EP0063371B1 - Knitting machine for the production of a striped fabric - Google Patents

Description

The invention relates to a knitting machine of the type specified in the preamble of claim 1.

In a knitting machine of this type known from FR-A 616779, a mechanical selection unit with a lever, a selection cam, a selection arm and a selection element for the guide fingers assigned to the different yarns is provided, which is also controlled mechanically by a chain wheel driven as a function of the machine speed and a timing chain is operated depending on the pattern. The yarn splice holding and cutting device ties the individual yarn sections together to form the continuous yarn, which is drawn into the knitting station of the knitting machine via the intermediate storage device. The intermediate storage device is a structure standing above the yarn splicing, holding and cutting device with a spring-loaded swivel arm which carries a yarn eyelet and forms a yarn supply loop. The lengths of the individual thread sections are specified via the timing chain. When a knot is formed, the running yarn must be stopped temporarily. This intermittent yarn movement compensates the intermediate storage device in that the swivel arm carrying the yarn eyelet, which is spring-loaded, changes the length of the yarn supply loop. This results in the disadvantage that the later position of each knot in the goods cannot be predicted precisely, since the intermediate storage device is passive when the yarn supply loop is provided and only works as a function of frictional forces, the elasticity of the yarn and the pretensioning of the swivel arm. In the year of registration (1926) of this prior publication, this disadvantage still had to be accepted, especially since its effect on a single-system circular knitting machine is still acceptable. In modern knitting machines, especially multi-system knitting machines, this leads to unusable quality of the goods.

The invention has for its object to provide a knitting machine of the type mentioned, in which the knots between the yarn sections of different colors come to lie in precisely predetermined positions in the knitted striped fabric.

The object is achieved according to the invention by the features specified in the characterizing part of patent claim 1.

Since the auxiliary control unit receives all the information that is important for the setting of the nodes, it can control the node formation in a precisely predeterminable manner in such a way that the nodes in the finished striped goods come to lie in precisely predetermined positions which are considered to be favorable. In the case of a circular ring knitting machine, all the knots formed are best placed in the needle-free area of the needle cylinder, while in the case of a flat ring knitting machine, for example, all the knots are set where the knitting system reverses its movement. The yarn movement between the yarn splicing, holding and cutting device and the knitting system is no longer subject to chance or fluctuations in friction or elasticity, but is actively managed and controlled by the auxiliary control device.

An expedient embodiment emerges from claim 2. With the positive yarn feed device, the yarn is presented to the knitting system with constant and low yarn tension, so that a high working speed can be achieved even with multi-system knitting machines.

Another useful embodiment is set out in claim 3. The sensors determine the information for the auxiliary control unit, which can be arranged separately from the sensors on the knitting machine. The often limited space in the individual work stations on the knitting machine is taken into account, since the sensors take up little space in relation to the auxiliary control unit. Another advantageous embodiment is set out in claim 4. On the jacket of the drum, the intermediate supply of the yarn is provided in the precisely predetermined length so that the positive feed device can feed the yarn with the low and constant yarn tension to the knitting system.

The idea of claim 5 is also important, since after the drive of the supply-forming element is stopped, the knot formation takes place undisturbed.

Finally, the feature of claim 6 is also expedient, since a positive feed device in the form of a tape feeder works very reliably and takes up little space. Particularly in the case of multi-system circular circular knitting machines, the corresponding number of positive feed devices are combined to form a jointly driven feed complex, the individual positive feed to each knitting system being guaranteed.

An embodiment of the subject matter of the invention is explained below with reference to the drawings.

• Fig. 1 schematisch eine Ringel-Rundstrickmaschine, und
• Fig. 2 bis 8 ein Detail aus der Rundstrickmaschine von Fig. in verschiedenen Arbeitsphasen.

Show it:

• Fig. 1 shows schematically a ringlet circular knitting machine, and
• Fig. 2 to 8 shows a detail from the circular knitting machine of Fig. In different working phases.

A conventional knitting machine 1 shown schematically in FIG. 1 has a rotating needle cylinder 1a, along the circumference of which needles 2 are guided in grooves in a longitudinally displaceable manner. A knitting system 3 leads to knitting de yarn in a position in which it can be gripped by the needles 2. Several knitting systems 3 are arranged in a fixed manner along the circumference of the needle cylinder 1a. In the embodiment shown, the needle cylinder 1a has a peripheral section 1b that is not equipped with needles.

