Stud bolt structure

Abstract

To provide a tight-fitting stud bolt structure capable of preventing a floating phenomenon of a nut to be reliably tightened to a stud bolt, especially suitable for use in a battery protection unit of a power storage system.SOLUTION: A stud bolt structure employs such technical means as to: press-fit a head part 21 of a stud bolt 2 into a hole part 11 of a plate body 1; fix the edge part of the hole part 11 to an inner part of an annular groove 24 in an engaged state; cause a shaft part 22 formed with a thread 25 to protrude from an apparatus fixation surface 12A of the plate body 1; cause the apparatus fixation surface 12A and an outside surface 23A of an annularly protruding part 23 of the stud bolt 2 to be continuous flush with each other; cause a surface 12B of the plate body 1 and an outside surface 21A of the head part 21 of the stud bolt 2 to be continuous flush with each other; and screw the nut 3 and the stud bolt 2 together to support the fitting therebetween in a firmly tightening state where a contact surface 31 of the nut 3 and the apparatus fixation surface 12A tightly contact with each other.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an improvement in a stud bolt structure, and more particularly, to a stud bolt structure that can prevent the nut from lifting and can be firmly tightened to the stud bolt, and is particularly suitable for use in a battery protection unit of a power storage system.

Background Art

[0002] In recent years, the demand for storage batteries in various applications has been expanding towards the realization of "carbon neutrality", and a power storage system configured by incorporating a storage battery board, a control board, etc. inside a container body has been adopted.

[0003] In such a battery protection unit (BPU: Battery-Protector-Unit) of a power storage system, since the housing of the container body is made of a thin metal plate, a press-fit type stud bolt structure has been conventionally known as a structure for fixing devices such as a control base device to the surface of such a thin metal plate by screwing (see, for example, Patent Document 1).

[0004] By the way, in the stud bolt described in this <Patent Document 1>, in order to obtain sufficient strength for allowing the plastic deformation part at the edge of the hole in the plate material to enter only the annular groove, a structure of thickening the annular protrusion is adopted (see paragraphs

[0010] and [FIG. 2] of the specification).

[0005] However, in such a structure, when the stud bolt is press-fitted, the annular protrusion inevitably protrudes from the surface of the plate material. Therefore, when a nut is screwed onto the threaded part of the stud bolt, due to the presence of the protruding part of this annular protrusion, that is, the "non-threaded part of the thread", even if the nut is tightened, there is a problem that the contact surface of the nut floats from the metal plate and a gap is generated.

[0006] In addition, in other general stud bolt structures, when the bolt is press-fitted and fixed to the metal plate, due to the impact or overpressure during processing, the periphery of the hole in the metal plate warps and a burr-like surplus portion is generated. Due to the interference of this surplus portion, there is still a problem that when the nut is tightened, the contact surface of the nut floats up from the metal plate and a gap is generated.

[0007] As a result, there is a risk that the nut will become loose easily, and there is a risk that the surface of the metal plate and the contact surface of the nut will not be in sufficient close contact. In particular, when it is adopted in the housing of the power storage system, since it is necessary to fix devices such as the control board device with nuts made of insulators, there is a risk of electric leakage due to loosening or floating of the nuts, leading to the risk of electric shock accidents and damage to devices.

[0008] In addition, the bolt described in <Patent Document 1> is formed by a known forging method in order to increase the thickness of the annular protrusion. That is, since it is necessary to use a metal material with low hardness in order to adopt the forging method, conversely, since the thickness of the annular protrusion cannot be formed small, it is difficult to solve the problem due to the interference of the protrusion of the annular protrusion described above.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] The present invention has been made in view of the above problems in the conventional stud bolt structure, and its object is to prevent the nut from floating and to be able to firmly tighten the stud bolt. In particular, it is to provide a high-adhesion stud bolt structure suitable for use in the battery protection unit of the power storage system.

Means for Solving the Problems

[0011] The means adopted by the present inventor to solve the above technical problems will be described with reference to the accompanying drawings as follows.

[0012] That is, the present invention is a stud bolt structure in which a nut 3 is supported by a structure in which a stud bolt 2 made of hard stainless steel is fixed to a metal plate body 1, while a circular hole portion 11 is formed in the plate body 1, the stud bolt 2 forms a head portion 21 having a flange shape and a non-circular cross section at one end of a shaft portion 22, and a thin annular protrusion 23 is integrally formed on the outer peripheral surface of the shaft portion 22 in the vicinity of the head portion 21, and an annular groove 24 is formed between the annular protrusion 23 and the head portion 21, and a thread 25 is formed on the outer peripheral surface of the shaft portion 22 from the annular protrusion 23 to the tip, the head portion 21 of the stud bolt 2 is press-fitted into the hole portion 11 of the plate body 1 and fixed in a state where the edge portion of the hole portion 11 is fitted inside the annular groove 24, and the shaft portion 22 on which the thread 25 is formed is projected onto the equipment fixing surface 12A of the plate body 1, the equipment fixing surface 12A and the outer side surface 23A of the annular protrusion 23 of the stud bolt 2 are made continuous on the same plane, and the surface 12B of the plate body 1 and the outer side surface 21A of the head portion 21 of the stud bolt 2 are made continuous on the same plane, By adopting the technical means of screwing the nut 3 and the stud bolt 2 together and supporting them in a tightened state where the contact surface 31 of the nut 3 is in close contact with the equipment fixing surface 12A, the stud bolt structure is completed.

