EP0287802A2 - Device for feeding cable from a supply reel to a cable fabrication machine - Google Patents

Abstract

The device serves for feeding cable from a rotationally driveable supply reel (12) to a cable fabrication machine (14-18) which draws cable (10) intermittently. The device consists of a first buffer store (24) which is arranged behind the supply reel (12) in the conveying direction of the cable (10), a second buffer store (20) and an intermediate conveying means (40). The first buffer store (24) contains a relatively great length of cable in the form of tensioned windings having variable circumference, whereas the second buffer store (20) has the form of a loose, comparatively short cable loop (20), from which the cable fabrication machine (14-18) can withdraw cable very easily and rapidly. <IMAGE>

Description

The invention relates to a device for feeding cables from a rotatingly drivable supply roll to an intermittently pulling cable assembly machine.

When processing cables, as typically used in cable assembly machines in the manufacture of connection cables for e.g. B. lamps and electrical household appliances, of ignition cables and. Like. Is done, pieces of cable of a certain length are cut from a supply of cables in the first step. So far this has been done with a cable length of z. B. 1 m with a cycle time of about 4.5 seconds. Recently, however, this cycle time of cable assembly machines has been reduced to about 1.5 seconds. Using the same machines, connecting cables of different lengths are manufactured one after the other. B. only short cables of less than 1 m in length, then z. B. Vacuum cleaner cable with e.g. B. 6 m length, the latter now with a cycle time of about 2.7 seconds. However, while the conveyors of the cable assembly machines are able to accomplish the exemplary conveying performance within these extremely short cycle times and brake in between, to stop the exact length of a cable piece and to accelerate again, the supply of the cable makes it difficult because the heavy cable drums cannot be accelerated and stopped intermittently like the drives and conveying devices of the cable assembly machines, which have a low mass. If there is no sufficient loose cable length between the cable drum and the consumer, a malfunction occurs there because its weak cable conveyor is not able to pull the cable from the storage drum. Conversely, malfunctions can also be expected if the cable drum, which cannot be braked so quickly, supplies too much cable, because then the loose cable will jam, lie on top of one another in an orderly manner, making withdrawal to the consumer more difficult or even blocked by loop formation.

Since the forces to be applied and intercepted increase with the square of the mass acceleration, a reinforcement of the drive and the storage of the cable drum, which is adapted to the shortened cycle times, would be a very complex solution to the problem described, especially since the faster cable assembly machines suggest moving to even larger cable drums, and while of the operation whose changing diameter and reduced mass would have to be taken into account when controlling the rotary drive.

Buffer stores in the form of so-called dancer rolls are already known in the processing of threads, wires and tapes (cf. DE 30 13 203 A1), but these should also be used Sudden, violent pulling of cables under the conditions mentioned still accelerates the mass of the dancer rolls very much, with the result that the cable is also heavily stressed, different slippage occurs when measuring certain cable lengths and the conveyor elements attacking the cable quickly wear out.

The invention is therefore based on the object of creating a device of the type mentioned which, with relatively weak drives and simple means with only a small space requirement, ensures a trouble-free cable feed to the cable assembly machine.

The above object is achieved in that in the conveying direction of the cable behind the supply roll one after the other, the cable in the form of tensioned windings with variable circumference receiving the first buffer store, a controllable conveying device and a second buffer store loosely holding the cable.

It is essential for the function of the new device that buffer stores of different types and in the order given are combined with one another because, in cooperation, they mutually eliminate their specific disadvantages, because otherwise they would not have been possible for the application of interest here. Although, for practical reasons, buffer storage with a content of, for example, 6 m of loose cable could hardly be accommodated and operated in a functionally reliable manner, a buffer storage which loosely holds the cable, for example in the form of a loop, can be used in the invention, since this only has one even in the case of long cable sections to be produced needs to have relatively small memory content. A cable length is sufficient for this, despite the high take-off speed is only a fraction of the length of the cable sections to be produced. The compensation takes place by means of the first buffer memory, which would be unsuitable as the sole intermediate memory for the reasons mentioned above, but which in connection with the second buffer memory can now bring out its specific advantages. It is able to store a sufficient length of cable in a small space in order to alternately dispense and resume several meters of cable if the consumer unplugs and stops cables of 6 m length, for example, at intervals of the order of 1-2 seconds. Since the cable is kept taut in the first buffer store, it can be guided precisely despite the high take-off speed and is prevented from being entangled.

