DRIVABLE SCREW NAIL

Abstract

In an impact-driven threaded nail, a thread has a steep lead angle of about 45 in order to attach a material with the nail by hitting a nail head and causing the threaded nail to rotate. When external force is applied in a direction to pull back the attached material from an underlying material, the threaded nail is often slightly rotated in a loosening direction, thereby generating a gap between the underlying material and the attached material, particularly in the case of the attached material being a thin sheet such as plywood. The present invention addresses the problem of providing an impact-driven threaded nail equipped with a means for preventing the above-mentioned loosening. The solution means resides in that a tapered portion of the head of the impact-driven threaded nail on a back-surface side thereof is formed in a pyramidal shape having a regular polygonal cross-section with a diameter decreasing gradually toward the nail shank. By driving the impact-driven threaded nail until an upper surface of the threaded nail head becomes flush with a surface of the attached material, an effect of preventing the threaded nail from rotating is obtained with the aid of both restoration force due to elastic deformation of the attached material and pressing force acting on the regular polygonal surface of the threaded nail head when the attached material is going to be pulled back.

Claims

1-5. (canceled)

6. An impact-driven threaded nail including a threaded portion with a lead angle of about 45, the threaded portion being formed along an outer circumference of a nail shank that has one end in the form of a pointed tip, and a head having a larger diameter than the nail shank, the head being integrally provided at the other end of the nail shank, wherein a portion of the head on a back-surface side in continuation with the nail shank is formed in a pyramidal shape having one of regular pentagonal to octagonal cross-sections with a diameter decreasing gradually toward the nail shank.

7. The impact-driven threaded nail according to claim 6, wherein the tapered portion of the head on the back-surface side has a regular hexagonal sectional shape.

8. An impact-driven threaded nail, analogous to a so-called screw nail, including a threaded portion provided with ridges and grooves in multiple threads, the threaded portion being formed along an outer circumference of a nail shank that has one end in the form of a pointed tip, and a head having a larger diameter than the nail shank, the head being integrally provided at the other end of the nail shank, wherein a portion of the head on a back-surface side in continuation with the nail shank is formed in a pyramidal shape having one of regular tetragonal to octagonal cross-sections with a diameter decreasing gradually toward the nail shank.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0023] FIGS. 1(a) and 1(b) are respectively a plan view and a front view, each representing an impact-driven threaded nail according to a first embodiment of the present invention.

[0024] FIG. 2 is an enlarged view representing a thread shape.

[0025] FIGS. 3(a), 3(b), 3(c) and 3(d) are respectively a plan view, a front view, a side view, and a sectional view of a head of the impact-driven threaded nail.

[0026] FIGS. 4(a) and 4(b) are respectively a plan view and a front view, each representing an embodiment different from the first embodiment.

[0027] FIG. 5 is a sectional view representing a state where the impact-driven threaded nail is driven into wood materials for fixing them.

[0028] FIGS. 6(a) and 6(b) are respectively a plan view and a front view, each representing a screwing threaded nail (so-called coarse thread).

[0029] FIGS. 7(a) and 7(b) are respectively a plan view and a front view of a screw nail.

[0030] FIGS. 8(a) and 8(b) are respectively a plan view and a front view, each representing a screw nail in which a back-side surface of a head is formed into a regular hexagonal shape to prevent loosening of the nail.

[0031] FIGS. 9(a) and 9(b) are respectively a plan view and a front view of a nail, which is dedicated for an underlying steel material, according to still another embodiment of the present invention.

[0032] FIGS. 10(a), 10(b) and 10(d) are respectively a plan view, a front view, and a sectional view of a screwing threaded nail having a flexible head with ribs.

DESCRIPTION OF EMBODIMENTS

[0033] An embodiment of the present invention will be described in detail below. In an impact-driven threaded nail 1 illustrated in FIG. 1, a head 3 is integrally formed at one end of a shank 2, and the other end of the shank 2 is formed into a pointed tip 4. Details of Embodiment and EXAMPLE 1

[0034] A threaded portion 5 is formed along an outer circumference of the shank 2. In this embodiment, the threaded portion 5 is divided into upper and lower parts such that an unthreaded shank portion 6 having a circular columnar shape and being not threaded remains between both the parts. An upper threaded portion (on the head side) A has a lead angle of 42, and a lower threaded portion (on the tip side) B has a larger lead angle, i.e., 45.

