JP2018128125A - Screw and screw connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means capable of smoothly discharging chips occurring in screwing a screw into a target member while suppressing increase of a manufacturing cost.SOLUTION: A screw 10 has a shaft part 3 and a head part 5. The shaft part 3 has a tapered tip part 7, and an intermediate part 9 extending from a rear end of the tip part 7 to the head part 5. At the tip part 7, a first thread 11 is provided, and at an intermediate part 9, a second thread 12 is provided. A space S having no thread exists in the rear of a rear end X1 of the first screw 11 in a spiral direction where the first screw 11 extends, and in the front of a tip X2 of the second thread 12 in a spiral direction where the second thread 12 extends. The space S has a width larger than a width of a groove formed by the first thread 11.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a screw and a screw coupling structure. More specifically, the present invention relates to a screw that can more smoothly discharge shavings of a member when the screw is screwed into a target member, and a screw coupling structure configured using the screw.

  Conventionally, a screw 33 can be used to attach the first member 31 to the second member 32 as shown in FIG. In the example of FIG. 1, when the screw 33 is screwed into the first member 31, the inside of the first member 31 is expanded by the tapered tip portion 33 a of the screw 33, and the screw 33 of the tip portion 33 a of the screw 33 is used. The first member 31 is shaved to remove the shavings. As a result, the distal end portion 33 a penetrates the first member 31. The tip 33 a of the screw 33 that has penetrated the first member 31 also penetrates the second member 32. As a result, the thread of the screw 33 engages with the second member 32. By sandwiching the first member 31 and the second member 32 between the thread 33 of the screw 33 engaged with the second member 32 and the head portion 33b of the screw 33, the first member 31 becomes the second member 32. Install.

  The screw 33 used as described above is described in Patent Document 1 below, for example. In Patent Document 1, the first member 31 is a gypsum board, and the second member 32 is a steel plate or a wooden frame member.

JP 2007-315513 A JP 2013-83308 A

  By the way, when the screw 33 is screwed into the first member 31 using a screwdriver (for example, an electric screwdriver or a driver drill), shavings of the first member 31 are generated. The shavings are entangled with the screw 33. In this case, the screw 33 cannot be screwed into the first member 31 smoothly, and it may take time for the screwing, or the screw 33 may be overloaded when screwed. For example, if the screw 33 is attached to the first member 31 in a state in which the screw 33 is excessively loaded, the weight of the first member 31 and the weight of the second member 32 are further applied to the screw 33, so that the screw 33 is In some cases, the first member 31 may be broken due to breakage or the like.

  With respect to such a problem, the structure of the drill screw disclosed in Patent Document 2 includes a blade that cuts shavings at the tip of the screw, and a waste discharging groove that extends from the tip of the screw to the head side of the screw. . Thereby, the shavings are quickly discharged.

  However, in Patent Document 2, since the tip of the screw is provided with both the blade for cutting the shavings and the waste discharging groove instead of the thread, the manufacturing cost of the screw increases accordingly.

  Accordingly, an object of the present invention is to provide means capable of smoothly discharging shavings generated when a screw is screwed into a target member while suppressing manufacturing costs.

To achieve the above object, according to the first invention, a screw having a shaft portion and a head portion,
The shaft portion has a tapered tip portion that is tapered, and an intermediate portion that extends from the rear end of the tip portion to the head portion,
The tip is provided with a first thread, the intermediate part is provided with a second thread,
A space without a thread behind the rear end of the first thread in the spiral direction in which the first thread extends and in front of the tip of the second thread in the spiral direction in which the second thread extends. Exists,
The space is provided with a screw having a width greater than the width of the groove formed by the first thread.

According to the configuration described above, when a screw is screwed into a target member, the member is shaved by the first thread at the tip, and the shavings are guided to the space by the first thread. Since the width of the space is wider than the groove formed by the first thread, the shavings are easily discharged from the space to the outside of the screw.
Moreover, since it is easy to provide the space for smoothly discharging the shavings, the manufacturing cost of the screw can be suppressed.

  The above-mentioned screw is preferably configured as follows.

  The space has a length of one fifth or more around the central axis of the screw.

  According to this configuration, the space is sufficiently long in the spiral direction in which the first screw thread extends, so that shavings are easily discharged from the space to the outside of the screw.

  The intermediate part is provided with a plurality of threads including the second thread.

  According to this configuration, the connection between the screwed member and the screw can be strengthened by the plurality of threads.

