JP2012107262A - Method of producing member composed of shape memory alloy and actuator utilizing member composed of shape memory alloy - Google Patents

Abstract

A method of manufacturing a member made of a shape memory alloy capable of obtaining good bidirectionality is provided.
The manufacturing method includes a memory processing step S14 for performing shape memory processing on the shape memory alloy, and cooling for cooling the shape memory alloy subjected to the shape memory processing in the memory processing step to a temperature equal to or lower than the temperature of the transformation point Mf. Step S16 and a shot peening step S18 for performing shot peening on the shape memory alloy cooled to a temperature equal to or lower than the temperature of the transformation point Mf in the cooling step. In the shot peening process, the shape memory alloy is maintained at a temperature equal to or lower than the temperature of the transformation point As.
[Selection] Figure 1

Description

  The present invention relates to a method of manufacturing a shape memory alloy member having bidirectionality, and an actuator using such a shape memory alloy member. Here, “a member made of shape memory alloy” means a machine part made of a shape memory alloy.

  Shape memory alloys have the property that their shape changes with temperature. Shape memory alloys having such characteristics include a unidirectional shape memory alloy whose shape changes only in one direction due to a temperature change, and a bi-directional shape memory alloy whose shape changes in two directions due to a temperature change. In order to move the unidirectional shape memory alloy in two directions, an elastic component (such as a spring) that urges the unidirectional shape memory alloy in a direction opposite to its shape change direction is required. On the other hand, since the bi-directional shape memory alloy does not require such elastic parts, it has an advantage that the structure can be simplified and the manufacturing cost can be reduced.

  Patent Document 1 discloses a method of manufacturing a shape memory alloy member having bidirectionality. In this manufacturing method, first, a normal shape memory treatment is performed on the shape memory alloy. Next, the shape memory alloy subjected to the shape memory treatment is fixed to a predetermined shape at a temperature of the transformation point Ms + 20 ° C. or less, and shot peened. Thus, a shape memory alloy member having bidirectionality can be obtained.

JP-A-8-109455

  However, although the shape memory alloy manufactured by the manufacturing method of Patent Document 1 can obtain a certain degree of bi-directionality, there are cases where good bi-directionality cannot be obtained. In particular, when the temperature changes from low temperature (for example, −35 to 0 ° C.) to room temperature (for example, 20 ° C.), it is deformed to the second shape, and is cooled again from room temperature to return to low temperature (for example, −35 to 0 ° C.). When trying to produce a shape memory alloy that deforms to the first shape when it is, good bi-directionality was not obtained.

  This invention is made | formed in view of an above-described situation, and provides the manufacturing method of the member made from a shape memory alloy which can obtain favorable bidirectionality.

  The inventors of the present invention have made various studies on the reason why good bidirectionality cannot be obtained. As a result, it has been found that the temperature of the shape memory alloy during the shot peening treatment has a great influence. That is, according to experiments conducted by the present inventors, it has been found that when shot peening is performed in a state where the shape memory alloy is martensitic, good bidirectionality can be imparted to the shape memory alloy. The present invention was created based on the findings.

The method of manufacturing a shape memory alloy member of the present invention includes a memory processing step for performing shape memory processing on a shape memory alloy, and a shape memory alloy subjected to shape memory processing in the memory processing step at a temperature equal to or lower than the temperature of the transformation point Mf A cooling step of cooling, and a shot peening step of performing shot peening on the shape memory alloy cooled to a temperature equal to or lower than the temperature of the transformation point Mf in the cooling step. In the shot peening process, the shape memory alloy is maintained at a temperature equal to or lower than the temperature of the transformation point As.
In this manufacturing method, before the shot peening is performed, the shape memory alloy is cooled to a temperature equal to or lower than the temperature of the transformation point Mf, and substantially the entire crystal grains of the shape memory alloy are martensiticized. Then, shot peening is performed on the shape memory alloy in a state where the entire crystal grains are martensitic. During shot peening, the temperature of the shape memory alloy is maintained at a temperature equal to or lower than the temperature of the transformation point As. That is, during shot peening, the shape memory alloy crystal grains are prevented from becoming austenitic. In this manufacturing method, since shot peening is performed in a state where the entire crystal grains of the shape memory alloy are martensite, good bi-directionality can be imparted. That is, in the technique of Patent Document 1, since shot peening is performed at a temperature equal to or lower than the transformation point Ms + 20 ° C., the case of shot peening is included in the shape memory alloy in the austenitic state. For this reason, the technique of Patent Document 1 may not be able to impart good bidirectionality. On the other hand, in the manufacturing method according to the present invention, since shot peening is performed on a shape memory alloy that is substantially entirely in a martensite state, good bi-directionality can be imparted.