[0035] Although the threaded portion is divided into the portions A and B, the upper threaded portion and the lower threaded portion are formed in the discrete form allowing the lead angles in those portions and a length of the unthreaded shank portion 6 to be adjusted such that, when the driving of the nail is progressed, the upper threaded portion is driven in a good matched relation to screwing tracks of the lower threaded portion. The reason why the lead angle of the tip-side threaded portion B is relatively large and the lead angle of the head-side threaded portion A is relatively small resides in causing the upper threaded portion to be closely engaged in the screwing tracks formed by the lower threaded portion, and in ensuring reliable fixing.

[0036] The threaded portions A and B are each in the form of a quadruple-thread screw, and thread ridges have a shape as per illustrated in FIG. 2. In the upper threaded portion A, a lower-height thread ridge is formed at alternate thread of the quadruple-thread screw for volume adjustment. In the lower threaded portion B, however, all thread ridges have the same height. While tips of various types of ordinary nails (see paragraph [0002]) have rectangular pyramidal shapes with apex angles of about 30, the pointed tip of the impact-driven threaded nail has a conical shape with a fairly larger apex angle of 60, for example, in order to not only promote rotation of the threaded nail, but also to prevent cracking of wood when the nail is driven.

[0037] The thread ridge is shaped, as illustrated in FIG. 2, such that an angle of a sloping flank on the head side is 45 and an angle of a sloping flank on the tip side is 15. The reason why the angle of the sloping flank of the thread ridge is set to be relatively small on the tip side and relatively large on the head side resides in ensuring that the impact-driven threaded nail more efficiently receives force in the rotating direction when the nail is driven, and that it can be more easily pulled out by receiving rotating force when the nail is pulled out.

[0038] The head has a shape as per illustrated in FIG. 3. As seen from FIG. 3, a portion of the head on the back-surface side (i.e., the side nearer to the shank) is formed in a pyramidal shape having a regular hexagonal cross-section. An internal angle defining the pyramidal portion, denoted by a Greek letter in FIG. 3, is 70. When the number of angles of the pyramidal portion is increased as represented by an octagon, for example, the pyramidal portion has a sectional shape closer to a circle and the rotation preventive effect is reduced. When the number of angles of the pyramidal portion is decreased as represented by a rectangle, the rotation preventive effect is reduced by half.

[0039] In the illustrated example, the head has a circular shape in a plan view, and a cross (+)-shaped groove is formed in an upper surface of the head. A screwdriver is to be engaged with the groove when the nail is pulled out. Depending on cases, the groove may have a hexagonal, rectangular, or minus ()-like shape. The upper surface of the nail head is chamfered or rounded in some cases to be relatively lowered at its outer circumferential portion such that the hitting force is maximally concentrated to a central region.

[0040] In the illustrated example, the internal angle defining the pyramidal portion of the head, denoted by the Greek letter in FIG. 3, is 70 as mentioned above. Because of the head having an outer diameter that is to be held within a certain limited range, if the above-mentioned internal angle is too large, a difficulty would arise in forming, in the upper surface of the head, lateral portions of a groove with which a screwdriver, for example, is engaged. If the above-mentioned internal angle is too small, the length of the head would be increased and the length of the threaded portion would be reduced. For that reason, the above-mentioned internal angle is preferably set to about 60 to 80.

Example 2

[0041] FIG. 4 illustrates an embodiment slightly different from the above-described embodiment. In this embodiment, the threaded portion is divided into four parts, and the head has a circular outer outline in a plan view. The tip of the nail has a conical shape with an apex angle of 60 as in the above-described embodiment. Furthermore, the portion of the head on the back-surface side has a hexagonal pyramidal shape as in the case illustrated in FIG. 3.

[0042] In this embodiment, as illustrated in FIG. 4, the threaded portion is divided into four portions A, B, C and D, which are each in the form of a quadruple-thread screw. In the threaded portion A at the top, a lead angle is 42 and a lower-height thread ridge is formed at alternate threads of the quadruple-thread screw for volume adjustment. In the second threaded portion B, the third threaded portion C, and the fourth threaded portion D counting from the top, lead angles are all 45 and thread ridges have the same height.

