Patent Application
20080256983
The invention relates to a control device for at least one thread feeding device of a thread processing machine, especially a knitting machine. The invention also relates to a method for positive thread feeding to a textile machine, especially a knitting machine with changing thread requirements.
Circular knitting machines and flat knitting machines are known, which are designed for stitching patterned goods. With respect to patterned goods, different stitching positions must be supplied with thread intermittently rather than continuously.
One example of a circular knitting machine for creating patterned goods is seen in EP 0 724 033 A1. The circular knitting machine has a cutting device in order to cut away unnecessary thread. If thread of the corresponding color is needed again, the previously cut thread is fed again to the stitching position.
In addition, a so-called striping attachment for a circular knitting machine and for a circular machine is seen in DE-PS 2024 341. The striping attachment contains devices to lay threads in and out, i.e., to feed the stitching positions selectively.
Knitting machines that stitch plain-weave goods, i.e., to whose stitching positions continuous thread is fed, are usually supplied with thread by means of so-called positive feed wheel mechanisms, which feed a certain amount of thread to the stitching position for every rotation of the machine cylinder. Thus, the mesh size is uniform independent of tolerances of the stitching positions. Such positive feed wheel mechanisms are usually driven by means of a toothed belt or the like and thus are forced to run in sync with the knitting machine.
Knitting machines used to create patterned goods cannot be supplied with thread with such positive feed wheel mechanisms. Instead, so-called friction feed wheel mechanisms are usually used, as seen in DE 100 06 599 A1. Such friction feed wheel mechanisms have a thread feed wheel that is driven so that it rotates. The thread contacts this thread feed wheel over a wrapping angle, which changes as a function of the thread tension at the point using thread. For this purpose, a so-called feeder lever is provided, which carries on its end an eyelet through which the thread runs. The lever is mounted so that it can pivot and is biased by a spring in the feeder direction, i.e., away from the thread feed wheel. If the thread tension breaks down, the feeder lever lifts the thread away from the thread feed wheel and drastically reduces at least the wrapping angle.
Such thread feeding devices have been proven in practice. Unlike positive feeding devices, however, they do not directly create a uniform mesh size.
The goal of the invention is to present a system, as well as a method, with which thread-processing machines, especially circular knitting machines, can be fed with thread in a way that allows increased stitch quality despite changing thread requirements.
To control the one or more thread feeding devices the control device according to the invention uses a pattern memory, which is used for controlling the knitting machine or some other textile machine. The pattern memory contains data for turning the thread feeding devices on and off at various positions of thread use, for example, stitching positions. Thus, the pattern memory controls, e.g., the lock of a knitting machine, in order to activate or deactivate individual needles, the thread feeder lever to lay thread in and out, cutting devices and the like. The control device has a pattern interface, by means of which it is connected to the pattern memory. In addition, the control device receives from a position sensor information on the current machine position. For a circular knitting machine, the term “machine position” is understood to be primarily the rotational angle of the needle cylinder. Here, the machine position can be detected either as an absolute position or as a relative position in the form of a pulse sequence or otherwise.
The central component of the control device is a processing module, which can also be designated as a machine interpreter, especially when it is realized in software. The processing module obtains data from the pattern memory according to the position of the machine and converts this data according to a set of given logic rules into control commands for the one or more thread feeding devices. The “set of given logic rules” can be a delay command in the simplest case. When the position sensor delivers, for example, a pulse sequence specifying the angular steps of the needle cylinder, and when the needle cylinder must rotate by a preset angle between the activation of a stitching position and the resulting thread requirements, there is the logic rule of waiting an appropriate number of pulses of the position sensor until a further request for thread is issued from the pattern memory to the thread feeding device. This can be realized with a gate circuit, which, after counting the relevant pulse number, forward the step pulses of the position sensor of the needle cylinder to the thread feeding device in order to cause the synchronous rotation between the thread feed wheel and needle cylinder with the desired delay.
The number of angular steps that pass between the activation of a certain point in the pattern and the required start of feeding can be viewed as the lag angle. In other cases, advance angles may also be necessary. This is easier to set when the position sensor is an absolute value sensor. The advance angle and/or lag angle are machine-specific and depend on, for example, the distance between a thread supply and feeder lever and a stitching position. For a given machine, they can be constant or dependent on settings or add-on parts. Preferably, they are stored in a data memory for machine data.
