JPS59225824A - Bending method using shape memory alloy - Google Patents

Abstract

PURPOSE:To bend easily a pipe and shape material on site by memorizing the desired mold shape prior to working of a work and during heating thereof to a working die consisting of a shape memory alloy, restraining the work in said die and applying a prescribed temp. change thereto. CONSTITUTION:A working die B to be used for bending of an Alpipe A is constituted of a shape memory alloy of Cu-Zn-Al and a shape is so memorized to the die B that the die is linear at a temp. T0 (ordinary temp.) and takes an arc shape at a temp. T1 (about 70 deg.C). A pipe A is restrained in the die B at the temp. T0 then the temp. of the die B is changed to T1 and the pipe A is bent, by which the temp. of the die B is changed to the intermediate temp. T2 (about 65 deg.C) of T0 and T1 and the pipe A is removed from the die B. The amt. of a spring-back after removal of the pipe A from the die is taken into consideration for the shape of the die B. The die B to be used may be made splittable to plural parts. The easy bending of the pipe and shape material at the end of site is thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to bending, and in particular to bending of rod-shaped materials such as pipes and shapes made of metal materials such as aluminum and copper using a shape memory alloy processing die. Concerning a method of bending.

(Technical background) Shape memory alloys were first announced in 1953.
It is known that even if u-Cd alloy is deformed, it remembers its shape before deformation and has a shape memory effect, returning to its original shape when a slight temperature change is applied. Then in 1963 Tl-N
Although the i-alloy has been put into practical use, it has the drawbacks of being expensive and difficult to process. In 1979, Cu-
Zn-At type shape memory alloys have been announced. This alloy is less expensive than Ti--Ni alloy, and can be easily processed by extrusion, rolling, etc.

The most important feature of Cu-Zn-At type shape memory alloys when applied to mechanical parts is their reversibility. That is, this alloy memorizes different shapes above and below the transformation temperature, and when this alloy is heated or cooled to above and below the transformation temperature, it reversibly deforms into each shape, that is, it exhibits thermoelastic shape deformation. The inventor of the present application has developed the above Cu-Zn-A
, focused on the excellent properties of the alloy, and invented the use of it in bending molds for pipes, profiles, etc. as mentioned above.

(Prior art and problems) Conventionally, in order to bend this kind of bar-shaped material, a bending machine equipped with a roll having a curved surface to be processed is used, and the bar-shaped material is mechanically pressed against the roll. It is known to do so. However, the bending machine requires a mold and a device for operating the mold, making the entire machine relatively large and requiring time and effort to process. Therefore, although it is suitable for large-volume processing in a factory, it is unsuitable for easily performing small-scale bending processing at a terminal location such as on-site or at a retail store.

For this reason, research has been conducted into easy-to-use devices that can be used in the field, but nothing satisfactory has yet been achieved.

(Object of the Invention) The object of the present invention is to eliminate the above-mentioned drawbacks of the conventional method by using a processing die made of a shape memory alloy, and to easily perform bending of pipes, shapes, etc. at the end location. be.

(Structure of the Invention) The gist of the first invention of the present application to achieve the above object is that the shape of the workpiece A to be bent is kept at a predetermined temperature T. The temperature is set to T while the workpiece A is memorized into a mechanically restrained shape and restrained. When changing to T1, the shape memory is stored in a shape that is mechanically restrained to the workpiece A' in a shape that takes into account the amount of springback after demolding to the shape of the workpiece A after processing. Temperature T is applied to processing mold B made of an alloy. After the workpiece A is restrained at T1, the temperature of the workpiece B is changed to T1 to bend the workpiece A, and then the temperature of the workpiece B is changed to T1. The present invention is a bending method using a shape memory alloy, in which a workpiece A is taken out from a working die B at a temperature T2 intermediate between temperatures T1 and T1.

