JP6967769B2 - Screw - Google Patents

Description

The present invention relates to screws that can be used as a metal substrate.

Conventional screws are described in, for example, Patent Document 1. The screws described in the same document can be screwed into a metal substrate and fixed.

Japanese Unexamined Patent Publication No. 9-302783

However, in the conventional technique, when the screw is screwed into the metal base, the metal base is scraped to generate fine chips, and the generated fine chips are easily scattered around the metal base.

In view of the above circumstances, an object of the present invention is to provide a screw capable of suppressing the scattering of fine chips.

The screw of the present invention is
It is a screw that can be screwed into a metal base and fixed.
A resin layer made of a thermoplastic material that wraps at least the tip of the shaft and is solid at room temperature and is melted by frictional heat when the shaft is screwed into the metal base is provided .
The thickness of the resin layer is larger in the vicinity of the most advanced portion of the shaft portion than in other portions .

According to the present invention, the resin layer made of a thermoplastic material is melted by utilizing the frictional heat generated between the metal base and the shaft portion when the screw is screwed into the metal base, and the metal base is scraped by the molten resin. The generated fine chips can be caught and adsorbed. The molten resin containing chips resolidifies at room temperature to form a mixed solid of resin and chips, but a part of the mixed solid adheres to the joint where the metal base and the shaft are joined. Since it remains in the remaining state, the amount of chips scattered away from the metal substrate can be reduced. Further, even if the mixed solid matter is scraped away from the metal base by screwing in the screw, the shavings are larger than the normal chips, so that they are less likely to scatter than the normal chips. Therefore, according to the present invention, it is possible to suppress the scattering of fine chips.
Further, as an incidental effect of the present invention, the mixed solid matter fixed to the joint portion where the metal base and the shaft portion are joined suppresses the wobbling of the screw with respect to the metal base, and makes it difficult for the screw to loosen. Further, since the resin layer is solid at room temperature, it becomes a screw that does not impair the handleability such as portability.
Further, according to this configuration, a large amount of chips are generated in the vicinity of the most advanced portion of the shaft portion at the start of screwing the screw into the metal substrate. Correspondingly, by thickening the resin layer in the vicinity of the most advanced portion of the shaft portion, it becomes possible to suitably adsorb the chips generated at the start of screwing to the molten resin.

In the present invention
It is preferable that the sharp portion at the tip of the shaft portion is exposed without being covered with the resin layer.

According to this configuration, it is possible to insert a sharp portion into a metal substrate and hook it. Therefore, as compared with the case where the sharp portion at the tip of the shaft portion is covered with a resin layer, for example, with respect to the metal substrate. The misalignment of the shaft portion is less likely to occur.

In the present invention
It is preferable that the lead angle of the screw portion in the shaft portion is smaller than the lead angle of the coarse screw.

According to this configuration, since the lead angle of the threaded portion is smaller than that of the coarse thread, the threaded portion is screwed with respect to the rotation amount of the shaft portion as compared with the threaded portion having the coarse thread. The amount can be kept small. As a result, the amount of rotation of the shaft portion required to fix the shaft portion to the metal base increases, and it becomes possible to generate sufficient frictional heat between the screw portion of the shaft portion and the metal base portion, and the screw portion of the screw portion can be generated. The nearby resin layer is suitably melted, and chips are easily adsorbed on the molten resin.

It is the whole view of the screw which shows the resin layer in a half cross section. It is a vertical sectional view of the waterproof roof structure using a screw. It is a figure which shows the state at the time of the start of screwing of a screw with respect to a metal base. It is a figure which shows the state in the process of screwing a screw into a metal base. It is a figure which shows the state at the time of completion of screwing of a screw with respect to a metal base. It is a figure which shows the screw in another embodiment.

Hereinafter, embodiments that are an example of the present invention will be described with reference to the drawings.
[About the structure of the screw]
The screw 1 shown in FIG. 1 and the like can be fixed by being screwed into a metal base. The screw 1 includes a head portion 3 having, for example, a square hole engaging portion 2 capable of engaging a tool such as an impact driver, and a shaft portion 4 connected to and integrated with the head portion 3. , A resin layer 5 that wraps at least the tip portion of the shaft portion 4 is provided. The head portion 3 and the shaft portion 4 of the screw 1 are made of metal.

The screw 1 uses a tool to push the head portion 3 toward the metal base, so that the shaft portion 4 is screwed into the metal base in the axial direction X and screwed, and the shaft portion 4 is fixed to the metal base. It is possible.

