Device for Introducing a Running Material Web into a Tenter Machine

Abstract

A device (1) is used for introducing a running material web (3) into a tenter machine. The device (1) comprises at least one tiltable cheek (12) which receives the material web (3). This cheek (12) is tilted by at least one control element (13) by means of at least one actuator (19). This control element (13) engages on the one hand on the cheek (12) and on the other hand on the frame (17). Angle sensors (32) record the angle between the cheek (12) and the control element (13) as well as between the frame (17) and the control element (13). These angles are delivered to calculation means (66′) for calculating the difference of the two recorded angles.

Claims

1. A device for introducing a running material web into a tenter machine, said device comprising at least one tiltable cheek which receives said material web, said at least one cheek being tiltable by means of at least one control element having at least one actuator which engages on one hand on a fixed frame and on other hand on said at least one cheek, and measuring means for recording a tilt angle of said at least one cheek being provided, wherein said measuring means comprise angle sensors, of which one records an angle between said at least one cheek and said at least one control element and one records an angle between said at least one control element and said frame, and calculation means which calculate a difference of the two recorded angles are provided.

2. The device according to claim 1, wherein said at least one of said angle sensors is an analogue sensor.

3. The device according to claim 1, wherein said at least one of said angle sensors is a digital sensor which can output more than two different angle values.

4. The device according to claim 3, wherein said at least one of said angle sensors can output more than four different angle values.

5. The device according to claim 1, wherein said calculated difference is compared with at least one first threshold value, further tilting of said at least one cheek being prevented when said first threshold is exceeded.

6. The device according to claim 1, wherein said calculated difference is compared with at least one second threshold value, said at least one cheek being tilted into a location which lies closer to a neutral location in said web running direction when said second threshold is exceeded.

7. The device according to claim 1, wherein said calculated difference is compared with at least one third threshold value, an alarm signal being transmitted to said tenter machine when said third threshold is exceeded.

8. The device according to claim 1, wherein said device comprises at least one further sensor, which records said angle of said at least one cheek relative to said frame.

9. The device according to claim 8, wherein said further sensor is used for plausibility checking of said angle sensors.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0018] Other advantages and characteristics of this invention will be explained in the detailed description below with reference to the associated figures that contain several embodiments of this invention. It should however be understood, that the figure is just used to illustrate the invention and does not limit the scope of protection of the invention.

[0019] FIG. 1 shows a three-dimensional representation of a device for introducing a running material web into a tenter machine,

[0020] FIG. 2 shows a three-dimensional representation of a control element,

[0021] FIG. 3 shows a view of the control element according to FIG. 2 from behind, and

[0022] FIG. 4 shows a schematic representation of a circuit diagram of the evaluation unit.

DETAILED DESCRIPTION OF THE INVENTION

[0023] A device 1 according to FIG. 1 is used to introduce a material web 3 running in a web running direction 2. This material web 3 is in this case delivered to a tenter machine (not represented in the figure). For this purpose, the device 1 comprises a deflecting roll 4, which deflects the material web 3 into the desired web running direction 2. This deflecting roll 4 is followed by splaying devices 5, which comprise motor-driven threaded spreading rolls 6. These threaded spreading rolls 6 are in frictional contact with the running material web 3 and exert onto the material web 3, by the rotation and a thread pitch, forces which are directed towards edges 7 and which splay these edge regions. The effect achieved in this way is that the material web 3 is substantially smooth and does not have curled edges. This is important in particular for knitwear, which generally has a tendency to curling in the edge regions.

[0024] Immediately after the splaying devices 5, the running material web 3 is delivered to chains 8 which are guided around deflecting rollers 9. These chains may, in contrast to the representation according to FIG. 1, be arranged not only horizontally but also vertically. Furthermore, it is also conceivable to arrange the chains 8 in a plane arranged obliquely with respect to the horizontal. Of these deflecting rollers 9, only the pair on the feed side is respectively represented. The chains 8 are in this case configured endlessly and are motor-driven, in such a way that the speed thereof coincides with the web running speed of the running material web 3. The chains 8 comprise clamping arms 10 which grip the running material web 3 between their clamping jaws 11 with a friction and/or form fit. As an alternative, the chains 8 may also be equipped with pins. In this way, the running material web 3 has its movement synchronised in the respective regions of its edges 7 with the movement of the chains 8. In order to be able to precisely receive the running material web 3 and deliver it to the tenter machine, the chains 8 are held on tiltably mounted cheeks 12 so that the edges 7 of the running material web 3 run exactly onto the chains 8. In this way, location guiding of the running material web 3 is achieved, which is important for the subsequent tenter machine.