On the other hand, the mass contained in the first buffer store is minimal in comparison to the storage drum, so that a weak, quickly accelerated drive for the controllable conveying device arranged between the first buffer store and the consumer is sufficient to pull cables out of the first buffer store just as or at least almost as quickly and to be delivered to the second buffer store as it is withdrawn from there by the consumer. In addition, the low-mass controllable conveyor can be braked very quickly again when the consumer stops the cable pull abruptly, so that one can manage with a comparatively small loose cable length in the form of a single loosely hanging cable loop between the first buffer store and the consumer does not devour itself in front of the consumer at this point despite the whipping movement of the cable.

In a preferred practical embodiment of the invention the first buffer storage in the manner of a pulley system consisting of two groups of rotatably mounted rollers with variable spacing between the groups. An upper group of roles z. B. stationary on a stand, while a lower group of rollers hanging on the cable is loaded by a weight. The unit consisting of the last-mentioned group of rollers and the weight can be guided on a vertical guide of the stand.

The controllable conveying device can be set down from the first buffer store and can be arranged at an intermediate distance therefrom. However, a very simple, space-saving version is preferred, in which the controllable conveying device consists of one of the fixedly mounted rollers of the first buffer store and a cooperating, rotatable pressure element, for. B. a pressure roller or a pressed belt, at least one of these two parts pressed against each other can be driven.

With an upper and a lower group of z. B. coaxially mounted rollers, ie with six cable strands between the upper and lower roller group, the first buffer memory can store about 10 to 15 m of cable at a height of about 2 to 3 m, and this length can be controlled by the controllable conveyor if necessary can be quickly fed to the second buffer memory, which only needs to contain a cable length of about 1 to 2.5 m in the form of a loose, freely sagging cable loop. For such a short loop, lateral movement of the cable between vertical walls is sufficient despite violent movement. It is understood that the loose cable loop in the second buffer store can be shorter, the more precisely the controllable conveying device between the first and the second buffer store is coordinated with the conveying device of the consumer. Because of the practically unavoidable tolerances in the coordinated conveyor tion for the cable and because of the inevitable slippage of the frictionally driven cable due to the strong acceleration and braking processes, a loose cable loop, which contains a certain amount of cable, is definitely attached between the first buffer store and the consumer. It also ensures the greatest possible protection of the cable and the best possible dimension of the cut cable lengths, because breaks and stretching of the cable as a result of abrupt tensions when accelerating the cable conveyor devices can be avoided. A stronger drive of the cable conveyor device of the consumer could be able to pull the cable directly from the first buffer store, but this only with the simultaneous acceptance of significantly higher voltages in the cable with the above-mentioned disadvantageous consequences. The invention, on the other hand, offers the guarantee that the consumer conveyor, running at maximum acceleration and speed, can pull cables out of a loose loop in every phase. The controllable conveying device between this loop and the first buffer store, on the other hand, is also the time in which the cable conveyor device of the consumer is at a standstill for conveying cables from the first buffer store into the loop, so that, depending on the cable lengths required, the controllable conveyor device between the first Ideally, the buffer memory and the loop should run evenly, but in any case can be operated with gentler changes in speed, which do not lead to undesired voltage peaks at the output of the first buffer memory loading the cable.