The shaft portion 4 has a threadless portion 6 that is not threaded and a threaded portion 7 that is threaded. That is, the screw 1 is a half-screw type. Further, a drill-shaped cutting edge 8 is provided on the tip end side of the shaft portion 4 with respect to the screw portion 7 as a cutting portion capable of cutting a metal base by pushing rotation of the shaft portion 4.

The lead angle θ of the screw portion 7 in the shaft portion 4 is smaller than the lead angle of the coarse screw. To add an explanation, the screw portion 7 is a fine screw. The fine screw has a smaller pitch P between the threads as compared with the coarse screw having the same nominal diameter. For the standard dimensions of the coarse screw, for example, JIS standard number B0205-1982 can be referred to. Further, for the reference dimension of the fine screw, for example, JIS standard number B0207-1982 can be referred to.

The resin layer 5 is a solid at room temperature and is made of a thermoplastic material that melts due to frictional heat when the shaft portion 4 is screwed into a metal base.

As the thermoplastic material constituting the resin layer 5, a material used as a hot melt adhesive can be used. As the main component of the thermoplastic material, various thermoplastic resins such as an ethylene-vinyl acetate copolymer resin, a polyester resin, and a modified olefin resin can be used. Further, the thermoplastic material may be a mixture of a plurality of types of thermoplastic resins or may contain a substance other than the thermoplastic resin.

The melting point of the resin layer 5 varies depending on the type of the thermoplastic resin as the main component, but is preferably a temperature between about 60 ° C. and 100 ° C. That is, the resin layer 5 is solid at room temperature and is rapidly melted by the frictional heat when the screw 1 is screwed into the metal base.

The resin layer 5 is provided over the tip end side portion of the screw portion 7 and the cutting edge 8. The resin layer 5 covers the entire circumference of the threaded portion 7 and the cutting edge 8. The outer diameter of the resin layer 5 is larger than the outer diameter of the thread of the screw portion 7.

The thickness of the resin layer 5 is larger in the vicinity of the cutting edge 8 which is the most advanced portion of the shaft portion 4 than in other portions such as the screw portion 7. The sharpened portion 9 of the cutting edge 8 located at the most advanced portion of the shaft portion 4 is exposed without being covered by the resin layer 5.

[Application of screws to waterproof roof structure]
The above-mentioned screw 1 can be suitably used, for example, in a waterproof roof structure having heat insulating properties on the roof of a building. The metal base in the waterproof roof structure is a deck plate 10 made of a steel plate, which is a metal plate base having an uneven cross section. The deck plate 10 is a member having strength that can also be used as a flooring material. The deck plate 10 has fire resistance.

In the waterproof roof structure, the deck plates 10 are arranged side by side on the beam-shaped structural frame 12. A heat insulating material 13 made of a porous material is laid on the upper part of the deck plate 10. Above the deck plate 10, conductive disc plates 14 are arranged at predetermined pitch intervals above the heat insulating material 13. The screw 1 is passed through the heat insulating material 13 and the deck plate 10 through the hole 15 of the disc plate 14, and is screwed into and fixed to the deck plate 10. The disc plate 14 and the heat insulating material 13 are sandwiched between the head portion 3 of the screw 1 and the joint portion 20 between the deck plate 10 and the screw 1. A waterproof sheet 16 is laid on the upper part of each disc plate 14. The waterproof sheet 16 and the disc plate 14 are surface-bonded and fixed to each other by welding using an induction heating device. As a result, in the waterproof roof structure, the heat insulating material 13 and the waterproof sheet 16 are fixed to the deck plate 10 which is a metal base via the screw 1.

[About fixing screws to the deck plate]
The fixing of the screw 1 to the deck plate 10 will be described with reference to FIGS. 2 to 5. In FIGS. 3 to 5, the heat insulating material 13 in FIG. 2 is not shown.

First, as shown in FIG. 3, when screwing the screw 1 into the deck plate 10 is started, the sharp portion 9 of the cutting edge 8 located at the tip of the shaft portion 4 of the screw 1 is ridged on the deck plate 10. With the screw 1 pressed against the upper surface of the portion, the screw 1 is pushed in and rotated by a tool to position the screw 1 with respect to the deck plate 10. At this time, since the sharpened portion 9 is exposed without being covered with the resin layer 5, it is easy to position the shaft portion 4 with respect to the deck plate 10.