  The pitch of the first threads at the tip is greater than the axial spacing between adjacent threads in the intermediate section.

  According to this configuration, since the pitch of the first screw thread is relatively large and rough, when the screw is screwed into the target member, shavings are easily discharged from the tip of the screw, and the screwing of the tip is smooth.

In order to achieve the above object, according to the second invention, a screw having a shaft portion and a head portion,
The shaft portion has a tapered tip portion that is tapered, and an intermediate portion that extends from the rear end of the tip portion to the head portion,
The tip is provided with a first thread, the intermediate part is provided with a second thread,
The first thread extends spirally to a position closer to the head than the tip of the second thread,
The tip of the second thread is located in the middle of the adjacent thread of the first thread in the axial direction of the screw,
In the intermediate portion, a screw is provided in which the height of the second thread is greater than or equal to the height of the first thread.

According to the configuration described above, when a screw is screwed into a target member, the member is shaved by the first thread at the tip, and the shavings are guided to the tip of the second thread by the first thread. . Therefore, when the shavings collide with the tip of the second thread, it is divided or cut, and the moving direction is deviated from the direction along the first thread and the second thread. As a result, the shavings are easily discharged without being entangled with the first screw thread and the second screw thread.
In addition, smooth discharge of the shavings is achieved by the arrangement of the first screw thread and the second screw thread, so that the manufacturing cost of the screw can be suppressed.

According to a third invention, the above-described screw,
A first member through which the screw passes;
A second member coupled to the first member from the screw,
The screw head is located on one side of the first member, and the tip of the screw is located on the other side of the first member;
A screw coupling structure is provided in which the first member and the second member are sandwiched between the engagement portion of the intermediate thread with the second member and the head of the screw.

  According to the configuration described above, the shavings generated when the screw is screwed into the first member are smoothly discharged from the screw without being entangled with the screw by the space or the tip of the second screw thread. As a result, in the screw coupling structure, the load applied to the screw is reduced. Therefore, even if the weight of the first member or the second member whose load is reduced in this way acts on the screw (for example, the head), the first member and the second member by the screw are not damaged without damaging the screw. Can be stably maintained over a long period of time.

  The axial length of the tip of the screw is 0.8 times or more (preferably 1 time or more, more preferably 2 times or more) the thickness of the first member.

  According to this structure, after generating and discharging | emitting large amount of shavings with the 1st thread of the said front-end | tip part, the 2nd thread of the said intermediate part is screwed in to the 1st member. Therefore, the second thread can be smoothly screwed into the first member.

According to the first invention described above, the shavings of the target member to be cut by the first thread when the screw is screwed into the target member is guided to a wide space by the first thread, so that the shavings are It is easy to be smoothly discharged from this space to the outside of the screw.
Moreover, since it is easy to provide a space for smoothly discharging the shavings, the manufacturing cost of the screw can be suppressed.

According to the second invention described above, the shavings of the target member to be cut by the first screw thread when the screw is screwed into the target member are guided to the tip of the second screw thread by the first screw thread. Therefore, the shavings are divided or cut by colliding with the tip of the second screw thread whose height is equal to or higher than the first screw thread, and the moving directions thereof are the first screw thread and the second screw thread. Deviated from the direction along. As a result, the shavings are easily discharged without being entangled with the first screw thread and the second screw thread.
In addition, smooth discharge of the shavings is achieved by the arrangement of the first screw thread and the second screw thread, so that the manufacturing cost of the screw can be suppressed.

  According to the above-described screw coupling structure, the shavings generated when the screw is screwed into the first member is easily entangled with the screw and is smoothly discharged from the screw. As a result, in the screw coupling structure, the load applied to the screw is reduced. Therefore, even if the weight of the first member or the second member whose load is reduced in this way acts on the screw (for example, the head), the first member and the second member by the screw are not damaged without damaging the screw. Can be stably maintained over a long period of time.

It is an example which shows the combined state of the 1st member and 2nd member by a screw. 1 shows a screw according to a first embodiment of the present invention. It is the schematic which shows each screw thread in the screw of FIG. It is the elements on larger scale of FIG. 1, and shows the space provided in the screw. 3 shows a screw according to a second embodiment of the present invention. It is the elements on larger scale of FIG. 5, and shows the height of each screw thread. The screw coupling structure using the screw by 1st Embodiment or 2nd Embodiment is shown.

