This application claims priority from German Patent Application No. 10 2005 033 180.7 dated Jul. 13, 2005, the entire disclosure of which is incorporated herein by reference.
The invention relates to an apparatus for detecting a parameter at a plurality of slivers fed to a drafting system of a spinning machine, especially for detecting the movement and/or the presence of a sliver.
In a known form of apparatus, the parameter is measurable separately at each sliver, each sliver being drawn out of sliver cans over a respective driven supply roller and fed to the drafting system and being mechanically sensed by a feeler element, the deflections of which are convertible into electrical signals and which feeler element has a sensor element associated with it.
In the case of an apparatus described in WO 98/18985 A, guide rollers as well as eight measuring elements and eight cans for eight slivers are provided—looking upstream from a drafting system. Leads connect all measuring elements in parallel to a computer. The measuring elements each comprise a driven roller and a follower roll, which is mounted on a lever displaceable about an axis of rotation. The roller has a groove for the sliver, which groove can also be engaged by the roll for sensing the sliver. Each sliver entering the drawing system is sensed beforehand in a measuring element to detect a parameter. Possible parameters are preferably the weight, the thickness, the mass etc, in the form of absolute values or relative values, such as the changes in weight, thickness or mass. In this process, the roll is deflected by the volume occupied by the sliver on the roller, which is converted to an output signal proportional to this deflection. The output signals of all measuring elements are fed to the computer via the leads. Each measured value can be compared with a threshold value to ensure that a sliver is actually present, or that the sliver has reached a minimum volume. This dynamics of this mechanical feeling system of tongue and groove roller are not satisfactory at high delivery speeds. The feeler roller may be caused to oscillate owing to the large mass.
It is an aim of the invention to produce an apparatus of the kind described in the introduction that avoids or mitigates the said disadvantages, in particular is of simple structure and allows an improved and more accurate detection of the individual slivers.
The invention provides an apparatus for detecting a parameter relating to a plurality of fibre slivers that are being fed to a drafting system of a spinning machine comprising
The contactless distance sensor (sensor measuring distance) according to the invention allows an improved and more accurate detection of the individual slivers in a structurally simple manner. In a preferred arrangement, the feeler element is a pressure roll that cooperates with a feed roller. Advantageously, the measuring point of the optical distance sensor is located on the pressure roll arm, which is, for example, movably mounted. On initial start up (machine at standstill) the pressure roll is placed on the feed roller with no sliver, the distance to the pressure roll is measured and stored in a control unit. With the machine at a standstill the sliver is then placed between the pressure roll and feed roller. The thickness of the sliver reduces the distance between the distance sensor and pressure roll, and the control unit detects a constantly present signal. This signal is compared with the value at initial start up, and it is established that a stationary sliver is present. This measurement with a sliver present ought always to be effected automatically before the machine is switched on, in order to ensure that a sliver is present or that an exchanged sliver is recognised. Due to the transport of the sliver (machine running), the pressure roll is now caused to oscillate permanently, the distance alteration resulting therefrom is detected, a continuously modifiable signal is measured and the control unit detects that a moving sliver is present. If a sliver tears, the pressure roll runs without a sliver on the feed roller, the measured signal is compared with the signal at start up, the measured value at start up is detected and by combining it with the function “machine running”, the control unit recognizes that the machine is running with no sliver present. In all the described states in which, by combining signals, the control unit detects that the machine is “not ready for operation”, the machine goes to malfunction and switches off. By measuring these different signals, which are evaluated in combination with the function of the machine by programming techniques, it is possible to achieve efficient monitoring of individual slivers at a roller inlet on the basis of the accurate indirect optical/ultrasound distance measurement. The respective individual values of the sliver calibrations can be further processed by programming (e.g. using statistics, alterable measurement parameters of the sliver monitoring etc.).
