectively. As a result, the dimensional shrinkage of the superplastic molded product can be relatively large. Further, when the bottom portion is dimensionally contracted, the peripheral wall portion is also pulled by the wall portion and tries to move toward the inside of the molding concave portion of the mold. Due to these actions, a shearing force and a tensile force act between the surface of the superplastic molded product and the surface of the mold, and the binding force on both surfaces is eliminated.

The method of the present invention is particularly effective when the thickness of the superplastic material original plate is 2 mm or less. Further, the concave shape of the superplastic molded product is effective when the width is wider (the bottom is wider) compared to the depth, for example, when the width / depth is 2 or more. As the coolant, any of gas, liquid and solid can be applied.

This method is particularly effective when the materials of the superplastic molded product and the mold are the same. For example, there is a case where the duplex stainless steel is used as the superplastic forming material and the heat-resistant steel is used as the mold. When an aluminum alloy is used as a superplastic forming material and a heat-resistant steel is used as a mold, the thermal expansion coefficient is significantly different (aluminum alloy 31 × 10 ^-6 / ° C, heat-resistant steel 17 × 10 ^-6 / ° C) Even when the temperature is lowered by cooling, the amount of shrinkage is greatly different, and as a result, the shear force acts. Even in this case, by forcibly cooling the aluminum alloy of the superplastic molded product, it is possible to take out the product more easily.

For forced cooling, gas blowing is suitable. The type of gas is not particularly limited, and various gases such as air, nitrogen, and argon, and those sprayed with water can be used according to the material and the properties of the molded product.
Furthermore, it is possible to modify the surface of the superplastic molded product by reacting the gas with the superplastic molded product while also serving as cooling. As a method of spraying gas, after superplastic forming, the upper die is moved and a nozzle or the like can be used from above.

In one aspect of the present invention, a low temperature shaped member is brought close to or in contact with the inner surface of the superplastic molded product in order to act the coolant. For example, a copper male mold is formed along the mold with a gap of about 2 mm in the mold. This gap is
The shrinkage allowance of the superplastic molded product is expected (prevents the superplastic molded product from being caught in the male mold and becoming incapable of being taken out). It is decided in consideration of preventing scratches and deformation.

This aspect has the following advantages. It is possible to evenly cool the superplastic molded product, and the shape of the molded product is not destroyed. It is possible to prevent foreign matter from adhering during cooling (for example, in gas cooling, dust and the like around the foreign matter may be caught and adhere to a molded product to deteriorate the surface quality). It should be noted that the inside of the male mold has a water-cooled structure, and after the molded product is taken out, the male mold is cooled during the next molding, whereby the male mold can be repeatedly used.

In one aspect of the present invention, the above-mentioned superplastic molded product has a protrusion at the bottom, and the protrusion is selectively strongly cooled. In the case of a superplastic molded product that has a protrusion, by cooling the periphery of the protrusion, a shearing force can be effectively applied between the mold and the protrusion, and this force can separate the mold and the molded product. it can.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given below with reference to the drawings and experimental results. FIG. 1 is a diagram showing a method of taking out a superplastic molded product in an embodiment using a fixed member (cooling male mold) for cooling the inner surface of the superplastic molded product. (A) shows a state where the molding is completed and the top plate is moved. (B) shows a state where the cooling male die is applied to the molded product to cool the molded product. (C)
Shows a state in which the molded product is lifted together with the cooling male mold.

In FIG. 1, the mold 11 has a molding recess 13 having a shape corresponding to a desired shape of the molded product. Molding recess 1
Around the circumference of 3, a flange-shaped holding portion 15 is provided. The superplastic original plate 6 is placed on the sandwiching portion 15, and the peripheral portion of the original plate 6 is sandwiched by being pushed from above by the sandwiching portion 5 on the peripheral edge of the top plate 1. At the stage where the original plate 6 is soaked to the superplastic forming temperature,
Ar gas is introduced into the space on the upper surface of the original plate 6 in the top plate through an Ar gas introduction hole 3 formed in the center of the top plate 1. A
The original plate 6 is projected downward by the pressure of the r gas, and finally is superplastic blow-molded into a shape in which it is in close contact with the molding recess 13 of the mold 11.

In this state, the original plate 6 becomes a molded product 7. Of the molded product 7, the concave bottom portion pressed against the bottom surface of the molding recess 13 of the mold 11 is the bottom portion 8, and the peripheral flange-shaped portion clamped by the clamping portion 15 of the mold is the flange portion 10 and the flange portion 10. The hanging portion from the bottom to the bottom 8 is referred to as a wall 9.

In FIG. 1B, the cooling male die 21 is introduced to the upper surface (inner surface) of the molded product 7 after the top plate 1 of FIG. 1A is removed. The cooling male die 21 is made of copper and is cooled by water flowing through the internal flow path. The lower part of the cooling male mold 21 has a convex shape corresponding to the inner surface shape of the molded product 7, and when the cooling male mold 21 is introduced into the molded product 7, the cooling male mold 21
The lower surface and the inner surface (upper surface) of the molded product 7 are in contact with each other. For this reason, heat is taken from the molded product 7 due to radiation and conduction, and the temperature of the molded product 7 rapidly decreases. As a result, the molded product 7 shrinks in dimension, and the inner surface of the molded product 7 and the mold 1
1 Shear / tensile force is generated between the surface of the molding recess 13 and
Both surfaces are easy to separate.

