JP5819809B2 - How to fasten pierce nuts - Google Patents

Description

  The present invention relates to a method for fastening a pierce nut.

  Conventionally, a pierce nut fastened to a work by a press is known. The pierce nut includes a nut body in which a screw hole is formed, and an inner cylinder part and an outer cylinder part that extend downward from the lower surface of the nut body and concentrically with the screw hole. An annular recess opening downward is formed between the inner cylinder part and the outer cylinder part. The inner cylinder part extends longer than the outer cylinder part, and thereby the tip part of the inner cylinder part is positioned below the tip part of the outer cylinder part. Moreover, the outer peripheral surface of the inner cylinder part is a taper which expands diameter downward.

  The pierce nut is usually fastened to the workpiece as follows. First, on a die having an upper surface with a hole fitted on the outer periphery of the inner cylindrical portion of the pierce nut, and an annular protrusion formed on the periphery of the hole and inserted into the annular recess of the pierce nut, Place the workpiece. Next, the pierce nut is held at the tip of the punch, and the punch is advanced until the inner cylindrical portion of the pierce nut is fitted into the hole of the die. Then, the work is punched by the inner cylindrical portion of the pierce nut acting as a piercing punch, and a hole is formed in the work. At the same time, the tip of the outer cylinder part comes into contact with the work, so that the work at the periphery of the formed hole is pushed into the annular recess of the pierce nut by the annular protrusion of the die and caulked. As a result, the work is filled in the annular recess, and the work does not come into close contact with the tapered outer peripheral surface of the inner cylinder part. As described above, the pierce nut is fastened to the workpiece.

  In addition, a technique for forming a hole in a workpiece in advance before punching out a pierce nut is disclosed (for example, see Patent Document 1). In this technique, since a hole is formed in the workpiece in advance, it is not necessary to punch the workpiece with a pierce nut.

JP 2010-071313 A

  By the way, when a pierce nut is fastened to a work having high strength and low ductility, a work is easily cracked in the annular recess. In addition, the work is not sufficiently filled in the annular recess, and a gap is easily formed in the annular recess. For this reason, there is a possibility that the fastening strength of the pierce nut with respect to the workpiece becomes insufficient.

  Moreover, in order to form a hole in a workpiece | work beforehand like the technique of patent document 1, the process for forming a hole in a workpiece | work is separately needed. That is, there is a problem in that the formation of holes and the fastening by caulking, which are the advantages of the pierce nut, cannot be performed in one step, and the work becomes complicated. Accordingly, there is a demand for a method for fastening a pierce nut in which the formation of holes and the fastening by caulking are performed in one step and high fastening strength is obtained.

  This invention is made | formed in view of the above, The objective is to provide the fastening method of the pierce nut which can perform fastening by formation of a hole and crimping by 1 process, and can obtain high fastening strength.

In order to achieve the above object, the present invention provides a nut body (for example, a nut body 10 to be described later) in which a screw hole (for example, a screw hole 11 to be described later) is formed, and a lower surface (for example, a nut body to be described later) of the nut body. An inner cylinder part (for example, an inner cylinder part 12 described later) and an outer cylinder part (for example, an outer cylinder part 13 described later) extending downward from the lower surface 10b) of the screw hole and concentrically with the screw hole, By extending the inner cylinder part longer than the outer cylinder part, the tip part of the inner cylinder part (for example, the tip part 120 of the inner cylinder part to be described later) becomes the tip part of the outer cylinder part (for example, the outer part to be described later). Provided is a method of fastening a pierce nut (for example, a pierce nut 1 described later) positioned below the distal end portion 130) of the tube portion.
According to the fastening method of the pierce nut according to the present invention, a rising portion having a predetermined height (for example, a height h described later) at a predetermined part of a workpiece (for example, a workpiece w1 described later) according to the shape of the pierce nut. (For example, a preforming step for forming a rising portion T described later), a hole (for example, a hole 91 described later) that can be fitted to the outer periphery of the inner cylindrical portion, and a periphery of the hole, and A die having an annular protrusion (for example, an annular protrusion 92 described later) that can be inserted into an annular recess (for example, an annular recess 14 described later) formed between the inner cylinder portion and the outer cylinder portion. For example, on the die 9) to be described later, the work is placed so that the rising portion is positioned in the vicinity of the peripheral edge of the annular protrusion, and in this state, until the inner tube portion is fitted into the hole portion. By punching the workpiece with the pierce nut, the pin A fastening step of fastening a snut to the workpiece, and in the preforming step, the height of the rising portion is determined from the thickness of the workpiece (for example, a thickness t described later) in the extension direction. The rising portion is formed so as to be larger than a value obtained by subtracting a distance (for example, a distance d described later) from the distal end portion of the cylindrical portion to the distal end portion of the outer cylindrical portion.