The method for manufacturing a shape memory alloy member may further include a casting step of casting the shape memory alloy into a predetermined shape before the memory processing step. In the memory processing step, it is preferable to perform shape memory processing on the shape memory alloy cast into a predetermined shape by the casting step.
In this manufacturing method, since the shape memory alloy is formed into a predetermined shape by casting, it is possible to suitably manufacture a shape memory alloy member having a plate shape or a complicated shape. Moreover, even if it shape | molds to predetermined shape by casting, since fatigue resistance improves by shot peening, it can be equipped with sufficient mechanical strength.

  Here, it is preferable that the cooling step cools to a temperature lower than the temperature at which the shape memory alloy is completely martensitic. “Complete martensite” means that not only the crystal grains but also the grain boundary existing at the boundary between the crystal grains becomes martensite. According to such a configuration, since shot peening is performed in a state where the martensite is formed up to the grain boundary, better bi-directionality can be imparted.

  In addition, the manufacturing method of the shape memory alloy member mentioned above can be used suitably for the shape memory alloy whose temperature of the transformation point As is 0 degreeC or less. According to the present invention, even when the temperature of the transformation point As is 0 ° C. or less, good bidirectionality can be imparted.

The present invention also provides a novel actuator using a shape memory alloy. That is, the actuator of the present invention is an actuator that drives the driven part, and includes a shape memory alloy member connected to the driven part. The shape memory alloy member becomes a first shape when its temperature falls below the first temperature, and becomes a second shape when its temperature exceeds a second temperature higher than the first temperature. The surface compressive residual stress is applied to at least a part of the surface of the shape memory alloy member.
In this actuator, the driven part is connected to a member made of a shape memory alloy having bidirectionality. For this reason, when the shape memory alloy member moves in two directions, the driven part is driven in two directions according to the movement. By using a shape memory alloy member having bi-directionality, the actuator can have a simple configuration. Further, since the surface compressive residual stress is applied to at least a part of the surface of the shape memory alloy member, it has sufficient mechanical strength.

As an example of the actuator, the shape memory alloy member may be a plate member having one end as a fixed end and the other end used as a free end. Then, more surface compressive residual stress is applied to one of the two surfaces of the plate member than to the other surface.
By applying more surface residual stress to one surface of the plate member, the plate member can be changed into a linear shape and a bent shape.
In addition, the surface compressive residual stress may be provided to the whole one surface of the plate member, or the surface compressive residual stress may be provided to a part thereof. Further, uniform surface compressive residual stress may be applied to the entire surface, and more surface compressive residual stress may be applied to a part of the surface. Bidirectionality can be imparted more satisfactorily by applying a large amount of surface compressive residual stress to the portion to be the bent portion.
Further, the surface compression residual stress may not be applied to the other surface of the plate member, or the surface compression residual stress may be applied. By applying surface compressive residual stress to the other surface, the fatigue strength of the plate member can be increased.

  In the actuator described above, the shape memory alloy member can be manufactured by any of the manufacturing methods described above. This provides an actuator with good bi-directionality.

