screw

Abstract

To provide a screw suitable for a covering method for suppressing the occurrence of come-out that a bit comes off from the screw even if a rotational load is high.SOLUTION: A screw 1A comprises a head part 3 at which a recess 2A fit with a driver bit is formed, and a shaft part 4 at which a screw thread 40 is formed. The recess 2A has six pieces of apexes 20A in a peripheral direction of the head part, the apexes 20A are constituted of curve lines which become protrusive toward an external periphery of the head part 3, and a clearance between the apexes 20A is constituted of a curve line which becomes protrusive toward a center of the head part 3, and has an inside face 21A which is parallel to an axial direction of the shaft part 4. In the screw 1A, a thickness of the head part 3 is 1.2 mm or thicker and 2.4 mm or thinner, a depth of the recess 2A is 1.6 mm or deeper, and a wall thickness of a periphery of the recess 2A is 0.7 mm or thicker.SELECTED DRAWING: Figure 1B

Description

[Technical field]

[0001] The present invention relates to a screw used in roof construction and the like. [Background technology]

[0002] As a roof construction method, a method known as the covering method has been proposed for roofs in which slate material is attached to a wooden base, and then a metal sheet made of Galvalume Steel (registered trademark) is laid on top of the slate material.

[0003] Conventionally, impact drivers capable of applying impact in the rotational direction have been used in roof construction. When using an impact driver in the above-mentioned cover construction method, a strong pressing force is required from the worker using the impact driver to push the screw through the sheet metal or slate material. In addition, the high rotational load caused by applying impact in the rotational direction is likely to cause cam-out, in which the bit comes off the screw, and a stronger pressing force is required to prevent cam-out.

[0004] Therefore, in order to reduce the pressing force, it is conceivable to apply a screw driving machine equipped with an impact mechanism that drives the screw in the axial direction and then tightens it with a rotational motion, and a screw tightening mechanism, to the cover construction method, as described in Patent Document 1, etc. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-23169 A Summary of the Invention [Problem to be solved by the invention]

[0006] By using the above-mentioned screw driving machine in the cover construction method, the screws are driven into the sheet metal or slate material using air pressure, which reduces the pressing force required by the worker using the screw driving machine when driving the screws.

[0007] On the other hand, the characteristic of the cross bit commonly used for screws is that it is prone to cam-out, where the bit comes off the screw, when the rotation load is high. However, in the above-mentioned screw driving machine, the bit is pressed against the screw by air pressure when the screw is driven, and the screw is pressed against the object to be fastened via the bit, so even if the operator using the screw driving machine increases the pressing force, it is difficult to prevent cam-out caused by the characteristics of the cross recess.

[0008] The present invention has been made to solve such problems, and aims to provide a screw suitable for the cover construction method, which suppresses the occurrence of cam-out, in which the bit comes off the screw, even when the rotational load is high. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the present invention provides a screwdriver having a head portion having a recess into which a driver bit is fitted, and a shaft portion having a screw thread formed therein, The head portion has a protrusion protruding in a direction opposite to the shaft portion, Between the bearing surface formed on the shaft side of the head and the shaft, there is provided an expanded diameter portion having a diameter larger than that of the shaft, and the recess has at least three peaks along the circumferential direction of the head which rotates around the shaft, and the peaks are composed of straight lines or a combination of straight lines and curves that are concave toward the center of the head, or curves. The diameter of the outer circumferential circle passing through the top of the recess is equal to or greater than the diameter of the shank, the depth of the recess is equal to or greater than the thickness of the head, the enlarged diameter portion has a tapered surface whose diameter increases from the shank toward the head, and the length along the axial direction of the shank from the position where the diameter of the enlarged diameter portion is the same as the outer diameter of the thread to the seating surface of the head is 1.2 mm or more. It is a screw.

[0010] In the present invention, a bit having at least three peaks along the circumference of the head which rotates around the shaft, and between the peaks, a recess formed of a straight line or a combination of straight lines and curves concave toward the center of the head, or a curved line, is used to tighten the screw. Effect of the Invention

[0011] According to the present invention, it is possible to suppress the occurrence of cam-out, in which the bit comes off the screw, and it is possible to reliably transmit high torque between the bit and the screw. In addition, by providing an enlarged diameter portion between the shank and the seat formed on the head, the strength of the screw can be ensured. [Brief description of the drawings]

