EP0555731A1 - Method and apparatus for continuous cutting of a strand or tow material - Google Patents

Abstract

An improved method and an improved apparatus for the continuous cutting of strip-like or strand-like material, especially of chemical-fibre tows, are described. The apparatus according to the invention comprises a cutting wheel (1) having a plurality of cutting knives (3) which are arranged circularly in a knife mounting (2) and which are arranged at a predetermined distance from one another corresponding to the desired stack, at least one pressure roller (4), for achieving a cutting pressure, acting on the cutting knives (3), on the wound strip-like or strand-like material, an opening and closing device (5), by means of which the pressure roller (4) can be moved a predetermined distance away from the cutting wheel (1) or towards the cutting wheel (1), a setting member (6), by means of which a predetermined distance between the pressure roller (4) and the cutting knife (3) nearest to this pressure roller (4) can be set, a damping member (7), by means of which, in cooperation with the setting member (6), the pressure force exerted by the pressure roller (4) on the strip-like or strand-like material resting on the knives (3) can be adjusted so that the cutting capacity of the apparatus remains virtually unchanged within a predetermined interval of pressure forces, and a distance-measuring device (8), by means of which the distance between the pressure roller (4) and the cutting knife (3) nearest to the pressure roller (4) can be monitored. The cutting method carried out by using this apparatus is characterised by a good constancy of the cutting capacity, by a long service life of the cutting knives and by a uniform quality of the cut material. <IMAGE>

Description

The present invention relates to an improved device for the continuous cutting of strip-like or strand-like material, in particular man-made fiber cables, and an improved method for cutting this band-like or strand-like material.

Methods and devices for the continuous cutting of strip-like or strand-like material are known per se.

A cutting device for fiber cables is known from EP-A-305,057. This device contains a knife basket with cutting knives and a pressure roller that presses the fibers against the cutting knives. This device is characterized in that it contains a means by which the angular position of the cutting wheel with respect to the pressure roller can be determined, that it contains a means by which the contact pressure exerted by the pressure roller on the cutting knives can be determined, and that it contains a means by which the quality of the cutting knives can be determined depending on the angular position of the cutting wheel and the pressure exerted on the cutting knives. With the known device it is therefore possible to monitor the quality of the cutting knives during operation and thus the quality of the material cut.

DE-A-3,311,190 describes a device for cutting ribbon-like or strand-like material, which comprises a knife basket with two knife support disks arranged axially one above the other with approximately knife length spacing, between the corresponding spacing in the desired stack a plurality of radially outwardly directed knives are held, and at least one pressure roller is associated with them outside at a distance to achieve a radially inward-acting cutting pressure on the wound fiber cable. The known device is characterized in that more than just one pressure roller is assigned to a knife basket. With the known device, a large output of cut material is available, without this resulting in a greater load on the cutting knives.

From DE-AS-2,720,918 a method and a device for monitoring the cut of a staple fiber cutting machine is known, in which the cutting ability of each individual cutting blade is determined and a signal is generated when the pressures are too high or too low, which can be used to switch off the staple fiber cutting machine . The device described contains two measuring elements with which the position of the cutting knife and the deflection of a pressure roller is determined. A targeted control of the pressure force during the cutting process is not proposed.

Furthermore, from DE-AS-2,144,104 a method and a device for cutting spinning cables is known, in which a spring force is exerted for pressing a pressure roller against the spinning cable, the pressure roller being moved against the spring pressure during the cutting process and the device reaching it a maximum permissible pressure force limit is switched off. A targeted monitoring of the distance between the cutting knife and the pressure roller and a readjustment of this distance during the cutting process cannot be found in this publication.

In the operation of these previously known devices, however, it has been found that problems can arise during the continuous cutting of strip-like or strand-like material which cannot be solved completely satisfactorily with these devices. For example, the cutting performance of the device and the quality of the cut material can change as a result of the wear of the knife edges during continuous operation. It can also be in the In individual cases it may be necessary to adapt the contact pressure to the properties of the material to be cut, such as fiber type, preparation or moisture; it would therefore be desirable if the pressure could be easily adapted to changing cutting conditions by the pressure roller. Furthermore, it occurs during the continuous cutting operation that the material to be cut has imperfections, such as knots or thick spots. Such imperfections can lead to a short or long-term load on the cutting knives, whereby knife breaks can occur under certain circumstances. Such knife breaks can result in the knives falling out of the holder and cutting no longer taking place at the point in question, as a result of which excessively long fibers are produced. Furthermore, the winding material can pile up on the cutting device in continuous operation after a knife break, in which the knife does not fall out of the holder.

Furthermore, when operating such devices, in particular in the production of short-cut fibers, it must be taken into account that the pressure rollers must apply an additional pressure in addition to the cutting pressure, with which the further transport of the cut stacks along the knives into the interior of the cutting wheel is accomplished. At the beginning of the cutting process with sharp knives, the proportion of the pressure to be used for the actual cutting process is relatively small compared to the proportion of the pressure to be used for the further transport of the cut stacks along the knife. In the course of the cutting process, the knives blunt, and the portion of the cutting pressure can be a multiple of the portion of the pressure to be used for the further transport of the cut stacks along the blades. In practice, therefore, these known devices are expediently operated such that at the beginning of the cutting process, the pressure rollers are brought so close to the cutting wheel that they rest on the respective stop and the pressure is set so high that the position of the pressure rollers is maintained throughout Cutting process remains practically unchanged.

