GB2043713A - Needle selecting device for knitting machines - Google Patents

Abstract

In a knitting machine there is provided at least one needle selecting device comprising a plurality of superimposed levers (13) and a corresponding number of electromagnets (18). There is further provided a tilt-out cam (12) for operating on tiltable jacks, during relative movement between the jacks and cam (12). The levers (13) have a profile such that the pattern butts (7a) of the tilted out jacks first displace the respective lever (13) toward the respective electromagnet (18). When the latter is energized the lever (13) is attracted thereby and the same jack or a preceding corresponding jack is left tilted out to cause the corresponding needle to knit. When the electromagnet (18) is not energized the respective lever (13) is returned to its starting position under elastic means (15) and the jack is tilted in, so that the corresponding needle does not knit. <IMAGE>

Description

SPECIFICATION Needle selecting device for knitting machines This invention relates to a needle selecting device for knitting machines, in particular circular knitting machines.

In general, for selecting the needles in circular knitting machines, there are provided selecting drums or stacked selecting disks, which have a plurality of pheripheral pegs or teeth arranged in accordance with a given pattern and adapted for interfering, during the rotation of the needle cylinder and/or of the drums or disks, with respective butts of jacks positioned under the needles. As a peg or tooth interferes with a butt, it urges the respective jack into its own groove in the needle cylinder to a position whereat it will not be subjected to the action of a successive raising cam, thereby it will not drive its corresponding needle to form a stitch.The opposite is true when there is no peg ortooth atthe height of the butt of a given jack, thereby the latter is sub jetted to no movement towards the groove inside and, therefore, is caused to climb said cam to bring the overlying needle into operation.

This same principle applies both to rotating cylinder(s) circular machines and to stationary cylinder machines with rotable cams, there being provided in either case a relative rolling movement between the cylinder and the drums or disks.

These selection devices, however, are not devoid of drawbacks and disadvantages. They are comparatively bulky, must be actuated exactly timed with the needle cylinder, i.e. they are called upon to provide a perfect rolling movement without slippage, require special care in arranging the pegs or teeth, the incorrect arrangement of but one peg or tooth being enough to result in a defective product. In this case, by the way, the tracing of the incorrectly arranged peg or tooth is specially difficult. Another disadvantage is that, whenever it is desired to change the product pattern, and accordingly the selection sequence, it becomes necessary to install a new drum or new set of toothed disks.

This invention sets out to overcome such drawbacks and disadvantages, by providing a selecting device for knitting machines, which while having a limited bulk, has no timing problems, requires no accurate arrangement of the pegs orteeth, and is also readily adaptable for a large variety of patterns without replacing any mechanical components.

According to one aspect of this invention, there is provided a needle selecting device for knitting machines, in particular circular knitting machines, of the type comprising tiltable jacks each having one pattern butt and each being tiltable between a position inside and a position outside with respect to the respective groove in the needle bed in which they are accomodated, the butts being arranged at several levels, the device comprising a plurality of overlaid selecting levers for interfering with the butts of the jacks at a respective level, a tilt-out cam positioned adjacent said selecting levers to bring the butts of all the jacks to said outside position, said levers having each, on their side facing the needle bed, a profile such that when one butt is urged outwards by said tilt-out cam the respective lever is moved away from the needle bed to an inoperative position, and a plurality of electromagnets, each whereof is associated with a respective one of said levers and actuated in accordance with a knitting program to selectively retain the respective lever in said inoperative position or release the respective lever to an operative position whereat said lever urges towards said inside position a butt which has moved past the location of said tilt-out cam, the levers being moved to said operative position by respective elastic means.

Advantageously, in a device according to the invention, selection drums or disks formed with pegs or teeth are no longer provided, and only simple levers are employed wich are operated at first mechanically only by the butts themselves, such as to reach a position whereat they can be drawn and held away from the needle bed or cylinder when the respective electromagnet is activated. As the butt moves past the lever tilt-out cam, the lever will urge by elastic action said butt or another butt towards the inside of the groove when the respective electromagnet is not energized or leave it outside thereof when the respective electromagnet is energized.

Advantageously, the first rotation phase of the lever enables the size and power of the electromagnets to be reduced, which are no longer expected to perform the entire lever withdrawal work but only the withdrawal of the lever as already positioned very close to the electromagnets and to hold said lever thus withdrawn. The elastic means returning the lever towards the needle bed or cylinder, which work against the electromagnets, may be provided with a moderate elastic force, since they only serve to urge the butts into the grooves of the needle bed or cylinder.

Moreover, in this device the selection control is reduced to a simple selective energization of the electromagnets, thereby the selection is electronically controllable, e.g. by means of perforated cards, and lends itself to be easily and quickly modified every time that the product pattern is to be changed.