[0012] [Figure 1A] FIG. 2 is a cross-sectional view of a main portion showing an example of a screw according to the present embodiment. [Figure 1B] FIG. 2 is a cross-sectional view of a main portion showing an example of a screw according to the present embodiment. [Figure 1C] 11 is a cross-sectional view of a main portion showing another example of the screw according to the present embodiment. FIG. [Figure 1D] 11 is a cross-sectional view of a main portion showing another example of the screw according to the present embodiment. FIG. [Figure 1E] 11 is a cross-sectional view of a main portion showing a modified example of the screw of the present embodiment. FIG. [Figure 1F] 11 is a cross-sectional view of a main portion showing a modified example of the screw of the present embodiment. FIG. [Figure 1G] 13 is a cross-sectional view of a main portion showing another modified example of the screw of the present embodiment. FIG. [Figure 2A] FIG. 2 is a side view showing an example of a screw according to the present embodiment. [Figure 2B] FIG. 2 is a front view showing an example of a screw according to the present embodiment. [Figure 2C] FIG. 2 is a perspective view showing an example of a screw according to the present embodiment. [Figure 2D] 2C is a cross-sectional view taken along line AA in FIG. 2B, showing a screw according to an example of the present embodiment. [Figure 2E] 2C is a cross-sectional view taken along line BB in FIG. 2B, showing a screw according to an example of the present embodiment. [Figure 2F] FIG. 11 is a side view showing another example of the screw according to the present embodiment. [Figure 2G] 2C is a cross-sectional view taken along line AA in FIG. 2B, showing another example of a screw according to the present embodiment. [Figure 2H] 2B showing a cross-sectional view of a screw according to another embodiment of the present invention taken along line BB in FIG. 2B. [Figure 2I] FIG. 2 is a perspective view showing an example of a form in which the screw of the present embodiment is provided. [Figure 3A] FIG. 2 is a cross-sectional view showing a usage pattern of a screw according to an example of the present embodiment. [Figure 3B] FIG. 11 is a cross-sectional view showing a usage pattern of a screw according to another example of the present embodiment. [Figure 4A] FIG. 2 is a side view showing an example of a driver bit. [Figure 4B] FIG. 2 is a front view showing an example of a driver bit. [Figure 4C] FIG. 1 is a perspective view showing an example of a driver bit; [Figure 4D] 4B is an enlarged view of a portion C in FIG. 4A showing an example of a driver bit. FIG. [Figure 5A] 4 is a cross-sectional view showing a state in which a screw and a driver bit are fitted together. FIG. [Figure 5B] 4 is a cross-sectional view showing a state in which a screw and a driver bit are fitted together. FIG. [Figure 6A] 13 is a cross-sectional view of a main portion showing yet another modified example of the screw of the present embodiment. FIG. [Figure 6B] 13 is a cross-sectional view of a main portion showing yet another modified example of the screw of the present embodiment. FIG. [Figure 6C] 13 is a cross-sectional view of a main portion showing yet another modified example of the screw of the present embodiment. FIG. [Figure 6D] 13 is a cross-sectional view of a main portion showing yet another modified example of the screw of the present embodiment. FIG. [Figure 6E] 13 is a cross-sectional view of a main portion showing yet another modified example of the screw of the present embodiment. FIG. [Figure 6F] 13 is a cross-sectional view of a main portion showing yet another modified example of the screw of the present embodiment. FIG. [Figure 6G] 13 is a cross-sectional view of a main portion showing yet another modified example of the screw of the present embodiment. FIG. [Figure 6H] 13 is a cross-sectional view of a main portion showing yet another modified example of the screw of the present embodiment. FIG. [Figure 6I] 13 is a cross-sectional view of a main portion showing yet another modified example of the screw of the present embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the screw of the present invention will

[0014] <Example of the screw configuration according to this embodiment> 1A and 1B are cross-sectional views of the essential part showing an example of the screw of this embodiment, and FIG. 1B shows the dimensional relationship of the screw shown in FIG. 1A. Also, FIG. 1C and FIG. 1D are cross-sectional views of the essential part showing another example of the screw of this embodiment, and FIG. 1D shows the dimensional relationship of the screw shown in FIG. 1C. Furthermore, FIG. 1E and FIG. 1F are cross-sectional views of the essential part showing a modified example of the screw of this embodiment, and FIG. 1G is a cross-sectional view of the essential part showing another modified example of the screw of this embodiment. Also, FIG. 2A is a side view showing an example of the screw of this embodiment, FIG. 2B is a front view showing an example of the screw of this embodiment, and FIG. 2C is a perspective view showing an example of the screw of this embodiment. Furthermore, FIG. 2D is a cross-sectional view of the AA line of FIG. 2B showing the screw of the example of this embodiment shown in FIG. 2A, and FIG. 2E is a cross-sectional view of the BB line of FIG. 2B showing the screw of the example of this embodiment shown in FIG. 2A. Fig. 2F is a side view showing another example of the screw of this embodiment, Fig. 2G is a cross-sectional view taken along line AA in Fig. 2B showing the screw of the other example of this embodiment shown in Fig. 2F, Fig. 2H is a cross-sectional view taken along line BB in Fig. 2B showing the screw of the other example of this embodiment shown in Fig. 2F. Fig. 2I is a perspective view showing an example of a provision form of the screw of this embodiment. Fig. 3A is a cross-sectional view showing a usage form of the screw of the example of this embodiment shown in Fig. 1A, Fig. 3B is a cross-sectional view showing a usage form of the screw of the other example of this embodiment shown in Fig. 1C.

[0015] Fig. 4A is a side view showing an example of a driver bit used for the screw of the present embodiment shown in Fig. 1A, Fig. 1B, Fig. 1C, Fig. 1D, Fig. 1E, and Fig. 1F, Fig. 4B is a front view showing an example of the driver bit, Fig. 4C is a perspective view showing an example of the driver bit, and Fig. 4D is an enlarged view of part C in Fig. 4A showing an example of the driver bit. Figs. 5A and 5B are cross-sectional views showing the fitting state of the screw and the driver bit.

[0016] Screw 1A is used in a roof construction method known as a covering method, in which a first plate material, slate material 102 (or a roofing material called cement board) is attached to a wooden base 101 on a roof, in which a waterproof sheet 103 is sandwiched between the slate material 102 and a second plate material, metal sheet 104 made of galvalume steel (registered trademark), is then layered on top of the slate material 102, as shown in Figures 3A and 3B.

[0017] In the past, impact drivers capable of applying impact in the rotational direction have been used in roof construction. When using an impact driver in the above-mentioned covering method, a strong pressing force is required to fasten the screw 1A to the base 101 by penetrating the sheet metal 104 and the slate material 102.

[0018] Therefore, as described in JP 2010-23169 A, after the screw 1A is driven in the axial direction, the screw 1A is fastened using a screw driving machine equipped with a striking mechanism that fastens the screw by rotating, and a screw tightening mechanism. By using the screw driving machine, the load required to penetrate the screw 1A into the sheet metal 104 and the slate material 102 can be reduced.

[0019] On the other hand, the characteristic of the cross bit generally used for screws is that the bit is likely to come off the screw when the rotation load is high, which is a problem. As described above, in a screw driving machine, the bit is pressed against the screw by air pressure when the screw is driven, and the screw is pressed against the object to be fastened via the bit, so it is difficult to prevent the occurrence of cam-out due to the characteristics of the cross recess even if the pressing force by the operator using the screw driving machine is increased. Therefore, the screw 1A is configured to be fastened by a driver bit 201 equipped with a bit 200 of a shape called a hexalobular shape shown in Figures 4A to 4D, which is a recess shape that does not generate a force in the direction in which the screw and the bit separate, even when the rotation load is high.

