JPH0325497Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention uses a shape memory alloy formed into an annular shape, and connects the ends of the pipes to be connected by the diameter-reducing deformation during thermoelastic transformation. Regarding pipe fitting devices,
More specifically, the present invention relates to a pipe joint device that has a means for connecting the end portions of connected pipes to each other in a pressure-contact state in the axial direction.

[Prior Art] In general, alloys exhibiting this type of shape memory effect include, for example, Ni-Ti alloys and certain copper alloys. As a pipe joint device that utilizes this shape memory effect, a device configuration as shown in FIG. 2 has already been proposed by Raythiem, Inc. of the United States.

That is, in the configuration of the pipe fitting device shown in the conventional example in FIG. It is formed into an annular shape using a corrosion-resistant material to correspond to the diameter of the connected pipes 11 and 12, and has protrusions 1 on both the inner and outer peripheral surfaces to improve sealing performance and pull-out resistance.
3a and 13b are formed, and further, 14 is formed into an annular shape corresponding to the pipe diameter of the liner using a shape memory alloy, for example, a Ni-Ti alloy,
At the same time, it undergoes thermoelastic transformation in advance, in which the diameter is expanded in the radial direction in a martensitic state at a low temperature, and when it is used, it transitions to an austenitic state at room temperature, and the radial tightening force for a sealing joint is created by the radial diameter reduction. This is the attached driver.

In the case of a pipe joint device using a shape memory alloy according to the conventional example, the pipe fitting device is heated to about -196°C by, for example, immersing it in liquid nitrogen to prevent thermoelastic transformation. Using the shape memory alloy driver 14 kept in a cooled state, and with a liner interposed inside the driver 14, the butt ends 11 of the connected pipes 11 and 12 are removed.
Quickly insert a and 12a into each and match them,
By leaving this at room temperature, the temperature is raised,
The abutting ends 11a and 12a of these connected pipes 11 and 12 can be connected and bonded to each other by the diameter reduction deformation accompanying the thermoelastic transformation as the temperature rises.

[Problem that the invention attempts to solve]

However, the characteristics of the conventional pipe joint device using shape memory alloy are that it is clean overall, is gas leak tight, and does not require the use of fire or the like for connection. However, on the other hand, shape memory alloy drivers As the temperature rises, the diameter contracts in the radial direction and exerts the desired tightening force, but when the temperature rises, there is usually some stretching in the axial direction (usually about 0.2%), and the As a result, the abutted ends 11a, 1 of the connected pipes 11, 12 that had been abutted in advance during the joining operation
The space between 2a is separated and the space 15 is created,
Due to the existence of this gap 15, the abutting ends 11a,
12a, interstitial corrosion may occur,
Another problem is that it cannot be applied to piping systems in semiconductor device manufacturing equipment, food processing equipment, etc., where absolute cleanliness is required during use, as foreign matter tends to adhere thereto.

This invention was made in order to improve these conventional problems, and its purpose is to eliminate the risk of gaps occurring between the butt ends of the pipes to be connected during connection and coupling. It is an object of the present invention to provide a pipe joint device using this type of shape memory alloy, which is free from the problems.

[Means for solving problems]

In order to achieve the above object, the pipe joint device according to the present invention applies an action that causes the driver made of the shape memory alloy to undergo radial contraction deformation and axial contraction deformation at the same time during thermoelastic transformation. In addition to sealing the abutting ends of the pipes to be connected to each other by reducing the diameter, it is also possible to achieve a direct or indirect contact pressure connection between the abutting ends by reducing the length.

[Effect]

In other words, in this device, the driver inserted between the butt ends of the pipes to be connected is deformed by the diameter reduction and length reduction due to thermoelastic transformation from the expected low temperature state to room temperature, and the diameter reduction causes radial tightening. The abutting ends can be simultaneously sealed together by force, and the abutting ends can be directly or indirectly connected by contact pressure to each other by the axial shrinkage force caused by contraction.

〔Example〕

Hereinafter, one embodiment of the pipe joint device according to this invention will be described in detail with reference to FIG. 1.

FIG. 1 shows a schematic configuration of a pipe joint device according to this embodiment, and in this device, reference numerals 1 and 2 denote a pair of connected pipes, 1a and 2a
3 is the abutting end of the pipes 1 and 2 to be connected, and 3 is a shape memory alloy, for example, a Ni-Ti alloy, which is formed into an annular shape corresponding to the diameter of the pipes 1 and 2 to be connected, and is formed in advance. This driver is capable of causing radial diameter reduction and axial lengthening deformation through thermoelastic transformation.

