EP1643026B1 - Knitting machine with a magnetic needle selection system for knitting patterned fabrics - Google Patents

Description

The invention relates to a knitting machine, in particular a flat knitting machine according to the preamble of claim 1.

Knitting machines with needle selection systems are for example in the DE-AS 1 585 206 and in the DE-PS 36 14 220 described. These systems are characterized by the fact that with the aid of permanent magnets, a holding force for the selection elements of the needles of the knitting machine are generated. In certain areas of the permanent magnets, the holding force can be compensated by means of electromagnetic coils, so that the needle selection elements can be dropped at these locations by the needle selection system. Depending on the knitting pattern currently selected, certain needles are thus selected using the needle selection system and others are not. It is important that the coils are energized to compensate for the holding force of the permanent magnet so that the magnetic field for the one needle selection element that is to fall off, is compensated in the correct strength. This is in the DE-PS 36 14 220 proposed that in the discharge areas of the selection magnet, where a compensation of the magnetic field can take place, a measuring head is arranged, which detects the size of the magnetic field in the discharge area. Depending on the measurement result, the current value for the control coil optimally adjusted to ensure safe ejection of the needle selection element.

In the EP 1 026 299 A1 It is proposed to regulate the current intensity of the control coil for the ejection of a needle selection element corresponding to the number of needle selection elements which are currently magnetically adhering to the selection system. The number of needle selection elements currently attracted by the selection magnet is determined by software from the pattern control program.

Both the current regulation according to the DE-PS 36 14 220 as well as the EP 1 026 299 A1 are relatively expensive.

The DE 40 24 742 A1 also describes a knitting machine having a needle selection system that includes permanent magnets for attracting needle selection elements and solenoids for ejecting needle selection elements. The current through the coils of the electromagnets is controllable. In order to reduce the friction between the needle selection system and the needle selection elements, ferromagnetic intermediate elements are arranged opposite the needle selection system in the area of the needle selection elements. However, such ferromagnetic components are absent in the peripheral regions of the movement space of the needle selection system.

The present invention has for its object to improve a knitting machine with a needle selection system of the type mentioned in such a way that is guaranteed without a power regulation safe ejection of the desired needle selection elements in all cases occurring.

The object is achieved with a knitting machine with the features of claim 1.

The energization of the at least one coil in the discharge area of the selection system with a constant current profile eliminates the need for measuring devices or evaluations of the patterning program, so that the needle selection system becomes simpler in design and control technology. Nevertheless, the needle selection system is just as reliable as the known needle selection systems with current regulation. This is achieved by the magnetic damping of the selection magnet arrangement being approximately constant over its entire range of motion.

Magnetic damping primarily occurs through the ferromagnetic material of the needle bed or needle cylinder or a selection board bed. Further magnetic damping is produced by the selection elements currently attracted by the selection magnet arrangement. If, therefore, the primary magnetic damping is kept constant over the entire range of motion of the needle selection system, it is no longer necessary to determine how many needle selection elements have just been tightened. According to the invention, a constant primary damping is achieved in that the selection magnet arrangement is disposed opposite to ferromagnetic material over its entire range of motion. The ferromagnetic components may be formed by a needle bed grooved to the needle guide or a grooved selection board bed and ungreased areas of the needle bed or selection board bed.

In this embodiment, therefore, the needle beds or selection board beds are extended on both sides beyond the grooved area. Thus, the selection magnet arrangement faces ferromagnetic material over its entire path, which extends beyond the needle area on both sides, which effects uniform damping of the permanent magnetic field.

In another embodiment, the ferromagnetic components can be formed by the grooved area of a needle bed or a selection board bed of a flat knitting machine and ferromagnetic strips arranged laterally of the grooved area. The strips may preferably have the same thickness as the needle bed or the selection board bed and at least the same width as the selection magnet arrangement. As a result, it is possible in the lateral areas of the bed to achieve identical damping conditions as possible over the grooved area of the bed.

Another way to achieve the most homogeneous possible primary attenuation of the magnetic field of the selection magnet arrangement is to select the distance between the selection magnet arrangement and the un-grooved areas of the needle bed or selection board bed or the strips in such a way that the selection magnet arrangement over these areas or strips the same magnetic damping is experienced as by the ferromagnetic material of the grooved area of the needle bed or selection board bed. Different damping properties due to the use of the bed in comparison to an un-groomed area of the bed or a bar attached to the bed can thereby be compensated.

Hereinafter, a preferred embodiment of a selection system according to the invention will be described with reference to the drawings.

Fig. 1

einen Querschnitt durch ein Nadelbett einer Flachstrickmaschine mit einer darüber angeordneten Nadelauswahleinrichtung;

Fig. 2

einen schematischen Teilschnitt durch das Nadelbett und die Nadelauswahleinrichtung aus Fig. 1 entlang der Linie II-II;

Fig.3

eine Ansicht von oben auf das Nadelbett und die Nadelauswahleinrichtung gemäß Fig. 2 bei Positionierung des Nadelauswahlsystems im Endbereich des Nadelbetts.

In detail show:

Fig. 1

a cross section through a needle bed of a flat knitting machine with a needle selection device arranged above it;

Fig. 2

a schematic partial section through the needle bed and the needle selector Fig. 1 along the line II-II;

Figure 3

a view from above of the needle bed and the needle selector according to Fig. 2 positioning the needle selection system in the end area of the needle bed.

