EP0093235B1 - Method of opening fibre bales - Google Patents

Description

The present invention relates to a method for removing fiber bales parked on a stand in the spinning mill, in which a removal member is moved back and forth over the bales and lowered before each pass, and the removed flakes are poured into a storage device and from there to the storage device are transported to the next processing stage, the weight of the amount of flakes transported into the storage unit per unit of time being somewhat greater than the amount of flakes transported out of the storage unit per unit of time, and when a maximum filling state of the storage unit is reached, a stop signal which stops the removal process and a minimum filling level of the A start signal which sets the removal process into operation is delivered.

Through the magazine "Melliand Textile Reports 1/1982, p. 15" it is already known to use microelectronics in spinning preparation for scanning the heights of bales and for delivering the specified removal depth per bale group. This known arrangement is a system for mixing different fibers.

In devices known in practice for the removal of fiber flakes from fiber bales placed on a standing surface, the removal member is repeatedly guided over a series of bales, the fiber material detected by the removal member being continuously removed as fiber flakes and, for example, through a suction channel. The removal device moves across the bales at a constant speed and its height is adjusted by a constant amount after each pass. As a result, a layer of flake material corresponding to this height adjustment is removed from the bales with each pass. The captured flake material is transported to a store and from there to the subsequent processing machines such as cards, stretchers and combing machines. It is desirable that these subsequent processing machines be continuously supplied with material. Therefore, flake material must always be present in the storage. This is ensured by the fact that a little more flake material is fed into the storage than the subsequent machines require. To avoid overfilling the storage, the removal process is stopped when the filling level of the storage exceeds a maximum value. If the filling level in the memory then drops below a minimum value as a result of the constant flake removal for the subsequent processing machines, the ablation process is switched on again. This results in periodic shutdown and commissioning of the removal process, i.e. of flake production. An optimal mode of operation is one in which the removal process works approximately 80-90% of the time and stands still approximately 20-10% of the time. This time reserve of 10-20% is required and experience has shown that it is sufficient, among other things, to carry out maintenance work or, when working with two alternate rows of bales, turning the removal device 180 ° from the removed row of bales to the full row of bales .

The bales to be removed are not equally dense across the board. They are the densest in their central area. This means that when the top and bottom parts of a bale are removed, less flakes are delivered in terms of weight than when the middle part is removed. With regard to the statements made above, this means that at the beginning and at the end of the bale less material is fed to the storage unit per unit of time in weight than when the bale is removed in the central region. Thus, the removal machine works at the beginning and end of the bale for longer periods of time than when removing the central area of the bale.

In order to ensure an uninterrupted delivery of flakes from the storage in the known devices, the optimal standstill value of 10-20% of the operating time is provided at the beginning and end of the bale. As a result, the downtimes of the removal roller when removing the central area of the bale become too long. This is uneconomical because it means that the blowroom machines are underused.

This disadvantage is to be avoided by the present invention. This is characterized in that the start and stop signals are fed to a switching arrangement which generates a monitoring signal which is dependent on the duration of the time intervals given by the start and stop signals and is fed to a computer together with a predetermined signal defining a predetermined time interval which forms a control signal which is dependent on the monitoring signal and the desired signal and which is fed to control the weight of the flakes removed from the fiber bale by the removal member per unit of time to a device controlling the removal process of the removal member.

According to the invention, the removal of the dense part of the bale, which forms the majority of the flake material of the bale, takes place in relatively thin layers. This means a more gentle bale opening with smaller flakes. The influence of the inhomogeneity of the bales is practically eliminated. On the other hand, the ongoing adaptation to the optimal downtimes in comparison to the known removal machines and with a flake quality which is the same as that achieved with these known machines can be used to increase the overall production of the removal machine.

• Fig. 1 eine Ansicht einer Ballenabtragseinrichtung mitzwei Ballenreihen, von oben gesehen und
• Fig. 2 eine schematische Darstellung einer Steuerung gemäss der Erfindung.

The invention will be explained in more detail below using an exemplary embodiment and the drawing. In the latter is

• Fig. 1 is a view of a bale removal device with two rows of bales, seen from above and
• Fig. 2 is a schematic representation of a controller according to the invention.