Based on the methods and devices of the type mentioned at the outset, the object of the invention is to provide an improved method and an improved device with which it is possible in a simple manner to control the quality of the cutting knives, the quality of the to keep the cut goods constant over a long period of time, to increase the service life of the cutting knives, to adapt the cutting conditions to the different materials in a simple manner and to minimize the problems in the case of defects in the cut goods.

The invention is based on the knowledge that there are special advantages when cutting such a good thing, if the pressure roller is suspended and if it is in normal operation at a constant distance from the cutting wheel. The constancy of the distance is desirable since, when this distance is varied, the material already wound on the cutting wheel can shift perpendicular to the cutting direction, so that transverse forces can occur which should be avoided if possible. The pendulum suspension is desirable because it allows a gentler cutting process, especially in cutting devices with multiple pressure rollers.

The device according to the invention is characterized in particular in that the force acting on the material to be cut can be changed in a simple manner as a function of the knife quality with the distance between the knife and the pressure wheel being as constant as possible and in that means are provided with which the knife breakage is as simple as possible or other irregularities, an error message is displayed to the operating personnel and / or the device is stopped.

• a) ein Schneidrad (1) das eine Vielzahl von kreisförmig in einer Messerhalterung (2) angeordneten Schneidmessern (3) aufweist, welche jeweils in einem vorbestimmten dem gewünschten Stapel entsprechenden Abstand angeordnet sind,
• b) mindestens eine Anpressrolle (4) zur Erzielung eines auf die Schneidmesser (3) einwirkenden Schneidedruckes auf das aufgewickelte band- oder strangförmige Gut,
• c) eine Öffnungs- und Schließvorrichtung (5), mit der die Anpreßrolle (4) um einen vorbestimmten Abstand von dem Schneidrad (1) wegbewegt oder auf das Schneidrad (1) hinbewegt werden kann,
• d) ein Stellglied (6), mit dem ein vorgegebener Abstand zwischen der Anpreßrolle (4) und dem dieser Anpressrolle (4) nächstkommenden Schneidmesser (3) eingestellt werden kann,
• e) ein Dämpfungsglied (7), mit dem in Zusammenwirken mit dem Stellglied (6) der von der Anpressrolle (4) auf das auf den Messern (3) aufliegende band- oder strangförmige Gut ausgeübte Anpreßdruck so eingestellt werden kann, so daß die Schneidleistung der Vorrichtung innerhalb eines vorgegebenen Intervalles von Anpressdrucken praktisch unverändert bleibt, und
• f) eine Abstandsmessvorrichtung (8), mit der der Abstand zwischen der Anpreßrolle (4) und dem der Anpressrolle (4) nächstkommenden Schneidmesser (3) überwacht werden kann.

This object is achieved with a device for the continuous cutting of strip-like or strand-like material, in particular of chemical fiber cables

• a) a cutting wheel (1) which has a plurality of circularly arranged in a knife holder (2) cutting knives (3), each in a predetermined the distance corresponding to the desired stack is arranged,
• b) at least one pressure roller (4) to achieve a cutting pressure acting on the cutting knives (3) on the wound strip-like or strand-like material,
• c) an opening and closing device (5) with which the pressure roller (4) can be moved away from the cutting wheel (1) by a predetermined distance or can be moved towards the cutting wheel (1),
• d) an actuator (6) with which a predetermined distance between the pressure roller (4) and the cutting blade (3) closest to this pressure roller (4) can be set,
• e) an attenuator (7) with which, in cooperation with the actuator (6), the contact pressure exerted by the pressure roller (4) on the band-like or strand-shaped material resting on the knives (3) can be adjusted so that the cutting performance the device remains practically unchanged within a predetermined interval of contact pressures, and
• f) a distance measuring device (8) with which the distance between the pressure roller (4) and the cutting blade (3) closest to the pressure roller (4) can be monitored.

The devices according to the invention can each contain the opening and closing device (5), the actuator (6) and the damping member (7) as separate components. However, these components can also be partially or completely combined in one component.

The cutting wheel (1) in the device according to the invention can be designed in all known ways. The cutting edges of the knives can point in the direction of the axis of rotation of the cutting wheel. Cutting wheels of this type are e.g. in DE-A-2,720,918.

The knife basket of the device according to the invention is preferably designed as described in DE-A-3,311,190. It is therefore a cutting wheel (1), which consists of a knife basket (2) with two axially one above the other with approximately Knife length spacing from each other is provided between the knife support disks, between which a plurality of radially outwardly directed knives (3) are held in the desired stack.

