JPS5834215A - Clamping member - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fastening member constructed using a shape memory alloy.

Shape memory alloys exhibit the following unique properties due to phase transformation.

1) As shown in Figure 1, the apparent yield point a occurs above the transformation temperature (the temperature at which the reverse transformation from the martensitic phase to the parent phase ends).
Even if the material is deformed beyond this point (plastic deformation), if the stress is removed, the strain will be resolved and it will return to its original shape. ...Superelastic effect 2) As shown in Fig. 2, if the material is plastically deformed below the transformation temperature, a permanent strain R remains, but if it is heated above the transformation temperature, the strain is eliminated and it returns to its original shape. ... Shape memory effect and conventionally, the tightening of parts using the shape recovery of shape memory alloys and the accompanying reverse transformation stress has been proposed. FIG. 3 is an explanatory diagram of a conventional example of a stainless steel pipe joint using a shape memory alloy (hereinafter referred to as SME alloy). SME
The inner diameter of the joint made of an alloy material is formed to be about a inch smaller than the outer diameter of the pipe. When this is cooled to below the MJ point, the martensite phase is very soft and can be easily expanded. Figure (a) shows the joint in an expanded state, and the pipe is inserted in this state. When the SME alloy is then heated to the operating temperature, the inner diameter of the joint returns to its original value because the SME alloy undergoes reverse transformation. Figure (b) shows a state in which the joint returns to its original shape and tightens the pipe joint. A strong reverse transformation stress acts on the joint to prevent leakage of gas, oil, etc. passing through the pipe.

FIG. 7 is an explanatory diagram of a conventional example in which a single plate is fastened with a pin using an SME alloy. For tightening pins made of SME alloy, the pin 3 is subjected to shape memory treatment in the shape shown in the figure (,), and once it is cooled to below the M5 point, the martensite phase is very soft and can be easily bent. To tighten pin 3 after straightening the bend as shown in the same figure (b), tighten the pin 3 as shown in the same figure (C).
Insert into the insertion slots j of the two plates as shown in the figure. After this, if the temperature of the pin 3 is heated to the operating temperature, the pin 3 will return to its original shape due to reverse transformation. Therefore, the same figure (d)
The plates are joined together as shown below.

When tightening using the above-mentioned SME alloy, the parts do not require high-temperature heating unlike silver brazing, and there is no deterioration or damage due to thermal changes, and they can be removed only by rubbing them with low-temperature G. Also, places that cannot be directly accessed (nuclear related equipment, etc.)
The present invention relates to the improvement of parts using the SME alloy described above, and is particularly applicable to the technology of removal. The purpose of this invention is to provide a fastening member that has been improved and is easier to handle.

Hereinafter, embodiments of the tightening member according to the present invention will be described in detail with reference to the drawings.

1st Embodiment Referring to the conventional example shown in Fig. 3, once the pipe joint is tightened at the joint, in order to remove the joint again, the joint must be cooled to below the Mf point and brought into a martensitic state. You must expand the joint before removing it. In the first embodiment of the present invention, the joint can be removed by further heating the joint from the attached state.

FIG. 5 is an explanatory diagram for explaining the first embodiment of the present invention. Coupling / is a piece of SME alloy strip /a, /
Consists of b. The single SME alloy cylinders /a and /b are made of SME alloys having different transformation temperatures and thicknesses, and are joined to each other. Transformation temperature of SME alloy cylinder/a is TIs
The thickness is ml, and the transformation temperature of the SME alloy tube/b is T2. If the thickness is m2, then Tl(T2, ml<mz).

In addition, the inner diameter of the inner SME alloy tube/a is smaller than the outer diameter of the pipe and is subjected to shape memory treatment, and the outer SME alloy tube/a is
b is subjected to shape memory treatment so that its inner diameter is sufficiently larger than the outer diameter of the pipe.

The figure (a) shows the configuration when the external temperature T is T<T1<T2. Since both of the two SME alloy cylinders are in a martensitic state, the joint is very soft and can be expanded. In the same figure (b), the external temperature T is T+<T
The form at time 2 is shown. The SME alloy cylinder/a becomes a matrix and returns to its original shape. At this time, since the SME alloy tube /b is in a soft state of the hamata martensite phase, the joint /pipe is tightened by the contraction force of the SME alloy tube /a. The figure (c) shows the configuration when the external temperature T is TI<T2<T. SME
Alloy strips /a and /b both become a matrix and try to return to their original shape. However, as mentioned above, the inner SME alloy tube/a is treated with shape memory so that its inner diameter is smaller than the outer diameter of the pipe, and the outer SME alloy tube/b has an inner diameter that is sufficiently larger than the outer diameter of the pipe. Since the sME alloy cylinders /a and /b are subjected to shape memory treatment, the return forces of the sME alloy cylinders /a and /b act in opposite directions. As mentioned above, the thickness ml of the SME alloy tube/a is smaller than the thickness m2 of the SME alloy tube/b, so the return force is greater in the SME alloy tube/b. Therefore, the joint deforms in the direction of return of the SME alloy cylinder /b, that is, in the direction of expansion. Therefore, the pipe can be removed.

The above joint is effective in the following respects. That is, in the conventional joint shown in FIG. 3, when it is removed, it is necessary to cool the joint to turn it into a martensitic phase and expand it.

However, it is relatively time-consuming to widen a joint that has been tightened at one end. In the method of the first embodiment of the present invention, the joint itself expands, so no special work is required.

