WO2015012236A1 - Metal plate with tapped hole, frame, and method for manufacturing metal plate with tapped hole - Google Patents

Abstract

In the metal plate with a tapped hole, the tapped hole is provided with a cylindrical outer wall section that rises from one surface of the metal plate and a cylindrical inner wall section, which is folded back from the edge of the outer wall section on the inside of the outer wall section. A female screw is formed on the inner circumferential surface of the inner wall section.

Description

Metal plate with screw hole, housing, and method for manufacturing metal plate with screw hole

The present invention relates to a metal plate with a screw hole, a housing, and a manufacturing method of the metal plate with a screw hole. More specifically, a metal plate with a screw hole that has a screw hole excellent in fastening force with a male screw and can prevent the screw hole from being damaged, and a housing having the metal plate with the screw hole even when the thickness is reduced And a method of manufacturing the metal plate with screw holes.
This application claims priority based on Japanese Patent Application No. 2013-154105 for which it applied to Japan on July 25, 2013, and uses the content here.

The metal plates processed into various shapes by cutting and bending are often used for the outdoor units of air conditioners and the housing of substation equipment. Since a screw structure is widely used for the attachment part of this type of metal plate and other metal plates and accessory parts constituting the housing, a screw hole may be formed in the metal plate.

FIG. 11 is a diagram schematically showing a screw hole included in a conventional metal plate, and is a vertical cross-sectional view when seen in a cross section including the central axis of the screw hole. In the drawing, a metal plate 510 having a screw hole is shown. However, in order to facilitate understanding of the configuration, a male screw 550 and another metal plate 551 having a through hole 551a are further illustrated with imaginary lines. Show. The metal plate 510 shown in the figure has a cylindrical vertical wall portion 511 that functions as a screw hole (hereinafter, this vertical wall portion 511 may be referred to as a screw hole 511). One end of the vertical wall portion 511 is continuous with the main body 513 of the metal plate, and an internal thread 511b is formed on the inner peripheral surface. When the metal plate 551 having the through hole 551a is attached to the metal plate 510 in an overlapping manner, the male plate 550 is inserted into the through hole 551a and screwed into the screw hole 511 to be coupled. The screw hole 511 is frequently used because it can be formed in a metal plate using burring and is the easiest to process.

FIG. 12A and FIG. 12B are longitudinal sectional views schematically showing an example of a process for forming a screw hole in a conventional metal plate, FIG. 12A shows a drilling step, and FIG. 12B shows a burring step. In processing the screw hole 511, first, a pilot hole is made in the metal plate 520 to be processed. Drilling of the pilot hole can be performed by shearing or cutting. When making a pilot hole by shearing, for example, a punch 531 and a die 532 for drilling as shown in FIG. 12A are used. By bringing the punch 531 and the die 532 relatively close to each other, a part of the metal plate 520 is pushed into the through hole of the die 532 together with the punch 531. As a result, a part of the metal plate 520 is cut out and separated by blades provided on the punch 531 and the die 532, respectively, thereby making a pilot hole.

An elongated flange, which becomes a vertical wall portion, is formed on the metal plate 520 with a prepared hole by burring. For burring, as shown in FIG. 12B, a burring punch 533, a burring die 534, and a blank holder 539 are used. In the burring process, with the metal plate 520 sandwiched between the die 534 and the blank holder 539, the punch 533, the die 534 and the blank holder 539 are moved so as to be relatively close to each other, and the punch 533 and the bottom of the metal plate 520 are moved. The peripheral part of the hole is pushed into the recess of the die 534. As a result, the peripheral portion of the prepared hole of the metal plate 520 is expanded in the radial direction while being extended in the pushing direction of the punch 533, and as a result, a cylindrical extending flange, that is, the vertical wall portion 511 is formed.

The screw hole 511 can be formed in the metal plate 520 by processing the internal thread 511b using, for example, a tap (not shown) on the inner peripheral surface of the cylindrical vertical wall portion 511 formed in this way.

For example, as disclosed in Patent Document 1, various proposals have been made for screw holes in metal plates. The housing proposed in Patent Document 1 has a screw hole formed in the second sheet metal member among the constituent members. The screw hole of the second sheet metal member has a first flat plate portion and a second flat plate portion that are formed so that the end edges of the sheet metal member are folded and arranged opposite to each other. The screw hole of the second sheet metal member further protrudes in a cylindrical shape from the first flat plate portion and has a threaded portion on the inner peripheral surface, and protrudes in a cylindrical shape from the second flat plate portion and has an inner periphery. The surface has a threaded portion, and has a second cylindrical portion arranged substantially in series with the first cylindrical portion. According to the second sheet metal member, since the female screw is formed as a threaded portion on the inner peripheral surface of the first cylindrical portion and the second cylindrical portion, the axial dimension in contact with the male screw is lengthened to increase the tightening torque. It is explained that it can be secured.

Patent Document 2 discloses a first thin plate in which a first cylindrical portion is formed and a second thin plate in which a second cylindrical portion is formed, and the first cylindrical portion is provided in the second cylindrical portion. A structure in which the second thin plate is fastened to the first thin plate by screwing a tapping screw into the inner peripheral surface of the first cylindrical portion from the second thin plate side after being overlapped so as to be fitted coaxially is disclosed. Has been.

Japanese Unexamined Patent Publication No. 2011-214802 Japanese Unexamined Patent Publication No. 2012-241839

In the screw hole of the conventional metal plate 510 as shown in FIG. 11, a female screw 511b is formed on the inner peripheral surface of the vertical wall portion (extension flange) 511 formed by burring. Thus, in the screw hole 511 formed by burring, the fastening force with the male screw is reduced as the metal plate used for home appliances, automobile parts, and the like is required to be lighter. In addition, deformation of the screw hole 511 may cause the screw hole 511 and the male screw 550 not to mesh with each other, that is, the screw hole 511 may be damaged.

Moreover, in the above-mentioned patent document 1, it has a 1st flat plate part and a 2nd flat plate part which are mutually opposingly arranged as a screw hole, and the cylindrical part which has a screwing part in these 1st flat plate part and 2nd flat plate part. The structure which each provides is proposed. According to this configuration, it is described that a tightening torque can be secured by increasing the axial dimension of the female screw that contacts the male screw. When this screw hole is formed, a burring process is performed after making a pilot hole in the first flat plate part, and a burring process is performed after making a pilot hole in the second flat plate part. It is necessary to provide the cylindrical portion, then turn back so that the first flat plate portion overlaps the second flat plate portion, and further process the female screw. Thus, six steps are required for processing, and the number of processing is greatly increased. Further, when folding back so that the first flat plate portion overlaps the second flat plate portion, the centers of the two cylindrical portions need to coincide with each other, and high bending accuracy is required. From these, when the screw hole described in Patent Document 1 is processed into a metal plate, there is a problem that the processing cost is significantly increased.

Further, in the above-mentioned Patent Document 2, the paragraph number [0014] states that “the first cylindrical portion is inflated radially outward and pressed against the second cylindrical portion, so that the thin plates are firmly connected with the screw member without loosening. As described in ‘Fixed’, the play between the first tubular portion and the second tubular portion is eliminated, thereby aiming to prevent relative displacement between the first thin plate and the second thin plate. .
In this structure, if the dimensional difference between the inner diameter of the second cylindrical portion and the outer diameter of the first cylindrical portion is large, the second cylindrical shape can be sufficiently obtained even if the first cylindrical portion is expanded radially outward. As a result, the above-described effects may not be obtained. Therefore, in order to obtain a sufficient fastening force, it is desirable to reduce the above dimensional difference (play dimension) to some extent, but this time, the work of fitting the first cylindrical portion into the second cylindrical portion is performed. In some cases, the tapping screw may be accidentally screwed in even though it is not properly fitted. In such a case, of course, the first thin plate and the second thin plate cannot be reliably fixed. In addition, since it is common to provide a large number of screw holes of this kind, not only one, it is undeniable that the probability of such work mistakes is not low. Therefore, the structure of Patent Document 2 is not always sufficient from the viewpoint of reliably obtaining a sufficient fastening force.

