The present invention relates to an invisible connection for faced parts, in particular for furniture of wood or chipboard, involving use of adhesive and a connecting member. In such a connection the adhesive is introduced in fluid form or in the form of a paste into cylindrical boreholes in the parts to be connected and the connecting member is driven or pressed at each of its two ends into the boreholes. The connecting member has a form which is symmetrical about its axial mid-point and is provided with one or more longitudinally extending grooves and annular notches and/or other profiling on the outside of the member and each of the two end faces of the connecting member is formed so as to extend to a point or each has a point. The term "invisible connection" as used herein refers to a connection which is not apparent to the eye, at least when the joined-together parts are viewed.
For the invisible connection of faced parts in furniture, for example for the right-angled connection of a side wall of the body of an article of furniture to the floor of the article, a multiplicity of connecting members are known. These connecting members are introduced into prepared cylindrical bores in the parts to be connected. For improving the rigidity, a fluid or pasty material with gluing or adhering and/or foaming up properties is introduced into the cylindrical bore before the introduction of the connecting member. This introduction of the adhesive is time consuming and requires a high degree of care. Soiling of the surfaces of the faced parts cannot be avoided. An exact dosage of the quantity of the adhesive required for each borehole is necessary, but this cannot be brought about without waste. The adhesive introduced into the borehole is forced principally against the end wall of the borehole and in part into the chipboard by the connecting member when it is introduced. A uniform distribution of the adhesive over the length of the connecting member does not take place. After the introduction of the adhesive the making of the connection must take place in a relatively short time, since otherwise a hardening of the adhesive will occur.
The preparation of this connection requires knowledge in a special field. Therefore, in the case of later assembled furniture parts, for example after transport of the furniture parts on pallets in order to save space, connection of the faced parts is not carried out by use of an adhesive in combination with connecting members introduced into the cylindrical boreholes, but in general a problem free screw connection is used. This screw connection is adequate enough from the technical point of view but not however from the aesthetic point of view, since it remains visible and is thereby prejudicial to the appearance of the furniture.
In order to achieve an interference fit, the diameter of the connecting member is slightly greater than the diameter of the borehole. The connecting member must be driven or pressed into the borehole in each case in order to produce a secure and fully close connection between the parts. In this it cannot be excluded that a forcing out of adhesive material may occur at the outer edge of the borehole.
It is an object of the present invention to provide an invisible connection of the kind described above, in which the adhesive is introduced into the boreholes in the precise dosage required with little waste and without danger of soiling the surfaces of the parts to be connected, and in which the making of the connection is not tied in time to the introduction of the adhesive, a uniform distribution of the adhesive over the length of the connecting member being achieved and the connecting means being formed so that no press tool or driving tool is necessary for its introduction into the borehole in achieving an extremely rapid and secure connection between the parts.