EP0022042B1 - Machines for dipping fabrics - Google Patents

Abstract

1. A self-contained machine for the preliminary fullwidth and tensionless dipping of a fabric prior to its introduction into a treatment installation, of the kind comprising, on the one hand, two superposed rows of drums (6, 7) between which the fabric (1) is returned in order to pass between ramps (10) for the spingling of the vertical lengths (1') defined on this fabric by the said rows, and, on the other hand, a series of electric motors (9) for effecting the drive under a constant torque of the drums (6) of one of the rows, characterized in that placed on the feed circuit of the motors (9), of the type having variable speed and constant torque, is an auto-transformer (20) directly controlled by a compensating roller (14) disposed, in the manner known "per se", at the outlet of the drums (6, 7) of the two rows with a view to being subjected to alternating displacements as a function of the difference in the respective working speeds of the machine and of the treatment installation fed by this latter.

Description

We know that when leaving the printing machines it is often necessary to wash the fabrics in order to get rid of the coating or "gum" which covers their printed side. These coatings or gums can be very resistant and it is then necessary to have recourse, prior to the washing proper, to a presoak operation intended to soften the layer and to impregnate the thickness of the fabric in order to favor the action. subsequent cleaning.

This presoak is usually carried out using equipment placed upstream of the washing installation. This apparatus operates continuously and obviously should not involve any slowing down of the operation of the washing installation, so that it contains a very long length of fabric, of the order of several tens of meters. Thus it has been proposed in particular to send the fabric vertically between two superimposed rows of drums associated with spray bars. Each drum obviously exerts a significant braking effect, so that when, for example by means of suitably arranged feed rollers, it is called up at the outlet of the presoaking apparatus, it frequently happens that by as a result of the excessive tension thus applied to the fabric, it folds longitudinally at the same time as it inadmissibly shrinks.

So we have thought (see in particular DE-A-2 551 084) to make machines in which the drums of one of the rows are driven individually under a constant torque, these drive means being placed under dependence a reciprocating compensating roller. However, the solutions proposed were so complex that the total cost of the machine was very high, while the reliability of the assembly was greatly reduced.

The present invention proposes to remedy this drawback by allowing the production of an autonomous pre-soaking machine which ensures the treatment of fabrics without tension and offshore and whose construction is remarkably simplified.

The machine according to the invention, of the kind comprising on the one hand two superimposed rows of drums between which the fabric is returned in order to pass between ramps for the spraying of the vertical strips defined on said fabric by said rows, and on the other share a series of electric motors to ensure the drive, under a constant torque of the drums of one of these rows, is characterized in that on the supply circuit of electric motors, of the variable speed and constant torque type is placed a self-transformer directly controlled by a compensating roller arranged, in a manner known per se, at the outlet of the drums of the two rows in order to be subjected to alternating displacements according to the difference in the respective working speeds of the machine and the treatment plant supplied by it.

• Fig. 1 est une coupe verticale montrant schématiquement l'agencement général d'une machine de prétrempage établie conformément à l'invention.
• Fig. 2 illustre à plus grande échelle le système pour la commande des moteurs électriques d'avance.

The appended drawing, given by way of example, will allow a better understanding of the invention, the characteristics which it presents and the advantages which it is capable of providing:

• Fig. 1 is a vertical section schematically showing the general arrangement of a presoak machine established in accordance with the invention.
• Fig. 2 illustrates on a larger scale the system for controlling electric advance motors.

In fig. 1 the reference 1 designates the fabric to be treated by presoaking. This fabric 1, taken from a reserve shown diagrammatically in 2, is returned) ur to successively cross a station 3 for the unrolling of the selvedges and a centering station 4, the devices or mechanisms provided at said stations 3 and 4 being well known in practical and therefore does not require any detailed description.

At its exit from the centering station 4 the fabric 1 passes inside a tank 5 possibly filled with a liquid impregnation product, then it is guided to be successively returned vertically between two overlying rows of drums referenced 6 and 7, which thus determine on said fabric a series of vertical portions or strips oriented in parallel to each other. The lower drums 7 are arranged above a tank 8, while each of the upper drums 6 is connected to an independent electric drive motor 9 of the multi-pole asynchronous type, at constant torque.

Each upper drum 6 is surmounted by a spraying ramp 10, all of the ramps 10 of the machine being supplied from a pipe 8a provided on the lower tank 8; the latter collects the liquid which after spraying by the ramps 10 trickles along the strips 1 'and it also receives a supply via an auxiliary pipe 12, the excess flowing through an overflow 8b.

On leaving the last upper drum 6, the fabric 1 is returned upwards, not a perforated drum 7, but by a compensating roller 14 (fig. 1) provided substantially at mid-height between the rows 6 and 7. This roller 14 is carried by lateral arms 15 articulated in the manner of flails on pivots 16 and it is the vertical displacements of said roller 14 which control the adjustable speed of the drive motors 9.

