JPH10184636A - Screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw positively prevented from falling from an internal thread and advantageous from the viewpoint of manufacturing cost. SOLUTION: A screw 1 is composed of a head and a shank protruded from the center of one end of the head and having a thread on the outer peripheral surface. The shank 3 has a main thread part 31 with a main thread 310 on the outer peripheral surface from the head 2 side toward the tip, and a neck part 4 smaller in outer diameter than the main thread part 31, without a thread formed, and a tip thread part 5 having a subordinate thread 50 and provided with shape not easily thread-fastened to an internal thread.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw which is prevented from dropping from a female screw. The screw of the present invention is suitable as a terminal screw for attaching an electric terminal or the like.

[0002]

2. Description of the Related Art Generally used screws include a head,
It has a threaded portion protruding forward from the center of one end of the head. This screw is used, for example, as a terminal screw for fixing and holding a lead wire terminal to a mounting base (base) of an electric device or the like. In this case, the screw is previously screwed to the female screw of the mounting base on the production line before use, and forms a sub-assembly with the mounting base.

[0003] Here, when the sub-assembly is transported to the site of use, the screw receives vibration, impact, and the like.
The screw may be loosened by rotating in the screw return direction opposite to the screwing direction when screwed into the female screw, and may fall off from the female screw.
For this reason, the screw is subjected to a so-called tightening operation of screwing the female screw up to the root of the screw portion, so that the screw is prevented from falling off from the female screw due to loosening of the screw.

[0004] Therefore, when fixing and holding the lead wire terminal to the mounting base at the site of use, the screw subjected to the above-mentioned tightening operation is once prepared by a screwdriver once in preparation.
It is necessary to provide a space between the mounting base and the head of the screw where a lead wire terminal can be set, so that the number of working steps is increased.

Therefore, measures are taken to avoid the above-mentioned problems. (1) In the production line, when a screw is screwed into the female screw of the mounting base, the screw is not firmly screwed to the root of the screw portion, but is projected to the other surface side (the outlet side of the female screw) of the mounting base. By caulking the tip of the threaded portion to form a larger diameter portion than the inner diameter of the female screw, or by attaching another part such as a washer to the tip, the screw is prevented from falling off from the female screw, The lead wire terminal is secured with a space between the mounting base and the head of the screw for shipment. By shipping in this state, at the site of use, the lead wire terminal is fixed and held only by setting the lead wire terminal in the space and rotating the screw with the screwdriver without reversely rotating the screw with the screwdriver. In addition, it is possible to prevent the screw from falling off from the female screw due to the screw rotating in the screw return direction and becoming loose due to the influence of vibration, impact, or the like during transportation. (2) Further, as disclosed in Japanese Patent Publication No. 5-1122, a head, a main screw portion projecting forward from the center of one end of the head in order, and an outer diameter smaller than the outer diameter of the main screw portion. There has been proposed a screw having a diameter, a neck portion having no thread, and a tip screw portion.

In this case, in the production line, the tip screw portion is screwed into, for example, the female screw of the mounting base, pulled out to the outlet side of the female screw and protruded, and the neck portion having no thread is fitted into the female screw. In addition to preventing the female screw from dropping off from the female screw, a space is provided between the mounting base and the screw head where a lead wire terminal can be set.

By shipping in this state, at the use site, the lead wire terminal is set in the space, the screw is rotated by the screwdriver, and the main screw is screwed into the female screw without reversely rotating the screw with the screwdriver. The lead wire terminal is fixed and held. In addition, since the female screw is fitted into the neck part where the screw thread is not formed, the screw and the female screw do not screw together, and the female screw is rotated in the screw return direction and loosened due to the influence of vibration, impact, etc. during transportation etc. Can be prevented from falling off.