The flowchart which shows the procedure of the manufacturing method of the actuator which concerns on one Example of this invention. The figure for demonstrating each transformation point. The figure for demonstrating the apparatus which performs a shot peening process. The perspective view of the actuator which concerns on one Example of this invention (at the time of room temperature). The perspective view of the actuator which concerns on one Example of this invention (at the time of cooling). The figure for demonstrating the effect | action of the actuator of a present Example. The figure for demonstrating the effect | action of the other actuator different from a present Example. The figure for demonstrating the effect | action of the other actuator different from a present Example. The figure for demonstrating the effect | action of the other actuator different from a present Example. A photograph of the shape memory alloy member of the experimental example (during cooling). A photograph of a shape memory alloy member in an experimental example (during heating).

The main features of the embodiments described in detail below are listed first.
(Feature 1) A shape memory alloy manufactured from a metal material powder by a combustion synthesis method is formed into a plate material by casting.
(Characteristic 2) Casting is performed by a precision casting method (lost wax method).
(Characteristic 3) A NiTi shape memory alloy of Ni 55 at% and the remaining Ti is used.
(Feature 4) Shot peening is performed on both sides of a plate material (shape memory alloy). More shot peening is performed on one surface of the plate (shape memory alloy) than on the other surface.

First Example A manufacturing method according to an example of the present invention will be described. First, an actuator made of a shape memory alloy manufactured by the manufacturing method of the present embodiment will be described with reference to the drawings. 4 and 5 show an actuator according to the present embodiment. As shown in FIGS. 4 and 5, the actuator is a plate 30. The plate 30 is formed of a NiTi shape memory alloy of Ni 54 to 56 at% and the remaining Ti. Since Ni is contained at 54 to 56 at%, the temperature of the transformation point Mf of this shape memory alloy is about −60 ° C. (Each transformation point will be described in detail later.) This NiTi-based shape memory alloy has other elements (for example, Cr, Fe, Co, V, Mn, Mo, B, Cu, Nb etc.) can be added.
One end 42 (hereinafter, referred to as a plane mounting portion 42) of the plate member 30 is fixed to a housing or the like by bolts 40 and 44. A driven member (not shown) is connected to the other end 34 (hereinafter referred to as a free end) of the plate member 30. For this reason, when the shape of the plate 30 changes according to the temperature change, the other end 34 of the plate 30 changes between the form shown in FIG. 4 and the form shown in FIG. Rocks (driven up and down).

  The plate 30 is stored in a curved shape (the shape shown in FIG. 4) by shape memory heat treatment to be described later. Further, a surface compressive residual stress is applied to the surface of the plate member 30 (the surface of FIGS. 4 and 5) by a shot peening process described later. The region to which the surface compressive residual stress is applied is a region (region on the free end 34 side) excluding the fixed end 42 (region on the fixed end side from the boundary indicated by a one-dot chain line in the drawing).

As described above, the plate member 30 is subjected to shape memory processing in a curved shape (the shape shown in FIG. 4), and surface compression residual stress is applied to the surface of the plate member 30 by shot peening. For this reason, if the board | plate material 30 is cooled and temperature becomes below predetermined temperature (for example, -30 degreeC), the board | plate material 30 will become a shape shown in FIG. Further, when the plate member 30 is heated and the temperature becomes equal to or higher than a predetermined temperature (for example, 0 ° C.), the plate member 30 has a shape shown in FIG.
That is, as shown in FIG. 6, when the shot peening process is performed on the back surface of the plate material 30 (the front surface in FIGS. 4 and 5), a work-cured region (hereinafter referred to as a shot peening portion) is formed on the back surface of the plate material 30. The When the shot peening part is formed, the shot peening part hardly changes in shape due to a temperature change. For this reason, if the board | plate material 30 is cooled and the area | regions other than the shot peening part of the board | plate material 30 turn into a martensite, the area | region which turned into the martensite will shrink, but the shape change of a shot peening part will be suppressed. For this reason, the board | plate material 30 changes to the form shown in FIG. On the other hand, when the board | plate material 30 is heated and the area | regions other than the shot peening part of the board | plate material 30 are austenitized, the area | region austenitized will expand | extend. For this reason, the board | plate material 30 changes to the form shown in FIG.

