Patent Application
20230264923
The present invention relates to a device for rewinding yarns from a feed bobbin onto a bobbin tube to form a bobbin and having a machine frame and a bobbin mandrel, which is held in a rotationally fixed manner in the machine frame, for receiving the feed bobbin, and having a winding device and having a thread brake for setting a yarn tension.
Such devices are used for rewinding yarns in various forms in the textile industry. For example, conical dye bobbins are produced from cylindrical feed bobbins. In this case, the yarn is rewound from the feed bobbin onto a bobbin tube. A further application of rewinding machines involves a need for specific bobbin formats, for example, bobbin formats, which cannot be used in the actual production of the yarn due to their special sizes, are specified for sewing machines. A special requirement in terms of the type of winding can also make rewinding necessary. The devices for rewinding yarns comprise a bobbin mandrel for receiving the feed bobbin, a winding device and a thread brake. The bobbin mandrels are generally rotationally fixed since the feed bobbin does not rotate whilst the yarn is being drawn off. The yarn drawn off from the feed bobbin is guided to the winding device via a thread brake. The thread brake ensures a tension in the yarn whilst it is being wound onto the bobbin tube. Furthermore, in various textile machines, yarns are drawn off feed bobbins and processed further such as, for example, in weaving or knitting machines. In these cases too, the feed bobbins are held in a rotationally fixed manner on bobbin mandrels, and the yarn is removed freely from the feed bobbin.
The feed bobbin is emptied as the yarn is drawn off it. For the processing process, it is advantageous if, instead of said process being unexpectedly interrupted because yarn is lacking as a result of an empty feed bobbin, it can be stopped in a controlled manner. Remedying this problem has been attempted by measuring the weight of the feed bobbins. For example, US 20190330774 A1 discloses a device for weighing feed bobbins. In this case, the weighing device is provided with a damping device to prevent vibrations being transferred to the weighing device or to the weigh cells used when the feed bobbins are being changed. CN 103 981 631 B also discloses a weighing unit which can be used for weighing a feed bobbin during yarn removal.
The unwinding process causes a diameter of the feed bobbin to decrease steadily, which leads to the yarn coming off the feed bobbin more easily due to the latter's smaller diameter. The yarn tension between the yarn tensioner and the feed bobbin is thereby reduced. However, this also influences the yarn tension in the region of the winding device. This in turn leads to a change in the density of a bobbin over a winding cycle. This has a disadvantageous effect on certain applications, such as, for example, a winding of sewing yarn, where uniform density over an entire bobbin is important due to the subsequent processes in which the bobbin is used.
It is, therefore, an object of the present invention to propose a device and a method for rewinding a yarn from a feed bobbin onto a bobbin tube, which ensures a constant density of the wound-on windings over the entire winding cycle. Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
The problem is solved by a device and a method having the features described and claimed herein.
A device is proposed for rewinding yarns from a feed bobbin onto a bobbin tube to form a bobbin and having a controller and having a machine frame and a bobbin mandrel, which is held in a rotationally fixed manner in the machine frame for receiving the feed bobbin, and having a winding device and having a thread brake for setting a yarn tension. A holder of the bobbin mandrel comprises a weighing of the feed bobbin, wherein an adjustment of the thread brake is provided by the controller based on the weighing of the feed bobbin. The winding device for winding a yarn onto a bobbin tube to form a bobbin comprises a support roller rotatably mounted in the machine frame for supporting the bobbin tube and a tube receiver for holding the bobbin tube, wherein the tube receiver is held on a pivot lever which is rotatably mounted via corresponding supports on a rotary axis in the machine frame. The pivot lever can be designed with one or two pivot arms. Furthermore, the winding device comprises a cross-winding device for traversing the yarn along the bobbin tube, as a result of which a corresponding winding is formed on the bobbin tube.