Fig. 1 shows a series of bales 11, which are parked on a stand. Above these bales, a removal member 12 is arranged, which is carried by a carrier 13. A motor is provided in the carrier 13, by means of which the removal member 12 can be set in rotation. The carrier 13 is movable back and forth along rails 14. The removal member 12 is also adjustable in height. A conveying channel 15 serves to receive the flakes removed from the bales 11 by the removal roller 12 and to feed them to a storage unit 16. From the storage unit 16, the fiber flakes pass through a duct 17 to subsequent processing machines.

A monitoring system 21 is located on the memory 16, which delivers a start signal a when a predetermined, minimum filling state of the memory 16 is reached and a stop signal e when a predetermined, maximum filling state of the memory 16 is reached. The signals a and e pass through an electrical line 22 to an electrical circuit 23, in which a monitoring signal y is generated, which leads to the carrier 13 via a line 24. The signal y is dependent on the time intervals present between the immediately successive start and stop signals a and e. 25 with a device is designated, which is used to deliver the longer cable length of the cable forming the line 24 required when the carrier 13 moves to the left, and which receives the cable which is released again when the carrier 13 moves to the right. The drawing shows the reference symbols for the signals on the lines through which they are transmitted.

1 shows a second row of bales 18 drawn in broken lines. In such an embodiment, the bales 18 are brought up and put down during the removal of the bales 11. After the bales 11 have been removed, the removal member 12 is pivoted through 180 ° about the axis of rotation 33, whereupon the removal of the row of bales 18 is started. After these have been removed, the removal member is pivoted back onto a new row of bales 11 and these are removed, etc.

The circuit 23 shown in FIG. 1 comprises a switching arrangement 26 shown in FIG. 2, a line 27 and a computer 28. The memory 16 with the monitoring system 21, the channels 15 and 17 and the lines 22 and 24 are again shown . Flake material 32 is shown with oblique hatching. The removal machine 30 is represented as a unit schematically by a block. A nominal signal j is fed to the computer 28 through a line 31.

This determines the duration of the time intervals during which the removal machine 30 is in the working state and at a standstill, i.e. in a non-flake producing state. The computer 28 forms a control signal s from the target signal j and the monitoring signal y supplied by the switching arrangement 26, which control signal s is fed via line 24 to a device (not shown) which controls the removal process of the removal member 12 and is present in the removal machine 30 or in the carrier 13 becomes. In addition, the start and stop signals a and e are fed directly from the monitoring system 21 to the removal machine 30 via the lines 22, 27 and 24.

In operation, the carrier 13 moves back and forth with the removal member 12 on the rails 14. In this case, the flake material is removed from the bales 11 by the rotating removal member 12. This flock material 32 passes through the conveying channel 15 into the storage device 16. After each passage of the removal member 12, it is lowered by a certain amount, so that with each passage it removes a layer of fiber material, the thickness of which corresponds to the amount by which the removal member 12 has been lowered , is equal to. As mentioned at the beginning, the amount of flake material 32 entering the storage 16 through the conveying channel 15 per unit time is somewhat larger than the amount of flake material 32 removed through the passage 17 per unit time. As soon as a predetermined, maximum filling state is reached in the storage device 16, it delivers the monitoring system 21 a stop signal e.

This passes directly to the removal machine 30 via the lines 22, 27 and 24 and causes the flake production or the removal process to be stopped. In the meantime, the removal of flake material 32 from the storage 16 continues. When a predetermined, minimal filling state of the memory 16 is reached, the monitoring system 21 emits a start signal a. Like the stop signal e, this passes directly to the removal machine 30 via the lines 22, 27 and 24 and causes the machine to be moved again.

In normal operation of the removal machine 30 there are working time intervals T _a from each filling state a up to the immediately following stop signal e and downtime intervals T _s lasting from each stop signal e to the immediately following filling state a. A working time interval T _a and a downtime time interval T _s connected to this are referred to as an operating cycle. A monitoring signal y is formed in the switching arrangement 26, which is dependent on the time intervals T _a and T _s , ie is a function of the variables T _a and T _s . The target signal j defines a predetermined, desired relationship of the values T _a and T _s to one another. If T _a and T _s have to satisfy the relationship mentioned at the beginning, according to which in an operating cycle (of the duration (T _a + T _s )) the working time interval T _a is four times the idle time interval T _s (ie T _a forms 80% and T _s forms 20% of the duration of an operating cycle), the target signal j has a certain value. With a change in the values of T _a supplied by the monitoring system 21 with respect to T _s , the signal y changes.

