JP7744249B2 - Component manufacturing method and weld nut - Google Patents

Description

This disclosure relates to a method for manufacturing a component and a weld nut.

A technique for welding a weld nut around a hole in a workpiece using projection welding is known. The weld nut in Patent Document 1 has a guide attached to the edge of the opening of the threaded hole, which is configured to fit into the hole in the workpiece. During projection welding, the guide determines the positioning, and projection welding is performed on the weld nut, which is positioned so that the guide fits into the hole.

The guide closes the gap between the workpiece's welding surface and the periphery of the opening of the threaded hole in the weld nut placed on the weld surface, preventing spatter from entering the threaded hole during projection welding. This reduces damage to the internal thread in the threaded hole caused by spatter, and as a result, the bolt can be securely fastened to the weld nut welded to the workpiece.

Japanese Patent Application Laid-Open No. 2006-283884

However, providing a guide for the weld nut, as in Patent Document 1, can make the work more difficult. Specifically, the weld nut needs to be positioned so that the guide fits into the hole, making it difficult to flexibly determine the position where the weld nut is welded.

Furthermore, if the guide for the weld nut welded to the workpiece protrudes from the back side of the workpiece's welded surface, the bolt fastened to the weld nut may come into direct contact with the guide, placing a large load on the welded point of the weld nut. For this reason, it is necessary to adjust the height of the weld nut guide so that it does not protrude from the back side of the workpiece's welded surface. However, as a result of such adjustment, if the workpiece is thin, the guide will also be low, which can make it difficult to determine whether the guide is fitted into the hole when placing the weld nut on the workpiece.

One aspect of the present disclosure aims to enable good fastening of weld nuts while minimizing the difficulty of the work.

One aspect of the present disclosure is a method for manufacturing a component, comprising: placing a positioning pin in a hole that penetrates a workpiece so that the positioning pin protrudes from the hole; placing a weld nut on the positioning pin that protrudes from the workpiece; and welding the weld nut placed on the positioning pin to the workpiece by projection welding. The weld nut has a threaded hole, an opening, and an end face. The threaded hole penetrates the weld nut. The opening is located at the end of the threaded hole. The end face surrounds the opening. The weld nut placed on the positioning pin that protrudes from the workpiece has an end face facing the workpiece, the positioning pin is inserted into the threaded hole, and a surrounding portion is arranged at or near the opening of the weld nut to surround the positioning pin.

With the above configuration, the circumferential portion can cover the gap between the positioning pin and the inner surface of the screw hole. This prevents spatter generated during projection welding from entering the screw hole without interfering with the work required to project weld the weld nut. This reduces the difficulty of the work and enables successful fastening of the weld nut.

In one aspect of the present disclosure, the circumference may be provided on the weld nut.
According to the above configuration, the workload of positioning the circumferential portion during projection welding is reduced.
In one aspect of the present disclosure, the circumferential portion may be deformable by fastening a bolt into the screw hole.

According to the above configuration, it is possible to prevent the circumferential portion from interfering with the fastening of the weld nut and the bolt.
In one aspect of the present disclosure, the workpiece may be constructed from high-tensile steel.

In order to achieve sufficient joint strength when welding to a workpiece made of high-tensile steel, the welding current value and welding temperature may need to be increased, but this can result in increased spatter. In contrast, with the above configuration, even if increased projection welding current generates a large amount of spatter, the spatter can be prevented from penetrating into the threaded hole. This makes it possible to increase the current value when projection welding a weld nut to a workpiece made of high-tensile steel, allowing the weld nut to be welded to the workpiece with sufficient joint strength.

One aspect of the present disclosure is a weld nut comprising a threaded hole, an opening, an end face, and a circumferential portion. The threaded hole passes through the weld nut. The opening is located at an end of the threaded hole. The end face surrounds the opening. The circumferential portion is provided at or near the opening. The weld nut is configured to be projection welded to a workpiece having a hole. When projection welding is performed, a positioning pin is positioned to protrude from the hole in the workpiece, and the weld nut is positioned so that the end face faces the workpiece and the positioning pin is inserted into the threaded hole. The circumferential portion is configured to encircle the positioning pin.

With the above configuration, the circumferential portion can cover the gap between the positioning pin and the inner surface of the screw hole. This prevents spatter generated during projection welding from entering the screw hole without interfering with the work required to project weld the weld nut. This reduces the difficulty of the work and enables successful fastening of the weld nut.

In one aspect of the present disclosure, the circumferential portion may be deformable by fastening a bolt into the screw hole.
According to the above configuration, it is possible to prevent the circumferential portion from interfering with the fastening of the weld nut and the bolt.

