EP0565486B1 - Controlled card-clothing grinding - Google Patents

Description

The invention relates to a textile machine (for example a card) with a working element (for example a clothing) which has a decisive influence on the quality of the product of the machine, but whose condition deteriorates with increasing operating time (for example because of wear), which has a corresponding effect exerts the product quality. The textile machine is provided with a maintenance system that can be used during machine operation to counteract the deterioration of the condition of the work element.

State of the art

A textile machine (namely a card) of the type described above is shown in EP-A-322637. It has been suggested that the means of maintenance should be in constant use in order to constantly achieve the optimal quality. "Continuous" is to be understood in the sense that a grinding system or device is installed in the machine and is therefore always ready for operation (even while the machine is in operation) and not that grinding is carried out continuously during operation.

In the unpublished EP-A-497736 it has been proposed that the grinding element is continuously pulled over the set at predetermined (for example temporal) intervals which are dependent on the production performance and / or quality features. A grindstone can be moved to an end position (Fig. 3 or Fig. 7) that lies outside the working width of the card (the axial length of the clothing). The arrival of the grindstone in this end position is reported to a controller by a sensor.

The grinding according to EP-A-497736 can either be in operation, i.e. during carding or after the card has run out. The waiting times between grinding periods must be determined empirically. EP-A-004186 describes a grinder that can be attached to a card when it is necessary to grind a roller of the machine. The device comprises a carrier and a unit which can be moved back and forth on the carrier. The document deals on the one hand with the attachment of the device to the card and on the other hand with a construction of the unit, which favors the replacement of the grinding element.

The invention:
The aim of this invention is to make the use of systems according to EP-A-322637 more flexible, so that the capabilities of the system can be adapted to the requirements of use.

Starting from the device according to EP-A-0 322 637, this aim is achieved by the features of the characterizing part of claim 1, further advantageous embodiments being set out in the dependent claims.

Fig. 1

schematisch die Arbeitsbreite des Tambours einer Karde mit einem Schleifsystem nach EP-A-497 736,

Fig. 2.

eine erste Ausführung nach dieser Erfindung zum Einsatzsteuern eines Systems nach Fig. 1,

Fig. 3

ein Zeitdiagramm zur Erklärung der Einsatzsteuerung nach Fig. 2,

Fig. 4

eine schematische Darstellung eines Garniturzahns zur Erklärung der Schleifwirkung,

Fig. 5

eine schematische Darstellung einer zweiten Ausführung zum Einsatzsteuern eines Systems nach CH 267/91,

Fig. 6

ein weiteres Zeitdiagramm zur Erklärung der Wirkung eines Steuersystems nach Fig. 3, und

Fig. 7

ein Diagramm zur Erläuterung gewisser geometrischer Verhältnisse beim Schleifen.

Examples of the invention will now be explained in more detail with reference to the figures in the drawings. It shows:

Fig. 1

schematically the working width of the reel of a card with a grinding system according to EP-A-497 736,

Fig. 2.

1 shows a first embodiment according to this invention for operational control of a system according to FIG. 1,

Fig. 3

2 shows a time diagram for explaining the operational control according to FIG. 2,

Fig. 4

1 shows a schematic representation of a clothing tooth to explain the grinding effect,

Fig. 5

1 shows a schematic representation of a second embodiment for controlling a system according to CH 267/91,

Fig. 6

another timing diagram for explaining the effect of a control system of FIG. 3, and

Fig. 7

a diagram for explaining certain geometric relationships when grinding.

The structural details of the embodiment, which is shown schematically in Fig. 1, have already been set out in EP-A-497 736 and are not repeated here. 1 merely shows the surface 12 of the reel 10. A set (not shown) is fitted onto this surface 12, which is equipped with teeth and thus has a predetermined tip density (number of tips per unit area). This is indicated for only part 14 of the drum surface - but the drum is equipped with tips over its entire working width AB. In operation, the drum rotates about its axis (not shown), which means a movement of the teeth in the direction of arrow P.

The grindstone 16 according to EP-A-497 736 is shown in its end position L. The aforementioned sensor is shown at 18. By means of a drive motor 20 and a drive transmission means (not shown, for example a belt, the rail of a linear motor, a threaded spindle, etc.) and a holder (not shown) for the stone 16, the stone 16 can move in a direction perpendicular to the direction of movement P via the entire working width AB can be moved. The drum continues to rotate.