  Next, a manufacturing method for manufacturing the above-described actuator will be described. FIG. 1 shows a flowchart of the manufacturing method of this embodiment. As shown in FIG. 1, the actuator of this embodiment is subjected to a combustion synthesis step (S10), a precision casting step (S12), a shape memory step (S14), a cooling step (S16), and a shot peening step (S18). Manufactured by. Hereinafter, each process will be described.

[Combustion Synthesis Process] In the combustion synthesis process, first, the metal powder raw materials are precisely mixed so as to achieve the target composition ratio. The blending ratio is set to Ni 54 to 56 at% and the remaining Ni, and is set to a predetermined transformation temperature. Next, the raw material mixed powder is synthesized into a compound by a combustion synthesis method using a combustion synthesis reactor. That is, one end of the raw material mixed powder is ignited by ignition means such as electric discharge or heating wire heating in the combustion synthesis reaction apparatus. The ignited ignition point reaches the ignition temperature, and a chemical reaction starts. Since generation heat is generated by the chemical reaction, the heating layer is formed by being heated by the generation heat adjacent to the synthesis layer in which the chemical reaction is performed. This generated heat propagates to the surroundings to cause a chain reaction, and a heating layer and a synthetic layer are continuously formed, and finally the whole becomes a compound (alloy). At this time, the raw material is not melted macroscopically, and is produced in a state where an intermetallic compound with very few impurities is sintered. The detailed procedure of the combustion synthesis method is disclosed in, for example, Japanese Patent No. 1816876.

[Precision casting process] The plate 30 is cast by the lost wax method. Specifically, first, a mold having an internal space to be a bent shape (the shape shown in FIG. 4) is prepared. Next, the alloy obtained by the combustion synthesis method is melted, and the melted alloy is poured into a mold. Thereafter, the alloy in the mold is cooled and solidified, and then removed from the mold. During this time, no special heat treatment is required.
In addition to the lost wax method, other methods such as sand mold casting, shell molding, and centrifugal casting can be used as the casting method. Of these, the product can be selected as appropriate in consideration of the product shape and mass productivity.

[Memory Processing Step] The member taken out from the mold is subjected to a storage process within a range of 300 to 600 ° C. for several minutes to several hours, thereby imparting shape memory characteristics to the member. As described above, the plate member 30 is cast in a bent shape (the shape shown in FIG. 4). For this reason, in the memory processing step, the shape memory heat treatment can be performed in a free state without requiring a constraining mold. In addition, when performing shape memory processing by deforming / changing the shape taken out from the mold, it is natural that heat treatment can be performed using a constraining mold.

[Cooling Step] The memorized plate material 30 is cooled to a temperature equal to or lower than the temperature of the transformation point Mf. Here, the transformation points Ms, Mf, As, and Af of the shape memory alloy will be described.
FIG. 2 shows the relationship between the transformation points of the shape memory alloy. As shown in FIG. 2, when the austenitized shape memory alloy is cooled and its temperature reaches the transformation point Ms, the shape memory alloy begins to martensite. (As shown in FIG. 2, martensite formation starts at a temperature higher than the transformation point Ms. That is, the transformation point Ms is a temperature at which martensite formation starts.) Further, the shape memory alloy is cooled and its temperature is increased. Becomes the transformation point Mf, the crystal grains of the shape memory alloy are almost completely martensite. (As shown in FIG. 2, the temperature at which martensite formation is completely completed is lower than the transformation point Mf. The transformation point Mf is a temperature at which martensite formation is completed.) Therefore, the transformation point Ms. Is the temperature at which martensite formation begins, and the transformation point Mf is the temperature at which martensite formation ends. Even when the temperature of the shape memory alloy is lowered to the transformation point Mf, the grain boundary existing between the crystal grains is not martensitic. For this reason, the temperature for complete martensite is lower than the transformation point Mf.
On the other hand, when the shape memory alloy that has been martensitic is heated and the temperature reaches the transformation point As, the austenite of the shape memory alloy starts. (As shown in FIG. 2, austenitization starts at a temperature lower than the transformation point As. In other words, the transformation point As is a temperature at which austenitization starts.) Further, the shape memory alloy is heated and the temperature is transformed. At point Af, the shape memory alloy crystal grains are almost completely austenitic. (As shown in FIG. 2, the temperature at which austenitization is completely completed is higher than the transformation point Af. The transformation point Af is a temperature at which austenitization is terminated.) Therefore, the transformation point As is austenite. The transformation point Af is the temperature at which austenitization ends.
As is clear from the above description, in the cooling step, the plate material 30 is cooled to a temperature not higher than the transformation point Mf. For this reason, the crystal grains of the plate material 30 are almost completely martensite. In addition, as temperature which cools the board | plate material 30, it is preferable to set it as the temperature (for example, Mf- (50-100) degreeC) by which the board | plate material 30 becomes complete martensite. By making the plate material 30 completely martensite, the grain boundary of the plate material 30 can be made martensite.

