JP7010379B2 - Helisert - Google Patents

Description

The present invention relates to a helisert that evenly distributes the load to the fastening threads.

In a structure in which a plurality of members are combined, there is a method of fixing the members to each other by using a male screw and a female screw that are butterflies to each other. For example, if a bolt, which is a kind of male screw, is passed through one member, and the bolt is inserted into a female screw formed on the other member and tightened, the two members are fixed by the screw action. Further, the bolt is passed through the two members, the bolt is fitted to the nut using the nut, and the bolt is tightened. Similarly, the two members are fixed by the screwing action of the bolt and the nut.

In fixing such a structure, the material and dimensions of the members are determined in consideration of the load and safety factor. However, the material of the female screw member may be limited. For example, when a plastic material or a non-iron metal such as an aluminum material is fixed as a female screw, for example, when an iron-based material is used for the bolt, both members are used. If the strength of the members is too different and an impact load is frequently applied between the members, the threads of the members on the soft side may be damaged and fastening may not be possible. In such cases, helisert is often used. As the helisert, a material having high hardness such as stainless steel is used.

Normally, in nut fastening, for example, in a nut, about 3 threads on the nut fastening side (the side in contact with the object to be fastened) share the load, and the remaining threads, especially the open side (opposite the nut fastening side). The threads on the side) make little contribution to the load sharing. The same applies to the fastening by the helisert, and the load is shared by up to about 3 coils on the fastening side, and the remaining coils do not contribute much to the load sharing.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a helisert capable of making the load of each coil of the helisert more even. That is, the present invention provides a uniform load sharing type helisert that improves the conventional non-uniform load sharing.

The present invention provides the following inventions in order to solve the above problems.
(1) A helisert characterized by being formed using a Ti—Nb-based alloy.
(2) The helisert according to (1) above, wherein the Ti—Nb alloy is represented by Ti ₃ (Nb, Ta, V) + (Zr, Hf) + O.
(3) The Ti-Nb alloy is Ti-23Nb-2Zr-0.7Ta-O (mol%), Ti-12Ta-9Nb-3V-6Zr-O (mol%), or Ti-36Nb-2Ta-. The helisert according to (2) above, which is 3Zr-O (mol%).
(4) The helisert according to any one of (1) to (3) above, wherein the surface of the helisert coil to be stressed is coated with a DLC film.
(5) A helisert formed by inclining Young's modulus in the height direction perpendicular to the coil cross section of the helisert.
(6) A method for producing a helisert, which comprises performing a non-uniform heat treatment in the height direction perpendicular to the coil cross section of the helisert to obtain a helisert having a Young's modulus inclined in the height direction.

The appearance of an example of the helisert of the present invention is shown. It can have the same appearance as a conventional general helisert. The strain-strain characteristics of the helisert using the conventional stainless steel material (SUS304) and the superelastic Ti-36Nb-2Ta-3Zr-O (mol%), which is an example of the present invention, are compared and shown. The figure which shows how the helisert of this invention is set in the base metal screw hole for screw processing to a base material. In the helisert of the present invention, the figure which shows the example which changed the Young's modulus in the height direction perpendicular to the helisert cross section, that is, inclined the Young's modulus in the height direction.

The helisert of the present invention is formed by using a Ti—Nb-based alloy. This Ti—Nb-based alloy has a Young's modulus of about 45 to 90 GPa (variable depending on the aging hardening treatment conditions), which is smaller than that of the steel-based material of about 200 to 210 GPa. On the other hand, the hardness is HV≈400 during cold working and the tensile strength is about 900 to 1100 MPa, so that it is easily deformed but not easily broken. It also has the characteristic of being easy to cold work.

The helisert is usually formed by winding a wire rod having a rhombic cross section in a coil shape. The apex angle of the rhombus in the cross section is usually 60 degrees. Usually, a stainless steel material (for example, SUS304) is used.