Fig. 1 shows a needle selection system 100 of a flat knitting machine, of which a needle bed 3 is shown in cross section. The needle bed 3 is cut so that a needle channel 31 is visible. In the needle channel 31, a needle 4 is guided longitudinally displaceable. A needle movement initiating board 5 and a pusher 6 are also longitudinally displaceable and also arranged to be movable perpendicular thereto. As a needle selection element, a selection board 7 is provided, which can also perform a pivotal movement in addition to a sliding movement along the channel 31. In the example shown, the selection board 7 bears against a contact surface 71 on the underside of the needle selection system 1. It is held in this position by magnetic forces against the force of a leg spring 8. In the illustrated Position is the selection board 7 inactive. If, on the other hand, it wishes to select the needle 4 assigned to it, the magnetic force of the needle selection system 1 is compensated electromagnetically. The board 7 then pivots due to the force of the leg spring 8 in its active position. In this position, it can then cause a propulsion of the needle 4 by the action of lock curves.

The needle selection system 1 is rigidly fastened to a carriage 2, which is only schematically indicated here. Between the magnetic poles of the selection system and the top of the needle bed 3, which consists of a ferromagnetic material, preferably made of steel, a gap of the width Z2 is provided, which is constant over the entire needle bed length.

Fig. 2 It illustrates a construction of the needle selection system 1. It has a selection magnet arrangement 10 with a holding region H within which needle selection elements, here the needle selection plates 7, are held by the magnetic force of at least one permanent magnet 12. Within the holding area H are also two discharge areas 11, 11 '. In these areas, by exciting electromagnetic coils 13, the magnetic force of the permanent magnet 12 can be compensated so that the selection boards 7 are dropped from the needle selection system 1.

In the illustrated example, the needle selection system 1 moves in the direction of arrow X over the needle bed 3 away. The selection board 7 'is not yet within the influence range of the selection magnet arrangement 10. The selection board 7 ", on the other hand, has been dropped off at one of the discharge points 11, 11. It is now located at a distance below a slide strip 11 which closes the permanent magnet 12 downwards. On the other hand, the selection boards 7 rest against the sliding strip 11. With Z2 again the distance of the needle bed 3 to the pole face of the selection magnet assembly 10 is designated. The magnetic field formed by the permanent magnet (s) 12 undergoes primary damping by the ferromagnetic material of the needle bed 3 and further secondary damping by the selection boards 7.

In Fig. 3 is shown in a view from above the needle selection system 1 in its extreme end position. It has moved so far beyond the needle bed 3 in the direction of the arrow X that the outermost selection board 7 can be influenced by the innermost discharge area 11 'of the selection system 1. At least to this position must in the needle selection device according to the invention, in which the magnetic coils 13 are applied in the region of the drop zones 11, 11 'with a constant current profile, the needle selection system 1 is a primary attenuation by the ferromagnetic material obtained, so that a safe ejection of the guaranteed to be activated needle selection elements. For this purpose, the needle bed 3 has been extended laterally over the grooved area in the illustrated example. The distance of the ungrooved area 3 'to the selection magnet arrangement 10 can be different from the distance Z2 to the grooved area of the needle bed 3. Instead of the needle bed 3, a selection board bed can also be provided, via which the needle selection takes place. If, for structural reasons, the needle bed 3 can not laterally extend beyond the grooved area, strips of ferromagnetic material not shown here can also be arranged laterally of the needle bed 3, which preferably have the same thickness and at least the width of the selection magnet arrangement 10. The distance between the bar and the selection system 1 can be constant or adjustable.

As a result, at least approximately constant primary damping ratios can be created for the needle selection system 1 over the entire range of motion, so that a regulation of the current profile of the coils 13 can be dispensed with.

Claims (6)

1. Knitting machine, in particular a flat knitting machine, with a patterning device with a needle selection system with at least one selection magnet arrangement (10) which comprises at least one permanently magnetic holding region (H) and at least one discarding region (11, 11'), to which at least one controllable coil (13, 13') is assigned, needle selection elements (7, 7', 7") being able to be pulled against the selection magnet arrangement (10) and components (3, 3') made of ferromagnetic material being arranged opposite the selection magnet arrangement (10), characterised in that the at least one coil (13, 13') is controlled upon the discard of a needle selection element (7, 7', 7") with a constant current strength profile which is independent of the number of the needle selection elements (7) each pulled from the selection magnet arrangement (10), and in that the components (3, 3') made of ferromagnetic material are arranged opposite the at least one selection magnet arrangement (10) over its entire movement region in such a way that the magnetic damping of the selection magnet arrangement (10) is roughly constant across the entire movement region thereof.
2. Knitting machine according to claim 1, characterised in that the ferromagnetic components are formed by a needle bed (3) which is grooved for the purpose of needle guidance or by a selector bed and ungrooved regions of the needle bed (3) or of the selector bed of a flat knitting machine.
3. Knitting machine according to claim 1, characterised in that the ferromagnetic components are formed by a grooved region of a needle bed (3) or selector bed of a flat knitting machine and by ferromagnetic strips arranged laterally to the grooved region.
4. Knitting machine according to claim 3, characterised in that the strips are as strong as the needle bed (3) or the selector bed and are at least as wide as the selection magnet arrangement (10).
5. Knitting machine according to either claim 3 or claim 4, characterised in that the distance between the selection magnet arrangement (10) and the grooved region of the needle bed (3) or selector bed differs from the distance between the selection magnet arrangement (10) and the ungrooved regions (3') of the needle bed (3) or of the selector bed or the strips.
6. Knitting machine according to any one of claims 3 to 5, characterised in that the distance between the selection magnet arrangement (10) and ungrooved regions (3') of the needle bed (3) or of the selector bed or the strips is such that the selection magnet arrangement (10) experiences the same magnetic damping over these regions (3') or strips as through the ferromagnetic material of the grooved region of the needle bed (3) or of the selector bed.

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