The weighing system advantageously comprises a weigh cell and the weigh cell is arranged between the bobbin mandrel and the machine frame. The weigh cell can be arranged on both sides of the holder of the bobbin mandrel or integrated therein. Since the weigh cell is provided between the stationary holder of the bobbin mandrel and the machine frame, the weigh cell achieves a direct measurement of a weight of the feed bobbin placed thereupon after subtraction of the dead weight of the holder of the winding mandrel and of the winding mandrel itself. The weigh cell may be designed as a hydraulic or mechanical force measurement device. Advantageously, the force measurement device is designed as a load cell. This enables a simple and compact design in that the load cell can be designed as an element of the holder, and a load cell can also be coupled directly to a controller in a simple manner. Various types of so-called force transducers can be used in load cells. For example, the use of force transducers is known in which the force acts on a resilient spring body and deforms it. The deformation of the spring body is converted into a change in electrical voltage by means of strain gauges, the electrical resistance of which changes with the expansion. The electrical voltage and thus the change in strain are registered via a measuring amplifier. This can be converted into a force measurement value due to the resilient properties of the spring body. Bending bars, ring torsion springs, or other designs are used as spring bodies. Piezoceramic elements are used in a further type of load cell. The directional deformation of a piezoelectric material creates microscopic dipoles within the elementary cells of the piezoelectric crystal. The summation of the associated electrical field in all unit cells of the crystal leads to a macroscopically measurable electrical voltage, which can be converted into a force measurement value. Load cells are known from the prior art and are now widely used in force and weight measurement devices.
Preferably, a damping element is provided between the weigh cell and the bobbin mandrel. In order to keep vibrations, which, on the one hand, are transmitted by the machine frame and, on the other hand, arise from the drawing off of the yarn from the feed bobbin, from having an influence on the weighing a corresponding damping is advantageous. In this case, a simple elastic element can be used, which is inserted between the components.
The holder of the bobbin mandrel is advantageously provided in a feed table fastened in the machine frame, wherein the feed table is designed to be height-adjustable. The feed table is held in the form of a horizontal sheet in the machine frame and serves to fasten the holder or the force measurement device of the bobbin mandrel. As a result, the holder of the bobbin mandrel can be embedded in the feed table such that, with regard to the bobbin placed on the bobbin mandrel, it is possible to shield the force measurement device. The force measurement device is thus protected against contamination. At the same time, the feed table can be used as a support for the bobbin.
A height adjustability of the feed table facilitates the adjusting of a distance between the feed bobbin and the thread brake, which is fixed to the machine frame in a stationary manner. Adjusting said distance facilitates the adapting of the yarn course between the feed bobbin and the thread brake to the yarn to be wound and to the size of the feed bobbin. In a simple embodiment, the height adjustment is provided in steps. In this case, the feed table can be moved from one fastening plane into another. This is possible, for example, by hanging the feed table on mounting pins, wherein the mounting pins are provided in different fastening planes on the machine frame. A displacement of the feed table from a fastening plane into another fastening plane is carried out manually.
In a further development, the height adjustment of the feed table is provided to be continuous. In this case, the feed table can be held in corresponding guides in the machine frame and its height or its distance from the thread brake can be adjusted manually or by motor. Such a height adjustment saves the operating personnel from manually lifting the feed table as is the case in a simple stepwise adjusting device with rigidly provided mounting pins or lifting eyes. In addition, a continuous height adjustment has the advantage that, in the case of automation, the height of the feed table can be adjusted by the controller.
An input device for inputting a specification of the feed bobbin and certain winding parameters is advantageously provided in the controller. The specification of the feed bobbin comprises, for example, information about the yarn on the feed bobbin, in terms of type and yarn thickness, as well as the size of the feed bobbin. The winding parameters include, inter alia, information about the bobbin size, winding speed, bobbin density, winding type or type of bobbin tube. With the aid of these data, the controller can calculate the necessary settings of the thread brake before and during a winding cycle as a function of the remaining bobbin weight.
It is advantageous for a visual or acoustic signal to be provided when a target weight of the feed bobbin is undershot. If a certain target weight of the feed bobbin is undershot, only the bobbin located in the winding device can be produced. However, there will then be too little yarn remaining on the feed bobbin for a further bobbin. The signal makes the operating personnel aware that the feed bobbin has to be changed for the further rewinding operation.