  A preferred embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

[First Embodiment]
FIG. 2 shows a screw 10 according to a first embodiment of the present invention. FIG. 2A is a side view of the screw 10. FIG. 2B shows a case where the screw 10 of FIG. 2A is viewed from the back side of the paper surface of FIG. FIG. 2C is a CC arrow view of FIG. The screw 10 has a shaft portion 3 and a head portion 5. The shaft portion 3 includes a tapered tip portion 7 that is tapered and an intermediate portion 9 that extends from the rear end of the tip portion 7 to the head portion 5 in the axial direction of the screw 10 (hereinafter simply referred to as the axial direction). Have.

  The tip of the tip 7 is preferably sharp. A first screw thread 11 extending in a spiral shape is formed at the distal end portion 7. Preferably, the tip of the first screw thread 11 extends to the tip of the tip portion 7, and when the screw 10 is started to be screwed into the target member, the tip of the first screw thread 11 hits the target member. It bites into the member. In the example of FIG. 2B, the rear end X1 of the first thread 11 is located in the vicinity of the boundary between the intermediate portion 9 and the distal end portion 7 in the intermediate portion 9. FIG. 3 is a schematic diagram illustrating the screw threads 11, 12, and 13 provided on the screw 10 with a single line extending in the spiral direction for the sake of simplicity.

  The intermediate part 9 is integrated with the head part 5 and the tip part 7. The intermediate part 9 is preferably cylindrical. The intermediate portion 9 is provided with a plurality of threads including the second thread 12. In the example of FIG. 2, the plurality of threads includes a second thread 12 and a third thread 13 that extend in a spiral shape. However, a plurality of three or more threads including the second thread 12 may be provided in the intermediate portion 9, and only the second thread 12 (that is, one thread) as the thread. May be provided in the intermediate portion 9. In the example of FIG. 2, the tip X2 of the second screw thread 12 and the tip X3 of the third screw thread 13 are located in the vicinity of the boundary between the intermediate part 9 and the tip part 7 in the intermediate part 9. Further, the second screw thread 12 and the third screw thread 13 extend spirally from the tips X2 and X3 to the respective rear ends located in the vicinity of the head 5.

  FIG. 4 is a partially enlarged view of FIG. As shown in FIG. 4, according to the first embodiment, the spiral extending behind the rear end X <b> 1 of the first thread 11 and extending the second thread 12 in the spiral direction in which the first thread 11 extends. In the direction, there is a non-threaded space S in front of the tip X2 of the second thread 12 (see FIG. 2A). Further, the space S has an axial width W2 that is larger than the axial width W1 of the groove formed by the first thread 11.

  Preferably, the space S has a length equal to or greater than one fifth of the circumference (more preferably, one quarter of the circumference) around the central axis of the screw 10. In the example of FIG. 4, in the circumferential direction around the central axis of the screw 10 (hereinafter simply referred to as the circumferential direction), the space S is a third distance from the end of the space S where the rear end X1 of the first thread 11 is located. It extends to the end of the space S where the tip X3 of the screw thread 13 is located. In the case where only the second thread 12 is provided as the thread in the intermediate portion 9, the space S is the second from the edge of the space S where the rear end X1 of the first thread 11 is located in the circumferential direction. It extends to the end of the space S where the tip X2 of the screw thread 12 is located.

The pitch Pa of the first thread 11 is preferably in the range of 2 mm to 4 mm, more preferably in the range of 2 mm to 3 mm (for example, about 2.5 mm). The total length of the screw 10 may be a value within a range of 25 to 60 mm (for example, 35 mm).
Further, the pitch Pa of the first screw threads 11 is larger than the axial interval Pb between the screw threads adjacent to each other in the intermediate portion 9 (in FIG. 4, the second screw threads 12 and the third screw threads 13). The axial interval Pb is an interval between adjacent screw threads, and is constant over a range where the screw threads are provided in the intermediate portion 9. In the example of FIG. 4, the pitch of the second thread 12 and the pitch of the third thread 13 is twice Pb and is the same as the pitch Pa of the first thread 11 (that is, 2Pb = Pa). ). In the case where only the second thread 12 is provided as a thread on the intermediate portion 9, the pitch of the first thread 11 is preferably larger than the pitch of the second thread 12.

  The head portion 5 is coupled to the rear end of the shaft portion 3. The area of the head 5 seen from the axial direction (that is, the area of the outer surface of the head 5 shown in FIG. 2C) is at least twice the area of the cross section of the axial part 3 by a plane orthogonal to the axial direction ( In an example, it is 2.25 times). In addition, a recess 15 is formed on the outer surface of the head 5 to engage the tip of a screwdriver (for example, an electric screwdriver or a driver drill) for turning the screw 10. In FIG. 2C, the depression 15 has a cross shape.

