Description:
BACKGROUND OF THE INVENTION
This invention relates to devices for the selection of the needles or knitting accessories of circular knitting machines.
The invention more particularly concerns circular knitting machines provided with independantly movable needles and in which selection is effected by the action of magnetic means on oscillating elements associated with the needles or other accessories to be controlled.
Practical examples of these types of devices, have been known for some time. Such known devices are applicable to circular knitting machines having several knitting stations to which can be associated magnetic selection members which receive excitation impulses provided by reading a given program of information in synchronism with operation of the machine. These magnetic members act directly on oscillating elements associated with the needles, or indirectly by actuation of the mobile parts of pattern wheels, during the rotation of the latter.
In certain known devices, upstream of each selection station, oscillating elements or needle jacks associated with the needles, and comprising an actuating butt, are urged by a cam which pivots them so that their actuating butt comes within the range of a raising cam.
These elements are then submitted to the action of a selectively excited electro-magnetic which, directly or through associated mechanical members, causes pivoting, in the opposite sense to that mentioned above, of the selected members the actuating butts of which, by withdrawal into their guide grooves, are removed from the range of the raising cam. The elements of which the actuating butt is thus withdrawn are hence located in a rest position in which the associated needles are not influenced.
In other types, the butts of the needle jacks are placed within the reach of a raising cam by the permanent urging of individual springs located behind the needle jacks at the bottom of their guide grooves.
INDEPENDANT IS EFFECTED BY MEANS OF OTHER INDEPENDANT INDIVIDUAL SPRINGS LOCATED OUTSIDE THE NEEDLE BED AND WHICH, WHEN THEY ARE NOT HELD BY A SELECTIVELY EXCITED ELECTRO-MAGNET, EACH HAVE A FREE END PROTRUDING BEYOND THE POINT OF A SWITCHING AND CONTROL CAM WHICH ENSURES THAT THEY ARE PLACED INTO CONTACT WITH THE CORRESPONDING NEEDLE JACKS AGAINST THE ACTION OF THE INDIVIDUAL URGING SPRINGS, THE RESPECTIVE BUTTS BEING WITHDRAWN IN THEIR GROOVES AWAY FROM THE RAISING CAM.
Finally, in certain devices, the actuating butts of the oscillating needle jacks are selectively brought, from their rest position, into a position in which they operatively cooperate with a raising cam by the attraction of a selectively excited electro-magnet or by several electro-magnets selectively actuated in succession.
BRIEF SUMMARY OF THE INVENTION
It is an object of the invention to provide a selection device of the above-mentioned type in which oscillating elements are subjected to the action of magnetic selection means, each non-selected element being returned to an inoperative position by means of an elastically deformable part, such as a tongue, integral with the body of the element.
The invention is particularly applicable to a circular knitting machine comprising a plurality of needles or knitting accessories relatively movable past at least one selecting station, wherein each needle or accessory is independantly slidable in a guide groove between a working position and a rest position and is associated with an element movable between an operative position and an inoperative position, and wherein each selecting station comprises magnetic selection means for controlling movement of the elements and means downstream of the selection means for causing the needles or accessories associated with elements in the operative position to adopt the working position whilst allowing the needles or accessories associated with elements in the inoperative position to adopt the rest position. The invention previews the improvement in which each element comprises an elastically deformable part and means are provided for causing the elements to be delivered to the selection means in the operative position with the deformable parts deformed, the selection means being able to selectively hold the elements in the operative position against elastic urging of the deformed parts, and the non-selected elements being moved to the inoperative position by elastic urging of the deformed parts.
Preferably, when the selected elements are slightly downstream of the selection means, their deformed parts are able to elastically return to the undeformed state without moving the selected elements from the operative position.
The movable elements can be oscillable needle jacks each having an actuating butt to which the magnetic field of the selection means can be applied.
