Connection for furniture frame parts, particularly office furniture

A furniture frame includes a first frame part with a dowel extending beyond the end thereof into an opening in a second frame part. A securing screw is provided in the second frame part at right-angles to the dowel axis. When the screw is tightened, two abutting surfaces inclined at an angle to the central plane of the dowel are pressed against corresponding, inclined surfaces in the opening. A releasable, but nevertheless very rigid connection of the various elements is thus achieved.

The invention relates to an improved connection for frame parts of 
furniture. 
In a known furniture connection arrangement, one frame part provides the 
female half of the connection and has a cylindrical zone in the center of 
said female half which opens conically to each side. The male half of the 
connection is provided on another frame part and comprises a dowel which 
is cylindrical at its outer end and conical at the base. A threaded bore 
extends longitudinally through the dowel. A plug, corresponding in form to 
the dowel, is fitted into the other side of the female half. The plug has 
a hole throughout which aligns with the threaded bore in the dowel. A 
connecting screw is inserted through the hole in the plug into the 
threaded bore in the dowel, and a secure connection of the two frame parts 
is achieved by tightening the screw. On tightening the screw, the first 
frame part is drawn firmly against the side surface of the second frame 
part. 
A disadvantage of this known connection is the fact that it is difficult to 
adjoin several frame parts continuously because access to the securing 
screws is prevented. 
The purpose of the present invention is to so construct a connection that, 
on the one hand, a quick and reliable connection between the various frame 
parts is ensured, and on the other hand, any desired number of frame parts 
may be joined together without difficulty. 
The connection according to the invention is assembled in an extremely 
simple manner. It comprises a specially shaped dowel which extends 
outwardly from one frame part and which is inserted into a specially 
shaped opening in the the second frame part, whereafter the dowel can be 
wedged into firm engagement with interior surfaces of the opening by 
tightening securing screws at the side. Such a connection allows not only 
a quick and reliable attachment, but also provides easy releasability. 
When the dowel extends only throughout a part of the depth of the said 
opening, sufficient space remains for adjoining a further horizontal first 
frame part to the second frame part. In this case, two securing screws are 
provided in the second frame part, parallel to each other, which are then 
tightened. 
An especially firm connection results from the fact that the dowel has two 
abutting surfaces inclined at an angle to its longitudinal central plane, 
and that two corresponding, inclined surfaces are also provided in the 
opening. Preferably, the angle of inclination of the abutting dowel 
surfaces is slightly larger than the angle of inclination of the 
corresponding surfaces in the opening. The angular difference is 
preferably less than 1.degree.. 
The converging inclination of the abutting surfaces in the opening and the 
corresponding surfaces results in the dowel being pressed extremely firmly 
against the inner surfaces of the female half of the connection when the 
securing screws are tightened. The high pressure exerted by the screws is 
distributed over large surface areas that abut one another so that the 
specific surface pressure in this connection remains low. 
It has proved particularly advantageous that the abutting dowel surfaces 
and the corresponding opening surfaces are inclined at an acute angle to 
the longitudinal central plane of the dowel or of the opening. The acute 
inclination of these surfaces results in a desired wedge effect which 
leads to the desired rigid locking of the dowel in the female half of the 
connection. 
Suitably, the form of the dowel and of the surfaces in the opening are such 
that when the dowel is secured, the surface opposite to the surface to 
which the screw is applied remains spaced from the wall it faces in the 
opening. The rigidity of the connection is thus determined exclusively by 
the tightness of the screws. 
In a further preferred embodiment of the invention, the dowel is angled. It 
is also possible to provide the dowel with a Y shape. 
The advantage of such angled or Y-shaped dowels is that frame parts can be 
joined together that are not at right-angles to each other. With a 
Y-shaped arrangement, three frame parts can be interconnected as might be 
required for example at the corner connection of a desk combination.

In the illustrated embodiment, the legs 1 of a furniture unit are connected 
to one another by horizontal struts 2 which have a profiled cross section 
as best seen in FIG. 2. Two legs 1 are each connected to one another via a 
short strut 3. 
At the corners formed by the legs 1 and the short struts 3, female halves 4 
of the connection with openings 8 (FIG. 2) are provided. 
At the ends of the profile struts 2 are dowels 5 which protrude beyond the 
ends of the struts 2. The dowels are secured, for example by being press 
fit into chambers 19 in the profile. 
The dowel 5 has abutting exterior surfaces 11 and 12 which bear against 
corresponding interior surfaces 9 and 10 of opening 8 when the dowel 5 is 
fitted in the opening 8 of the female half 4 of the connection. A securing 
screw 6 or 7 is in thread engagement with female half 4 of the connection, 
extends into opening 8 (see FIG. 3), and when tightened presses the dowel 
surfaces 11 and 12 against the corresponding opening surfaces 9 and 10 in 
the female half 4. The leading surface 17 of the dowel remains distant 
from the opposing surface 18 located between the contact opening surfaces 
9 and 10 even when the connection is tightened. Behind the abutting 
surfaces 11 and 12 are oppositely inclined surfaces 15 and 16 on the dowel 
5, and oppositely inclined surfaces 13 and 14 in the opening 8. 
When the securing screws 6 and 7 are tightened, the center of the dowel 5 
is offset by the distance a in relation to the vertical plane 20 through 
the upper and lower corners of the opening 8. 
The abutting dowel surfaces 11 and 12, and the corresponding surfaces 9 and 
10 in opening 8 are arranged at an acute angle to the horizontal plane 
IV--IV. These surfaces converge towards the horizontal plane at the side 
opposite to the securing screws 6 and 7. 
In FIG. 4 can be seen how two first frame parts are arranged in 
continuation, and are connected to an intervening second frame part. The 
protruding dowels 5 from the first frame parts are inserted, one from each 
side, into the opening 8 and the securing screws 6, 7 are tightened. 
Release of the connection presents no problem. 
In the embodiment according to FIG. 5, several horizontal frame parts are 
interconnected to form the corner of a furniture unit. Arranged at 
right-angles to each other, the parts 2' and 2a" are joined by means of a 
plate 23. Beneath the plate is a supporting leg 22 which must necessarily 
be provided on all such corner connections. 
The frame part 2' has an angled dowel 5' at each end. The frame part 2a' 
has a Y-shaped dowel 5" at its end. The free ends of the dowels 5' extend 
into openings in the frame parts 1'. The free arms of the Y-shaped dowel 
5" also extend into other openings of the abutting frame parts 1'. 
Securing of the free ends of the dowels within the openings takes place in 
the manner described and illustrated in connection with FIGS. 1 to 4. 
The connecting plate 23 can be so constructed that the distance between the 
rear end of frame part 2a' and frame part 2' is adjustable. The 
construction shown in FIG. 5 can be assembled completely free of stress, 
and necessary adjustments when erected are easily possible.