[0008]

However, in the case of the above-mentioned conventional screws, all have the following disadvantages. (1) In the production line, when mass-producing the sub-assembly, the screw portion is screwed into the female screw of the mounting base, and a crimping operation is performed on a tip portion of the female screw that has come out to the outlet side. Work such as mounting parts must be performed while holding the mounting base, which requires complicated equipment for the process and work to adjust the length of screwing of the screw part into the female screw, etc. It is disadvantageous in manufacturing cost. (2) In the screw disclosed in Japanese Patent Publication No. 5-1122, a tip screw portion is screwed into, for example, a female screw of a mounting base, pulled out to the outlet side of the female screw and projected, and a neck portion having no thread is formed into a female screw. Although the product is shipped with it fitted, if the head of the screw faces downward and is affected by vibration, impact, etc., the tip screw will gradually screw into the female screw and return in the screw return direction. At the worst, falling off and missing.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described conventional problems, and has as its object to provide a screw which can reliably prevent the female screw from falling off and which is advantageous in terms of manufacturing cost.

[0010]

According to a first aspect of the present invention, there is provided a screw comprising a head and a shaft protruding from the center of one end of the head and having a thread on an outer peripheral surface. A main screw part having a main thread on the outer peripheral surface from the head side to the tip, a neck part having an outer diameter smaller than the outer diameter of the main screw part and having no thread, a female screw having a slave thread and And a tip screw portion having a shape that is difficult to be screwed into.

According to a second aspect of the present invention, there is provided the screw according to the first aspect, wherein at least a part of the threaded portion of the distal thread portion is deformed, so that it is difficult to engage with the female thread. Claim 3
In the screw according to claim 2, the deformation is a crushed portion made by crushing at least a part of a thread or a thread valley. The screw according to claim 4 is the screw according to claim 2 or 3, wherein the deformation is only at the neck end of the slave thread.

A screw according to a fifth aspect is the screw according to the second aspect, wherein the deformation is a projection formed by projecting a part of the inclined surface of the slave thread. A screw according to claim 6 is the screw according to claim 2, wherein the deformation is a bent portion formed by bending a part of the helically extending ridge of the slave thread in a direction to decrease the pitch of the slave thread. .

The screw according to claim 7 is the screw according to claim 2, wherein the deformation is an enlarged portion in which the apex angle of the slave thread is widened in a part of the circumferential direction of the slave thread. The screw according to claim 8 is the screw according to claim 7, wherein the enlarged portion has asymmetrical inclination angles of the two inclined surfaces on both sides of the top of the slave thread. According to a ninth aspect of the present invention, in the screw of the second aspect, the deformation is a projection formed by projecting a part of a thread root.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The feature of the screw of the present invention resides in a tip screw portion formed on a shaft portion. The tip screw portion has, for example, a secondary screw thread or a screw valley (trough) which is hardly screwed with a female screw provided on the mounting base. Even if the slave thread or thread valley of the tip screw part has a shape that is difficult to screw with the female screw, the tip screw part is screwed into the female screw entrance (one of the female screw) by the driver engaged with the head of the screw. By forcibly rotating in the screwing direction while pressing against the opening, the screw is screwed and screwed into the female screw.

Then, the screw moves in the screwing direction, and the tip screw portion comes out of the outlet side (the other end side opening) of the female screw. At this time, instead of the tip screw portion, a neck portion without a thread is fitted into the female screw without screwing. As described above, the screw is forcibly screwed into the female screw, forcibly screwed out to the outlet side of the female screw, and brought into a state where the neck is fitted into the female screw, thereby receiving external vibration, impact, or the like. Even if the screw rotates in the screw-back direction opposite to the screw-in direction, the female screw is not engaged with the female screw but merely idle-rotated at the neck unless an action force for forcibly retracting is applied.

Therefore, once the screw is screwed up to the position where the neck fits into the female screw, the tip screw does not engage with the female screw and does not fall off from the female screw. Various configurations described in claims 3 to 8 can be used to make the slave thread of the tip screw portion difficult to screw with the female screw. In addition, "it is difficult to screw with the female screw due to the slave thread or screw thread of the tip screw part" means that the tip screw part can be screwed into the female screw by forcibly screwing the tip screw part by applying a predetermined force or more, Further, it means that the tip screw portion cannot be screwed into the female screw unless an action force for forcibly retracting is applied after the tip screw portion comes out to the outlet side of the female screw by screwing in.