Conventional devices, such as described in DE-A-3,311,190, can be used for this purpose as a pressure roller for achieving a cutting pressure on the wound fiber cable in the direction of the knife edges. It is possible to equip the device according to the invention with only one pressure roller. However, several pressure rollers are also possible.

Any device suitable for this purpose can be used as the opening and closing device (5). These are usually movement devices with the aid of which machine parts can be moved over larger distances in the cm or dm range for retooling or maintenance of the cutting device. Examples of these are mechanically, hydraulically, pneumatically or electromechanically driven devices.

The device according to the invention contains at least one, preferably an actuator (6) with which a predetermined distance between the pressure roller (4) and the cutting wheel (1) can be set. With this actuator (6) an initial state of the cutting device is defined at the start of operation and during operation this actuator serves to reset the distance which changes during operation to the originally specified value. Any device suitable for this purpose can be used as the actuator (6). These are usually movement devices with the aid of which machine parts can be moved over smaller distances in the mm range or below. Examples of this are - as in the case of the opening and closing device - appropriately adapted mechanically, hydraulically, pneumatically or electromechanically driven devices.

Any device suitable for this purpose can be used as an attenuator (7). The attenuator (7) is a vibratory mechanical system; this is characterized by a force-elongation characteristic. This component can be, for example, a spring or a spring assembly, or any other device with which a force-expansion characteristic corresponding to a spring can be specified, for example a computer-controlled mechanical or electromechanical component with which a desired force-expansion Curve can be set.

Springs or spring assemblies, for example spiral, leaf or disc springs, are preferably used as the damping member (7). It can be tension or in particular compression springs. Disc springs are very particularly preferably used, since these can be used to easily produce Kratt strain characteristics of the most varied steepness.

In addition to the setting of the contact pressure on the band-shaped or strand-like material resting on the knives (3), the damping member also serves for the effective weakening of force impacts of the pressure roller (4), which are triggered by a bottleneck between the cutting device and the pressure roller when it passes through a defect.

Any device suitable for this purpose can be used as the distance measuring device (8) with which the distance between the pressure roller and the cutting device can be monitored. With this distance measuring device (8) either a direct measurement can be carried out or an indirect measurement is preferably carried out with which the distance can be deduced. Indirect measurement is preferred because the position of the distance measuring device in the cutting device can be freely selected in this case.
The distance measuring device can be, for example, a line marking which is attached to any component which changes in length during the operation of the cutting device and which is compared with a fixed location, for example a location on the housing.

However, it can also be any other device suitable for this purpose. Examples of this are plunger coils, induction coils, displacement, strain gauges, ultrasonic or laser light distance measuring devices.

In the case of several pressure rollers, it is generally sufficient if only one distance measurement is carried out.

The device according to the invention is preferably equipped with two pressure rollers which are arranged in particular at an angle of approximately 120 to approximately 270 ° from one another, based on the diameter of the cutting wheel. Very particularly preferably, two pressure rollers (2) are provided, which are arranged approximately opposite one another.

Particularly preferred embodiments of the device according to the invention are shown in subclaims 2 to 16.

The contact pressure exerted on the strip-like or strand-like material lying on the knives is mainly applied by the pressure roller. This contact pressure is set at the start of operation, among other things, by the choice of the predetermined distance between the pressure roller and the cutting device. During the continuous cutting operation, the material to be cut is wrapped around or on the knife basket and is transported through the constriction between the pressure roller and the cutting device. This creates a cutting force and the inner layer of the material to be cut is cut by the knife edges and transported out of the cutting wheel through the spaces between the knives. As a result of wear of the knife edges during operation, the cutting speed decreases and the amount of material wound on the cutting device increases. As a result, the distance between the pressure roller and the cutting device increases. The device according to the invention provides an attenuator with which, in cooperation with the actuator, the contact pressure exerted by the pressure roller on the strip-like or strand-like material resting on the knives is set can be, so that the cutting performance of the device remains practically unchanged within a predetermined interval of contact pressures.

• i) Einstellen eines vorbestimmten Abstandes zwischen der Anpreßrolle (4) und den Schneidkanten der Schneidmesser (3) mit Hilfe eines Stellgliedes (6), wobei dieser Abstand so zu wählen ist, daß die Anpreßrolle (4) gegenüber dem Schneidrad (1) pendeln kann,
• ii) Überwachung besagten vorbestimmten Abstandes mit Hilfe einer Abstandsmessvorrichtung (8), und
• iii) Einstellen des von der Anpreßrolle (4) auf das auf den Messern (3) aufliegende band- oder strangförmige Gut ausgeübten Schneiddruckes durch ein mit dem Stellglied (6) zusammenwirkendes Dämpfungsglied (7) in einer solchen Weise, daß die Schneidleistung der Vorrichtung innerhalb eines vorgegebenen Intervalles von Anpreßdrucken praktisch unverändert bleibt.