That is, the driver 3 is given expansion in the radial direction and elongation in the axial direction when it is in a martensitic state at a low temperature, and then contracted in the radial direction when it transitions to an austenitic state at room temperature during use. The tightening force due to the axial contraction and the contraction force due to the axial contraction are applied. More specifically, the driver 3 is first cut into a predetermined shape using a Ni-Ti alloy, heated at 400°C for 5 hours in an argon atmosphere, and then cooled with water. Then, in liquid nitrogen, it is expanded by about 5% in the radial direction and expanded by about 3% in the axial direction.

In the figure, reference numeral 4 denotes, for example, a soft gasket packing, which is interposed between the abutting ends 1a and 1b of the connected pipes 1 and 2, if necessary.

Therefore, in the case of this embodiment configuration, the connected pipes 1,
In order to connect and connect the abutting ends 1a and 2a of the two, first, the driver 3 is held at a predetermined temperature or lower (in a martensitic state) in, for example, liquid nitrogen. Appropriately take it out with a heat-insulating gripping device or the like, and from both ends thereof, connect the abutting ends 1a, 2a of the pipes 1, 2 to be connected directly or with a gasket packing 4 interposed as necessary. , quickly insert them into each other, butt them against each other, and leave them at room temperature to raise the temperature (to an austenitic state).

In other words, with this operation, driver 3 has the following:
Thermoelastic transformation causes radial diameter contraction and axial contraction deformation, and the abutting ends 1a and 2a of these connected pipes 1 and 2 are hermetically connected to each other by the radial tightening force caused by the diameter contraction, and At the same time, they can be connected to each other by contact pressure either directly or indirectly through the gasket packing 4 by the axial shrinkage force caused by the contraction. That is, in this way, the connected piping 1,
The abutting ends 1a, 2a of the two can be sealed together in a state where they are brought into contact with each other, and with the interposition of the gasket packing 4, the abutting ends 1a,
A good sealing effect between the two parts can be obtained.

Note that the vertical cross-sectional shape of the driver 3 is as follows:
It is also effective to make the diameters of both end portions gradually smaller than that of the central portion in the axial direction, in that the aforementioned functions and effects can be made even more remarkable.

Furthermore, if a grip 5 with excellent heat insulation properties is provided on the outer peripheral surface of the axially central portion of the driver 3, as shown by the dashed line in FIG. The temperature is raised from the end, and the connected pipes 1 and 2 can be drawn together more effectively.

[Effect of idea]

As described in detail above, this invention has a driver molded using a shape memory alloy, and the diameter reduction deformation of this driver due to thermoelastic transformation at room temperature causes the pipe end of each connected pipe to In the pipe joint device that connects each other, the driver is given an action that can cause radial contraction deformation and axial contraction deformation during thermoelastic transformation, so that the butt ends of each connected pipe due to diameter contraction are In addition to the sealing connection between the pipes, it is possible to achieve a direct or indirect contact pressure connection between the ends of the same butt due to contraction, and in particular, by using the contraction force caused by the contraction, the butt of each connected piping can be achieved. Since the ends are brought into contact with each other, unlike the conventional pipe joint device using a screwdriver using this type of shape memory alloy, there is no pressure between the butt ends of each pipe to be connected. This has various practical effects, such as being able to eliminate the risk of creating a time lag, and being simple in structure and easy to implement.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the general structure of an embodiment of the pipe joint device according to the present invention, and FIG. 2 is a cross-sectional view showing the general structure of the pipe joint device according to the conventional example. 1, 2... Piping to be connected, 1a, 2a... Butt ends of the piping to be connected, 3... Driver, 4... Gasket packing.

Claims (1)

[Claims for Utility Model Registration] (1) Shape memory formed into an annular shape corresponding to the diameter of at least the end of the pipe to be connected, and deformed to reduce its diameter by thermoelastic transformation from a desired low temperature state to room temperature. In a pipe joint device that has a driver made of an alloy and connects the pipe ends of a pair of connected pipes to each other by diametrical deformation of the driver, the driver undergoes radial diametrical deformation during thermoelastic transformation. At the same time, it provides an action that can cause axial contraction deformation, and in addition to sealing the butt ends of the connected pipes together by reducing the diameter, direct or indirect contact pressure connection of the butt ends by contraction. A pipe joint device characterized in that it obtains the following. (2) The pipe joint device according to claim 1 of the utility model registration, characterized in that a gasket packing is interposed between the abutting ends of the pipes to be connected.