The head is the same as the head of a conventional screw or bolt, and includes a minus screw having a single groove on one end surface thereof, a plus screw having a + -shaped groove, a plus / minus screw including both, and the like. It may be something. Further, the outer peripheral surface of the head, such as a bolt, may be hexagonal, square, or another shape, or may have a regular polygonal concave portion on the upper end surface of the bolt.

The shaft portion is composed of a main screw portion and a neck portion extending from the head toward the distal end, and the above-described distal screw portion which characterizes the screw of the present invention. The main screw portion is a portion corresponding to a conventional screw portion, and at least a thread portion such as a metric screw or an inch screw is formed on an outer peripheral surface portion of the main screw portion near the neck portion side. In addition, the screw portion may be a single-start screw or a multiple-start screw. Further, the shape of the screw thread may be a trapezoidal shape or any other conventionally known thread shape.

The neck is a portion having an outer diameter smaller than the outer diameter including at least the crest of the main screw portion. No thread is formed on the outer peripheral surface of the neck. Note that the neck does not engage with the thread of the internal thread to which the main thread engages. That is, it has an outer diameter smaller than the inner diameter of the screw hole of the female screw. Further, the axial length of the neck portion needs to be set longer than the axial length of the screw hole of the female screw.

[0020]

【Example】

(Embodiment 1) A screw of the present invention, which is applied to a terminal screw for fixing and holding a lead terminal for wiring, will be described with reference to FIGS. Screw 1 of Example 1
As shown in FIG. 1 for the front, FIG. 2 for the bottom, FIG. 3 for the side, and FIG. 4 for the plane, the head 2 and the head 2 are linearly extended in one direction from the head 2 and provided in order. It is composed of a main shaft 3, a neck 4, and a tip screw 5 having a unique shape.

The head 2 has a minus-shaped engaging groove 20a and a plus-shaped engaging groove 20b formed at its upper end for engaging the tip of a driver. The main shaft portion 3 is formed of a columnar shaft portion 30 having one end connected to the head 2 at one end and a main screw portion 31 connected to the neck 4 at the other end. The shaft portion 30 has a length L1 of 2.8 mm and an outer diameter D1 of 3.01 mm to 3.04 mm. Also, the shaft portion 30
The spring washer 300 and the tabbed square washer 301 shown in FIG.

The main screw portion 31 is formed of a generally used M
The length L2 is 3.2 mm at a portion corresponding to the 3.5 screw,
The outer diameter D2 is between 3.01 mm and 3.47 mm and has a main thread 310. The main thread 310 has an apex angle θ1 of 6
0 degree, the pitch P1 is 0.6 mm. The neck 4 has a columnar shape, the other end of which is connected to the tip screw 5, and has a length L.
3 is 1.8 mm, outer diameter D3 is 2.78 mm to 2.82 m
m.

The tip screw portion 5 has a length L4 of 2.2 mm, and has a flat crush portion 52 (formed by flatly crushing a minor thread 50 and a part of the minor thread 50 in a plurality of regions. 1 and 2). The slave thread 50 has an outer diameter D4 of 3.40 mm to 3.42 mm and an apex angle θ2 of 60.
And the pitch P1 is 0.6 mm.

The planar squashed portions 52 are substantially parallel to the axis Y direction of the screw 1 (see FIG. 1), and are spaced 180 ° apart in the circumferential direction S of the slave thread 50 (see FIG. 2). Two crushed areas S2 and S2 set between the non-crushed areas S1 and S1 facing each other at two separated positions. Further, in the planar crushing portion 52, a part of the top portion 51 is deformed and extended in a plate shape along the axis Y direction to form an arc-shaped front end portion 520 and an arc-shaped rear end portion 521 (FIGS. 7, 8, 9). Note that the two planar crushing portions 52, 52 shown in FIG.
The width W between them is 2.23 to 2.27 mm.