1 is an explanatory diagram showing a cross section of a weld nut, a workpiece, an electrode and a positioning pin in a welding device. FIG. 10A and 10B are explanatory diagrams illustrating a method for joining a circumferential portion to a weld nut. FIG. 10 is an explanatory diagram of fastening a bolt to a weld nut welded to a workpiece. 1 is a flowchart of a method for manufacturing a member by projection welding.

Embodiments of the present disclosure will be described below with reference to the drawings. Note that the embodiments of the present disclosure are in no way limited to the following embodiments, and various forms may be adopted as long as they fall within the technical scope of the present disclosure.

[1. Weld Nut]
Weld nut 1 is made of a metal such as iron and is welded to workpiece 2 having hole 20 by projection welding (see FIG. 1 ). Weld nut 1 has threaded hole 10, first and second end faces 11, 12, flange portion 13, protrusion 14, and circumferential portion 15.

The threaded hole 10 is provided so as to pass through the weld nut 1. An internal thread 10B is provided on the inner peripheral surface of the threaded hole 10, and the internal thread 10B can be fastened with a bolt.
The first and second end surfaces 11, 12 are provided so as to surround the openings located at both ends of the screw hole 10. The first end surface 11 is flat.

The flange portion 13 is provided to surround the opening 10A of the screw hole 10 in the first end surface 11.
The protrusions 14 are portions to be melted by projection welding, and are configured as a plurality of protrusions provided on the first end surface 11 at substantially regular intervals so as to surround the opening 10A. The number of protrusions may be determined as appropriate.

[2. Orbital Section]
The circumferential portion 15 is provided at a position near the opening 10A on the inner circumferential surface of the screw hole 10. The circumferential portion 15 is a ring-shaped portion having a flat shape that expands in the radial direction, and is provided so as to protrude from the inner circumferential surface of the screw hole 10 (see FIG. 1). The circumferential portion 15 is also provided so as to go around the inner circumferential surface.

Specifically, a groove 16 is formed around the edge of the opening 10A of the threaded hole 10 on the first end face 11 of the weld nut 1, surrounding the opening 10A (see Figure 2). A wall portion 17 is also formed adjacent to the outside of the groove 16. The wall portion 17 protrudes from the first end face 11 and surrounds the groove 16. The surrounding portion 15 is then placed in the groove 16, and the wall portion 17 is pressed, crushing and expanding it toward the groove 16, thereby joining the surrounding portion 15 to the inner circumferential surface of the threaded hole 10.

Of course, the circumferential portion 15 may be joined to the inner surface of the threaded hole 10 by a method other than that described above, and the circumferential portion 15 may not be joined to the weld nut 1, but may instead be provided as a portion that protrudes from the inner surface of the threaded hole 10 during the process of forming the weld nut 1 from the base material, for example.

Furthermore, the circumferential portion 15 may be provided, for example, further back in the screw hole 10. It is preferable that the circumferential portion 15 be located closer to the opening 10A than the female thread 10B in the screw hole 10. The circumferential portion 15 may be located, for example, on the edge of the opening 10A, or may be joined to the first end face 11 on the outside of the screw hole 10 so as to cover the periphery of the edge of the opening 10A.

The surrounding portion 15 is made of a low-rigidity metal so that it is pressed and deformed by the bolt 4 threaded into the female thread 10B when the bolt is tightened into the threaded hole 10 (see Figure 3).

[3. Work]
The workpiece 2 to which the weld nut 1 is welded is, for example, a plate-shaped member (see FIG. 1 ). More specifically, the workpiece 2 may be, for example, a thin plate used to form the body of a vehicle. However, the workpiece 2 is not limited to this, and the weld nut 1 can be welded to workpieces 2 of various shapes.

The workpiece 2 may also be made of, for example, high-tensile steel. Of course, the workpiece 2 is not limited to this, and may be made of various metals such as steel or iron.
The workpiece 2 also has at least one hole 20 that penetrates the workpiece 2 in the thickness direction from the first surface 21 to the second surface 22 .

[4. Manufacturing method of member]
The welding device 3 of this embodiment used for projection welding includes an electrode 30 and a positioning pin 31 (see FIG. 1 ). The positioning pin 31 is made of an insulating material (e.g., ceramic) and has a tapered shape. The electrode 30 has a hole 30A formed therein, and the positioning pin 31 is disposed in the hole 30A. The welding device 3 floats the positioning pin 31 by letting air out, causing the positioning pin 31 to protrude from the electrode 30.

In this embodiment, a component is manufactured by welding a weld nut 1 around a hole 20 in a workpiece 2 by projection welding using a welding device 3. Below, the method for manufacturing this component is explained using the flowchart in Figure 4.