The overall dimensions of the device are, moreover, quite small.

Further details and advantages of the invention will be more clearly apparent from the following detailed description of some preferred embodiments of the invention, given herein by way of example only and shown in the accompanying drawings where: Figure 1 is a partial axial section through a circular knitting machine provided with a device according to this invention, the machine being in this example a large diameter cylinder and dial machine; Figure 2 is a diagram of the jacks and needles arrangement; Figure 3 shows the needle raising cams and the jacks, as well as the relative arrangement of the jack tilt-out cam; Figure 4 is a top view, to an enlarged scale, of a device according to the invention in the rest condition thereof; Figures 5,6 and 7 show the same device as Figure 4 at various operating stages; and Figures 8, 9 and 10 show some variations of the selecting levers of a device according to this invention.

With reference initially to Figure 1,the numeral 1 designates the needle bed or cylinder and 2 desig nates the needle dial of a large diameter circular knitting machine having rotary cylinder and dial. The cylinder 1 is carried rotatably in a stationary portion 3 of the machine and is rotated through a gear 4. In vertical grooves 5 of the cylinder 1, there are slidable needles 6 and underlying jacks 7 each provided with a pattern butt 7a and a main butt 7b. The jacks 7 are retained with their top portions inside the grooves 5, e.g. by means of annular springs in a manner known per se, but are allowed to tilt or rock with their butts 7a partly towards the outside of the grooves 5. In the grooves 8 of the dial 2 needles 9 are slidable in a radial direction.

To the stationary portion 3 of the machine, there is attached an annular plate 10 which carries selecting devices 11, specifically one selecting device 11 for each yarn feed in the machine.

This device 11 comprises a tilt-out cam 12, preferably of substantially triangular shape, which is attached to the plate 10 at the lower or bottom portion of the cylinder 1 and provided with an inclined edge 12a which is adapted to interfere, during the rotation of the cylinder 1, with the inside lower end portion of all the jacks 7 to urge the latterto a position whereat their butts 7a protrude out of the grooves 5. The inclined edge 12a extends, therefore, radially outwards considering the direction of movement of the jacks 7 and cylinder 1, as indicated by the arrow F.

On the opposite side to cam 12 with respect to the path of the jacks 7, the device 11 comprises a plurality of selecting levers 13 overlying one another and freely and independently hinged to a vertical support in form of a pin 14 attached to the plate 10. The levers 13 extend substantially tangentially to the needle cylinder 1. To the end of each lever 13 lying remotely, with respect to the pin 14, from the tilt-out cam 12, there is attached one end of a spring 15, or another elastic means, the other end whereof is securged to a vertical shank 16, affixed to the plate 10.

Each spring 15 tends to hold the free end of its respective lever 13 in a position very close to the needle cylinder 1 or in contact therewith. Advantageously, a stop 17 may be provided for the levers 13, in order to prevent them from rubbing against the cylinder 1.

The profile of the edge of the levers 13 facing the needle cylinder 1 has advantageously a portion 13a sloping towards the needle cylinder 1 in the same direction as the direction of movement of the jacks 7, the end of said sloping portion 13a being substantially located in front of the outermost point 1 2b of the cam 12 and at a distance therefrom which is smaller than the radial dimension of the jack 7 when added to that of the butt 7a, when the levers 13 are in their operative positions where, underthe action of the respective springs 15, they are practically contacting the needle cylinder 1.

In the first embodiment shown in Figures 4 to 7, the sloping portion 13a is followed by a recessed portion 13b of the levers 13, thereby a small triangu lay tooth 13c is defined on the levers 13, substantially in front of the outermost point of tilt-out cam 12. The recessed portion 13b is followed, in the direction of movement of the jacks 7, by a further inclined or sloping portion 13d preferably steeper than the portion 13a, which extends with a portion 13e having a constant width up to the free end of the levers 13.

The distance between the point of the sloping portion 13d which is set closerto the needle cylinder 1 and the apex of the small tooth 13c is, in the longitudinal direction of the levers 13, slightly greater than the circumferential distance between two adjacent butts 7a located on the same level. In any case the further sloping portion 13d is arranged further away from the outermost point 12b than the tooth 13c. On the side of the levers 13 opposite to the side facing the cam 12, there is arranged a plurality of overlaid or stacked electromagnets 18, advantageously accomodated in a single block 19. An electromagnet 18 is respectively associated with each lever 13.The polar ends of the electromagnets 18 are at a distance from the needle cylinder 1 such as to enable the levers 13 to be shifted through a slightly larger angle than the angle whereat the small tooth 13c engages a butt 7a as tilted out by the tilt-out cam 12. In other words, each lever 13 can be shifted angu marly to a position where one longitudinal side of the free end is substantially in contact with the needle cylinder 1 and to a position where said free end is away from the needle cylinder and the opposite longitudinal side of said free end is located in the proximity of the polar end of the respective electromagnet 18.The power supply wires to the electromagnets 18 are indicated at 20 and are connected to a central electronic control, not shown, which supplies a voltage to such wires in a selective fashion, in accordance with the work program related to the pattern to be obtained on the fabric, as will be apparent hereinafter.