The invention also relates to a method for the continuous cutting of strip or strand-shaped material, in particular man-made fiber cables, in which the material to be cut is connected to a cutting wheel (1) which has a plurality of cutting knives (3) arranged in a circle in a knife holder (2), which are each arranged at a predetermined distance corresponding to the desired stack, brought up and cut by a force acting in the direction between the material and the cutting edges of the cutting knife (3), for which purpose a winding with winding layers lying one on top of the other is continuously formed in this way that the new material coming to the knife roller forms the winding layer lying furthest away from the cutting edges, and that the winding layer lying directly on the cutting edges is continuously cut by the cutting edges of the cutting knives, the between the good and cutting edges of the cutting knife he (3) acting force is mainly generated by means of a pressure roller (4) acting on the winding layer lying furthest away from the cutting edges, comprising the steps:

• i) Setting a predetermined distance between the pressure roller (4) and the cutting edges of the cutting knife (3) with the aid of an actuator (6), this distance being chosen so that the pressure roller (4) can oscillate relative to the cutting wheel (1) ,
• ii) monitoring said predetermined distance using a distance measuring device (8), and
• iii) Adjusting the cutting pressure exerted by the pressure roller (4) on the band-shaped or strand-like material resting on the knives (3) by means of a damping element (7) interacting with the actuator (6) in such a way that the cutting performance of the device within of a predetermined interval of contact pressures remains practically unchanged.

Particular embodiments of the method according to the invention are presented in subclaims 18 to 20.

The device and the method according to the invention are described by way of example with reference to the following FIGS. 1 to 7.

Fig. 1 shows an embodiment of the device according to the invention with a pressure roller in supervision.

Fig. 2 shows a further embodiment of the device according to the invention in supervision, in which the attenuator is designed in a special way.

3 and 4 each show an embodiment of the device according to the invention with two pressure rollers in supervision.

5 shows a preferred embodiment of the device according to the invention with two pressure rollers in supervision, in which the distance between the cutting wheel and the pressure rollers can be kept constant over a control path.

Fig. 6 shows a further preferred embodiment of the device according to the invention with four pressure rollers in supervision.

FIG. 7 also shows a preferred embodiment of the device according to the invention, in which the opening and closing device, actuator and damping element are implemented in one device.

The device according to FIG. 1 contains a cutting wheel (1), which consists of two knife support disks (2) arranged one above the other with an approximately knife length spacing from one another (only shown sketchily here), between which a large number of radially outwardly directed spacings in the desired stack Knives (3) are held. The cutting wheel (1) is over the Axis of rotation (12) connected to the housing (13). The fiber cable to be cut is wound spirally on the cutting wheel (1). While the innermost layer lies directly on the cutting edges of the knives (3), the pressure roller (4) first presses on the outermost layer, which is fixed in position relative to the rotating cutting wheel (1) at a substantially constant distance from the axis of the cutting wheel. As a result of the cable wound onto the cutting wheel with tension, a radially inwardly directed cutting pressure acts on each of the individual knives arranged in the area of the pressure roller (4), which cuts the fibers of the innermost layer on the cutting edges of the knives. The resulting stacks are pushed further radially inwards into the cutting wheel (1) by the subsequent fibers and then transported vertically downwards.

The pressure roller (4) is held by the lever arm (10) which is attached to the housing (13) via a joint (11) and which is connected to the axis (15) of the pressure roller (4). This lever arm (10) is in turn articulated to a linkage (9) via which the opening and closing device (5), the actuator (6) and the damping member (7) act on the lever arm (10). The linkage (9) is articulated at its other end to the housing (13). In this embodiment, the lever arm (10) also contains a distance measuring device (8) with which the distance between the pressure roller (4) and the cutting wheel (1) can be monitored. In the device shown, this is done by indirectly measuring the distance between the distance measuring device (8) and the stop (14), which in turn is attached to the housing (13). The stop (14) serves to prevent direct contact of the pressure roller (4) with the cutting edges of the cutting blades (3). The length of the linkage (9) can be changed by the opening and closing device (5), the actuator (6) and the damping member (7). The opening and closing device (5) serves to move the pressure roller (4) away from the cutting wheel (1) in order to be able to change the knife, for example, in the event of operational interruptions. The actuator (6) and the damping element (7) are used in particular to maintain operating conditions that are as constant as possible during the cutting process.

At the beginning of the cutting process, the actuator (6) can be used to set a certain length of the linkage (9) and thus a predetermined distance between the pressure roller (4) and the cutting wheel (1) (e.g. the outer edge of the knife closest to the pressure roller). The actuator can be a mechanically, pneumatically, hydraulically or electromechanically operated device, for example a screw connection with which the length of the linkage (9) can be varied.

The damping member (7) - at a predetermined distance between the pressure roller (4) and the cutting wheel (1) depending on the length of the linkage (9) - regulates the pressure of the pressure roller (4) on the cable wound on the cutting wheel. The attenuator (7) is therefore characterized by a force-expansion characteristic. This can be, for example, a spring or a fader package or any other device with which a force-stretching characteristic corresponding to a spring can be specified, for example a computer control with which a desired force-stretching characteristic can be set.

The distance measuring device (8) can be, for example, a line marking on the linkage (9), the position of which is compared with a fixed point on the housing (13) and thus allows conclusions to be drawn about the change in length of the linkage (9). But it can also be any other device with which the change in length of the linkage (9) and thus the distance between the pressure roller (4) and the cutting wheel (1) can be checked.