The present invention has been made in view of the above circumstances, and is capable of reducing an increase in processing cost, and having a screw hole with excellent fastening force with a male screw even when the thickness is reduced, and capable of preventing the screw hole from being damaged. It aims at providing the metal plate with a hole, the housing | casing which comprises this metal plate with a screw hole, and also the manufacturing method of a metal plate with a screw hole.

In order to solve the above problem, the present inventors analyzed a decrease in screw fastening force and a phenomenon of breakage caused by thinning of the conventional metal plate described in FIG. 11, and the following (a) to (d): Got the factor.
(A) In the burring process, the base portion of the vertical wall portion 511 is thinned with the formation of the cylindrical vertical wall portion 511. The “root portion” means a portion 511a of the vertical wall portion 511 that is continuous with the metal plate main body 513 as shown by being surrounded by a two-dot chain line in FIG.
(B) Since the thread groove is processed up to the root portion where the thickness is reduced by the thinning of (a), a portion having a very thin thickness is generated.
(C) The part where the wall thickness is very thin is elastically deformed and the fastening force is reduced. Further, when the male screw 550 is screwed (tightened), plastic deformation may occur in a portion where the wall thickness is very thin, and the screw hole 511 may be damaged or may be broken.
(D) When the male screw 550 is screwed or loosened, the cylindrical vertical wall portion 511 is plastically deformed in the diameter increasing direction, and the area where the screw thread of the screw hole 511 contacts the screw thread of the male screw 550 is reduced. There is a case. In this case, the fastening force is reduced, and the screw hole 511 may be damaged.

As a result of diligent examination based on these phenomena, the present inventors have found that the screw hole is divided into a cylindrical outer wall portion rising from a metal plate and a cylindrical inner wall portion folded inward from the outer wall portion. It was conceived that a heavy wall was formed and a female screw was formed on the inner peripheral surface of the inner wall. Thereby, even when the thickness of the metal plate is reduced, the screw hole is excellent in fastening force with the male screw, and damage to the screw hole can be prevented.
In addition, as another aspect of the screw hole, the present inventors configure a double wall of a cylindrical inner wall portion that rises from a metal plate and a cylindrical outer wall portion that is folded outward from the inner wall portion. Further, it has been conceived that substantially the same effect can be obtained even in a configuration in which a female screw is formed on the inner peripheral surface of the inner wall portion.

The present invention has been completed based on the above findings, and the outline of the present invention is shown below.

(1) One aspect of the present invention is a metal plate having a screw hole, wherein the screw hole rises from one surface of the metal plate, and the outer wall extends from an edge of the outer wall portion. A metal plate with a screw hole, including a cylindrical inner wall portion folded inside the portion, and an internal thread formed on the inner peripheral surface of the inner wall portion.
(2) In the metal plate with a screw hole described in (1) above, the tip of the inner wall portion and the other surface of the metal plate may be flush with each other.
(3) In the metal plate with a screw hole according to (1), the outer peripheral surface of the inner wall portion is separated from the inner peripheral surface of the outer wall portion in a state where a male screw is not screwed into the female screw of the screw hole. In the state where the male screw is screwed to the female screw of the screw hole, at least a part of the outer peripheral surface of the inner wall portion abuts on the inner peripheral surface of the outer wall portion. Good.
(4) In the case of the metal plate with screw holes according to (3) above, the tip of the inner wall portion and the other surface of the metal plate may be flush with each other.

(5) Another aspect of the present invention is a metal plate having a screw hole, wherein the screw hole rises from one surface of the metal plate, and the edge of the inner wall portion A metal plate with a screw hole, including a cylindrical outer wall portion folded back to the outside of the inner wall portion, and having an internal thread formed on the inner peripheral surface of the inner wall portion.

(6) According to still another aspect of the present invention, a metal plate having a screw hole, a member having a through hole, and the metal plate and the through hole screwed into the screw hole in a state of being inserted into the through hole. And a metal plate with a screw hole according to any one of (1) to (5) above.

(7) Still another embodiment of the present invention is a method for producing a metal plate with a threaded hole according to any one of (1) to (4) above, wherein the outer wall portion and an inner side of the outer wall portion are provided. Forming a disk part continuous with the metal plate, forming a pilot hole in the center of the disk part, and bending the disk part with the pilot hole inside the outer wall part. Forming the inner wall portion, and processing the female thread on the inner peripheral surface of the molded inner wall portion.
(8) In the manufacturing method of the metal plate with a screw hole according to (7) above, in the step of forming the outer wall portion and the disc portion on the metal plate having a thickness dimension t (mm), the following formula (a) A punch having a shoulder size with a radius R (mm) satisfying the above may be used.
0.5 ≦ R / t ≦ 1.0 (a) Formula (9) In the method of manufacturing a metal plate with screw holes according to (7), the pilot hole is formed on the metal plate having a thickness dimension t (mm). In the drilling step, the pilot hole may be formed so that a radius r (mm) of the pilot hole satisfies the following formula (b).
0.5 ≦ r / t ≦ 1.2 (b) Formula (10) In the method for manufacturing a metal plate with screw holes according to (7), the outer wall portion and the metal plate having a thickness dimension t (mm) are provided. In the step of forming the disc portion, using a punch having a shoulder size of radius R (mm) satisfying the following formula (a), the step of drilling the pilot hole in the metal plate, the radius r ( mm) may be formed so that the following formula (b) is satisfied.
0.5 ≦ R / t ≦ 1.0 (a) Formula 0.5 ≦ r / t ≦ 1.2 (b) Formula

(11) Still another embodiment of the present invention is a method for manufacturing a metal plate with a threaded hole according to any one of the above (1) to (4), wherein a pilot hole is formed in the metal plate. Forming the outer wall part and a disk part continuous to the inside of the outer wall part concentrically with the pilot hole, and forming the inner wall part by bending the disk part to the inside of the outer wall part. And a step of processing the female screw on the inner peripheral surface of the inner wall portion.
(12) In the method of manufacturing a metal plate with a screw hole according to (11) above, in the step of forming the outer wall portion and the disc portion on the metal plate having a thickness dimension t (mm), the following equation (a) A punch having a shoulder size with a radius R (mm) satisfying the above may be used.
0.5 ≦ R / t ≦ 1.0 (a) Formula (13) In the method of manufacturing a metal plate with screw holes according to (11), the pilot hole is formed on the metal plate having a thickness dimension t (mm). In the drilling step, the pilot hole may be formed so that a radius r (mm) of the pilot hole after the step of forming the disc portion satisfies the following formula (b).
0.5 ≦ r / t ≦ 1.2 (b) Formula (14) In the method for manufacturing a metal plate with screw holes according to (11), the outer wall portion and the metal plate having a thickness dimension t (mm) are provided. In the step of forming the disc portion, the disc portion is formed in the step of drilling the pilot hole in the metal plate using a punch having a shoulder size with a radius R (mm) satisfying the following expression (a). You may make it open the said pilot hole so that the radius r (mm) of the said pilot hole after a step may satisfy the following Formula (b).
0.5 ≦ R / t ≦ 1.0 (a) Formula 0.5 ≦ r / t ≦ 1.2 (b) Formula