The accompanying drawings shown, by way of example, an embodiment of the device according to the invention, as well as variants.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
FIG. 1 is a side view, partly in radial cross-section, of part of a circular knitting machine with a rotating needle bed having several selection stations and provided with oscillating needle jacks, one of which is shown in the selected or operative position in which it holds an associated needle in a raised working position.
FIGS. 2 and 3 are views similar to FIG. 1, but in which the cross-section passes through the plane of a selection station of the device, an oscillating needle jack being shown held in a selected or operative position in FIG. 2 and freed in a rest or inoperative position in FIG. 3.
FIG. 4 is a schematic plan view of a part of the same knitting machine.
FIGS. 5 and 6 are views similar to FIG. 4 showing two modifications.
FIG. 7 is a view similar to FIG. 2 of a third modification.
FIGS. 8 and 9 are views similar to FIG. 7 but in two different operating positions.
FIG. 10 is a schematic view similar to FIG. 6 corresponding to the modification of FIGS. 7, 8 and 9.
FIG. 11 is a schematic perspective view of a part of the knitting machine according to the modification of FIG. 7 through 10.
DETAILED DESCRIPTION
In FIGS. 1 to 4 of the drawings, a rotating cylinder 1 of the illustrated knitting machine is supported by a driving ring 2 and comprises at its periphery a series of grooves 3 parallel to the axis of the cylinder and in which independant needles 4 each provided with an actuating butt 5 can slide. Each butt can cooperate with the usual control cams 6 fixed on the cam-box 7 which is mounted on the principal stationnary plate 8 fixed to the frame of the machine.
The needles 4 can be selectively slid in their grooves between a lowered rest position (FIGS. 2 and 3) and a raised working position (FIG. 1) by means of individual oscillable needle jacks 9 each comprising a projecting actuating butt 10. Each needle jack is able to pivot about an end 9' so that in an operative position the actuating butt 10 engages with a raising cam 11, also fixed to the stationary cam-box 7, and in an inoperative position the butt 10 is removed from cam 11.
Between the end 9' and the actuating butt 10, each needle jack comprises a part 12 capable of being elastically deformed in relation to the main body of the jack. In the illustrated example this part is in the form of an elastic tongue, which is manufactured integrally with the needle jack.
Upstream of each selection station (see FIG. 4), all of the needle jacks are urged by a setting cam 13 which acts on their lower end so that the butts are urged to the operative position in which they engage the raising cam 11.
To counteract this action, a cam 14 fixed to the cam-box 7 exerts a thrust on the elastically deformable tongues 12, which are thus deformed. The actuating butts 10 of the needle jacks thus move through the magnetic field of an electro-magnet 15 mounted on a support 16 fixed to the stationary cam-box. The needle jacks are made of a suitable magnetic material so that they are subjected to a magnetic attraction greater than the mechanical reaction provided by each tongue 12 and which tends to urge the needle jacks to the inoperative position. The electro-magnet is selectively excited by means of impulses delivered as a function of an operating program, not shown.
As can be remarked on FIG. 4, the setting cam 13 ceases to exert its action on the lower end of the needle jacks as soon as the actuation butts are submitted to the selective attraction of the pole 17 of the electro-magnet 15 (FIGS. 2 and 3).
During the passage of the needle jacks, solely those for which the actuation butts are submitted to the selectively controlled magnetic field of the electro-magnet 15 are held in operative position on the cam 11. These jacks, shown in FIG. 2 and indicated by A in FIG. 4, subsequently ensure actuation of the corresponding needles. Conversely, the needle jacks of which the actuation butt has not been submitted to the influence of the electro-magnet 15 (shown in FIG. 3 and indicated by B in FIG. 4) pivot towards their inoperative position in which their butts are separated from cam 11 because they are no longer held by the setting cam 13 and because of the unbending of the deformed parts 12, which by pressing against the thrust cam 14 cause the jacks return to their initial form prior to the deformation.
