JPH0451209Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Field of industrial application] This invention relates to the improvement of a washer. Specifically, it acts to prevent loosening when screws are tightened together, and to tighten them when disassembling a screw connection. This relates to a washer that functions to facilitate loosening.

[Conventional technology]

Conventionally, various methods have been used to prevent screw connections from loosening, such as spring washers, rubber washers, and lock nuts, in order to increase or maintain the contact pressure of the threads, but none of them have sufficient reliability. We have not yet reached the point where we can obtain the desired results. Other active methods include locking the nut or locking the nut to the object to be tightened, but these have the disadvantage that they cannot be easily disassembled, and it is easy to both prevent and loosen the screw connection. There is no means of connection.

[Problem that the invention aims to solve] Reliable locking screw connections generally have a complicated structure and cannot be easily disassembled, so it is important for screw parts to have both reliable locking and easy loosening. It was a great challenge. This invention focuses on such problems and aims to provide a washer that has both the functions of locking and loosening screws.

[Means to solve the problem]

The purpose of this invention is to provide a first annular member made of a shape memory alloy, and a second annular member made of a shape memory alloy whose upper and lower surfaces are sandwiched via an annular electrical insulator.
It is a structure consisting of an annular member and annular electrical insulators provided on the upper and lower surfaces of the annular member, each of which is arranged concentrically. The transformation start temperature exceeds the operating atmosphere temperature, and at or above the reverse transformation start temperature, the first annular member undergoes a predetermined vertical expansion deformation, and the second annular member undergoes a predetermined vertical contraction deformation. This is achieved by providing a washer with a pre-memorized aspect.

[Effect]

A fastener such as a bolt is screwed together until it comes into contact with a washer, and then the first annular member of the washer, which is in a vertically contracted state, is heated to a temperature above the reverse transformation start temperature to cause it to expand in the vertical direction. cause it to occur. As a result, the entire washer generates a pressing force in the vertical direction, applying sufficient contact pressure to the screw thread and fixing the tightened position. In particular, as is well known, the stress generated during reverse transformation of shape memory alloys can reach large values, so that it is also possible to maintain a fixed tightening position and prevent the screw from loosening.

On the other hand, when the screw connection is disassembled, the second annular member is heated to a temperature higher than the reverse transformation start temperature, causing the second annular member to contract in the vertical direction. As a result, the entire washer contracts in the vertical direction and the pressing force disappears, so that the pressing force on the screw thread disappears, the fixation and maintenance of the tightened position of the screw is released, and the screw is loosened and fastened. Work can be done easily and quickly.

As is clear from the above, since there is no pressure applied to the screw threads at that stage, the fasteners can be screwed together and removed with bare hands. This is due to the advanced technology that is only possible through the implementation of this invention.

〔Example〕

Hereinafter, specific embodiments of this invention will be explained based on the accompanying drawings.

In this embodiment, a first annular member 1 is formed with a circular cross section, a second annular member 2 is formed with a U-shaped cross section, and a sheet-shaped electrical insulator 3 is attached to the outer surface of the member 2. ing. Further, electrical insulators 4 and 5 in the form of annular flat plates are attached to the upper and lower surfaces of the member 2, respectively. The operating atmosphere temperature is room temperature, and the material of parts 1 and 2 is a TiNi alloy with a reverse transformation starting temperature of 55°C and a martensitic phase change starting temperature of 50°C.
It is set at ℃.

At room temperature, a fastener 6 such as a bolt is screwed into an object 7 until it comes into contact with a washer, and then the first annular member 1 of the washer, which is in a vertically contracted state, is heated to 55°C or higher to cause it to expand vertically. As a result, the washer applies a pressing force to the fastener 6 and the object 7, thereby applying sufficient contact pressure to the threads, fixing the fastening position and maintaining that state.

On the other hand, when disassembling a threaded joint at room temperature, the second
The temperature of the annular member 2 is raised to 55° C. or higher to cause it to contract in the vertical direction. At this time, the annular member 1 at a temperature lower than 50° C. is in the martensitic phase, and its stress is smaller than the stress of the annular member 2 in the high temperature phase, so the contraction force of the annular member 2 is 1, the annular member 2
With the contraction behavior of the annular member 1, the annular member 1 also contracts, and as a result, the entire washer contracts in the vertical direction, the pressing force applied to the fastener 6 and the object 7 to be fastened disappears, and the pressing action on the thread is no longer applied. The tightening and fixing of the screws and their maintenance are released, and the fasteners 6 such as bolts can be easily loosened by turning them by hand.

It is known that the strain of TiNi-based alloys is usually about 8% or less, and the amount of strain is appropriately selected and adjusted in the step of creating deformation memory as described above to reduce the strain of the washer and the compressive stress caused by it. All you have to do is select and apply it.

It is convenient to heat the members 1 and 2 described above by electric heating, and a dedicated connector (not shown) having two terminals that can be connected to member 1 when tightening and to member 2 when loosening is used. You can achieve your purpose by simply preparing the power supply and connecting it to an outlet.

The electrical insulators 3, 4, and 5 described above are provided in consideration of such electrical heating work, and silicone rubber is one of the preferred materials in terms of electrical insulation, heat resistance, flexibility, etc. has been selected as.

[Effect of idea]

As mentioned above, the invented washer has both the function of locking and loosening the screw, so it can easily perform both tightening and loosening of the screw connection, and has a high cost. Since reliability can be obtained, it greatly contributes to work improvement.

In particular, fasteners such as bolts can be screwed in and removed by hand, which is highly convenient.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing one embodiment of this invention, Fig. 2 is a cross-sectional view explaining the expansion state from top to bottom, Fig. 3 is a cross-sectional view explaining the contraction state from top to bottom, Fig. 4 is an explanatory view of the main part showing the state before and after fastening, Fig. 5 is an explanatory view of the main part showing the state during fastening. 1...First annular member, 2...Second annular member, 3, 4, 5...Electrical insulator, 6...Fastener (bolt), 7...Object to be fastened.

Claims (1)

[Scope of utility model registration request] A first annular member made of a shape memory alloy, a second annular member made of a shape memory alloy whose upper and lower surfaces are sandwiched via an annular electrical insulator, and an annular electrical insulator provided on the upper and lower surfaces of the first annular member. After the screws are screwed together and tightened, the structure expands vertically by reverse transformation heating of the first annular member to fix the tightened position, and the tightening is disassembled. A washer characterized in that the structure is vertically contracted by reverse transformation heating of the second annular member to release the fixation at the tightened position.