CROSS REFERENCE TO RELATED APPLICATION
This application claims priority from German Patent Application No. 10 2005 020 506.2, dated Apr. 29, 2005, the entire disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The invention relates to an apparatus on a drafting system of a spinning machine, especially a draw frame, carding machine, combing machine or the like, for weighting the drafting system rollers, having at least one pressure fluid cylinder with a piston which is acted upon by pressure fluid and is arranged so as to be axially movable inside a cylinder housing and from which a piston rod extends.
In a known apparatus (EP 1 428 914 A), a switching disc is frictionally mounted coaxially with the piston so as to be displaceable on the piston rod, which switching disc cooperates with a switch to determine the position of the piston. The switching disc is at least partly permanently magnetic in order to cooperate with an inductive sensor as a switch for determining the position of the piston. If a winding (lap) of fibre material then forms around the upper roller, the floating upper roller is pressed in the direction of the pressure fluid cylinder.
The presser rod of the pressure fluid cylinder making contact with the upper roller consequently moves in the direction of its retracted end position. When the presser rod is retracted, the switching disc, which is frictionally mounted thereon, closes the switch and the drafting system is switched off. The drafting system can then be opened manually and the lap removed. The drafting system can then be brought into the operating position again by closing the weighting arm.
It is an aim of the invention to provide an improved apparatus on a drafting system for determining the position of the piston with the piston rod.
SUMMARY OF THE INVENTION
The invention provides an apparatus on a drafting system of a spinning machine for weighting a drafting system roller, comprising:
- a cylinder;
- a piston axially movable within the cylinder;
- a piston rod extending from the piston for applying weighting to the roller;
- a sensor; and
- an evaluation device;
wherein the sensor is an optical sensor arranged to determine a distance between the sensor and a counter-element and the sensor is connected to the evaluation device for determining the position of the piston and piston rod.
The apparatus according to the invention makes it possible to use control technology to monitor the movement of the piston, including the platform, in both directions, up and down, for example by means of optical sensor heads of a distance sensor. As a result of the travel of the pistons in both directions, the distance between the platform and the optical sensor changes, which consequently in turn transmits a changed output signal to the control means. By virtue of the changed output signal, the control means is able to identify the movement of the piston in both directions. Furthermore, the control means is able to ascertain by means of the signals the path travelled by the piston. By means of that exact measurement and by means of the maximum value for the upward excursion of the upper roller caused by lap formation, which value is stored in the control means, the fault “lap formation” can be precisely identified. The value of the upward excursion up until a fault message is given can accordingly be made freely programmable and can be changed as required. A further advantage of such distance measurement is that precise identification of both lap formation and wear to the upper rollers can be effected automatically by the control means using an optical sensor. The upper rollers of the drafting system are routinely provided with a resilient covering, for example of rubber or the like. In one preferred arrangement, when the machine is first started up with new upper rollers, the drafting system is closed and acted upon by compressed air. The optical sensor ascertains the distance between the sensor and the platform of the piston and stores that value in the control means. The value ascertained is used to calculate the roller diameter of a new upper roller, from which there is obtained, after subtraction of the maximum wear value (stored in the control means as a fixed or variable parameter), a minimum roller diameter. The minimum roller diameter is likewise stored. As a result of the wear and abrasion to the upper rollers, that distance becomes increasing larger. By always calibrating the sensor each time the drafting system is closed, the distance with respect to the platform is ascertained afresh each time. The newly ascertained value forms the current diameter of the upper roller. The control means compares the currently ascertained diameter with the fixed programmed parameter for the wear i.e. the stored value for the minimum upper roller diameter. When the minimum roller diameter of the upper roller is reached, the machine switches to fault mode and switches off. The upper rollers must be replaced by new rollers. The machine can be started up again only when distance measurement indicates a roller diameter greater than the pre-set minimum roller diameter has been reached. Optical distance measurement inside the presser arms in accordance with the invention can achieve a wear-free and tolerance-independent measurement in both directions of the pistons that is absolutely precise; also automatic monitoring of lap formation and of wear to the upper rollers. If necessary, all stored values relating to lap formation and the wear behaviour of the upper rollers can be retrieved from the control means for statistical purposes. The machine cannot be started up with worn upper rollers. As a result, material wastage caused by worn upper rollers is not possible.
