JP2007170645A - Insert nut and work fastening structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insert nut which fastens a plurality of relatively soft works by combination with a screw member, and has a secure caulking action. <P>SOLUTION: The insert nut 1 consists of a shaft part 3 and a head part 2 which is larger than the shaft part 3. A lower hole part 11 for a female screw forming is formed at a tip end of the shaft part 3 and a hollow hole part 12 of which diameter is longer than that of the lower hole part 11 for the female screw forming is provided from the lower hole part 11 to the head part 2 and a hollow hole 10 with steps is formed from the lower hole part 11 for the female screw forming and the hollow hole part 12. As an outer circumference of the shaft part 3 is a shaft form with steps wherein an outer circumference of the lower hole part 11 for the female screw forming is small and an outer circumference of the hollow hole part 12 is large, the insert nut is calked with relatively low torque when a screw member is screwed in. Stable caulking action is provided as a caulking part evenly expands in an outward direction without the shaft part being twisted when screwing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fastening part and a fastening structure for fastening a plurality of plate-like workpieces with a screw member and a nut screwed to the screw member, and in particular, an insert nut that enables fastening work from one direction. And a work fastening structure using the insert nut.

  Generally, when a plurality of workpieces are fastened, screw members are directly screwed to the workpiece and fastened, or through holes are formed in the workpiece, screw members are inserted into the through holes, and nut members are inserted into the legs from the other side. Are screwed together and the workpiece is sandwiched and fastened by the screw member and the nut member. In these fastening operations, when the screw member is screwed into one work and the other work is fixed, the work to which the screw member is screwed has a predetermined fastening strength from the necessity of forming a female screw. For this reason, a thickness greater than a certain level is required for screwing the screw member. If the workpiece is thin, the female screw will be crushed, and the screw member will not be fastened sufficiently, resulting in insufficient fastening strength. Yes.

  In addition, when fastening with a screw member and a nut member sandwiching each other's work, it is necessary to work from both sides of the work, so if there is no predetermined space on both sides, the fastening work by the screw member and the nut member There is a problem that cannot be done. In particular, recently, products have been downsized, parts used for the products have become thinner, and the fastening work of these products has become complicated.

  A fastening structure that is being used in recent years in view of the current situation is, for example, a fixing structure using a blind nut disclosed in JP-A-4-15309. This is mainly used for screwing parts to the frame of a motorcycle, and this blind nut is a nut member fixed to the back of a plate-like member. In addition, there are those that perform fixing work from the outside. An improvement of such a fixing structure is shown in FIGS. This relates to a blind nut, and is a cylindrical female screw body having a head 102, and a blind nut material 101 having a thin-walled portion 112 whose inner diameter is cut off at the neck is used. The portion of the female screw 111 is inserted in the head direction by using a screw tool (not shown) screwed into the female screw 111 while being inserted into the pilot hole 106 of the member 105 and pressing the back surface of the head to the surface of the plate member 105. By pulling up, the thin portion 112 bulges outwardly to form a caulking portion 113, and the plate member 105 is sandwiched and fixed between the caulking portion 113 and the head portion 102. It is a blind nut. Then, the pilot hole 106 of the plate-like member 105 is formed in a countersink that extends to the outer surface, while at least one bulging portion 125 that fills the inner peripheral root portion is formed on the back surface of the head of the blind nut material 101, The bulging portion 125 is configured to have a mountain shape in which the bulging amount gradually decreases in the circumferential direction on both sides around the top portion having a size matching the inclined surface of the countersink.

JP-A-4-15309

  However, in such a blind nut, a screw tool is screwed into a pre-formed female screw, and the female screw part is pulled up to the head side to form a caulked part, and then the screw is used to fix the work to this. With this blind nut, multiple workpieces cannot be clamped and fixed.For example, even if the workpiece can be clamped and fixed with this blind nut, the caulked portion will pass over time. If it returns even a little, there may be a gap between the workpieces and loosening may occur. Further, since this blind nut has a female screw formed in advance, it requires a large number of manufacturing steps and is expensive. Furthermore, in order to prevent rotation when the screw is screwed into the blind nut, a bulging portion is provided at the inner peripheral root portion of the rear surface of the head of the blind nut so as to sandwich the countersunk hole of the workpiece. Therefore, it is necessary to form a countersink in the prepared hole of the workpiece. In addition, since the bulging portion is required to be formed at the base portion of the back surface of the head as described above, there is a problem that a mold used when manufacturing the bulging portion by forging is complicated.