The screw 1 of the first embodiment configured as described above
As an example of the use of a lead wire terminal 8 (see FIG.
1) is used as a terminal screw for fixing and holding, prior to its use, a resin mounting base (base) 6 prepared in advance in the production line (see FIG. 5).
And a case where the sub-assembly 9 is configured together with the mounting base 6 will be described.

The mounting base 6 is a thick plate made of resin.
A mounting hole 60 penetrating from the side to the other surface 62 side;
An upright wall 63 extending vertically from one side is formed, and a metal terminal connection base 7 having a female screw 70 is coaxially inserted into and integrated with the mounting hole 60.

The terminal connection base 7 has a thickness of about 1.0 mm.
A female screw 70 formed in the center of the metal plate, and formed on the outer peripheral side at a predetermined distance from the female screw 70. And a connecting terminal 79 projecting toward the other surface 62 of the mounting base 6. The female screw 70 is provided with the M3.
5 has an inside diameter that can be screwed. One surface 75 of the terminal connection base 7 is used as a mounting surface for mounting and contacting the lead wire terminals 8.

Hereinafter, an example of use of the screw 1 of the first embodiment will be described. In the production line, the mounting base 6 to which the screw 1 is to be mounted is previously held at a fixed position by a holding device (not shown). On the other hand, the screw 1 has its axis Y attached to the terminal connecting base 7 of the mounting base 6 by a holding member of a screwing device provided with a driver (not shown).
Of the head 2 are held in a direction coinciding with the center of the
The distal end portion (not shown) of the driver is engaged with either of a and 20b.

The screw 1 is connected to the tip 5 a of the tip thread 5.
Is pressed against the inlet of the female screw 70 from the one surface 75 side of the terminal connection base 7 and is forcibly screwed clockwise. The screw 1 does not engage with the female screw 70 unless the tip screw portion 5 is forcibly screwed into the female screw 70. That is, the planar crushing portions 52 are formed in the tip screw portion 5, and four boundary regions (the a2 portion in FIG. 6) between the crushing regions S2, S2 and the non-crushing regions S1, S1. 8 and 9, the relationship between the flattened portion 52 and the arc-shaped front end portion 52 is shown in FIG.
The 0 and the arc-shaped rear end portion 521 stand upright in parallel with the axis Y direction, and the arc-shaped front end portion 520 strongly presses the inclined surface 74 of the female screw 70 to increase the friction coefficient, so that it is difficult to screw.

The female screw 7 in the non-crushing areas S1, S1 (corresponding to a1 in FIG. 6) of the tip screw portion 5 shown in FIG.
The relationship with 0 is a normal screwing state as shown in a1 of FIG. For this reason, since the slave thread 50 of the non-crushing areas S1 and S1 is not crushed and retains a regular shape, the inclined surface 54 between the top 51 and the valley 53 is formed.
Are in sliding contact with the inclined surface 74 of the female screw 70 and are guided and can be smoothly screwed.

The tip screw portion 5 is screwed into the female screw 70 by the forcible screwing and moves forward, and the rear end 5b comes out to the other surface 76 side of the terminal connecting base 7 and is screwed with the female screw 70. Comes off. Then, in place of the tip screw portion 5, the neck portion 4 of the screw 1 is inserted and fitted into the female screw 70 without being screwed. In this way, the screw 1 is mounted on the mounting base 6 on the production line, and the sub-assembly 9 is
Configured and shipped.

After the sub-assembly 9 is constructed, the screw 1 receives external vibration, impact, or the like under the condition that the head 2 is directed downward as shown in FIG. Even if the screw is rotated in the unscrewing direction, the female screw 70 has the planar crushing portions 52, 52 in which the female screw 70 is difficult to be screwed into the slave thread 50 of the tip screw portion 5.
On the other hand, the front end screw portion 5 does not screw in the screw return direction from the rear end 5b side, and idle rotation occurs at the neck portion 4 where no thread is formed.

