The present invention relates to a machine for the production of Venetian blinds, said machine having a supply device for intermittently supplying from a supply reel a metal strip in the longitudinal direction of said strip through a number of ladder-tapes, and hav¬ ing a punching station with means for punching lift cord holes in the free end portion of the metal strip before this end portion is inserted in the ladder-tapes, and having a separating station for separating from the free end portion of the metal strip the individual Vene¬ tian blind slats inserted in the ladder-tapes.

A machine of this type is disclosed in Swedish pa¬ tent specification No. 323,787 and has proved to be a highly efficient machine providing for extensive ra- tionalisation of the production of Venetian blinds.

There is, however, a demand for still higher production rates, thereby to achieve an even higher rationalisation of the production of Venetian blinds, and it was found that the machine disclosed in above-mentioned patent, and other similar prior art machines, on entirely mecha¬ nical grounds could not be redesigned for any essential¬ ly higher production rates than those presently employed. In view hereof, Venetian blind producers have need of an improved machine with which higher production rates can be achieved.

It therefore is an object of the present inven¬ tion to provide a machine by which the production rate can be increased far beyond that of prior art Venetian blind production machines. Another object of the invention is to provide a Venetian blind pro¬ duction machine in which Venetian blinds of different lengths can be produced in one and the same production run. Further objects of the invention will appear from the following description.

These and other objects of the invention are achieved if the Venetian blind production machine referred to above is provided with a punching sta¬ tion which comprises several groups of punching tools for punching lift cord holes for several successive Venetian blind slats in the free end portion of the metal strip, and if the punching station is formed with at least a corresponding number of separating punches for simultaneously separating Venetian blind slats for a corresponding number of simultaneously produced Venetian blinds. The characteristic features of the invention will appear from claim 1.

The Venetian blind production machine according to the invention comprises a punching station with at least two groups of punching tools for punching lift cord holes in at least two successive Venetian blind slats in the free end portion of a metal strip inserted in the machine. The punching station is fol¬ lowed by a combined mounting and separating station, said separating station comprising at least a cor¬ responding number of separating punches for simulta¬ neously separating the Venetian blind slats for the same number of simultaneously produced Venetian blinds, The invention is based on the idea that the advance of the metal strip along the machine bed is to occur for continuous and maximum periods of time with a minimum of acceleration and retardation cycles during the Venetian blind production.

The invention thus is based on a new approach to the Venetian blind production machine technique, in that several Venetian blinds are manufactured in one and the same machine and in one and the same slat punching and slat separating run, the slats being separated simultaneously from one another and from the remaining portion of the metal strip by punching. This production technique thus makes it possible to increase the production rate of the machine to a con-

siderable extent, and this increase is due not only to the fact that several Venetian blinds are manufac¬ tured at the same time, but also to the fact that the loss of time resulting from the acceleration and retardation of the metal strip passing through the machine is decreased. Thus, if one were to produce in a machine a Venetian blind having a length of 800 mm, and comprising 82 slats, this can be effected in prior art machines in about 80 seconds, whereas, if a machine according to the present invention is used, it is possible to produce in one and the same machine several Venetian blinds in succession, and for each additional Venetian blind one merely need add, under otherwise identical conditions in the production machine, about 18 seconds of machine time. If five Venetian blinds having a length of 800 mm and each comprising 82 slats are manufactured simultaneously in a machine according to the present invention, the total production time for these five Venetian blinds would be about 170 se- conds. The machine time for each Venetian blind would then be about 34 seconds, and this should be compared with the machine time of about 80 seconds for producing a single Venetian blind in the same machine.

Besides, the production capacity can be further increased by connecting two or more feed paths in parallel, in which case the machine has at least some punching tools which are common to or operated jointly for two or more of said feed paths.