The metal plate with a threaded hole according to one aspect of the present invention described in the above (1) to (4) has a double wall structure having an outer wall portion and an inner wall portion folded inward from the outer wall portion. ing. According to this configuration, when the male screw is screwed into the female screw of the inner wall portion, the inner wall portion is subjected to the pressing force of the male screw and tends to be spread outward in the radial direction, but is supported by the outer wall portion around it. Therefore, excessive deformation of the inner wall portion is restricted. As a result, it is possible to prevent a screw hole from being damaged and a decrease in fastening force due to excessive expansion of the inner wall.
Further in terms of fastening force, the inner wall portion is always in a state of being given elastic force in the direction of diameter reduction due to the springback effect that occurs when the inner wall portion is folded back inside the outer wall portion. As a result, when the male screw is screwed into the female screw of the inner wall portion, the female screw is always pressed against the male screw and comes into close contact with each other, so that a high fastening force without loosening can be secured.
From the viewpoint of preventing breakage, since the conventional female screw is not formed on the outer wall portion, it is possible to prevent the root portion of the outer wall portion from being further thinned and easily damaged by the female screw formation. Moreover, although the internal thread is formed in the base part of an inner wall part, since the circumference | surroundings are comprised with the outer wall part, it has comprised the double wall structure, and is hard to be damaged. Thus, since high intensity | strength is ensured in each of the two bending parts of a screw hole, damage can be prevented.
As described above, according to the metal plate with a screw hole of this aspect, the screw hole is excellent in fastening force with the male screw and can be prevented from being damaged even if the plate thickness is reduced.

According to the metal plate with a screw hole according to the aspect described in (5) above, it has a double wall structure having an inner wall portion and an outer wall portion that is folded outward from the inner wall portion. According to this configuration, when the male screw is screwed into the female screw of the inner wall portion, the inner wall portion is subjected to the pressing force of the male screw and tends to be spread outward in the radial direction, but is supported by the outer wall portion around it. Therefore, excessive deformation of the inner wall portion is restricted. As a result, it is possible to prevent a screw hole from being damaged and a decrease in fastening force due to excessive expansion of the inner wall.

Since the housing according to the aspect described in (6) includes the above-described metal plate with a screw hole, the screw hole has excellent fastening force with a male screw and can prevent the screw hole from being damaged. Therefore, it is possible to prevent the screwed male screw from loosening.

The method for manufacturing a metal plate with a screw hole according to the embodiments described in the above (7) to (14) can process a screw hole that has excellent fastening force and can prevent breakage as described above. In addition, increases in the number of processes and processing costs can be reduced.

It is a figure which shows typically the screw hole of the metal plate with a screw hole which concerns on 1st Embodiment of this invention, Comprising: It is a longitudinal cross-sectional view at the time of seeing in the cross section containing the central axis of a screw hole. It is an enlarged view of the A section of FIG. 1, and is a figure before screwing in the tapping screw. FIG. 2 is an enlarged view of a portion A in FIG. 1, after a tapping screw is screwed in. It is a disassembled perspective view which shows the housing | casing which concerns on the same embodiment. It is a figure explaining the manufacturing method of the metal plate with a screw hole concerning the embodiment, Comprising: It is sectional drawing which shows the outer wall part shaping | molding step in a processing flow. It is sectional drawing which shows the drilling step following the outer wall part shaping | molding step of the same processing flow. It is sectional drawing which shows the inner wall part formation step following the drilling step of the same processing flow. It is sectional drawing which shows the internal thread formation step following the inner wall part formation step of the same processing flow. It is a figure explaining the modification of the manufacturing method of the metal plate with a screw hole concerning the embodiment, Comprising: It is sectional drawing which shows the drilling step in a processing flow. It is sectional drawing which shows the outer wall part shaping | molding step following the drilling step of the processing flow in the modification. It is sectional drawing which shows the inner wall part shaping | molding step following the outer wall part shaping | molding step of the processing flow in the modification. It is sectional drawing which shows the internal thread formation step following the inner wall part shaping | molding step of the processing flow in the modification. It is a figure which shows typically the screw hole of the metal plate with a screw hole which concerns on 2nd Embodiment of this invention, Comprising: It is a longitudinal cross-sectional view at the time of seeing in the cross section containing the center axis line of a screw hole. It is a figure which shows typically the screw hole of the metal plate with a screw hole which concerns on 3rd Embodiment of this invention, Comprising: It is a longitudinal cross-sectional view at the time of seeing in the cross section containing the center axis line of a screw hole. It is a figure which shows typically the screw hole of the metal plate with a screw hole which concerns on 4th Embodiment of this invention, Comprising: It is a longitudinal cross-sectional view at the time of seeing in the cross section containing the center axis line of a screw hole. It is a graph which shows the relationship between the rotation angle of a male screw, and the tightening torque in the test which evaluates the fastening force of a screw hole, and the relationship between the rotation angle of a male screw, and the change rate of a tightening torque. It is sectional drawing which shows typically the screw hole of the conventional metal plate with a screw hole. It is a figure explaining an example of the processing flow of the screw hole of the conventional metal plate with a screw hole, Comprising: It is sectional drawing which shows the drilling step in the same processing flow. It is sectional drawing which shows the burring step following the drilling step of the same processing flow.

Hereinafter, embodiments of a metal plate with a screw hole of the present invention, a housing including the metal plate with a screw hole, and a manufacturing method of the metal plate with a screw hole will be described with reference to the drawings. In addition, the metal plate with a screw hole of this invention is applicable to both a steel plate without plating and a plated steel plate.

[First Embodiment]
FIG. 1 is a diagram schematically showing a screw hole of a metal plate 10 with a screw hole according to the present embodiment, and is a longitudinal sectional view when seen in a cross section including a central axis CL of the screw hole. In addition, in order to make an understanding of a structure easy in FIG. 1, in addition to the metal plate 10 with a screw hole, the metal plate 51 which has the external thread 50 and the through-hole 51a is also shown with the imaginary line.
As shown in FIG. 1, the screw hole 12 included in the metal plate 10 with a screw hole of the present embodiment (hereinafter also simply referred to as the metal plate 10) includes an outer wall portion 12a and an inner wall portion 12b. The outer wall portion 12 a has a cylindrical shape that rises substantially vertically from the main body 10 a of the metal plate 10. In other words, in the cylindrical outer wall portion 12a, the base portion 12a1 that is one end in the axial direction is continuous with the main body 10a, and the central axis CL thereof is perpendicular to the surface 10x of the main body 10a. The other end 12a2 of the outer wall portion 12a in the direction along the central axis CL is continuous with the root portion 12c of the inner wall portion 12b. The inner wall portion 12b has a cylindrical shape arranged coaxially with the outer wall portion 12a, and is formed by being folded inward from the upper end (the other end 12a2) of the outer wall portion 12a. And the internal thread 12b1 is formed in the internal peripheral surface of the inner wall part 12b.

The screw hole 12 of the metal plate 10 with the screw hole of the present embodiment can reduce the thinning at the root portion 12c of the inner wall portion 12b and improve the fastening force of the screw hole 12 even when the plate thickness t is reduced. At the same time, breakage of the screw hole 12 can be prevented. The reason why the metal plate 10 with the screw hole of the present embodiment can suppress the thinning of the root portion 12c of the inner wall portion 12b will be described later. Here, “the root portion 12c of the inner wall portion 12b” means a portion that is continuous with the other end 12a2 of the outer wall portion 12a as shown by being surrounded by a one-dot chain line in FIG.