(Effect by 1st Embodiment)
In the first embodiment, when the screw 10 is screwed into the target member, the target member (for example, gypsum board) formed of gypsum or wood, for example, is shaved by the first screw thread 11 of the tip 7, The shavings are guided to the space S by the first thread 11. Since the width W <b> 2 of the space S is wider than the width W <b> 1 of the groove formed by the first thread 11, the shavings are easily discharged from the space S to the outside of the screw 10. Accordingly, it is possible to reduce the shavings that enter the thread groove by the thread of the intermediate portion 9 and become entangled. As a result, the load applied to the screw 10 when the screw 10 is screwed into the target member can be reduced, and the screw 10 can be smoothly screwed into the target member.

  Moreover, since it is easy to provide the space S for smoothly discharging the shavings, the manufacturing cost of the screw 10 can be suppressed.

  Since the space S is sufficiently long in the spiral direction in which the first thread 11 extends, shavings are easily discharged from the space S to the outside of the screw 10 without being hindered by the thread.

  Since a plurality of threads including the first thread 11 and the second thread 12 are formed in the intermediate portion 9, the connection between the member into which the screw 10 is screwed and the screw 10 is coupled. Can be strengthened.

  Since the pitch of the first thread 11 is larger than the axial interval between adjacent threads in the intermediate portion 9, that is, the pitch of the first thread 11 is relatively large and rough, the screw 10 is the target member. When screwing in, the shavings are easily discharged from the tip portion 7, and the screwing of the tip portion 7 becomes smooth.

[Second Embodiment]
FIG. 5 shows a screw 10 according to a second embodiment of the invention. FIG. 5A is a side view of the screw 10. FIG. 5B shows a case where the screw 10 of FIG. 5A is viewed from the back side of the paper surface of FIG. FIG. 5C is a CC arrow view of FIG. The screw 10 according to the second embodiment differs from the screw 10 according to the first embodiment in the points described below. The screw 10 according to the second embodiment is the same as the screw 10 according to the first embodiment in that it is not described below.

In the second embodiment, similarly to the first embodiment, the distal end portion 7 is provided with a first thread 11 and the intermediate portion 9 is provided with a second thread 12.
In this regard, in the second embodiment, the first thread 11 extends spirally to the rear end X1 at a position closer to the head 5 than the tip X2 of the second thread 12. In the example of FIG. 5, in the intermediate portion 9, the first thread 11 and the second thread 12 constitute two threads. In the intermediate portion 9, three or more threads including the first thread 11 and the second thread 12 may be configured.

  FIG. 6 is a partially enlarged view of FIG. 5A, and shows the vicinity of the tip X <b> 2 of the second screw thread 12. The tip X2 of the second thread 12 is located in the middle (preferably the center) of the adjacent ridges 11a of the first thread 11 in the axial direction.

  In the intermediate portion 9, the height H2 of the second thread 12 is the same as the height H1 of the first thread 11 or is greater than the height H1. The height of the second thread 12 increases from zero to the above-described height H2 until the circumferential position of the second thread 12 moves from the tip X2 by a distance within a quarter of the circumference of the center axis of the screw 10. Thereafter, while maintaining a constant height H2, it extends in the spiral direction to the vicinity of its rear end. The first screw thread 11 extends in the spiral direction to the vicinity of the rear end X1 while maintaining a constant height H1 over the entire intermediate portion 9 except for the vicinity of the rear end X1.

  In FIG. 6, the tip 12 a of the second thread 12 forms a blade 17. The distal end portion 12a is a portion from the distal end X2 of the second thread 12 to the height H2. The blade 17 is a portion surrounded by a broken line in FIG. 6 and is a radially outward end of the distal end portion 12a. Here, the radial direction means the radial direction of the screw 10. That is, the radial direction is a direction orthogonal to the central axis of the screw 10 and is a direction extending radially from the central axis. The blade 17 may be rounded to some extent in order to make the handling of the screw 10 safe.

