Welding nuts

Abstract

To provide a projection welding nut which enables projection welding to be performed easily to a surface of an adherend, such as a steel plate, without causing harmful effect on a screw groove on an inner peripheral surface of a bolt insertion hole and can be easily produced at low costs.SOLUTION: In a welding nut 1, a flange part 5 is integrally provided with an outer periphery of a lower edge of a cylindrical nut body 2 in which a bolt insertion hole 7 is formed. Projections 6, 6 .. are provided so as to project downward on a lower surface of the flange part 5. Further, a sleeve 3 having an inner diameter larger than an inner diameter of the bolt insertion hole 7 and made of an insulation material is provided at the interior of the lower edge of the nut body 2 so as to protrude from the lower end of the nut body 2.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a welding nut that is fixed (welded) to the surface of an adherend such as a steel plate by welding. More specifically, the present invention relates to a welding nut that is fixed to the surface of an adherend by using so-called projection welding.

Background Art

[0002] When fixing a nut to the surface of an adherend such as a steel plate, conventionally, the nut has been welded to the surface of the steel plate or the like by methods such as arc welding or gas welding. However, when welding a nut to the surface of a steel plate or the like by methods such as arc welding or gas welding, there has been a problem that spatter scatters and adheres to the thread groove on the inner peripheral surface of the nut. Therefore, as a welding method to replace arc welding, gas welding, etc., a nut provided with a protrusion on the lower end surface is used, electricity is passed through the contact portion between the protrusion of the nut and the steel plate or the like, and the protrusion on the lower end surface of the nut is melted by using the resistance heat during energization, and at the same time pressure is applied to weld the nut and the steel plate or the like (so-called projection welding) is widely adopted.

[0003] However, in the method of welding a nut to a steel plate by the above-mentioned projection welding, there has been a problem that it is difficult to accurately position the nut with respect to the bolt insertion hole of the steel plate. Therefore, as in Patent Document 1, a method of projection welding in a state where a positioning pin made of an insulating material is inserted into the screw hole of the nut and the bolt insertion hole of the steel plate, or as in Patent Document 2, a cylindrical guide is integrally formed so as to protrude downward at the lower end of the nut, and a method of projection welding in a state where the guide is inserted into the bolt insertion hole of the steel plate has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] However, in the projection welding method described in Patent Document 1, where a positioning pin made of insulating material is inserted into the bolt insertion hole of the nut and the bolt insertion hole of the steel plate, in order to accurately position the nut relative to the bolt insertion hole of the steel plate, the outer diameter of the positioning pin must be matched to the bolt insertion hole of the nut, which has the drawback of being difficult to remove after projection welding. On the other hand, in the projection welding method described in Patent Document 2, where a cylindrical guide integrally formed at the lower end of the nut is inserted into the bolt insertion hole of the steel plate, when current is passed between the nut and the steel plate, there is a risk that the current will flow not only through the projection but also through the guide, causing the guide to melt.

[0006] The object of the present invention is to solve the problems of the conventional welding nuts and welding methods using said nuts, and to provide a projection welding nut that can be easily performed on the surface of a workpiece such as a steel plate without adversely affecting the screw groove on the inner surface of the bolt insertion hole, and that can be manufactured inexpensively and easily. [Means for solving the problem]

[0007] The invention described in claim 1 of the present invention is a welding nut welded onto a metal plate by projection welding, wherein a circular flange portion is integrally provided on the outer circumference of the lower end of a cylindrical nut body having a bolt insertion hole drilled therein, a projection is provided on the lower surface of the flange portion so as to protrude downward, and a sleeve made of an insulating material having an inner diameter larger than the inner diameter of the bolt insertion hole is provided inside the lower end of the nut body so as to protrude from the lower end of the nut body, and the projection is conical, frustoconical, pyramidal or frustoconical in shape, and is provided at equal intervals along the outer circumference of the lower surface of the flange portion, and the sleeve is One of the following: polyimide, polyetheretherketone, or polyphenylene sulfide It consists of a sleeve, and at the upper edge of its outer circumference, there is a strip-shaped engaging means to prevent it from falling off the nut body, with a larger diameter than the lower part. The engagement means is formed such that the lower surface is inclined, and the difference between the inner diameter of the sleeve and the inner diameter of the bolt insertion hole in the nut body is adjusted to be less than 2.0 mm. It is characterized by the following:

[0008] The invention described in claim 2 is characterized in that, in the invention described in claim 1, the sleeve is integrally formed with the nut body by insert molding. [Effects of the Invention]

[0010] The welding nut described in claim 1 allows for precise positioning to be welded when projection welding is performed by fitting a sleeve, which is provided to protrude from the lower surface of the nut body, into a bolt insertion hole drilled in the workpiece such as a steel plate. Furthermore, the sleeve provided on the nut body effectively prevents molten projections from entering the bolt insertion hole of the nut body.

[0011] The welding nut described in claim 2 can be manufactured inexpensively and easily because the sleeve is integrally formed with the nut body by insert molding.

