NAIL

Abstract: A nail (21) for foamed concrete or similar materials is proposed. The nail comprises a nail body having a head (23) and a leg (22), and a leg opener (31). The leg is divided into a pair of leg sections (25) spaced by a slit (24). The leg opener (31) has a washer (34), a wedge guide (32) and a wedge (33). The leg opener is put on the nail body from its tip and the assembly of the nail body and the leg opener is driven to secure an object to foamed concrete. The leg sections are opened by the wedge into opposite directions as the nail body goes into the foamed concrete.

Description: The present invention relates to a nail, particularly to a nail of a leg-open type used to secure an object to foamed (or autoclaved lightweight) concrete, heat-insulating material, etc. Since such materials do not have restoring elasticity, a special fastener is needed to secure an object to such a material. Figs. 6 and 7 show examples of conventional fastener used with foamed concrete, heat-insulating material and similar materials (hereinafter referred to as foamed concrete). Fig. 6 shows a tapered nail 11 having four tapering sides. When driven into the material, it compresses foamed concrete with their tapering sides. This increases the frictional resistance between the nail and the foamed concrete and provides a resistance to getting-off or removal. This conventional nail loosens and gets off easily when subjected to vibration, because it resorts merely to the frictional resistance between the nail and the foamed concrete to maintain the resistance to removal. Fig. 7 shows an anchor 13 made of synthetic resin and adapted to be driven into a hole formed in the foamed concrete. The anchor is formed with a hole 14 to receive a nail. For use of this anchor, a hole has to be formed beforehand in the foamed concrete. This is very incon­ venient and requires a special tool for forming the hole. An object of the present invention is to provide a nail which provides a sufficient strength to resist the pulling force merely by driving it into the material. In accordance with the present invention, there is provided a nail comprising a nail body and a leg opening member, the nail body having a head and a leg integral with the head, the leg being divided into a plurality of leg sections spaced by a slit extending axially there­ between, the leg sections having their ends tapered at their tip and being coupled together by a breakable portion provided at a distance from the tip of the leg sections, the leg opening member having a wedge guide having such a thickness as to be received in the slit, a washer in the form of a ring formed at one end of the wedge guide and a wedge formed at the other end of the wedge guide and having a pair of tapered surfaces of such a shape as to be received between the tapered ends of the leg sections, the washer being adapted to be put on the leg of the nail hody, the breakable portion having such a strength as to be broken by the upper edge of the wedge guide when the nail is further driven even after the upper edge of the wedge guide has butted the breakable portion. Other objects and features of the present invention will become apparent from the following description taken with reference to the accompanying drawings, in which: Fig. 1 is an exploded perspective view of the nail embodying the present invention; Fig. 2 is a vertical sectional front view of the nail half-driven; Fig. 3 is an enlarged horizontal sectional plan view of the nail taken along the line III - III of Fig. 2; Fig. 4 is a vertical sectional side view of the nail half-driven; Fig. 5 is a vertical sectional front view showing the nail fully driven; Fig. 6 is a perspective view of a conventional nail; and Fig. 7 is a perspective view of an anchor used in a conventional fastener. Referring to Fig. 1, the nail according to the present invention comprises a nail body 21, and a leg-­ opener 31 adapted to be put on the tip of the nail body 21. The nail body 21 has a head 23 and a leg 22 divided into a pair of leg sections 25 by a slit 24 extending axially from the tip of the nail to the head 23. Each leg section 25 has a tapered surface 26 facing inwardly at its tip. The leg sections 25 are coupled together by a plurality of breakable portions 27 in the form of thin rods disposed in the slit 24. The leg opener 31 has a wedge guide 32 in the form of a plate having such a thickness as to be received in the slit 24 and a width substantially equal to the diameter of the leg 22, a ring-shaped washer 34 formed at one end of the wedge guide 32, and a wedge 33 formed at the other end thereof. The leg opener 31 is formed as an integral unit. The wedge 33 has a pair of tapered surfaces so as to be snugly received between the tapered surfaces 26 on the leg sections 25, as shown in Fig. 2, when the leg opener 31 is put on the tip of the nail body 21. Referring to Fig. 3, each of the leg sections 25 is formed with a projection 28 extending axially and the wedge 33 of the leg opener 31 is formed with a pair of grooves 35 extending axially to receive the projections 28 on the leg sections 25. This facilitates positioning of the leg opener 31 with respect to the nail body 21 and serves to guide the axial movement of the former relative to the latter. The breakable portions 27 on the nail body 21 serve to position the leg opener 31 with respect to the nail body 21 and to connect the leg sections 25 together, thus preventing the leg portions from bending or getting apart from each other during various processings. The breakable portions 27 are formed to have such a strength as to bear the pressure transmitted from the foamed concrete through the wedge guide 32 during an initial stage of nail driving and to be broken by the upper edge of the wedge guide 32 when the nail is driven further after the washer 34 has butted against a part 42 to be secured, as shown in Figs. 2 and 4. In the preferred embodiment, three breakable portions 27 are provided, but there is no intention of limiting the number of the portions to three. The upper edge of the wedge guide 32 is formed with a V-shaped recess 36 to contain the broken pieces of the breakable portions 27. The portions 27 may be either integrally formed with the leg portions 25 or formed as separate members of metal or synthetic resin inserted into transverse holes formed in the leg sections 25. In use, firstly, the leg opener 31 is set on the nail body 21 by inserting the leg sections 25 into the hole in the washer 34 with the wedge guide 32 in the slit 24 of the nail body 21 until the upper edge of the wedge guide 32 butts the lowermost breakable rod 27. In order to secure an object 42 to foamed concrete, the leg 22 of the nail body 21 with the leg opener 31 is driven into foamed concrete 41 through a hole 43 formed in the object 42 to be secured. At the initial stage of driving, the pressure applied to the wedge 33 of the leg opener 31 is borne by the breakable portion 27 through the wedge guide 32. Therefore, the leg sections 25 advance straightly into the foamed concrete without opening until the washer 34 butts the object 42 to be secured, as shown in Figs. 2 and 4. When the driving of the nail is continued even after the washer 34 has butted the object 42, the breakable portions 27 will be broken one after another by the wedge guide 32. As only the nail body 21 goes further into the foamed concrete, the leg sections 25 will be forced to open by the wedge 33 of the leg opener 31 as shown in Fig. 5, because the leg opener cannot move further. In so functioning, the tapered surfaces on the wedge 33 serve as a guide for guiding the leg sections 25 in opposite directions. While the nail is being driven, the foamed concrete between the leg sections is fully compressed by the wedge 33 and the leg sections 25. The wedge 33 and the compressed foamed concrete between the leg sections 25 serve to prevent the leg sections 25 from restoring to their original positions. This assures a high resistance to pulling-off force applied to the nail. Fig. 5 shows a final state in which the nail is completely driven with its head 23 on the washer 34. Now, the object 42 is firmly secured to the foamed concrete.