FIG. 1 is an external view of a helisert showing an embodiment of the present invention. The appearance may be the same as the appearance of a conventional helisert. In FIG. 1, 1 is a helisert, 2 is a wire rod of a coil, 3 is a protrusion (also referred to as a tongue), and 4 is a direction perpendicular to the cross section of the coil. The coil wire of 2 is processed into a rhombus shape with an apex angle of 60 degrees. Reference numeral 3 denotes a protrusion used when mounting the helisert on the base material for fastening, and is used for rotating and mounting the helisert in the screw hole of the base material using this protrusion (cut out after the insertion set). Although an example having the protrusion 3 is shown in FIG. 1, another method useful for mounting the helisert 1 in the screw hole, for example, a groove for hooking a tool may be formed in a part of the coil.

The helisert of the present invention is a Ti-Nb-based superelastic material produced in a rhombic linear shape having an apex angle of 60 degrees, for example, Ti ₃ (Nb, Ta, V) + (Zr, Hf) + O, preferably. Ti-23Nb-2Zr-0.7Ta-O (mol%), Ti-12Ta-9Nb-3V-6Zr-O (mol%), or Ti-36Nb-2Ta-3Zr-O (mol%) in a coil It is achieved by winding it to a predetermined height. Geometric dimensions may be similar to conventional stainless steel heliserts.

FIG. 2 shows a comparison of strain-stress characteristics of a helisert using a conventional stainless steel material (SUS304) and a superelastic Ti-36Nb-2Ta-3Zr-O (mol%) which is an example of the present invention. In FIG. 2, (a) shows the strain-strain characteristics of the stainless steel material (SUS304), and (b) shows the strain-stress characteristics of the superelastic Ti-36Nb-2Ta-3Zr-O (mol%). The superelastic Ti—Nb-based material shown in (b) is characterized by having a very wide elastic deformability.

In a normal stainless steel helisert, the first coil on the fastening side (the side in contact with the object to be fastened) shares the maximum load, and in the second stage, the load sharing decreases, and up to about 3 coils share the fastening load at most. , Other coils hardly share the load at the time of fastening. When a helisert made of the Ti-Nb-based material of the present invention is used for a nut for fastening, it is easily elastically deformed when a load is applied to the coil on the fastening side, and the elastically deformed state changes according to the applied load. The load will be distributed and shared by all coils independently.

FIG. 3 is a diagram showing how the helisert of the present invention is set in a base screw hole for screwing into a base material. In FIG. 3, the //// portion indicates a portion where a bolt is inserted. As will be described later, when the Young's modulus is inclined in the height direction perpendicular to the coil cross section, the Young's modulus on the bolt insertion side (that is, downward) in the figure is lowered.

Further, when age hardening heat treatment is applied, Young's modulus increases and elastic deformability decreases. If you think about the screw thread, it will change so that it becomes harder. By changing the heat treatment conditions in the height direction, the Young's modulus of the screw thread is inclined, the Young's modulus of the helisert coil on the bolt inlet side is low Young's modulus, and the Helisert coil on the opposite side of the bolt outlet is relatively high Young's modulus. As a result, the helisert coil portion on the way becomes a screw thread in which Young's modulus is continuously inclined.

Although a high load is borne on the bolt inlet side, the thread is elastically deformed according to the load due to the low Young's modulus of the coil, the load stress is passed to the next thread, and the load stress is sequentially applied to the screw on the bolt outlet side. I will hand it over. Since Young's modulus increases as it approaches the outlet, elastic deformation decreases and a large load can be borne. In this way, it is possible to improve the state in which the fastening load is shared by about 3 threads on the fastening side in the past, so that the fastening load can be distributed and shared by many threads. Further, as a result, by load balancing, it becomes possible to receive a larger load as a whole.

FIG. 4 shows an image diagram in which Young's modulus is inclined in the height direction perpendicular to the coil cross section of the helisert, but in the helisert using a Ti—Nb-based alloy, about 45 to 90 GPa can be obtained. FIG. 4 shows an example in which Young's modulus is changed linearly in the height direction, but it can also be changed curvilinearly.