In the variant shown in FIG. 5, a magnet 21, constituting magnetic means for maintaining selection, is fixed to the stationary cam-box 7 adjacent to and upstream of the selection electro-magnet 15. Magnet 21 has substantially the same attractive force as electro-magnet 15 and exerts a permanent influence solely on the butts of the needle jacks A selected by the electro-magnet 15. The needle jacks B not selected by the electro-magnet 15 are returned to their inoperative position by the action of their elastic tongues 12 before they reach electro-magnet 21; the effect of the field of electro-magnet 21 on the non-selected needle jacks B is therefore negligible in view of the separation of the actuation butts thereof from magnet 21. The two magnets 15 and 21 are separated by a non-magnetic material 23 to avoid interference between the two respective magnetic fields. During operation, the needle jacks A selected by means of the electro-magnet 15 thus pass from the field of electro-magnet 15 to that of the adjacent magnet 21 without a risk of pivoting back into their inoperative position under the effect of unbending of their elastic tongues 12.
Magnet 21 is preferably a permanently maintained electro-magnet. Whilst electro-magnet 21 exerts an influence on an actuation butt 10, the thrust cam 14 ceases action on the corresponding elastically deformable tongue 12, which returns to its undeformed position without causing displacement of the needle jack in question so that the actuation butt 10 remains in operative position on the raising cam 11.
The variant shown in FIG. 6 enables improvement of the delivery of the needle jacks to the selection means. To this end, a setting cam 13a acts on the lower end of the needle jacks and puts their actuating butts 10 into the operative position as at C. These butts are thus submitted to the attractive magnetic field of a lead-in magnet 25 located upstream of selection electro-magnet 15a. Magnet 25 is located adjacent the selection electro-magnet 15a so that it bridges a gap between the downstream end 13b of the setting cam 13a and the attacking adge D of the selection magnet 15a. The excitation of the selection electro-magnet 15a is once more controlled by impulses as a function of a program, not shown. The electro-magnet 15a and the magnet 25 are both fixed to the stationary cam-box; the neighboring edges of the polar surfaces of these two magnets are separated by a non-magnetic material to avoid interference between the two magnetic fields. Consequently, a needle jack can pass from the magnet 25 to the selection electro-magnet 15a, when the latter is excited, without being pushed back to its inoperative position by action of the deformed tongue 12 submitted to the thrust of the cam 14.
The magnetic field of the magnet 25 is sufficient to overcome the force supplied by each elastic part 12, deformed against the thrust cam 14, and holds the needle jacks in operative position. The relative disposition of the downstream end 13b of the setting cam 13a, the lead-in magnet 25, and the selection electro-magnet 15a is such that the setting cam 13a ceases to act on the lower part of the needle jacks 9 before the actuation butts 10 of these jacks are subjected to the action of the selection electro-magnet 15a, the needle jacks being held in operative position by the magnet 25.
Magnet 25 is preferably a permanently fed electro-magnet and, during passing by of the needle jacks in front of a selecting station, all of the butts 10 are attracted and held by this permanent electro-magnet 25.
Certain butts 10 are submitted to the selective attraction of the electro-magnet 15a. The non-attracted butts E are automatically displaced towards their inoperative position so as not to engage with the lifting cam 11. This displacement is caused by unbending of the deformed parts 12, which press against the thrust cam 14 and cause pivoting of the corresponding needle jack towards the rotating cylinder 1.
A second permanently maintained magnet 21a, constituting magnetic selection holding means, is mounted on the stationary cam-box downstream of the selection magnet 15a.
Magnet 21a holds the butts 10 of the needle jacks F selected by the magnet 15a in their operative position on the cam 11. The downstream edge of magnet 21a extends further downstream than the downstream edge G of the thrust cam 14 so that the tongues 12 return to their original undeformed state without causing pivoting of the selected needle jacks, as is seen for the needle jack indicated by H.
