Threaded hole processing method

Abstract

The method for machining a threaded hole in a workpiece having a plate-like portion (1) comprises: a step of preparing a flat auxiliary component (2); a step of forming a first pre-hole having an inner diameter smaller than the outer diameter of the threaded hole in the plate-like portion (1); a step of forming a second pre-hole having an inner diameter smaller than the outer diameter of the threaded hole in the auxiliary component (2); a step of fixing the plate-like portion (1) to the auxiliary component (2) in such a manner that the first pre-hole and the second pre-hole are concentric; and a step of forming threaded holes (10, 20) in the plate-like portion (1) and the auxiliary component (2) by inserting a tap through the first pre-hole and the second pre-hole.

Description

Technical Field

[0001] The present disclosure relates to a method for machining a threaded hole in a plate-shaped portion of a workpiece. Background Art

[0002] When a threaded hole (internal threaded portion) is formed in a thin plate-shaped portion of a workpiece, a method is generally used in which a through hole is formed in the portion, and a welding nut is joined by welding in a state in which the center of the through hole is aligned with the center of the threaded hole (for example, refer to Japanese Patent Gazette No. 2012-82890 (Patent Document 1)).

[0003] Alternatively, a method is used in which a through hole is formed in a thin plate-shaped portion and a nut is rivet-fastened around the periphery of the through hole for mounting (for example, refer to Japanese Patent Application Laid-Open No. 2004-148341 (Patent Document 2)).

[0004] Patent Document 1: Japanese Patent Application Publication No. 2012-82890

[0005] Patent Document 2: Japanese Patent Application Publication No. 2004-148341 Summary of the invention

[0006] Problems to be solved by the invention

[0007] The method of joining weld nuts requires welding work, so there is a concern that the number of steps will increase. In particular, when the workpiece is formed of a galvanized steel sheet, there is a problem that the welding workability is reduced because of the generation of pore defects and spatter during the welding work.

[0008] On the other hand, the method of installing the rivet nut has a concern that the nut may rotate idly due to the specified torque depending on the installation state. In order to prevent the nut from rotating idly, the nut needs to be welded, which is a concern. In addition, the damaged welded part needs to be plated, which is a concern that the number of steps will increase.

[0009] The present disclosure is made to solve such problems, and an object of the present disclosure is to provide a threaded hole processing method capable of forming a threaded hole in a plate-shaped portion of a workpiece with a simple structure.

[0010] Means for solving problems

[0011] In certain aspects of the present disclosure, in a method for processing a threaded hole in a workpiece having a plate-like portion, the method comprises: a step of preparing a flat auxiliary component; a step of forming a first pre-hole having an inner diameter smaller than the outer diameter of the threaded hole in the plate-like portion; a step of forming a second pre-hole having an inner diameter smaller than the outer diameter of the threaded hole in the auxiliary component; a step of fixing the auxiliary component to the plate-like portion in a manner such that the first pre-hole and the second pre-hole are concentric; and a step of forming threaded holes in the plate-like portion and the auxiliary component by inserting a tap through the first pre-hole and the second pre-hole.

[0012] Effects of the Invention

[0013] According to the present disclosure, a screw hole can be machined in a plate-shaped portion of a workpiece with a simple configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is an external view of a workpiece to which the threaded hole machining method according to the present embodiment is applied.

[0015] Figure 2 It is along Figure 1 A schematic cross-sectional view of a portion taken along line II-II.

[0016] Figure 3 This is a diagram showing the relationship between the thickness of the plate-shaped portion of the workpiece and the outer diameter of the screw hole that can be formed.

[0017] Figure 4 It is a figure for demonstrating the screw hole processing method of this embodiment.

[0018] Figure 5 It is a figure for demonstrating the screw hole processing method of this embodiment.

[0019] Figure 6 It is a figure for demonstrating the screw hole processing method of this embodiment. DETAILED DESCRIPTION

[0020] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, in the following, the same reference numerals are attached to the same or corresponding parts in the drawings, and the description thereof will not be repeated in principle.

[0021] Figure 1 This is an external view of a workpiece to which the threaded hole machining method according to the present embodiment is applied. Figure 2 It is along Figure 1 A schematic cross-sectional view of a portion taken along line II-II.