In the fastening method according to the present invention, first, a rising portion having a predetermined height is formed at a predetermined portion of the workpiece according to the shape of the pierce nut before the formation of holes and the fastening by caulking. At this time, the height of the rising portion is set to be larger than the value obtained by subtracting the distance from the distal end portion of the inner cylindrical portion to the distal end portion of the outer cylindrical portion in the extending direction from the thickness of the workpiece.
And a hole that can be fitted to the outer periphery of the inner cylinder, and an annular protrusion that is formed on the periphery of the hole and can be inserted into an annular recess formed between the inner cylinder and the outer cylinder. The workpiece is placed on the die having the rising portion positioned in the vicinity of the peripheral edge of the annular protrusion.
Next, the workpiece is punched out with a pierce nut until the inner tube portion is fitted into the hole portion. Then, first, the inner cylinder portion acts as a piercing punch to form a hole in the workpiece. Further, since the rising portion set at the predetermined height is arranged in the vicinity of the peripheral edge of the annular protrusion, the tip of the outer cylinder portion does not contact the workpiece until the hole is formed, Caulking is not started.
After the hole is formed, when the inner cylinder part is fitted into the hole part, the tip part of the outer cylinder part comes into contact with the work, so that the work at the peripheral part of the formed hole is annularly formed by the annular protrusion. It is pushed into the recess and caulked. That is, when caulking is performed, since a hole is already formed and one end side of the workpiece is a free end, the material constituting the workpiece is easy to flow and easily extend. As a result, the work is hardly cracked, and the work is sufficiently filled in the annular recess.
Therefore, according to the present invention, the fastening by the formation of the hole and the caulking is performed in one step of the fastening step, and the pierce nut can be fastened to the workpiece with high fastening strength.

  ADVANTAGE OF THE INVENTION According to this invention, the fastening method of the pierce nut which can perform fastening by formation of a hole and crimping by 1 process, and high fastening strength can be provided.

It is sectional drawing of the pierce nut fastened by the workpiece | work by the fastening method of the pierce nut which concerns on one Embodiment of this invention. It is a figure for demonstrating the fastening method of the pierce nut which concerns on the said embodiment. It is a figure for demonstrating the fastening method of the conventional pierce nut.

  An embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of a pierce nut fastened to a workpiece by a pierce nut fastening method according to an embodiment of the present invention. As shown in FIG. 1, the pierce nut 1 includes a nut body 10, an inner cylinder part 12, and an outer cylinder part 13.
In the present embodiment, the nut body 10 has a substantially square shape in plan view. An upper surface 10a of the nut body 10 is a flat surface, and a screw hole 11 extending vertically downward from the upper surface 10a is formed at the center of the nut body 10.

  The inner cylinder portion 12 extends downward from the lower surface 10 b of the nut body 10 and concentrically with the screw hole 11. The outer diameter of the inner cylinder portion 12 is set to a size that fits into a hole portion 91 of the die 9 described later. The outer peripheral surface 121 of the inner cylinder part 12 is formed in the taper shape which expands diameter downward. Thereby, it becomes difficult to remove the pierce nut 1 from the workpiece W1, and the fastening strength is improved. Moreover, the front end surface of the front-end | tip part 120 of the inner cylinder part 12 is a plane, and the cutting edge 120a is provided in the outermost part over the perimeter.

  The outer cylinder portion 13 is provided outside the inner cylinder portion 12 and extends downward from the outer peripheral portion of the lower surface 10 b of the nut body 10 and concentrically with the screw hole 11. The inner periphery 130a of the outer cylinder part 13 is formed including a taper. Thereby, it becomes difficult to remove the pierce nut 1 from the workpiece W1, and the fastening strength is improved. The inner cylindrical portion 12 extends longer than the outer cylindrical portion 13, and the distal end portion 120 of the inner cylindrical portion 12 is positioned below the distal end portion 130 of the outer cylindrical portion 13.

