GB2247471A - Electromagnetic needle selector for circular knitting machines - Google Patents

Description

ELECTROMAGNETIC NEEDLE SELECTOR FOR CIRCULAR KNITTING MACHINES This invention relates to an electromagnetically actuated needle selector for circular knitting machines such as those for the production of hosiery, and with the possible capability of creating patterns on the knitted fabric under electronic control.

GB-2138847-A published Oct. 31, 1984 and JP-6147856-A published March 8, 1986 are hereby cited as the prior art that is believed to be closest to the instant invention. The former application suggests a needle selector including an upright knitting cylinder carrying multiple needle jacks slidably received in as many grooves cut longitudinally in its surface. The needle jacks are to be selectively raised for creating patterns on the fabric being knitted.

For selectively lifting the needle jacks on the knitting cylinder, the application first cited employs a vertical stack of L-shaped selector levers pivotable about a common vertical axis. Each selector lever has a twisted tip at one end for engaging and pushing up the butt of each selected needle jack and carries three permanent magnets in a horizontal row on the other end.

Disposed adjacent to said other ends of the selector levers are pairs of electromagnets forming a vertical row. As each pair of electromagnets are alternately excited in opposite directions, the corresponding selector. lever -is swung back and forth by the attractive and repulsive forces exerted between the pair of electromagnets and the three permanent magnets on - the selector lever. The twisted tips of the selector levers will then act on the butts of the needle jacks on the knitting cylinder, which rotates at high speed, to lift the desired needles.

An objection to this prior art needle selector is the large vertical dimension necessitated by the vertical stacking of the pairs of electromagnets. Furthermore, since the self-excited vibration of the electromagnets upon energization, is transmitted directly to the needle jacks via the selector levers, the prior art device generates considerable noise and vibration and the twisted tips of the selector levers are subject to rapid wear. Such vibration is all the more objectionable because it impedes the positive actuation of the selector levers, and hence of the needle jacks, by the electromagnet pairs.

The second mentioned application teaches the use of intermediate drive members which are driven by pairs of electromagnets and which in turn drive selector levers capable of engaging with butts on the needle jacks. The vertical dimension of this second prior art needle selector must also be of necessity so great as to cause inconvenience in handling the bobbins in the use of the knitting machine. Moreover, the construction of this known device is very complex, making its manufacture and adjustment difficult.

According to the invention there is provided an electromagnetic needle selector for circular knitting machines, comprising: a knitting cylinder rotatable about an axis extending vertically; a multiplicity of needle jacks mounted to the knitting cylinder for independent vertical displacement relative to the knitting cylinder; fixed frame means adjacent to the knitting cylinder; a plurality of horizontal shafts mounted to the frame means and disposed in parallel spaced relation to one another in a plane parallel to the axis of the knitting cylinder; a plurality of sleeves rotatably fitted one over each fixed shaft; a plurality of selector fingers secured one to each sleeve and all aligned vertically, the selector fingers being capable of selective engagement with the jacks on the knitting cylinder for causing the independent displacement thereof with the bidirectional rotation of the sleeves on the shafts; a plurality of pairs of electromagnet assemblies immovably supported by the frame means in opposed relation to the respective sleeves on the shafts, with each pair of electromagnet assemblies positioned side by side vertically, each of the electromagnet assemblies comprising a magnetic core having a pair of opposite ends, and a coil wound on the magnetic core; a plurality of armatures secured one to each sleeve and disposed one opposite each pair of electromagnet assemblies so as to be alternately attracted by first ends of the magnetic cores, with the consequent bidirectional rotation of the sleeves on the fixed shafts; and means for forming a closed magnetic circuit for each electromagnet assembly in action together with one associated armature when the electromagnet assembly is being energized, said closed magnetic circuit forming moans comprising: a pair of end blocks of magnetic material in contact respectively with the other ends of the cores of each pair of electromagnet assemblies; and a pair of part cylindrical or substantially part cylindrical members of magnetic material each extending around approximately half the circumference of the coil of one electromagnet assembly, each part cylindrical member being coupled at one end to one associated end block and having another end disposed adjacent to one associated armature.