[0012] The welding nut described in claim 3 has an engaging portion formed at the upper edge of the outer circumference of the sleeve to prevent it from falling off the nut body, thus effectively preventing the sleeve from unintentionally detaching from the nut body. [Brief explanation of the drawing]

[0013] [Figure 1] This is a plan view of a welding nut. [Figure 2] This is a bottom view of a welding nut. [Figure 3] This is a front view of a welding nut. [Figure 4] This is a vertical cross-sectional view of a welding nut (cross-sectional view along line AA in Figure 1). [Figure 5] This is an explanatory diagram (vertical cross-sectional view) showing the usage state of a welding nut (a shows the state before welding to the steel plate, and b shows the state after welding to the steel plate). [Modes for carrying out the invention]

[0014] <Structure of welding nuts> Figures 1 to 4 show a welding nut for welding to a steel plate, which is the workpiece. The welding nut 1 is composed of a nut body 2 and a sleeve 3. The nut body 2 is integrally formed from metal (stainless steel), and a circular flange portion 5 is formed so as to protrude outward (radially from the center in the horizontal plane) from the base (lower end) of the engagement portion 4, which is formed in a roughly hexagonal prism shape. On the outer peripheral edge of the lower surface (back surface) of the flange portion 5, there are six roughly frustoconical protrusions 6, 6·· with a predetermined height (approximately 2.0 mm) at equal intervals (at equal angles from the axis center). Protruding It is being done.

[0015] Also, at the center of the substantially hexagonal columnar engaging portion 4, a bolt insertion hole 7 for screwing with a bolt (not shown) is formed, and a thread groove 8 is engraved on its inner peripheral surface. The thread groove 8 has an inner diameter of about 10 mm. Further, at the lower end of the bolt insertion hole 7 of the nut body 2, a fitting hole 9 having a larger diameter than the bolt insertion hole 7 (that is, the inner diameter is about 4.0 mm larger than the engraved portion of the thread groove 8) is formed, and at the upper end of the fitting hole 9, a fitting recess 10 is formed so as to have a larger diameter than the lower portion. And a sleeve 3 is in a state of being fitted into the fitting hole 9.

[0016] The sleeve 3 is formed of a heat-resistant synthetic resin (polyimide), which is an insulating material, into a flat cylindrical shape with a thickness of about 1.5 mm and an inner diameter of about 11 mm. And on the outer periphery at the upper end, a belt-shaped fitting projection 11 is formed so as to have a larger diameter than the lower portion. The sleeve 3 is integrally assembled to the nut body 2 by using a so-called insert molding method (that is, a method of pouring metal into the cavity of a mold in which the sleeve 3 is set in advance to form a nut body in which the sleeve 3 is incorporated) when molding the nut body 2.

[0017] And the sleeve 3 incorporated in the nut body 2 as described above is in a state where the fitting projection 11 formed at the upper end is fitted into the fitting recess 10 at the upper end of the fitting hole 9 of the nut body 2, so that it cannot be easily removed from the nut body 2. Also, the inner diameter of the sleeve 3 is slightly (about 1.0 mm) larger than the inner diameter of the bolt insertion hole 7 (the inner diameter of the engraved portion of the thread groove 8). Further, the lower part of the sleeve 3 is slightly (about 2.0 mm, that is, about half of the thickness of the steel plate to be welded) below the respective protruding bodies 6, 6... provided on the lower surface of the flange portion 5 of the nut body 2. Protruding It is in a state of protruding slightly downward.

[0018] <Usage and Function of Welding Nut> Figure 5 shows the method of using the welding nut 1 configured as described above. When welding the welding nut 1 to a steel plate as the adherend, as shown in Fig. 5(a), the lower end portion of the sleeve 3 is fitted (inserted) into the bolt insertion hole B drilled in the steel plate P. By fitting the lower end portion of the sleeve 3 into the bolt insertion hole B of the steel plate P in this way, the welding nut 1 can be accurately positioned at the position to be welded.

[0019] And, as described above, after accurately positioning the welding nut 1 on the adherend, projection welding is performed. That is, with the positive and negative electrodes grounded on the outer periphery of the nut body 2 and the surface or back side of the steel plate P, respectively, a predetermined voltage is applied while applying a pressure in the direction of the steel plate P (i.e., vertically downward) to the welding nut 1 to energize. When energized in this way, the current is transmitted to the steel plate P through the protrusions 6, 6,... on the lower surface of the flange portion 5 of the nut body 2. And at that time, since the protrusions 6, 6,... melt due to heat generated by the electrical resistance, the nut body 2 is fixed to the steel plate P (i.e., point welded).

[0020] As described above, when projection welding is performed, the melted protrusions 6, 6,... are leveled on the lower surface of the flange portion 3 of the nut body 2, and the nut body 2 is fixed to the steel plate P over a large area. Also, even if a situation occurs where the melted metal flows unevenly and mostly toward the center when the protrusions 6, 6,... melt, it is blocked by the sleeve 3, so that the situation of entering into the bolt insertion hole B does not occur.

[0021] Fig. 5(b) shows the state where the welding nut 1 is welded to the steel plate P. In the bolt insertion hole B of the steel plate P to which the welding nut 1 is welded, the sleeve 3 is located inside and also functions as a guide for guiding the tip of a bolt (not shown) into the bolt insertion hole 7 of the nut body 2.