“Machine data” is, for example, a number of angular steps of the stitch cylinder or a number of other machine cycles that are executed after receiving a pattern command until the thread requirements actually change according to the pattern. Thus, the machine interpreter accesses both the pattern data memory and also the machine data memory and links these together (for example, through addition or subtraction of the advance angle or lag angle from the data of the pattern memory) and ensures that the feed wheel mechanisms are activated or deactivated at the correct point of the rotation of the needle cylinder. Instead of the access to the pattern memory, the machine interpreter can also be connected to a line that carries the pattern switching signals. Such lines are, for example, lines controlling switching elements of the knitting machine for activating or deactivating stitching positions. Thus, easily detectable control signals can be used that are used for controlling switching elements. In addition, signals of sensors that poll switching elements, needles, or other mechanical parts for executing pattern-specific actions can be used.
While activated thread feeding devices run-in sync with the needle cylinder, deactivated thread feeding devices are stationary. In addition to this switching operation, it can also be necessary to create at least temporary operating states in which the thread feeding devices are run at reduced rotational speed or also at overspeed.
For a simple embodiment, the advance and lag angles can be determined beforehand and programmed by service personnel or the machine manufacturer or the feed wheel mechanism manufacturer. However, it is also possible to provide an input interface, by means of which corresponding data, for example, screen masks, can be input. It is thus possible to test certain start and stop points relative to the rotation of the machine cylinder, and in this way to optimize the quality of the stitching to be created. It has also been found to be useful to establish positive thread feeding for jacquard circular knitting machines, wherein the thread feeding is not dependent on the current thread tension.
In addition, it is possible to provide thread tension sensors for simplifying the gathering of the machine data and to monitor the thread tension in a test operating mode as well as to activate the thread feeding devices only when tension appears in the thread. The rotational angle of the needle cylinder at which the thread tension appears can be compared to the associated pattern data. The angle differences between the pattern data and the rotational angles at which tension appears in the thread can be stored as advance angles or lag angles. After completing the test run, the thread tension sensor can be deactivated and pure positive operation can be performed with reference to the obtained data. If necessary, however, thread tension monitoring can be continuous or intermittent, e.g., in order to identify error states.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:
While the invention is susceptible of various modifications and alternative constructions, certain illustrated embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the invention.
In the following description, a number of reference numbers are used to refer to specific elements in the several drawings. These reference numerals correspond to the drawing elements as follows: Knitting machine (1); Needle cylinder (2); Needles (3); Lock (4); Lock cam (5); Line (7); Switching element (8, 8a); Actuator (8b); Branches (v); Points (12); Stitching positions (14); Thread (15); Hold points (16); Thread guide (17); Thread feeding devices (18, 19); Thread feed wheel (21); Motor (22); Control device (23); Processing module (23a); Position sensor (24); Position input (25); Control unit (26); Position input (27); Pattern memory (28); Data connection (29); Input device (31); Display device (32); Input masks (33); Data memory (34); and Thread tension sensor (35).
In
A switching device 8 can be used to activate or deactivate alternative branches 9, 11 of the lock cam 5. Additional switching elements and/or lock cams can be provided, but are omitted from
Downwardly extending positions 12 of the lock cam 5 guide the needles 3 downward to define stitching positions 14 at which a received thread 15 is formed into a stitch. The stitching positions 14 are preceded by holding points 16 at which the thread 15 is guided to the needles 3. The needles 3 are driven to the holding points 16 by the cam lock 5, e.g., by branch 9. Generally at the holding position 16, there is preferably a thread guide 17 for guiding the thread 15 toward or away from the needles 3.
In addition, the device 1 can also include cutting elements, pull-in devices, and the like, as will be appreciated by those of skill in the art. In order to improve clarity, such additional devices are omitted from
Thread feeding devices 18, 19, which may be identically or similarly constructed, are used for guiding the thread. The following description of the thread feeding device 18 applies equally to the thread feeding device 19 in an embodiment of the invention. Additional thread feeding devices (not shown) may also be used in keeping with this description.