  Between the inner cylinder part 12 and the outer cylinder part 13, the annular recessed part 14 opened toward the downward direction is formed. In the present embodiment, since the nut body 10 has a substantially square shape in plan view, the annular recess 14 has a substantially square ring shape in plan view. The width of the annular recess 14 is set to be larger than the width of the annular protrusion 92 of the die 9 described later, and the annular protrusion 92 can be inserted into the annular recess 14 via the workpiece W1.

The pierce nut 1 having the above configuration is fastened to the workpiece W1 using a punch (not shown) and a die 9 shown in FIG.
A pierce nut 1 is held at the tip of a punch (not shown). The punch is provided with a drive source for moving the punch forward and backward with respect to the die 9.

A hole 91 extending vertically downward is formed at the center of the die body 90 constituting the die 9. The inner diameter of the hole portion 91 is set to a size that allows the outer periphery of the inner cylindrical portion 12 of the pierce nut 1 to be fitted. An annular protrusion 92 that protrudes upward and can be inserted into the annular recess 14 is formed on the periphery of the hole 91.
In the present embodiment, since the annular recess 14 has a substantially square ring shape in plan view, the annular protrusion 92 has a substantially square ring shape in plan view. The protrusion height of the annular protrusion 92 is set to be smaller than the extending length of the inner cylinder part 12. The upper surface 92a of the annular protrusion 92 is a flat surface, and the corners of the annular protrusion 92 are chamfered to have an R shape.

  As the workpiece W1, a plate-shaped one is used, and the material is not particularly limited. A material having high strength and low ductility can also be used.

  The fastening method of the pierce nut 1 which concerns on this embodiment has a preforming process and a fastening process. In the preforming process, preforming is performed on the workpiece W1 prior to the fastening process. In the fastening process, the workpiece W1 that has been preformed is fastened by hole formation and caulking. That is, in the fastening method of the pierce nut 1 according to this embodiment, the hole formation and the fastening by caulking are performed in one step of the fastening step.

Hereinafter, the fastening method of the pierce nut 1 according to the present embodiment will be described with reference to FIGS. 2 and 3 while comparing with the conventional fastening method of the pierce nut.
Here, FIG. 2 is a figure for demonstrating the fastening method of the pierce nut 1 which concerns on this embodiment, and FIG. 3 is a figure for demonstrating the fastening method of the conventional pierce nut 2. As shown in FIG. More specifically, FIG. 2 and FIG. 3 are enlarged cross-sectional views when the fastening process of each method is executed. (A) is before the hole is formed in the workpiece W1, and (B) is the hole formed. (C) is a diagram showing when the work W1 is caulked, and (D) is a diagram showing when the fastening is completed.

As described above, in the present embodiment, in the pre-forming step prior to the fastening step, the rising portion T having a predetermined height h is formed at a predetermined portion of the workpiece W1 according to the shape of the pierce nut 1 (FIG. 2). (See (A)).
Specifically, in this embodiment, the shape of the nut body 10 is substantially square in plan view, and the shape of the annular recess 14 is substantially square, so that the shape substantially coincides with the outer periphery of the square annular shape. Thus, the rising portion T is formed on the workpiece W1.
As shown in FIGS. 2A and 2B, the height of the rising portion T is determined from the thickness t of the workpiece W1 in the extending direction (vertical direction in FIG. 2). Is set to a value larger than the value obtained by subtracting the distance d from the tip portion 130 of the outer tube portion 13 to the outer tube portion 13.

  The pre-forming process of the present embodiment can be performed simultaneously with the press-forming process for forming the workpiece W1 into a product shape. That is, the rising portion T is formed by press molding at the same time as the product shape is press molded. Thereby, it is not necessary to provide a preforming process separately.

Next, in the fastening process of the present embodiment, as shown in FIG. 2A, the workpiece W <b> 1 is placed on the die 9 so that the rising portion T is positioned on the peripheral edge of the annular protrusion 92. In this state, when a punch (not shown) that holds the pierce nut 1 at the tip is advanced, the tip portion 120 of the inner cylinder portion 12 of the pierce nut 1 comes into contact with the workpiece W1.
On the other hand, in the conventional fastening process, as shown in FIG. 3A, since the workpiece W2 is not preformed, the position where the workpiece W2 is placed is not particularly limited.

