GB1564942A - Circular knitting machine - Google Patents

Description

(54) CIRCULAR KNITTING MACHINE (71) We, FRANCESCO LONATI, ETTORE LONATI, FAUSTO LONATI, TIBERIO LONATI, trading under the trading style of COSTRU ZIONI MECCANICHE LONATI di Lonati Francesco e Figli Ettore, Fausto, Tiberio S.n.c., organized and existing under the laws of Italy, of Via S. Polo, 1 1-Brescia-Italy, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a double-cylinder circular knitting machine having cams for opening the latches of the needles being transferred from one needle cylinder to the other.

As known in the art, on transferring a double-hooked needle in a double-cylinder circular knitting machine, e.g. when the needle is required to convert from plain knitting to rib knitting, it is necessary that the needle has its latch in the opened state, such that all appropriate hook of the slider intended to pick up the needle to be transferred is enabled to enter the space enclosed by the needle hook and engage said hook, preparatory to pulling the needle within the respective needle cylinder. At this stage, the slider also effects a swinging movement, projecting for a moment with its end adjacent the hook out of the cylinder groove and then swings back to hook up the needle to be transferred.

If the needle latch is closed, it can happen that, when the slider swings back to hook up the needle, the hook of the slider meets opposition by the closed latch, distorts the latter, and since the slider is urged to swing back by specially provided cams, breaks the latch and is itself damaged.

In order to prevent such occurrences, the cams located upstream of the needle transfer area are shaped to bring the sliders and needles close to each other at the precise point where the closed latches approach the needle hooks, such that during the subsequent relative movement of the needles and sliders each of the latter first enters with its tip between the corresponding latch and the needle hook, and then gradually opens up the latch.

Such a system, however, requires that all the needles to be transferred be correctly brought to an accurate position of cooperation with the respective sliders, as explained above.

On the machines designed for a more complex operation, e.g. on circular knitting machines provided for "links-Jacquard" knitting, wherein two or three feeds are provided having different color threads and rib knitting is contemplated and various pattern drums are to be pre-arranged, it can even more easily occur, due to a mistake in the presetting of one of the pattern drums, that a needle to be transferred performs a wrong movement, thereby reaching the transfer point with the latch in the non-opened state.

Assuming, for instance, the case of a "links-Jacquard" knitting machine, wherein the needles of the lower needle cylinder not involved in knitting at the feed located after the transfer area (considering the needle direction of movement with respect to the cams) must remain in a "floating" or low position, whereas both the needles which have to knit at that feed and the needles which are to be transferred must follow a higher track.Now, if a needle to be transferred, rather than following the high track is erroneously brought by its slider to follow the "floating" track, then it will be raised anyhow to a transfer position by its respective underlying pattern selecting jack, but will reach the height level suitable for being hooked up by the slider of the other needle cylinder when this slider is swung out of its cylinder groove and thus is unable to open the needle latch, should the latter have stayed closed. In this case, the aforementioned events would occur, i.e. the breaking of the needle and slider as the latter swings back into the groove.

However, the correct arrangement of the pattern drums, that is the correct arrangement on such drums of the various so-called safety teeth or pins, which are operative to direct along the right track the sliders and needles associated therewith, is susceptible of errors that are greater the more compli- cated the knitting is. The absence of even a single tooth or pin arranged to bring a needle to be transferred to a position suitable for the opening of the latch is enough not only to result in a faulty product but also to break the slider and needle, and hence the machine must be stopped, the error on the drum located, the drum reassembled and the slider and needle replaced, thus causing considerable delay and loss of production.

According to the invention there is provided a double-cylinder circular knitting machine having cams for opening the needle latches, sliders facing each other within the two needle cylinders and needles each engaging a respective one of said sliders, control cams for engaging butts of said sliders defining at least a first track for butts of the sliders associated with the needles to be transferred and at least a second track for butts of the sliders associated with the needles not to be transferred, wherein the cams further comprise an auxiliary cam located upstream of the transfer area and shaped to bring the needles associated with all the sliders which have butts guided along said second track to a level of contact with the respective facing sliders of the other needle cylinder, thereby providing a gradual opening of the needle latches by said facing sliders, and a subsequent cam shaped to bring the sliders associated with the needles not selected for the transfer proper back to the level of said second track.