[0020] The screw 1A will be described in detail below. The screw 1A has a head 3 in which a recess 2A into which a driver bit provided in a screw driving machine is fitted, and a shank 4 in which a screw thread 40 is formed on the outer circumferential surface.

[0021] Furthermore, in order to ensure sufficient wall thickness around the sides and bottom of the recess 2A, the screw 1A has an expanded diameter section 5 between the head 3 and the shank 4, the expanded diameter section 5 having a larger diameter than the shank 4. As shown in Fig. 2I, the screw 1A used in a screw driving machine is provided in a form in which multiple screws 1A are connected by connecting members 10A in a direction perpendicular to the axial direction of the shank 4 and wound spirally from the inner circumference to the outer circumference.

[0022] The recess 2A is configured as a concave portion with an opening on the top surface 30 of the head 3 to match the shape of the bit 200 of the driver bit 201. The recess 2A, which has a shape called a hexalobular shape, has six apexes 20A along the circumferential direction of the head 3 which rotates about the shaft 4, and the spaces between the apexes 20A are configured as curves that are concave toward the center of the head 3. Each apex 20A is configured as a curve that is convex toward the outer periphery of the head 3.

[0023] The recess 2A has an inner side surface 21A parallel to the axial direction in which the shaft portion 4 extends. The recess 2A shown in Figs. 1A, 1B, 1C, 1D, 1E, and 1F further includes a guide recess 22A for guiding the bit 200 of the driver bit 201 shown in Figs. 4A to 4D. In the example shown in Figs. 1A, 1B, 1C, and 1D, the guide recess 22A has a shape curved inwardly convex so that the diameter becomes smaller toward the bottom of the guide recess 22A in accordance with the shape of the conical protrusion 202 whose peripheral surface protrudes from the tip of the bit 200 of the driver bit 201 and is curved concavely. In the example shown in Fig. 1E, the guide recess 22A has a side surface formed of a linear inclined surface so that the diameter becomes smaller toward the bottom of the guide recess 22A. In the example shown in Fig. 1F, the guide recess 22A has a cylindrical shape into which the protrusion 202 of the driver bit 201 is inserted.

[0024] In the screw driving machine shown in JP 2010-23169 A and the like, the screw 1A is supplied in a connected form, and the bit 200 needs to be fitted into the recess 2A in the process of the driver bit 201 driving the screw 1A in the axial direction or in the process of the driver bit 201 rotating. Therefore, the guide recess 22A of the recess 2A guides the convex portion 202 protruding from the tip of the bit 200 of the driver bit 201, so that the bit of the driver bit 201 can be reliably fitted into the recess 2A of the screw 1A as shown in Figures 5A and 5B. That is, as shown in Figs. 1A, 1B, 1C, 1E, and 1F, the guide recess 22A has a shape in which the diameter becomes smaller toward the bottom of the guide recess 22A, for example, as shown in Figs. 1A, 1B, 1C, and 1D, the side surface of the guide recess 22A is curved to match the shape of the convex portion 202 of the driver bit 201 shown in Fig. 4D, or as shown in Fig. 1E, the side surface of the guide recess 22A is a linear inclined surface, so that the radial centers of the bit 200 and the recess 20A are guided in a direction to match each other by the operation of fitting the bit 200 of the driver bit 201 and the recess 2A of the screw 1A. This allows the bit of the driver bit 201 to be reliably fitted into the recess 2A of the screw 1A as shown in Fig. 5B. The recess 2A shown in Fig. 1G does not have a guide recess. In this case, a driver bit having no convex portion at the tip of the bit is used.

[0025] Now, the performance required for the screw used in the above-mentioned sheet metal cover construction method is to reliably fix the sheet metal 104, and when reliably fixing the sheet metal 104, it is important that the head of the screw does not float from the sheet metal 104 and does not sink into the sheet metal 104. In order to reliably fix the sheet metal 104, while suppressing an increase in the load during the operation of fastening the screw 1A, in order to ensure the strength that the shank 4 does not break, it is preferable that the diameter D1 of the shank 4 of the screw 1A is 2.7 mm or more and 3.3 mm or less. That is, in order to ensure the strength that the shank 4 does not break, it is preferable that the lower limit value of the diameter D1 of the shank 4 of the screw 1A is 2.7 mm or more. On the other hand, if the diameter of the shank 4 becomes thicker, the driving load and the rotation load during screwing increase, and the workability deteriorates, so that the upper limit value of the diameter D1 of the shank 4 is preferably 3.3 mm or less. In addition, in order to prevent the shank 4 of the fastened screw 1A from coming loose from the base 101, the outer diameter D2 of the thread 40 is preferably 4.0 mm or more, but taking into account the driving load and the rotational load during screwing, it is preferable that it be 4.5 mm or less.

[0026] Furthermore, in order to hold the metal plate 104 by the head 3 so that it does not come off, the diameter D3 of the head 3 is preferably 8.1 mm or more. On the other hand, the diameter of the head 3 of the screw 1A needs to be smaller than the inner diameter of the nose through which the screw passes in the screw driving machine. Furthermore, in order to suppress the angle at which the screw 1A tilts in the nose, it is better not to make the difference between the diameter D2 of the thread 40 of the shank 4 of the screw 1A and the diameter D3 of the head 3 too large. Therefore, in the case of the screw 1A having the outer diameter D2 of the thread 40 of about 4.0 mm, the upper limit of the diameter D3 of the head 3 is preferably 8.7 mm or less.

[0027] When the recess 2A has a shape called hexalobular, a driver bit with a size (nominal) of T20 or T25 is used for a screw 1A having an outer diameter D2 of the thread 40 of about 4.0 mm. In the recess 2A corresponding to a driver bit with a size T20, the spacing A1 between the apexes 20A located on the diagonal line passing through the center of the head 3 is 3.84 mm, and in the recess 2A corresponding to a driver bit with a size T25, the spacing A1 between the apexes 20A located on the diagonal line is 4.40 mm.