Preferred and/or optional features of the invention are set forth in claims 2 to 8 inclusive.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which Figure 1 is a top plan view, with parts shown broken away for clarity, of an electromagnetic needle selector, Figure 2 is a vertical section, with parts shown in elevation for illustrative convenience, through the needle selector of Figure 1; Figure 3 is an elevation, with parts shown sectioned for clarity, of the needle selector as seen in the direction of the arrows III in Figure 2, the view explaining the arrangements of the electromagnetic assemblies and the selector fingers in particular; Figure 4 is a vertical section through a pair of electromagnet assemblies and other associated parts, which together constitute an embodiment of the invention; Figure 5 is a perspective view of the pair of electromagnet assemblies shown in Figure 4 ; and Figure 6 is a section taken along the line XII-XII of Figure 4.

As illustrated in both Figures 1 and 2, the needle selector 10 comprises an upstanding knitting cylinder 12 mounted on a platform 14, Figure 2, of a circular knitting machine for rotation about its own axis extending vertically (first direction). The knitting cylinder 12 has multiple grooves 16 cut longitudinally in its surface for slidably receiving needle jacks 18 each having a butt 20. The needle jacks 18 are to be selectively moved up and down on the knitting cylinder 12 for actuating the needles (not shown) of the knitting machine in a known manner.

Disposed in the immediate vicinity of the knitting cylinder 12 is a generally rectangular support frame 22 for supporting the various working components, set forth hereafter, of the needle selector 10 which functions to cause selective longitudinal displacement of the needle jacks 18 on the knitting cylinder 12.

Figure 2 indicates that the support frame 22 is fastened at 24 to the platform 14.

As will be seen also from Figure 2, the support frame 22 immovably supports a plurality of, eight in this particular embodiment, shafts 26 which extend horizontally (second direction) in parallel to one another and which are all contained in a vertical plane. A plurality of sleeves 28 are rotatably fitted one over each fixed shaft 26. Each sleeve 28 has rigidly but removably mounted thereto, a tapered selector finger 30 extending toward the knitting cylinder 12 for selective engagement with the butts on of the needle jacks 18 thereon. All the selector fingers 30 are disposed at the midpoints of the sleeves 28 and are thereby aligned vertically. Preferably, the selector fingers 30 should be fabricated from ceramic material for wear resistance.

As illustrated on an enlarged scale in Figures 4 and 5, each selector finger 30 is replaceably supported by a generally U-shaped carrier 32 secured to associated sleeve 28. It will therefore be seen that the selector fingers 30 can pivot up and down with the bidirectional rotation of the associated sleeves 28 on the fixed shafts 26.

Employed for the desired bidirectional rotation of the sleeves 28 are a plurality of, eight in this embodiment, pairs of electromagnet assemblies 34 and 34' immovably supported within the support frame 22.

Each electromagnet assembly 34 and 34' comprises a magnetic core 36 or 36' with a coil 38 and 38' wound thereon. Each pair of electromagnet assemblies 34 and 34' extend horizontally, with one 34 positioned over the other 34', and with their ends held opposite one of the rotatable sleeves 28.

As will be understood by referring again to Figure 3, the eight pairs of electromagnet assemblies 34 and 34' are arranged in two diagonal rows. It will further be noted that every two pairs of such electromagnet assemblies are in vertical alignment, with the four electromagnet assemblies of each vertical series disposed at substantially the same pitch.

Furthermore, the successive vertical series of electromagnet assemblies are vertically displaced at half the pitch from the neighboring series. So arranged, the eight pairs of electromagnet assemblies 34 and 34' lie opposite the right rotatable sleeves 28, respectively, which are disposed with minimal spacings therebetween.

Such an arrangement of the electromagnet assemblies 34 and 34' makes it possible to reduce the vertical dimension of the needle selector 10 to a value remarkably less than if such pairs of electromagnets were arranged in a single vertical or slanting row, as has been the case heretofore.

Each rotary sleeve 28 has an armature 40 of magnetic material rigidly mounted thereto, in such a position thereon that the armature is opposed to one pair of electromagnet assemblies 34 and 34' associated with that particular sleeve. Since the upper four sleeves 28, for example, are respectively associated with the upper diagonal row of pairs of electromagnet assemblies 34 and 34', the armatures 40 are all mounted at different longitudinal positions on these sleeves.