[Shot Peening Step] Shot peening is performed on one surface of the cooled plate member 30 (that is, the back surface of FIGS. 4 and 5). An area where shot peening is performed is an area excluding the fixed end 42 of the plate member 30. During shot peening, the temperature of the plate 30 is maintained at a temperature equal to or lower than the transformation point As. For this reason, it is prevented that the crystal grain of the board | plate material 30 turns into austenite during shot peening. The method and conditions for shot peening can be changed as appropriate according to the specifications required for the plate 30.

Here, an example of a workpiece cooling device for performing the above-described shot peening process will be described. As shown in FIG. 3, the workpiece cooling apparatus 10 includes a casing 12 that is open at both ends. A cap 20 is attached to one end (upper end in the figure) of the casing 12. One end of the casing 12 is closed by the cap 20. In addition, a work mounting base 16 is attached to the other end (lower end in the figure) of the casing 12 via a holder 14. A work W (that is, a plate material 30) is attached to the lower surface of the work mounting base 16. A heat sink 18 is attached to the upper surface of the work mount 16. The heat sink 18 is located in the casing 12. A coolant 22 (for example, liquid nitrogen) is enclosed in the casing 12.
A known shot device is disposed below the workpiece cooling device 10. The shot material projected from the shot device collides with the workpiece W, and the workpiece W is subjected to shot peening processing. When the shot peening process is performed, the temperature of the workpiece W increases. At this time, the heat generated in the workpiece W flows to the coolant 22 via the workpiece mounting base 16 and the heat sink 18. As a result, the workpiece W is cooled, and the temperature of the workpiece W can be controlled to a desired temperature. Note that a Peltier element may be disposed in place of the heat sink 18, and the workpiece W may be cooled by the Peltier element.

The actuator (plate material 30) manufactured as described above is shot peened in a state where the entire crystal grains of the plate material 30 are martensitic. For this reason, good bidirectionality can be stably imparted to the plate material 30. Further, since the fatigue resistance is improved by shot peening, the plate member 30 has sufficient mechanical strength.
In the present embodiment, the shape memory alloy manufactured from the metal material powder by the combustion synthesis method is melted and the plate 30 is cast. For this reason, the influence of gravity segregation is little and the board | plate material 30 which has a homogeneous characteristic can be manufactured.