The dimension of the grindstone in its own direction of movement and its speed of movement can be selected in comparison to the speed of movement of the clothing teeth in the direction P that during a lifting movement of the whetstone from one side to the other of the drum each tooth of the clothing comes into contact with the whetstone a few times (eg 4 to 8 times). A single stroke movement (from one side of the reel to the other) is sufficient to "grind" all teeth, ie to exert a certain grinding effect. If this grinding effect is considered sufficient for certain purposes (as will be described later), a second layer L2 can be provided on the side of the reel from the end position L, where the grindstone 16 can remain without touching the clothing ( Waiting point).

It is now possible to define a "work cycle" for the system, which consists of an operating phase and a standby or waiting phase. The operating phase begins and ends in the end position (waiting point) - it accordingly contains a predetermined number (at least one) of a lifting movement from side to side of the working width. The duration of the operating phase depends on the number of strokes and the speed of the grinding stone. The duration of the standby phase is determined according to criteria that are described below.

Fig. 2 shows schematically the drum 10, Briseur 22, pickup 24 and the grinding system, which is indicated as a whole with the reference numeral 26. The system 26 comprises the grindstone 16 (FIG. 1), its holder (not shown), the drive motor 20 (FIG. 1) and the guide means (not shown) which guides the grindstone holder during a lifting movement. FIG. 2 also shows the drive motor 30 for the card, which sets the reel 10 in rotation, for example via a toothed belt 32, when the card is in operation. The motor 30 is controlled by signals from a card control 34 and reports its status back to this control 34. The card controller 34 also controls the grinding system 26, the grinding system being assumed in the example shown be provided with its own "sub-controller" 36, which carries out certain control functions autonomously on the basis of control commands from the main controller 34.

The main controller 34 is provided with a display 38 and a keyboard 40 for human-machine communication. This controller 34 also includes a time signal generator, which is indicated schematically at 42.

• a) die Anzahl Hubbewegungen einer Betriebsphase
• b) die Betriebsgeschwindigkeit derartiger Bewegungen (dies kann aber in der Untersteuerung 36 einprogrammiert sein)
• c) ein Startsignal zum Auslösen einer Betriebsphase.

The main controller 34 now issues the following control commands to the sub-controller 36:

• a) the number of strokes of an operating phase
• b) the operating speed of such movements (this can, however, be programmed in the under-control 36)
• c) a start signal for triggering an operating phase.

If only one waiting point (end position) is provided, each operating phase must of course include a certain number of double strokes (back and forth movements) from the end position.

The various phases (and the corresponding control commands or machine settings to be entered by the operator) will now be explained in more detail with reference to FIGS. 3 and 4.

3 is a timing diagram and is used to explain the duration of the standby phase. This diagram is not to be understood as a realistic representation of reality but as a purely fictitious diagram to explain principles.

In Fig. 3 the time is plotted on the horizontal axis and the tooth wear on the vertical axis. The "curve" K1 represents the increasing tooth wear during a period T1 of uninterrupted operation with a predetermined drum speed and a certain processed material. The "wear" is to be understood here as tooth wear, which leads to an impairment of the functionality of the tooth as a carding element. This is explained in more detail below with reference to FIG. 4. Under other operating conditions (drum speed, processed material) the wear is slower (e.g. after curve K2) or even faster (not shown), which leads to a steeper curve.

It is assumed in Fig. 3 that tooth wear has reached such a level at "N". that has to be sanded. This is not an absolutely valid level but is determined by the spinning mill depending on its production program (orders) at its own discretion. The decision is e.g. based on the delivered card sliver quality, e.g. according to the nits level. The (rather unrealistic) assumptions of the example shown result in a maximum operating time T1 for curve K1 and a maximum operating time T2 in curve K2 until the card for card grinding has to be stopped (without using an installed system) and partially dismantled. A considerable degree of tooth wear has been used over a large part of this period T1 (or T2). The grinding then causes an interruption U until the card can start operating again for a further period T1 (or T2).

By means of the continuous use of a built-in grinding system (such as system 26, FIG. 2) it is possible to keep the effective tooth wear (which is decisive for the product quality) to zero. But this was an expensive one Mode of operation because a certain degree of wear of the teeth remains without significant loss of quality, ie is quite bearable. Accordingly, under the operating conditions of curve K1, it is possible to let the card work, for example, over an operating period t, without this having a measurable effect on the product quality. At the end of this operating period t, the system 26 is actuated to cause a predetermined number of strokes of the grindstone, which brings the effective wear back to zero, without interrupting operation. The number of lifting movements is explained below with reference to FIG. 4.