The thread feeding device 18 has a thread feed wheel 21 coupled to a motor 22 to rotate therewith. The thread feed wheel is, for example, a bobbin formed of a barred cage or a one-piece part deep-drawn from sheet metal, and can have extended edges or guides on its ends and a cylindrical ribbed storage or receiving portion between the extended edges or guides. In use, the thread 15 wraps around the thread feed wheel 21 one or more times and thus forms a winding. The winding can contact the entire periphery of the thread feed wheel 21. In an alternative embodiment, the winding is guided over one or more thread lifting pins oriented approximately parallel to the rotational axis of the thread feed wheel 21. In this embodiment, the winding may contact only part of the periphery of the thread feed wheel 21. This technique can be used to allow a certain amount of slippage in the thread 15 on the thread feed wheel 21, so as to buffer feeding errors. In addition, a winding advance and/or an axial stretching of the winding can be achieved with the thread lifting pin, e.g., adjacent windings can be separated from each other. A high angular resolution position sensor preferably associated with the motor 22 allows the position of the motor 22 to be accurately sensed and controlled. In an embodiment of the invention, the accuracy of the position sensor is such that the feeding deviation of the thread 15 is less than 1 mm. A control device 23 is used to control the motor 22 based on the information provided by the sensor. The control device 23 controls the motor 22 by providing continuously updated angular information to the motor 22, such that the motor 22 rotates with continuous angular information. The angular information can be transmitted in the form of data, currents, voltages, pulses, i.e., step information, etc.
A second position sensor 24 is associated with the needle cylinder 2 to detect the current angular position of the cylinder 2. This position sensor 24 then forwards the angular position information, for example, in the form of increments, i.e., angular steps, to a position input 25 of the control device 23. In an embodiment of the invention wherein the angular position information is relative to the previous position rather than absolute, the position of the needle cylinder is preferably calibrated, such as once at start up, on each rotation, and/or at certain angular intervals. At the time of calibration, a zeroing signal is generated so that the control device can subsequently determine the absolute position of the needle cylinder 2 by counting the individual step pulses (increments). In an alternative embodiment of the invention, the position sensor 24 is an absolute value sensor that supplies an analog or digital signal characterizing the rotational angle of the needle cylinder 2 to the position input 25.
The knitting machine 1 is controlled by a control device 26, which has a position input 27 connected to the position sensor 24. The control device 26 controls the switching element 8 and also possibly other units of the knitting machine 1. For example, the control device 26 may control another switching element 8a shown schematically, an actuator 8b for moving the thread guide, cutting devices, and/or other elements.
The control device 26 is connected to a pattern data memory 28, which contains suitably prepared data characterizing the pattern of the knitted material to be created. An excerpt of the memory contents for a pattern that is continuous over several cylinder rotations is shown in
The control device 23 is also connected to this pattern memory 28. In this way it can retrieve the associated pattern data from the pattern memory 28 according to the position signals received via the position input 25. In
Having discussed the knitting machine 1 generally, the following section discusses the function of the control device 23 in the operation of knitting machine 1 in greater detail. In this embodiment of the invention, the knitting machine 1 is knitting plain-weave goods, although it will be appreciated that the described principles are more broadly applicable. In this case, the needle cylinder 2 runs at an essentially constant rotational speed. The rotational movement is detected in the form of individual increments or in the form of a sequence of absolute position information by the position sensor 24 and is forwarded to the control device 23 and also to the control unit 26. The stitching positions fed by the thread feeding devices 18, 19 are both active. Accordingly, the control device 23 controls the motors 22 of the thread feeding devices 18, 19 via control pulses and/or other appropriate control signals, so that the thread feed wheels 21 rotate with a given speed ratio in sync with the needle cylinder 2. The thread 15 is thus fed positively, i.e., at a predetermined rate. The needles 3 run through the top branch 9 of the lock cam symbolized by the line 7 and hold the thread, which is then stitched at the stitching position 14.
It is now assumed that a knitted material section is reached in which a pattern is to be generated. At this point, the control unit 26 receives the corresponding information by polling the pattern memory 28 and then switches the switching elements 8, 8a for the corresponding angular position of the needle cylinder 2 detected by the position sensor 24, so that the needles are no longer driven in and out and the loops are not sunk any further. For example, the feet 6 of the needles then run through the branch 11 of the lock cam, and also through the horizontal branch at the stitching position 14. Additionally or alternatively, the thread 15 can be pivoted outward by means of the actuator 8b and the thread guide 17, such that the thread 15 is no longer engaged by the needles 3. This is also a mechanism for interrupting the knitting operation when needed.