In the above machine, even though the slider of a needle has failed to be correctly brought to the transfer track but stayed by mistake in the "floating" track, i.e. the track termed as the second track hereinabove, it would nevertheless be brought towards the opposite slider so as to ensure the opening of the latch, due to the provision of the auxiliary cam and to the arrangement thereof; before the slider starts to swing toward the outside of its groove. Thus, any breakage during the slider swinging back stage is effectively prevented, even if the slider fails to start along the transfer track proper.Of all the sliders which move along the "floating" track, those associated with the needles to be transferred are then driven by their respective selecting jacks for the transfer proper of the needle, whereas the remaining ones, associated with the needles not to be transferred, are brought by the subsequent cam to the level of the "floating" track wherein they were previously located, since there are no selecting jacks to cause them to effect the transfer.

With the above machine, the opening of the latches of all the needles is thus advantageously provided, including the latches of the needles that are not to be transferred.

Most advantageously, the auxiliary cam may be arranged, either stationary or movable, at the "floating" track level or at a different level to act upon a slider butt different from the one engaged along the "floating" track.

The invention will be further described through the accompanying drawings, which include a preferred, though not exclusive, embodiment thereof, provided by way of example. in the drawings: Fig. 1 shows the cams of a prior art doublecylinder circular knitting machine and illustrates some needle transfer phases from the lower needle cylinder to the upper one, the sliders and needles involved in such a transfer being depicted, for a clearer view, in a plane turned through 90" from the actual one.The sliders that have been hatched are sliders which have been erroneously guided into the "floating" track; Fig. 2 shows the cams of a machine according to the invention, and how the opening of the latch and transfer of a needle associated with a slider moving along the "floating" track are carried out, the needle and slider being represented turned through 90 , and Fig. 3 shows, to an enlarged scale, some phases relating to the opening of a latch prior to the hooking up of a needle by the overlying slider in a machine according to this invention.

Making reference first to Figure 1, a prior art double-cylinder circular knitting machine is considered which includes a cam ring 1 for controlling sliders 2 in the upper needle cylinder and a cam ring 3 for controlling sliders 4 in the lower needle cylinder. The numeral 5 denotes double-hook needles, which are designed for transfer from the lower needle cylinder to the upper one. The needles have at each end a hook Sa and latch Sb. The numeral 6 denotes selecting jacks for the lifting of the sliders 4 to the transfer position, the jacks being controlled in a known manner by selecting levers 7 acting upon patterning butts 8 of the selecting jacks.

The selecting jacks arranged to bring the sliders 4 to the transfer position follow with their butts 6a a track defined by the cams of lower cam ring 9.

The sliders 2 and 4 are each provided, in a known manner, with butts 2a, 2b, 2c and 4a, 4b, 4c, respectively. Furthermore, the sliders are allowed to perform an oscillatory move- ment with fulcra at 2d, 4d respectively, under the action of special cams 10a and lOb, as described hereinafter, which through the butts 2c, 4c respectively, push the slider end portion toward the bottom of their respective grooves in the needle cylinder, thus causing tip portions 2e, 4e respectively to project outwards, in the proximity whereof hooks 2f, 4f respectively, are located for hooking up needles 5.

The tracks followed by the vertically aligned sliders 2 and 4, specifically by the butts 2b and 4a thereof; prior to the transfer of a corresponding needle and during such a transfer, are denoted respectively with the numerals 11 and 12. Track 13 of Figure 1 represents instead the "floating" track, also termed above as the second track. The arrow-heads F indicate the movement of the sliders and needles with respect to the cam rings. The full line A depicts the path followed by the ends 2e of the sliders 2, the dashed line B shows the path of the upper hooks Sa of the needles to be transferred, and the dotted line C indicates the level of the upper hooks 5a of the needles in the "floating" position.

The instance is now considered of a slider 4 correctly driven to effect the transfer, in a known manner, of a needle 5 from the lower needle cylinder to the upper needle cylinder.

The slider 4 is first driven, by means of a special selecting jack (not shown), which acts on a cam 14, to engage the track 12 with its butt 4a. The control of the selecting jack is effected by a special selecting lever, not shown, actuated by a pattern drum provided with so-called safety teeth or pins. The needle 5 has its upper hook 5a at level B, slightly lower than level A of the overlying tip of the slider 2, which follows the track 11 with its butt 2b (see the rightmost slider and needle in Figure 1). As the slider 4 reaches with its butt 4a a raising portion 15a of a cam 15, the slider 2 reaches with its butt 2a a descending portion 1 6a of a cam 16 and the mutual approach of the slider 2 and needle 5 begins, which inserts the tip 2e of the slider 2 between the latch Sb and hook Sa of the needle 5.The progressive descent of the slider 2, controlled by the portion 16a, and the progressive raising of the slider 4, controlled through the butt 4a engaging with a raising cam 17, causes a gradual opening of the latch 5b under the action of the tip 2e.