The screw hole 12 included in the metal plate 10 with the screw hole of the present embodiment has a double wall structure including an outer wall portion 12a and an inner wall portion 12b formed by folding back the outer wall portion 12a. Thus, even when the inner wall portion 12b receives a force in the diameter increasing direction by pressing from the male screw 50 during the screwing operation or loosening operation of the male screw 50, the inner wall portion 12b is supported from the periphery by the outer wall portion 12a. It is possible to prevent excessive deformation in the diameter expansion direction, and it is possible to prevent the fastening force from being lowered and the screw hole 12 from being damaged.

The screw hole 12 included in the metal plate 10 with the screw hole according to the present embodiment is formed so that the outer peripheral surface of the inner wall portion 12b is in contact with the inner peripheral surface of the outer wall portion 12a at the time of bending as described in the manufacturing method described later. However, the molded inner wall 12b is slightly deformed in the direction of diameter reduction by the spring back. Therefore, in a state where the male screw 50 is not screwed into the female screw 12b1 of the screw hole 12, the outer peripheral surface of the inner wall portion 12b is separated from the inner peripheral surface of the outer wall portion 12a, and the male screw 50 is screwed into the female screw 12b1 of the screw hole 12. In this state, at least a part of the outer peripheral surface of the inner wall portion 12b is in contact with the inner peripheral surface of the outer wall portion 12a. This configuration will be described in more detail with reference to FIGS.

First, as shown in FIG. 2, in a state before the male screw 50 is screwed into the screw hole 12, the tip 12b3 of the inner wall portion 12b is caused to be the root portion of the outer wall portion 12a by the spring back generated after the screw hole 12 is formed by bending. It is slightly separated from 12a1. Therefore, a slight gap is formed between the outer peripheral surface of the inner wall portion 12b and the inner peripheral surface of the outer wall portion 12a.
Subsequently, as shown in FIG. 3, in the state where the male screw 50 is screwed into the screw hole 12, the inner wall portion 12 b that has received the pressing force by the male screw 50 is elastically deformed in the diameter increasing direction according to the amount of spring back, As a result, the outer peripheral surface of the inner wall portion 12b abuts on the inner peripheral surface of the outer wall portion 12a, and the gap is eliminated. Therefore, as described above, the deformation of the inner wall portion 12b is received and regulated by the outer wall portion 12a. In addition, the inner wall portion 12b exhibits a restoring force to return to the state of FIG. Due to this restoring force, the inner wall portion 12b is urged toward the male screw 50 as shown by an arrow X in FIG. 3, so that the female screw 12b1 and the male screw 50 are kept in close contact with each other. Therefore, the fastening force between the screw hole 12 and the male screw 50 can be further increased to prevent the male screw 50 from loosening.

As described above, the screw holed metal plate 10 of the present embodiment includes the cylindrical outer wall portion 12a in which the screw hole 12 rises perpendicularly from one surface 10x of the metal plate 10 and the upper end edge of the outer wall portion 12a. A cylindrical inner wall portion 12b folded inside the outer wall portion 12a, and an internal thread 12b1 is formed on the inner peripheral surface of the inner wall portion 12b.
According to this configuration, even if the thickness t of the metal plate 10 with a screw hole is reduced, the screw hole 12 is excellent in fastening force with the male screw 50 and can be prevented from being damaged. In addition, since the screw hole 12 is a single piece formed by molding, it does not require labor such as welding, and the processing cost does not increase significantly.

Moreover, in the metal plate 10 with a screw hole of this embodiment, the front-end | tip 12b3 of the inner wall part 12b and the other surface 10y of a metal plate are flush | level.
According to this configuration, for example, when flatness without unevenness is required on the entire surface of the other surface 10y that is the mounting surface of the metal plate 10 with screw holes, the degree of unevenness due to the formation of the screw holes 12 is minimized. It is possible to limit the length of the female screw 12b1 to the maximum. Therefore, the metal plate 10 with a screw hole which has both aesthetics and fastening force can be obtained.

Subsequently, the housing according to the present embodiment will be described below with reference to FIGS. 1 and 4.
As shown in FIG. 4, the housing 70 according to the present embodiment includes the above-described metal plate 10 with screw holes, a member (metal plate) 51 having a through hole 51a, and a screw hole inserted in the through hole 51a. 12 and a male screw 50 that joins between the screw-holed metal plate 10 and the member 51. 4 is an exploded perspective view, but a cross-sectional view of the main part of the screw hole 12 in a state where the metal plate 10 with the screw hole and the member 51 are joined by screwing the male screw 50 into the screw hole 12 is shown in FIG. It is as shown in.
According to the housing 70 of this embodiment, since the metal plate 10 with a screw hole has the above-described structure, the fastening force between the screw hole 12 and the male screw 50 is excellent, and the screw hole 12 can be prevented from being damaged. It has become. Moreover, it is the housing | casing 70 which can also prevent that the screwed male screw 50 loosens. Examples of the casing 70 include an indoor unit and an outdoor unit of an air conditioner, and a casing of a substation facility.

In FIG. 1, the member 51, which is a metal plate having a through-hole 51a, is attached to the tip 12b3 side of the inner wall portion 12b. However, the present invention is not limited to this configuration. A mounting configuration can also be adopted. That is, in FIG. 1, the vertical arrangement relationship between the metal plate 10 with the screw holes and the member 51 may be reversed. The “tip 12b3 of the inner wall portion 12b” means an end located opposite to the root portion 12c in the direction along the central axis CL. In addition, the member 51 is not limited to a metal plate, and includes an accessory having a through hole.

Then, the manufacturing method of the metal plate 10 with a screw hole of this embodiment is demonstrated. In the present embodiment, the hole making step is performed after the outer wall portion forming step, but a modified example (described later) in which the outer wall portion forming step is performed after the hole making step can also be employed.

5A to 5D are schematic diagrams showing a processing flow of the metal plate manufacturing method of the present embodiment, in which FIG. 5A is an outer wall forming step, FIG. 5B is a drilling step, FIG. 5C is an inner wall forming step, and FIG. Indicates the female thread forming step.
First, in the outer wall portion forming step, the outer wall portion 20a and the disc portion 20b connected to the outer wall portion 20a are formed on the metal plate 20 (material) to be processed. The cylindrical outer wall portion 20 a rises from the metal plate 20 such that one end in the direction of the central axis CL is continuous with the main body of the metal plate 20 and the central axis CL is perpendicular to the surface of the metal plate 20. The inner side of the other end in the direction of the central axis CL of the outer wall portion 20a is continuous with the disc portion 20b.

The outer wall portion 20a and the disc portion 20b having such a shape can be formed by overhanging or drawing using a punch and a die. In the case of overhanging, as shown in FIG. 5A, in addition to the overhanging punch 35 and the overhanging die 36, a blank holder 36a is further used. With the metal plate 20 held between the front and back surfaces of the blank holder 36 a and the die 36, the punch 35, the die 36 and the blank holder 36 a are moved relative to each other, and a part of the metal plate 20 is moved together with the punch 35. Push into the die 36. Thereby, the cylindrical outer wall portion 20a and the disc portion 20b are formed on the metal plate 20.

In the subsequent drilling step, a pilot hole is drilled in the center of the disc portion 20b. That is, as shown in FIG. 5B, the pilot hole 20b1 is formed in the disc portion 20b by performing drilling by shearing using the punch 31 for punching and the die 32 for drilling. Drilling can also be performed by cutting using a drill or drilling with a laser cutting machine.