In one embodiment, the distance sensor is in fixed position and the counter-element is movable relative to the distance sensor, for example, the counter-element is, or is a part of, the piston. In another embodiment, the distance sensor is movable and the counter-element is in fixed position relative to the distance sensor. If desired, the apparatus can be used for lap display. As well or instead the apparatus can be used for displaying wear to the rollers.
In one advantageous embodiment, the counter-element has a flat scanning surface. Preferably, the scanning surface is able to reflect light beams. Advantageously, the distance sensor is a light sensor. Advantageously, the distance sensor has a transmitter and a receiver. The distance sensor may be a laser sensor. The distance sensor may use visible light. The distance sensor may use infra-red light. Advantageously, the distance sensor for location determination is mounted at an angle of 90° to the horizontal base surface of the counter-element. Advantageously, the distance sensor and the counter-element are arranged in a closed housing. Advantageously, the distance sensor is connected to an electrical evaluation device. Advantageously, the evaluation device is connected to an electronic control and regulation device. The distance sensor may be an analog sensor. In one embodiment, an optical distance sensor may scan the distances with respect to a sloping surface of the counter element.
Advantageously, the drafting system comprises three upper rollers with three presser arms. Advantageously, the drafting system comprises four upper rollers with four presser arms. Advantageously, the sensor is able to detect the movements of the piston in two directions. Advantageously, the electronic control and regulation device is able to ascertain the path changes of the piston. Advantageously, the maximum value for the excursion of the upper roller caused by lap formation is storable in the control and regulation device. Advantageously, the value of the excursion up until a fault message is given is freely programmable. Advantageously, the sensor is calibratable on each operation of closing the drafting system. Advantageously, the electronic control and regulation device comprises a 4-channel evaluation device. Advantageously, measured values relating to lap formation and/or to the wear behaviour of the upper rollers are storable.
The invention also provides an apparatus on a drafting system of a spinning machine, especially a draw frame, carding machine, combing machine or the like, for weighting the drafting system rollers, having at least one pressure fluid cylinder with a piston which is acted upon by pressure fluid and is arranged so as to be axially movable inside a cylinder housing and from which a piston rod extends, the piston rod passing through at least one cylinder cover that forms the end boundary of the cylinder housing, there being a sensor arrangement for determining the position of the piston with the piston rod, wherein for determining the position of the piston with the piston rod an optical distance sensor scans the distances with respect to a surface of a counter-element and the distance sensor is connected to an electrical evaluation device.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic side view of the drafting system of a draw frame having an apparatus according to the invention;
FIG. 2 shows a portion of FIG. 1 in section corresponding to K-K (FIG. 1) with a pneumatic upper roller weighting device;
FIG. 3 is a front view of a presser arm having an integral housing and two presser rods;
FIG. 3
a is a perspective view of the presser arm according to FIG. 3;
FIG. 4 shows an embodiment in which a distance sensor is arranged in the cylinder base relative to the piston;
FIG. 5 shows the distance sensor with transmitter and receiver;
FIG. 6 shows an embodiment in which a distance sensor is arranged in the piston relative to the cylinder base;
FIG. 7 shows an embodiment in which a distance sensor is arranged in the cylinder cover relative to the piston;
FIG. 8 shows an embodiment in which a distance sensor is arranged in the cylinder housing relative to a ramp-shaped counter-element; and
FIG. 9 is a diagrammatic block circuit diagram of an electronic control and regulation device (evaluation device) having a distance sensor, memory element, 4-channel evaluation means and display device.
DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS
With reference to FIG. 1, a drafting system S of a draw frame, for example a draw frame known as a TC 03 (Trade Mark) made by Trützschler GmbH & Co. KG of Mönchengladbach, Germany. The drafting system S is configured as a 4 over 3 drafting system, that is to say it consists of three lower rollers I, II, III (I output lower roller, II middle lower roller, III input lower roller) and four upper rollers 1, 2, 3, 4. In the drafting system S, the drafting of the fibre bundle 5, which consists of a plurality of slivers, is carried out. The drafting operation is composed of the preliminary drafting operation and the main drafting operation. The roller pairs 4/III and 3/II form the preliminary drafting zone and the roller pairs 3/II and 1,2/I form the main drafting zone. The output lower roller I is driven by the main motor (not shown) and thus determines the delivery speed. The input and middle lower rollers III and II are driven by a regulating motor (not shown). The upper rollers 1 to 4 are pressed against the lower rollers I, II, III by presser elements 91 to 94 (weighting device) in presser arms 11a to 11d which are pivotable about pivot bearings (see FIG. 3) and are thus driven by way of frictional engagement. The direction of rotation of the rollers I, II, III; 1, 2, 3, 4 is indicated by curved arrows. The fibre bundle 5, which consists of a plurality of slivers, runs in direction A. The lower rollers I, II, III are mounted in stands 14 (see FIG. 3) which are arranged on the machinery frame 15. Reference numeral 29 denotes a compressed air supply.
According to FIG. 2, a pneumatic cylinder 9, as one of the presser elements, is associated at the top with a support element 12a and at the bottom with a holding element 13a. The pneumatic cylinder 9 forms a cylinder unit with a cylinder cavity 17 having two portions 17a and 17b in which a piston 18a is guided by means of a presser rod 19a in a sliding bush 20. The roller journal 4a of the upper roller 4, passing through an opening in a holding bracket 27, engages in a bearing 27. The bearing 22a accommodating the upper roller 4 extends into a chamber between the presser rod 19 and the roller journal IIIa of the lower roller III. The bearing 22a is mounted by means of a shoulder 26 on the holding element 13a. A membrane 16 divides the cylinder cavity 17 in terms of pressure. In order that pressure is generated in the upper portion 17a of the cylinder cavity 17, the latter can be supplied with compressed air p1 by means of a compressed air connection 23. The lower portion 17b of the cylinder cavity 17 is vented by means of a venting bore 24. The upper portion of the cylinder cavity 17 can be vented and the lower portion of the cylinder cavity 17 can be supplied with compressed air in corresponding manner. In operation, after a fibre bundle 5 has been guided over the lower rollers I, II, III, the presser arms 11 are pivoted into the operating position shown in FIG. 3 and fixed in that position by a fastening device (not shown), so that the presser rollers 1, 2, 3, 4 are able to exert pressure. Such a pressing action is produced on the one hand by the fact that the presser rods 19 each rest on the corresponding bearing 22 and on the other hand because an overpressure has been generated in the cavity above the membrane 16. As a result, the presser rod 19 presses with its other end on the bearing 22 in order to create the mentioned pressing action between the upper roller 4 and the lower roller (drive roller) III. The presser rod 19 (piston rod) is displaceable in the direction of arrows D, E.
According to FIG. 3, 3a, the upper roller 4 is associated with the portal-shaped presser arm 11a. (The upper rollers 2 to 4 are associated with a corresponding presser arm 11—not shown). The presser arm 11a is in the form of a housing 30 of glass-fibre-reinforced plastics and is produced by injection-moulding. The housing 30 is an integral component which is of unitary construction and comprises the support element 12, the two bodies of the pressure elements 9a1 and 9a2 (pressure cylinders), two intermediate elements 31a and 31b and two holding elements 13a and 13b. The support element 12a is in the form of a channel 33 of approximately U-shaped cross-section that is open on one side, in the interior of which pneumatic lines 34 and electrical leads 35 are arranged. The open side of the channel 33 is closable by a removable cover 36 which consists of glass-fibre-reinforced plastics, is approximately U-shaped in cross-section and is resilient so that it is attached to the channel 33 by a press-fit connection. The housing 30 is preferably formed in one piece. The integral housing 30, which combines all essential functional elements for holding and weighting the respective upper rollers 1 to 4, is in this way economical to produce. At the same time, the entire presser arm 11a to 11d is in simple manner pivotable about the pivot bearing 10 and can be locked and unlocked by a locking device (not shown). The presser rods 19a and 19b are relieved of load and thus raised from the bearings 22a and 22b of the upper roller 4.