In this case, the screw 1 is, for example,
Of the female screw is strongly pressed in the unscrew direction, or the head 2 is strongly pulled in the unscrew direction, and at the same time, the screw is not screwed into the female screw in the direction of falling off unless a force for forcibly rotating in reverse is applied. . Therefore, screw 1 is
To the extent that the subassembly 9 is naturally rotated by an external force such as vibration or impact during transportation of the subassembly 9 or the like, the subassembly 9 only idles and does not fall off from the female screw 70.

Further, according to the screw of the first embodiment, in order to prevent the tip portion from falling off as in the prior art, after the female screw is inserted, the screw is not crimped or a drop-off prevention washer is not attached to the tip portion. There is no need to perform any working process, such as saving, tightening the screw, and returning the screw at the site of use by tightening the screw. For this reason, by using the screw 1 of the first embodiment, it is possible to reduce the number of working steps at the time of configuring the sub-assembly and at the site of use.

At the site of use, the sub-assembly 9
11, the lead wire terminal shown in FIG. 11 is attached to the main shaft 3 of the screw 1 at a distance between one surface 75 of the terminal connection base 7 integrally inserted into the mounting base 6 and the head 2 of the screw 1. After the U-shaped groove 80 of FIG. 8 is inserted, the main screw portion 31 is screwed into the female screw 70 of the mounting base 6, as shown in FIG. Base 7 for terminal connection via square washer 301
Lead terminal 8 between one side 75 of the screw and the head 2 of the screw 1
Can be fixed and held, and electrical connection can be obtained.

After fixing and holding the lead wire terminal 8,
In some cases, it is necessary to remove the lead wire terminal 8. In this case, the tip of the screwdriver is connected to the engagement groove 2 of the head 2 of the screw 1.
By engaging with one of 0a and 20b and rotating counterclockwise in the reverse direction, the fixing and holding can be released and the lead wire terminal 8 can be removed. In addition, the main screw 3
1 and the female screw 70 are disengaged and the neck 4 is fitted into the female screw 70. Therefore, even if the driver is rotated in the reverse direction, the tip screw 5 cannot be screwed into the female screw 70 any more. Since it only rotates idly at the neck 4,
The screw 1 can be reliably prevented from falling off due to excessive turning, and workability is good.

That is, in order to screw the tip screw portion 5 into the female screw 70 from the state where the neck portion 4 is located at the female screw 70, the action force of reverse rotation while pulling the driver in the direction opposite to the pushing direction is required. The screw 1 cannot be screwed because it is necessary, and as a result, the screw 1 can be reliably prevented from falling off. In the screw 1 of the first embodiment, the main shaft 3
Examples of values such as the length of the shaft portion 30, the main screw portion 31, the neck portion 4, and the tip screw portion 5, the outer diameter, the apex angle and pitch of the screw thread, etc. are shown, but are not limited thereto. Instead, the above values can be variously changed according to the purpose. Further, the lead wire terminal 8 fixed and held by using terminal screws may be the lead wire itself, and the terminal connection base 7 may be a nut.

Although the case where the corrugated washer 300 is used has been described, a spring washer (not shown) may be used instead of the corrugated washer 300. (Embodiment 2) A screw 1A of Embodiment 2 shown in FIG.
The configuration is the same as that of the screw 1 of the first embodiment, except that only the screw 1 is provided.

Also in the screw 1A of the second embodiment, even after the sub-assembly 9 is constructed, the screw 1A of the first embodiment is subjected to vibration and impact from the outside and rotated in the unscrewing direction opposite to the screwing direction. Similarly to the case, the tip screw portion 5 is made difficult to be screwed with the female screw 70 by the planar crushing portion 52, so that the following effect can be obtained in addition to the effect of preventing the screw from falling off from the female screw 70. .

That is, in the screw 1A of the second embodiment, when the distal end 5a of the distal end screw portion 5 is screwed into the female screw 70, the planar crushing portions 52, 52 are rear end 5b of the distal end screw portion 5 on the neck 4 side.
Since the screw 5 is formed only on the female screw 70, the tip screw 5 is screwed into the female screw 70 halfway in the direction of the axis Y without any resistance, and is easier to screw than the screw 1 of the first embodiment. The effect of improving workability can be obtained.