In the computer 28, the monitoring signal y and the desired signal j are compared with one another and a control signal s is generated which is a function of the deviation of the values T _a and T _s from their desired mutual relationship, which is predetermined by the signal j. This signal s controls the device provided in the removal machine 30 and controls the removal process of the removal member 12 in such a way that the flake production, ie the weight of the flakes removed by the removal member 12 per unit of time from the fiber bales 11 is changed in the sense that the desired relationship between T. and T _s given by the target signal j is obtained.

According to the invention, the control signal s effects at the transition of the removal from the upper to the middle region of the bale 11, for example by reducing the height adjustment of the removal member 12 per pass, i.e. per operating cycle, a reduction in weight of the flake material captured by the roller 12 per unit of time. Correspondingly, the control signal s at the transition of the removal from the middle to the lower region of the bales 11, for example by increasing the height adjustment of the removal member 12 per pass, causes an increase in the weight of the flake material recorded by the roller 12 per unit of time.

Such a weight reduction or enlargement of the amount of flake material removed per unit of time is achieved not only by the reductions or enlargements of the reduction mentioned just before the passages of the removal member 12. Instead of increasing or decreasing the reduction, e.g. the time intervals of the successive passages of the removal member 12 can also be reduced or enlarged. The change in the transit time of the moving removal member 12, e.g. by changing the driving speed of the carrier 13, a possibility of variation.

By regulating the removal machine 30 by means of the control signal s, as already mentioned, the weight of the flakes removed from the fiber bales 11 by the removal member 12 per unit of time is changed. If this weight is increased, the memory 16 is filled more quickly, so that the number of downtime intervals T _s increases. If this weight is reduced, the number of these intervals T _{s is} reduced.

In a special embodiment of the invention, a monitoring signal y is formed in the switching arrangement 26, which is proportional to the expression T _a / (T _a + T _s ). This means that under the special conditions in which the working time intervals T _{a are} 80% and the idle time intervals T _{s are} 20% of the duration of an operating cycle, the expression T _a / (T _a + T _s ) has the value 0 , 8 owns. In such a case, a control signal is formed in the computer 28 from the target signal j and the monitoring signal y, by means of which the removal machine 30 is adjusted to the mentioned value 0.8 by changing the amount of flakes removed per unit of time. The use of the expression T _a / (T _a + T _s ) as the basis for the formation of the control signal gives the advantage of a simple and reliable circuit.

Claims (6)

1. Method of extracting flocks from fibre bales placed on surface in the spinning mill, in which method a flock extracting member is moved to and fro above the bales and is lowered before each passage and the extracted flocks are fed into a receiver and are transported therefrom to the next processing stage, the quantity of flocks in terms of weight per unit time fed into the receiver being somewhat larger than the quantity of flocks taken from the receiver per unit time, a stop signal (e) for stopping the extraction process being produced when a maximum fill condition of the receiver is reached and a start signal (a) for setting the extraction process in operation being produced when a minimum fill condition of the receiver is reached, characterised in that these signals (a, e) are fed to a circuit arrangement (26) which produces a monitoring signal (y) dependent upon the length of the time intervals (Ta, Ts) defined by the start signals (a) and stop signals (e) and fed to a processor (28) together with a reference signal (j) defining predetermined time intervals, in which processor a control signal (s) dependent on the monitoring signal (y) and the reference signal (j) is produced, the control signal being fed to a device controlling the extraction process of the extracting member (12) to control the weight of flocks extracted per unit time from the bales by the extracting member (12).

2. Method according to claim 1, characterised in that the monitoring signal (y) is proportional to the expression Ta/(Ta+Ts), Ts representing the stop time intervals between the stop signals (e) and the start signal (e), and Ta representing the operating time intervals between the start signals (a) and the stop signal (e) immediately succeeding each start signal (a).

3. Method according to claim 2, characterised in that the value of the reference signal (j) is so chosen that the expression Ta/(Ta+Ts) has approximately the value 0,8.

4. Method according to claim 1, characterised in that the height adjustment of the extraction member (12) effected on succeeding passages is adjusted in magnitude by the control signal (s) to control the weight of the flock quantity delivered per unit time by the extracting member (12).

5. Method according to claim 1, characterised in that the time periods of the passages of the extracting member (12) over the bales (11) is adjusted by the control signal (s) to control the weight of the flock quantity delivered per unit time by the extracting member (12).

6. Method according to claim 5, characterised in that the variation of the time periods of the passages of the extracting member (12) is effected by varying the speed of travel of the carrier (13).

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