In the subsequent inner wall portion forming step, the inner wall portion 12b is formed by folding the disk portion 20b having the prepared hole 20b1 and folding it inside the outer wall portion 20a (12a). The disk portion 20b can be bent by a so-called hole expanding process.

That is, the hole expanding process can be performed using a hole expanding punch 37, a hole expanding die 38 and a blank holder 39 as shown in FIG. 5C. That is, with the die 38 and the blank holder 39 sandwiching the metal plate 20 from the front and back surfaces, the punch 37 and the die 38 and the blank holder 39 are relatively moved. At that time, the punch 37 is pressed into the pilot hole 20b1. Thus, when the disc portion 20b of the metal plate 20 is pushed into the outer wall portion 20a together with the punch 37, the disc portion 20b is expanded in the radial direction while being stretched in the pushing direction of the punch 37. An inner wall portion 12b (20b) that is cylindrical and is folded inward from the outer wall portion 12a (20a) is formed. At this time, the outer peripheral surface of the inner wall portion 12b is formed so as to be in contact with the inner peripheral surface of the outer wall portion 12a. However, since the inner wall portion 12b is slightly deformed in the diameter reducing direction by the spring back, as shown in FIG. A gap occurs.

In the subsequent thread cutting step, the internal thread 12b1 is processed on the inner peripheral surface of the formed inner wall 12b. There is no restriction | limiting in particular in the processing method of the internal thread 12b1, For example, as shown to FIG. 5D, the internal thread 12b1 can be processed with the tap 40. FIG. As described above, according to the manufacturing method of the present embodiment, the metal plate 10 with a screw hole, that is, the screw hole 12 including the outer wall portion 12a and the inner wall portion 12b obtained by folding back a part of the outer wall portion 12a, The plate 20 can be processed.

According to the manufacturing method of the present embodiment, it is possible to reduce the thinning at the root portion of the screw hole as compared with the conventional method of forming the screw hole using burring as described with reference to FIG. That is, in the conventional manufacturing method, as shown in FIG. 12B, in the state of holding the metal plate 520 between the die 534 and the blank holder 539 during the burring process, together with the punch 533, the peripheral portion of the metal plate 520 Is pushed into the recess of the die 534 and deformed to form the vertical wall portion 511. At that time, in the metal plate 520, the base portion 511 a around the deformed pilot hole and the portion sandwiched between the die 534 and the blank holder 539 are close to each other, so that the base portion of the vertical wall portion 511 is very large. Tensile stress is generated and, as a result, thinning is promoted.

On the other hand, in the present embodiment, as shown in FIG. 5C, the circular plate portion 20b and the outer wall portion 20a (12a) together with the punch 37 are sandwiched between the die 38 and the blank holder 39 in the inner wall portion forming step. The inner wall portion 12b is formed by being pushed and deformed inside. At that time, the outer wall portion 12 a is interposed between the deformed disc portion 20 b and the portion sandwiched between the die 38 and the blank holder 39 in the metal plate 20. Thereby, the tensile stress which arises in the root part 12c of the inner wall part 12b is relieve | moderated, As a result, the thinning amount in the root part 12c can be reduced rather than the said conventional root part 511a (refer FIG. 11).

Therefore, according to the manufacturing method of the present embodiment, the fastening force between the formed screw hole 12 and the male screw 50 can be improved, and damage to the screw hole 12 can be prevented. Further, since the screw hole 12 has a double wall structure of the outer wall portion 12a and the inner wall portion 12b, the inner wall portion 12b can be prevented from being deformed in the diameter increasing direction, and the fastening force is reduced by deformation and the screw hole 12 Damage can be prevented. Further, since the disk portion 20 b is bent to form the inner wall portion 12 b, when the male screw 50 is screwed into the screw hole 12, a restoring force is generated by the spring back of the inner wall portion 12 b, and the inner wall portion 12 b comes into close contact with the male screw 50. As a result, the fastening force of the screw hole 12 is further improved, and the screwed male screw 50 can be more reliably prevented from loosening.

In the present embodiment, the screw hole 12 can be formed by four steps of outer wall forming, drilling, inner wall forming, and female screw forming. Therefore, compared with the conventional screw hole proposed in Patent Document 1 described above, Increase in processing man-hours can be reduced. In the above four steps, high machining accuracy is not required. Therefore, according to the manufacturing method of the present embodiment, an increase in processing cost can be reduced as compared with the screw hole proposed in Patent Document 1 described above.

As a method of manufacturing the metal plate with screw holes of the present invention, for example, the modifications shown in FIGS. 6A to 6D can be adopted as forms other than the above description.
6A shows a drilling step, FIG. 6B shows an outer wall forming step, FIG. 6C shows an inner wall forming step, and FIG. 6D shows an internal thread forming step. In this modification, when the screw hole 12 is formed, a pilot hole is first drilled in the drilling step. That is, as shown in FIG. 6A, drilling is performed by shearing using a punch 31 for punching and a die 32 for drilling, and a pilot hole 20b1 is made in the metal plate 20 to be processed. Drilling can also be performed by cutting using a drill or drilling with a laser cutting machine.

In the subsequent outer wall portion forming step, as shown in FIG. 6B, a cylindrical outer wall portion 20a and a disc portion 20b continuous with the outer wall portion 20a are formed on the metal plate 20. The cylindrical outer wall portion 20 a rises from the metal plate 20 so that the base portion, which is one end in the axial direction, is continuous with the metal plate 20 and the center axis CL is perpendicular to the surface of the metal plate 20. Moreover, the inner side of the other end of the outer wall part 20a in the direction along the center axis line CL is continuous with the disk part 20b. In this modification, the outer wall portion 20a and the disc portion 20b are formed such that the pilot hole 20b1 and the cylindrical outer wall portion 20a are concentric.

The outer wall portion 20a and the disk portion 20b can be formed by overhanging or drawing using a punch and a die. In the case of the overhanging process, a blank holder 36a is used in addition to the overhanging punch 35 and the overhanging die 36 shown in FIG. 6B. The metal plate 20 is disposed so that the center of the pilot hole 20b1 coincides with the center of the recess of the die 36, and the metal plate 20 is sandwiched between the die 36 and the blank holder 36a. In this state, the punch 35, the die 36, and the blank holder 36a are relatively moved, and a part of the metal plate 20 is pushed into the die 36 together with the punch 35. Thereby, the cylindrical outer wall portion 20a and the disc portion 20b are formed on the metal plate 20. At that time, the pilot hole 20b1 is deformed and expanded in diameter.

In the subsequent inner wall portion forming step, as shown in FIG. 6C, the inner disk portion 12b is formed by folding the formed disc portion 20b inward from the outer wall portion 12a.
In the subsequent female screw forming step, as shown in FIG. 6D, the female screw 12b1 is processed on the inner peripheral surface of the inner wall portion 12b. The bending of the disc portion 20b can be performed by hole expansion processing as in the above-described embodiment. Further, the processing of the female screw 12b1 is not particularly limited as in the above-described embodiment, and can be processed by the tap 40, for example.

The screw hole 12 provided with the outer wall portion 12a and the inner wall portion 12b can be formed in the metal plate 20 also by the manufacturing method of the above modification. Also in this modified example, when the disk part 20b is bent in the inner wall part forming step, between the disk part 20b to be deformed and the part sandwiched between the die 38 and the blank holder 39 in the metal plate 20. The outer wall 12a is interposed. For this reason, the thickness reduction of the root portion 12c of the inner wall portion 12b can be reduced. As a result, the fastening force of the screw hole 12 can be improved and the screw hole 12 can be prevented from being damaged.