[0022] <Effect of the welding nut><000****>As described above, the welding nut 1 has a cylindrical nut body 2 with a bolt insertion hole 7 drilled in it, and a flange portion 5 is integrally provided on the outer circumference of the lower end of the nut body 2. Projections 6, 6... are provided on the lower surface of the flange portion 5 so as to protrude downward, and a sleeve 3 made of insulating material having an inner diameter larger than the inner diameter of the bolt insertion hole 7 is provided inside the lower end of the nut body 2 so as to protrude from the lower end of the nut body 2. Therefore, with the welding nut 1, when projection welding, the sleeve 3 can be fitted into the bolt insertion hole B drilled in the steel plate P to accurately position it at the welding location, and the sleeve 3 can effectively prevent the molten projections 6, 6... from entering the bolt insertion hole 7 of the nut body 2.

[0023] Furthermore, since the welding nut 1 has a sleeve 3 integrally formed with the nut body 2 by insert molding, it can be manufactured inexpensively and easily.

[0024] Furthermore, since the welding nut 1 has a fitting projection (engaging means) 11 formed on the upper edge of the outer circumference of the sleeve 3 to prevent it from falling off the nut body 2, it is possible to effectively prevent the sleeve 3 from unintentionally detaching from the nut body 2.

[0025] <Examples of changes to welding nuts> The welding nut according to the present invention is not limited in any way to the embodiments described above, and the material, shape, structure, and other configurations of the nut body and sleeve can be appropriately changed as necessary without departing from the spirit of the present invention. For example, the welding nut according to the present invention is not limited to having six protrusions formed on the back surface of the flange portion as in the above embodiment, but may have five or fewer or seven or more protrusions. Furthermore, the protrusions are not limited to being substantially frustoconical as in the above embodiment, but can be changed to pointed cones, prismatics, pyramidal shapes, or frustoconical shapes, etc.

[0026] Furthermore, the welding nut according to the present invention is not limited to having a sleeve made of polyimide (PI) as in the above embodiment, but may also have a sleeve made of a heat-resistant synthetic resin other than polyimide, such as polyetheretherketone (PEEK) or polyphenylene sulfide (PPS), or a sleeve made of ceramics, etc.

[0027] Furthermore, the welding nut according to the present invention is not limited to the embodiment described above, in which a flange portion is provided at the lower end of the nut body and a projection is formed on the lower surface (back surface) of the flange portion. It may also be a prism-shaped engaging portion in which a projection is formed on the lower surface, etc.

[0028] In addition, the welding nut according to the present invention is not limited to having a sleeve protrusion of approximately 2.0 mm from the lower end of the nut body (the tip of the projection), as in the above embodiment, and the amount of protrusion can be appropriately changed according to the thickness of the workpiece, such as a steel plate, to be welded. Furthermore, the welding nut according to the present invention is not limited to having a sleeve inner diameter that is approximately 1.0 mm larger than the inner diameter of the bolt insertion hole (the inner diameter of the threaded portion of the screw groove), as in the above embodiment, and the difference between the inner diameter of the sleeve and the inner diameter of the bolt insertion hole can be appropriately changed as needed. By adjusting the difference between the inner diameter of the sleeve and the inner diameter of the bolt insertion hole to less than 2.0 mm, it is possible to effectively prevent the formation of unnecessary cavities between the bolt being fastened and the bolt insertion hole in the steel plate, which can cause rust. [Industrial applicability]

[0029] As the welding nut according to the present invention exhibits the excellent effects described above, it can be suitably used as a fastening member for fastening to a bolt by welding it to a workpiece such as a steel plate. [Explanation of Symbols]

[0030] 1. Welding nuts 2. Nut body 3 sleeves 5. Flange section 6... protrusion 7. Bolt insertion hole 8. Screw grooves 9. Fitting groove 10. Fitting recess 11. Engaging projection (engaging means) P Steel plate (adherent) B. Bolt insertion hole

Claims

1. A welding nut that is welded onto a metal plate by projection welding, A cylindrical nut body, formed by drilling a bolt insertion hole, has a circular flange integrally provided on its outer circumference near the lower end, and a projection is provided on the lower surface of the flange so as to protrude downward, and a sleeve made of insulating material having an inner diameter larger than the inner diameter of the bolt insertion hole is provided inside the lower end of the nut body so as to protrude from the lower end of the nut body, and The projections are conical, frustoconical, pyramidal, or frustoconical in shape, and are provided at equal intervals along the outer peripheral edge of the lower surface of the flange portion, and further, The sleeve is made of one of the following: polyimide, polyetheretherketone, or polyphenylene sulfide. An engaging means for preventing the nut from falling off is formed in a band shape on the upper edge of the outer circumference of the sleeve, with a larger diameter than the lower part, and the lower surface of the engaging means is inclined. A welding nut characterized in that the difference between the inner diameter of the sleeve and the inner diameter of the bolt insertion hole in the nut body is adjusted to be less than 2.0 mm.

2. The welding nut according to claim 1, characterized in that the sleeve is integrally formed with the nut body by insert molding.

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