[0025] The location of the cheeks 12 is regulated in such a way that the respective edge 7 of the material web 3 is aligned with the chain 8. For this purpose, edge sensors 52 which record the edge length of the material web 3 and deliver it to a regulator (not represented) are provided. These edge sensors 52 are firmly connected to the cheeks 12, so that they record the edge 7 of the material web 3 relative to the cheek position. In this way, the edge sensors 52 immediately indicate a feed error of the edge 7 relative to the cheeks 12. This feed error is adjusted to the setpoint value 0 by the regulator in order to achieve optimal feed, in particular without distortion, of the material web 2 to the cheeks 12 in the stabilised regulating state.

[0026] In order to set each of the cheeks 12, a control element 13 is respectively provided, which is tiltably supported by means of a tilting bearing 14 on the respective cheek 12 and is tiltably supported by means of a tilting bearing on a frame 17. An actuator, the pinion 15 of which meshes with a rack 16 that is fitted on the frame 17 fixed to the machine, is provided in this control element 13. By rotation of the pinion 15, it rolls along the rack 16 so that a pinion shaft is displaced transversely with respect to the web running direction 2. Because of the coupling of the control element 13 to the cheek 12, the latter is thereby tilted in order to adapt an angle of attack of the chain 8 to the web running direction 2.

[0027] The specific structure of the control element 13 will be explained in more detail with the aid of FIGS. 2 and 3. The control element 13 comprises a housing 18, on which the tilting bearing 14 for support on the cheek 12 is held. An actuator 19, which drives the pinion 15 represented in FIG. 4 by means of gearing 20, is furthermore provided in the control element 13. Opposite the pinion 15 there is an interlock 21 which is formed by ball bearings 22. This interlock 21 forms a counter-bearing for the control element 13, which engages behind the frame 17 and thereby ensures that the pinion 15 meshes correctly with the rack 16. In this way, the ball bearings 22, or the interlock 21, may be configured to be self-adjusting per se in order to hold without play the counter-bearing that is formed. The pinion 15 and the interlock 21 are supported on a plate 23, which can be tilted by a tilting bearing and ensures that axes 24 of the pinion 15 and of the ball bearings 22 remain aligned relative to one another. Because of the geometrical arrangement of the pinion 15 and of the interlock 21, the plate 23 follows the frame 17 exactly, regardless of the angular location which the control element 13 occupies.

[0028] Magnetic strips 30, which cooperate with magnetic sensors 31 that are firmly connected to the housing 18 of the control element 13 and together form angle sensors 32, are arranged on the tilting bearing 14 and on the plate 23. As an alternative, optical sensors may also be used. In this case, the magnetic strips 30 are alternately poled so that, when the control element 13 is tilted, the magnetic sensors 31 supply an AC voltage signal from which the current angular location can be determined by counting the zero crossings. In order to be able to establish the direction of rotation as well, the magnetic strips 30 and/or the magnetic sensors 31 are duplicated, so that the direction of rotation can also be determined with the aid of the phase angle of the zero crossing. Hall sensors are preferably used as magnetic sensors 31.

[0029] The signals of the magnetic sensors 31 are delivered via signal paths 43 to an evaluation unit 40, which is likewise located inside the housing 18 of the control element 13 and can be seen in FIG. 2. The evaluation unit 40 is connected via a signal path 41 to the actuator 19 in order to drive it. Furthermore, the evaluation unit 40 is actively connected to the edge sensor 52, which generates the required location information of the running material web 3, via a further signal path 42.

[0030] The evaluation unit 40 will be explained in more detail with the aid of the outline circuit diagram according to FIG. 4. The edge location signal of the edge sensor 52 is delivered via the signal path 42 to a regulator 50, preferably with PID behaviour. At its output 53, the regulator 50 supplies a correction signal by which the actuator 19 is driven and the cheek 12 is therefore set.

[0031] Provided between the regulator 50 and the actuator 19, purely for the purpose of increasing the operational reliability, is an adder 54 which can subtract a constant but adjustable value from the output signal of the regulator 50. In general, that is to say in normal operating states, the adder 54 receives a zero signal at its non-inverting input 55 so that the entire adder 54 is inactive in this operating state and the signal at the output 53 of the regulator 50 is forwarded unchanged via the signal path 41 to the actuator 19.

[0032] The magnetic sensors 31 are actively connected via signal amplifiers 60 to a phase detector 61. This phase detector 61 records zero crossings at its inputs 62, including the phase angle of these zero crossings. Depending on which of the two inputs 62 the zero crossing with a positive flank occurs at first, a clock signal is output either on its plus output 63 or on its minus output 64. This indicates that the magnetic sensors 31 have moved forwards by one polarity period either in the plus direction or in the minus direction. In this way, the rotation angle on the one hand of the tilting bearing 14 and on the other hand of the tiltable plate 23 is recorded with a high accuracy. In order to be able to determine the actual rotation angle, the plus output 63 and the minus output 64 are connected to a bidirectional counter 65. This bidirectional counter 65 counts only the flanks of the plus output 63 upwards and of the minus output 64 downwards, so that its counter state is proportional to the angle actually present.