Also in the present modification, as in the above-described embodiment, the obtained screw hole 12 has a double wall structure having the outer wall portion 12a and the inner wall portion 12b. Therefore, the inner wall portion 12b is excessively increased in the diameter increasing direction. It is possible to prevent the deformation, thereby preventing the fastening force from being lowered and the screw hole 12 from being damaged. Further, when the male screw 50 is screwed into the screw hole 12, the inner wall portion 12b is brought into close contact with the male screw 50 by the spring back. Thereby, the fastening force of the screw hole 12 can be further improved, and the screwed male screw 50 can be prevented from loosening.

In this modification, since the screw hole 12 can be formed by four steps of drilling, outer wall forming, inner wall forming, and female screw forming, the number of processing is increased compared to the conventional screw hole proposed in Patent Document 1 described above. Can be suppressed. In addition, high processing accuracy is not required for the above four steps. Therefore, this modification can reduce an increase in processing cost as compared with the screw hole proposed in Patent Document 1 described above.

In this modification, the steps of forming the outer wall portion and the inner wall portion can be performed with the same apparatus, and in this case, the increase in the number of processing can be further suppressed. Specifically, in FIG. 6B, the hole expanding punch 37 (not shown) shown in FIG. 6C is arranged so as to face the overhanging punch 35. Thus, after forming the outer wall portion 20a (12a) and the disc portion 20b with the overhanging punch 35 and the overhanging die 36, the inner wall portion 12b can be immediately formed with the hole expanding punch 37.

In both the first embodiment described above and the modifications thereof, when forming the outer wall portion 20a (12a) and the disc portion 20b in the outer wall portion forming step (see FIGS. 5A and 6B), the die 36 and the shoulder It is preferable to use a punch 35 whose radius R (mm) satisfies the following expression (1). Also, in the drilling step (see FIGS. 5B and 6A), the pilot hole is drilled so that the radius r (mm) of the pilot hole before the inner wall portion molding in the subsequent inner wall portion molding step satisfies the following expression (2). Is preferred. Here, t represents the thickness (mm) of the metal plate 20.
0.5 ≦ R / t ≦ 1.0 (1) Formula 0.5 ≦ r / t ≦ 1.2 (2) Formula

Here, the “shoulder radius” of the punch 35 refers to the outer peripheral surface of the punch 35 that contacts the outer wall portion 20a (12a) formed on the metal plate 20 and the punch 35 that contacts the formed disk portion 20b. This means the radius of the R portion connecting the tip surface (see FIGS. 5A and 6B). In addition, the “radius of the pilot hole before the inner wall part molding in the inner wall part molding step” specifically corresponds to the radius of the pilot hole 20b1 drilled in the drilling step shown in FIG. 5B in the above embodiment, In the modified example, the radius of the prepared hole 20b1 in the state of being deformed in the diameter increasing direction in the outer wall portion forming step shown in FIG. 6B after the drilling step is applicable.

If the shoulder radius R (mm) of the punch 35 is smaller than 0.5 × t (mm) in the outer wall forming step, the punch 35 connects the outer wall portion 20a (12a) and the disc portion 20b to the R portion (curved portion). ), And this part may be thinned and lead to breakage, resulting in a product failure, and the production yield is reduced. On the other hand, when the radius R (mm) of the shoulder of the punch 35 is larger than 1.0 × t (mm), an R portion (curved portion) connecting the outer wall portion 20a (12a) and the disc portion 20b in the inner wall portion forming step. As a result, the outer wall portion 20a (12a) falls to the inner wall portion 12b side, and as a result, the product may be defective.

If the radius r (mm) of the pilot hole 20b1 is smaller than 0.5 × t (mm), it is necessary to deform the peripheral part of the pilot hole 20b1 when the disk part 20b is bent in the inner wall part forming step. Power is excessive. Thereby, the R portion (curved portion) connecting the outer wall portion 20a (12a) and the main body of the metal plate 20 is deformed, and as a result, the inner wall portion 12b and the outer wall portion 20a (12a) cannot be formed, resulting in a product defect. There is a decrease in manufacturing yield. On the other hand, when the radius r (mm) of the pilot hole is larger than 1.2 × t (mm), the inner wall portion 12b formed by the inner wall portion forming step has a small height and a small number of threads. For this reason, there exists a possibility that sufficient fastening force with the external thread 50 cannot be obtained.

There is no particular limitation on the material of the metal plate itself in the manufacturing method of the metal plate with a screw hole, the housing having the same, and the metal plate with a screw hole of the present invention.

In the manufacturing method of the metal plate with screw holes of the present invention, it is preferable to use the punch 37 having a tapered portion at the tip as shown in FIGS. 5C and 6C in the inner wall forming step. The reason for this is that if a punch 37 provided with a tapered portion whose outer diameter decreases as it approaches the tip as compared with the straight-shaped burring punch 533 shown in FIG. This is because it is easy to promote bending deformation at the R portion (bending portion) connecting the outer wall portion 20a (12a) and the disc portion 20b, and the falling of the outer wall portion 20a (12a) can be suppressed.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. In the description, the difference from the first embodiment will be mainly described, and the rest will be omitted because it is the same as the first embodiment.
FIG. 7 is a diagram schematically illustrating the screw hole 12 of the metal plate 100 with the screw hole according to the present embodiment, and corresponds to FIG. 3 when viewed in a cross section including the central axis CL of the screw hole 12. It is a longitudinal cross-sectional view.

As for the metal plate 100 with a screw hole of this embodiment, the length dimension L1 of the inner wall part 12b is longer than the thing of the said 1st Embodiment. As a result, the front end 12b3 of the inner wall portion 12b protrudes from the other surface 10y of the metal plate.
According to this configuration, for example, when the metal plate 100 with a screw hole and another metal plate 51 are overlapped and aligned, as shown in FIG. 7, the protruding portion of the inner wall portion 12 b is replaced with the other metal plate 51. By being fitted into the through hole 51a, the alignment can be easily performed.
Further, since the length dimension of the female screw 12b1 can be made longer than that of the first embodiment, the length of the portion screwed with the male screw 50 can be made longer and fastening can be performed more reliably.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. In the description, the difference from the first embodiment will be mainly described, and the rest will be omitted because it is the same as the first embodiment.
FIG. 8 is a diagram schematically showing the screw hole 12 of the metal plate 110 with the screw hole according to the present embodiment, and corresponds to FIG. 3 when viewed in a cross section including the central axis CL of the screw hole 12. It is a longitudinal cross-sectional view.

As for the metal plate 10 with a screw hole of this embodiment, the length dimension L2 of the inner wall part 12b is shorter than the thing of the said 1st Embodiment. As a result, the front end 12b3 of the inner wall portion 12b is at a position deeper than the other surface 10y of the metal plate. Therefore, when screwing, a slight gap is generated between the surfaces of the other metal plates 51.
According to this configuration, for example, when the metal plate 10 with screw holes and the other metal plate 51 are overlapped and then screwed with the male screw 50, the inner wall portion 12b is shorter than in the case of the first embodiment. The length of the portion screwed with the male screw 50 is shortened. However, since there is the gap, when the male screw 50 is tightened, the inner wall portion 12b is allowed to have its tip 12b3 approaching the screw head of the male screw 50. Then, when the male screw 50 is tightened, the male screw 50 tries to draw the inner wall portion 12b toward itself, and as a result, the cylindrical inner wall portion 12b attempts to reduce the diameter. As a result, the inner wall portion 12b is more closely attached to the male screw 50, and a high fastening force can be ensured.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. In the description, the difference from the first embodiment will be mainly described, and the rest will be omitted because it is the same as the first embodiment.
FIG. 9 is a diagram schematically showing the screw hole 212 of the metal plate 200 with a screw hole according to the present embodiment, and corresponds to FIG. 3 when viewed in a cross section including the central axis CL of the screw hole 212. It is a longitudinal cross-sectional view.