Thus, the needle is fully opened and allowed to go over to the transfer.

Subsequently, the slider 2 comes down with its butt 2b along a cam 22, and on meeting with its hook 2f the needle hook 5a, tilts automatically into a recess 18a, thereafter it hooks up the needle due to the tilting movement into the recess 18a, but immediately afterwards meets with its butt 2c the cam 10a which urges it to tilt into a recess 18b, thus releasing the needle which in the meantime begins to come down dragged by the slider 4, which descends along a cam 24 with its butt 4b.

Thereafter, the slider 4 which carries the needle involved in the transfer for rib knitting, meets its respective selecting jack 6, which, in its raising movement, urges it to push the needle 5 toward the slider 2 and to automatically tilt into a recess 18c.

At the end of said recess 18c, the slider 2 swings back, hooks up the needle and drags it along following a raising portion of the track 11, while the slider 4 concurrently releases the needle 5 and tilts into a recess 19b, urged to do so by the cam lOb engaging its butt 4c.

Since the latch 5b of the upper hook 5a of the needle 5 has been previously opened, as described above, no breakage failure occurs either in the needle 5 or slider 2 at the instant of the swinging back thereof into the respective cylinder groove.

By contrast, in the prior art machine, when a slider 4, owing to a wrong arrangement of the pins on the specially provided pattern drum, fails to be lifted to the track 12, it stays with its butt 4a in the "floating" track 13.

Such is the case with the hatched slider 4 on the right of Figure 1. This will stay with its butt 4a in the track 13 until it is lifted by its respective selecting jack 6 (hatched slider 4, on the left), which selecting jack is not affected by the setting error on the preceding pattern drum. The raised slider 4 lifts its respective needle 5 to a position whereat the facing slider 2 in the upper needle cylinder is tilted outwardly by the cam 10a. If the latch 5b, as is often the case, is not in the opened state, the needle 5 and slider 2 break when the latter swings back and is pressed to the bottom of its groove by a cam 20.

To overcome this drawback, the invention provides an auxiliary cam 21 slightly upstream of the transfer area (Fig. 2), the cam being shaped to bring the needles associated with the sliders 4, which are guided with their butts 4a in the "floating" track 13, to a level of contact with the tips 2e of the respective sliders 2 in the other needle cylinder, such as to effect the opening of the closed latches 5b.

More specifically, the position of the auxiliary cam 21 and the height thereof are such as to bring the needles S to a level higher than the height reached by the tip 2e of the corresponding sliders 2 after the latter have been lowered by engagement of the cam 22 with the butts 2b, thereby a relative movement is implemented between the tips 2e and underlying needles effective to produce a progressive opening of the corresponding latches.

This is best shown in Figure 3. It should be noted here that during the first two phases shown, a relative linear motion occurs for a certain length of the needle and slider, which causes the tip 2e to progressively open the latch 5b, while later on, as the outward tilt of the slider begins, the latch is further opened to approximately a horizontal position of the same, owing to the tip 2e engaging with the end portion of the latch.

At this stage, even if the latch fails to open fully, e.g. does not drop under its own weight, but stays in the position reached, no failure can occur, since as the slider swings back the tip 2e follows again the same path which it followed when swinging out, thereby it cannot hit the latch. Consequently, it is no longer necessary to calculate the height of the cam 21 such as to open the latch to a nearly horizontal position, a narrower opening being quite adequate. At the end of the swinging out and back steps, the slider and needle start again to move linearly toward each other, so that the latch is fully opened and the hooking up is performed as usual, as shown for the sliders 2 and 4 on the extreme left of Figure 2.

By providing the auxiliary cam 21, not only are the needles and sliders effectively protected against breakage but it also becomes possible to transfer those needles the sliders whereof have erroneously been started along the "floating" track 13.

The sliders 4 which, on the contrary, have been correctly directed to this track 13, since uninvolved in knitting at the feed immediately following the transfer area, are also subjected to the action of the cam 21, wherefor they advantageously bring their respective needles to the latch opening position, to be then lowered once again by a successive cam 23 to the level of the "floating" track 13, without ever going to a transfer proper since no selecting jack 6 is provided for them in the raise phase along the cam ring 9.

The auxiliary cam 21 may be either movable or stationary, and may be arranged at the level of the track 13, as shown in full lines in Figure 2, or alternatively at a different height, as shown in dotted lines, whereat it acts on the butts 4b of the sliders 4 to cause the latter to carry out the same movement as described above.