At the beginning of the cutting process, a basic setting is set by means of the actuator (6) through a certain length of the linkage (9), thus a certain distance between the pressure roller (4) and the cutting wheel (1) is specified and the damping member (7) is pretensioned. This distance is checked using the distance measuring device (8). The distance between the pressure roller (4) and the cutting wheel (1) in the individual case can be set by a person skilled in the art with the help of Preliminary tests can be determined. This distance will depend, among other things, on the material to be cut, on the quality of the knives at the beginning of the cutting process and on the course of the force-expansion characteristic of the damping element (7). Once the desired distance has been set, the device is put into operation by winding the material to be cut onto the knife basket. As soon as a sufficient contact pressure has built up through the action of the pressure roller (4) on the outer layers of the winding, the cutting process begins. The blades of the knives wear out due to the continuous operation of the device. As a result, the thickness of the roll increases and thus the distance between the pressure roller (4) and the cutting wheel (1). This also increases the length of the linkage (9). This is only possible by changing the length of the damping member (7), which increases the force exerted by the linkage (9) on the lever arm (10) and thus also increases the contact pressure exerted by the pressure roller (4).

The change in length of the linkage (9) is indicated by the distance measuring device (8) and can be reversed by actuating the actuator (6). As a result, the force exerted by the damping member (7) via the linkage (9) on the lever arm (10) is increased again, and thus also the contact pressure exerted by the pressure roller (4). A new stationary operating state has now been achieved, which is characterized by an increased contact pressure compared to the initial conditions and a practically equal distance between the pressure roller (4) and the cutting wheel (1). As a result of the increased contact pressure, the decreasing cutting speed of the knives that wear out during operation is compensated for. The adaptation process described can be carried out several times during operation and, in particular, can be regulated without transition, the cutting speed of the device being able to be kept practically unchanged within a predetermined interval of contact pressures. The service life of the knives can thus be increased considerably.

With the device according to the invention, advantages can be obtained not only in normal cutting operation, but also in the event of defects in the material to be separated, operation can generally be carried out with fewer risks. Flaws, such as thick spots or knots, can lead to knife bridges in conventional cutting devices, since high contact pressures are usually exerted on the knives in the area of such flaws. If, on the other hand, such a defect wound on the cutting device passes through the bottleneck between the pressure roller and the cutting device, the length of the linkage (9) is immediately increased and at the same time the contact pressure increases as a result of the extension of the damping member (7). However, this increase in the contact pressure is not as great as in conventional cutting devices which do not allow a brief variation in the distance between the contact roller (4) and the cutting wheel (1). The risk of knife breakage can thus be reduced with the device according to the invention. In addition, the variation of the contact pressure with changing length of the linkage (9) can be adjusted within wide ranges by the choice of the steepness of the force-expansion characteristic of the damping member (7), so that the risk of a knife breakage can also be reduced by this measure.

The device according to FIG. 2 is constructed similarly to the device according to FIG. 1. Here too, the cutting wheel (1), pressure roller (4), opening and closing device (5), actuator (6), distance measuring device (8) and linkage (9) are provided, while instead of the lever arm (10) in Fig. 1 in the present If a lever arm (16) is provided. The linkage (9) and lever arm (16) are connected to the housing (13) and also to one another as in the device according to FIG. 1. 1, the attenuator (7) is not installed in the linkage (9), but the lever arm (16) acts simultaneously as an attenuator (7). This can be achieved, for example, in that the lever arm (16) is designed as an elastic member, for example as a leaf spring. Otherwise, the mode of operation and operation is the same as for the device according to FIG. 1.

3 is a preferred embodiment with two pressure rollers (4). The structure corresponds essentially to the structure of the device according to FIG. 1. There are a cutting wheel (1), two pressure rollers (4), an opening and closing device (5), an actuator (6), a damping element (7), one Distance measuring device (8), a linkage (9), two lever arms (10) and two stops (14) are provided. The lever arms (10) are each articulated on one side to the housing (13). On the other side, the lever arms (7) are articulated to the linkage (9), so that a double arm seesaw is formed. The distance is measured in the device shown by measuring the distance between the distance measuring device (8) and a marking (18) which is attached to a rod (18a). The rod (18a) is articulated to a lever arm (10) and is freely movable at one end between the two lever arms (10). In the embodiment shown, it lies near its other end on a stop (17) on the second lever arm (10), so that it can move freely at one end when the distance between the two lever arms (10) changes.

A particular advantage of this construction can be seen in the fact that when imperfections of the material to be cut pass through the constriction between a pressure roller and the cutting device, the sudden deflection of this pressure roller is partially compensated for by an opposite movement of the second pressure roller. This further reduces the risk of a knife break.

The device according to FIG. 4 essentially corresponds to the device according to FIG. 3. Here, only the lever arms (10) are each centrally attached to the housing (13) and the pressure rollers (4) are each attached to the end of a lever arm (10).

