Method for assembling slats of venetian blinds and mechanism for use in the exercise of the method

In the production of slat packages for Venetian blinds, the slats are placed over each other and introduced between a first and a second transverse band in double rungs in carrying bands or ladders including bands or cords. The slats are conveyed one by one to the carrying band and lifted after being introduced into a double rung to enable mechanical introduction of the slats between the double rungs. A double rung is stretched between two teeth projecting over the plane in which the slats are conveyed. A slat is conveyed forward until it has passed under the first of the two transverse bands, and the slat is then lifted so that when further conveyed it passes over the second of the two transverse bands. The slat can be lifted by an inclined plane placed between the teeth.

FIELD OF THE INVENTION 
The present invention concerns a procedure for production of slat packages 
for Venetian blinds whose slats, placed over each other, are introduced 
between a first and a second transverse band in double rungs in carrying 
bands or ladders consisting of bands or cords, by which procedure the 
slats are conveyed one by one to the carrying band and lifted after being 
introduced into a double rung of the carrying band or ladder. 
1. Background of the Invention 
It is possible in order to ensure that the slats of a Venetian blind cannot 
turn round in the carrying bands to use carrying bands with two transverse 
bands in each rung, between which the slats are introduced. In principle, 
the introduction can take place in two ways, either by each slat being 
introduced directly between the two bands in each rung or by each slat 
being introduced after the two bands have been crossed in such a way that 
the lower band lies over the slat and the upper band lies under the slat. 
2. Description of the Prior Art 
From DE patent paper 2,003,304 a procedure is known where a carrying band 
with double ladder rungs is stretched between two rotary discs having 
recesses placed in the periphery. The distance between two successive 
pairs of recesses corresponds to the distance between two successive 
double rungs of the carrying ladder. Before a slat is introduced between 
the two bands of a rung, the bands are separated by means of special 
spreading devices, which are then placed in the conveying path of the 
slat. After the slat has been introduced, the spreading devices must be 
moved away from this conveying path. The known procedure thus requires a 
comparatively complicated equipment. Besides, it is not possible by the 
known procedure to introduce a slat into a rung whose transverse bands are 
twisted. 
SUMMARY OF THE INVENTION 
The purpose of the invention is to present a procedure which makes 
introduction of the slats by means of a simple and safe equipment 
possible. Furthermore, it must be possible to introduce the slats between 
twisted transverse bands. 
This is achieved according to the invention in such a way that a double 
rung of ladder is stretched between two teeth projecting over the plane in 
which the slats are conveyed, that a slat is conveyed until it has passed 
under the first of the two transverse bands, and that the slat is then 
lifted so that when further conveyed it passes over the second of the two 
transverse bands. 
The presented procedure can immediately be mechanized by means of an 
appropriate mechanism which moves and stretches the carrying band. 
It is desirable that the slat, after being conveyed until it has passed 
under the first of the two transverse bands, is lifted by means of an 
inclined plane placed between the teeth. Hereby correct lifting of the 
slat is ensured in a very simple way. 
It should be noted that the double rung can be stretched between the two 
teeth with the end of the carrying band that is uppermost in the finished 
slat package turning either towards or away from the conveyed slat. In the 
first case the slat will be introduced immediately between the two 
transverse bands. In the second case the slat will be introduced between 
twisted transverse bands. 
As previously mentioned, the invention also concerns a mechanism for use in 
the exercise of the procedure and comprising protruding teeth between 
which a double rung of ladder can be stretched. According to the invention 
this mechanism comprises a rotary roller with pairs of teeth placed on the 
periphery, and where the distance between two successive pairs of teeth 
corresponds to the distance between two successive double rungs of a 
carrying ladder. The roller is turned a tooth every time an introduced 
slat is lifted free of the mechanism, so that the succeeding double rung 
is in the right place for the introduction of the succeeding slat.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1 and 2 show in schematic form carrying bands with double rungs of 
ladder 2,2' and the Venetian blind slat 3, which has been introduced into 
a rung directly between its two transverse bands and between twisted 
transverse bands, respectively. The double rungs ensure that the slats 
cannot turn round in the carrying band. 
It appears from FIGS. 3-5 how slats 3 can be introduced mechanically one by 
one between the two transverse bands in a rung. A double rung 2,2' is 
stretched in such a way that the two transverse bands 2 and 2' are 
separated between two teeth 4 projecting over the plane in which the slat 
is being conveyed, see also FIGS 6-9. The slat 3 is moved forward until it 
has passed under the first of the two transverse bands 2 (FIG. 4). After 
that the slat is lifted, in the embodiment shown here by means of one or 
more inclined planes 5 placed between the teeth, so that when moved 
further forward the slat passes over the second of the two transverse 
bands 2'. After that the slats are lifted in an actually known way (FIG. 
8) so that a succeeding slat can be introduced. Until that is done, the 
succeeding double rung is stretched between either the two above-mentioned 
teeth or between the succeeding teeth in a mechanism as shown in FIGS. 
6-9. 
The shown mechanism comprises a rotary roller with pairs of teeth placed on 
the periphery. The distance between two succeeding pairs of teeth 
corresponds to the distance between two succeeding double rungs. The 
roller is moved synchronously with the forward movement of the slats, so 
that the next rung of the ladder is in the right place when the next slat 
is moved forward. 
If the roller is turned as indicated by the arrow in FIG. 6, (in a 
clockwise direction) the introduction of the slats shown in FIG. 2 is 
achieved by introducing slat 3 under trailing band 2' and then over 
leading band 2 to form the twisted bands of FIG. 2. If the roller is 
turned as indicated by the arrow in FIG. 9 (in a clockwise direction), the 
introduction of the slats shown in FIG. 1 by introducing slat 3 under 
trailing band 2 and then over trailing band 2' to form the non-twisted 
transverse bands of FIG. 1 is acheived.