The above-mentioned advantage of the buffer store proposed according to the invention can already be achieved if the controllable conveying device arranged behind it is controlled by means of a simple on / off control. You can see a finely adjustable speed control for the conveyor arranged behind the first buffer store, depending on the cable length to be manufactured and the available length of the cable loop in the second buffer store, the acceleration of the cable can be reduced to the minimum value to be calculated in each individual case and a completely uniform cable feed from the first Buffer memory in the cable loop of the second buffer memory are largely approximated.

Since the cable length is measured very precisely when the cable pieces are cut to length in the cable assembly machine, there is basically the possibility that the unwinding speed of the supply roll and / or the conveying speed of the conveying device behind the first buffer store is controlled as a function of the cable withdrawal speed of said or another consumer. Because of the inevitable slippage and the tolerance, however, monitoring devices must also be provided as a rule, which monitor the cable supply in the first and second buffer storage and, if necessary, provide corrections in the cable feed depending on the storage filling. In a simple embodiment of the device according to the invention, an optimal control of the drive speed of the storage drum and of the conveying device arranged behind the first buffer store can therefore be dispensed with, calculated from the characteristic of the cable requirement of the consumer. It is sufficient to have simple, separate control loops such that the unwinding speed of the supply roll as a function of the cable length contained in the first buffer store and the conveying speed of the conveying device arranged behind the first buffer store as a function of the cable length contained in the second buffer store are controlled so that the cable lengths in the first and second buffer memory between certain lower and upper limit values are kept. As monitoring devices such. B. Light barriers or electrical contacts are used, which register the position of the movable roller group of the first buffer memory and the length of the loosely hanging cable loop of the second buffer memory.

• Fig. 1 eine vereinfachte Seitenansicht einer Vorrichtung zum Zuführen von Kabel zu einem intermittierend Kabel abziehenden Verbraucher;
• Fig. 2 ein Kurvenschaubild zur Veranschaulichung der Fördergeschwindigkeiten der verschie­denen Kabel-Fördereinrichtungen der Vor­richtung nach Fig. 1;
• Fig. 3 eine Draufsicht auf die Vorrichtung nach Fig. 1.

The invention is explained below with reference to the drawing. Show it:

• Figure 1 is a simplified side view of an apparatus for feeding cables to an intermittent cable pulling consumer.
• FIG. 2 shows a graph to illustrate the conveying speeds of the various cable conveying devices of the device according to FIG. 1;
• 3 shows a top view of the device according to FIG. 1.

1 shows a cable 10, which is fed from a supply roll 12 to a consumer 14, of which only one cable feed device 16, which can be driven by a controllable drive motor A, and a cutting device 18 are shown for the sake of simplicity. The feed device 16 pushes a certain cable length through the cutting device 18 in each work cycle, where it is then cut off, in order to be subsequently processed further. The order of magnitude of the cycle times and the cable sections was mentioned at the beginning. In order to achieve these values with great accuracy and as little stress on the cable as possible, it is provided in front of the feed device 16 in the form of a loosely hanging loop 20 and, in the example, via a deflection roller 22 of the feed device 16 is supplied.

If possible, the cable loop 20 should not be chosen too large, because otherwise not only an inappropriately large amount of space is required, but also the tensile force to be overcome by the feed device 16 increases. In practice, a cable length in the loop 20 of approximately 1 to 2.5 m has proven to be expedient.

Arranged in the conveying direction of the cable 10 in front of the cable loop 20 is a buffer store, designated overall by 24, for a cable length of approximately 8 to 15 m. This buffer memory 24 consists of an upper roller group 26 mounted on a fixed common axis and a lower, coaxial roller group 28 hanging in the cable windings formed. In the example, both roller groups 26 and 28 each consist of 3 of the same size, independently rotatable on the axis of the Roller group of mounted rollers, which are designated 30, 32 and 34 in the case of the upper roller group 26 shown in plan view in FIG. 3. In addition to the upper roller group 26 there is another roller 36, which in the example is somewhat larger and is also mounted coaxially. The rollers 30-36 are mounted on a stand 38 fixed to the floor, which on the side of the rollers with a vertical guide, not shown, for. B. in the form of a dovetail groove, in which a carriage, also not shown, is displaceable in the vertical direction, which is firmly connected to the axis on which the three rollers of the roller group 28 are rotatably mounted. The mentioned carriage not only has a guiding function for the roller group 28, but also represents a weight load for the cable windings which are guided around the rollers of the roller groups 26 and 28.