In discussing the operation of a device according to the invention, reference will be made in particular to Figures 4 to 7, which show, for clarity, single lever 13 and single electromagnet 18. These figures further show, in darker lines, the butts (with their respective portions of the jack section) that are located at the same level as the lever 13, shown in those same figures. In lighter lines are instead shown all ofthe remaining butts and jacks located at other levels and intervening between the butts shown in darker lines.

The preferred arrangement of the butts on various different levels along the periphery of the cylinder is shown in Figure 2.

It is assumed that the lever 13 is at the end of a selection operation, as indicated in Figure 4. The butt 7a' which is arriving in the direction of the arrow F is initially pushed, by the tilt-out cam 12, out of its own groove 5 to an increasing outward position, until is contacts the sloping portion 13a and produces progressively a rotation of the lever 13 against the spring 15 (Figure 5). All the other butts 7a are also subjected to the action of the cam 12, but being located at a different level, have no action on the lever 13 shown, but only on the corresponding levers not shown in Figures 4-7.

As the butt 7a' moves past the outer apex of the inclined or sloping portion 13a, there occurs one of two things. If in the meantime the electromagnet 18 has not been energized, the lever 13, under the action of the spring 15, is returned to the starting or operative position of Figure 4, since no engagement is established with the butt 7a', which is now at the recessed portion 136.to Thus, the lever 13 pushes into the groove the butt 7a" which precedes the butt 7a' on the same level (Figure 6). The jack having the butt 7a", therefore, does not climb the cam 21 (Figure 3) with its butt 7b, and remains with its butt 7b in a lower track A and does not move the respective needle 6 into loop-forming operation.

If on the contrary, the electromagnet 18 has been energized, then the lever 13 is pulled thereby and held pulled in an inoperative position, and the butt 7a" is not influenced by the lever and remains on the outside as remains the butt 7a' (Figure 7). The jack which carries the butt 7a" climbs then, along with its main butt 7b, the cam 21 along a track B and brings the respective needle 6 to form a loop.

It will be appreciated that by synchronizing the energization of the electromagnets 18 with the position of the butts 7a in their movement in the direction of the arrow F, the desired selection can be accomplished.

The butt 7a ', which had previously acted upon the lever 13, continues its movement until it reaches the position previously occupied by the butt 7a". Atthis point, selection will occur of the butt 7a' as well, after a further butt 7a"' has rotated the lever 13 outwards underthe influence of the cam 12.

In the embodiment shown, it is contemplated, in essence, that a butt will mechanically bring the lever 13 to a position substantially proximate the polar ends of an electromagnet 18, and that after completing its mechanical action on the lever, it will enable selection of the butt which is leading on the same level. Thus, it is not necessary for each electromagnet 18, to perform all the work involved in drawing the respective lever 13, but just the final drawing of the lever and retention thereof, and this only when a given jack7 is not to be pushed into its own groove 5. It follows that the electromagnetics can be reduced to a very small size, thereby reducing their space requirements.

Figure 8 shows a lever 13', wherein the recessed portion 13b' has a substantially smaller length than the portion 13b of the lever 13 in Figures 4-7 and than the distance between two adjacent pattern butts 7a located at the same level. In this instance, the actuation of the lever 13' and the retention or non-retention thereof by an electromagnet 18 is accomplished similarly to the preceding embodiment, with the difference that the return movement of the lever 13' to its starting position no longer urges the preceding butt 7a" into the cylinder interior, but rather that same butt 7a' which immediately before had shifted the lever 13' outwardly.

Figure 9 shows a lever 13", wherein the recessed portion 13b or 13b' is completely eliminated. In other words, the sloping portion 13a", the closest point whereof to the needle cylinder 1 is located substantially in front of the outermost point of the tilt-out cam 12, is followed by a portion 13e" of the lever 13" which has constant width. In this instance, the operation will be similar to the preceding embodiment operation, excepting that the release of the lever involves the striking action for the insertion of the butt7a' into the groove 5, whereas in the previously considered embodiments the butt 7a" or 7a' was at least partly guided progressively or led into the groove 5 by the sloping portion 13d of the lever 13 or 13' upon release thereof by the electromagnet 18.