  The reason why the shape memory alloy can be favorably imparted with bidirectionality by shot peening at a low temperature (martensite state) is considered to be as follows. That is, the shape memory alloy is flexible and easily deformed at low temperatures (martensite state), whereas when it changes from low temperature (martensite state) to high temperature (austenite state), the memorized shape. It has the property of returning to In order to impart bidirectionality to the shape memory alloy, it is necessary to memorize the shape on the high temperature side and the shape on the low temperature side in the shape memory alloy. Since the shape (shape) on the high temperature side is memorized by the shape memory heat treatment, it is not particularly necessary to process the shape memory alloy for the shape on the high temperature side. On the other hand, in order to obtain a shape (shape) on the low temperature side, some processing (shot peening in the above embodiment) is required, and it is necessary to create a shape (shape) on the low temperature side by this processing. is there. For this reason, it is not preferable to perform processing (for example, shot peening) in a high temperature state and to deform from the shape subjected to the shape memory heat treatment. On the other hand, on the low temperature side, it is preferable to make the temperature as low as possible and eliminate the structure (austenite) at the high temperature to perform processing (for example, shot peening) and forcibly memorize the shape (shape) on the low temperature side. Become. For this reason, it is thought that a bidirectionality can be favorably imparted to the shape memory alloy by processing the shape memory alloy at a low temperature (for example, shot peening). Note that the grain boundary between crystals does not easily change in structure, and an austenite structure may remain in the grain boundary even when the temperature falls below the temperature of the transformation point Mf. For this reason, by processing (for example, shot peening) in a state in which this portion is martensified as much as possible, the shape memory alloy can be imparted with good bidirectionality.

  In this embodiment, shot peening is performed only on one surface of the plate member 30, but shot peening may also be performed on the other surface of the plate member 30. By performing shot peening on both sides of the plate material, the fatigue strength of the plate material can be improved. When shot peening is performed on both surfaces of a plate material, bi-directionality can be imparted to the plate material by applying more shot peening (surface compressive residual stress) to one surface of the plate material than the other surface. Furthermore, a large amount of shot peening (surface compressive residual stress) may be applied in the vicinity of the bent portion of the surface of the plate material on the bent side (the surface on the side where the radius of curvature decreases). By increasing the surface compressive residual stress partially, good bidirectionality can be imparted to the plate material.

As a suitable application example of the actuator described above, a vortex generator (refer to International Publication WO2007 / 77620A1) attached to an aircraft wing, or a chevron that suppresses noise of an aircraft jet engine (for details, see Japanese Patent Application Laid-Open No. 2008-2008). No. -593737 and Japanese Patent Application Laid-Open No. 2008-519939).
When bi-directional shape memory alloys are used as actuators for these parts used in aircraft, they change to the first form in the sky (eg, temperatures below -40 ° C.) and near the ground (eg, temperature −20 ° C.). It is desired to change to the second shape at the above temperature). In addition, since it is necessary to make the product shape into a plate shape, it is desired that the product is formed by casting, but the mechanical strength is required to be high.
In the shape memory alloy manufacturing method of the present embodiment, even if it is a shape memory alloy used for the above-mentioned purposes, by controlling the temperature of the plate material at the time of shot peening, a stable and good bi-directionality can be obtained on the plate material. Can be given. Moreover, since it shape | molds in a predetermined shape with a casting method, while it can shape | mold in plate shape and complicated shape, sufficient mechanical strength can be obtained by shot peening. For these reasons, the actuator of the present embodiment can be suitably used as an actuator for driving the aircraft parts described above. Further, by using a shape memory alloy having bidirectionality, the structure of the actuator can be simplified, and the cost can be reduced.

In the above-described embodiment, when the plate 30 is cooled, the plate 30 is in a linear state (as shown in FIG. 5), and when heated, the plate 30 is bent (as shown in FIG. 4). The actuator of the present invention is not limited to such an example. For example, as shown in FIG. 7, the shape storing process is performed in a linear state, and the shot peening process is performed on one surface. This makes it possible to produce an actuator that is in a bent state when cooled and in a planar state when heated. Further, by adjusting the strength of the shot peening process, the radius of curvature can be reduced during cooling (or heating), and the radius of curvature can be increased during heating (or cooling). If comprised in this way, it can switch to the intermediate state between the state which stood up with respect to the support member, and the stand-up state and the planar state (state parallel to a support member).
Further, as shown in FIG. 8, the shape memory treatment is performed in a state where no tensile stress is applied to the bar or tube material of the shape memory alloy, and then shot peening is performed on the entire circumference in a state where the tensile stress is applied. Processing may be performed. By doing so, it can be deformed so that it expands when cooled and contracts when heated. Furthermore, as shown in FIG. 9, shape memory processing is performed in a state where no torsional stress is applied to the shape memory alloy bar, and then shot peening processing is performed on the entire circumference in a state where the torsional stress is applied. You may do it. In this way, it can be deformed so that it rotates when cooled and returns to its original state when heated.