A very particularly preferred embodiment of the cutting device according to the invention is shown in FIG. 5. In principle, this is the construction with two pressure rollers (4) according to FIG. 3. There are a cutting wheel (1), two pressure rollers (4), an opening and closing device (5) and an actuator (6), an attenuator (7), a distance measuring device (8), a linkage (9) and two lever arms (10) are provided. In this embodiment, the distance measuring device (8) is attached to the housing (13) and acts on the actuator (6) via a controlled system (21) and a servo motor (20). With the help of this arrangement, the position of one end of the linkage (9) is practically always kept constant during the operation of the device. Furthermore, in this embodiment of the device, a tension or pressure sensor (19) is provided, with which the contact pressure between the pressure roller (4) and the cutting wheel (1) can be measured directly. In the present case, this pressure sensor is attached directly to the attenuator (7). But it can also be attached to the linkage (9) at any other point. The tension or pressure sensor (19) is advantageously coupled to a switch-off device (not shown), with which the device is automatically switched off when a predetermined final value of the contact pressure is reached (in stationary operation or when a fault has passed). Furthermore, two stops (14) are shown in FIG. 5, with which it is to be prevented that the minimum distance between the pressure rollers (4) and the cutting wheel (1) is not exceeded. Instead of the tension or pressure sensor (19), the automatic shutdown can also be carried out by a limit switch which is actuated by the damping element (7).

6 shows a further preferred embodiment of the cutting device according to the invention. In principle, this is a construction according to FIG. 3. In this variant, however, four pressure rollers (4) are provided, which are each coupled in pairs. 6 are a cutting wheel (1), four pressure rollers (4), an opening and closing device (5), an actuator (6), an attenuator (7), a distance measuring device (8), a linkage ( 9) and two lever arms (10) are provided. In this embodiment, the distance measuring device (8) is attached to one of the lever arms (10) and measures the distance between its position and a stop (14). Two of the pressure rollers (4) are articulated to a lever arm (10) via a bracket (22). The connection is made via the axis (23). This embodiment is again compared to the construction according to Figure 3 improved by the fact that when imperfections of the material to be cut pass through the constriction between a pressure roller and the cutting device, the suddenly required additional cutting power is distributed over several pressure rollers. This further reduces the risk of a knife break. Furthermore, the service life of the cutting knives increases, since the cutting pressure can be reduced for a given cutting performance, since a cutting pressure is exerted on the material to be cut at four points per revolution.

7 shows an embodiment of the device according to the invention in which the opening and closing device (5), actuator (6) and damping member (7) are realized in one component. An embodiment is shown with only one pressure roller (4); However, the embodiments with two or more pressure rollers (4) can of course also be designed in this way.

7, a cutting wheel (1), a pressure roller (4), a linkage (9) and a lever arm (10) are provided. Linkage (9) and lever arm (10) are articulated with each other and each connected to the housing (13). A stop (14) prevents the pressure roller (4) from hitting the cutting edges of the cutting knives (not shown here). The linkage (9) contains a pneumatic cylinder (24), the cylinder body of which forms part of the linkage (9) and the piston (25) of which is connected to the other part of the linkage (9). One interior of the interior of the pneumatic cylinder (24), which is divided by the piston (25), is connected to a pipeline (29) which acts as a control path and, via a pneumatic control unit (27), to a nozzle (28), the outlet opening of which against the lever (10) is directed, and is connected to a feed line (26).

The nozzle (28) together with the pneumatic control unit (27) and pneumatic cylinder (24) act together as an opening and closing device (5), actuator (6), damping member (7) and distance measuring device (8). In the continuous cutting operation, there is a preselected distance between the pressure roller (4) and Cutting wheel (1) set. A certain pressure in the pneumatic control unit (27) for the pneumatic cylinder (24) is predetermined by a gas, for example air, through the feed line (26) and part of the gas can - depending on the distance of the nozzle (28) from the lever arm ( 10) - escape through the nozzle (28). An equilibrium state is established, which is characterized by a specific position of the piston (25) in the cylinder body of the pneumatic cylinder. If there is now a deflection of the lever arm (10) as a result of wear of the cutting knives or as a result of the occurrence of a thick point between the cutting knives and the pressure roller (4), the escape of the gas through the nozzle (28) will be made difficult at some point because the lever arm (10) approaches the nozzle opening, whereby the pressure in the pipeline (29) builds up. The pressure in one half space of the pneumatic cylinder (24) thus increases. This has the direct consequence that the piston moves in the direction of the half-space with the lower pressure, whereby the lever arm (10) moves away from the opening of the nozzle (28) by the action of the linkage (9) and thus the outlet for the gas facilitated. This creates a new steady state; with further changes in the pressure conditions between the pressure roller (4) and the cutting wheel (1) this state changes again in the manner described. The pneumatic cylinder (24) can also be operated as an opening and closing device (5) if, for example after the cutting process has been interrupted, the pressure roller (4) is to be moved away from the cutting wheel (1). The force-travel characteristic of the cutting device can be influenced accordingly by the design of the pneumatic cylinder (24).