  The first object of the present invention is to obtain an insert nut that solves such a problem and enables a plurality of relatively soft workpieces to be fastened in combination with a screw member and has a positive caulking action. A second object of the present invention is to obtain a workpiece fastening structure that can quickly fix each other's workpieces with a simple configuration and enables all fastening operations from one side even when there is almost no space on the back surface.

  A first object of the present invention is composed of a shaft portion 3 and a head portion 2 having a larger outer peripheral shape than the shaft portion 3, and a female screw forming pilot hole portion 11 is formed at the tip of the shaft portion 3. A hollow hole 12 having a diameter larger than the diameter of the female screw forming pilot hole 11 is provided from the female pilot hole 11 to the head 2, and the stepped hollow hole 10 is formed from the female screw forming pilot hole 11 and the hollow hole 12. Provided is an insert nut having a stepped shaft shape in which the outer periphery of the shaft portion 3 is narrower than the outer periphery of the female screw forming pilot hole portion 11 and the outer periphery of the hollow hole portion 12 is thicker. To be achieved.

  Further, in addition to this configuration, the stepped shaft shape has a tapered shape with a large head side, so that the caulking action of the shaft portion is surely generated in the hollow portion, and the hollow portion can expand outward. Further, in addition to these configurations, the shaft portion is an insert nut having a plurality of thin strips along the axial direction at equal intervals in the circumferential direction at the caulking position of the hollow hole portion 12, so that the shaft portion by caulking The bulge is even.

  The second object of the present invention is to form an insertion hole 6 into which a shaft portion 3 of the insert nut 1 can be inserted into a plurality of plate-like workpieces 5 fastened to each other. An engagement hole 7 in which the head 2 is engageably fitted is formed in the workpiece 5, while the insert nut 1 is longer than the interval (T) between the front surface and the back surface of the workpiece 5 to be fastened. 3 and a head 2 having a larger outer peripheral shape. A female screw forming pilot hole 11 is formed at the tip of the shaft 3, and the female screw forming pilot hole 11 extends from the female screw forming pilot hole 11 to the head 2. A hollow hole portion 12 having a diameter larger than the diameter of the lower hole portion 11 is provided, and the outer periphery of the shaft portion 3 is thinned at the outer periphery of the female screw forming lower hole portion 11 and the outer periphery of the hollow hole portion 12 is formed thicker. The insert nut 1 is inserted into the insertion hole 6 of the workpiece 5 with a shaft shape. Then, the head 2 is engaged with the engaging hole 7 and the screw member 20 is inserted from the head side, and the screw member 20 is screwed into the female screw forming lower hole portion 11 while forming the female screw. The work fastening structure is such that the seating surface 23 is in contact with the top surface of the head 2 and the hollow hole portion 12 is compressed and caulked by the screw forming pilot hole portion 11 on the end surface of the workpiece 5 to fasten the workpiece 5. Is achieved by providing

  Moreover, in addition to this configuration, the shaft 5 has a work 5 to which a part of the hollow hole 12 and the female screw forming pilot hole 11 are fastened when at least the head 2 is fitted into the engagement hole 7 of the work 5. By using the workpiece fastening structure that protrudes from the back surface of the workpiece, the caulking portion is reliably formed on the back surface of the workpiece.