To this end and as illustrated in fig. 2 one of the two pivoting arms 15 extends beyond its pivot 16 opposite the roller 14 and on this protruding part 15a is attached to the end of a cable 17 suitably returned by pulleys 18 and provided at its opposite end with a tension counterweight 19 which only partially balances the weight in overhang of the aforementioned roller. On this cable 17 is fixed the mobile armature, shown diagrammatically at 20a, of an auto-transformer 20 connected to the electrical circuit which supplies all of the motors 9.

It should be noted that a switch 21 is also provided on this electrical supply circuit, the movable member 21a a of which is linked to one of the two pivoting arms 15 and is designed to selectively actuate four contactors suitably connected to the circuit. aforementioned, as will be better understood when we explain below the operation of the machine according to the invention.

The fabric 1 returned upwards by the compensating roller 14 is recalled downwards by a final drum 6 'driven by a motor 9' (fig.1) connected to the same general circuit as all of the motors 9. It passes through then a widening mechanism 22, advantageously constituted by two cylinders or "screws" with oblique grooves, then a centering device 23 of conventional type, before finally being returned horizontally at 24 to enter the washing installation associated with the presoak machine.

In terms of operation, it is understood that the maintenance of the fabric 1 across the whole of the machine is ensured by the widening mechanisms 3 and 22 provided at the ends of said machine. The tests demonstrated that any untimely shrinking of the fabric 1 during the presoak was radically avoided, at the same time as the centering devices 4 and 23 operated for the correct retention of said fabric in the central part of the drums. This fabric is perfectly presented at the entrance to the treatment facility.

It will also be understood that the drive of this fabric 1 through the whole machine is carried out without tension since said fabric is moved by the upper drums 6 on each of which a constant torque is exerted, whatever the speed of rotation of the motors 9. Consequently the fabric 1 is only subjected to its own weight and to a force just necessary to overcome its inertia. The drive speed is controlled by the vertical movements of the compensating roller 14; be appreciated in fact that, depending on the installation needs provided downstream of the machine, that is to say in ⁼ function call of tissue at the outlet cylinder 24, this roller 14, wrapped in the last fold of fabric, will go up or down depending on whether the working speed of the presoak machine is lower or higher than that of the associated installation. These vertical displacements are transmitted by the cable 17 to the auto-transformer 20 which consequently controls all of the motors 9 and 9 'and thus the speed of rotation of each of them, so that the machine regulates it - even without any manual intervention.

If, however, the difference in working speeds is very important at a given time, the movable member 21a of the switch 21 actuates one or the other (depending on whether the working speed of the presoak machine is higher or on the contrary lower than that of the treatment installation) of the two central contactors, thus short-circuiting the auto-transformer 20 by directly supplying the motors 9 and 9 'at most in one case, and by cutting the auto transformer 20, therefore the supply of motors 9 and 9 ', in the other case. The machine "thus quickly" recovers the difference in speed and the automatic regulation by the auto-transformer 20 can resume in a very short period of time.

If, despite this all-or-nothing command, the "recovery" does not take place and the speed difference continues to increase, the movable member 21a comes to bear against one or the other of the two lateral contactors of the switch 21 which causes the machine to stop completely. This provides an effective security system.

It goes without saying that the assembly can be fitted with various accessories capable of improving the guiding of the tissue to be treated, its regular course and its spraying. In addition, and although driving each drum 6 by a separate motor constitutes the best solution, it is obviously possible to connect several of these drums to the same motor. It will also be understood that the invention is applicable to any presoak operation of fabrics, in particular with a view to bleaching them.

It should be noted that the cost price of the machine according to the invention is much lower than that of conventional machines. The constant torque motors 9 and 9 ′ are inexpensive and the compensating roller and auto-transformer system which controls them avoids the need for complicated and expensive control devices.

It should moreover be understood that the above description has been given only by way of example and that it in no way limits the field of the invention from which one would not depart by replacing the execution details described by all other equivalents.

Claims (2)

1. A self-contained machine for the preliminary fullwidth and tensionless dipping of a fabric priorto its introduction into a treatment installation, of the kind comprising, on the one hand, two superposed rows of drums (6, 7) between which the fabric (1) is returned in order to pass between ramps (10) for the sprinkling of the vertical lengths (1') defined on this fabric by the said rows, and, on the other hand, a series of electric motors (9) for effecting the drive under a constant torque of the drums (6) of one of the rows, characterised in that placed on the feed circuit of the motors (9), of the type having variable speed and constant torque, is an auto-transformer (20) directly controlled by a compensating roller (14) disposed, in the manner known »per se«, at the outlet of the drums (6, 7) of the two rows with a view to being subjected to alternating displacements as a function of the difference in the respective working speeds of the machine and of the treatment installation fed by this latter.

2. A machine according to claim 1, characterised in that mounted on the mechanism (15-16-17) which connects the compensating roller (14) to the movable armature (20a) of the auto-transformer (20) is a switch (21) which short circuits or breaks this latter automatically when the differences in speeds reach a predetermined threshold.

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