[0033] The described circuit parts of the magnetic sensors 31 up to the bidirectional counter 65 are duplicated in order to record on the one hand the rotation angle of the tilting bearing 14 and on the other hand the rotation angle of the tiltable plate 23. They are in principle constructed identically and will therefore not additionally be described in detail. The outputs of the two bidirectional counters are delivered to an adder 66, which records the difference of the two counter states and forms calculation means 66′. This differential angle corresponds to the actual cheek angle to within an additive correction value, which is not important in what follows. It is in principle also conceivable to omit the adder 66 by replacing the two bidirectional counters 65 with a single bidirectional counter 65, which then has two upward counting inputs and two downward counting inputs that are connected to the corresponding phase detectors 61. It has been found that although this measure saves on resources, it entails the risk of counting pulses being lost. This is, in particular, because the counting pulses occur entirely asynchronously and may therefore even occur virtually simultaneously. This leads to undefined states in the counter circuit, which then causes counting pulse losses. Since this is a safety-relevant component which is intended to record the respective angular location of the control element 13 exactly at any instant, this simplification is generally not acceptable.

[0034] An output 67 of the adder 66 is compared by means of a comparator 68, 69, 70 with threshold values of threshold value generators 71, 72, 73. The threshold value generators 71, 72, 73 may in the simplest case be potentiometers which output analogue voltages. As the threshold value generators 71, 72, 73, it is however also conceivable to provide a numerical keypad or a communication link via which the data entry to the threshold value generators 71, 72, 73 is made possible by means of a terminal (not represented). In this case, the comparison is carried out insofar as an active signal is output when the value at the output 67 is greater than the respective threshold value. In this way, critical operating states of the cheek 12 are established.

[0035] If the value at the output 67 is not greater than each of the threshold values of the threshold value generators 71, 72, 73, the operating state is a normal operating state so that the regulation by means of the regulator 50 can operate by any desired setting of the cheek 12. In this operating state, a zero value is delivered to the adder 54 so that the signal of the regulator at its output 53 is delivered unchanged to the actuator 19 via the signal path 41.

[0036] If the signal at the output 67 exceeds the threshold value of the threshold value generator 71, the comparator 68 transmits a signal to the regulator 50, by which the output value of the regulator 50 is kept. If regulation deviations which travel via the signal path 42 to the regulator 50 subsequently occur, the latter will no longer react to these regulation deviations and also the cheek 12 will therefore not be set further by means of the actuator 19. This effect then takes place in such a way that although the regulator 50 can set the cheek 12 in the direction of its neutral position lying parallel to the web running direction 2, it cannot do so in the opposite direction. This avoids the cheek 12, the material web 3 or the subsequent tenter machine from being damaged by excessive tilting of the cheek 12. If the fault which has triggered this exceptional situation is intended to be eliminated by itself, the regulator 50 will reduce its signal at the output 53 so that the limiting action of the comparator 68 is removed. The evaluation unit 40 therefore returns automatically into the normal operating state with self-eliminating faults.

[0037] It may occur that the cheeks are tilted further despite the aforementioned limitation, so that the operating state of the entire device 1 may become critical. This occurs particularly if a width setting of the tenter machine is carried out and the limiting effect of the comparator 68 is thereby removed.

[0038] For this purpose, the second comparator 69 is provided, which compares the signal at the output 67 with a somewhat higher threshold value. At its output 75, this comparator 69 outputs a signal which is zero in the normal but inactive state, although when the threshold value of the threshold value generator 72 is exceeded it supplies a value predeterminable by a generator 56 to the adder 54. In this way, the output signal of the regulator 50 is reduced by this predetermined value so that the cheek 12 is forced to be tilted back by this value in the direction of the neutral setting. The generator 56 may be produced in a similar way to the threshold value generators 71, 72, 73 or else differently.

[0039] In this way, the situation is alleviated after the cheek 12 has been forced to be tilted back in the direction of the neutral location under the effect of the comparator 69.

[0040] If the measures—due to the comparator 69—do not also show the required effect, it may be assumed that there is a particularly serious fault which makes it impossible to operate the equipment as a whole. For this purpose, the signal at the output 67 of the adder 66 is compared with a third threshold value in the comparator 70, which, if this threshold value is exceeded, then transmits a highly prioritised signal via the output 75 to the subsequent tenter machine so that the latter is turned off. This state may be removed only by means of the reset 74.

[0041] Preferably, the evaluation unit 40 as a whole or parts thereof are produced in the form of a microcontroller. This simplifies the structure of the evaluation unit 40. FIG. 4 represents signal paths which are to be configured in a multi-bit fashion with an increased line thickness.

[0042] Since some of the embodiments of this invention are not shown or described, it should be understood that a great number of changes and modifications of these embodiments is conceivable without departing from the rationale and scope of protection of the invention as defined by the claims.