  According to the present invention, since the outer periphery of the shaft portion has a stepped shape with a thin tip end and a thick head portion, it can be caulked with a relatively low torque when the screw member is screwed. In addition, the caulking portion uniformly bulges outward, and the shaft portion does not twist during screwing, so that a stable caulking action can be obtained. Furthermore, as in the prior art, a screw tool is screwed into a previously formed female screw, the female screw part is pulled up to the head side to form a crimped portion, and then the screw is screwed again. Since the workpiece is directly caulked by the screw member, the work efficiency is improved. Also, a female screw forming pilot hole is provided at the tip of the insert nut, and a screw member is screwed into the female nut while forming a female screw therein, so that the workpiece is inserted between the head of the insert nut and the caulked portion of the shaft portion. It is possible to clamp and fasten, and the fastening work cost can be reduced. In addition, since the caulking portion is always pulled up to the head side by the screw member, the caulking portion does not return even if time passes, and the fastening does not loosen. In addition, since the insert nut can be manufactured only by the forging process, the manufacturing cost can be reduced and can be provided at a low cost. In addition, an engagement hole having a shape corresponding to the rectangular or elliptical head is formed so that the head is engaged with the surface of the work, and then the screw member is screwed. If inserted, the insert nut rotates together with the screw member, so-called idle rotation action does not occur, and firm fastening is ensured. Further, since the thin strip is formed in the axial direction on the shaft portion, when the caulking is performed, the thin strip is uniformly bulged outwardly so as to be torn, so that a predetermined caulking portion without variation is always obtained. In addition, the insert nut is inserted into the insertion hole formed in the workpiece, the screw member is screwed into the hollow hole of the insert nut, and the workpiece is clamped between the head and the caulking portion. It is possible to perform the work from one side, and there is a specific effect that a sufficiently reliable fastening work is possible even if the space on the back surface of the work is narrow.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In FIGS. 1 and 2, reference numeral 1 denotes an insert nut member, and the nut member 1 is integrally formed from a head portion 2 and a shaft portion 3 having a smaller diameter. The head portion 2 and the shaft portion 3 are formed with a stepped hollow hole 10 penetrating the head portion 2 and the shaft portion 3, and the stepped hollow hole 10 is continuous with a female hole forming pilot hole portion 11 formed on the distal end side of the shaft portion. On the head side, a hollow hole 12 having a diameter larger than that of the female screw forming pilot hole 11 is formed. The diameter of the female screw forming pilot hole portion 11 is set to an effective diameter of the screw member 20 screwed into the female screw forming portion 11 or slightly smaller than the effective diameter, and is formed on the leg portion 21 of the screw member 20. The male screw 22 can be screwed in while forming a female screw.

  Further, the outer periphery of the shaft portion 3 is formed at the tip side, that is, the outer periphery of the female screw forming pilot hole portion 11 is thin, and the head side, that is, the outer periphery of the hollow hole portion 12 is formed thick. It is desirable to be located on the pilot hole side. This boundary has a stepped shaft shape, and the stepped shaft shape portion has a tapered shape with a thick head. And by this, even after the male screw 22 is screwed into the female screw forming pilot hole 11 and the seat surface 23 of the screw member 20 contacts the top surface of the head 2 of the insert nut 1, the screwing continues. A force acts outwardly on the shaft portion 3 forming the hollow hole portion 12, and the bulge of this portion is ensured. On the other hand, the stepped shaft-shaped portion may be other than this tapered shape, for example, a stepped slightly stepped shape.

  A male screw 22 is formed in the screw member 20 to the middle of the leg 21, and a screwless portion 24 having a diameter larger than the diameter of the male screw 22 is formed on the head side. The unthreaded portion 24 has a cylindrical shape along the inner diameter of the hollow hole portion 12 of the insert nut 1. The boundary between the unthreaded portion 24 and the male screw 22 is appropriately set at a predetermined position, thereby caulking as shown in FIG. The amount of caulking of the part 13 can be set. That is, if this boundary is formed on the tip end side of the leg portion of the screw member 20, the female screw forming pilot hole portion 11 abuts the tip of the non-threaded portion 24 during caulking, and the amount of caulking is inevitably reduced. If the boundary is formed on the head side, the amount of caulking can be increased, and the amount of caulking can be adjusted by the position of the boundary between the unthreaded portion 24 and the male screw 22.

  Furthermore, since the non-threaded portion 24 of the screw member 20 has a shape along the hollow hole portion 12 of the insert nut 1, the screw member 20 is guided by this at the time of screwing, and the screw member 20 is inclined. Screwing in is avoided. Of course, the screw member 20 has a structure capable of sufficiently exerting the caulking action on the insert nut 1 even if the male screw 22 is formed over the entire length of the leg portion 21.

