PROCESS FOR MANUFACTURING LADDER TAPES PARTICULARLY FOR VENETIAN BLINDS

Abstract: The process for manufacturing ladder tapes which is particularly usable for venetian blinds consists of mutually connecting a first tape and at least one second tape (1,2) by means of at least one thread (3) of the first tape; the first and second tapes are furthermore arranged substantially parallel to one another on the same head of a manufacturing loom.

Description: PROCESS FOR MANUFACTURING LADDER TAPES PARTICULARLY FOR VENETIAN BLINDS DESCRIPTION The present invention relates to a process for manufacturing ladder tapes particularly for Venetian blinds. As is Known, ladder braids or ladder tapes are currently used for the manufacture of so-call d Venetian blinds, and allow, in addition to the support of the various slats of the Venetian blind, the packing of the various slats or their extension together with the rotation thereof, during the lifting or lowering of said blind, in order to vary the amount of light inside a room. Between the ladder braid and the ladder tape, undoubtedly the latter is preferred by both manufacturers and users of Venetian blinds, since, by being wider than the braid. _it allows to completely cover the slot of each slat inside which the slat's actuation cord passes. Ladder tapes are currently manufactured on shuttle looms or on needle looms, arranging one tape above the other and then drawing from one of the tapes , for example the upper tape, one or more series of warp threads so as to form a portion of a third tape which is parallel to the upper tape and to the lower one and is comprised therebetween. After weaving a certain length of said third tape, the warp threads which define it are carried to the lower tape, wea v in * th m th wi for ce ain extent and then carrying them back to the upper tape, with a direction which is perpendicular to both the upper tape and the lower tape; then the normal weaving of both the upper tape and the lower tape continues for a certain BSTITUTE SHEET extent, and the above described cycle is then resumed. The differences of ladder tapes manufactured on shuttle looms with respect to ladder tapes manufactured on needle looms consist exclusively in the fact that in shuttle looms the manufacturing speed is lower than that of needle looms but, on the other hand, there is the advantage of being able to weave the portion of the third tape, whereas in needle looms the threads which define said third tape portion are not woven together and therefore remain loose. In any case, both ladder tape forming processes, both on shuttle looms and on needle looms, entail the fact that, once the forming of the ladder tape is complete, the warp threads which vertically connect the upper tape to the lower one must, be cut manually so as to be able to space the two tapes (the upper one and the lower one) apart and thus obtain the completed ladder tape suitable for receiving the slats of the Venetian blind. This last manual operation is the one which unmistakably determines the high cost of known ladder tapes, since the labor required to manually cut said vertical threads is several times higher in cost with respect to the weaving material and to the weaving costs. It. furthermore often occurs that the worker- assigned to the cutting of said threads for vertical connection between the π in p fang and the lower aO , due to the difficulty in performing the cutting operation in view of the scarce workspace available, damages the tape, thus causing the rejection of all of the manufactured ladder tape. STITUTE SHEET In this situation, the technical aim of the present ' invention is to solve the above described disadvantages of the known art. Within the scope of this technical aim, an important object of the present invention is to provide a process for manufacturing ladder tapes particularly for Venetian blinds which allows to form, on a weaving loom, whether of the shuttle type, of the needle type or of any other type, a completely finished tape, thus eliminating the most labor-intensive operation, i.e. the manual cutting of the threads as described in the known art. Another important object of the present invention is to provide a process for manufacturing ladder tapes particularly for Venetian blinds which allows the ladder- tape thus obtained to have a very modest manufacturing cost which is considerably lower than that of ladder tapes currently manufactured conventionally. Not least object of the present invention is to provide a process for manufacturing ladder tapes particularly for Venetian blinds which allows to substantially eliminate rejects due to errors in cutting the threads connecting the upper tape and the lower tape. This aim, these objects and others are achieved by a process for manufacturing ladder tapes particularly for Venetian blinds, characterized in that it consists of mutually connecting a first tape and at. least one second tape by means of at least one thread of said first, tape, said first, and second tapes being arranged substantially parallel to one another on the same head of a weavinα loom. Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment of the process for the manufacture of ladder tapes particularly for Venetian blinds, illustrated only by way of non- limitative example in the accompanying drawings, wherein: Figure 1 is a schematic plan view of a first tape and of a second tape which are ladder-woven for example on a needle loom following the process according to the invention; Figure 2 is a perspective view of the ladder tape obtained with the process illustrated in Figure 1 according to the invention; and Figure 3 is a schematic plan view of a first tape and of a second tape which are woven on a shuttle loom following the process according to the invention. With reference to the above figures, the process according to the invention consists of mutually connecting a first tape and at least one second tape by means of at least one thread of the first tape. The first tape and the second tape are woven on the same bead of a weaving loom of any type, whether of the shuttle type, of the needle type or of another type, and are arranged substantially parallel to one another. More in particular, with reference to Figure 1, for the sake of easy understanding, the numerals 1 and 2 generally and respectively indicate thf*. f <4t tape and the second tape which are being woven on the same head for example of a needle loom. The numeral 3 indicates a thread which, in the case of weaving performed on a needle loom, is a warp thread SUBSTITUTE SHEET of the first tape 1 which is defined by a thin cord or tape which has a larger diameter than the remaining warp threads present on the first tape 1 and is suitable for bearing the weight of a slat of the Venetian blind. Initially, the warp thread 3 of the first tape 1 is woven like the other warp threads in the tape 1 and, in a first transfer, is orientated with a direction which is substantially vertical with respect to the longitudinal extension of the first tape 1 and of the second tape 2 and is woven in, i.e. tied to the first tape 1, for a first portion thereof, indicated by 4, which is equivalent to a preset distance from the first edge, indicated by 20, of the first tape, and is then carried loose, by means of transfer means which are known and not illustrated, such as for example an open sickle, below the second tape 2 by an extent which is generally indicated by 5, and is then tied to the second tape 2 for a second portion thereof indicated by 6 which is equivalent to a preset distance from the second edge 7 of the second tape 2. The warp thread 3, after being connected, by means of the aid for example of a tab needle 21, to the second edge 7 of the second tape, is carried, with a second transfer, back above the first tape 1, keeping it respectively loose and tied, as illustrated in Figure 1, with respect to the second tape 2 and to the first tape 1, as performed in the first transfer. As is clearl v shown ?n Figure 1, after the firs transfer, the warp thread has a first tied portion 4 which is equal to the amount of loose thread 5 below the second tape 2. The loose thread 5 thus corresponds to the width L TITUTE SHEET of the second tape, which is equal to the width L of the first tape, minus the second tied portion 6, and therefore the total amount of loose thread above or below the two tapes 1 and 2 is equivalent to the width L of each of said tapes. By conveniently spacing the two tapes 1 and 2 apart, and more precisely by varying the length Y of the loose thread portion 3 comprised between the two tapes 1 and 2, the preset distance is obtained according to the preselected width of the slats of the Venetian blind. By means of the second transfer, the warp thread 3, as shown, is returned onto the first edge 20 of the first tape and is thus warped in a third portion thereof, generally indicated by 8, on said first tape. The warp thread is subsequently carried, with a third transfer, as will be described in greater detail hereinafter, below the second tape 2 and then, with a fourth transfer, back above the first tape 1. More in particular, during this third transfer, the warp thread is again orientated along a direction which is vertical with respect, to the longitudinal extension of both the first tape 1 and the second tape 2, and has a fourth tied portion 9, equal in width to the second tied portion 6 produced during the first transfer, and is then subsequently left loose and carried below the second tape 2, to which it is tied again in a fifth tied portion, generally indicated by 10, on said second tape 2. The tied portion 10 