[0013] In addition, in order to solve the above problems, the present invention can also adopt, if necessary, in addition to the above means, the technical means of forming the stud bolt 2 by cutting a hard stainless steel material.

[0014] Furthermore, in order to solve the above problems, the present invention can also adopt a technical means of setting the thickness of the annular protrusion 23 of the stud bolt 2 to 0.2 mm in addition to the above means as necessary.

[0015] Furthermore, in order to solve the above problems, the present invention can also adopt a technical means of forming the nut 3 into an insulating double-threaded nut formed of an insulator and fixing a device to the opposite surface side of the contact surface 31 in addition to the above means as necessary.

[0016] Furthermore, in order to solve the above problems, the present invention can also adopt a technical means of forming serrated uneven portions 21B on the periphery of the head 21 of the stud bolt 2 in addition to the above means as necessary.

Advantages of the Invention

[0017] In the present invention, by adopting hard stainless steel as the material of the stud bolt, high strength can be imparted even if the annular protrusion is formed thinly. Moreover, by making the equipment fixing surface of the plate body and the outer surface of the annular protrusion of the stud bolt continuous on the same plane, it is possible to prevent the nut from lifting and ensure firm tightening.

[0018] The stud bolt structure of the present invention can prevent electric shock accidents and damage to devices such as the control base device, especially when used in the battery protection unit of the power storage system, so it has high industrial utility value.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0020] Embodiments of the present invention will be described with reference to FIGS. 1 to 5. The present invention is a stud bolt structure (clenching stud structure) in which a nut 3 is supported by a structure in which a stud bolt 2 made of hard stainless steel is fixed to a metal plate body 1.

[0021] As the metal material used for the plate body 1 in the present embodiment, for example, a highly corrosion-resistant plated steel sheet containing zinc, aluminum, and magnesium can be adopted. Further, a circular hole portion 11 is formed in the plate body 1. In the present embodiment, the thickness of the plate body 1 is set to about 1.6 mm, and the diameter of the hole portion 11 is set to about 6 mm (+0.8 mm / -0 mm).

[0022] As the hard stainless steel material adopted for the stud bolt 2, for example, SUS420F can be adopted, and the Vickers hardness (HV) is preferably 450 to 550 HV (depth 0.05 mm). At this time, the hardness difference from the plate body 1 is preferably 30 or more in Rockwell hardness (HRB). Further, the stud bolt 2 is preferably heat-treated by vacuum carburizing quenching and tempering, and passivation treatment is appropriately performed on the surface.

[0023] And, the stud bolt 2 forms a head portion 21 having a flange shape and a non-circular cross section at one end portion of the shaft portion 22 (see FIGS. 1 and 2). In the present embodiment, a saw blade-shaped uneven portion 21B can be formed on the peripheral edge of the head portion 21 of the stud bolt 2. By doing so, the rotation of the stud bolt 2 can be prevented.

[0024] Next, a thin-walled annular protrusion 23 is integrally formed on the outer peripheral surface of the shaft portion 22 in the vicinity of the head portion 21. In the present embodiment, the head portion 21 and the annular protrusion 23 are in a parallel relationship, and the thickness of the annular protrusion 23 of the stud bolt 2 is formed to be about 0.2 mm (near the limit of the balance between strength and cutting process).

[0025] Also, an annular groove 24 is formed between the annular protrusion 23 and the head portion 21, and a thread 25 is formed on the outer peripheral surface of the shaft portion 22 from the annular protrusion 23 to the tip. In the present embodiment, the thickness of the head portion 21 is about 0.7 mm, and the axial width of the annular groove 24 is about 0.7 mm. Further, the protruding height of the outer periphery of the annular protrusion 23 is made substantially equal to the height of the outer diameter of the thread 25 of the shaft portion 22 (about 0.5 mm).

[0026] In the present embodiment, the stud bolt 2 can be formed by cutting the above-described hard stainless steel material. By adopting cutting, higher dimensional processing accuracy can be achieved, which is different from the forging method.

[0027] Then, as shown in FIG. 3, the head portion 21 of the stud bolt 2 is press-fitted into the hole portion 11 of the plate body 1, and fixed in a state where the edge portion of the hole portion 11 is fitted into the annular groove 24, and the shaft portion 22 formed with the thread 25 is made to protrude from the equipment fixing surface 12A of the plate body 1.