[0028] Furthermore, as shown in Figures 1A, 1B, 1C, 1D, 1E, and 1F, in a configuration in which the recess 2A has a guide recess 22A, in the recess 2A corresponding to a driver bit having a size of T20, the diameter A2 of the guide recess 22A is 2.85 mm or less, and in the recess 2A corresponding to a driver bit having a size of T25, the diameter A2 of the guide recess 22A is 3.3 mm or less.

[0029] In the above-mentioned covering method, the next metal plate 104 is placed on top of the metal plate 104 fixed by the screw 1A. Therefore, the top of the head 3 of the screw 1A exposed on the surface of the metal plate 104 fixed on the lower side is covered by the next metal plate 104.

[0030] The head 3 has a protrusion 33 that protrudes in the axial direction of the shaft 4 in the direction opposite to the side where the enlarged diameter portion 5 is provided. Therefore, the thickness T1 of the head 3 of the screw 1A is 1.2 mm or more to 2.4 mm or less. Under If the thickness T1 of the head 3 is 2.4 mm or less, even if a force is applied to the metal plate 104 placed on the head 3 of the screw 1A, the deformation of the metal plate 104 caused by being pressed against the head 3 of the screw 1A is suppressed.

[0031] The head 3 has a seat 31 on the outer periphery of the enlarged diameter portion 5, which contacts and holds the metal sheet 104 fixed to the base 101 via the slate material 102. When the screw 1A is fastened to fix the metal sheet 104, the seat 31, which is the surface of the head 3 facing the metal sheet 104, may be configured as a flat surface, or as a tapered surface consisting of a slope or curved surface whose diameter increases from the shaft 4 toward the outer periphery of the head 3, as in the form called a countersunk screw. When the seat 31 is configured as a flat surface, the screw 1A is screwed in until the entire surface of the seat 31, including the outer periphery of the head 3, is in contact with the surface of the metal sheet 104, so that the head 3 of the screw 1A does not float above the surface of the metal sheet 104. In contrast, when the seat 31 is configured as a tapered surface whose diameter increases from the shank 4 toward the outer periphery of the head 3, it will have a form that protrudes from the outer periphery of the head 3 toward the shank 4 along the axial direction of the shank 4, so that the screw 1A is screwed in until the outer periphery of the head 3 comes into contact with the surface of the sheet metal 104 while a part of the seat 31 crushes the sheet metal 104, so that the head 3 of the screw 1A does not float above the surface of the sheet metal 104. Therefore, the state in which the head 3 of the screw 1A does not float above the surface of the sheet metal 104 means that the outer periphery of the seat 31, which is the outer periphery of the head 3, comes into contact with the surface of the sheet metal 104.

[0032] Therefore, the outer periphery of the seat 31 is referred to as the seat reference surface 32. In a configuration in which the head 3 has a convex portion 33, the thickness T1 of the head 3 is the length along the axial direction of the shaft portion 4 from the top surface 30 of the head 3 to the seat reference surface 32. In addition, in a case in which the seat 31 is a flat surface, the thickness T1 of the head 3 is the length along the axial direction of the shaft portion 4 from the top surface 30 of the head 3 to the seat 31.

[0033] In the case of the screw 1A whose recess 2A size corresponds to a driver bit having a size of T20, the thickness T1 of the head 3 is preferably 1.2 mm or more and 2.3 mm or less, and the upper limit of the thickness T1 of the head 3 is more preferably 2.0 mm or less. In the case of the screw 1A whose recess 2A size corresponds to a driver bit having a size of T25, the thickness T1 of the head 3 is preferably 1.6 mm or more and 2.3 mm or less, and the upper limit of the thickness T1 of the head 3 is more preferably 2.0 mm or less.

[0034] In order to ensure a contact area between the driver bit and the inner surface 21A of the recess 2A, the depth Dep1 of the recess 2A is preferably 1.6 mm or more. If the depth Dep1 of the recess 2A is 1.6 mm or more, the occurrence of cam-out, in which the driver bit comes off the recess 2A when fastening the screw 1A with the driver bit, is suppressed, and the driver bit can apply a force to the screw 1A necessary and sufficient for fastening.

[0035] In addition, as shown in Figures 1A, 1B, 1C, 1D, 1E, and 1F, in a configuration in which the recess 2A includes the guide recess 22A, the depth Dep2 of the guide recess 22A is preferably 1.2 mm or more and 2.1 mm or less. In the case of a screw 1A in which the recess 2A size corresponds to a driver bit of T20, the depth Dep2 of the guide recess 22A is preferably 1.2 mm or more and 2.1 mm or less. In the case of a screw 1A in which the recess 2A size corresponds to a driver bit of T25, the depth Dep2 of the guide recess 22A is preferably 1.5 mm or more and 2.1 mm or less.

[0036] As described above, the recess 2A corresponding to the driver bit of size T25 has a diameter of an outer circumference passing through each apex 20A, in this example, a distance A between the diagonally positioned apexes 20A is 4.4 mm, and the radial size of the recess 2A is larger than the diameter D1 of the shank 4. On the other hand, the thickness T1 of the head 3 of the screw 1A is preferably 2.0 mm or less, while the depth Dep1 of the recess 2A is preferably 1.6 mm or more.

[0037] The thickness of the sides and the periphery of the bottom of the recess 2A is preferably 0.7 mm or more. In contrast, in the above dimensional relationship, if the screw has a flat seat 31 and the shank 4 is not provided with the enlarged diameter portion 5 and is shaped to connect to the seat 31 with approximately the same diameter, the thickness between the bottom of the recess 2A and the seat 31 of the head 3 can be secured at most 0.4 mm, which does not satisfy the value stipulated in the present invention. Therefore, in a screw having a shape in which the shank 4 is not provided with the enlarged diameter portion 5 and is shaped to connect to the seat 31 with approximately the same diameter, the required thickness cannot be secured around the sides and the bottom of the recess 2A.

