Screw for coupling wooden members together
There is provided a screw for fastening a wooden member which includes: a shank that extends along a datum line; a head that is disposed at an end of the shank and has a plate portion having a cross-section that narrows as it goes to the shank such that the boundary of the cross-section and the datum line make a plate angle; and a tapered blade that protrudes from the outer side of the plate portion, has a bottom perpendicular to the datum line and a side making an obtuse angle with the bottom, and has a taper angle that is made by the side and the datum line and is 2.50° to 12.5° smaller than the plate angle.
1. A screw for fastening a wooden member, comprising:
a shank extending along a datum line;
a head disposed at an end of the shank and having a plate portion having a cross-section that narrows as the plate portion extends to the shank such that a boundary of the cross-section and the datum line forms a plate angle; and
a tapered blade protruding from the boundary of the plate portion, the tapered blade having a bottom that is perpendicular to the datum line and a side that forms an obtuse angle with the bottom, and having a taper angle that is made by the side and the datum line and is 2.5° to 12.5° smaller than the plate angle.
2. The screw of claim 1 , wherein the plate angle is 27.5° to 30°.
3. The screw of claim 1 , wherein the shank has a threaded portion with a thread thereon, and the bottom of the tapered blade is positioned at a distance corresponding to one pitch to one and a half pitch of the thread further from the head than a bottom of the plate portion.
4. The screw of claim 3 , wherein the shank further has a neck connecting the threaded portion and the plate portion to each other, and
the neck has a reinforcing portion haying an outer diameter which is larger by 6.5% to 8% than a remaining portion of the neck.
5. The screw of claim 1 , wherein the head further has a disc portion connected to a free end of the plate portion and having a larger cross-sectional area than the plate portion.
6. The screw of claim 5 , further comprising a horizontal blade protruding from a bottom of the disc portion and connected to the tapered blade.
7. The screw of claim 6 , wherein the horizontal blade protrudes from the disc portion by 25% to 45% of a thickness of the disc portion.
8. The screw of claim 6 , further comprising a circular blade protruding from the bottom of the disc portion and forming a circle.
9. The screw of claim 8 , wherein the circular blade is formed such that an edge of the disc portion is bent to form an arc cross-section toward the shank.
10. The screw of claim 8 , wherein the tapered blade and the horizontal blade are disposed inside a range defined by the circular blade, in a range of the disc portion.
11. The screw of claim 8 , wherein the horizontal blade protrudes from the disc portion further than the circular blade.
12. The screw of claim 6 , wherein the bottom of the tapered blade is parallel with a bottom of the horizontal blade.
13. The screw of claim 5 , wherein a length of the bottom of the tapered blade is 7.5% to 12.5% of a radius of the disc portion.
14. The screw of claim 1 , wherein a thickness of the tapered blade is 0.25 to 0.35 mm.
15. The screw of claim 1 , wherein the shank further has an end blade that is formed at a free end of the shank and has an internal angle of 50° to 60°.
16. A screw for fastening a wooden member, comprising:
a shank extending along a datum line and having a threaded portion with a thread thereon and an end blade formed at one end;
a head disposed at the other end of the shank and having a plate portion, which has a cross-section that narrows as the plate portion extends to the shank such that a boundary of the cross-section and the datum line form a plate angle, and a disc portion at a free end of the plate portion;
a tapered blade protruding from the boundary of the plate portion, having a bottom that is perpendicular to the datum line and a side that forms an obtuse angle with the bottom, and having a tapered angle smaller than the plate angle;
a horizontal blade protruding from the bottom of the disc portion and having a bottom which is parallel with the bottom of the tapered blade; and
a circular blade protruding from the bottom of the disc portion and surrounding the tapered blade and the horizontal blade.
17. The screw of claim 16 , wherein the bottom of the tapered blade is positioned at a distance corresponding to one pitch to one and a half pitch of the thread further from the head than the bottom of the plate portion.
18. The screw of claim 17 , wherein the shank further has a neck connecting the threaded portion and the plate portion to each other, and the neck has a reinforcing portion having an outer diameter larger by 6.5% to 8% than a remaining portion of the neck.
19. The screw of claim 16 , wherein a length of the bottom of the tapered blade is 7.5% to 12.5% of a radius of the disc portion.
20. The screw of claim 16 , wherein the plate angle is 27.5° to 30° and the tapered angle is 17.5° to 25°.