The invention will be described in more detail below, reference being had to the accompanying drawings which illustrate different parts of an embodiment of a Venetian blind production machine according to the present invention. In the drawings:

Fig. 1 is a lateral view of parts of a Venetian blind production machine according to the invention; Fig. 2 illustrates, on a larger scale, a detail of the machine bed at the junction between two Vene¬ tian blind mounting stations;

Fig. 3 illustrates an alternative embodiment of a magazine in a Venetian blind production machine; Fig. 4 is a lateral view of the said magazine; Fig. 5 is a lateral view of a lifting section in the Venetian blind production machine;

Fig. 6 is a lateral view of a punching unit for in¬ sertion at the junction between two adjacent Venetian blind production stations;

Fig. 7 is a section on line VII-VII in Fig. 6; Fig. 8 is a schematic sectional view on line VIII-VII in Fig. 2; and

Fig. 9 corresponds to Fig. 8 but illustrates a modified machine comprising two slat advancing paths with common punching- tools. The embodiment illustrated in the drawings of a Venetian blind production machine according to the present invention comprises a frame 1 having an elongate machine bed 2 along which a number of punches, magazines and lifting units can be clamped in desired positions paying regard to the Venetian blind production concerned. The different units are interconnected by a main shaft 3 which is driven by a motor 4. At the infeed end of the machine, a supply reel 5 is provided for supply¬ ing a metal strip 6 which passes over a guide pulley 7 and can be fed, by means of drive rollers 8, in the longitudinal direction of the machine in a manner explained in detail below. The drive rollers 8 are driven by a motor (not shown). As will appear from Fig. 8 which merely shows the right-hand end of the machine in Fig. 1, several different Venetian blinds can be produced in succession in different mounting stations 10, 11, 12 separated from one another by means of punching stations equipped with punches 13 which are shown in section in Fig. 8. The left-hand punch 13 in Fig. 8 may be a separating punch separating the different slats from the free end portion of the metal strip. In that case, the machine has a length

which makes it possible to produce three Venetian blinds at the same time.

Fig. 1 shows but a few punches 14 serving to punch the lift cord holes 15 of the Venetian blind slats. This Figure also shows a punch 16 mounted at the junction between the machine punching section for punching lift cord holes (the left-hand part of Fig. 1) and the machine section for mounting Venetian blinds (to the right of the punch 16). Furthermore, a separating punch 17 is shown which forms the junction between two Venetian blind mounting stations, for example the stations 10 and 11. At the left-hand end of Fig. 1, the machine has a clamping device 18 for clamping the metal strip 6 during the joint punching runs in the machine. Thus, the machine first advances the strip 6 through all of the stations up to an end stop 19 (Fig. 8) mounted for pivotment about an axis 20 between two abutments 21. The movement of the end stop 19 is sensed by a microswitch 22 which, upon sens- ing of the metal strip end, activates the clamping de¬ vice 18 and clamps the metal strip. Before that, the metal strip has been advanced such that it positively forms a loop 23. While the clamping device 18 is acti¬ vated, punching is effected by means of all punches 14, 16, 17 so that the portion of the metal strip 6 between the clamping device 18 and the punch 16 is provided with lift cord holes, simultaneously as the Venetian blind slats are separated by the punches 16, 17.

The different mounting stations also are provided with lifting and magazine units 24 of a design spe¬ cified in the following.

Fig. 2 illustrates on a larger scale the junc¬ tion between two mounting sections, for example the sections 10 and 11, in the Venetian blind production unit. Fig. 2 shows the position of the machine after punching arid after lifting of the mounted slats. Thus, the punch 17 with the punching unit 13 proper has

just separated the slats from one another in that the punching unit 13 has penetrated down into its die 25. The separated slats 26 have been lifted against the underside of the upper rail 27 of the Venetian blind by means of the lifting units 28 which is shown in more detail in Fig. 5. The ladder-tape supply device 29 is designed in known manner and sees to it that the rungs of the ladder-tapes are placed alternately on one and the other side of the lift cord holes of the different Venetian blind slats 26.