[0022] Reference Figure 1The workpiece W has a plate-like portion 1. The plate-like portion 1 constitutes at least a portion of the workpiece W. The plate-like portion 1 is a metal plate having a flat plate shape, and has a first surface 1A and a second surface 1B opposite to the first surface 1A. The plate-like portion 1 is formed of, for example, a hot-dip galvanized steel sheet. The thickness H1 of the plate-like portion 1 is about 1.5 mm to 3 mm.

[0023] The workpiece W constitutes at least a part of a housing for accommodating an electric device, for example. The second surface 1B of the plate-shaped portion 1 may be a mounting surface for the electric device. The electric device may be fixed to the second surface 1B by placing the electric device on the second surface and fastening the screws.

[0024] The auxiliary member 2 is fixed to the first surface 1A of the plate-like portion 1. The auxiliary member 2 has a rectangular flat plate shape and has a smaller flat surface area than the plate-like portion 1.

[0025] like Figure 2 As shown, the auxiliary component 2 is fixed to the first surface 1A of the plate-like portion 1 by fastening components 3A and 3B. The fastening components 3A and 3B may be rivets, for example. The fastening components 3A and 3B may also be screws such as countersunk screws. In addition, when countersunk screws are used for the fastening components 3A and 3B, it is possible to suppress the protrusion of the screw head from the second surface 1B (mounting surface).

[0026] When rivets are used as the fastening members 3A and 3B, through holes are formed in advance in the plate-like portion 1 and the auxiliary member 2 .

[0027] In the method of fixing the auxiliary component 2 to the plate-like part 1, in addition to the method of fastening the auxiliary component 2 to the plate-like part 1, a method of bonding the auxiliary component 2 to the plate-like part 1, or a method of riveting the plate-like part 1 and the auxiliary component 2 can also be adopted.

[0028] Screw holes 10 and 20 are formed in the plate-like portion 1 and the auxiliary component 2, respectively. The screw holes 10 and 20 form internal threaded portions that are screwed into an external threaded portion not shown. Each screw hole (internal threaded portion) has peaks and valleys that are repeated at a certain interval. In this specification, the diameter D1 of a virtual cylinder connected to the valley bottom of the screw hole is also referred to as the "outer diameter", and the diameter D2 of a virtual cylinder connected to the top of the screw hole is referred to as the "inner diameter". The outer diameter D1 of the screw hole 10 is equal to the outer diameter D1 of the screw hole 20, and the inner diameter D2 of the screw hole 10 is equal to the inner diameter D2 of the screw hole 20.

[0029] like Figure 2As shown, the threaded hole 10 and the threaded hole 20 are concentrically arranged when the auxiliary component 2 is fixed to the plate-like portion 1. As described later, the threaded hole 10 and the threaded hole 20 can be formed integrally by performing tapping processing (Japanese: タップ processing) on ​​the auxiliary component 2 and the plate-like portion 1 when the auxiliary component 2 is fixed to the plate-like portion 1.

[0030] The auxiliary member 2 is fastened to the plate-like portion 1 at the first portion 2A and the second portion 2B arranged across the screw hole 20. The first portion 2A and the second portion 2B are preferably arranged at symmetrical positions across the screw hole 20. Figure 2 In the example of FIG. 2 , the first portion 2A and the second portion 2B are arranged at positions at an equal distance L1 from the center of the screw hole 20 .

[0031] Furthermore, the number of fastening portions between the auxiliary member 2 and the plate-shaped portion 1 may be three or more. Even when the number of fastening portions is three or more, the three or more fastening portions are preferably provided at positions equidistant from the center of the screw hole 20 .

[0032] Here, when a threaded hole is formed in the plate-shaped portion 1 of the workpiece W, there is a difference between the thickness H1 of the plate-shaped portion 1 and the outer diameter D1 of the threaded hole that can be formed. Figure 3 The relationship shown. Figure 3 The vertical axis represents the thickness H1 of the plate-like portion 1 , and the horizontal axis represents the outer diameter D1 of the threaded hole. Figure 3 This is a graph plotting the upper limit of the outer diameter of a screw hole that can be formed with respect to the thickness H1 of a hot-dip galvanized steel sheet. Figure 3 The relationship shown can be established in advance with respect to the plate-shaped portion 1 of the workpiece W through preliminary experiments.