The knitting machine 1 is otherwise of conventional design and therefore need not be described in detail. In contrast to a conventional knitting machine, the knitting machine 1 shown is intended for the production of striped goods S. The goods S have successive strips A-D of different colors in a predetermined sequence.

For the formation of these strips, yarns of the corresponding colors a to d are present in the form of packs or bobbins 4, which are arranged in a conventional manner on a support ring of the knitting machine or a separate bobbin frame. For the selection of the yarn required in each order, a yarn selection unit 5 is provided, as is directly assigned to each individual knitting system in a known knitting machine for the production of horizontally striped goods. The selection unit 5 selects one of the four different-colored yarns a-d, for example, in the same way as is done directly by the respective knitting system in a conventional knitting machine for striped goods.

A splicing, holding and cutting device 6 directly adjoins the selection unit 5. This can be a conventional splicing or knotting device, which attaches a thread running in from the selection unit 5 to a running, endless thread strand 7 and cuts off the thread previously attached to the strand 7 and holds the cut end.

A fixed intermediate storage drum 8 is arranged on the outlet side of the device 6. The endless yarn strand 7 is driven by a drive 10, e.g. an electric motor, connected winding element 9 wound on the drum 8. Such buffers for the intermittent feeding of yarn to a knitting machine or a loom are generally known.

A positive feed device 11 pulls the yarn strand 7 from the storage drum 8 and feeds it to the knitting system 3 of the knitting machine 1. In the embodiment shown, the feed device 11 is a belt feeder in which the yarn is clamped between a driven belt 11 and rotatable pinch rollers 11b. Such tape feeders for positive yarn feed to a knitting machine are generally known.

A control arrangement that controls the entire workflow has a sample unit 12 and a secondary or auxiliary control unit 13. The auxiliary control unit is fed with the output signals of a first sensor 14 assigned to the winding element 9, a second sensor 15 assigned to the positive feed device 11 and a third sensor 16 assigned to the needle cylinder 1a of the knitting machine 1.

The control takes place in the following way: The pattern unit 13 works synchronously with the working cycle of the knitting machine 1 and feeds the yarn selection unit 5 with control pulses according to a pattern program stored in the pattern unit, as indicated by an arrow A1. According to the signals A1, the selection unit 5 selects one of the four yarns a-d. The pattern unit 12 thus determines the width of the strips A-D of the fabric S or, in other words, the number of stitch rows of each strip.

The secondary or auxiliary control unit 13 determines the exact point in time at which the respectively selected yarn a, b, c or d is added to the running yarn strand 7 by the device 6. The corresponding control signal is indicated by an arrow A2. Simultaneously with this, the auxiliary control unit 13 feeds the drive 10 of the winding element 9 with a signal indicated by an arrow A3 for switching off the drive, so that the splicing or knotting can take place while the yarn strand 7 is not moving in the device 6. The signal A3 leads the signal A2 slightly, since a certain period of time passes until the drive 10 comes to a standstill. The drive 10 is preferably a stepping motor, which can be stopped in a precisely determined angular position and accelerates quickly.

The auxiliary control unit 13 is fed by the pattern unit 12 with pattern information indicated by an arrow A4. The pattern unit 12 thus determines the approximate time and the auxiliary control unit 13 the exact time at which a color change takes place.

An essential task of the auxiliary control unit 13 is to precisely determine the length of the differently colored yarn sections of the yarn strand 7, so that the stripe pattern of the goods S is exactly maintained. For this purpose, the sensor 14 feeds the auxiliary control unit 13, as indicated by an arrow A5, with the information corresponding to the exact position of the winding element 9. This can be done in such a way that the sensor 14 generates pulses corresponding to the revolutions of the winding element 9.

Furthermore, the auxiliary control unit 13, as indicated by an arrow A6, is fed by the sensor 15 with information corresponding to the drive speed of the belt 11a. The sensor 15 can be an optical sensor which responds to optical signals from reflectors arranged on the band 11a or the rollers 11b.

The information transmitted to unit 13 by signals A5 corresponds to the length of that wound on storage drum 8 Yarn. The information transmitted by the sensor 15 in the form of the signals A6 corresponds to the length of the yarn drawn off from the storage drum 8 by the positive feed device 11. The length of the yarn between the splice in the device 6 and the winding element 9 is constant. Since the auxiliary control unit 13 generates the splice signal A2, it contains information about the length of the yarn present between the splice point and the knitting machine at all times. As a result, the auxiliary control unit 13 can emit the splice signal A2 at a time which corresponds to the exact length of the yarn of a specific color required for the pattern to be produced.