Next, in the fastening process of the present embodiment, as shown in FIG. 2B, when the punch is further advanced, the distal end portion 120 of the inner cylindrical portion 12 reaches the height of the upper surface 92a of the annular protrusion 92. Then, the workpiece W1 is punched out by the cutting edge 120a provided on the outermost side of the distal end portion 120 of the inner cylinder portion 12, and a hole is formed in the workpiece W1. At this time, since the height h of the rising portion T is set to a value larger than t-d as described above, the distal end portion 130 of the outer cylinder portion 13 does not contact the workpiece W1, and caulking is not started. .
On the other hand, in the conventional fastening process, as shown in FIG. 3 (B), before the hole is formed in the workpiece W2, the distal end portion 130 of the outer cylinder portion 13 comes into contact with the workpiece W2, and caulking is started. At this time, since no hole is formed in the work W2, the flow of the material constituting the work W2 is limited, and it is difficult to extend.

Next, in the fastening process of the present embodiment, as shown in FIG. 2C, when the punch is further advanced and the inner cylinder portion 12 is fitted into the hole portion 91, the peripheral portion of the formed hole is formed. The workpiece W1 is pushed into the annular recess 14 by the annular protrusion 92 and caulked. At this time, since a hole is already formed and one end side of the workpiece W1 is a free end, the material constituting the workpiece W1 is easy to flow and easily extends. Therefore, the thickness of the caulking portion W1k of the work is sufficiently secured. As a result, as shown in FIG. 2 (D), it is possible to suppress cracks in the wall portion W1a of the workpiece, and to sufficiently fill the tip portion W1c and the push-in portion W1b of the workpiece into the annular concave portion 14, thereby achieving high fastening. Strength is obtained.
On the other hand, in the conventional fastening process, since the caulking starts from the stage where the material flow is restricted as described above, the thickness of the caulking portion W2k of the workpiece is reduced as shown in FIG. ing. Therefore, as shown in FIG. 3D, the work wall W2a is cracked, and the work tip end W2c and the push-in part W2b cannot be sufficiently filled in the annular recess 14 to obtain high fastening strength. Absent.

  Therefore, according to this embodiment, the fastening by the formation of the hole and the caulking is performed in one step of the fastening step, and the pierce nut 1 can be fastened to the workpiece W1 with high fastening strength.

The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above embodiment, the nut body 10 has a substantially square shape in plan view, but is not limited thereto, and may have a substantially circular shape in plan view. In this case, since the shape of the annular recess and the shape of the annular protrusion are substantially perfect circles in plan view, the shape of the rising part is substantially the same as the outer periphery of the true circle shape.
Moreover, in the said embodiment, although the one plate-shaped workpiece | work was used as the workpiece | work W1, you may use the workpiece | work which laminated | stacked the plate material of 2 or more sheets, for example.

DESCRIPTION OF SYMBOLS 1 ... Pierce nut 9 ... Die 10 ... Nut main body 10b ... Lower surface of nut main body 11 ... Screw hole 12 ... Inner cylinder part 13 ... Outer cylinder part 14 ... Annular recessed part 91 ... Hole part 92 ... Annular protrusion 120 ... Inner cylinder part Tip portion 121 ... Outer peripheral surface of inner cylinder portion 130 ... Tip portion of outer cylinder portion W1 ... Workpiece T ... Standing portion d ... Distance h ... Height t ... Thickness

Claims (1)

A nut body in which a screw hole is formed; and an inner cylinder part and an outer cylinder part extending downwardly from the lower surface of the nut body and concentrically with the screw hole, wherein the inner cylinder part is more than the outer cylinder part. In the fastening method of the pierce nut in which the distal end portion of the inner cylinder portion is positioned below the distal end portion of the outer cylinder portion by extending the
According to the shape of the pierce nut, a preforming step for forming a rising portion having a predetermined height at a predetermined part of the workpiece,
A hole that can be fitted to the outer periphery of the inner cylinder, and an annular protrusion that is formed on the periphery of the hole and that can be inserted into an annular recess formed between the inner cylinder and the outer cylinder. The workpiece is placed on a die having a position where the rising portion is positioned in the vicinity of the peripheral edge of the annular protrusion, and in this state, the pierce nut is fitted until the inner tube portion is fitted into the hole portion. And a fastening step of fastening the pierce nut to the workpiece by punching the workpiece with
In the preforming step, the height of the rising portion is greater than a value obtained by subtracting the distance from the tip of the inner cylinder to the tip of the outer cylinder in the extending direction from the thickness of the workpiece. A method for fastening a pierce nut, wherein the rising portion is formed as described above.

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