[0038] Therefore, in order to ensure the thickness around the sides and bottom of the recess 2A, the screw 1A is provided with an enlarged diameter portion 5 between the head 3 and the shank 4, the enlarged diameter portion 5 having a larger diameter than the shank 4. By providing the enlarged diameter portion 5 between the head 3 and the shank 4, the depth Dep1 of the recess 2A can be made equal to or greater than the thickness T1 of the head 3 of the screw 1A.

[0039] In this case, when the recess 2A has a shape called hexalobular and includes a guide recess 22A as shown in Fig. 1A, Fig. 1B, and Fig. 1C, the thickness T2 between the recess 2A and the enlarged diameter portion 5 around the sides and bottom of the recess 2A is the thinnest between the top 20A of the recess 2A and the enlarged diameter portion 5, or between the guide recess 22A of the recess 2A and the enlarged diameter portion 5. When the recess 2A does not include a guide recess as shown in Fig. 1D, the thickness T2 between the recess 2A and the enlarged diameter portion 5 is the thinnest between the top 20A of the recess 2A and the enlarged diameter portion 5. The thinnest part of the thickness T2 between the recess 2A and the enlarged diameter portion 5 is preferably 0.7 mm or more.

[0040] Now, in the screw 1A having an enlarged diameter portion 5 between the head 3 and the shank 4, if the length along the axial direction of the shank 4 from the starting point 51 of the enlarged diameter portion 5, where the diameter (diameter) is larger than that of the shank 4, to the seat reference surface 32 (seat 31) of the head 3 is less than the sum of the thicknesses of the metal sheet 104 and the waterproof sheet 103, which in this example is 1.35 mm, then even if the screw 1A is screwed in until the seat reference surface 32 (seat 31) of the head 3 is in close contact with the metal sheet 104, the enlarged diameter portion 5 will not reach the slate material 102.

[0041] However, in this case, if the expanded diameter portion 5 is configured as a tapered surface whose diameter increases from the starting point 51 of the expanded diameter portion 5 toward the seating surface reference surface 32, the thickness T2 between the recess 2A and the expanded diameter portion 5 will be less than 0.7 mm at its thinnest part.

[0042] In contrast, consider a configuration in which the length along the axial direction of the shaft portion 4 from the starting point 51 of the enlarged diameter portion 5 to the seat reference surface 32 (seat 31) of the head 3 exceeds the combined thickness of the metal plate 104 and the waterproof sheet 103.

[0043] In this case, the expanded diameter portion 5 reaches the slate material 102. However, in the hole in the slate material 102 where the thread 40 passed during the fastening operation of the screw 1A, the slate material 102 is destroyed at the portion inside the outer diameter D2 of the thread 40 on the opening side facing the waterproof sheet 103 when the thread 40 penetrates. Therefore, in the vicinity of the side of the slate material 102 facing the waterproof sheet 103, even a portion of the expanded diameter portion 5 that is thicker than the diameter D1 of the shaft portion 4 can penetrate into the slate material 102.

[0044] Therefore, in the expanded diameter portion 5, the length L1 along the axial direction of the shaft portion 4 from position P1, which is a portion having the same diameter as the outer diameter D2 of the thread 40, to the bearing surface reference surface 32 (bearing surface 31) of the head 3, is preferably approximately equal to the combined value of the thickness of the metal plate 104 and the waterproof sheet 103, and is preferably 1.2 mm or more, and in this example, is approximately 1.35 mm to 1.65 mm. In this example, since the outer diameter D2 of the thread 40 is 4.2 mm, it is preferable that the diameter of the expanded diameter portion 5 at position P1, which is 1.2 mm or more away from the bearing surface reference surface 32 (bearing surface 31) of the head 3 along the axial direction of the shaft portion 4, is 4.2 mm or less.

[0045] In addition, in order to ensure that the thickness T2 between the recess 2A and the expanded diameter portion 5 is 0.7 mm or more at its thinnest point, it is preferable that the length L2 from the starting point 51 of the expanded diameter portion 5 to the seat reference surface 32 (seat 31) of the head 3 is 1.5 mm or more and 3.5 mm or less.

[0046] When the recess 2A is configured to include the guide recess 22A, the length L2 from the starting point 51 of the enlarged diameter portion 5 to the bearing surface reference surface 32 (bearing surface 31) of the head 3 is preferably 1.7 mm or more and 2.6 mm or less. When the recess 2A is a screw 1A that corresponds to a driver bit with a size of T20, the length L2 from the starting point 51 of the enlarged diameter portion 5 to the bearing surface reference surface 32 (bearing surface 31) of the head 3 is preferably 1.7 mm or more and 2.6 mm or less. When the recess 2A is a screw 1A that corresponds to a driver bit with a size of T20, the length L2 from the starting point 51 of the enlarged diameter portion 5 to the bearing surface reference surface 32 (bearing surface 31) of the head 3 is preferably 1.7 mm or more and 2.6 mm or less.

[0047] When the recess 2A is configured not to have the guiding recess 22A, the length L2 from the starting point 51 of the enlarged diameter portion 5 to the bearing surface reference surface 32 (bearing surface 31) of the head 3 is preferably 1.5 mm or more and 3.5 mm or less. When the screw 1A has a recess 2A size corresponding to a driver bit of T20, the length L2 from the starting point 51 of the enlarged diameter portion 5 to the bearing surface reference surface 32 (bearing surface 31) of the head 3 is preferably 1.7 mm or more and 3.5 mm or less. When the screw 1A has a recess 2A size corresponding to a driver bit of T20, the length L2 from the starting point 51 of the enlarged diameter portion 5 to the bearing surface reference surface 32 (bearing surface 31) of the head 3 is preferably 1.7 mm or more and 2.9 mm or less.