In the embodiment of FIG. 4, the compressed-air-operated pressure fluid cylinder consists of a cylinder housing 6 in which a piston 18 is arranged so as to be axially movable. A piston rod 19 (presser rod) extends from the piston 18. The piston rod 19 emerges from a cover-side opening 7 of the pot-shaped cylinder housing 6. The opening 7 and the inner wall of the cylinder housing 6 serve for guiding the piston 18 with the piston rod 19. The piston rod 19 cooperates—in the manner described at the beginning—with an upper roller 4 of a drafting system for fibre material. The upper roller 4 consists of a metal cylinder 41, to which a roller covering 42 (hollow cylindrical in cross-section) made of an elastomer is attached. The pot-shaped cylinder housing 6 is closed with respect to the end face remote from the opening 7 by a cylinder base 8. In this embodiment, the connection between the cylinder housing 6 and the cylinder base 8 is in the form of a clip connection. The cylinder base 8 has a pressure fluid connection 25 for acting upon a pressure chamber 32 of the pressure fluid cylinder. Furthermore, in the region of the pressure chamber 32, a guide recess 33 is provided in the cylinder base 8. The guide recess 33 corresponds with a cylindrical extension 37 which is screwed into the piston rod 19 coaxially therewith to form a lengthwise extension thereof. The corresponding screw connection 38 serves simultaneously also for attaching the piston 18 to the piston rod 19. A compression spring 39 is arranged between the piston 18 and the cover 6a of the cylinder housing 6. Using the spring-returnable piston 18, in the non-pressurised state the piston 18 is always returned to the end position by mechanical means.
The cylinder base 8 is provided for accommodating a distance sensor 40. The distance meter 40 is arranged in a recess 43 (see FIG. 5), which is open on one side, in the cylinder base 8 in order to detect the position of the piston 18. The beam path 40′ of the distance sensor 40 passes through the pressure chamber 32 which is located on the side of the piston 18 remote from the opening 7 for the piston rod 19. Furthermore, on the cylinder housing 6 there is formed a radially inwardly directed annular shoulder 41 which acts as upper end-stop for the piston 18. Reference numeral 42 denotes a circumferential, approximately ring-shaped elastomeric seal between the piston 18 and the inner wall of the cylinder housing 6.
According to FIG. 5, the optical distance sensor 40 is arranged in fixed position in a recess 43, which is open on one side, in the cylinder base 8. The distance sensor 40 (light sensor) consists of a light transmitter 40a and a light receiver 40b. The light beam 40′ emitted by the light transmitter 40b is reflected by the smooth surface 18′ of the piston 18 and the reflected light beam 40″ is received by the light receiver 40b. By virtue of its arrangement inside the pressure chamber 32, the distance sensor 40 is protected from dust. Reference numeral 35 denotes an electrical lead.
In the embodiment of FIG. 6, a distance sensor 401 is arranged in a recess, which is open on one side, in the piston 18, the light beam scanning the fixed counter-surface 8′ of the cylinder base 8.
In the embodiment of FIG. 7, a distance sensor 402 is arranged in fixed position in a recess in the cover 6a, the light beam scanning the counter-surface 18″ of the piston 18.
In the arrangement of FIG. 8, a distance meter 403 is arranged in fixed position in a recess, which is open on one side, in the cylinder housing 6, the light beam scanning a ramp-shaped counter-element 44 mounted on the extension 37. The light scanner 403 thus scans a movable sloping surface. At a given distance between the distance sensor 403 and the base surface of the counter-element 44 and at a predetermined angle of inclination (a) between the base surface and the sloping surface, the evaluating device 45 (see FIG. 9) calculates the location of the piston 18 on the basis of the distance between the distance sensor 403 and the sloping surface of the counter-element 44.
In accordance with FIG. 9, the optical distance meter 40 is connected to an electronic control and regulation device 45, for example a microcomputer having a microprocessor. Furthermore, the control and regulation device 45 is connected to a memory element 46 which is able to store the measured values of the distance sensor 40 and predetermined desired values, for example maximum and minimum values. In addition, a 4-channel evaluation device 47 and a display device 48 (lap and/or wear message) are connected to the control and regulation device 45.
Using the apparatus according to the invention, by means of the contact pressure of the piston rod 19 on the roller covering 42 of the upper roller 4 and accordingly the determination of the position of the piston 18, it is possible for both lap and wear to be indicated.
Whilst the invention is described in detail above with reference to a drafting system of a draw frame, it may be applied instead, with appropriate modification, to the drafting systems of other spinning machines, in particular, of carding machines or of combing machines.
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.
Patent Application
20060242798