Next, as shown in FIG. 4, the screw 1 is further pushed in and rotated by a tool, and the shaft portion 4 is screwed into the deck plate 10 while cutting the deck plate 10 with the cutting edge 8. At this time, the frictional heat generated between the cutting edge 8 of the shaft portion 4 of the screw 1 and the deck plate 10 is transferred from the shaft portion 4 to the resin layer 5, and the frictional heat melts the resin layer 5 and flows. The molten resin 18 has properties and adhesiveness. At the same time, the deck plate 10 is cut by the cutting edge 8 to generate fine chips 17. The fine chips 17 are caught in the molten resin 18 and adsorbed. At this time, since the thickness of the resin layer 5 is large in the vicinity of the cutting edge 8 which is the most advanced portion of the shaft portion 4, a sufficient amount of molten resin 18 is generated in the vicinity of the cutting edge 8 and melted. The chips 17 are sufficiently adsorbed by the resin 18.

Then, when the screwing of the shaft portion 4 with respect to the deck plate 10 is advanced, the cutting edge 8 of the shaft portion 4 penetrates the deck plate 10 and the screw portion 7 reaches the deck plate 10. At this time, the lead angle θ of the screw portion 7 in the shaft portion 4 is smaller than the lead angle of the coarse screw. As a result, in the threaded portion 7, the screwing speed of the shaft portion 4 with respect to the deck plate 10 becomes slower, and the threaded portion 7 is not screwed so much into the deck plate 10, and between the threaded portion 7 and the deck plate 10. It is possible to generate a large amount of frictional heat. That is, the amount of rotation of the shaft portion 4 required for fixing the shaft portion 4 to the deck plate 10 increases, and it becomes possible to generate sufficient frictional heat between the screw portion 7 and the deck plate 10. As a result, the resin layer 5 in the vicinity of the screw portion 7 can be quickly melted. It should be noted that approximately one pitch P of the screw portion 7 corresponds to the plate thickness of the deck plate 10. At this time, since the molten resin 18 in which the chips 17 are involved has viscosity, it is more likely to be discharged above the deck plate 10 through the screw portion 7 than in the case of only the normal chips 17.

As shown in FIG. 5, when the screwing of the shaft portion 4 is stopped, the screw portion 7 of the screw 1 is fixed to the screw hole portion 11 formed in the deck plate 10 by the shaft portion 4. The molten resin 18 containing the chips 17 is cooled to room temperature over time and resolidified to become a mixed solid 19. A part of the mixed solid material 19 remains fixed to the upper surface of the deck plate 10, the lower surface of the deck plate 10, between the joint portion 20 between the shaft portion 4 and the deck plate 10, and the like. Further, since the mixed solid 19 is larger than ordinary chips, it is difficult for the mixed solid 19 to scatter below the deck plate 10.

Further, as shown in FIG. 2, when the screw 1 is screwed into and fixed to the deck plate 10, the molten resin 18 closes the screw hole portion 11 formed in the deck plate 10 without a gap and resolidifies in that state. Becomes a mixed solid 19. As a result, for example, even if the waterproof sheet 16 is torn or the like, water is stopped by the mixed solid 19 in the screw hole portion 11, so that rainwater or the like leaks below the deck plate 10 through the screw hole portion 11. Can be suitably prevented.

[About repair work of waterproof roof structure]
The screw 1 provided with such a resin layer 5 is repaired to the above-mentioned waterproof roof structure by using the existing deck plate 10 as it is, especially when the waterproof sheet 16 or the like on the deck plate 10 is deteriorated. It can be suitably used when

By using the screw 1 provided with the resin layer 5 described above, it becomes difficult for the fine chips 17 to fall below the deck plate 10, so that the metal members such as the structural skeleton 12 located below the deck plate 10 are finely divided. It is possible to prevent the small chips 17 from adhering to and inducing corrosion such as rust.

Then, for example, even when the ceiling is not attached to the building and the living space is directly under the deck plate 10, by using the screw 1 provided with the resin layer 5, the deck plate 10 can be used. It is possible to prevent the fine chips 17 from falling into the living space located below and being scattered in the living space. This makes it possible to omit the process of laying a curing sheet for receiving the chips 17 under the deck plate 10 at the time of repair work.

Further, for example, even when the building is a hut or the like and the ceiling is attached below the deck plate 10, by using the screw 1 provided with the resin layer 5, the ceiling can be used. It becomes difficult for fine chips 17 to accumulate in the ceiling. As a result, it is possible to prevent fine chips 17 from adhering to the metal member arranged in the pocket of the ceiling and inducing corrosion such as rust.