By means of this particular arrangement, it is no longer necessary to establish a precise positional relationship between the end 13b of the setting cam 13a and the selection electro-magnet 15a, all of the actuating butts 10 being submitted to the magnetic field of the magnet 25 and subsequently being safely and precisely delivered to the selectively operated magnetic field of the electro-magnet 15a.
Additionally, this arrangement enables an increase in the rate of selection of the device with a maximum reliability and safety.
The third variant, shown in FIGS. 7, 8 and 9, aims to provide a maximal reduction of the required attractive power for the magnetic lead-in means. Consequently the power consumption of the electro-magnets can be reduced and the device can have a smaller bulk whilst ensuring the optimum operating conditions with a great reliability in delivery of the oscillating elements to the magnetic selecting means.
The operation of this variant will be described with reference to FIGS. 10 and 11.
Upstream of each selecting station and during their displacement in relation to the stationary cam-box, all of the needle jacks 9a are submitted to the action of a setting cam 13b, fixed to the cam-box, which acts on their lower ends so that their actuating butts 10 are placed in the operative position.
The actuating butts 10 are thus submitted to the influence of magnetic lead-in means 25a fixed to the cam-box by means of a bracket 36 so that the butts of the needle jacks are held in their operative position when the setting cam 13c ceases its action.
During holding of the butts solely by the magnet 25a, a cam 14a, fixed to the cam-box, exerts a thrust on the tongues 12 as indicated by 9b. As has been previously described, when the needle jacks reach the position indicated by 9c, their actuating butts are then selectively subjected to the magnetic field of an electro-magnet 15a, the tongues 12 being in their deformed state.
The needles jacks such as 9d of which the actuating butt is not held by the magnetic field of the selecting electro-magnet 15a pivot under the action of unbending of their tongue 12 which presses against the thrust cam 14a to return to their undeformed state, the corresponding actuating butts thus being displaced towards their inoperative position away from the raising cam 11.
The butts of the selected needle jacks 9e remain in the operative position in which they are temporarily held by attraction of the holding magnet 21a during cessation of the action of the thrust cam 14a; the deformed tongues 12 can thus return to their initial undeformed state without causing the selected needle jacks to pivot.
Once the selected needle jacks 9f have passed by the holding magnet 21a, they are moved to a raised position by the raising cam 11 so that they slide the associated needles up into the working position.
The non-selected needle jacks 9g have their butts 10 removed from the raising cam 11 so that the corresponding needles remain in the lower rest position.
The magnet 25a constituting the magnetic lead-in means, as well as the holding magnet 21a, can be permanent magnets, but are preferably permanently supplied electro-magnets.
By means of this particular arrangement, it is possible to hold the oscillating elements in operative position with a minimum of power and maximum efficiency. The oscillating elements are nevertheless precisely and reliably delivered to the magnetic field of the selecting electro-magnet.
In this variant, each oscillating needle jack 9a also has a protruding part 3k on its rear edge. When the needle jacks are located in the lower inoperative position, the parts 3k are housed in a recess 3m in the guide groove 3.
As soon as the butt 10 of a selected oscillating element engages on the slope 11a of the raising cam 11, the protruding part 3k contacts the bottom of the non-recessed part of the groove 3 (FIG. 9) thus preventing any unwanted radial displacement of the butts of the needle jacks from the operative position towards the inoperative position.
This particular arrangement enables the needle jacks 9 in operative position to manouvre radially, for example under the elastic urging of the deformed elastic tongues 12, prior to raising the associated needles to the working position whilst enabling the needle jacks to be firmly held when the associated needles are raised, without having to rely upon a braking of the needle jacks, as is normally used but which does not allow the jacks the same freedom of manouvre.
Whilst in known devices the needle jacks are moved into inoperative position by means of a cam, or magnetically or by means of separate springs, in the described device according to the invention the needle jacks are brought to the inoperative position by means of the elastic tongues integral with the needle jacks.