In addition, the auxiliary control unit 13 continuously controls the speed of the drive 10 via the signal A3 in order to adapt it to the yarn consumption determined by the sensor 15. In this way, the intermediate yarn supply on the drum 8 can be kept within a narrow range, and changes in speed of the winding drive can be kept to a minimum.

The control arrangement described makes it possible to set the splices or knots of the endless yarn strand 7 such that they always come to rest in the section 1 b of the needle cylinder which is not equipped with needles. The finished goods are then cut open along the area spanning this section, so that the splices or knots lie in an uncritical area of the goods.

The auxiliary control unit 13 feeds the sensor 16, which can likewise be an optical sensor and interact with reflectors on the needle cylinder 1a, with the exact position of the needle cylinder 1a, which information can be used as a correction factor. In this way, errors caused by irregularities in the drive of the knitting machine, e.g. prevent the nodes from moving into areas not intended for this purpose.

The arrangement described enables the production of a high-quality striped goods with a precisely defined stripe pattern on an ordinary knitting machine. The density or the quality of the striped goods can be varied by changing the speed of the positive feed device 11.

The various units and devices 5, 6, 10, 9, 8 and 11 can be arranged at a certain distance above or outside the knitting machine 1, so that the entire arrangement is easily accessible for maintenance and repair purposes.

2 to 8 show the structure and the work in the binding station 6 schematically indicated in FIG. 1, which contains a yarn splicing, holding and cutting device.

In Fig. 2 four identical yarn clamping and cutting devices 20a, 20b, 20c and 20d can be seen, which are optionally mounted on stationary plates 21a, 21b, 21c and 21d so as to be displaceable and pivotable. As will be explained in detail below, these devices can be controlled in such a way that they feed the respective yarn a, b, c, and d, which runs from the yarn bobbins 4a, 4b, 4c and 4d, into a knotting or splicing station 22 ' a knot or splicer 22 of known type. The splicing device can, for example, carry out the splicing process in an electrostatic manner.

3 to 8 emphasize more clearly, the respective yarn clamping and cutting device 20, in this case 20b, is displaceable and pivotable in a groove 21 'of a stationary plate 21 against the force of a spring 23. A head 20 _'of the yarn clamping and cutting device 20 has a central plate 24 with a longitudinal groove 24' (see FIG. 2). Further plates 25 and 26 are connected on both sides of the middle plate 24 via a bolt connection 27 through the groove 24 '. One plate 25 forms a cutting blade for the yarn. Stop surfaces 25 'and 26' are arranged on the two plates 25 and 26. Furthermore, a curved yarn clamping blade 28 is fastened to the plates 25 and 26 via a bolt connection 27. As a result of the groove 24 ', the plates 25 and 26 and the blade 28 are displaceable relative to the central plate 24'. This mobility is used when controlling the respective thread clamping and thread cutting operations at the desired times, the stop surfaces 25 'and 26' cooperating with first and second stationary stops 29 and 30. The yarn clamping and cutting device 20 can be pivoted after excitation of a linear magnet 31, which acts on a surface 20 "of the device 20. After excitation of a rotary magnet (not shown), a control plate 32 is also pivoted, which the device 20 by cooperation of a first Control pin 33 pivoted and displaced on the plate 32 and a control groove 34 of the device 20, a relative movement also taking place between a second control pin 35 on the plate 32 and a control surface 36 on the device 20.

The function of the yarn clamping and cutting device 20 is described below with reference to FIGS. 3 to 8, provided that a length section of a yarn b is selected and connected to an already running yarn a to form a continuous yarn strand, the yarn strand then is fed to the knitting machine.