Further, the gist of the second invention of the present application for facilitating demolding is to bend the workpiece A to be bent at a predetermined temperature T.
. If the shape of the workpiece A is memorized in a mechanically restrained shape and the temperature is changed from To to Tt while the workpiece A is restrained, the shape of the workpiece A after being machined will be the same after demolding. The workpiece is placed into a processing die B made of a shape memory alloy that can be divided into a number of parts in which a shape that mechanically restrains the workpiece A is memorized in a shape that takes into account the amount of sgelling pack. A is restrained, and then the temperature of the processing die B is changed to T, and the workpiece A is subjected to bending, and then the processing die B is divided into a plurality of parts and the workpiece B is separated from the processing die B. The invention consists in a bending method using extracted shape memory alloy.

(Example) Hereinafter, the present invention will be specifically described using examples illustrated in the drawings.

In the embodiments shown in FIGS. 1 to 4, A is a workpiece made of aluminum such as aluminum, and B is a workpiece made of Cu-Zn-At.
This is a processing mold made of a shape memory alloy.

Processing type B is stored to have a linear shape at a temperature l1lo (normal temperature) and an arc shape at a temperature TI (approximately 70° C.). In this example, machining type B is workpiece A.
It has a pipe shape with an inner diameter slightly larger than the outer diameter of
Further, the radius of curvature at T1 is designed to be slightly smaller than the radius of curvature of the workpiece A after bending under the bending resistance of the workpiece.

Temperature T. When the workpiece A is inserted into the processing mold B in the state shown in Fig. 1) and heated to 70°C by placing it in a thermal atmosphere such as hot water or a heating furnace, or by passing an electric current, the processing mold B becomes the shape shown in Fig. 3. Therefore, the workpiece A is plastically deformed into an arc shape. At this time, since the workpiece A has elasticity, it springs back and engages elastically in the processing mold B, and cannot be easily formed into a film shape from the processing mold (FIG. 3). Next, when the mold B is taken out of the heating furnace or the electric current is turned off, the mold B gradually tries to return to the memorized linear shape at room temperature. For example, if the workpiece A is taken out from the processing mold B at a temperature T (approximately 65° C.), it can be easily removed (FIG. 4). Thereafter, the working die returns to its linear shape at room temperature and is ready for the next bending process.

In the embodiment shown in FIGS. 5 and 6, the processing die B is formed into a coil spring shape. By doing this, the coil spring can have a large difference in the amount of expansion and contraction, so the radius of curvature during bending can be made smaller than that of the main tube shown in Figure 1, and the degree of bending becomes thicker. It is possible to make a big change to object A.

FIG. 7 shows a case with a complicated cross-sectional shape.

8 and 9 show a method of processing a shape having a rectangular cross section, for example, which is bent and twisted along the longitudinal direction as in the above embodiment. This item is shown in Figures 10 to 1 described below.
A split processing die as shown in Figure 3 was used.

Figures 8 to 13 show that processing mold B is divided into two molds 1 and 2, for example, in order to facilitate demolding of workpiece A from processing mold B, and the two molds 1 and 2 are divided into delt 3 and nut 3. 4 and is removably fastened.

When using this processing die, it is also possible to separate the processing die B at a temperature of T1 and remove the workpiece A, but as mentioned above, it is better to separate the processing die at a temperature of T2 so that the workpiece A has a spring. Since there is no back, demolding is easy. Furthermore, the 8th
9 and 9 illustrate a method of processing a workpiece that is twisted along its length. In FIGS. 10 and 11, the workpiece A is a pipe, and in FIGS. 12 and 13, the workpiece A is an extruded material with a complicated cross section.

In these embodiments, the force required to deform the workpiece is adjusted by the wall thickness and cross-sectional shape of the processing mold.

(Effects of the Invention) According to the first and second inventions of the present application, pipes and extruded materials having complicated cross sections can of course be bent into arcuate shapes, and according to the embodiments, twisted shapes can also be processed. According to the invention, in addition to the above, it is also possible to perform bending in a meandering shape along the direction of the technique. Furthermore, since bending can be performed simply by applying direct heating using hot water, a thermal atmosphere such as a heating furnace, or an electric current, it has many advantages such as being able to be easily worked on site without using any fancy equipment.