In either case (switching of elements 8, 8a or pivoting of the thread 15) the feeding operation of the associated thread feeding device 18 needs to be modified since the timing of the feeding lock no longer necessarily coincides with the timing of the switching of the switching element 8 or the actuator 8b. Instead, generally after the switching of elements 8, 8a, a portion of the needles are still located in the upward or downward extending lock cam (9, 12), that executes the loop-sinking movement, so that additional thread must still be delivered.
This phenomenon is shown diagrammatically in
In principle, advance angles αv can also be stored and maintained, so that the thread feeding starts shortly before the knitting machine 1 receives a corresponding switching command. Such advance angles are especially easy to maintain when the position sensor 24 is an absolute position sensor as opposed to a relative position sensor.
The necessary advance and lag angles for turning on and off stitching positions 14 or other measures that require an increase or decrease in the feed rate of the thread feeding devices 18, 19, are preferably stored in a data memory 34 which is part of the control device 23. The data stored in the data memory includes the mentioned advance or lag angles, and is input, for example, via the input device 31.
The lag angle αN1 can be obtained in the system of
The timing or rotational angle of the needle cylinder 2 at which the thread feed can be adjusted is the rotational angle at which the thread tension increases to an amount outside of the predetermined range. The control device 23 can record this associated rotational angle and it can be assigned to the pattern data of the pattern memory 28. This is realized, for example, by forming the difference between the angle at which the thread tension peak appeared and the angle at which a corresponding switching command was given to the switching element 8 or to the actuator 17. The difference is stored in the data memory 34 and may be later used in positive operation without tension monitoring in an embodiment of the invention.
Alternatively, the rotation of the thread feed wheel 21 can be monitored at the position of the detection of the thread tension peak. This involves the detection of the time or rotational angle of the needle cylinder 2 at which the rotation of the thread feed wheel 21 caused by the tension of thread 15 begins. The angular difference between the beginning of rotation of the thread feed wheel 21 and the angle at which the pattern memory 28 causes switching of the actuators or switching elements of the knitting machine 1 is in turn stored in the data memory 34.
In an embodiment of the invention, the advance angle and lag angle data obtained and stored in the data memory is editable. Optionally, a corresponding menu can be provided which can be invoked and operated via the input device 31 and the display device 32.
Optionally, certain rotational speed stages of the thread feed wheel 21 can also be monitored and registered in order to differentiate, for example, not only two states, e.g., active and inactive, but also a third state such as a “weak feeding” state involving the feeding of floating thread. During operation, the amount of thread fed is preferably determined according to the pattern information. As discussed above, the monitoring of the rotation of the thread feed wheel 21 or alternatively the thread tension is used to establish the angle of the needle cylinder 2 at which feeding of the thread 15 is to begin or stop, with reference to the pattern data. The data obtained in this way is then taken into account by the software operating the control device 21, which interprets the pattern data of the pattern memory 28 continuously, and determines the switching commands for the thread feeding devices 18, 19 with reference to the data stored in the data memory 34.
In an embodiment of the invention, the control device 23 is a central control device that is constructed independently of the control unit 26. Alternatively, the control device 23 is part of the same unit. Furthermore, it is possible to house the control device 23 in a thread feeding device 18, a separate unit, or in a network formed by the thread feeding devices 18, 19.
In an embodiment of the invention, the control device 23 is used for processing such secondary pattern signals, and may employ its self-learning mode. The control device 23 takes into account advance or lag angles between the switching signal and change in thread use. The advance and lag angles can be determined by manual input or with learning methods by monitoring the thread tension. Learning methods are especially suited for polling pattern data from switching lines. A point-exact turning on and off of the thread feeding devices can be achieved without manual input, without knowledge of the pattern data, and without knowledge of the machine data.
It will be appreciated that there has been described herein a novel system and control device for controlling thread feeding devices based on the data of a pattern memory or from pattern or switching data, wherein advance or lag angles which relate to the rotation of the needle cylinder for a specific machine are added to or subtracted from the pattern data. All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 017 045.2 | Apr 2004 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2005/002212 | 3/3/2005 | WO | 00 | 11/22/2006 |