Advantageously, the distance sensor is a sensor that measures distance using waves or rays. The distance sensor may be an optical or acoustic distance-measuring sensor. The sensor may be an ultrasound distance sensor (distance-measuring sensor). Advantageously, the light ray or sound ray is focussed. The distance sensor may be a light scanner. Preferably, the distance sensor comprises a transmitter and a receiver. The distance sensor may be a laser scanner. The distance sensor may use visible light or may use infrared light. The distance sensor may determine the distances to the feeler element. The distance sensor may determine the distance to a counter-element associated with the feeler element. In one embodiment, the distance sensor is fixed and the counter-element is movable relative to the distance sensor. In another embodiment, the distance sensor is movable and the counter-element is fixed relative to the distance sensor. The counter-element may have a flat scanning surface. The counter-element may have a smooth scanning surface. The counter-element may have a curved scanning surface. The scanning surface is advantageously reflective. Advantageously, the evaluating unit is connected to an electronic open-loop and closed-loop control device. The distance sensor may be an analog sensor. Where appropriate, the signals are advantageously conducted from the measuring point to the evaluating unit using an optical waveguide. Advantageously, the distance sensor scans the excursions of a movable feeler tongue. Advantageously, the distance sensor scans the excursions of a movable feeler roller. Advantageously, the distance sensor scans the excursions of the feeler tongue or the feeler roller directly or indirectly. The apparatus may be used for ascertaining and displaying sliver breakage. Advantageously, the feeler element is mounted on a fixed pivot bearing. The apparatus may be used to determine the parameters of an elongate, substantially untwisted fibre bundle. The distance sensor may be used to measure the parameters with a continuously moving fibre bundle. Advantageously, the determined values for the sliver mass are used to adjust sliver mass fluctuations of the fibre bundle by controlling at least one drafting element of a spinning preparation machine in which the fibre bundle is being drawn. The apparatus may be used for ascertaining and displaying movement. Advantageously, the feeler element is a pivotally mounted lever. Advantageously, the feeler element co-operates with a force-applying element, for example, a counter-weight, spring or the like. Advantageously, the feeler element is mounted so as to be movable in the horizontal direction. Advantageously, the feeler element is resiliently mounted at one end. Advantageously, the feeler element is mounted on a holding member, for example, a lever. Advantageously, the feeler element is mounted so as to be pivotable about a vertical axis. Preferably, the bias of the movably mounted feeler element is effected by mechanical, electrical, hydraulic or pneumatic means, for example, springs, weights, natural resilience, loading cylinders, magnets or the like, and can be adjustable. Advantageously, there is a plurality of distance sensors, each of which scans the thickness of a sliver with a feeler element (individual sliver scanning). Advantageously, the slivers are drawn out of spinning cans over a plurality of driven feed rollers at an input part and are conveyed to a driven drafting system. Advantageously, the feed rollers are fixed. Advantageously, a movable (deflectable) co-rotating roller lies on each feed roller. Advantageously, the movable roller is mounted on rotary bearings by way of rotary levers. Advantageously, the distance sensors are able to detect the deflections of the movable roller and/or at least one rotary lever. Advantageously, the feeler element with the distance sensors is provided at the output of the cans. Advantageously, the feeler elements with the distance sensors form part of an arrangement for removing sliver from the can. Advantageously, the co-rotating roller (pressure point) lies under its own weight on the feed roller. Advantageously, the evaluating device comprises a multi-channel evaluating device. Advantageously, each distance sensor is arranged to be switched off individually. Advantageously, there is a roller nip between the two cylindrical peripheral surfaces of the feed roller and the co-rotating roller (pressure roll). Advantageously, when conveying the fibre bundle the pressure roll oscillates permanently.
The invention also provides an apparatus for detecting a parameter at a plurality of slivers fed to a drafting system of a spinning machine, especially for detecting the movement and/or the presence of a sliver, in which the parameter is measurable separately at each sliver, each sliver being drawn out of sliver cans over a respective driven supply roller and fed to the drafting system and being mechanically sensed by a feeler element, the deflections of which are convertible into electrical signals and which feeler element has a sensor element associated with it, wherein a contactless distance sensor (distance-measuring sensor) is provided to detect the position of each feeler element, which sensor is connected to an electrical evaluating unit.
a is a schematic side view of a feed table of a draw frame with an apparatus according to the invention;
b is a plan view of the apparatus of
a is a plan view of a diverting arrangement for diversion of a sliver by a sliver guide between a feed roller and a top roller with a light scanner;
b is a side view of the arrangement of
a is a side view of a feed table of a draw frame with three pairs of feed and top rollers, a respective light scanner being associated with weighting levers; and
b is a schematic side view of a draw frame with a block diagram of an electronic open-loop and closed-loop control device for the draw frame.
The side view according to
As shown in
b illustrates the rollers 8a to 8f, 12a, 12b, 15, III, II and I, all arranged underneath. According to
Referring to
According to
According to
The leads 17a, 17b, 17c can be in the form of fibre optic cables. A signal converter (not shown) that converts the light pulses into electrical pulses then has to be arranged between the light scanners 19 and the open-loop and closed-loop control device 38.