The operating time t (without using the grinding system) is the same as the standby period of the grinding system 26. During this period, the grindstone waits in its end position or is ready for use in this end position. The period of time t can be entered by the operator into the controller 34 via the keyboard 40 (and can be called up again for checking purposes via the display 38). The "optimal" conditions can first be determined by test settings and the determined values can then be firmly entered for normal operation.

However, it may turn out that the "optimal" waiting period t decreases over the lifespan of a given set (ie until the card is refinished), ie the duration of this waiting period will often prove to be a function of the total operating time of the set. This can be taken into account by the controller 34 by means of an operating hours counter (not shown) and messages from both the motor 30 and the time signal generator 42. The motor 30 (which drives the drum) is only shown as an example as a source for the signals which drive the operating hours counter. Such signals could be taken from the customer drive and would have a closer relationship to material flow.

The correct function of the operating time and a start signal after re-garnishing must be entered by the operator, after which the controller 34 is able to determine the correct times for the use of the grinding system. At the end of each waiting period, the controller 34 sends a start signal to the sub-controller 36 in order to trigger the use of the grinding system. The subsequent use will now be explained with reference to FIG. 4.

Fig. 4 shows diagrammatically two teeth 50, 52 of a set and the direction of movement P (see also Fig. 4). The work of the tooth is performed at the top S and the wear at this point is decisive for the product quality. Carding technology (product quality) depends on the sharpness of the tip on the leading edge of each tooth 50, 52, etc. When grinding (all types), the tooth height is reduced in order to restore a sharp tip S1, S2 etc. on the front edge with every grinding operation. This can continue to a very low tooth height e.g. to the tip Sn (Fig.4), where the tip is in the transition to the next tooth.

The duration of the grinding operation or the work required for this depends on the tooth height, ie on the tooth cross-sectional area that has to be processed during grinding. This area is a function of the length 11, 12, 13 ..ln etc. (Fig.4), which increases with each grinding operation. As previously indicated, each grinding of a given set results in a subsequent operating period without grinding, the duration of this period decreasing with the number of grinding operations carried out. With "classic" grinding (without built-in grinding system) it is therefore worthwhile usually no longer work long before the tooth height has been reduced to the theoretical minimum. When using the classic grinding method (after which the machine has to be stopped for production, partially dismantled and equipped with a grinding device), three or four such grinding operations are normally carried out, after which the tooth may be ground down to point S2 (Fig. 4). Further grinding operations are not worthwhile with classic grinding - it is refurnished.

With a built-in grinding system e.g. system 26, Fig. 2, an increase in the amount of labor required to perform a sequence of grinding operations can be realized by a corresponding increase in the number of strokes per grinding operation (and still without interrupting production). The system only reaches its limit where it has to be continuously driven in operation with minimum operating speed (and / or with maximum adjustable contact pressure). The number of stroke movements per operating phase and the change with the total operating time of a given set can also be entered by the operator via the keyboard 40. The number of movements per grinding operation is then forwarded from the controller 34 to the controller 36 as a control command.

With a built-in system according to this invention, the drum 10 can be ground at full production speed. However, it may be necessary to change the drum speed for grinding compared to the production speed, e.g. to reduce. This can be effected by the controller 34 by means of a suitable control command to the motor 30.

If the motor 30 (or its "local" control) is designed such that it with discrete, predetermined Speeds works, can be switched from (or a) production speed to a "grinding speed". If the speed of the motor 30 (for example by means of a frequency converter) can be continuously adjusted within predetermined limits, the controller 34 determines an output frequency of the converter, which results in a suitable grinding speed of the reel.

Since the speed of a reel cannot be changed immediately (because of its inertia), a predetermined time delay must be inserted by the controller 34 between the "switching" of the motor 30 and the use of the grinding system 26. If the speed of the motor 30 is monitored and the control 34 is reported, the control 34 can be programmed such that it only controls the use of the grinding system when the grinding speed of the motor 30 is reached.