[0043] In use, the threaded nail according to this embodiment is driven into a material, such as a wood material, by employing a hammer or the like. When driven, the threaded nail is forced to thrust into the material while rotating about the shank axis. The driving of the threaded nail with a hammer or the like, is performed until the head is buried in the material. FIG. 5 illustrates a state where two wood materials are fixed to each other using the threaded nail according to this embodiment. An attached material M on the upper side is fixed to a stationary material N, such as a post, by employing the impact-driven threaded nail. In the illustrated fixed state, the nail is buried into the attached material M completely, i.e., up to the upper surface of the head.

[0044] In the above fixed state, even when external force acts on the nail in the direction to rotate it, the nail is not easily rotated because the nail head having the pyramidal shape is engaged with an inner surface of a hole that is formed in the attached material by the driving of the nail. As a result, both the materials are hard to loosen. In addition, since the shank includes the multiple unthreaded shank portions, a satisfactory effect can also be obtained against external force acting in a side direction of the threaded nail, i.e., in a shearing direction.

Example 3

[0045] By modifying only the tip of the impact-driven threaded nail into a bombshell-like shape (see FIG. 9) that is optimum for being driven into a steel sheet or the like, the impact-driven threaded nail can be momentarily and firmly attached even to a steel-made underlying material, such as a C-type steel, instead of a woody underlying material, such as a wood material, with a nailing air gun capable of applying strong hitting force, insofar as the nail can be driven into the attached material. It is hence apparently possible to not only improve performance, but also greatly contribute to increasing work efficiency to a level much higher than that in attachment work in the past. The impact-driven threaded nail illustrated in FIG. 9 is used in the case where the attached material is a thin sheet with a thickness of 20 mm or less. Even in other cases, for example, where the attached material has a large thickness, similar advantageous effects to those obtained with the impact-driven threaded nail illustrated in FIG. 9 can be provided in use by modifying only the tip of each of the threaded nails, which have the shapes and the dimensions as illustrated in FIGS. 1 and 4, into a bombshell-like shape as described above.

Example 4

[0046] While the above EXAMPLES provide the impact-driven threaded nails each having the thread with the lead angle of about 45, FIG. 7 illustrates a threaded nail, generally called a screw nail, having a larger lead angle. The screw nail can be said as being one type of the so-called impact-driven threaded nail for the reason that, as mentioned in paragraph [0004], because helical ridges and grooves are formed along an outer circumference of a shank, the nail is driven into wood or the like in use, while the shank is caused to rotate, by hitting a head with a hammer, for example. However, because of having the larger lead angle, the screw nail has a problem that the nail is apt to loosen when large external force acts on the attached material in a direction to pull back the attached material from the underlying material (see paragraph [0006]). Aiming to solve such a problem, as in the above EXAMPLES 1 to 3, a portion of the head on the side nearer to the shank is formed in a pyramidal shape having a regular hexagonal cross-section with a diameter decreasing gradually toward the nail shank, whereby one type of impact-driven threaded nail, called the screw nail, having a high loosening preventive effect can be obtained. [See FIG. 8]

INDUSTRIAL APPLICABILITY

[0047] As is apparent from the above description, since the impact-driven threaded nail according to the present invention is harder to loosen than related-art various types of nails and threaded nails, it is possible to not only increase attachment strength, but also to carry out work in a manner of, as described in, e.g., paragraph [0021], successively driving and fixing many nails with the aid of an air gun, which is widely used for nailing, instead of employing a hammer or the like. Furthermore, when the impact-driven threaded nail according to the present invention is applied as in EXAMPLE described in paragraph [0036], the modified screw nails can be momentarily driven and firmly fixed using the air gun. It is hence apparent that the impact-driven threaded nail according to the present invention exhibits very good characteristics and can be effectively used in various fields, such as wood working and building.

REFERENCE SIGNS LIST

[0048] 1 impact-driven threaded nail [0049] 2 shank [0050] 3 head [0051] 4 tip [0052] 5 threaded portion [0053] 6 unthreaded shank portion [0054] 7 pyramidal portion on back-surface side of head (tapered portion) [0055] A part of threaded portion 5 on head side [0056] B part of threaded portion 5 other than A [0057] M attached material [0058] N stationary material such as post [0059] a plan view [0060] b front view [0061] c side view [0062] d sectional view [0063] angle of sloping flank on head side in FIG. 2; 45 [0064] angle of sloping flank on tip side in FIG. 2; 15 [0065] internal angle defining tapered portion of head on back-surface side; 70