Claims: 1. A nail comprising a nail body and a leg opening member, said nail having a head and a leg integral with said head, said leg being divided into a plurality of leg sections spaced by a slit extending axially there­ between, said leg sections having their inner surfaces tapered at their tip and being coupled together by a breakable portion provided at a distance from the tip of said leg sections, said leg opening member having a wedge guide having such a thickness as to be received in said slit, a washer in the form of a ring formed at one end of said wedge guide and a wedge formed at the other end of said wedge guide and having a pair of tapered surfaces of such a shape as to be received between said tapered surfaces of said leg sections, said washer being adapted to be put on said leg of said nail body, said breakable portion having such a strength as to be broken by the upper edge of said wedge guide when the nail is further driven even after the upper edge of said wedge guide has butted said breakable portion. 2. The nail as claimed in claim 1, wherein said breakable portion is integral with said nail body and is formed in the form of a thin rod. 3. The nail as claimed in claim 1, wherein said leg opening member comprising said wedge guide, said washer and said wedge is an integral member. 4. The nail as claimed in claim 1, wherein one of said tapered surfaces on said leg sections and said tapered surfaces on said wedge are formed with an axial projection, and the other are formed with an axial groove to receive said axial projection.

Inventors: IKUTA, KAZUICHI C/O WAKAI & CO., LTD., KAJI, KATSUJI C/O WAKAI & CO., LTD., YAMAMOTO, EIJI C/O WAKAI & CO., LTD., Ikuta, Kazuichi c/o Wakai &amp; Co., Ltd., Kaji, Katsuji c/o Wakai &amp; Co., Ltd., Yamamoto, Eiji c/o Wakai &amp; Co., Ltd.
Applicants: WAKAI & CO. LTD.
Application year: 1986
Main classification: F16B15
IPC codes: F16B15