Fig. 5 shows a modified arrangement that can work as a self-adjusting machine. Since the machine itself (including its built-in grinding system) has not been changed compared to FIG. 2, the machine parts and the system 26 (with its "local" control 36) are indicated with the same reference symbols in both figures. 5 is a sensor (or a sensor arrangement) 54 which (or which) checks the product 56 of the card 40. The (or each) sensor 54 responds to a quality parameter that depends on the condition of the clothing 12 (FIG. 1), for example on the number of nits. A nit sensor for use in the exit of a card is known, for example, from DOS 3928279 or CH 669401 (or US 4953265). The theory of such a sensor system is known in the article "Automatic, objective nit counting on the cotton lid card" in the trade journal Textiltechnik 35 (1985) 5. Other possible sensor types are fiber stack measuring systems, CV measuring devices, devices for Measuring the short fiber content and sensors for thickness or thin spots in the card sliver.

The quality sensor could face the drum or the customer i.e. Check the quality of the product directly on the rotating machine element (e.g. number of nits).

However, it would also be possible to react to tooth wear (tooth shape) directly (rather than indirectly) via the product quality. A brightness sensor could, for example, be worn by the drum carrier to measure the brightness of the continuous clothing surface, which brightness changes with tooth wear. A distance sensor that responds to the distance to the teeth could serve a similar purpose.

The output signal of the sensor (or the sensor arrangement) 54 is supplied to the card controller 34A. This control differs from the control 34 (FIG. 2) only in the control program, which is tailored to the application in combination with the quality sensor or tooth condition sensor.

The operation of the arrangement according to FIG. 5 is explained below with reference to the time diagram in FIG. 6. In this figure, time is again drawn on the horizontal axis, but this time the number of nits as an example of a quality parameter on the vertical axis.

The number of nits Ao (Fig. 6) represents a lower limit that can be achieved with a new set in optimal condition. After the new start of material processing (currently to) with this new set, the number of nits increases as the set condition deteriorates due to wear of the teeth. The number of nits Ag represents for the user (for the spinning mill) represents a limit that must not be exceeded without intervention. The current number of nits (the actual value) is reported by the sensor (or the sensor arrangement) 54 to the controller 34A. As long as the actual value lies below the limit value Ag, the grindstone 16 (FIG. 1) of the system 26 remains in the waiting position (standby phase). At time t1, however, the sensor 54 reports that the limit value Ag has been reached and the control system accordingly triggers an operating phase of the system 26 (control command to the local control system 36).

Since the set is new, a few strokes of the grindstone 16 are sufficient to bring the teeth back into the optimal condition, i.e. the number of nits is brought back to the minimum limit value Ao. The subsequent standby phase (carding without intervention of the grinding system) lasts until time t2 (Wo t1 - to = t2 - t1). The number of nits then rose again to the limit value Ag and a second use of the grinding system 26 is triggered by the control 34A. In this first working period Pa of the set, it is therefore possible to repeatedly bring the number of nits back to the minimum value Ao.

With repeated use of the grinding system, however, the tooth condition remains impaired, so that the product quality (number of nits) can no longer be reduced to the optimal lower limit value Ao. In a medium working period Pm, for example, the number of nits can be improved at best by grinding to the value Am, and this with a steadily increasing tendency of this lower limit value. The standby intervals (carding without grinding) are shortened accordingly. In a final phase Pe, the lower limit for the number of nits approaches a value An, where it is no longer worth grinding repeatedly. The controller 34A then outputs an alarm, for example via the display 38 (FIG. 2), so that when there is a suitable Opportunity to re-garnish the drum.

In the embodiment according to FIG. 5, too, it is necessary to increase the amount of work when the set is repeatedly sanded (see FIG. 4). As in the embodiment according to FIG. 2, this can be controlled according to the accumulated operating hours of the set (i.e. according to an empirically determined formula which is entered by the operator) or also according to the output signal of the quality sensor or tooth condition sensor. In the latter case, a certain grinding operation is continued until a predetermined lower number of nits is reached again. From Fig. 6, however, it can be seen that this target value to be aimed for must be increased with the accumulated operating hours of the set (also according to an empirically determined formula). However, this still results in an additional monitoring option - if it is e.g. In the working phase Pm, when the grinding system 26 has been used for a given period of time, it has not proven possible to return to a (realistically) specified lower limit value for the number of nits, an alarm can be triggered in order to cause a check by the operating personnel.

The invention is not restricted to use on the drum set. It is also not limited to an arrangement according to which the grindstone is moved from side to side of the working width. Fig. 3 of the aforementioned EP 322637 shows an arrangement according to which the abrasive extends over the entire working width. The arrangement is particularly advantageous for grinding cover sets (flexible sets). Such a system can also be controlled according to the present invention in that the abrasive has a radial distance from the clothing in the ready position. A means of movement can then be provided to move the abrasive in the radial direction from the ready position to the operating point (in contact with the clothing).