(Effect by 2nd Embodiment)
When the screw 10 is screwed into the target member, the target member is shaved by the first thread 11 of the tip 7, and the shavings are guided to the tip of the second thread 12 by the first thread 11. . Accordingly, the shavings are divided or cut by colliding with the tip 12a of the second screw thread 12 whose height is equal to or higher than the first screw thread 11, and the moving direction thereof is the same as that of the first screw thread 11. Deviated from the direction along the second thread 12. As a result, the shavings are easily discharged without being entangled with the first screw thread 11 and the second screw thread 12. Accordingly, it is possible to reduce the shavings that enter the thread groove by the thread of the intermediate portion 9 and become entangled. As a result, the load applied to the screw 10 when the screw 10 is screwed into the target member can be reduced, and the screw 10 can be smoothly screwed into the target member.

  Moreover, since it is achieved by arrangement | positioning of the 1st thread 11 and the 2nd thread 12 to discharge | emit shavings smoothly, the manufacturing cost of the screw 10 can be held down.

  Since a plurality of threads including the first thread 11 and the second thread 12 are formed in the intermediate portion 9, the connection between the member into which the screw 10 is screwed and the screw 10 is coupled. Can be strengthened.

  Since the pitch Pa of the first thread 11 at the tip 7 of the screw 10 is larger and coarser than the axial interval between adjacent threads in the intermediate part 9, when the screw 10 is screwed into the target member, the shavings are at the tip. It is easy to be discharged from the part 7, and the screwing of the tip part 7 becomes smooth.

  The shavings can be divided or cut by the blade 17 of the tip 12a of the second thread 12. Therefore, since the shavings become fine, the shavings can be discharged from the screw 10 more smoothly.

[Screw connection structure]
FIG. 7 shows a screw coupling structure 20 using the screw 10 according to the first embodiment or the second embodiment described above. The screw coupling structure 20 includes a screw 10 according to the first embodiment or the second embodiment (hereinafter simply referred to as a screw 10), a first member 21 through which the screw 10 passes, and a first member 21 than the screw 10. And a second member 22 coupled to the.

  In one embodiment, the first member 21 is a gypsum member (eg, gypsum board) formed of gypsum, and the second member 22 is a metal or wooden thin plate. However, according to the present invention, the first member 21 is not limited to a gypsum member, and may be a member formed of another substance (for example, wood) that generates shavings when the screw 10 is screwed.

The screw coupling structure 20 is formed by the following procedure.
(1) The back surface 21 a of the first member 21 is brought into contact with the front surface 22 a of the second member 22. (2) The screw 10 is screwed from the surface 21b on one side of the first member 21 using a screwdriver (for example, an electric screwdriver or a driver drill) while maintaining the state of (1) above. As a result, the screw 10 passes through the first member 21 and the second member 22, and the thread in the intermediate portion 9 of the screw 10 engages with the second member 22. In this state, the first member 21 and the second member 22 are preferably sandwiched between the engaging portion 23 engaged with the second member 22 and the head 5 at the thread of the intermediate portion 9.

  In the screw coupling structure 20, the head 5 of the screw 10 is located on one side of the first member 21, and the tip portion 7 of the screw 10 is located on the other side of the first member 21. Further, the first member 21 and the second member 22 are sandwiched between the engagement portion 23 of the screw thread of the intermediate portion 9 with the second member 22 and the head portion 5 of the screw 10.

  The axial length of the tip 7 of the screw 10 is preferably 0.8 times or more (preferably 1 time or more, more preferably 2 times or more) the thickness of the first member 21.

In one embodiment, the first member 21 is a gypsum board having a thickness in the left-right direction of FIG. 7, and the second member 22 is a thin metal plate having a thickness in the left-right direction of FIG. In this case, for example, the thickness of the gypsum board 21 is a value within a range of 10 mm to 15 mm (for example, 12.5 mm), and the thickness of the thin plate 22 is a value within a range of 0.5 mm to 1.5 mm (for example, About 0.8 mm). The thin plate 22 may cover a wide area (for example, the entire surface) of the back surface 21a of the gypsum board 21 or may be “a thin steel plate frame material having a substantially C-shaped cross section” described in Patent Document 1. There may be. In such an embodiment, the total length of the screw 10 is, for example, a value within a range of 25 to 60 mm (for example, 35 mm), and the outer diameter (diameter) of the intermediate portion 9 of the screw 10 may be about 5 mm. The axial length of the tip 7 may be about 10 mm.
However, the present invention is not limited to such an embodiment, and the dimensions of the screw 10, the first member 21, and the second member 22 may be appropriately set so that the effects of the present invention can be obtained.