(Embodiment 3) The screw 1B of Embodiment 3 shown in FIG. 14 is different from that of Embodiment 1 in that the planar crushing portions 52, 52 are provided on the tip thread portion 5, but on the inclined surface 54 of the slave thread 50. ,
Projection 540 made by projecting a part of it
Is provided. The screw 1B of the third embodiment can be screwed together by forcibly screwing the tip screw portion 5 into the female screw 70 in substantially the same manner as the arc-shaped front end portion 520 of the planar crushing portion 52 of the first embodiment.
After the sub-assembly 9 is constructed, even if it is subjected to vibration, shock, or the like from the outside and rotated in the unscrewing direction opposite to the screwing direction, the tip screw portion 5 becomes the protruding portion 540 as in the case of the screw 1 of the first embodiment. This makes it difficult to engage with the female screw 70, so that an effect of preventing the female screw 70 from falling off can be obtained.

The number of the protrusions 540 is at least one, and a plurality of protrusions 540 can be provided if necessary. (Embodiment 4) A screw 1C of Embodiment 4 shown in FIG. 15 has a ridge line extending spirally of a slave thread 50 instead of providing the planar crushing portions 52, 52 of Embodiment 1 on the tip screw portion 5. The bent portion 510 is formed by bending the top portion 51 forming the portion in a direction to narrow the pitch P2 of the slave thread 50.

The screw 1C of the fourth embodiment can also be screwed into the female screw 70 by forcibly screwing the tip screw portion 5 into the female screw 70 in substantially the same manner as the arc-shaped front end portion 520 of the planar crushing portion 52 of the first embodiment. In addition, after the sub-assembly 9 is constructed, even if it is subjected to vibration or impact from the outside and rotates in the unscrew direction opposite to the screw-in direction, the tip screw portion 5 is bent as in the case of the screw 1 of the first embodiment. Part 51
With 0, the screwing with the female screw 70 is difficult, and the effect of preventing the female screw 70 from falling off can be obtained.

(Fifth Embodiment) A screw 1D of a fifth embodiment shown in FIG. The configuration is such that an enlarged portion 500 that is widened at a part in the circumferential direction S of the slave thread 50 and has a larger angle of 70 degrees than 60 degrees is provided.

The screw 1D of the fifth embodiment can also be screwed into the female screw 70 by forcibly screwing the tip screw portion 5 into the female screw 70 in substantially the same manner as the arc-shaped front end portion 520 of the planar crushing portion 52 of the first embodiment. At the same time, after the sub-assembly 9 is constructed, even if it is subjected to vibration, shock, or the like from the outside and rotates in the screw-back direction opposite to the screw-in direction, the tip screw portion 5 expands as in the case of the screw 1 of the first embodiment. Part 50
With 0, the screwing with the female screw 70 is difficult, and the effect of preventing the female screw 70 from falling off can be obtained.

(Embodiment 6) The screw 1E of Embodiment 6 shown in FIG. 17 is different from the enlarged part 500 of Embodiment 5 in that the two inclined surfaces 540 and 541 on both sides of the top 51 of the slave thread 50 are inclined. This is a configuration in which an asymmetric portion 54e in which the angles θ3 and θ4 are asymmetric is formed. Note that the inclination angles θ3 and θ4 are
A reference line E is a straight line connecting two points 180 degrees apart in the circumferential direction S of the apex 51 of the apex 0 from the apex 51 on the reference line E.
It refers to the angle of inclining back and forth in the direction.

The inclination angle θ3 is the same as the thread 50 of the first embodiment.
Is 30 degrees, which is 1/2 of the apex angle θ2 (60 degrees), and the inclination angle θ4 is 35 degrees larger than the inclination angle θ3 (30 degrees). The screw 1E of the sixth embodiment can be screwed together by forcibly screwing the tip screw portion 5 into the female screw 70 in substantially the same manner as the enlarged portion 500 of the fifth embodiment. Even when the screw 1 is subjected to vibration, shock, or the like, and rotated in the unscrewing direction opposite to the screwing direction, the tip screw portion 5 is in contact with the female screw 70 by the inclined surface 541 of the asymmetric portion 54e as in the case of the screw 1 of the first embodiment. It is possible to obtain an effect that it is difficult to screw together, and that it can be prevented from falling off from the female screw 70.