[0048] Further, the expanded diameter portion 5 contacts the metal plate 104 between position P1, where the diameter is the same as the outer diameter D2 of the thread 40, and the bearing surface reference surface 32 (bearing surface 31) of the head 3. In order to prevent the head 3 of the screw 1A from floating above the surface of the metal plate 104, the bearing surface reference surface 32, which is the outer periphery of the head 3, needs to be in contact with the surface of the metal plate 104. For this reason, in order to deform the metal plate 104 and the waterproof sheet 103, the expanded diameter portion 5 is provided with a tapered surface 50 whose diameter increases from the shaft portion 4 toward the head 3, between position P1, where the diameter is the same as the outer diameter D2 of the thread 40, and the bearing surface reference surface 32 (bearing surface 31) of the head 3.

[0049] When the recess 2A is configured to include the guide recess 22A and the diameter D3 of the head 3 is 8.4 mm, the angle α of the tapered surface 50 is preferably 70° or more and 115° or less. When the screw 1A has a recess 2A size corresponding to a T20 driver bit, the angle α of the tapered surface 50 is preferably 76° or more and 115° or less. When the screw 1A has a recess 2A size corresponding to a T25 driver bit, the angle α of the tapered surface 50 is preferably 70° or more and 115° or less.

[0050] When the recess 2A is configured without the guiding recess 22A and the diameter D3 of the head 3 is 8.4 mm, the angle α of the tapered surface 50 is preferably 38° or more and 115° or less. When the screw 1A has a recess 2A size corresponding to a T20 driver bit, the angle α of the tapered surface 50 is preferably 38° or more and 115° or less. When the screw 1A has a recess 2A size corresponding to a T25 driver bit, the angle α of the tapered surface 50 is preferably 57° or more and 115° or less.

[0051] When the angle α of the tapered surface 50 is the above value, the thickness T2 between the recess 2A and the expanded diameter portion 5 can be made 0.7 mm or more at the thinnest portion, and the depth Dep1 of the recess 2A can be made 1.6 mm or more. Furthermore, by providing the expanded diameter portion 5, the depth Dep1 of the recess 2A can be made equal to or greater than the thickness T1 of the head 3 of the screw 1A in a configuration in which the thickness T1 is 1.2 mm or more and 2.4 mm or less.

[0052] For this reason, the depth Dep1 of the recess 2A is preferably 1.6 mm or more and 2.5 mm or less. In the case of the screw 1A in which the size of the recess 2A corresponds to a driver bit of T20, the depth Dep1 of the recess 2A is preferably 1.6 mm or more and 2.5 mm or less. In the case of the screw 1A in which the size of the recess 2A corresponds to a driver bit of T25, the depth Dep1 of the recess 2A is preferably 1.6 mm or more and 2.0 mm or less.

[0053] On the other hand, if the angle α of the tapered surface 50 exceeds the above value, the area of ​​the seat 31 may become small, or a flat surface that becomes the seat 31 may not be formed. In order to ensure the area of ​​the seat 31 without making the outer diameter of the head 3 larger than the above value, a seat-under connecting surface 50a may be provided between the tapered surface 50 and the seat 31, and the tapered surface 50 and the seat 31 may not be directly connected to each other, so as to have a so-called stepped shape. The angle β (half angle) of the seat-under connecting surface 50a is preferably 0° or more and 35° or less, and may be constituted by a tapered surface with an angle different from that of the tapered surface 50 as shown in Figures 1A and 1B, or may be constituted by a straight surface along the axial direction of the shaft portion 4 as shown in Figures 1C and 1D. Furthermore, it is preferable that the length L3 of the seat-under connecting surface 50a along the axial direction of the shaft portion 4, i.e., the length from the seat-under reference surface 32 (seat 31) of the head 3 to the connecting point P2 between the seat-under connecting surface 50a and the tapered surface 50, is 0.3 mm or more and 1.3 mm or less. Furthermore, as shown in Figures 1A and 1B, between the tapered surface 50 composed of a linear inclined surface and the starting point 51 of the enlarged diameter portion 5, in this example, between the position P1 and the starting point 51 of the enlarged diameter portion 5, a curved surface 50b that is concave toward the center of the shaft portion 4 may be formed. By constructing the area from position P1 to the starting point 51 of the enlarged portion 5 with a curved surface 50b that is concave toward the center of the shaft 4, the length L2 from the starting point 51 of the enlarged portion 5 to the seat reference surface 32 (seat 31) of the head 3 can be extended within a specified range while suppressing the increase in load when fastening the screw 1A, thereby ensuring the thickness T2 between the recess 2A and the enlarged portion 5 and deepening the depth Dep1 of the recess 2A.

[0054] 6A to 6I are cross-sectional views of the main part showing still another modified example of the screw of this embodiment. In the enlarged diameter portion 5, if the diameter is smaller than the outer diameter D2 of the thread 40 between the position P1 where the diameter is the same as the outer diameter D2 of the thread 40 and the starting point 51 of the enlarged diameter portion 5, it can penetrate into the slate material 102. Therefore, the enlarged diameter portion 5 may be provided with a tapered surface where the diameter increases from the starting point 51 to the position P1 where the diameter is the same as the outer diameter D2 of the thread 40, between the position P1 where the diameter is the same as the outer diameter D2 of the thread 40 and the starting point 51 of the enlarged diameter portion 5. In the enlarged diameter portion 5, the tapered surface 52a provided between the position P1 where the diameter is the same as the outer diameter D2 of the thread 40 and the starting point 51 of the enlarged diameter portion 5 may have the same angle as the tapered surface 50, or as shown in FIG. 6A, the angle α1 (half angle) of the tapered surface 50 and the angle α2 (half angle) of the tapered surface 52a provided between the position P1 and the starting point 51 of the enlarged diameter portion 5 may be different angles. In this case, the position where the tapered surface 50 and the tapered surface 52 are connected may not coincide with the position P1 where the diameter is the same as the outer diameter D2 of the thread 40. A virtual circle C1 is shown by a two-dot chain line, with the recess 2A side as the center and the minimum value (0.7 mm in this example) obtained as the wall thickness T2 between the recess 2A and the enlarged diameter portion 5 as the radius. The angle between each tapered surface is set to a value such that each tapered surface does not fall inside an imaginary circle C1 centered on an arbitrary point O on the recess 2A side, and the thickness T2 between the recess 2A and each tapered surface will be equal to or greater than the desired value.