[Brief explanation of the drawing]

1 to 4 are diagrams showing a first embodiment of the present invention, and FIGS. 1 and 2 show temperature T. 3 and 4 are vertical sectional views at temperatures T and T2, respectively. FIGS. 5 and 6 are side views and end views showing the second embodiment, and FIG. 7 is a vertical sectional view and an end view of the second embodiment. are end views of the third embodiment, FIGS. 8 and 9.
The figures are an end view and a perspective view of the fourth embodiment, FIG. 10, and the first embodiment.
1 is an end view and a reduced side view of the fifth embodiment, and FIGS. 12 and 13 are an end view and reduced side view of the sixth embodiment. A... Workpiece, B... Machining type, To tTI
IT2...Temperature. Patent applicant Nippon Light Metal Co., Ltd. Patent application agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Kyosuke Donakayama Patent attorney Akiyuki Yamaguchi Figure 1 Figure 3 Figure 4 Starvation procedure filed by the city (self-motivated) 1988 August Noah Day Commissioner of the Patent Office Kazuo Wakasugi1, Indication of the case Patent Application No. 99425 of 19822, Name of the invention Bending processing method using shape memory alloy 3, Person making the amendment Relationship with the case Patent Applicant name (474) Nippon Light Metal Co., Ltd. 4, agent address 5-8-10 Toranomon-chome, Minato-ku, Tokyo 105
Drawings subject to correction (Fig. 3, Fig. 12) 6. Details of correction The drawings (Fig. 3, Fig. 12) will be corrected as shown in the attached sheet. 7. Attached document catalog correction drawings (Figures 3 and 12) 1 copy (2) 3 countries page

Claims (1)

[Scope of Claims] (2) The shape of the workpiece (A) to be bent is memorized in a shape that mechanically restrains it at a predetermined temperature (To), and the workpiece (A) When the temperature k(
To) to p(T+), the above workpiece (
A processing die (B) made of a shape memory alloy memorized in a shape that mechanically restrains the workpiece (A) in a shape that takes into account the amount of springback after demolding in the shape after processing A), After restraining the workpiece (A) at the temperature (To), the workpiece (A) is changed to the temperature i ('rt) of the processing die (B).
) is subjected to bending processing, and then the temperature of the processing mold (B) (To
) and (T1), the processing mold (
A bending method using a shape memory alloy obtained by taking a workpiece (A) from B). 2. The method according to claim 1, wherein the temperature (To) is room temperature and the temperature ('r+) is higher than room temperature. 3. The method according to claim 1, wherein the temperature (To) is room temperature and the temperature ('r,) is lower than room temperature. 4. The method according to claim 1, wherein the temperature (To) is higher than room temperature and the temperature (T1) is lower than the temperature ('ro). 5. The method according to claim 1, wherein the processing mold (B) is made of a CIl-Zn-At alloy. 6. The song is memorized in a shape that mechanically restrains the shape of the workpiece (A) before processing at a predetermined temperature ('ro), and the state in which the workpiece (A) is restrained. When the temperature is changed from ('ro) to (T1) at ) The workpiece (A
) e restraint, then change the temperature of the working mold (B) to (T1) and bend the workpiece (A, ), then the working mold (B) is divided into multiple parts. A bending method using a shape memory alloy obtained by removing a workpiece (A)'e from a processing die. 7. Temperature (To) is room temperature and temperature (T,) is room temperature υ
7. The method of claim 6, wherein the temperature is also high. 8. The method according to claim 6, wherein the temperature (To) is room temperature and the temperature (T, ) is lower than room temperature. 9. Temperature ('ro) is higher than room temperature, temperature (T, )
is lower than the temperature ('ro)
The method described in section. 10. The method according to claim 6, wherein the processing mold (B) is made of a Cu-Zn-At alloy.