In S100, the workpiece 2 is placed on the electrode 30 so that the holes 20 and 30A overlap. At this time, the second surface 22 of the workpiece 2 abuts against the electrode 30. Then, floating is performed, and the positioning pin 31 is positioned so that it passes through the holes 20 and 30A and protrudes from the first surface 21.

In S105, the weld nut 1 is placed on the first surface 21 so that the positioning pin 31 protruding from the first surface 21 is inserted into the threaded hole 10 (see Figure 1). At this time, the first end face 11 of the weld nut 1 faces the area surrounding the hole 20 on the first surface 21 of the workpiece 2. As described above, the first end face 11 is flat, and a gap is formed between the area surrounding the opening 10A on the first end face 11 and the first surface 21. The protrusion 14 on the first end face 11 either abuts the first surface 21 of the workpiece 2 or faces the first surface 21 with a small gap.

In addition, at this time, the circumferential portion 15 provided in the threaded hole 10 of the weld nut 1 is positioned so as to surround the positioning pin 31, and the circumferential portion 15 covers the gap between the inner surface of the threaded hole 10 and the positioning pin 31. Specifically, the gap may be completely filled by the circumferential portion 15, or a small gap may be present between the circumferential portion 15 and the positioning pin 31.

In S110, current is passed through the protrusion 14 on the first end surface 11 of the weld nut 1 via the electrode 30 to perform projection welding. At this time, the flange portion 13 is pressed toward the workpiece 2, causing the protrusion 14 to come into contact with the first surface 21 of the workpiece 2 and placing the protrusion 14 in a pressurized state.

Then, the bolt 4 inserted from the second surface 22 side of the workpiece 2 to which the weld nut 1 has been welded is fastened to the weld nut 1 (see Figure 3). When the bolt 4 is threaded into the internal thread 10B of the screw hole 10, the bolt presses against the circumferential portion 15, deforming it.

5. Modifications
In this embodiment, the surrounding portion 15 is provided on the weld nut 1, but the surrounding portion 15 and the weld nut 1 may be separate components. In step S105 of the manufacturing method shown in FIG. 4 , when the weld nut 1 is placed on the workpiece 2, the surrounding portion 15 may be positioned so that it similarly surrounds the positioning pin 31 at or near the opening 10A of the screw hole 10.

Specifically, for example, the wrapping portion 15 may first be positioned so that it wraps around (or is penetrated by) the positioning pin 31 protruding from the first surface 21 of the workpiece 2. Then, the weld nut 1 may be placed on the workpiece 2 so that the positioning pin 31 with the wrapping portion 15 positioned thereon is inserted into the screw hole 10.

Alternatively, for example, the circumferential portion 15 may first be placed at or near the opening 10A of the threaded hole 10 in the weld nut 1. Specifically, the circumferential portion 15 may be placed on the inner surface of the threaded hole 10 or on the edge of the opening 10A, or the circumferential portion 15 may be placed on the outside of the threaded hole 10 in contact with the first end face 11 so as to cover the periphery of the edge of the opening 10A. The weld nut 1 may then be placed on the workpiece 2 so that the positioning pin 31 is inserted into the threaded hole 10 and the circumferential portion 15.

Even in such a case, the gap between the inner peripheral surface of the screw hole 10 and the positioning pin 31 can be covered by the surrounding portion 15 in the same manner.
6. Effects
(1) According to the above embodiment, the surrounding portion 15 can cover the gap between the positioning pin 31 and the inner peripheral surface of the threaded hole 10. This prevents spatter generated by projection welding from entering the interior of the threaded hole 10 without interfering with the work of welding the weld nut 1 to the workpiece 2. This makes it possible to properly fasten the weld nut 1 while minimizing the difficulty of the work.

Here, by increasing the distance between the opening 10A of the threaded hole 10 and the protrusion 14 on the first end surface 11 of the weld nut 1, it is possible to prevent spatter generated during projection welding from entering the interior of the threaded hole 10. This allows the current value during projection welding to be increased, improving joint strength. However, increasing this distance increases the size of the weld nut 1, which may reduce design freedom or increase the weight of the components manufactured by projection welding. In contrast, according to the above embodiment, it is possible to prevent spatter from entering the interior of the threaded hole 10 without increasing the size of the weld nut 1.

There is also a known method of using the air used to float the positioning pin 31 to prevent spatter generated during projection welding from entering the threaded hole in the weld nut. Specifically, this method involves forming at least one groove on the outer surface of the positioning pin, and allowing air to flow through the groove from the hole in the workpiece, thereby eliminating spatter heading toward the threaded hole.