With the device according to the invention and the method according to the invention, practically any ribbon-like or strand-like material can be cut continuously and in a simple manner into stacks, such as fibers made from natural polymers, inorganic substances and synthetic polymers. The invention can preferably be used for cutting chemical fiber cables, in particular for cutting fiber cables made of polyester, polyamide, polyacrylonitrile or viscose. The cut material is characterized by a high uniformity of the individual stacks and by a constant quality of the cut ends, which does not change significantly even after a long period of operation.

A preferred field of application of the device according to the invention relates to the production of short cut fibers. These are usually fibers with a stack length of approximately 2.5 to 8 mm, in particular 4 to 6 mm.

With the device according to the invention it is possible to produce short cut fibers over a long period of time and with practically constant quality.

Particularly in the production of short cut fibers, it is advisable to design the cutting wheel and the knives in a special way.

For example, the arrangement of the knives in the knife basket is preferably selected such that the shaft formed by the individual knife blades increases in the transport direction of the cut stacks. This measure makes it easier to transport the cut stacks along the knives.

Furthermore, a certain ratio of the width of the cutting knife to the thickness of the fiber cable to be cut has to be selected. It must be ensured that the material to be cut on the cutting wheel does not exceed a certain thickness.

Cutting knives with asymmetrically arranged cutting edges are preferred for the production of short cut fibers. These can be knives, the cutting edge of which - viewed from the narrow side of a knife blade - is located directly on the left or right upper edge of the knife; however, they can also be knives in which the cutting edge - viewed from the narrow side of a knife blade - is not between the left or right upper edge of the knife but in the middle between the two edges. Knives with asymmetrically arranged cutting edges (one-sided or asymmetrically ground knives) have different forces perpendicular to the axial direction when cutting on the two ends of the stack, so that the cut stacks separate between the knife blades during further transport tilt and a lower force must be used for further transport.

Another preferred measure in the production of short-cut fibers is the selection of the smallest possible distance between the cutting wheel and the pressure roller. A distance of approximately 0.5 to 2 mm is preferably selected.

A cutting preparation can also be used in the production of short cut fibers, provided that this does not adversely affect the desired product properties. This is in particular a preparation that improves the sliding properties of the fibers. The use of fiber cables that are as dry as possible generally also facilitates the cutting process.

Claims (25)