As can best be seen from FIG. 3, the cable coming from the supply roll 12 is initially via the outermost upper roll 30 out, then runs down over the outermost lower roller of the roller group 28, up over the middle roller 32, down over the middle roller of the roller group 28, up over the roller 34, down again over the inner of the three rollers the roller group 28, back up over the larger roller 36 and from there to the cable loop 20.

In order to convey cables from the buffer store 24 into the cable loop 20, the larger roller 36 of the upper, fixedly mounted roller group 26 is designed as part of a controllable conveying device, designated overall by 40. It consists of the roll 36 z. B. from one or more pressure rollers 42 or preferably a belt guided over a plurality of deflection rollers, which rests on a larger circumferential area against the circumference of the roller 36 under pressure, the cable 10 between the roller 36 and the pressure roller or rollers 42 or said belt or another pressure element and is driven frictionally in the conveying direction towards the cable loop 20. The drive motor of the conveying device 40, designated B, can drive the roller 36, as shown in the example according to FIG. 1, but it can also, as indicated in FIG. 3, drive one of two pulleys, via which one is pressed against the roller 36 Driving belt runs.

The controllable conveyor 40 with its drive motor B simultaneously forms a backstop, which prevents cables from being pulled back from the loose cable loop 20 under the weight load by the roller group 28 and the guide carriage connected thereto into the buffer store 24. On the other hand, this weight load is not sufficient to pull cables from the supply roll 12 when the drive motor C is stopped. Accordingly, only to the extent that the drive motor C drives the supply roll 12, the cable length unwound as a result of the weight load caused by the lower one Coil group 28 and its guide carriage pulled into the buffer store 24, while the cable length conveyed from the buffer store 24 into the cable loop 20 is determined by the control of the drive B of the conveyor device 40.

The cable length currently contained in the cable loop 20 is registered in the example by a plurality of light barriers 44 arranged one above the other and additionally by a contact 46 actuated at a maximum cable loop. B. be provided that whenever the lowermost light barrier 44 no longer registers the cable loop 20, the drive motor B of the conveyor device 40 starts up and its conveying speed is accelerated, the shorter the cable loop 20 as a result of the cable being pulled off by the feed device 14 is what is indicated by the fact that the higher light barriers 44 no longer register the cable loop. The drive motor B of the conveyor device 40 thus runs at a different speed depending on which of the light barriers 44 arranged one above the other are currently responding, namely until the contact 46 is actuated when the maximum cable length in the loop 20 is reached and the drive B is thereby switched off.

In a manner corresponding to the light barriers 44, light barriers or contacts 48 are mounted one above the other on the stator 38 of the buffer memory 24, the bottom light barrier or the bottom contact 48 corresponding in function to the contact 46. When increasingly more cables are withdrawn from the buffer store 24 by the conveyor 40, which is registered by the light barriers or contacts 48, the drive motor C of the supply roll 12 switches to an increasingly higher speed. Only when the lower roller group 28 or the guide carriage connected to it again reaches the lowest light barrier or the lowest contact 48, is the drive motor C switched off.

2, the running or conveying speeds of drives A, B and C are shown one above the other on the time axis. In the example, the feed device 16 works with a cycle time of 1.5 seconds, whereby it stands still for about a quarter of this time. With gradual acceleration, braking and the conveying speed, high values are achieved because the conveyed cable consists of a short, i.e. H. light, loose cable loop 20 is pulled off.