However, with the above method, floating and spatter removal are performed simultaneously, requiring the outflow of large volumes of air at high pressure, which increases costs and raises concerns about increased noise. Furthermore, because the pressure increases when floating the positioning pin, greater force must be applied to the weld nut to pressurize the protrusion during projection welding. Furthermore, if there is an imbalance in the air flow from each groove in the positioning pin, the weld nut may become misaligned, resulting in inconsistent pressure on the protrusion. Furthermore, if the distance between the opening of the screw hole and the protrusion is long, a larger volume of air must be outflowed to remove spatter, increasing costs.

In contrast, according to the above embodiment, it is possible to prevent spatter from entering the interior of the screw hole 10 without increasing the amount of air required for floating. This makes it possible to prevent spatter from entering the interior of the screw hole 10 while suppressing increases in costs and noise.

(2) Furthermore, the circumferential portion 15 is provided on the weld nut 1. Therefore, the workload of placing the circumferential portion 15 during projection welding is reduced.
(3) Furthermore, the surrounding portion 15 can be deformed by fastening the bolt 4 into the threaded hole 10. Therefore, the surrounding portion 15 can be prevented from interfering with the fastening of the weld nut 1 and the bolt 4.

(4) Furthermore, when projection welding a workpiece made of a hard material such as high-tensile steel, the projection welding current value may be increased and the welding temperature may be raised to achieve sufficient joint strength. However, this may result in a large amount of spatter being generated. In contrast, according to the above embodiment, even if the amount of spatter generated increases due to the increased projection welding current value, the spatter can be prevented from penetrating into the threaded hole 10. Therefore, a weld nut can be welded to a workpiece 2 made of high-tensile steel with sufficient joint strength by projection welding.

7. Other Embodiments
(1) In the above embodiment, the weld nut 1 is provided with a flange portion 13. However, the weld nut 1 does not have to be provided with a flange portion 13, and may have a shape such as a square nut or a hexagonal nut.

(2) The circumferential portion 15 is ring-shaped and has a flat shape that expands in the radial direction. However, this is not limited to this, and the circumferential portion 15 may have various shapes as long as it is able to cover the gap between the inner surface of the screw hole 10 and the positioning pin 31.

(3) Furthermore, in the member manufacturing method of the above embodiment, the positioning of the weld nut 1 is performed using a positioning pin 31 that protrudes from the electrode 30 by floating. However, the positioning pin 31 may be provided so as to protrude from the electrode 30 by a method other than floating. Specifically, for example, the positioning pin 31 disposed in the hole 30A may be displaced by a drive unit such as a motor, causing the positioning pin 31 to protrude from the electrode 30. Also, for example, the end of the positioning pin 31 may be joined to the electrode 30 so as to protrude from the electrode 30.

(4) Multiple functions possessed by one component in the above embodiments may be realized by multiple components, or one function possessed by one component may be realized by multiple components. Also, multiple functions possessed by multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

1...weld nut, 10...screw hole, 10A...opening, 11...first end surface, 14...projection portion, 15...circumferential portion, 2...workpiece, 20...hole portion, 21...first surface, 30...electrode, 31...positioning pin, 4...bolt.

Claims (4)

A method for manufacturing a component, comprising:
disposing a positioning pin in a hole that penetrates the workpiece so that the positioning pin protrudes from the hole;
placing a weld nut on the positioning pin protruding from the workpiece;
and welding the weld nut disposed on the positioning pin to the workpiece by performing projection welding.
The weld nut is
a threaded hole passing through the weld nut;
an opening located at an end of the screw hole;
an end surface surrounding the opening,
The weld nut placed on the positioning pin protruding from the workpiece has the end face facing the workpiece, the positioning pin inserted into the screw hole, and a surrounding portion is arranged at or near the opening of the weld nut so as to surround the positioning pin,
The circumferential portion is deformable by fastening a bolt to the screw hole.
Manufacturing method of components. A method for manufacturing the member according to claim 1,
The circumferential portion is provided on the weld nut. A method for manufacturing the member according to claim 1 or 2 , comprising:
The workpiece is made of high-tensile steel. A weld nut,
a threaded hole passing through the weld nut;
an opening located at an end of the screw hole;
an end surface surrounding the opening;
a circumferential portion provided at or near the opening,
The weld nut is configured to be projection-welded to a workpiece having a hole, and when the projection welding is performed, a positioning pin is arranged to protrude from the hole of the workpiece, and the weld nut is arranged so that the end face faces the workpiece and the positioning pin is inserted into the screw hole,
The circumferential portion is configured to circumferentially surround the positioning pin and is deformable by fastening a bolt into the screw hole.
Welding nuts.