[0028] In the present embodiment, in order to fix the stud bolt 2 to the plate body 1, for example, the following known method is used. First, the shaft portion 22 of the stud bolt 2 is inserted through the hole portion 11 of the plate body 1. Next, while being supported by a cylindrical jig from the back side (equipment fixing surface 12A) of the plate body 1, the head portion 21 is pushed in by a hydraulic press or the like and press-fitted into the plate body 1.

[0029] Then, while pressing the head 21 into the plate body 1, the periphery of the hole 11 of the plate body 1 undergoes elastic deformation or plastic deformation and enters and fits into the annular groove 24. Then, by removing the jig that has been supporting, the shaft portion 22 of the stud bolt 2 can be fixed so as to protrude from the equipment fixing surface 12A of the plate body 1.

[0030] In the stud bolt structure manufactured and processed in this way, the equipment fixing surface 12A and the outer surface 23A of the annular protrusion 23 of the stud bolt 2 are continuous on the same plane, and the surface 12B of the plate body 1 and the outer surface 21A of the head 21 of the stud bolt 2 are continuous on the same plane (see Fig. 4).

[0031] Then, the nut 3 and the stud bolt 2 are screwed together and supported in a tightened state where the contact surface 31 of the nut 3 is in close contact with the equipment fixing surface 12A. In this embodiment, when the nominal diameter of the thread of the stud bolt 2 is 6 (M6), the tightening torque is set to 0.5 kN or more.

[0032] In this way, since the equipment fixing surface 12A of the plate body 1 and the outer surface 23A of the annular protrusion 23 of the stud bolt 2 are continuous on the same plane, when the nut 3 is tightened, no minute gap is generated on the contact surface 31, and it can be made to closely adhere to the equipment fixing surface 12A, reliably preventing lifting.

[0033] Then, in this embodiment, the nut 3 is made into an insulating double-threaded nut formed of an insulator (such as glass fiber-reinforced polyester, glass fiber-reinforced polyamide, etc.), and equipment such as a control base device can be fixed to the opposite surface side of the contact surface 31, and a battery protection unit of the power storage system can be configured. Also, the threaded portion inside the nut 3 can be provided by embedding metal bag nuts 32 respectively (see Fig. 5). Since the bag nuts 32 do not penetrate, even if they are made of a conductive metal or other material, the insulating function of the nut 3 is not impaired.

[0034] The present invention is generally configured as described above, but the present invention is by no means limited to the illustrated embodiments, and various modifications are possible within the scope of the claims. For example, the shape of the head 21 of the stud bolt 2 is not limited to a saw blade shape as long as it has a non-circular cross-section, and can be other shapes, and belongs to the technical scope of the present invention.

Explanation of Signs

[0035] 1 Plate body 11 Hole portion 12A Equipment fixing surface 12B Surface 2 Stud bolt 21 Head 21A Outer surface 21B Concavo-convex portion 22 Shaft portion 23 Annular protrusion 23A Outer surface 24 Annular groove 25 Thread 3 Nut 31 Contact surface 32 Socket nut

Claims

1. A stud bolt structure in which a nut is supported on a structure in which a stud bolt made of hard stainless steel is fixed to a metal plate body, wherein a circular hole is formed in the plate body, the stud bolt has a flange-shaped and non-circular cross-section head formed at one end of the shaft portion, and a thin-walled annular protrusion is integrally formed on the outer peripheral surface of the shaft portion in the vicinity of this head. An annular groove is formed between the annular protrusion and the head, and a thread is formed on the outer peripheral surface of the shaft portion from the annular protrusion to the tip, the head of the stud bolt is press-fitted into the hole of the plate body and fixed in a state where the edge of the hole is fitted inside the annular groove, and the shaft portion with the thread formed thereon protrudes from the equipment fixing surface of the plate body, the equipment fixing surface and the outer surface of the annular protrusion of the stud bolt are continuous on the same plane, and the surface of the plate body and the outer surface of the head of the stud bolt are continuous on the same plane, the nut and the stud bolt are screwed together, and the stud bolt structure is characterized in that it is supported in a tightened state where the contact surface of the nut is in close contact with the equipment fixing surface.

2. The stud bolt structure according to claim 1, wherein the stud bolt is formed by cutting a hard stainless steel material.

3. The stud bolt structure according to claim 1, wherein the thickness of the annular protrusion of the stud bolt is 0.2 mm.

4. The stud bolt structure according to claim 1, wherein the nut is an insulating double-threaded nut formed of an insulator, and equipment is fixed on the opposite side of the contact surface.

5. The stud bolt structure according to claim 1, wherein saw-tooth-shaped uneven portions are formed on the peripheral edge of the head of the stud bolt.

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