The armatures on the lower four sleeves 28 are mounted in corresponding positions thereon.

Each armature is shown in Figures 1 to 3 as being of unitary construction but in actual fact each armature is divided into a pair of separate parts 40b and 40b' (as shown in Figures 4 to 6) to be attracted respectively by the associated pair of electromagnet assemblies 34 and 34'. Each armature part is L-shaped as seen in side view as in Figure 4, and the pair of armature parts 40b and 40b' are fastened by a rivet 62 or like fastening element to opposite sides of a tongue 64 formed on the rotary sleeve 28 on each shaft 26.

Thus, as each pair of electromagnet assemblies 34 and 34' is alternately excited with current pulses under the control of an electronic control circuit, not shown, the armature will pivot thereby, bidirectionally driving the associated sleeve 28 through a predetermined angle around the fixed shaft 26. Thereupon the selector finger 30 on the sleeve 28 will pivot up and down about the shaft 26.

The invention further features means for forming a closed magnetic circuit for each electromagnet assembly 34 and 34' in action together with one associated armature 40 when it is being energized, in order to assure more reliable operation of the needle selector 10. Such means are generally shown at 46 in Figures 1 and 2 and comprise a pair of end blocks 46b and 46b' of magnetic material in contact with those ends of the cores 36 and 36', respectively, of each pair of electromagnet assemblies 34 and 34' which are oriented away from the knitting cylinder 12. These ends of the cores 36 and 36' have extensions 48 and 48' of reduced diameter extending though bores in the end blocks 46b and 46b'.

As clearly seen in Figures 1 and 2, the means 46 are engaged in four vertical grooves 52 formed in a support plate 54 of nonmagnetic material removably attached to the support frame 22. The core extensions 48 and 48' extend through the support plate 54 and have nuts 55 engaged on their threaded ends protruding from the support plate. Thus the support plate 54 with the eight pairs of electromagnet assemblies 34 and 34' thereon, is readily removable from the support frame 22 as required.

As shown in Figure 4, the extensions 48 and 48' and 48' of the magnetic cores 36 and 36' may be magnetically isolated from the support plate 54 by fitting sleeves 60 and 60' of magnetic material thereover.

Arms 56, shown in Figures 1 to 3, are replaced, according to the present invention, by a pair of part cylindrical members 56b and 56b' of magnetic material. The members 56b and 56b' extend around approximately half the circumferences of the electromagnet assemblies 34 and 34', respectively. The part cylindrical members 56k and 56b' are coupled at one end to the end blocks 46b and 46b1, respectively. The other ends of the members 56b and 56b' are disposed adjacent to the associated armature. A closed magnetic circuit can thus be formed for each electromagnet assembly, as indicated by the arrows in Figure 4, and by dividing each armature into two parts 40k and 40b', it will be seen that two completely independent magnetic circuits are formed for each pair of electromagnet assemblies 34 and 34', so that the latter are more magnetically independent of each other.

The embodiment further features balls 66 and 66' of steel or like magnetic material which are partly embedded in the end faces of the magnetic cores 36 and 36' of each pair of electromagnet assemblies 34 and 34'.

These balls are to make direct contact with the pair of armature parts 40b and 40b', respectively.

The balls 66 and 66' are effective to reduce the production of residual magnetism on the armature parts 40b and 40b' as well as the generation of noise when the armature parts are attracted. As an additional advantage, the armature parts 40b and 40b' will readily move out of contact with the balls 66 and 66' upon deenergization of the coils 38 and 38', even if, as is frequently the case with knitting machines, the electromagnets and armatures are smeared with lubricating oil.

OPERATION In the operation of the needle selector 10 constructed as in the foregoing, the knitting cylinder 12 with the needle jacks 18 thereon will rotate at high speed for the production of the desired knitted fabric.

During such rotation of the knitting cylinder 12 the eight pairs of electromagnet assemblies 34 and 34' are selectively energized with current pulses as dictated by a pattern signal produced by a preprogrammed electronic control device (not shown). Each armature will have its two parts 40k and 40b' alternately attracted by the associated pair of electromagnet assemblies 34 and 34'.