The drive motor B of the conveyor 40 starts with a certain time delay compared to the drive motor A, namely only after the lowermost light barrier 44 has given the start signal. The increase in the speed curve, i. H. the acceleration is less steep than in the case of the drive A. During the ongoing cable production, the speed of the drive motor B oscillates between two speed levels and only returns to zero after a delay after the feed device 16 has been finally switched off. With stepless control of the drive motor B, it can also run during the ongoing cable production at an essentially constant, average speed which only needs to be readjusted slightly when unpredictable accidents occur in the cable transport.

What has been said for the control of the drive motor B also applies accordingly to the control of the drive motor C of the supply roll 12, except that in this case the start is delayed even further because it is only triggered when not only from the loop 20, but also a certain cable length has already been withdrawn from the buffer memory 24. Corresponding to the large inertial mass of the supply roll 12, the acceleration and braking values are still significantly lower than in the case of the conveyor device 40. During operation in the cable production, the drive of the supply roll 12 also oscillates between several speed levels or can be regulated continuously. After the feed device 16 has been finally switched off, the drive C of the supply roll 12 slowly runs out with a longer time delay. The cable length that is unwound is recorded in the buffer memory 24.

There is no jerky cable load in the device described, neither during start-up nor during operation. The strong acceleration of the cable in the region of the cable loop 20, however, is noticeable there by violent movement of the cable. It is therefore recommended to guide the cable loop 20 between two vertical walls 50, which for better observation z. B. may consist of acrylic glass. In addition, it is advisable to route the cable between the conveyor 40 and the entrance between the two vertical walls 50 in a pipe, not shown. In addition, because of the violent movements of the cable loop 20, it is recommended to arrange baffles or other guide elements next to the deflection roller 22, which ensure that the cable does not jump off the deflection roller 22.

It is understood that the role groups 26 and 28 can each consist of fewer or more than three roles. The number of rolls depends on the available height of the buffer memory 24 and on the desired memory content.

Finally, other suitable signal transmitters can of course also be used instead of the signal transmitters 44 and 48 mentioned as an exemplary embodiment. The current level of role group 28 can e.g. measure continuously with ultrasound so that a change upwards or downwards is detected immediately and thus the drive motor C of the supply roll 12 can be regulated.

Claims (8)

1. Device for feeding cables from a rotatingly drivable supply roll to an intermittent cable pulling cable assembly machine as a consumer
, characterized in that in the conveying direction of the cable (10) behind the supply roll (12) one after the other a buffer (24) receiving the cable (10) in the form of tensioned windings with variable circumference, a controllable conveyor (40) and a loose cable holding second buffer memory (20) are arranged. 2. Apparatus according to claim 1, characterized in that the first buffer memory (24) in the manner of a pulley block from two groups (26, 28) of rotatably mounted rollers (30-36) with a variable distance between the groups (26, 28) . 3. Apparatus according to claim 2, characterized in that an upper group (26) of rollers (30-36) is mounted in a fixed position and a lower group (28) of rollers on the cable (10) is loaded by a weight hanging. 4. Device according to one of claims 1 to 3, characterized in that the controllable conveying device (40) consists of one of the fixedly mounted rollers (36) and a cooperating with this, rotating movable pressure element (42), at least one of these two against the cable (10) pressed parts (36, 42) can be driven. 5. Device according to one of claims 1 to 4, characterized in that the second buffer memory contains a freely hanging cable loop (20) guided laterally between vertical guide walls (50). 6. Device according to one of claims 1 to 5, characterized in that the rolling speed of the supply roll (12) in dependence on the cable length contained in the first buffer memory (24) is controllable. 7. Device according to one of claims 1 to 6, characterized in that the conveying speed of the conveyor (40) in dependence on the cable length contained in the second buffer memory (20) is controllable. 8. Device according to one of claims 1 to 5, characterized in that the rolling speed of the supply roll (12) and / or the conveying speed of the conveyor (40) can be controlled directly as a function of the cable feed of the cable assembly machine (14, 16).

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