  Furthermore, the outer shape of the head portion of the insert nut 1 shown in FIGS. 1 and 2 is a substantially rectangular shape larger than the diameter of the shaft portion 3 in this embodiment, but instead of this, a rectangular shape is used. Also good. That is, the head 2 may have a polygonal shape other than these, a substantially rectangular shape such as a gear shape, or an elliptical shape, and the work 5 and the head are prevented from rotating freely with respect to the work 5. The shape is not particularly limited as long as the portion 2 can be engaged with the portion 2.

  On the other hand, a plurality of plate-like workpieces 5 fastened by the insert nut 1 are formed with insertion holes 6 having a diameter into which the shaft portion 3 of the insert nut 1 can be inserted. The work 5 on the contact side is formed with a bottomed rectangular engagement hole 7 having a shape along a substantially rectangular shape that is the outer shape of the head 2. If the outer shape of the head of the insert nut 1 is changed, the shape of the engagement hole 7 inevitably needs to be changed to a shape that roughly follows the outer shape of the head.

  Moreover, the length of the insert nut 1 is longer than the interval (T) between the front and back surfaces of the plurality of workpieces 5 to be fastened in a state where the head 2 is fitted in the engagement hole 7 of the workpiece 5. Particularly, the internal thread forming pilot hole portion 11 of the shaft portion 3 has a size sufficient to protrude from the back surface of the workpiece 5 together with a part of the hollow hole portion 12. Specifically, the length (L) of the insert nut 1 is normally about 1.5 to 3 times the thickness (T) of a plurality of workpieces, and the internal thread forming pilot hole 11 and The stepped shaft-shaped portion on the outer periphery of the shaft portion is configured to completely protrude from the back surface of the workpiece 5.

  When fastening a plurality of workpieces 5 using such an insert nut 1, as shown in FIG. 1, the workpiece 5 having the engagement hole 7 formed on the surface side of the workpiece 5 is formed on the workpiece 5. Insert the insert nut 1 into the insertion hole 6. As a result, the head 2 of the insert nut 1 is fitted into the engagement hole 7 as shown in FIG. 2 and engaged, and then the stepped hollow hole 10 of the insert nut 1 is inserted into the head side as shown in FIG. Then, the screw member 20 is inserted. Thereby, the male screw 22 of the leg portion 21 of the screw member 20 is screwed into the female screw forming pilot hole portion 11 while forming the female screw, and the seat surface 23 of the head portion of the screw member 20 is inserted as shown in FIG. Abutting on the top surface of the head of the nut 1, the internal thread forming pilot hole 11 of the shaft portion 3 of the insert nut 1 is pulled up, so that the shaft portion 3 bulges outward, A caulking portion 13 is formed.

  Subsequently, when the screw member 20 is screwed in, as shown in FIG. 5, the caulking portion 13 comes into contact with the back surface of the work 5, and the plural works 5 are caulked with the head 2 of the insert nut 1. It is clamped between the portions 13 without generating a gap. At this time, since the friction force is acting between the insert nut 1 and the screw member 20 screwed into the insert nut 1, it is difficult for loosening to occur.

  FIGS. 6 and 7 show another embodiment of the insert nut 1 according to the present invention. A plurality of the insert nuts 1 are axially aligned with the caulking position of the shaft portion 3 of the insert nut 1 and spaced at equal intervals in the circumferential direction. A longitudinal groove 4 is formed. Thereby, in the caulking operation, a tensile force is generated in the circumferential direction of the hollow hole portion 12 when the shaft portion 3 is compressed. As a result, cracks are easily formed in the circumferential direction, and the shaft portion is easily bulged. This vertical groove 4 is effective when the shaft portion 3 of the insert nut 1 is cylindrical, but the outer periphery of the shaft portion 3 is not shown, but if the hexagon or higher polygonal shape is used, the shaft portion 3 A thin portion is inevitably formed in relation to the cylindrical stepped hollow hole 10, and a thin portion corresponding to the longitudinal groove 4 is obtained. By forming a plurality of such longitudinal grooves 4 or thin thin strips in the longitudinal direction on the shaft portion 3 at equal intervals in the circumferential direction, the caulking portion 13 that bulges outward evenly can be obtained. become.

