PLUG

Abstract: The invention relates to a plug for joining of for example wooden details in furniture. It is characterized in that it consists of a firm core (1) having recesses (2) and a solid adhesive (4) surrounding the core which adhesive has a high mechanical strength and which is anchored in the core (1).

Description: PLUG TECHNICAL FIELD: The present invention relates to a plug for joining different parts, for example wooden parts. Such plugs have an extended field of use but are especially much used in the furniture industry for joining different details in furniture made of wood. BACKGROUND OF THE INVENTION: Plugs, especially within the furniture industry, are usually made of wood. They generally have a circular section for filling up a circular bore hole in the details that are to be joined. The plugs have most often been made with a very narrow marginal so that they have to be punched in. A certain elasticity is then required of the plug and/or the surrounding material. It can for many purposes be sufficient to punch in a plug to get a sufficiently good joining of the details that are to be joined but most often the plug has to be dipped in a glue before the joining or the hole is provided with a glue. The reason for this is of course that the plug shall not as time goes on, loosen. If a glue is used it is therefore important that this glue or adhesive has a good adhesion to both the plug and the surrounding material. This usually means that the plug and the surrounding material must be made of the same or a similar kind of material so that the adhesive adheres equally to both materials. This means accordingly a limiting of the material from which the plug can be made which within the furniture industry means that it will mainly be a question of wooden plugs. TECHNICAL PROBLEM: The above plugs have been well tested and fulfils in most cases their tasks. It can, however, for different reasons be desirable to use a plug of another material than the one that shall surround the plug. The reason for this can be that one needs a greater strength or flexibility of the plug or that it has to be manufactured in greater series of a cheaper material such as plastics. The problem that then will arise is that the adhesive which one has to use does not have the same adhesion to the plug as to the surrounding material of the plug. A conventional plug with a conventional glue would therefore as time goes on probably loosen. THE SOLUTION: It has therefore long been a desire to be able to solve the above mentioned problems with plugs, adhesives and surrounding material and according to the invention one has therefore brought about a plug for joining of for example wooden details which is characterized in that it consists of a firm core having recesses and a around the core, meltable or in a solvent solvable adhesive in solid shape and with a high mechanical strength and which has been anchored in the core and has a good adhesion to the surrounding material of the plug, whereas the surface layer of the adhesive is intended to be melted or solved during the joining. According to the invention the core can suitably consist of plastics, metal, for instance steel or wood. It is according to the invention suitable that the core in section has the shape of a cross and the recesses have been made in the wings of the cross. A suitable adhesive according to the invention is one which is soluble in water or organic solvents. The meltable adhesive can according to the invention consist of bone glue or a multiple component glue of resins or the like. DESCRIPTION OF THE EMBODIMENTS: The invention will in the following be described more in detail in connection with the attached drawings where. Fig. 1 shows a plug in sideview and having one half provided with adhesive and where Fig. 2 shows the plug with adhesive seen from one end. PREFERRED EMBODIMENT: The plug according to the present invention consists of a core 1. This has been provided with recesses 2. These recesses 2 can be made in different ways. The demand to these is only that they shall have a good mechanical anchoring for the adhesive that is to be filled in the recesses 2. The plug is in the present case made in the shape of a cross which is better shown in Fig. 2. It has plain end surfaces but the edges 3 on the wings of the cross have been made oblique to facilitate the insertion of the plug in a hole. The plug does neither have to be made in the shape of a cross, it can for example be round, having radial recesses on suitable locations. As a hole not necessarily have to be bored and round the plug can of course also have a quite other shape in section as the one shown so that it fits in the hole. At the right side of Fig. 1 it is shown how the adhesive material 4 is put on the plug. The same appears from Fig. 2. As clearly appears all the recesses of the plug have been filled with adhesives. The adhesive that is used should be a such one that has a good adhesion to the surrounding material. This is more important than that it has a good adhesion to the plug as the adhesive is mechanically anchored in the plug. One condition to get a desired result is therefore that the adhesive 4 has a certain mechanical strength so that it is not mechanically destroyed at stresses. A great number of such adhesives is known before and one within the furniture industry much used adhesive namely bone glue can be mentioned as a suitable one. Other meltable or curable adhesives made on the basis of multiple components of resins can also be mentioned. The demand is only that it shall have a good adhesion to the surrounding material and have sufficient mechanical strength so that it is not destroyed on the core of the plug 1. The plug according to the invention is suitably manufactured by a so called double moulding technique. This means that one first moulds the core whereupon the adhesive in a second step is moulded on the core without removing this from its mould. This technique is known per se and is therefore not described in detail here. A presumption that the plug shall be able to be manufactured in this way is therefore that the adhesive is meltable or that it is flowable by containing some solvent or has been mixed with some agent which gives it a solid consistency during or after the moulding for example a hardener in a resin glue. When the plug is to be used it is simply dipped in a suitable solvent which can be water or an organic solvent so that the surface layer on the adhesive is solved whereupon the plug is punched into the cavity where it shall remain. For some adhesives one can instead of using a solvent heat the plug to some extent. The invention is not limited to the embodiment example shown but can be varied in different ways within the scope of the claims.

Claims: CLAIMS: 1. Plug for joining of for example wooden parts, c h a r a c t e r i z e d in that it consists of a firm core (1) having recesses (2) and a meltable or in a solvent soluble adhesive (4) surrounding the core, which adhesive is in a solid shape and has high mechanical strength and which is anchored in the core (1) and has a good adhesion to the surrounding material of the plug, the surface layer of the adhesive being intended to be melted or solved during the joining. 2. Plug according to claim 1, c h a r a c t e r i z e d in that the core (1) consists of plastics, metal or wood. 3. Plug according to any of the claims 1 or 2, c h a r a c t e r i z e d in that the core (1) has in section the shape of a cross. 4. Plug according to claim 3, c h a r a c t e r i z e d in that recesses (2) have been made in the wings of the cross. 5. Plug according to any of the claims 1-4, c h a r a c t e r i z e d in that the adhesive is soluble in water or in organic solvents. 6. Plug according to any of the claims 1-5, c h a r a c t e r i z e d in that the adhesive consists of bone glue, multiple components glue of resins or the like.

Inventors: FRIBORG ANDERS, FRIBORG SVEN, FRIBORG, ANDERS, FRIBORG, SVEN
Applicants: GISLAVEDS FORMPLAST AB
Application year: 1993
Main classification: F16B13
IPC codes: F16B11, F16B19