WO1997015761A1

WO1997015761A1 - Improvements in or relating to a fastening element

Info

Publication number: WO1997015761A1
Application number: PCT/SE1996/001351
Authority: WO
Inventors: Lars Eriksson
Original assignee: Lars Eriksson
Priority date: 1995-10-23
Filing date: 1996-10-22
Publication date: 1997-05-01
Also published as: SE9503714D0

Abstract

The invention refers to improvements in or relating to a fastening element which can be sheet formed or have the form of a tap or a plug for assembling details (13) especially within the joinery line of business and said fastening element is intended to cooperate with at least one cavity (5) in at least one of the details which shall or have been assembled. The outside (4) of the fastening element (1) comprises a great number of projections (7, 8, 8', 10) situated close to each other in the longitudinal direction of the fastening element, said projections after the mounting of the fastening element in the cavities (5) exert a pressure against the mantle surface of respective cavity (5) which results in that it remains undeformed at the same time as a totally play free joint between the details is maintained.

Description

improvements in or relating to a fastening element

Tne present invention relates co improvements m or relating to a fastening element, said element is sheet formed or has tne form of a pm or piug and is mtended to oe used to ηoin details together, particularly icnin the joinery line of business and said fastening element s provided to cooperate witn at least one cavity at least one of the details intended to be or have been joined together.

Today a joint of different details within the furniture industry can occur in the following way. The details which shall be joined together show or are provided with pre- drilled holes or milled-out slots. When a furniture shall be made having two vertical sides and two horisontal sides those holes provided at the top can be made vertical in the vertical sides and also in the horisontal sides in order to coincide with the first ones. Before joining e.g. pins with adhesive are pushed into the holes in one of the sides. The pins have a length which is longer than the depth of the holes so as to protrude a distance which is nearly the same as the depth of the hole in the other side. Thereafter the other side is pressed against the first side, so that the other part ot the pins which also has been provided with adhesive protrudes into the holes in the other side, where¬ upon the sides are pushed together, so that they are lying tightly against each other. When the adhesive has dried the joint is finished.

These center pins are normally made of wood in different lengths and thicknesses and are mostly round formed, viewed in section. Beech, birch or another kind of wood are used. The manufacturing is made in such a way that the wood material is cut into rounded rods. They are ornamented along their mantle surface with deformating influence on the surface fibres so that grooves are formed. Thereafter the pins are dried. The grooves are used for receiving adhesive during joining together the joineries. When the adhesive is sucked into the surface of the pins they expand and especially in the region at the grooves, whereby a better filling up of the holes is achieved at the same time as a rigid and anti-twist joint is obtained as a result. However there must not be a play between the hole and the pin, because in that way the joint will not be perfect.

Today there also exsists plugs intended for joining details, said plugs are provided with protruding pegs, flanges and projections. All these items use the principle that the plug during insertion has protruding elements which do not fail. When you are trying to disassemble parts joined together by aid of this plug the protruding portions will grasp the mantle surface of the hole and to give rise to a bursting effect so that the surrounding of the hole can split. During this grasping a deformation occurs of the mantle surface of the hole, so that before the protruding parts have hooked-up firmly against the mantle surface a small movement has already taken place and this deformation causes that the details, which are going to be joined together with the plug, will be fixed into each other with a too great play. This is not acceptable. These previously known plugs must be very exact in their dimensions, in that too big grooves will easily destroy the walls of the hole.

The purpose with the present invention is to provide improvements in or relating to a fastening element of the kind mentioned in the beginning by aid of which the problems mentioned above are eliminated. The distinguishing features of the invention are set forth in the following claims.

Thanks to the invention a fastening element has now been provided which in an excellent way fulfils its purposes at the same time as it is easy and cheep to manufacture. By manufacturing the fastening element in a material which is possible to cast or mould you can form fastening elements so that they have those special means which actively cause that you attain the advantages desired. The fastening element according to the invention does not need to have an exact dimension relative to that or those cavities exsisting in at least one of the actual details which shall be joined together, in order to obtain the stability desired in the joints. During mounting of a softer material by using the plug according to the invention no damage of the holes will happen which in contrary will be the fact by the plugs previously known with permanent, non-resilent protrusions or pegs. Fastening elements can be cast in plastic, zinc, aluminium or any else suitable material, where the flanges are resilent. They shall be enough thin, since stiffer material requires thinner flanges or pegs.

The invention will now be described closer in detail below in view of the accompanying drawings by aid of some preferable embodiments, in which

Fig. 1 shows a fastening element in the form of a peg or plug according to a first embodiment of the invention,

Fig. 2 shows a fastening element according to a second embodiment of the invention,

Fig. 3 shows a schematic perspective view of how the mounting of the fastening element in the form of center pegs according to the invention looks like,

Fig. 4 shows a schematic perspective side view in section of a third embodiment of the invention,

Fig. 5 shows a schematic side view in section of a fourth embodiment of the invention,

Fig. 6,6' show a side view of a fifth and sixth embodiment of the invention respectively,

Fig. 7 shows a further embodiment according to the invention, where the fastening element is formed as a sheet element,

Fig. 8 shows a perspective view of still a further embodiment according to the invention, where a sheet element has an angled portion at one of the parts which shall be joined together and Fig. 9,9' show a side view and an end view respectively, of an embodiment, where there are projections only on the one half.