Figs. 6 and 7 illustrate a separating punch 17 in more detail. The punching unit 17 thus has a punch 13 cooperating with the die 25. The design of the die 25 and the punch 13 will appear from the sectional view shown in Fig. 8 and directly produces finished ends of the different Venetian blind slats 26. The punch die 25 is stationary relative to the machine bed 2 and is fixedly mounted in a holder 31 which is connected with plates 32 in which four guide wheels 33 are mounted. The guide wheels control the recipro- catory movement of a slide 34 connected with an arm 35 on which the punch 13 is mounted. The slide 34 is connected with the main shaft 3 via an eccentric 36. Upon rotation of the main shaft, the slide 34 and thus the punch 13 will move up and down.

Fig. 5 illustrates an example of the design of a lifting unit 28. The lifting unit has a lifting arm 34 which is mounted on a plate 39 movable up and down by means of an eccentric between two frame plates 41 that can be affixed to the machine bed 2. The ec¬ centric 40 is connected with the main shaft 3 of the machine. The lifting movements of the lifting arm 38 are synchronised with the movements of the punches 13, such that the correct operational sequence is obtained.

Figs. 3 and 4 illustrate an example of the design of the different magazines in the machine. The magazine

29 has clamping means 42 for aligning the ladder-tapes

30 and keeping them taut during mounting. The upper part 43 of the magazine is provided with flaps 44 pivoting on journals 45. When the Venetian blind slats 26 are lifted, they are urged past the pivotal flaps 44 which then hold the lowermost slat 26 and all over¬ lying slats and also the rail 27, while the lifting arm 38 returns to its position below the level of the path in which the metal strip 6 is advanced. In the embodiment illustrated in Figs. 3 and 4, a resilient tape 46 is used which holds the finished parts of the Venetian blind down against the flaps 44 and which for. this purpose travels over a guide pulley 47.

In the embodiment shown in Fig. 2, use is made instead of a spring-biased arm 48 which, by means of a spring 49, is urged against the upper side of the mounting rail 27 of the Venetian blind.

As will appear from the above, the Venetian blind production machine according to the present invention makes it possible to increase considerably the produc¬ tion rate, i.e. to decrease the machine time for each Venetian blind. This is made possible on the one hand in that the several Venetian blinds are manufactured during each punching and lifting operation and, on the other hand, in that the acceleration and retardation times during production are reduced considerably. In the above-mentioned embodiment, it is possible to have a machine cycle during which acceleration from standstill to high speed is, for example, 50 mm, whereupon braking is initiated at, for example, 250 mm before the end stop 19. The actual cutting/ punching, the lifting and the folding of the ladder- tapes can be carried out in but 0.6 second. For example, if five Venetian blinds are manufactured in succession, the total length of these blinds being 4 m, it is possible, at an advancing speed of 0.21 second/800 mm during the high-speed advancing, to produce these

five Venetian blinds with 82 slats each during a mount¬ ing time of about 170 seconds.

The invention may, of course, be modified in many different ways without departing from the basic idea, i.e. maximum utilisation of the machine with a minimum of acceleration and retardation periods, all lift cord holes being punched in the free end portion of the metal strip while simultaneously separating the finished Venetian blind slats from a strip portion in which lift cord holes have previously been punched. A further modification of the invention is shown in Fig. 9. In this Venetian blind production machine, two slat advancing paths have been connected in parallel, such that two metal strips 6, 6' are punched and worked in the same manner as the metal strip 6 in the embodiment according to Figs. 1-8. For the sake of simplicity, like reference numerals, although primed, have been used for like components. The essential difference between the embodiment according to Figs. 1-8 and the embodiment according to Fig. 9 is that the punches 13, 13' are joined together in pairs by means of con¬ necting members 13" and thus are operated jointly by means of a common punch driving motor. To ensure that the two metal strips 6, 6' have reached the cor- rect punching position before punching is initiated, the two microswitches 22, 22' may be interconnected such that both must have been activated by the metal strips before punching can begin. By doubling the machine in this manner, the capacity is doubled. It will be appreciated that this basic idea can, of course, be increased to three or four parallel slat advancing paths and the associated punching and other equipment. If it is desired to produce Venetian blinds of dif¬ ferent lengths in two adjacent advancing paths, se- parate punches may be introduced into either one of these paths such that but a few or perhaps none of the punches are common to the slat advancing paths.