According to
The drawn slivers 7 reach a web guide 27 at the drafting system outlet 22 and are drawn by means of the delivery rollers 28, 29 through a sliver funnel 30, in which they are condensed to a sliver 7I, which is subsequently laid in the can 42. The take-off rollers 15, 16, the bottom feed roller III and the middle bottom roller II, which are mechanically coupled via toothed belts, are driven by the variable speed motor 31, wherein a desired value can be preset. (The associated top rollers 26 and 25 co-rotate). The bottom delivery roller I and the delivery rollers 28, 29 are driven by the main motor 32. The variable speed motor 31 and the main motor 32 each have their own closed loop system, 33, 34, respectively. The control (speed control) is elected by a closed-control loop, a tachogenerator 35 being associated with the variable speed motor, and a tachogenerator 36 being associated with the main motor 32. At the outlet 22 to the drafting system, a variable proportional to the mass, for example, the cross-section of the emerging sliver 71, is obtained from a delivery measuring element 37 associated with the sliver funnel 30. A central processing unit 38 (open-loop and closed-loop control device), for example, a microcomputer with microprocessor, relays a setting of the desired variable for the variable speed motor 31 to the controller 33. The measured variables of the measurement element 14 are relayed to the central processing unit during the drafting operation. The manipulated value for the variable speed motor 31 is determined in the central processing unit 38 from the measured variables of the measurement element 14 and from the desired value for the cross-section of the emerging sliver 7′. The measured variables of the delivery measurement element 37 serve to monitor the emerging sliver 7′ (output sliver monitoring). Using this control system, fluctuations in the cross-section of the slivers 7 fed in can be compensated by corresponding regulations of the preliminary drafting process and the sliver 7I can be evened out. The reference number 39 denotes an input device and the reference number 40 denotes a display means, for example a visual display unit or similar. 17a, 17b, 17c denote the leads that connect the light scanners 20a, 20b, 20c respectively to the processing unit 38 (evaluating unit), as shown in
b has been described using the example of an autoleveller. A non-regulated draw frame is also included.
The sliver 7 (a maximum of 8) is drawn out of the can 5 over the feed creel 6 through the draw frame attached thereto. The roller creel principally comprises two supports and a beam. Feed rollers are mounted on this beam by means of stay bars 18 and pressure rolls 9. The feed rollers 8 are driven by the draw frame. A sliver guide 43 and a stay bar 18 with pressure roll 9 are mounted at the feed rollers. To stabilise it, the sliver 7 is first guided through the sliver guide 43 and then over the driven feed roller 8 towards the draw frame. The sliver 7 can only be transported by the feed roller 8 when the pressure roll 9, which is connected to the stay bar 18 via a movable arm 19, lies on the sliver 7 and, by virtue of its relatively large dead weight, presses the sliver 7 onto the feed roller 8. The sliver 7 is thus pressed to a certain degree between the feed roller 8 and the pressure roll 9. So that the sliver 7 can be moved without sustaining damage, the pressure roll 9 is rotatably mounted.
By mounting a distance sensor, for example, an optical distance sensor 20 (optionally with fibre optic cable), on the stay bar 18 that is present with pressure roll 9, it is possible to carry out a distance measurement to the pressure roll 9 and to detect consequential states of the sliver. The advantage is that a completely mechanically dissociated, contactless individual monitoring of the individual slivers takes place. The operating states described below arise from the program linkage between distance measurement and operating state of the machine.
The optical distance sensor 20 has its measuring point on the arm 19 of the pressure roll 9, this arm being, for example, movably mounted. At initial commissioning (machine at standstill), the pressure roll 9 is placed on the feed roller 8 with no sliver 7, the distance to the pressure roll 9 is measured and stored in a control unit 38. With the machine at a standstill the sliver 7 can then be placed between the pressure roll 9 and feed roller 8. The thickness of the sliver 7 reduces the distance between the distance sensor 20 and pressure roll 9, and the control unit 38 detects a constantly present signal; this signal is compared with the value at initial start up, and a stationary existing sliver 7 is detected. This measurement with a sliver 7 present ought always to be effected automatically before the machine is switched on, in order to ensure that a sliver 7 is present or that an exchanged sliver 7 has been recognised. Owing to the transport of the sliver 7 (machine running), the pressure roll 9 is now caused to oscillate permanently, the variation in distance resulting therefrom is detected, a continuously alterable signal is measured and the control unit 38 detects that a sliver 7 is present and is moving. If the sliver 7 tears, the pressure roll 9 runs without a sliver 7 on the feed roller, the measured signal is compared with the signal at start up, the measured value at start up is detected and by combining it with the function “machine running”, the control unit 38 recognizes that the machine is running with no sliver present. In all the described states in which, by combining signals, the control unit 38 detects that the machine is “not ready for operation”, the machine goes to malfunction and switches off. By measuring these different signals, which are evaluated in combination with the function of the machine by programming techniques, it is possible to achieve efficient monitoring of individual slivers at a roller inlet on the basis of the accurate
indirect optical distance measurement. The respective individual values of the sliver calibrations can be further processed by programming (e.g. using statistics, alterable measurement parameters of the sliver monitoring etc.). An 8-channel evaluating unit may advantageously be used. Furthermore, it is an advantage to be able to switch off individual sliver monitoring by control engineering methods
Although the foregoing invention has been described in detail by way of illustration and example for purposes of understanding, it will be obvious that changes and modifications may be practised within the scope of the appended claims.
Number | Date | Country | Kind |
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10 2005 033 180.7 | Jul 2005 | DE | national |