[0055] 6B, the area between position P1 and starting point 51 of enlarged diameter portion 5 may be formed with curved surface 52b that is convex toward the center of shaft portion 4 so as not to be inside imaginary circle C1 centered on any point O on the recess 2A side. Furthermore, as shown in FIG. 6C, enlarged diameter portion 5 may be formed with tapered surface 50 that increases in diameter from shaft portion 4 toward head 3 on the side closer to shaft portion 4 and does not enter inside imaginary circle C1 centered on any point O on the recess 2A side, between position P1 where the diameter is the same as the outer diameter D2 of thread 40 and bearing reference surface 32 (bearing surface 31) of head 3, so as not to be inside imaginary circle C1, and with straight surface 53a that is aligned along the axial direction of shaft portion 4 on the side closer to bearing surface 31 so as not to be inside imaginary circle C1 centered on any point O on the recess 2A side. Further, the enlarged diameter portion 5 may be provided with a step portion between a position P1 where the diameter is the same as the outer diameter D2 of the thread 40 and a starting point 51 of the enlarged diameter portion 5, the step portion having a diameter increasing from the starting point 51 to the position P1 where the diameter is the same as the outer diameter D2 of the thread 40. Furthermore, as shown in Fig. 6D, the enlarged diameter portion 5 may be configured to have a step portion 53b that follows the shape of the recess 2A between the position P1 where the diameter is the same as the outer diameter D2 of the thread 40 and the bearing reference surface 32 (bearing surface 31) of the head 3, so that the wall thickness T2 between the recess 2A and the enlarged diameter portion 5 is approximately uniform.

[0056] 6E, the enlarged diameter portion 5 may be configured such that the section between the bearing surface 31 of the head 3 and the position P1 where the diameter is the same as the outer diameter D2 of the thread 40, and the section between the position P1 and the starting point 51 of the enlarged diameter portion 5, is made up of an arc C2 of a single diameter or a combination of arcs of multiple different diameters, and the curved surface 54a does not fall inside the imaginary circle C1 centered on an arbitrary point O on the recess 2A side. Furthermore, as shown in FIG. 6F, the enlarged diameter portion 5 may be configured such that the bearing surface 31 is made up of a tapered surface made up of an inclined surface or a curved surface whose diameter increases from the shaft portion 4 toward the outer periphery of the head 3, and the section between the bearing surface reference surface 32 of the head 3 and the position P1 where the diameter is the same as the outer diameter D2 of the thread 40, and the section between the position P1 and the starting point 51 of the enlarged diameter portion 5, is made up of an arc C2 of a single diameter or a combination of arcs of multiple different diameters, and the curved surface 54b does not fall inside the imaginary circle C1 centered on an arbitrary point O on the recess 2A side.

[0057] 6G, the screw 1A may have a head 3 in a form called a button head, so long as the tapered surface 50, which faces the guiding recess 22A of the recess 2A, in the enlarged diameter portion 5 does not fall inside an imaginary circle C1 centered on an arbitrary point O on the recess 2A side. Furthermore, as shown in FIG. 6H, even if the tapered surface 50 in the enlarged diameter portion 5 extends to the outer periphery of the head 3 and the seating surface 31 is configured as a tapered surface whose diameter increases from the shank 4 toward the outer periphery of the head 3, the screw 1A may have a head 3 in a form called a button head.

[0058] Furthermore, as shown in FIG. 6I, when the head 3 does not have a convex portion 33 and the screw 1A is in the form of a flat head screw, a portion of the tapered surface 50 forms the seating surface 31, but as long as the depth Dep1 of the recess 2A is 1.6 mm or more, and the tapered surface 50 facing the recess 2A and the guiding recess 22A is not inside the imaginary circle C1 centered on an arbitrary point O on the recess 2A side, and further, a portion of the tapered surface 50 presses against the sheet metal 104, and the screw 1A can be screwed in until the outer periphery of the head 3 (seat reference surface 32) comes into contact with the surface of the sheet metal 104, the screw 1A may be in the form of a flat head screw.

[0059] As described above, the screw 1A has a recess 2A into which a driver bit fits, which has at least three apexes 20A along the circumferential direction of the head 3 which rotates around the shank 4, and the spaces between the apexes 20A are composed of straight lines or a combination of straight lines and curves that are concave toward the center of the head 3, or curves, and an enlarged diameter section 5 having a larger diameter than the shank 4 is provided between the seat 31 of the head 3 and the shank 4, thereby achieving the effect of suppressing the occurrence of cam-out while ensuring the strength of the screw 1A.

[0060] The screw 1A preferably has dimensions of each part that satisfy the values ​​stipulated in the present invention as described above. That is, the diameter D3 of the head 3 is 8.1 mm or more and 8.7 mm or less, the thickness T1 of the head 4 is 1.2 mm or more and 2.4 mm or less, the depth Dep1 of the recess 20A is 1.6 mm or more and 2.5 mm or less, the diameter D1 of the shank 4 is 2.7 mm or more and 3.3 mm or less, the diameter D2 of the thread 40 of the shank 4 is 4.1 mm or more and 4.35 mm or less, the thickness T2 between the recess 2A and the enlarged diameter portion 5 is 0.7 mm or more, and the length L2 along the axial direction of the shank 4 from the starting point 51 of the enlarged diameter portion 5 where the shank 4 and the enlarged diameter portion 5 intersect to the bearing surface 31 (bearing surface reference surface 32) of the head 3 is 1.5 mm or more and 3.1 mm or less.

[0061] Moreover, the angle α of the tapered surface 50 is not less than 38° and not more than 115°, and when the guide recess 22A is provided, the angle α of the tapered surface 50 is not less than 70° and not more than 115°.

[0062] Furthermore, the diameter of the expanded diameter portion 5 at a position P1 that is 1.2 mm or more away from the seating surface 31 (seating surface reference surface 32) of the head 3 along the axial direction of the shaft portion 4 is 4.2 mm or less.

