EXPANSION NAILS,EXPANDING AT ONE OR MORE PLACES AFTER BEING DRIVEN IN

Abstract: Nail (1) for joining two or more pieces (4, 5) of wood, board or other porous or soft material. The nail strengthens the joint by expanding at one or more places inside the material when being driven in which is achieved by the nail having one or more longitudinal, local slits (2) of which preferably at least one at a pointed portion (3) of the nail. Each slit is on either side defined by portions being slightly bent outwards and capable of bulging further outwardly without rupture. When the nail (1) has been driven to its final position further blows atone of the ends of the nail and using a suitable hold-up tool (6) the side portions of the slit expand by further bulging and simultaneously the length of the nail is shortened.

Description: Expansion nails, expanding at one or more places after being driven in. In joining two or more sections or parts of wood or other similar porous or compressable material bγ_ means of nailed joints, it is often desirable to reinforce the joint as far as possible in such a way that the parts are pre¬ vented from separating from each other. The simplest way of floing this so far has been to select the nails sufficiently long so that when driven in they completely penetrate all the parts to be joined so that the tips of the nails project from the opposite side to that of the nail head, the tip thereafter being bent to one side with a couple of blows and then knocked down into the surface of the material. This method is indeed simple but has several disadvantages. For example, it is sometimes not so easy to get at the nail tip for knocking it sideways. The surface of the material is also easily damaged, and it is difficult to recess the nail tip in the material, resulting in that the appearance of the finished joint is not particularly good. The disadvantages and drawbacks mentioned above are substantially avoided by means of the present invention, which relates to a nail able to expand at one or more places after being driven in, especially in the vicinity of its ends, into the material in which it has been driven, The expansion or . expansions take place through further blows on the nail in its axial direct¬ ion while using a hold-up tool, preferably of metal. This expansion is enabled by the nail having longitudinal slits along certain parts of its length, preferably at the end portions where the material on either side of the slit is bent outwards somewhat to enable the initiation of the outward bulge of the nail material on either side of the slit when the nail is sub¬ jected to further blows after having been driven in place, causing the nail ends to be displaced in towards the centre of the nail, the nail length suitably being adjusted so that the tip finishes up somewhat inside the outer surface of the material, or at least flush therewith. The nature of the nail made in accordance with the invention is apparent in closer detail from the appended claims. An embodiment example of a nail in accodance with the invention will be de¬ scribed below in detail with reference to an accompanying drawing where the Figure 1a. shows the nail in its entirety, seen from one side, and Figure 1 the lower portion of said nail to a somewhat larger scale. Figures 2 a, b, c and d show in section four different states of the nail in the process o making a joint in two pieces of wood, using a metal hold-up tool. Figure ~ \ shows the nail after being driven in, but before-deformation of the expans portions, and Figure 3b shows the appearance of the nail after deformation of the expansion portions, using two metal hold-up tools. It is to be understood that the invention is not limited solely to what is apparent from the embodiment example, but all kinds of different modificat ions can be envisaged within the scope of the invention. In the drawing figures, the numeral 1 denotes the nail body, made with a four-sided section in a conventional steel quality, which is thus relative easily deformable. The numeral 2 denotes the slit with the material on either side thereof having slightly outwardly curved sides, and 3 denotes the tips. In many cases it is of great advantage to make the nail symmetri ally with the tips and and slits at both ends, since it then is not necess to pay attention to what end of the nail is to be driven in, which is an advantage, especially with automatic processes using a nailing pistol or t like, for example. I Figures 2 and 3, the numerals k and 5 denote two piec of wood which are to be joined by means of a nailed joint in accordance wi the invention, a hold-up tool 6 in the form of relatively large metal plat being used. In Figures 2 a, b, c and d only one plate 6 is used, this being the hold-u plate, the nail being knocked in from its end facing from the plate until this end has completely gone into the material , In Figures 3 a and b is shown how the tips can be pressed into the material and 5 using blows or pressure and with the aid of two driving plates 6, expansion being obtaine at the slits at the same time, these expansions penetrating into the mater at both sides, resulting in positive retention of the pieces and 5 y means of the nailed joint.

Claims: Claims 1. Expansion nail, expanding at one or more places after being driven in, characterized in the nail having one or more local longitudinal slits (2) end, of which preferably at least one at a pointedyportion (3) of the nail, said slit or slits (2) on either side being defined by portions being slightly bent outwards and capable of bulging further outwardly without rupture when the nail, after having been driven mainly to its intended final position in a relatively soft material (*t, 5) such as wood, board or the like, is sub¬ jected to further blows axially at one of its ends using a suitable hold-up (6), the side portions of the slits (2) expanding by further bulging and simultaneous shortening of the nail length. 2. Nail according to claim 1, characterized in the nail having slits (2) at both end portions, said portions preferably being pointed. 3. Nail according to claim 1 or 2, characterized in the nail having a mainly four-sided section. . Nail according to any preceding claim, characterized in the length of a slit (2) being of the order of k times the nail diameter.

Inventors: BILLING L
Applicants: BILLING L
Application year: 1979
Main classification: F16B19
IPC codes: F16B15