  Further, since the periphery of the vertical groove 4 swells from the outer periphery of the shaft portion, it can come into contact with the insertion hole 6 of the workpiece 5, whereby the insert nut 1 can be temporarily fixed. The insert nut 1 can be temporarily fixed in the same manner as described above by making the corner of the shape contact the insertion hole 6 of the workpiece 5. For this reason, even if the workpiece is moved in this state, the workability is improved without shifting. In this embodiment, if the adsorbent for adsorbing and holding the molding powder is applied to the male screw 22 of the screw member 20, it is possible to prevent the molding powder from scattering when the female screw is formed, and it is widely used for assembling electronic equipment. Can be used.

It is a section front view showing an embodiment of the invention. It is a top view which shows the engagement state of the workpiece | work and insert nut of FIG. It is a cross-sectional front view which shows the caulking start state by this invention. It is a cross-sectional front view which shows the bulging state of the axial part of a hollow hole part. It is a cross-sectional front view which shows the crimping completion state by this invention. It is a principal part sectional front view which shows the other Example of the insert nut by this invention. It is the sectional view on the AA line of FIG. It is a principal part cross-sectional front view which shows a prior art example. It is a cross-sectional front view which shows the crimping state of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insert nut 2 Head part 3 Shaft part 4 Longitudinal groove 5 Work piece 6 Insertion hole 7 Engagement hole 10 Stepped hollow hole 11 Female screw formation pilot hole part 12 Hollow hole part 13 Caulking part 20 Screw member 21 Leg part 22 Male screw 23 Seat Surface 24 Screwless part

Claims (5)

The shaft portion (3) and a head portion (2) having a larger outer peripheral shape than the shaft portion are formed, and a female screw forming pilot hole portion (11) is formed at the tip of the shaft portion, from the female screw forming pilot hole portion. An insert nut in which a hollow hole (12) having a diameter larger than the diameter of the female screw forming pilot hole is provided over the head, and a stepped hollow hole (10) is formed from the female screw forming pilot hole and the hollow hole. In (1),
An insert nut characterized in that the outer periphery of the shaft portion has a stepped shaft shape in which the outer periphery of the female screw forming pilot hole portion is narrow and the outer periphery of the hollow hole portion is thick.   The insert nut according to claim 1, wherein the stepped shaft has a tapered shape with a thick head.   The insert nut according to claim 1 or 2, wherein the shaft portion has a plurality of thin strips along the axial direction at equal intervals in the circumferential direction at a caulking position of the hollow hole portion.   An insertion hole (6) into which the shaft portion (3) of the insert nut (1) can be inserted is formed in a plurality of plate-like workpieces (5) fastened to each other, and the head (2) of this insert nut is located. An engagement hole (7) is formed in the work so that the head can be engaged. The insert nut is longer than the interval (T) between the front surface and the back surface of the work to be fastened, and the outer periphery thereof. A female screw forming pilot hole (11) is formed at the tip of the shaft portion, and is larger than the diameter of the female screw forming pilot hole from the female screw forming pilot hole to the head. A hollow hole portion (12) having a diameter is provided, and the outer periphery of the shaft portion has a stepped shaft shape in which the outer periphery of the female screw forming lower hole portion is thin and the outer periphery of the hollow hole portion is formed thick. The head is inserted into the insertion hole and the head is engaged with the engagement hole and the head The screw member (20) is inserted from the side, the screw member is screwed in while forming the female screw in the female screw forming pilot hole, and the seat surface (23) of the screw member contacts the top surface of the head and the workpiece A work fastening structure, wherein the hollow hole portion is compressed and caulked by a screw forming pilot hole portion at an end face to fasten the workpiece. 5. The shaft portion, wherein at least a head portion fits into an engagement hole of a workpiece, a part of the hollow hole portion and a female screw forming pilot hole portion protrude from a back surface of the workpiece to be fastened. The workpiece fastening structure described.

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