The metal plate 200 with a screw hole of the present embodiment is a metal plate having a screw hole 212, and the screw hole 212 rises from one surface of the metal plate 220, and an end of the inner wall portion 212b. A cylindrical outer wall portion 212a folded from the edge to the outside of the inner wall portion 212b is provided, and a female screw 212b1 is formed on the inner peripheral surface of the inner wall portion 212b.
In this configuration, unlike the first embodiment, the effect of the spring back by the inner wall portion 212b is not obtained, but the deformation of the inner wall portion 212b in the diameter increasing direction when the male screw (not shown) is tightened is prevented. It can be received by the part 212a. Therefore, excessive deformation of the inner wall portion 212b can be restricted, so that the screw hole 212 can be prevented from being damaged or the fastening force can be reduced even if the thickness of the metal plate 220 is reduced.
In addition, the metal plate 200 with a screw hole of this embodiment can also be used as a component of a housing | casing. That is, a metal plate having a screw hole, a member having a through hole, a male screw that is screwed into the screw hole in a state of being inserted into the through hole, and couples the metal plate and the member having the through hole, The metal plate 200 with a screw hole can be used as the metal plate.

In order to verify the effect of the present invention, a screw hole was formed in the metal plate by the method for manufacturing a metal plate with a screw hole of the present invention, and a test for evaluating the fastening force of the screw hole was performed.

As a test material, a steel plate having a thickness of 0.4 to 0.6 mm and a tensile strength of 270 MPa was used. In these steel plates, screw holes with a nominal diameter of M3 in JIS B0205 (2001) were machined by the method for manufacturing a metal plate with screw holes according to the first embodiment described with reference to FIGS. 5A to 5D.

The outer wall portion forming step is performed by an overhanging process, and uses an overhanging punch 35 having an outer diameter of 3.2 mm, a die 36 having a concave portion having an inner diameter of 4.6 mm, and a blank holder 36a. Part 20a was molded. At that time, the shoulder radius R of the overhanging punch 35 was changed. Further, the drilling step was performed by a shearing process using the drilling punch 31 and the drilling die 32, and the radius r of the pilot hole 20b1 was changed at that time. The inner wall portion forming step was performed using a hole expanding punch 37 having a tapered tip, a hole expanding die 38 and a blank holder 39. The hole expanding punch 37 has a straight portion with a radius of 1.2 mm, a corner portion of the tapered portion having a chamfer of 60 ° with respect to the central axis CL, and a radius of the distal end of the tapered portion of 1.4 mm. I used something.

For comparison, a metal plate 10 with a screw hole in which a screw hole by a conventional burring process is formed on a metal plate was also manufactured by the processing flow described with reference to FIGS. 12A and 12B (Test Nos. 1-1A, 2- 1A, 3-1A).
For comparison, a metal plate with a screw hole (not shown) having the structure shown in FIG. 1 of Patent Document 2 cited in the background art was also manufactured (Test Nos. 1-1B, 2-1B, 3). -1B). If this comparative example is described with reference to FIG. 1 shown in the first embodiment, even when the male screw 50 is screwed in, the inner peripheral surface of the outer wall portion 12a and the outer peripheral surface of the inner wall portion 12b are separated and have a large gap. This is a structure in which the periphery of the inner wall portion 12b is not supported by the outer wall portion 12a.

In each test, 20 metal plates were prepared and screw holes were machined. At that time, the number of processing defects was investigated and the production yield was calculated.

Also, a test for evaluating the fastening force was performed on the screw holes of each metal plate with screw holes. In the test for evaluating the fastening force of the screw hole, the male screw was screwed into the screw hole of the metal plate using a screw fastening device capable of measuring the tightening torque. At that time, the relationship between the rotation angle of the male screw and the tightening torque was measured. Differentiating the relationship between the rotation angle (°) of the obtained male screw and the tightening torque (N · m) with respect to the rotation angle, the rate of change of the rotation angle (°) of the male screw and the tightening torque (N · m / °) Sought a relationship with.

FIG. 10 is a schematic diagram showing the relationship between the rotation angle of the male screw and the tightening torque and the relationship between the rotation angle of the male screw and the change rate of the tightening torque in the test for evaluating the fastening force of the screw hole. As shown in the figure, when the rotation angle increases as the male screw is screwed in, the tightening torque starts to increase from a constant state at approximately 0 (zero) in the initial stage, then becomes substantially constant again, and then decreases. To do. From such a relationship between the rotation angle and the tightening torque, a point O at which the tightening torque is 0 and the state is increased from a constant state was obtained.

On the other hand, when the rotation angle increases as the male screw is screwed in, the change rate of the tightening torque becomes substantially constant after starting to increase at the above point O, and then decreases. From the relationship between the rotation angle of the male screw and the change rate of the tightening torque, the rotation angle at which the change rate of the tightening torque turns from a constant state to a decrease was obtained. A point on the curve indicating the relationship between the rotation angle and the tightening torque at this rotation angle was defined as a point A. This point A represents the point at which the internal thread (screw hole) has started plastic deformation.

The straight line L connecting the points O and A thus obtained was drawn. Also, a straight line L ′ obtained by translating the straight line L by 10 ° in the direction in which the rotation angle increases is drawn. An intersection point of the straight line L ′ and a curve indicating the relationship between the rotation angle and the tightening torque was defined as a point B. As an index for evaluating the fastening force of the screw hole, the ratio (TB / TA, dimensionless) of the tightening torque (N · m) at point B to the tightening torque TA (N · m) at point A was calculated. Such TB / TA indicates a rate at which the fastening torque is maintained after the female screw starts plastic deformation, in other words, a rate at which the fastening force with the male screw in the screw hole is maintained after the female screw starts plastic deformation. . For this reason, the larger the TB / TA is, the more excellent the fastening force of the screw hole with the male screw.

The meanings of the symbols in the “Evaluation of fastening force” column in Tables 1 to 3 are as follows.
VG (Very Good): indicates that TB / TA ≧ 1.2 is satisfied.
GD (Good): Indicates that 1.2> TB / TA ≧ 1.0 is satisfied.
FA (Fair): Indicates that 1.0> TB / TA ≧ 0.8 is satisfied.
BD (Bad): Indicates that TB / TA <0.8 is satisfied.

Tables 1 to 3 show the test numbers in each test. , Thickness t of metal plate, processing method of screw hole, shoulder radius R of overhanging punch, R / t value, conformity with the above formula (1), radius of pilot hole before inner wall forming The values of r and r / t, whether or not the equation (2) is satisfied, the production yield, the value of the fastening force index TB / TA and its evaluation, and the test category are shown. Here, the conformity to the equation (1) indicates that the value of R / t satisfies the equation (1) in the case of “Y”, and the value of R / t is in the case of “N”. (1) Indicates that the expression is not satisfied. The conformity to the equation (2) indicates that the value of r / t satisfies the equation (2) when “Y”, and the value of r / t when the value is “N”. 2) Indicates that the expression is not satisfied.

From Tables 1 to 3, the fastening force was evaluated as BD in the comparative example, but as VG, GD, or FA in the example of the present invention. Therefore, the metal plate with a screw hole of this invention, the housing | casing which comprises it, and the manufacturing method of a metal plate have confirmed that the screw hole was excellent in the fastening force with a male screw.