[0063] By having the dimensions of each part of screw 1A satisfy the values ​​specified in the present invention, it is possible to achieve, in the above-mentioned cover construction method, that when fixing sheet metal 104, head 3 of screw 1A does not float above sheet metal 104, and head 3 of screw 1A does not sink into sheet metal 104.

[0064] As a result, in the cover construction method, by using a screw driving machine equipped with a striking mechanism that fastens the screw by rotating after driving the screw 1A in the axial direction and a screw tightening mechanism, it is possible to reduce the load required to penetrate the screw 1A into the sheet metal 104 and the slate material 102. In addition, even if the rotation load is high, it is possible to suppress the occurrence of cam-out, in which the bit 200 comes off the screw 1A.

[0065] In addition, in the screw 1A, the recess 2A is not limited to the shape called hexalobular, and may be a rectangle having four apexes 20A along the circumferential direction of the head 3, with straight lines between the apexes 20A, and with inner surface 21A parallel to the axial direction of the shank 4 from each side of the rectangle; a hexagon having six apexes 20A along the circumferential direction of the head 3, with straight lines between the apexes 20A, and with inner surface 21A parallel to the axial direction of the shank 4 from each side of the hexagon;

[0066] Now, in order to make connections that require a high torque when turning the screw to fasten components that have a high tightening load, such as fastening hard wood pieces together, it is essential that the torque generated by the tool be transmitted reliably to the screw without camming out, and that the screw be strong enough so that it will not break even when tightened with high torque.

[0067] To prevent cam-out, it is effective to form a deep recess in the screw. If the thickness of the screw head is increased in order to form a deep recess, the amount of protrusion of the screw head from the surface of the object to be fastened increases. On the other hand, if the recess is formed deep without increasing the thickness of the screw head, it becomes necessary to provide an enlarged diameter portion with a larger diameter than the shank on the underside of the head due to the relationship between the size of the recess and the diameter of the shank where the threads are provided.

[0068] However, since the enlarged diameter portion provides resistance when the screw sinks into the object to be fastened during the fastening operation, the larger the diameter of the enlarged diameter portion is made to ensure the strength of the screw, the higher the torque required to fasten the screw, making it difficult to achieve the effect of ensuring the strength of the screw.

[0069] In contrast, in the screw 1A of this embodiment, the shape of the recess 2A, the diameter of the enlarged diameter portion 5, and the length along the axial direction of the shaft portion 4 are specified, so that the increase in load when the enlarged diameter portion 5 sinks into the object to be fastened during the fastening operation of the screw 1A is minimized, and the torque can be reliably transmitted from the driver bit 201 to the screw 1A. This makes it possible to achieve the goals of reliably transmitting high torque, ensuring the strength of the screw 1A, and suppressing the increase in torque required for fastening the screw 1A, without increasing the thickness of the head 3. Therefore, the screw 1A can be used not only in the above-mentioned cover construction method, but also effectively in fastening members that have a high tightening load, such as fastening hard wood pieces together. [Explanation of symbols]

[0070] 1A...screw, 2A...recess, 20A...top, 21A...inner surface, 22A...guiding recess, 3...head, 30...top surface, 31...seat, 32...seat reference surface, 33...convex portion, 4...shaft, 40...thread, 5...expanded portion, 50...tapered surface, 50a, seat lower connecting surface, 50b...curved surface, 51...starting point, 101...base, 102...slate material, 104...sheet metal, 200...bit, 201...driver bit

Claims

1. a head portion having a recess into which a driver bit is fitted; a shaft portion on which a screw thread is formed, The head portion includes a protrusion protruding in a direction opposite to the shaft portion, a bearing surface formed on the head portion on the shaft portion side and between the shaft portion and the bearing surface, The recess has at least three apexes along a circumferential direction of the head which rotates about the shaft portion, The recess is formed between the apexes by a straight line or a combination of straight lines and curves that are concave toward the center of the head, or by a curve, and the diameter of an outer circumferential circle passing through the apex of the recess is equal to or greater than the diameter of the shaft portion; The depth of the recess is equal to or greater than the thickness of the head, The enlarged diameter portion has a tapered surface whose diameter increases from the shaft portion toward the head portion, and the length along the axial direction of the shaft portion from a position where the diameter of the enlarged diameter portion is the same as the outer diameter of the thread to the seat surface of the head portion is 1.2 mm or more. screw.

2. The recess has an inner surface parallel to the axial direction of the shaft portion. The screw according to claim 1.

3. The depth of the recess is 1.6 mm or more and 2.5 mm or less. The screw according to claim 1 or 2.

4. The recess is provided with a guide recess for guiding a bit of a driver bit into the recess. The screw according to any one of claims 1 to 3.

5. The angle of the tapered surface is greater than or equal to 70° and less than or equal to 115°. The screw according to any one of claims 1 to 3.

6. The enlarged diameter portion has a tapered surface whose diameter increases from the shaft portion toward the head portion, The angle of the tapered surface is equal to or greater than 38° and equal to or less than 115°. The screw according to claim 4.

7. The length along the axial direction of the shaft portion from the starting point of the enlarged diameter portion where the shaft portion and the enlarged diameter portion intersect to the seat surface of the head is 1.5 mm or more and 3.5 mm or less. The screw according to any one of claims 1 to 6.

8. The recess has six apexes along the circumferential direction of the head, each apex being configured with a curve that is convex toward the outer periphery of the head, and the spaces between the apexes being configured with a curve that is concave toward the center of the head. The screw according to any one of claims 1 to 6.

9. The thickness of the head is 1.2 mm or more and 2.4 mm or less. The screw according to any one of claims 1 to 8.

10. The head has a seat provided on the outer periphery of the enlarged portion, and the seat is configured as a flat surface. The screw according to any one of claims 1 to 9.

11. A plurality of the screws are connected by a connecting member in a direction perpendicular to the axial direction of the shaft portion, and are wound in a spiral shape from the inner circumference side to the outer circumference side. The screw according to any one of claims 1 to 10.

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