[0033] Figure 3 In the example of FIG. 1 , as the thickness H1 of the plate-like portion 1 becomes thinner, the upper limit value of the outer diameter D1 of the screw hole that can be formed in the plate-like portion 1 becomes smaller.

[0034] On the other hand, when the workpiece W constitutes the housing of an electric device, it is required to reduce the thickness H1 of the plate-shaped portion 1 from the viewpoint of reducing the weight of the electric device. For example, when the thickness H1 of the plate-shaped portion 1 is about 2 to 3 mm, the upper limit of the outer diameter D1 of the threaded hole that can be formed in the plate-shaped portion 1 is about 4 to 5 mm. Therefore, in order to ensure the strength of the installation of the electric device, there is a problem that an external thread with a larger outer diameter cannot be used.

[0035] Generally, in order to form a threaded hole having an outer diameter larger than an upper limit value in a thin metal plate, a method of joining a weld nut to the metal plate by welding and a method of attaching a nut to the metal plate by caulking are used.

[0036] However, in the method using the weld nut, since welding work for joining the weld nut is necessary, there is a concern that the number of steps may increase. In particular, when the metal plate is formed of a galvanized steel plate, there is a problem that welding workability is reduced due to the generation of porosity defects and spatter during the welding work.

[0037] In the method of installing by riveting nuts, there is a case where the nut may idle due to the specified torque depending on the installation state. In order to prevent the nut from idling, the nut needs to be welded. In addition, the damaged welded part needs to be plated, which may increase the number of steps. Moreover, in the method of installing by riveting nuts on metal plates, the ends on the nut side and the opposite side protrude from the surface of the metal plate, so there is a case where the installation of electrical equipment relative to the surface is hindered.

[0038] Therefore, in this embodiment, if Figure 1 as well as Figure 2 As shown, by partially fixing the flat plate-like auxiliary member 2 to the portion where the screw hole 10 is formed in the plate-like portion 1, the thickness of the screw hole capable of forming a desired outer diameter is achieved.

[0039] Below, use Figures 4 to 6 , the threaded hole processing method of this embodiment is described.

[0040] Reference Figure 4 First, a workpiece W and an auxiliary component 2 are prepared. A pre-hole 12 is formed in the plate-shaped portion 1 of the workpiece W at the position where the threaded hole 10 is formed. Through holes 14A and 14B for fastening the auxiliary component 2 are also formed in the plate-shaped portion 1. The inner diameter of the pre-hole 12 is less than the inner diameter of the threaded hole 10.

[0041] A pre-hole 22 is formed in the auxiliary member 2 at the position where the threaded hole 20 is formed. Through holes 24A and 24B for fastening the plate-like portion 1 are also formed in the auxiliary member 2. The inner diameter of the pre-hole 22 is smaller than the inner diameter of the threaded hole 20 (ie, the inner diameter of the threaded hole 10).

[0042] Here, the thickness H2 of the auxiliary member 2 is determined based on the outer diameter of the screw hole 10 and the thickness H1 of the plate-like portion 1. Figure 3The relationship shown determines the thickness H* of the plate-like part 1 required to form a threaded hole with a desired outer diameter D1. For example, in the case of forming a threaded hole 10 with an outer diameter of 10 mm, the required thickness H* of the plate-like part 1 is about 4.5 mm. Therefore, the thickness H2 of the auxiliary component 2 is set in such a way that the total of the actual thickness H1 of the plate-like part 1 and the thickness H2 of the auxiliary component 2 (H1+H2) is greater than the required thickness H* of the plate-like part 1. That is, the thickness H2 of the auxiliary component 2 is greater than the difference (=H*-H1) between the actual thickness H1 of the plate-like part 1 and the required thickness H* of the plate-like part 1. For example, in the case where the thickness H1 of the plate-like part 1 is 2.3 mm, in order to form a threaded hole 10 with an outer diameter D1=10 mm, the thickness H2 of the auxiliary component 2 is set in such a way that H2≥2.2 mm is satisfied.