As shown in Fig. 7, referring to an example, after joining the plates with pin 3, tightening is performed again.To remove pin 3, cooling to below 5 points is required, and tightening brings pin 3 into a martensite state. When tightening, it is necessary to bend and straighten the leg of pin 3 into a straight line before removing it. In the first embodiment of the present invention, the tightening can be easily removed by further heating the pin 3.

The third figure is an explanatory diagram for explaining a second embodiment of the present invention. For tightening, each leg of pin 3 is made of one SME alloy plate! Consisting of a, lb. That one SME
The alloy plates Ja and Jb are made of SME alloys having different transformation temperatures and thicknesses, respectively, and are joined to each other. The transformation temperature of the SME alloy plate 3a is set to T1. If the thickness is "ls", the transformation temperature of the 5M8 alloy plate 3b is T2, and the thickness is n2, then T1<
Tz nnt<n2. The SME alloy plate 3a is subjected to shape memory treatment in a bent state, and the 5M8 alloy plate 3b is in a straight state (
This shape memory processing is performed.

When the external temperature T is T < Ts < T2, the two SME alloy plates J a and J b are both in the martensitic phase and are very soft, so they are made straight as shown in Figure Z (a). be able to. Tightening in this way is done by pin 3.
Insert it into the insertion slot 5 of one plate as shown in the same figure). The figure (c) shows the configuration when the external temperature is Tl<T<T2. The SME alloy plate 3a returns to its original shape as a matrix, and 5
Since the M8 alloy plate 3b is still in a soft martensitic state, the pin 3 tightens the two plates by the restoring force of the SME alloy plate 3a. The figure (d) shows the external temperature T.
indicates the form when T 3 < T 2 (T.SME
Both alloy plates 3a and Jb become the matrix and return to their original shape. However, as mentioned above, since the SME alloy plate 3a is subjected to a curved shape memory treatment and the 5M8 alloy plate 3b is subjected to a straight shape memory treatment, the return forces of the SME alloy plates 3a and Jb are in opposite directions. work. As mentioned above, since the thickness nl of the SME alloy plate 3a is smaller than the thickness n2 of the 5M8 alloy plate 3b, the return force of the 5M8 alloy plate 3b is greater. Therefore, when tightened, the pin 3 is deformed in the direction of return of the 5M8 alloy plate 3b, that is, in a straight line.

After tightening, pin 3 can be easily removed.

When tightening on a rod, a pin is effective in the following respects. In other words, even if the foot of the pin is hidden inside the device and is difficult to remove due to bending, it can be easily removed without disassembling the device by heating the head of the pin and making the foot a straight line through heat conduction. The pin can be removed.

The above embodiments are a type of SME with different transformation temperatures and cross-sectional areas.
It was constructed by bonding alloy materials together, but even if the cross-sectional area is the same, the transformation temperature and T (σ: stress T: temperature) are different.
By laminating various SME alloy materials together, it is possible to obtain a joint or a fastening pin that performs the same operation as described above.

Here, d6/dT represents the slope of transformation stress with respect to external temperature. Figure 2 shows a type of SM with different 4□
It is a graph diagram showing the relationship between transformation stress and external temperature of E alloy materials a and b. External temperature T is T < T 1 < T
In case 2, both SME alloy materials a and b are in a martensitic state. When the external temperature T is T,<T<T2, the SME alloy material a is in a matrix state, and the SME alloy material is in a martensitic phase state, and the entire material deforms as the SME alloy material a moves due to reverse transformation.

When the external temperature T is T 1 (T 2 < T), the SME alloy material a.

Both b are in the matrix state. When the external temperature T becomes T3<T, the transformation stress of the SME alloy material A is much larger than the transformation stress of the SME alloy material a, so that the whole deforms as the SME alloy material moves due to reverse transformation. The above-described deformation operation is the same as in the first embodiment and the second embodiment, and
Structurally, the first step is to simply replace the alloy material. The same operation as in the first embodiment is performed. Here, /dT can be adjusted by changing the composition of the alloy and the heat treatment conditions.

In the above examples, the SME alloy is Ti(jθ%
)-NiCjOchi), Cu-Zn-Aj! An alloy or the like may be used.

As explained above, the fastening method of the present invention is extremely convenient in that once a member is attached, it can be easily removed by further heating the member.

[Brief explanation of the drawing]

Figure 1 is a characteristic graph showing the superelastic effect, Figure 1 is a characteristic graph showing the shape memory effect, Figure 3 is an explanatory diagram of a conventional stainless steel pipe joint, and Figure 3 is a characteristic graph showing the conventional tightening. is an explanatory diagram of a pin, FIG. 5 is an explanatory diagram of a stainless steel pipe joint according to an embodiment of the present invention, and FIG. The figure is an explanatory diagram showing the relationship between transformation stress and temperature of 41 different types of SME alloy materials. In the figure, /: fitting, , 2 stainless steel pipe, 3: pin for tightening, gu: plate, j: insertion port. Agent Patent Attorney Ai Hikoka Fukushi Figure 1 Employment #I2 Figure (σ) Figure 3 (G) (b) (C) (d) Figure 4 (CI) (b) Figure 5

Claims (1)

[Scope of Claims] 1. At least a part of the device is equipped with a member formed by joining a plurality of shape memory alloy materials having the same magnitude relationship of transformation temperature and the same magnitude relationship of transformation force in a predetermined temperature state. Tighten the parts. 2. The tightening member according to item 1, characterized by comprising a plurality of shape memory alloy materials having different cross-sectional areas. 3. The tightening member according to item 1, characterized by comprising a plurality of shape memory alloy materials having different slopes of transformation stress with respect to temperature.