Further, in the comparative examples (Test Nos. 1-1A, 2-1A, 3-1A), the base of the vertical wall portion is broken by thinning due to burring, or the thread of the screw hole cannot be sufficiently formed by threading. The number of occurrences increased as the thickness of the specimen became thinner. As a result, in the comparative example, the production yield was 70% or less. On the other hand, in the example of this invention, all became 90% or more, and the manufacturing yield could be improved.
Further, in the comparative examples (Test Nos. 1-1B, 2-1B, 3-1B), the internal thread portion corresponding to the inner wall portion is not supported by the peripheral portion corresponding to the outer wall portion, so the rigidity is low. For this reason, there are problems such that it is difficult to perform accurate tapping and the processing accuracy cannot be maintained, and the processing accuracy of the female screw is not uniform in the circumferential direction. Thus, if the rigidity of the internal thread processing portion corresponding to the inner wall is weak and the processing accuracy of the internal thread is low, the engagement between the internal thread and the external thread tends to be uneven in the circumferential direction of the internal thread.

Further, in the examples of the present invention, in the test where the R / t value was less than 0.5 and the test where the R / t value exceeded 1.0, both of the production yields were confirmed to be slightly decreased. . On the other hand, in the test where the value of r / t was less than 0.5, a slight decrease in production yield was confirmed. In addition, in the test where the r / t value is 1.2 or less, the fastening force is evaluated as VG or GD, whereas in the test where the r / t value exceeds 1.2, the fastening force is evaluated. It became FA. From these, it is possible to manufacture by using a punch that satisfies the expression (1) in the outer wall forming step and making a prepared hole so that the radius r of the prepared hole before forming the inner wall satisfies the expression (2). It was revealed that the yield and the fastening force of the screw holes can be further improved.

According to the metal plate with a screw hole, the housing provided with the metal plate with a screw hole, and the manufacturing method of the metal plate with a screw hole according to the present invention, the screw hole has excellent fastening force with a male screw even when it is thinned. Damage to screw holes can be prevented. Therefore, if the metal plate with a threaded hole of the present invention, the housing provided with the metal plate with a threaded hole, and the method for producing the metal plate with a threaded hole are applied to an outdoor unit of an air conditioner or a housing of a substation facility, This can greatly contribute to thinning.

10, 100, 110, 200: Metal plate with screw hole 10x: One surface of metal plate 10y: Other surface of metal plate 12: Screw hole 12a, 212a: Outer wall portion 12b, 212b: Inner wall portion 12b1, 212b1: Female screw 12b3: tip of inner wall portion 20b: disc portion 37: punch 50: male screw 51: member 51a: through hole 70: housing

Claims (14)

1. A metal plate having a screw hole,
   The screw hole includes a cylindrical outer wall portion that rises from one surface of the metal plate, and a cylindrical inner wall portion that is folded back from the edge of the outer wall portion to the inside of the outer wall portion,
   A metal plate with a screw hole, wherein an internal thread is formed on an inner peripheral surface of the inner wall portion.
2. The metal plate with a screw hole according to claim 1, wherein the tip of the inner wall portion and the other surface of the metal plate are flush with each other.
3. In a state where a male screw is not screwed into the female screw of the screw hole, the outer peripheral surface of the inner wall portion is separated from the inner peripheral surface of the outer wall portion,
   The at least one part of the said outer peripheral surface of the said inner wall part contact | abuts to the said inner peripheral surface of the said outer wall part in the state in which the said male screw is screwed together by the said female screw of the said screw hole, A metal plate with a screw hole according to 1.
4. The metal plate with a screw hole according to claim 3, wherein the tip of the inner wall portion and the other surface of the metal plate are flush with each other.
5. A metal plate having a screw hole,
   The screw hole includes a cylindrical inner wall portion that rises from one surface of the metal plate, and a cylindrical outer wall portion that is folded back from the edge of the inner wall portion to the outside of the inner wall portion,
   A metal plate with a screw hole, wherein an internal thread is formed on an inner peripheral surface of the inner wall portion.
6. A metal plate having a screw hole; a member having a through hole; and a male screw that is screwed into the screw hole while being inserted into the through hole to couple the metal plate and the member having the through hole. A housing that
   A casing, wherein the metal plate is a metal plate with a screw hole according to any one of claims 1 to 5.
7. A method for producing a metal plate with a screw hole according to any one of claims 1 to 4,
   Forming the outer wall portion and a disk portion continuous inside the outer wall portion into the metal plate;
   Drilling a pilot hole in the center of the disc part;
   Bending the disk portion with the prepared hole formed inside the outer wall portion to form the inner wall portion; and
   And a step of processing the female screw on the inner peripheral surface of the molded inner wall portion.
8. In the step of forming the outer wall portion and the disc portion on the metal plate having a thickness dimension t (mm), a punch having a shoulder dimension with a radius R (mm) satisfying the following expression (1) is used. The manufacturing method of the metal plate with a screw hole of Claim 7.
   0.5 ≦ R / t ≦ 1.0 (1) Formula
9. In the step of opening the pilot hole in the metal plate having a thickness dimension t (mm), the pilot hole is formed so that a radius r (mm) of the pilot hole satisfies the following formula (2). Item 8. A method for producing a metal plate with screw holes according to Item 7.
   0.5 ≦ r / t ≦ 1.2 Formula (2)
10. In the step of forming the outer wall portion and the disc portion on the metal plate having a thickness dimension t (mm), a punch having a shoulder dimension with a radius R (mm) satisfying the following expression (1) is used:
    The screw hole according to claim 7, wherein the pilot hole is formed so that a radius r (mm) of the pilot hole satisfies the following formula (2) in the step of drilling the pilot hole in the metal plate. A manufacturing method of a metal plate with a ring.
    0.5 ≦ R / t ≦ 1.0 (1) Formula 0.5 ≦ r / t ≦ 1.2 (2) Formula
11. A method for producing a metal plate with a screw hole according to any one of claims 1 to 4,
    A step of drilling a pilot hole in the metal plate;
    Concentrically with the pilot hole, forming the outer wall portion and a disk portion continuous inside the outer wall portion;
    Bending the disc part inside the outer wall part to form the inner wall part;
    Processing the female thread on the inner peripheral surface of the inner wall portion;
    The manufacturing method of the metal plate with a screw hole characterized by having.
12. In the step of forming the outer wall portion and the disc portion on the metal plate having a thickness dimension t (mm), a punch having a shoulder dimension with a radius R (mm) satisfying the following expression (1) is used. The manufacturing method of the metal plate with a screw hole of Claim 11.
    0.5 ≦ R / t ≦ 1.0 (1) Formula
13. In the step of drilling the pilot hole in the metal plate having a thickness dimension t (mm), the radius r (mm) of the pilot hole after the step of forming the disk portion satisfies the following formula (2): The method for producing a metal plate with screw holes according to claim 11, wherein a pilot hole is formed.
    0.5 ≦ r / t ≦ 1.2 Formula (2)
14. In the step of forming the outer wall portion and the disc portion on the metal plate having a thickness dimension t (mm), a punch having a shoulder dimension with a radius R (mm) satisfying the following expression (1) is used:
    In the step of drilling the pilot hole in the metal plate, the pilot hole is drilled so that a radius r (mm) of the pilot hole after the step of forming the disc portion satisfies the following formula (2). The manufacturing method of the metal plate with a screw hole of Claim 11.
    0.5 ≦ R / t ≦ 1.0 (1) Formula 0.5 ≦ r / t ≦ 1.2 (2) Formula

Images