The invention, as described hereinabove, also reduces the pattern drum preparation time, as it is no longer required that the safety pins be set on these drums. The resulting advantage, in relation to the elimination of possible errors, is evident.

Obviously, the invention may find appli cation also on different machines from the one considered, for example on machines set to execute the knitting known as "linksfloating", by floating the needles in the lower needle cylinder on the first feed when the pattern drum is on the lower needle cylinder.

The invention may also be applied for transferring needles from the upper needle cylinder to the lower one, that is for passing from rib knitting to plain knitting. Furthermore, the invention is suitable for large diameter double-cylinder circular knitting machines provided with double-hook needles.

WHAT WE CLAIM IS: 1. A double-cylinder circular knitting machine having cams for opening the needle latches, sliders facing each other within the two needle cylinders and needles each engaging a respective one of said sliders, control cams for engaging butts of said sliders defining at least a first track for butts of the sliders associated with the needles to be transferred and at least a second track for butts of the sliders associated with the needles not to be transferred, wherein the cams further comprise an auxiliary cam located upstream of the transfer area and shaped to bring the needles associated with all the sliders which have butts guides'in said second track to a level of contact with the respective facing sliders of the other needle cylinder, thereby providing a gradual opening of the needle latches by said facing sliders, and a subsequent cam shaped to bring the sliders associated with the needles not selected for the transfer back to the level of said second track.

2. A machine according to claim 1, wherein said auxiliary cam is arranged to be radially movable with respect to the needle cylinders.

3. A machine according to claim 1, wherein said auxiliary cam is located at the level of said second track to interact with the butts of the sliders movable along said second track.

4. A double-cylinder circular knitting machine substantially as herein described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. which it followed when swinging out, thereby it cannot hit the latch. Consequently, it is no longer necessary to calculate the height of the cam 21 such as to open the latch to a nearly horizontal position, a narrower opening being quite adequate. At the end of the swinging out and back steps, the slider and needle start again to move linearly toward each other, so that the latch is fully opened and the hooking up is performed as usual, as shown for the sliders 2 and 4 on the extreme left of Figure 2. By providing the auxiliary cam 21, not only are the needles and sliders effectively protected against breakage but it also becomes possible to transfer those needles the sliders whereof have erroneously been started along the "floating" track 13. The sliders 4 which, on the contrary, have been correctly directed to this track 13, since uninvolved in knitting at the feed immediately following the transfer area, are also subjected to the action of the cam 21, wherefor they advantageously bring their respective needles to the latch opening position, to be then lowered once again by a successive cam 23 to the level of the "floating" track 13, without ever going to a transfer proper since no selecting jack 6 is provided for them in the raise phase along the cam ring 9. The auxiliary cam 21 may be either movable or stationary, and may be arranged at the level of the track 13, as shown in full lines in Figure 2, or alternatively at a different height, as shown in dotted lines, whereat it acts on the butts 4b of the sliders 4 to cause the latter to carry out the same movement as described above. The invention, as described hereinabove, also reduces the pattern drum preparation time, as it is no longer required that the safety pins be set on these drums. The resulting advantage, in relation to the elimination of possible errors, is evident. Obviously, the invention may find appli cation also on different machines from the one considered, for example on machines set to execute the knitting known as "linksfloating", by floating the needles in the lower needle cylinder on the first feed when the pattern drum is on the lower needle cylinder. The invention may also be applied for transferring needles from the upper needle cylinder to the lower one, that is for passing from rib knitting to plain knitting. Furthermore, the invention is suitable for large diameter double-cylinder circular knitting machines provided with double-hook needles. WHAT WE CLAIM IS:

1. A double-cylinder circular knitting machine having cams for opening the needle latches, sliders facing each other within the two needle cylinders and needles each engaging a respective one of said sliders, control cams for engaging butts of said sliders defining at least a first track for butts of the sliders associated with the needles to be transferred and at least a second track for butts of the sliders associated with the needles not to be transferred, wherein the cams further comprise an auxiliary cam located upstream of the transfer area and shaped to bring the needles associated with all the sliders which have butts guides'in said second track to a level of contact with the respective facing sliders of the other needle cylinder, thereby providing a gradual opening of the needle latches by said facing sliders, and a subsequent cam shaped to bring the sliders associated with the needles not selected for the transfer back to the level of said second track.

2. A machine according to claim 1, wherein said auxiliary cam is arranged to be radially movable with respect to the needle cylinders.

3. A machine according to claim 1, wherein said auxiliary cam is located at the level of said second track to interact with the butts of the sliders movable along said second track.

4. A double-cylinder circular knitting machine substantially as herein described with reference to the accompanying drawings.