In the above-described first to sixth embodiments, the case where the screw 1 is applied to a terminal screw for fixing and holding the target lead wire terminal 8 and for making an electrical connection is described as an example. , The screw 1 is for fixing and holding an object between the head of the screw and the end face of the female screw,
It can be applied in the same way as terminal screws. For example, the present invention can be applied to a closing structure of a door of an electronic device housing. In this case,
A nut provided with a female screw is fixed to the housing body side, and the screw 1 of the present application is screwed into the female screw of the nut, so that an object is provided between the head of the screw and the end face of the female screw. The door is closed by holding and fixing and holding a U-shaped cutout provided on the wall of the door.

(Embodiment 7) A screw 1F of an embodiment 7 shown in FIG. And a projection 530 formed by projecting a part of the projection. Also in the screw 1F of the seventh embodiment, the tip screw portion 5 is connected to the female screw 7 in substantially the same manner as the arc-shaped front end portion 520 of the planar crushing portion 52 of the first embodiment.
0 can be screwed together by forcibly screwing the screw 1 into the screw 1 of the first embodiment even if the sub-assembly 9 is subjected to vibration or impact from the outside and is rotated in the unscrewing direction opposite to the screwing direction. As in the case, it is possible to make it difficult for the tip screw portion 5 to be screwed with the female screw 70 by the projection portion 530, so that an effect of preventing the tip screw portion 5 from falling off from the female screw 70 can be obtained.

The number of the protrusions 530 is at least one, and a plurality of protrusions 530 can be provided if necessary.

[0051]

The screw according to the present invention has a head, a main thread portion extending in one direction from the head, a neck, and a shape that is difficult to be screwed into the female screw. ). Even if the slave thread or thread valley of this tip screw part has a shape that is difficult to screw into the female screw, a tool such as a screwdriver is engaged with the head, and the tip of the tip screw part is inserted into the female screw inlet. It can be screwed into the female screw by forcibly pressing and rotating the screw.

Then, the tip screw portion which is forcibly screwed is
Exit to the exit side of the female screw. At this time, the female screw has a neck part where a screw thread with a smaller outer diameter than the tip screw part is not formed,
Instead of the threaded part at the tip, it is inserted and fitted without screwing. In this way, the screw is screwed into the female screw, the female screw passes through the female screw, and escapes.
Even if rotated in the screw return direction opposite to the screwing direction,
The slave screw portion has a shape that is difficult to be screwed into the female screw, so that it does not engage with the female screw but idles at the neck.

Therefore, the screw which is idle in the unscrewing direction can be screwed in such a direction that the slave screw part drops off from the female screw even if it is subjected to vibration, impact or the like, for example, with the head turned downward. Do not match. In this case, the screw, for example, strongly pushes the tip of the tip screw portion in the unscrew direction, or pulls the head strongly in the unscrew direction, and falls off with respect to the female screw unless an action force for forcibly reverse rotation is applied. Do not screw in the direction. For this reason, a screw shortage due to falling off from the female screw does not occur.

Further, the screw is fixed between the head and the end face of the female screw by positioning the neck portion on the female screw.
Since a certain interval at which the object to be held can be set can be ensured, it is not necessary to perform the unscrewing operation as in the past, and the operation of screwing the main thread into the female screw can be performed immediately. The process can be shortened.

[Brief description of the drawings]

FIG. 1 is a front view showing a screw according to a first embodiment.

FIG. 2 is a bottom view of the screw in FIG. 1 as viewed from the distal end side of a distal screw portion.

FIG. 3 is a side view showing a side surface of the screw in FIG. 1;

FIG. 4 is a plan view of the screw in FIG. 3 as viewed from the tip side of the head.