As described above, by using the screw 1 provided with the resin layer 5 as described above, fine chips are less likely to be scattered, so that it is possible to carry out repair work having excellent workability with less man-hours and construction cost.

[Another Embodiment]
Hereinafter, another embodiment in which the above embodiment is modified will be illustrated. The following alternative embodiments may be applied to the above embodiment in combination as long as there is no contradiction. The scope of the present invention is not limited to the contents of each embodiment.

(1) In the above embodiment, the resin layer 5 is provided only on the tip end side portion of the screw portion 7, but the present invention is not limited to this. For example, the resin layer 5 may be provided on the entire portion of the screw portion 7.

(2) In the above embodiment, the resin layer 5 is provided over the threaded portion 7 and the cutting edge 8, but the present invention is not limited to this. For example, the resin layer 5 may be provided only on the cutting edge 8.

(3) In the above embodiment, the pointed portion 9 at the tip of the shaft portion 4 is not covered by the resin layer 5 and is exposed, but the present invention is not limited to this. For example, the pointed portion 9 at the tip of the shaft portion 4 may also be covered with the resin layer 5.

(4) In the above embodiment, the tip of the shaft portion 4 of the screw 1 has a drill-shaped cutting edge 8 as a cutting portion, but the present invention is not limited to this. For example, as shown in FIG. 6, the tip end portion of the shaft portion 4 of the screw 1 may be a winding tip 21 in which a conical thread is cut as a cutting portion. Further, when the deck plate 10 is provided with a pilot hole, a screw 1 having no sharp tip at the tip of the shaft portion 4 may be used.

(5) In the above embodiment, the resin layer 5 is thickened at the tip of the shaft portion 4, but the present invention is not limited to this. For example, the thickness of the resin layer 5 may be uniform over the entire area of the shaft portion 4.

(6) In the above embodiment, the screw portion 7 is an example of a fine screw having a lead angle θ and a pitch P smaller than that of a coarse screw when compared with the same nominal diameter. Not limited to. The screw portion 7 may be a fine screw having a smaller lead angle and pitch than the fine screw. On the other hand, the lead angle θ of the screw portion 7 may be the same as the lead angle of the coarse screw. That is, the screw portion 7 may be a coarse screw.

(7) In the above embodiment, the half-screw type screw 1 having the screwless portion 6 is exemplified, but the present invention is not limited to this, and a full-screw type screw having no screwless portion 6 may be used.

(8) In the above embodiment, the deck plate 10 is exemplified as the metal base, but the present invention is not limited to this. For example, the metal base may be a metal plate base such as a folded plate member or a tile bar roof member. Further, the metal base may have a thickness that allows it to be screwed and fixed without penetrating the screw 1.

(9) In the above embodiment, the screw 1 that is screwed from above to the bottom and screwed into the deck plate 10 to be fixed is illustrated, but the present invention is not limited to this. The screwing direction of the screw 1 with respect to the metal substrate may be any direction. For example, when the metal base is a side wall or the like, it may be a screw 1 that is screwed toward the side to fix it.

(10) In the above embodiment, a normal impact driver is exemplified as a tool, but the present invention is not limited to this. For example, when the environmental temperature is low, such as in winter, a heating portion may be provided at the tip of the bit of the impact driver to heat the screw 1. The heat of the heating portion is transferred to the resin layer 5 through the shaft portion 4, and the resin layer 5 is easily melted. Further, the engaging portion 2 of the square hole is illustrated, but the present invention is not limited to this. For example, it may be a hexagonal hole other than the square hole, a cross hole, a minus hole, or another engaging portion. In this case, the bit of the tool is used according to the shape of the engaging portion.

INDUSTRIAL APPLICABILITY The present invention can be used as a screw that can indirectly fix an object such as a waterproof sheet to a metal substrate by screwing it into the metal substrate and fixing it.

1: Screw 4: Shaft 5: Resin layer 7: Thread 9: Sharpened part 10: Deck plate (metal base)
θ: Lead angle

Claims (3)

It is a screw that can be screwed into a metal base and fixed.
A resin layer made of a thermoplastic material that wraps at least the tip of the shaft and is solid at room temperature and is melted by frictional heat when the shaft is screwed into the metal base is provided .
A screw in which the thickness of the resin layer is larger than that of other portions in the vicinity of the most advanced portion of the shaft portion . The screw according to claim 1, wherein the sharp end portion of the shaft portion is exposed without being covered with the resin layer. The screw according to claim 1 or 2 , wherein the lead angle of the screw portion in the shaft portion is smaller than the lead angle of the coarse screw.

Images