The term "grindstone" in this context means a grinding element which is suitable for grinding a set, regardless of the material from which the element is made (e.g. ceramic or sintered metal).

Where the grinding element is moved from side to side across the working width, control of various "speed profiles" across this width can result. In the simplest example, the speed of movement of the element is kept constant, although this speed can be changed over time (with increasing operating hours since the last grinding operation) or can be adjustable. The operating speed can also be changed as a function of the distance to or from a waiting point, e.g. so that the speed reaches a maximum value in the middle between two waiting positions.

FIG. 7 schematically shows a single tooth 60 and the grindstone 62. The arrow 64 shows the direction of rotation of the reel or tooth 60 during production. Grinding during further production inevitably leads to "grinding against the tooth", i.e. the leading edge of the tooth hits the grindstone first.

In the classic grinding process, grinding is carried out “with the tooth”, ie the drum is rotated (in relation to its normal direction of rotation) in the opposite direction (arrow 66), so that the surface 68 comes into contact with the grinding stone 62 as the first part of the tooth. A built-in system according to this invention can also be used for "grinding with the tooth" - but this must be in the normal direction of rotation (64) moving drum initially brought to a standstill and then driven in the opposite direction (66) at a predetermined speed. In this case, production must be stopped.

Claims (17)

1. A textile machine with a processing element having a decisive influence on at least one quality parameter of the product of said machine, with the condition of the element deteriorating as the operating period increases and the product quality being impaired accordingly, and with a built-in maintenance element (16) which improves the condition of the processing element by treatment thereof in order to counteract the impairment of the product quality, characterized in that the maintenance element (16) is movable between a waiting position (L2) and an operating positon and that a control unit (34; 34A) is provided which controls or initiates the movement of the maintenance element depending on predeterminable parameters from the waiting position to the operating position and vice-versa.
2. A textile machine as claimed in claim 1, characterized in that the control unit (34, 34A) is provided with a program which effects the movement of the maintenance element (16) to the operating position or the return movement to the waiting position in accordance with the work cycle as defined by the program.
3. A textile machine as claimed in claim 2, characterized in that the work cycle comprises a predefined time interval (t) between successive operating assignments.
4. A textile machine as claimed in claim 3, characterized in that the time interval (t) is adjustable.
5. A textile machine as claimed in one of the preceding claims, characterized in that a sensor (54) is provided which responds to the said quality parameter and which generates a respective output signal.
6. A textile machine as claimed in one of the claims 1 to 5, characterized in that a sensor is provided which responds to the condition of the processing element and which generates a respective output signal.
7. A textile machine as claimed in claim 5 or 6, characterized in that the output signal of the sensor (54) is supplied to the control unit (34A) and the movement of the maintenance element (16) from the waiting position to the operating position is initiated depending on the output signal of the sensor.
8. A textile machine as claimed in claim 7, characterized in that the signal level (Ag) which initiates said movement is adjustable.
9. A textile machine as claimed in one of the preceding claims, characterized in that the processing element extends over a specific processing width (AB), that the maintenance element (16) extends only over a part of said processing width and that an operating assignment of the maintenance element comprises at least one movement of stroke over the whole processing width.
10. A textile machine as claimed in claim 9, characterized in that the speed of the movement of stroke is adjustable.
11. A textile machine as claimed in claim 9 or 10, characterized in that the control unit (34; 34A) is provided with a program which determines the number of movements of stroke over the whole processing width during every operating assignment.
12. A textile machine as claimed in claim 11, characterized in that the number of movements of stroke per operating assignment is adjustable.
13. A textile machine as claimed in claim 12, characterized in that the number of movements of stroke per operating assignment is set by the control unit (34; 34A) depending on the time in operation of the processing element.
14. A textile machine as claimed in claim 12, claim 4 and claim 5 or 6, characterized in that the number of movements of stroke per operating assignment is controlled depending on the duration of the time interval between successive operating assignments.
15. A textile machine as claimed in one of the previous claims, characterized in that the machine comprises a roller (10) provided with a clothing and that the processing element is the clothing and that the maintenance element (16) is a grinding means for the clothing.
16. A textile machine as claimed in claim 15 and claim 5, characterized in that the machine is a card and the sensor (54) is a nep sensor.
17. A textile machine as claimed in claim 15 and claim 5, characterized in that the machine is a card and the sensor (34) is an evenness sensor.

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