[0043] like Figure 4 As shown, the through holes 14A, 14B of the plate-like portion 1 and the through holes 24A, 24B of the auxiliary component 2 are formed overlapping each other when the auxiliary component 2 is placed on the first surface 1A of the plate-like portion 1 so that the pre-holes 12 and the pre-holes 22 are concentrically arranged.

[0044] Next, refer to Figure 5 , the auxiliary component 2 is fixed to the plate-like part 1. Figure 5 In the example, the auxiliary component 2 is fastened to the plate-like portion 1 using the fastening members 3A and 3B. When rivets are used as the fastening members 3A and 3B, the first rivet is inserted through the through hole 14A and the through hole 24A, and the second rivet is inserted through the through hole 14B and the through hole 24B. The auxiliary component 2 can be fastened to the plate-like portion 1 by riveting the first and second rivets.

[0045] In addition, although not shown in the figure, when the fastening members 3A and 3B use threads, the formation of the through hole can be omitted. However, when the fastening members 3A and 3B use countersunk screws, it is necessary to form a countersunk hole in the second surface 1B of the plate-like portion 1 to accommodate the head of the countersunk screw.

[0046] Next, refer to Figure 6 The tap 50 is inserted through the pre-hole 12 and the pre-hole 22, and tapping is performed on the inner side of the pre-holes 12 and 22. The tap 50 and the tapping process can use the known contents. Figure 2 The threaded holes 10 and the threaded holes 20 are shown.

[0047] As described above, according to the threaded hole processing method of this embodiment, a threaded hole can be formed in a plate-like portion of a workpiece without using welding. Thus, a threaded hole can be easily formed even in a plate-like portion formed of a material that is difficult to process by welding. In addition, since there is no need to install a rivet nut, it is possible to avoid the nut from spinning idle.

[0048] The embodiments disclosed this time should be understood in all respects as illustrative and non-restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

[0049] Description of Reference Numerals

[0050] 1 plate-like part, 2 auxiliary component, 3A, 3B fastening component, 10, 20 threaded holes, 12, 22 pre-holes, 14A, 14B, 24A, 24B through holes, 50 tap, W workpiece.

Claims

1. A threaded hole machining method for machining a threaded hole in a workpiece having a plate-like portion, wherein: The threaded hole processing method comprises: The step of preparing a flat plate-shaped auxiliary component; a step of forming a first pre-hole having an inner diameter smaller than an outer diameter of the threaded hole in the plate-shaped portion; a step of forming a second pre-hole having an inner diameter smaller than an outer diameter of the threaded hole in the auxiliary component; The step of fixing the auxiliary component to the plate-like portion in such a manner that the first pre-hole and the second pre-hole are concentric; as well as The step of forming the threaded hole in the plate-like portion and the auxiliary component by inserting a tap through the first pre-hole and the second pre-hole, The step of preparing the auxiliary component in the form of a plate comprises: A step of determining a total thickness of the plate-like portion and the auxiliary component based on an outer diameter of the threaded hole; and A step of preparing the auxiliary member having a thickness corresponding to a difference between the total thickness and the thickness of the plate-shaped portion.

2. The threaded hole machining method according to claim 1, wherein: The step of fixing the auxiliary member to the plate-shaped portion includes the step of fastening the auxiliary member to the plate-shaped portion at a first portion and a second portion, the first portion and the second portion being portions arranged with the first pre-hole and the second pre-hole interposed therebetween.

3. The threaded hole machining method according to claim 2, wherein: The step of fastening the auxiliary member to the plate-shaped portion further includes the step of arranging the first portion and the second portion at symmetrical positions with the second pre-hole interposed therebetween.

4. The threaded hole machining method according to claim 3, wherein: The step of fastening the auxiliary component to the plate-shaped portion includes the step of fastening the auxiliary component to the plate-shaped portion using rivets.

5. The threaded hole machining method according to claim 2, wherein: The step of fastening the auxiliary component to the plate-shaped portion includes the step of fastening the auxiliary component to the plate-shaped portion using rivets.

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