(Experimental example) Finally, the example which manufactured the board | plate material by the manufacturing method of a present Example is demonstrated. First, the composition ratio of Ni powder and Ti powder (Ni 55 at%, Ti 45 at%) was adjusted, and a NiTi alloy was synthesized by a combustion synthesis method. The transformation points Ms, Mf, As, and Af of this NiTi alloy were about 13 ° C., −60 ° C., −52 ° C., and 39 ° C., respectively. Each transformation point can be measured by a DSC test (JIS 7101). A plate material (length 42 mm, width 34 mm, thickness 0.75 to 0.90 mm) was manufactured by precision casting using this NiTi alloy.

  Next, shape memory heat treatment was applied to the manufactured plate material. Specific heat treatment conditions were as follows: holding at 450 ° C. for 30 minutes and water cooling. The shape memory treatment was performed with the plate material held in a bent state. Next, the plate material was cooled to −170 ° C. or lower, and shot peening treatment was performed on one surface of the plate material. A 0.8 mm steel ball (Hv800) was used for shot peening. Ultrasonic shot peening was used as the projection method, and the projection conditions were such that the ultrasonic amplitude was 70 μm. Moreover, the coverage was 4000% and the processing time was 30 seconds × 8 times.

  When the plate material produced in this way was cooled to −30 ° C. or less by cold spray (LPG gas or LPG), the bending angle of the plate material was reduced as shown in FIG. Further, when the plate material was heated to 40 ° C. or higher with a heat gun, the bending angle of the plate material increased as shown in FIG. As shown in the photographs of FIGS. 10 and 11, it was confirmed that good bidirectionality could be imparted to the plate material.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

10: Work cooling device 12: Casing 14: Holder 16: Work mounting base 18: Heat sink 20: Cap 22: Coolant 30: Plate material (actuator)
34: Free end 42: Fixed end

Claims (7)

A memory processing step of performing shape memory processing on the shape memory alloy;
A cooling step for cooling the shape memory alloy subjected to the shape memory treatment in the memory treatment step to a temperature equal to or lower than the temperature of the transformation point Mf;
A shot peening step of performing shot peening on the shape memory alloy cooled to a temperature equal to or lower than the temperature of the transformation point Mf in the cooling step,
In the shot peening process, the shape memory alloy is maintained at a temperature equal to or lower than the temperature of the transformation point As.   The method further includes a casting step of casting the shape memory alloy into a predetermined shape before the memory processing step, and in the memory processing step, shape memory processing is performed on the shape memory alloy cast into a predetermined shape by the casting step. The manufacturing method of the member made from shape memory alloy of Claim 1 characterized by these.   The method of manufacturing a member made of shape memory alloy according to claim 1, wherein the cooling step cools the shape memory alloy to a temperature lower than a temperature at which the shape memory alloy is completely martensitic.   The method for producing a shape memory alloy member according to any one of claims 1 to 3, wherein the temperature of the transformation point As of the shape memory alloy is 0 ° C or lower. An actuator that drives the driven part,
A shape memory alloy member is connected to the driven part and becomes a first shape when the temperature falls below the first temperature, and becomes a second shape when the temperature exceeds a second temperature higher than the first temperature. And
An actuator characterized in that a surface compressive residual stress is applied to at least a part of the surface of the shape memory alloy member.   The shape memory alloy member is a plate member whose one end is a fixed end and the other end is used as a free end, and is on one surface of the two surfaces of the plate member more than the other surface. The actuator according to claim 5, wherein a large amount of surface compressive residual stress is applied.   The actuator according to claim 5 or 6, wherein the shape memory alloy member is manufactured by the manufacturing method according to any one of claims 1 to 4.