  In FIG. 7, only one screw 10 is shown, but in practice, there are a large number of screws 10 in the same state as the screw 10 shown in FIG. That is, a large number of screws 10 penetrate the first member 21 and the second member 22 like the screw 10 of FIG. 7, and the first member 21 and the second member 22 are coupled by these screws 10. .

(Effects of screw connection structure)
In the above-described procedure (2), when the screw 10 is screwed from the surface 21b on one side of the first member 21, shavings are generated from the first member 21 by the first thread 11 of the tip 7 and as described above. In addition, the shavings are smoothly discharged from the screw 10. Therefore, it becomes difficult for the shavings to be entangled with the screw 10, and as a result, the load applied to the screw 10 is reduced.

  Moreover, in (2) of the above-mentioned procedure, since shavings are discharged | emitted smoothly from the screw 10, it is suppressed that shavings enter into the thread groove by the thread of the intermediate part 9. FIG. As a result, it is prevented that the engagement between the thread of the intermediate part 9 and the second member 22 is weakened by the shavings that have entered the thread groove by the thread of the intermediate part 9.

  Therefore, in the screw coupling structure 20, the load applied to the screw 10 by shavings is reduced, and the engagement between the thread of the intermediate portion 9 and the second member 22 can be strongly maintained. Therefore, even if the weight of the first member 21 or the second member 22 acts on the screw 10 (for example, the head 5), the first member 21 and the second member 22 formed by the screw 10 are not damaged without damaging the screw 10. The bonded state can be stably maintained over a long period of time.

  The area of the head 5 (that is, the area of the outer surface of the head 5 shown in FIG. 2C) is more than twice the area of the cross section of the shaft portion 3 by a plane orthogonal to the axial direction (in one example, 2.25). Therefore, the first member 21 can be stably pressed by the head 5. Therefore, the first member 21 is prevented from falling off from the head 5 of the screw 10.

The present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention. For example, the following modified example may be adopted. In this modified example, the points not described below are the same as described above.
(Example of change)
For example, a cutting blade may be provided at the tip of the screw 10 in the first embodiment or the second embodiment. In this case, the tip of the first thread 11 may extend to, for example, the position of the cutting blade or the vicinity of the position. In this case, the total length of the screw 10 may be a value within the same range as described above, but is 40 mm in one example.

3 shaft part, 5 head part, 7 tip part, 9 middle part, 10 screw, 11 first thread, 11a thread, 12 second thread, 12a tip part of second thread, 13 third thread, 15 recesses, 17 blades, 20 screw connection structure, 21 first member (gypsum board), 22 second member (thin plate), 23 engaging portion, 31 first member, 32 second member, 33 screw, 33a tip, 33b Head, S space, W1 groove width by first thread, W2 space width, X1 rear end of first thread, X2 second thread end, X3 third thread end

Claims (7)

A screw having a shaft and a head,
The shaft portion has a tapered tip portion that is tapered, and an intermediate portion that extends from the rear end of the tip portion to the head portion,
The tip is provided with a first thread, the intermediate part is provided with a second thread,
A space without a thread behind the rear end of the first thread in the spiral direction in which the first thread extends and in front of the tip of the second thread in the spiral direction in which the second thread extends. Exists,
The space, wherein the space has a width greater than the width of the groove formed by the first thread.   The screw according to claim 1, wherein the space has a length of one fifth or more around the central axis of the screw.   The screw according to claim 1 or 2, wherein the intermediate portion is provided with a plurality of threads including a second thread.   4. The screw according to claim 1, wherein a pitch of the first screw threads at the tip portion is larger than an axial interval between adjacent threads at the intermediate portion. A screw having a shaft and a head,
The shaft portion has a tapered tip portion that is tapered, and an intermediate portion that extends from the rear end of the tip portion to the head portion,
The tip is provided with a first thread, the intermediate part is provided with a second thread,
The first thread extends spirally to a position closer to the head than the tip of the second thread,
The tip of the second thread is located in the middle of the adjacent thread of the first thread in the axial direction of the screw;
In the intermediate portion, the height of the second thread is equal to or higher than the height of the first thread. The screw according to any one of claims 1 to 5,
A first member through which the screw passes;
A second member coupled to the first member from the screw,
The screw head is located on one side of the first member, and the tip of the screw is located on the other side of the first member;
A screw coupling structure in which a first member and a second member are sandwiched between an engagement portion with a second member in a thread of the intermediate portion and a head portion of the screw.   The screw coupling structure according to claim 6, wherein an axial length of the tip portion of the screw is 0.8 times or more a thickness of the first member.

Images