Furthermore, a method for rewinding a yarn from a feed bobbin onto a bobbin tube is proposed, wherein a device according to the preceding description is provided. The controller is used to calculate an actual weight of the feed bobbin from the weighing and a change is made to the setting of the thread brake on the basis of the actual weight. The actual weight of the feed bobbin is directly proportional to a yarn quantity that is still present on the feed bobbin and thus also to a diameter of the feed bobbin. In the case of the feed bobbin having a large diameter, as a result of the path which the yarn has to traverse around the feed bobbin when the yarn is being unwound, a greater yarn tension is produced than in the case of a bobbin with a smaller diameter. This prevailing yarn tension upstream of the thread brake acts directly on the yarn tension downstream of the thread brake, since the thread brake, as a result of a position of deflector elements around which the yarn is deflected, only effects an increase in the existing yarn tension.
Advantageously, the actual weight is calculated in each case when the winding device is at a standstill for calibration of the process. Due to the movements of the feed bobbin during an unwinding process and the vibrations due to the operation of the rewinding machine, measuring the weight of the feed bobbin when the winding device is at a standstill is the most reliable. Since the winding device is stationary during each change of the bobbin tube, an exact measurement of the weight of the feed bobbin can be carried out at this time and the values determined in this case can be used as the basis of the calculations when the winding of a new bobbin tube is started. In this way, slight deviations or measurement inaccuracies can also be detected and corrected and are not therefore transferred to subsequent winding processes.
Preferably, the controller prevents the winding device from restarting when a target weight of the feed bobbin is undershot. Since, due to the measurement of the weight of the feed bobbin, the controller knows how much weight the feed bobbin loses during a winding of a bobbin tube, the controller can prevent the winding of an empty bobbin tube from beginning if too little yarn is present on the feed bobbin to be able to conclude the winding process. This prevents bobbin tubes that are not completely wound from being produced.
It is advantageous for the controller to assign a corresponding setting of the thread brake to the respective weight of the feed bobbin on the basis of a specification of the feed bobbin input into the controller and of winding parameters. As a result, it can not only be achieved that a change in the weight of the feed bobbin is fed into the setting of the thread brake, but also a specific basic setting are carried out independently by the controller. As a result, a basic setting carried out once can be easily repeated if the same bobbin tubes are to be wound with the same yarn.
Preferably, a winding machine or a rewinding machine is equipped with a device according to the above description.
Further advantages of the invention are described in the following embodiment. In the drawings:
Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.
The yarn 3 coming off the feed bobbin 17 is guided after the feed bobbin 17 (when viewed in the yarn running direction) via the thread brake 16 and then through a cross-winding device 15 before it reaches the support roller 12 and is wound onto the bobbin tube 5. The cross-winding device serves to move the yarn 3 back and forth parallel to a surface of the bobbin 2 in the direction of the bobbin axis 8 in order to achieve uniform winding or a predetermined winding characteristic. The feed bobbin 17 is held on a bobbin mandrel 18, wherein the bobbin mandrel 18 is fastened in the machine frame 26 via a holder 19. The bobbin mandrel 18 can be fastened rotatably or in a rotationally fixed manner in the holder 19. Depending on the type of fastening, the feed bobbin 17 is held movably on the bobbin mandrel 18 or the bobbin mandrel 18 is held movably in the holder 19.
The measurement data of the force measurement device are forwarded to a controller 27 and evaluated therein. The controller 27 is also connected to the winding device 1 in order to send the necessary signals to the drives of the winding device 1. This is necessary, for example, if further operation of the winding device 1 is to be prevented because there is too little yarn on the feed bobbin 17 for a bobbin to be formed. Furthermore, an input device 29 is connected to the controller 27. By means of the input device 29, the operating personnel can input data required for the operation of the winding.
The present invention is not limited to the embodiments as shown and described. Modifications within the scope of the claims are possible, as well as a combination of the features, even if these are shown and described in different embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 000158/2022 | Feb 2022 | CH | national |