In FIG. 3 it can be seen how the yarn a runs from the yarn spool 4a between stationary yarn eyelets 37 and 38, which approximately limit the knot or splicing station 22 'of the device 22. At a predetermined point in time, the pattern unit 12 (FIG. 1) delivers an exciting pulse to the linear electromagnet 31, so that its impacts) 31 'presses on the control surface 20 ", as shown in FIG. 4. The device 20b 4 moves to the left in such a way that the control groove 34 comes into contact with the first control pin 33. In the next moment, the rotary magnet (not shown) receives an exciting impulse from the second control unit 13 (FIG. 1), whereby the control plate 32 is rotated counterclockwise (FIG. 5) and the yarn clamping and cutting device 20b into a swivel end position twisted, which can be seen from Fig. 6. During this movement of the device 20b, the yarn b is guided laterally as a result of the correspondingly designed surface 22 "of the yarn knot or splicing device 22 (FIG. 2) and is moved within the knot or splicing area 22 'to the yarn a still running, so that it finally comes to lie close to this and parallel to it.

In the next moment, the second control unit 13 emits a stopping pulse to the drive 10, so that the winding up of the yarn a is interrupted and the yarn a is stopped for a brief moment within the knotting or splicing device 22. In the next step, the second control unit 13 sends a start impulse to the device 22, whereupon the now standing yarns a and b are knotted or spliced to one another, specifically in the area 22 _' .

As soon as this step, which takes only a short time, has been carried out, the device 20b is moved further downward, specifically by the second control pin 35, which presses on the control surface 36 according to FIG. 7b. As a result, since the first holding stop 29 now acts on the holding surface 25 ′, the middle plate 24 is displaced relative to the clamping blade 28, so that the end of the yarn b clamped up to that point is released.

At the time when the yarn b is released, the yarn clamping and cutting device 20a for the yarn a is in the position according to FIG. 7a. It is now shifted upwards by the control edge 39, which engages in the control groove 34. Since the second stop 30 now acts on the stop surface 26, the middle plate 24 is displaced relative to the cutting blade 25 and the clamping blade 28, so that the yarn a is cut off in the direction of the knot or splice point, while the end of the yarn a that is in the opposite direction is clamped. This means that the yarn a has reached a position again, comparable to that of the yarn b in FIG. 3, in which it is ready for a new selection.

The last step in the yarn selection and splicing operation is that the device 20b, after energizing the rotating magnet, but then in the clockwise direction, through the first control pin 33, which engages in the control groove 34, and with the force of the spring 23 is moved back into the position shown in Fig. 8. As a result of the specific design of the control plate 24 with its hook-shaped control groove 24 ", the yarn b, which is now continuously moved, is moved into the groove 24", which enables the device 20b to then cut the yarn b and hold it when another yarn , e.g. Yarn c or yarn d will need to be joined to yarn b currently being moved continuously.

Claims (6)

1. A knitting machine (1) for making striped fabrics of differently coloured yarns (a, b, c, d) selected from a yarn supply (4) by means of a selector unit (5), a yarn splicing apparatus (6) associated with said selector unit being operable to splice yarn portions of lengths determined by the knitting pattern to form a continuous yarn (7) to be fed to a knitting system (3) via a buffer storage device (8), said selector unit being controlled by a pattern unit (12) provided in a control system, characterized in that said control system additionally includes an auxiliary control unit (13) supplied with pattern informations and with informations representing the yarn length consumed by the knitting machine (1), the yarn length stored in said buffer storage devide (8), and the operating position of the knitting machine at the given instant, respectively, and in that said auxiliary control unit (13) is operable to control said yarn splicing or yarn knotting apparatus (6) and a drive means (10) for a storage-forming element (9) of said buffer storage device (8).

2. A knitting machine according to claim 1, characterized in that a positive yarn feeding device (11) is located downstream of said buffer storage device (8) in the yarn feed direction.

3. A knitting machine according to claims 1 and 2, characterized in that sensors (14, 15) for determining the respective yarn lengths are provided adjacent the drive means (10) of said storage-forming element (9) and adjacent said positive feed device (11), and a sensor (15) for determining the respective operating position of the knitting machine (1) is provided on said knitting machine, said sensors being connected to said auxiliary control unit (13).

4. A knitting machine according to claims 1 to 3, characterized in that said buffer storage device (8) is a stationary drum, and said storage-forming element (9) is a winding-on-element being allocated the drum periphery and adapted to be driven by a step-by-step motor (10).

5. A knitting machine according to at least one of claims 1 to 4, characterized in that said drive means (10) for said storage-forming element (9) is adapted to be stopped by said auxiliary control unit (13) during the knitting operation.

6. A knitting machine according to any of claims 1 to 5 characterized in that said positive feed device (11) is a belt feed apparatus.

Images