has a width equal to the first. tied portion 4 produced during the first transfer of the warp thread 3. As clearly visible again in Figure 1, during the SUBSTITUTE SHEET fourth transfer from below the second tape 2 above the first tape 1, the warp thread 3 is respectively tied and left loose with respect to the second tape 2 and from the first tape 1, exactly as in the third transfer. Thus, in the third transfer, the fourth tied portion 9 is equal to the width of the loose thread below the second tape 2, indicated by 11. Said loose thread 11 is equal to the width L of the second tape 2 minus the fifth tied portion 10 of the warp thread on said second tape 2. Essentially, it can be seen (Figure 1) that during the process the first tied portion 4 of the warp thread 3 of the first tape 1 is equal to the tied portion 10 of the warp thread 3 on the second tape 2, whereas the second tied portion 6 of the warp thread 3 on the second tape 2 is exactly equal to the fourth tied portion 9 of the warp thread 3 on the first tape 1. The equivalence of the first tied portions as described above leads to a corresponding equivalence of the loose portions of the warp thread 3. It should furthermore be specified that the width of the third portion 8 of the warp thread 3 is proportional to the radius of curvature of a slat of the Venetian blind, as can be seen for example from Figure 2. The portion 25 , added to the portion 8 , ins tead corresponds substanti ally to the distance between two consecutive sl ats of the Venetian blind . Finally , i t shoul d be speci f i ed th a t, a f ter th e portion 25 the width of the tied portions and of the loose portions , respectively of the first, tape and of the second tape , are reversed , so a s to provide a balanced support of each of the slats of the Venetian blind. By way of example, Figure 3 illustrates a ladder tape manufactured with the process according to the invention and woven on a shuttle loom. Figure 3 shows that the thread or thin cord 3, which is not a warp thread in this case, is woven into the edge of the first tape and, in a first transfer, is tied to the first tape 1 in a first portion, indicated by 4, which is equivalent to a preset distance from the edge 20, and is then carried loose, by means of a shuttle, below the second tape 2 and is tied thereto in a second portion 6 thereof which is equivalent to a preset distance from the second edge 7 of the second tape 2. The thread 3, after being woven in on the second edge 7 of the second tape for an extent which is proportional to the radius of curvature of a slat, is subsequently tied, during a second transfer, to the second tape 2 for an extent which is equal to the first portion 4 and is then left loose to be carried above the first tape 1 and again tied thereto for an extent which is equal to the second portion 6 at a preset distance from the first edge 20 of the first tape 1. The thread 3, as shown in Figure 3, is subsequently woven into the edge 20 of the first tape 1 in a third portion 8 thereof, in the case of weaving on a shuttle loom which is eouivalent o an amount which corresponds substantially to the distance between the lower part, of a slat and the upper part of the subsequent slat of two consecutive slats of the Venetian blind. In a third transfer, the thread 3 is again tied to SUBSTITUTE SHEET the first and second tapes 1 and 2 respectively for a fourth portion 9 thereof (first tape) and for a fifth portion 10 thereof (second tape) . The fourth portion 9 is equal to the second portion 6 and the fifth portion 10 is equal to the first portion 4 produced during the first transfer, and so forth. Figure 2 illustrates a portion of the ladder tape which is also the subject of the present invention and is obtained with the above process; said figure allows to understand that, for example by taking the second tape 2 and moving it above the first tape 1, said first and second tapes are connected by a plurality of connecting elements, respectively indicated by 12 and 13, each of which is defined by two warp threads 3. The retention elements 12 and 13 are respectively spaced apart by the preset amount and are furthermore mutually offset by an amount which is equivalent to the radius of curvature of the slats 23, each of which is inserted between a pair of retention elements so that it can be effectively retained and supported during the operation of the Venetian blind. In the case of a tape produced on a shuttle loom, the slats are inserted in the space defined by the first and second transfers of the thread 3. The invention achieves the proposed aim and objects and achieves numerous and important advantages. A new process for the manufacture of ladder tapes rticul ly for Venetian blinds has in fact been devised and allows to produce a ladder tape which has an extremely modest cost, considerably lower than that of known ladder tapes, since the labor-intensive cutting operation present on known ladder tapes is eliminated. ET More specifically, the process according to the invention obtains a so-called "double" ladder tape which is formed and completed directly on a weaving loom and requires no further treatment. The invention thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the present inventive concept. All the details may furthermore be replaced with technically equivalent elements. The materials employed, the shapes and the dimensions may be any according to the requirements. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs. SUBSTITUTE SHEET