Figure 10 shows a lever 13"', wherein the profile of the edge thereof facing the needle cylinder 1 is identical to the profile of the lever 13' in Figure 8, but wherein the lever is an angled lever of substantially V-like shape and the electromagnets act upon the outermost portion or section of the lever 13"'. One arm or leg of the "V" is substantially tangent to the needle cylinder 1, while the other arm or leg can be drawn by the respective eletromagnet. The spring 15 is located here inside the V-like space defined bythe angled lever 13"'.This embodiment has the advantage that it provides better protection for the space between the levers 13"' and the respective electromagnets against any fragments of material which might come off the cylinder and locate themselves between the levers and electromagnets thereby preventing the levers from tilting fully outwards, which results in the butts which actuate such a tilt-out movement braking undertheaction of the cam 12.

Advantageously, the device just described can be easily adapted for a large variety of patterns, without changing any mechanical parts thereof, but by just modifying the sequence of the controls to the electromagnets, i.e. by varying the electronic selection control. It should be further noted that the instant device is quite compact, while any difficulties in timing the cylinder to the selection device have been successfully removed.

A device according to this invention is equally useful for fixed cylinder machines, in which case the device would be mounted on the rotary portion of the machine which carries the cams and revolves around the needle cylinder. The device can also be applied to single-cylinder and double-cylinder knitting machines, as well as to flat bed knitting machines, in particular by arranging the device onto the carriage, such as to have a first set of levers and electromagnets for selecting the needles of the needle bed in one direction of the carriage reciprocation and a second set of levers and electromagnets in the opposite direction, each set being made inoperative while the other set is operating.

Several modifications and variations are, of course, possible in addition to the ones described hereinabove, without departing from the scope of this invention.

Claims (11)

1. A needle selecting device for knitting machines, in particular circular knitting machines, of the type comprising tiltable jacks each having one pattern butt and each being tiltable between a position inside and a position outside with respect to the respective groove in the needle bed in which they are accomodated, the butts being arranged at sev eral levels, the device comprising a plurality of overlaid selecting levers for interfering with the butts of the jacks at a respective level, a tilt-out cam positioned adjacent said selecting levers to bring the butts of all the jacks to said outside position, said levers having each, on their side facing the needle bed, a profile such that when one butt is urged outwards by said tilt-out cam the respective lever is moved away from the needle bed to an inoperative position, and a plurality of electromagnets, each whereof is associated with a respective one of said levers and actuated in accordance with a knitting program to selectively retain the respective lever in said inoperative position or release the respective lever to an operative position whereat said lever urges toward said inside position a butt which has moved past the location of said tilt-out cam, the levers being moved to said operative position by respective elastic means.

2. A device according to Claim 1, wherein each said lever extends substantially tangentially to the needle bed and can be shifted angularly substantially between a position whereat one longitudinal side of one end of said levers substantially contacts the needle bed and a position whereat said end is located away from the needle bed and the opposite longitudinal side of said end is located in the proximity of the polar ends of a respective one of said electromagnets.

3. A device according to either Claim 1 or 2, wherein the profile of each said lever facing the needle bed has a sloping portion defining a substantially triangular tooth substantially in front of the outermost point of said tilt-out cam.

4. A device according to Claim 3, wherein each said lever is also provided with a further portion sloping toward the needle bed in the relative direction of movement of the jacks with respect to said levers, said further sloping portion being provided downstream, in the direction of said relative movement, of said tooth and separated therefrom by a recessed portion of said levers.

5. A device according to Claim 4, wherein the distance between the point on said further sloping portion located closest to the needle bed and the apex of said tooth only slightly exceeds the distance between two adjacent butts of one level.

6. A device according to Claim 4, wherein the length of said recessed portion is appreciably shor terthanthe distance between two adjacent butts of one level.

7. A device according to either Claim 1 or 2, wherein each said lever has a profile facing the needle bed provided with a portion or section sloping toward the needle bed in the direction of relative movement between the jacks and said levers, the point on said sloping portion located closesttothe needle bed being placed substantially in front of the outermost point of said tilt-out cam, said sloping portion being followed by a constant width portion of said levers.

8. A device according to either Claim 1 or 2, wherein each said lever has a substantially V-like configuration, one arm of the "V" being substantially tangent to the needle bed and the other arm being drawable by the respective one of said electromagnets.

9. A device according to any of the preceding claims, wherein said tilt-out cam has a substantially triangular shape.

10. A needle selecting device for knitting machines particularly circular knitting machines substantially as herein described with reference to the accompanying drawings.

11. A knitting machine, comprising at least one needle selecting device as claimed in any one of Claims 1 to 9 above.