FIG. 5 is a partial cross-sectional view showing a state in which a tip screw portion is screwed to a female screw of an attachment base in the usage example of the screw in FIG.

FIG. 6 is a sectional view taken along the line AA in FIG. 5;

FIG. 7 is an enlarged partial view showing a main part in FIG. 5;

8 is an enlarged cross-sectional view taken along line BB in FIG.

9 is an enlarged cross-sectional view taken along line CC in FIG. 6;

FIG. 10 further tightens the tip screw portion in the state of FIG. 5, pulls out from the other end opening of the female screw, inserts the neck portion into the female screw, and then vibrates under the condition that the head of the screw is downward. And a partial cross-sectional view showing a state in which the distal end screw portion is not screwed into the female screw even when subjected to an impact, which is turned upside down by 180 °.

FIG. 11 is a plan view showing the lead terminal fixed and held to the mounting base by the screw of the first embodiment.

12 is a diagram showing a state in which a lead wire terminal previously set in a mounting space between the head of the screw and one surface of the connection base in the state of FIG. FIG. 6 is a partial cross-sectional view showing a state in which the screw is screwed into and fixed and held between the square washer with the tab and one surface of the connection base.

FIG. 13 is a partial front view showing a main part of the screw according to the second embodiment.

FIG. 14 is a partial front view showing a main part of a screw according to a third embodiment.

FIG. 15 is a partial front view showing a main part of a screw according to a fourth embodiment.

FIG. 16 is a partial front view showing a main part of a screw according to a fifth embodiment.

FIG. 17 is a partial front view showing a main part of a screw according to a sixth embodiment.

FIG. 18 is a partial front view showing a main part of a screw according to a seventh embodiment.

[Explanation of symbols]

 1, 1A, 1B, 1C, 1D, 1E, 1F: Screw 2: Head 3: Shaft 30: Main shaft 31: Main screw 4: Neck 5: Tip screw 50: Secondary screw 51: Top 52 Planar crushing portion 53 valley portion 54 inclined surface S1, S1 non-crushing portion region S2, S2 crushing portion region a1 screw portion between non-crushing portion region and female screw a2 part of crushing portion region and female screw Pressing part with

Continued on the front page (72) Inventor Taisuke Morita 2-10-43 Kami-Osaki, Shinagawa-ku, Tokyo Ho Chiki Co., Ltd. (72) Inventor Satoshi Mori 2- 10-43, Kami-Osaki, Shinagawa-ku, Tokyo Ho Chiki Stock In company

Claims (9)

[Claims] 1. A screw comprising a head and a shaft protruding from the center of one end of the head and having a thread on an outer peripheral surface, wherein the shaft is formed on an outer peripheral surface from the head side toward the tip. A main thread portion having a main thread portion, a neck portion having an outer diameter smaller than the outer diameter of the main thread portion and having no thread, and a shape having a sub thread and hardly screwing with a female screw. A screw having a threaded end. 2. The screw according to claim 1, wherein said tip screw portion is difficult to screw with a female screw because at least a part of the screw portion is deformed. 3. The screw according to claim 2, wherein said deformation is a crushed portion made by crushing at least a part of said slave thread or thread valley. 4. The screw according to claim 2, wherein the deformation is only at an end of the slave thread on the neck side. 5. The protrusion is formed by projecting a part of an inclined surface of the slave thread.
Screws described. 6. The screw according to claim 2, wherein the deformation is a bent portion formed by bending a part of a ridge extending in a spiral shape of the slave thread in a direction to decrease a pitch of the slave thread. 7. The screw according to claim 2, wherein the deformation is an enlarged portion in which a vertex angle of the slave thread is widened in a part of a circumferential direction of the slave thread. 8. The screw according to claim 7, wherein the enlarged portion has asymmetrical inclination angles of two inclined surfaces on both sides of the top of the slave thread. 9. The screw according to claim 2, wherein the deformation is a protrusion formed by projecting a part of a screw root.