Claws 25 for hooking the flange portion of the molded product 7 are provided on the periphery of the cooling male die 21. Claw 25
Can be swung about a rotation fulcrum 27 attached to the cooling male die 21. The claw 25 is U-shaped and has a sharp tip. The tip of this claw is attached to the flange portion 10 of the molded product 7 and the holding portion 15 of the mold 11.
The molded product 7 can be held by the cooling male mold 21 by inserting the molded product 7 into the cooling male mold 21. As it is, Fig. 1 (C)
As shown in, if the cooling male mold 21 is lifted,
The molded product 7 can be taken out of the mold 11 together with the cooling male mold 21. When performing gas cooling, create a lifting ring corresponding to the shape of the flange portion 10 of the molded product 7,
Claws can be attached to this.

FIG. 2 is a diagram showing an embodiment of an effective cooling method for a molded product having a protrusion on the bottom. At the bottom of the molded product 41, a protrusion 43 (a camel's bump-shaped protrusion) is formed. In such a case, if the protruding portion and further the peripheral portion thereof are selectively strongly cooled, the releasability is good. In this embodiment, the gas blown out from the cooling gas nozzle 47 is blown against the inner surface of the protrusion 43 to cool it. The nozzle 47 is arranged at a predetermined position of the cooling head 45, and by appropriately positioning the header 45 with respect to the mold 31, the nozzle 47 and the molded product projecting portion 43 can be aligned with each other. .

Hereinafter, examples in which the method of the present invention is carried out (Examples (A) and (B)) will be described. Example (A) Superplastic forming was performed under the following conditions. Superplastic forming material: Duplex stainless steel (25Cr-6Ni-3
Mo), plate thickness 0.5 mm Upper mold: Heat resistant steel (equivalent to SUS310) Lower mold: Heat resistant steel (equivalent to SUS310) Lifting ring: Heat resistant steel (equivalent to SUS310) Thickness 50
mm Superplastic forming conditions Temperature: 980 ° C Gas: Ar Gas pressure: 21Kg / cm ² After superplastic forming, move the upper mold and use the air nozzle (pressure 6Kg / cm ² ) from above to form the wall of the molded product. Air was blown on the bottom for 10 seconds. At this time, the temperature of the superplastic molded product was lowered to 900 ° C, and the temperature of the lower mold was 980 ° C, which was not decreased. As a result, the superplastic molded product and the mold could be easily separated.

Example (B) Superplastic forming was carried out under the following conditions. Superplastic molding material: Aluminum alloy (5083A equivalent), plate thickness 1.0mm Upper mold: Heat resistant steel (SUS310 equivalent) Lower mold: Heat resistant steel (SUS310 equivalent) Superplastic molding conditions Temperature: 500 ° C Gas: Ar Gas pressure: 15Kg After the completion of / cm ² superplastic forming, the upper mold was moved, and an internal water-cooled copper male mold was placed from above to absorb the heat of the molded product for 3 seconds.
At this time, the temperature of the molded product is 400 ° C and the temperature of the lower mold is 480.
The temperature was lowered to ℃, and the superplastic molded product and the mold could be separated easily.

[0026]

As is apparent from the above description, the method for removing the superplastic molded product from the mold of the present invention exhibits the following effects. Since the superplastic molded product can be taken out in a short time without substantially lowering the mold temperature, it is possible to remarkably improve the production efficiency when continuously molding. Since the superplastic molded product has good releasability, the molded product can be taken out without applying excessive force or impact to the superplastic molded product. Therefore, it is possible to prevent the molded product from being deformed or damaged.

[Brief description of drawings]

FIG. 1 is a diagram showing a method of taking out a superplastic molded product in an embodiment using a fixed member (cooling male mold) for cooling the inner surface of the superplastic molded product. (A) shows a state where the molding is completed and the top plate is moved. (B) shows a state where the cooling male die is applied to the molded product to cool the molded product. (C)
Shows a state in which the molded product is lifted together with the cooling male mold.

FIG. 2 is a diagram showing an example of an effective cooling method for a molded product having a protrusion on the bottom.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Top plate 3 Ar gas introduction hole 5 Clamping part 6 Original plate 7 Molded product 8 Bottom part 9 Wall part 10 Flange part 11 Mold 13 Molding recessed part 15 Clamping part 21 Cooling male mold 23 Convex part 25 Claw 27 Rotating fulcrum 31 Type 41 Molded product 43 Protruding part 45 Cooling header 47 Cooling gas nozzle

Claims (5)

[Claims] 1. A method for producing a concave superplastic molded product by superplastically molding a superplastic material original plate using a mold having a molding recess, and then removing the superplastic molded product from the mold; By cooling the inner surface including the bottom of the plastic molded product from the inner surface side, substantially only the superplastic molded product is cooled to cause dimensional shrinkage, and then the superplastic molded product is separated from the mold. And a method for removing a superplastic molded product from a mold. 2. The method for removing a superplastically molded product from a mold according to claim 1, wherein the method of applying the coolant is by blowing gas. 3. The method for taking out a superplastic molded product from a mold according to claim 1, wherein the method of applying the coolant is to bring a low temperature shaped member close to or in contact with the inner surface of the superplastic molded product. 4. A hoisting means for hoisting a flange portion of a superplastic molded product is provided on a peripheral portion of the fixed member, and an operation of separating the superplastic molded product from a mold by using the lifting means is included. The method for removing the superplastic molded product according to claim 3 from the mold. 5. The method for removing a superplastic molded product from a mold according to claim 1, wherein the superplastic molded product has a projecting part at the bottom, and the projecting part is selectively strongly cooled.