As can be seen from the drawings and more definitely of the embodiment according to the invention illustrated in Fig.l and 2 the fastening element, in this case in the form of a cener peg or plug l, consists of an elongated cylinder formed portion with a given length 2 and diameter 3. The plug 1 is intended to be inserted into cavities 5 made in those respective details which shall be joined together. The outer surface or mantle surface 4 of the plug is treated, so that different features are given to the plug 1. The mantle surface 4 is provided with projections 7 arranged closely to each other, said projections can have the form of jags, lips or wings. According to the embodiment illustrated in Fig. 2, 6 and 6' the projections of the plug 1 have the form of elongated flanges or tongue formations 8,8'. he projections 7, 8, 8' shall be able to bend when the plug l is inserted into the cavities 5. The diameter of the plug 1 must in other regions be so exact that it can be knocked into the cavities 5. A play can be accepted but the fitting must be good. However one can in this case accept some less good play than when using ordinary center taps by wood. The projections 7, 8, 8' protrude a bit outside the mantle surface 4 and describe together a bigger diameter than that one which the other mantle surface delimits. The projections 7, 8, 8', 10 comprise preferable of such a great number and so tightly lying elements that they do not provide such a great pressure against the mantle surface of a cavity 5 that its wall is deformated. At the embodiments according to Fig. 2 and 6 the mantle surface 4 can include at least one cavity 6, in which the projections 7, 8, 8' 10 are arranged but these can of course also be arranged directly protruding from the outside or mantle surface 4 of the fastening element 1, as illustrated in Fig. 6' .

When the tap l is inserted into the cavities 5 the projections 7, 8, 8' and 10 are folded, which also is the case with the embodiments according to Fig. 4 and 5, when said projections abut against the walls 9 of the cavities 5. If the projections are situated in a shallow cavity 11 they are folded more than if they are placed in a deeper cavity. The flexibility against the walls of the cavities 5 will also be greater in the shallower cavity. If the projections are placed in a deeper cavity the angle will be smaller and the flexibility against the walls 9 smaller, whereby the locking play will also be greater.

The alternative using shallower cavity 5 makes that the plug according to the invention is fixed better in the cavities 5. During experiments to pull out the plug the projections will arise, so that the friction will increase against the walls 9. If you pull further the pressure against the walls 9 will increase and you will get a locking effect which makes that the plug 1 will stay in position in the cavities 5. By determine the length of the projections 10, the depth of the cavities 11, 12 and the length of the protruding of the projections 10 outside the mantle surface 4, the right loocking of the plug 1 can be provided in order to get the optimal joint of the joinery details 13 (Fig. 3) .

If you would like to make the joint stronger the plug could be filled by adhesive 14. An indication of fracture 15 somewhere on the mantle surface of the projections 10 can cause that the mantle surface leaks out adhesive through openings 16 during the assembling of the details 13 (Fig. 3) . This can e.g. be arranged at the base portion 17 of the projections. During folding of these projections 10 ruptures at the indication of fracture 15 can cause the opening 16 so that adhesive leaks out, see Fig. 5.

In order to better guide the mantle surface 4 in a direction towards the cavity walls 9 it can be provided with extra projections 18 in parallel with its length or eventually in right angle to its length and around the mantle surface as can be seen from Fig. 5. These projections 18 would be able to cut into a certain distance in the cavity walls 9 during the insertion operation of the plugs 1 into the cavities 5 without that play occurs so that friction and guiding helps to increase the precision and the stability during the assembling operation. In this way the plug 1 cannot so easy turn around its axis, whereby the projections 7, 8, 8' and 10 do not tilt in another direction than that one in the pulling direction 19.

The projections 7, 8, 8' and 10 can be serrated in the top so that they in a better way grasp the walls 9 of the cavity 5 since these often are a bit rough in the surface without that friction will arise. If the surface of the walls 9 are a bit rugged these serrations will be of special use. If stiff material is used in the projections they are made thin and the then will get a certain flexibility so that they will not cause a deformation during insertion into the cavities 5. The projections 7, 8, 8' and 10 are situated in the bottom of the cavities 6 and will therefore have a predetermined length which can be adjusted to its stiffness which depends on the stiffness of the material and the thickness of the material in order to get a wanted loocking effect against the walls 9.

Such a plug or center tap 1 described above will be essen¬ tially cheeper to make than those now exsisting wood taps on the market. All problems mentioned above namely material loss, treatment, sorting, crack formations should disappear. The problems with gluing would totally disappear if one finds it satisfactory only to use plugs not filled with adhesive. If you should like to use plugs 1 filled with adhesive you would in any cases achieve a correct dose at the right place. All handling with adhesive application disappears and you can work in such a way that adhesive should not be used.