Device for the continuous cutting of ribbon or strand-shaped material, in particular of chemical fiber cables, comprising a) a cutting wheel (1) which has a plurality of cutting knives (3) arranged in a circle in a knife holder (2), each of which is arranged at a predetermined distance corresponding to the desired stack, b) at least one pressure roller (4) to achieve a cutting pressure acting on the cutting knives (3) on the wound strip-like or strand-like material, c) an opening and closing device (5) with which the pressure roller (4) can be moved a predetermined distance away from the cutting wheel (1) or can be moved towards the cutting wheel (1) d) an actuator (6) with which a predetermined distance between the pressure roller (4) and the cutting blade (3) closest to this pressure roller (4) can be set, e) an attenuator (7) with which, in cooperation with the actuator (6), the contact pressure exerted by the pressure roller (4) on the band-like or strand-shaped material resting on the knives (3) can be adjusted so that the cutting performance the device remains practically unchanged within a predetermined interval of contact pressures, and f) a distance measuring device (8) with which the distance between the pressure roller (4) and the cutting roller (4) closest to the cutting knife (3) can be monitored. Apparatus according to claim 1, characterized in that the cutting wheel (1) consists of a knife basket (2) with two knife support disks arranged axially one above the other with approximately knife length spacing, between which a plurality of radially outwardly directed knives in the desired stack (3) are kept. Apparatus according to claim 2, characterized in that at least one pressure roller (4) is associated with the cutting wheel (1) at a distance outside in order to achieve a radially inward-acting cutting pressure on the wound strip-like or strand-like material. Device according to one of claims 1 to 3, characterized in that the minimum distance between the pressure roller (4) and the cutting edges of the knife (3) closest to this pressure roller (4) is adjustable by means of a stop (14). Device according to one of claims 1 to 4, characterized in that a lever arm (10), which is articulated to the housing (13), is provided for the pressure roller (4) and is articulated to a linkage (9) via which the opening and the closing device (5), the actuator (6) and the damping member (7) act on the lever arm (10). Device according to one of claims 1 to 5, characterized in that two pressure rollers (4) are provided, which are preferably arranged approximately opposite one another. Device according to claim 6, characterized in that the two pressure rollers (4) are each attached to a lever arm (10) which is articulated to the housing (13) and each lever arm (10) is articulated at one end to the linkage (9) via which the opening and closing device (5), the actuator (6) and the damping member (7) act on the lever arm (10). Device according to one of claims 1 to 4, characterized in that four pressure rollers (4) are provided, each of which is articulated in pairs via a holder (22) to a lever arm (10) and that the lever arms (10) are each articulated to the housing (13) and each lever arm (10) is articulated at one end to the linkage (9) via which the opening and closing device (5), the actuator (6 ) and the damping element (7) act on the lever arm (10). Device according to one of claims 1 to 8, characterized in that the damping member (7) is a spring or a spring assembly. Apparatus according to claim 9, characterized in that the spring or springs are a plate spring or plate springs. Device according to one of claims 1 to 10, characterized in that the actuator (6) is a screw connection with which a predetermined length of the linkage (9) can be adjusted and which is optionally moved with the aid of a servo motor (20). Device according to one of claims 5 to 11, characterized in that the linkage (9) in addition to the actuator (6) and the damping member (7) additionally has a monitoring device which switches off the device when a predetermined final value of the contact pressure is exceeded. Device according to claim 12, characterized in that it has a tension or pressure sensor (19). Device according to claim 13, characterized in that the distance measuring device (8) acts on the actuator (6) via a control path (21) and a servo motor (20), so that essentially the same distance between the device is practically during the entire operating state of the device Pressure roller (4) and cutting wheel (1) is specified. Device according to one of claims 1 to 4, characterized in that opening and closing device (5), actuator (6) and damping member (7) are realized in one component, a cutting wheel (1), at least one pressure roller (4), a linkage (9) and a lever arm (10) are provided, linkage (9) and lever arm (10) are articulated to one another and each connected to the housing (13), a stop (14) is provided which prevents the pressure roller (4) strikes the cutting edges of the cutting knives, the linkage (9) contains a pneumatic cylinder (24), the cylinder body of which forms part of the linkage (9) and the piston (25) of which is connected to the other part of the linkage (9), whose by the piston (25) divided an interior is connected to a pipe (29) which acts as a control section and via a pneumatic control unit (27) with a nozzle (28), the outlet opening of which is directed against the lever (10), and one Supply line (26) is connected. Device according to one of claims 2 to 15, characterized in that two or more cutting wheels (1) are arranged directly one above the other and are provided with knives which run continuously from one wheel to the other. Device according to one of claims 1 to 16, characterized in that the arrangement of the knives in the knife basket is selected so that the shaft formed by the individual knife blades increases in the transport direction of the cut stacks. Device according to one of claims 1 to 17, characterized in that cutting knives with asymmetrically arranged cutting edges are used. Process for the continuous cutting of strip-like or strand-like material, in particular chemical fiber cables, in which the material to be cut is connected to a cutting wheel (1) which has a multiplicity of circular shapes in a knife holder (2) arranged cutting knives (3), which are each arranged at a predetermined distance corresponding to the desired stack, brought up and cut by a force acting in the direction between the material and cutting edges of the cutting knives (3), for which purpose from cutting material, a winding with superposed winding layers is continuously formed in such a way that the new material coming to the knife roller forms the winding layer lying furthest away from the cutting edges, and that the winding layer lying directly on the cutting edges is continuously formed by the cutting edges of the cutting knives is cut, the force acting between the material and the cutting edges of the cutting knives (3) being generated mainly by means of a pressure roller (4) acting on the winding layer lying furthest away from the cutting edges, comprising the steps: i) Setting a predetermined distance between the pressure roller (4) and the cutting edges of the cutting knife (3) with the aid of an actuator (6), this distance being chosen so that the pressure roller (4) can oscillate relative to the cutting wheel (1) , ii) monitoring said predetermined distance using a distance measuring device (8), and iii) Adjusting the cutting pressure exerted by the pressure roller (4) on the band-shaped or strand-like material resting on the knives (3) by means of a damping element (7) interacting with the actuator (6) in such a way that the cutting performance of the device within of a predetermined interval of contact pressures remains practically unchanged. Method according to claim 19, characterized in that the material to be cut is brought to a knife basket (2) with a plurality of cutting knives (3) pointing in the radial direction and is cut by a force acting in the radial direction between the material and the knife basket (2), why continuously from the material to be cut Winding with radially superposed winding layers is formed in such a way that the material newly tapering to the knife roller forms the winding layer of the winding lying radially furthest away from the cutting edges, and that the radially innermost winding layer is continuously cut by the cutting edges of the cutting knives , the force acting between the material and the knife basket being generated mainly by means of a pressure roller (4) acting on the winding layer of the winding lying radially furthest away from the cutting edges. Method according to one of claims 19 to 20, characterized in that additionally as a step iv) the cutting pressure is monitored with a tension or pressure sensor (19) and the cutting device is switched off when a predetermined maximum value of the cutting pressure is reached. Method according to one of claims 19 to 21, characterized in that by means of the distance measuring device (8), a control path (21) and a servo motor (20) acts on the actuator (6), so that practically during the entire operating state of the device in essentially one and the same distance between the pressure roller (4) and the cutting wheel (1) is specified. Method according to one of claims 19 to 22, characterized in that a predetermined distance of 0.5 to 2 mm is selected between the pressure roller (4) and the cutting edges of the cutting knives (8). Method according to one of claims 19 to 23, characterized in that a dry fiber cable or a fiber cable provided with a sliding preparation is used as the material to be cut. Use of the device according to claim 1 for the production of short cut fibers.

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