When the part 40b of the armature is attracted by the core 36, for example, the other part 40b' will be repelled by the core 36'.

When the armatures are so activated by the associated pairs of electromagnet assemblies 34 and 34' with the consequent rotation of the corresponding sleeves 28 on the fixed shafts 26, the selector fingers 30 on these sleeves will act selectively on the butts 20 of the needle jacks 18 thereby creating the desired pattern on the fabric being knitted.

It is to be appreciated that each electromagnet assembly 34 or 34' on being energized, forms a closed magnetic circuit in combination with the armature part 40b or 40b', end block 46b or 46b', and part cylindrical member 56b and 56b'. The closed magnetic circuits serve the dual purpose of augmenting the forces exerted by each pair of electromagnet assemblies 34 and 34' on the associated armature and of preventing mutual magnetic interference between the electromagnet assemblies.

Also, it is an advantage that, being fabricated from ceramic material, the selector fingers 30 will not suffer any rapid wear despite their frequent forced contacts with the butts 20 of the needle jacks 18.

Claims (9)

1. CIJAIHS 1. An electromagnetic needle selector for circular knitting machines, comprising: a knitting cylinder rotatable about an axis extending vertically; a multiplicity of needle jacks mounted to the knitting cylinder for independent vertical displacement relative to the knitting cylinder; fixed frame means adjacent to the knitting cylinder; a plurality of horizontal shafts mounted to the frame means and disposed in parallel spaced relation to one another in a plane parallel to the axis of the knitting cylinder; a plurality of sleeves rotatably fitted one over each fixed shaft; a plurality of selector fingers secured one to each sleeve and all aligned vertically, the selector fingers being capable of selective engagement with the jacks on the knitting cylinder for causing the independent displacement thereof with the bidirectional rotation of the sleeves on the shafts; a plurality of pairs of electromagnet assemblies immovably supported by the frame means in opposed relation to the respective sleeves on the shafts, with each pair of electromagnet assemblies positioned side by side vertically, each of the electromagnet assemblies comprising a magnetic core having a pair of opposite ends, and a coil wound on the magnetic core; a plurality of armatures secured one to each sleeve and disposed one opposite each pair of electromagnet assemblies so as to be alternately attracted by first ends of the magnetic cores, with the consequent bidirectional rotation of the sleeves on the fixed shafts; and means for forming a closed magnetic circuit for each electromagnet assembly in action together with one associated armature when the electromagnet assembly is being energized, said closed magnetic circuit forming means comprising: a pair of end blocks of magnetic material in contact respectively with the other ends of the cores of each pair of electromagnet assemblies; and a pair of part cylindrical or substantially part cylindrical members of magnetic material each extending around approximately half the circumference of the coil of one electromagnet assembly, each part cylindrical member being coupled at one end to one associated end block and having another end disposed adjacent to one associated armature.
2. 2. The electromagnetic needle selector of claim 1, wherein each electromagnet assembly has a ball of magnetic material embedded in the magnetic core thereof for direct contact with one associated armature.
3. 3. The electromagnetic needle selector of claim 2, wherein the balls are of steel.
4. 4. The electromagnetic needle selector of any one of claims 1 to 3, wherein every two pairs of electromagnet assemblies are aligned vertically.
5. 5. The electromagnetic needle selector of claim 4, wherein each series of four electromagnet assemblies aligned vertically are disposed with substantially the same pitch, and wherein each series of electromagnet assemblies are vertically displaced by half the pitch from the neighboring series of electromagnet assemblies.
6. 6. The electromagnetic needle selector of any one of claims 1 to 5, wherein the selector fingers are of ceramic material.
7. 7. The electromagnetic needle selector of any one of claims 1 to 6, wherein the selector fingers are removably mounted to the sleeves.
8. 8. The electromagnetic needle selector of any one of claims 1 to 7, wherein each armature is divided into a pair of separate parts for co-operating, respectively, with an associated pair of electromagnet assemblies.
9. 9. An electromagnetic needle selector substantially as hereinbefore described with reference to the accompanying drawings.