In Fig. 6 an embodiment of a fastening element in the form of a plug 1 is illustrated, said plug comprises in its cavities 6 a great number of projections 8' situated after and closely to each other. Furhter the end portions of the plug 1 can be bevelled in order to inserted easier into the cavities 5 of those details 13 which will be assembled. To contain as many projections as possible in the cavities 6 they are situated in a distance from each other in the longitudinal direction of the fastening element which is smaller than three times of each material thickness of respective projection. Hereby a pressure is provided against the mantle surface or the wall 9 of the cavity 5, which causes that it remains nearly undeformed at the same time as an almost play free joint between the details 13 is main¬ tained. The embodiment illustrated in Fig. 6' is on the whole similar to that illustrated in Fig. 6 but it lacks the cavities 6. Here the projections 8' are formed directly protruding from the outside or mantle surface 4 of the plug 1.

In Fig. 7 an embodiment of the fastening element 1 is illustrated when it is sheet formed, in which the cavities 6 comprise one projection 8' each in the form of elongated flanges having a predetermined length and extension.

In Fig. 8 a T-formed fastening element 1 is illustrated in the form of e.g. an edge lining which is fixable by aid of a suitable profile around a sheet member, e.g. a particle board. Here the sheet formed portion of the fastening element 1 having a prodruding projection 8' in a cavity 6 insertable into a cavity made in a second detail 13 after assembling of the angle formation to a first detail 13. The projections function and can look like some or any of the other projections in the other figures together with the corresponding cavities 6.

In Fig. 9 and 9' finally an embodiment of the fastening element is illustrated when it is formed with the projec¬ tions 8' on its one half and where the other half 20 lacks projections. Sometimes a fastening element is needed which is fixed by aid of its projections 8' in a cavity 5 while the other half 20 without projections can be used only to guide in the cavity 5, so that a disassembling can be done for removal.

All embodiments according to the invention are made so that the number of projections in the form of taps and flanges are so great and are placed so tightly that no pressure of importance bears against the walls of the mantle surface in the cavity or cavities. The great number of projections also distributes the pressure against respective mantle surface of the cavity, so that only a small and preferable a permanent pressure exsists. During stresses against the center tap or plug therefore no deformation of any note arises of the material of the mantle surface.

The invention can be used without having the flanges or taps 7, 8, 8', 10 situated in a cavity 6, 11, 17. Anyhow these flanges or taps protrude beyond the outside or mantle surface 4 of the plug 1 in order to be bent backwards during insertion into the cavities 5. Then the flanges function as the active diameter, which guides the plug.

Claims

Cl aims

1. Improvements in or relating to a fastening element (1) , which can be sheet formed or having a form like tap or plug and which is intended to assemble details (13) especially within the joinery line of business and said fastening element is intended to cooperate with at least one cavity (5) in at least one of those details, which shall or have been joined together, characterized in that the outside (4) of the fastening element (1) comprises a number of projections (7,8,8', 10) arranged closely to each other, which after the mounting of the fastening element (1) into the cavities (5) cooperating with the same are intended to exert a pressure against the mantle surface or wall of the respective cavity (5) which results in that it remains mainly undeformed at the same time as an almost totally play free joint between these details (13) is maintained.

2. Improvement as claimed in claim 1, characterized in that cavities (6) for the projections (7, 8, 8'10) are arranged in points in and/or are formed around the outside (4) of the fastening element (1) along its longitudinal direction.

3. Improvement as claimed in claim 2, characterized in that the cavities (6) have a depth and an extension around the projections (7,8,8',10), which permits a bending of the projections laterally and that their outer portion mainly lies in level with the outside (4) of the fastening element (1) .

4. Improvement as claimed in claim 1, characterized in that the projectoins consist of elongated flanges or tongue- formations (8,8'), which extend integrally or continuously around the outside (4) of the fastening element (1) .

5. Improvement as claimed in claim 4, characterized in that respective cavity (6) comprises a great number of continuously extending flanges (8,8') along the longitudinal direction of the fastening element (1) , said flanges are arranged in parallel after each other and at a predetermined distance closely to each other.

6. Improvement as claimed in claim 4, characterized in that the projections (7,8,8' ,10) are situated at a distance from each other in the longitudinal direction of the fastening element (1) which is smaller than three times the material thickness of each projection.

7. Improvement as claimed in claim 4, characterized in that the elongated flanges (8,8') extend in a helical form around the outside (4) of the fastening element (l) along portions of or along the whole outside (4) .

8. Improvement as claimed in claim 4, characterized in that the flanges (8,8') are arranged in cavities (6) extending around the fastening element (1) in the form of groove formations.

9. Improvement as claimed in any of the preceding claims, characterized in that the fastening element (1) wholly or partly is filled with adhesive (14), which leaks out at indications of fracture (15) along the projections (7, 8, 8',10) and which are created when bending of the projections during the insertion of the fastening element (1) into at least one of the cavities (5) .