Claims: CLAIMS 1. Process for manufacturing ladder tapes particularly for Venetian blinds, characterized in that it consists of connecting a first tape and at least one second tape (1, 2) by means of at least one thread (3) of said first tape, said first and second tapes being arranged substantially parallel to one another on the same head of a weaving loom. 2. Process according to claim 1, characterized in that said thread (3) of said first tape (1) , in a first transfer, is tied thereto for a first portion (4) thereof which is equivalent to a preset distance from the first edge (20) of said first tape and is carried loose, by means of transfer means, below said second tape (2) and is again tied thereto for a second portion (6) thereof which is equivalent to a preset distance from the second edge (7) of said second tape, said thread, after its connection on a second edge (7) of said second tape, being subsequently returned from said second tape above said first tape with a second transfer, said thread, during said second transfer, being respectively tied and left loose again with respect to said second tape and to said first tape, said thread being subsequently connected, for a third portion (8) thereof, on said first edge of said first tape and being carried, with a third transfer, again below said second tape and then, with a fourth transfer, back above said first tape. 3. Process according to claim 2, characterized in that, for each of said transfers, said tied portions of said thread on said first tape are equal to the loose portions of said thread on said second tape, each of SUBSTITUTE SHEET said loose portions corresponding to the width of one of said tapes minus the corresponding tied portion. 4. Process according to claim 2, characterized in that the sum of the width (L) of each of said first and second tapes plus the distance (Y) of said first tape from said second tape is substantially equal to the width of a slat of said Venetian blind. 5. Process according to claim 2, characterized in that the sum of the loose portions of said thread during said first and second transfers is equal to the sum of the loose portions of said thread during said third and fourth transfers. 6. Process according to claims 1 and 2, characterized in that said first tape is carried above said second tape or vice versa and in that said slat is inserted respectively between said threads connected to said first and second tapes. 7. Process according to claim 2, characterized in that said thread has, in said third transfer, respectively a fourth portion and a fifth portion (9,10) which are tied respectively on said first tape and on said second tape and are respectively equal in width with respect to said second tied portion and to said first tied portion of said first transfer. 8. Process according to claim 2, characterized in that, during said fourth transfer said thread is respectively tied and left loose with respect to said second tape and said first tape as in said third transfer. 9. Process according to claim 2, characterized in that said third portion of said thread is proportional to the radius of curvature of a slat (23) of said SUBSTITUTE SHEET Venetian blind. 10. Process according to claim 2, characterized in that said third portion of said thread is substantially equal to the distance between the lower part of a slat and the upper part of the following slat of said Venetian blind. 11. Process according to claim 2, characterized in that said transfer means comprise at least one open sickle. 12. Process according to claim 2, characterized in that said transfer means comprise at least one shuttle. 13. Ladder tape particularly for Venetian blinds, characterized in that it comprises a first tape (1) and a second tape (2) which are mutually connected by means of at least one thread (3) of at least said first or second tapes, said thread being alternately tied and left loose thereon with a process according to one or more of claims 1 to 11. "

Inventors: BRACCIO MARIO, BRACCIO, MARIO
Applicants: BRACCIO MARIO, BRACCIO, MARIO
Application year: 1991
Main classification: E06B9
IPC codes: D03D1, E06B9