The general method of age hardening is to put the material in a vacuum heat treatment furnace, keep the whole at the same temperature for the required time, and make the Young's modulus and hardness uniform. In a preferred embodiment of the present invention, the coiled helisert is cooled in an inert gas atmosphere on one side and heated on the other side, held for a certain period of time, and heat-treated in a non-uniform height direction perpendicular to the coil surface. A helisert having a Young ratio inclined in the height direction perpendicular to the cross section of the helisert coil can be obtained.

As a non-uniform heat treatment, for example, one side in the height direction is induced and heated at about 600 to 800 ° C. for 1 to 3 minutes in an inert gas atmosphere, and the other side is exposed to running water to cool. Is done.

As a result, the fastening stress received at the bolt side screw thread and the thread valley bottom is dispersed over the entire portion where the nut stress is borne, so that the stress concentration on the screw thread / valley bottom is reduced. Since the load is distributed and received by many piles of bolts and nuts, the tolerance to external force increases and the stability of fastening increases.

In a preferred embodiment of the present invention, the coil surface of the helisert that receives the fastening load is coated with a DLC (diamond-like carbon) film. As a method for depositing a DLC film, a vapor phase deposition method is preferable, and examples thereof include plasma CVD using a direct current, alternating current, high frequency, or the like as a power source, or a sputtering method such as magnetron sputtering or ion beam sputtering. PVD (Physical Vapor Deposition) can also be used. The film thickness of these DLC films is usually selected from about 50 nm to 500 μm.

Further, in a preferred embodiment of the present invention, there is provided a helisert having a Young's modulus tilted in a height direction (direction 4 in FIG. 1) perpendicular to the cross section of the coil. Here, the slope of Young's modulus in the height direction is about 45 to 90 GPa with a helisert manufactured using a Ti—Nb-based alloy.

In one embodiment, such a helisert is obtained by subjecting a non-uniform heat treatment in the height direction perpendicular to the coil surface of the helisert.

For the non-uniform heat treatment, as described above, for example, one side of the helisert in the height direction is induced and heated at about 600 to 800 ° C. for 1 to 3 minutes in an inert gas atmosphere, and the other side is held at about 600 to 800 ° C. It is performed by exposing it to running water and cooling it.

The material of such a helisert is preferably manufactured by using the above-mentioned Ti—Nb-based alloy, but is not limited to these, and may be a steel-based material, a polymer-based material, or the like.

In the present invention, the case where the helisert using the Ti—Nb-based material is applied has been described, but the present invention is not limited to this. The heliserts of the present invention include other so-called insert nuts such as Irisert® and Enzart.

The present invention may provide a uniform load sharing type helisert that improves the conventional non-uniform load sharing.

1 Helisert 2 Coil wire 3 Protrusion 4 Direction perpendicular to the coil cross section

Claims (6)

It is a coiled helisert, which is formed by using a Ti—Nb alloy , and the coil part has a low Young's modulus on one end side in the axial direction and a high Young's modulus on the opposite end side. , A helisert characterized by continuously tilting Young's modulus of the coil part in the middle . The helisert according to claim 1, wherein the Ti—Nb-based alloy is represented by Ti ₃ (Nb, Ta, V) + (Zr, Hf) + O. The Ti-Nb-based alloy is Ti-23Nb-2Zr-0.7Ta-O (mol%), Ti-12Ta-9Nb-3V-6Zr-O (mol%), or Ti-36Nb-2Ta-3Zr-O. The helisert according to claim 2, which is (mol%). The helisert according to any one of claims 1 to 3, wherein a surface of the helisert coil that receives stress of fastening is coated with a DLC film. A coiled helisert formed of a Ti—Nb alloy is subjected to non-uniform heat treatment from one end side in the axial direction of the helisert coil portion toward the other end side, and the coil portion is subjected to non-uniform heat treatment. A method for producing a helisert, characterized in that a helisert is obtained by continuously inclining the Young's modulus of a coil portion in the middle, with one end side having a low Young's modulus and the opposite end side having a high Young's modulus. .. The Ti—Nb alloy is Ti ₃ The method for producing helisert according to claim 5, which is represented by (Nb, Ta, V) + (Zr, Hf) + O.

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