US2731818A - Cam mechanism of knitting machines - Google Patents

Description

J 4, 1956 .1. E. LYNAM ET AL CAM MECHANISM OF KNITTING MACHINES 5 SheetsSheet 1 Filed March 4, 1952 Inventors: Term Eoumzo LYNRM8 BASIL PoMERoV CAMPER Jan. 24, 1956 J. E. LYNAM ET AL CAM MECHANISM OF KNITTING MACHINES 5 Sheets-Sheet 2 Filed March 4, 1952 Inventors; Tomy EDWARD LYNA Q, BAsIL PoMERoy COOPER Jan. 24, 1956 J, E. LYNAM ET AL 2,731,818

CAM MECHANISM OF KNITTING MACHINES Filed March 4, 1952 3 Sheets-Sheet 5 Inventors: Tor-m EDWARD Lwvmq PoMERoy CooPER CAM MECHANISM or KNITTING MACHINES John Edward Lynam, Nottingham, and Basil Pomeroy Cooper, Loughborough, England, assignors to William Cotton Limited, Loughborough, England Application March 4, 1952, Serial No. 274,758

Claims priority, application Great Britain March 5, 1951 9 Claims. (Cl. 66-82) This invention concerns knitting machines and cam operated mechanism therein. In knitting machines, particularly Cottons patent and other straight bar knitting machines, it is customary to operate certain devices each by mechanism comprising a rotary cam and a truck lever carrying a truck or cam follower engaging said cam, and to cause the truck to press against the cam and to follow its contours by means of a return spring extending between the lever and a fixed anchorage. Particularly, in straight bar knitting machines the devices (e. g. the needle bar or catch bar) to be moved have considerable inertia and since a spring has to move its device while the follower is descending the flank of the cam the spring needs to be very strong. It therefore follows that the strong spring throws a considerable load on the machine while the follower is ascending a flank of the cam, and since at one period the spring pressure assists rotation of the cam and at another resists it the torque required to drive the cam fluctuates heavily with a consequent detriment to smooth running of the machine. Further, it is difiicult to turn the machine by hand and to stop at a given stage, for the spring pressure will often cause the machine to run backward or forward from said stage.

,An object of this invention is a construction which eliminates or mitigates these disadvantages. While the invention is chiefly applicable to straight bar knitting machines it is to be understood that it is applicable to other knitting machines also, such for example as warp knitting machines.

The invention provides a knitting machine having cam mechanism for actuating parts of the machine comprising at least one pair of complementary cams coupled together to rotate in unison about the substantially parallel axes, and cam follower means comprising truck means rotatable about a single axis between and parallel to the cam axes and closely constrained by the peripheries of the cams so as to be positively displaced thereby in opposite directions transversely between the cam axes. By complementary cams-there is meant cams the contours of which are so formed (having regard to the relative speeds of rotation of the two cams) that one cam produces movement of the follower means in one direction .and the other cam produces movement in the reverse direction. It will, therefore, be appreciated that a cam mechanism according to this invention may dispense with a return spring such as has hitherto been used, although if desired a light spring may be employed to bias the cam follower means against one of the cams.

The contours of the cams are desirably so designed that at each region where inertia force tends to cause the follower means to deviate from its designed movements as predetermined by the contour of one cam, this tendency is corrected by the contour of the other cam. (Such inertia 2,73 1,818 Patented Jan. 24,. 19 56 force may be due to the mass of the moving parts, or to the mass thereof together with acceleration or deceleration called for by the contour of one cam.) To achieve this result the cams may be so formed that the follower means is at all times closely constrained between the peripheries of the cams. That is to say each crest on either cam is matched by a hollow on the other cam, and each rise or fall on either cam is matched on the other cam by a fall or rise as the case may be.

The two cams preferably, but not necessarily, rotate in the same direction.

The cam follower means may be constituted by a single follower such for example as a truck or roller, opposite portions of which are engaged by the two cams. Alternatively, if the cams are staggered there may be one follower engaged by one cam and another follower engaged by the other. The follower means is preferably mounted on a single lever, e. g. one the general length of which is substantially normal to a plane containing the axes of the two cams. Alternatively, there may be two levers which are coupled together, particularly if the cams are staggered.

In the application of this invention to a Cottons patent or other straight bar knitting machine, two substantially horizontal cam shafts are employed, these cam shafts being coupled together to rotate in the same direction. Certain of the heavy duty cams (and notably that which produces the movements of the needle bar, both up and down and towards and away from the pressers, and that which moves the catch bar to and fro to advance the dividing sinkers, and to retract all sinkers) are mounted at suitably spaced locations on what is, for convenience, called the main cam shaft. Each of these cams has its counterpart or complementary cam on the other cam shaft which for convenience will be regarded as the counter cam shaft. For each pair of cams, there is a lever which extends in a direction which is substantially normal to'the plane containing the axes of the two shafts and carries a truck which is disposed between the two cams, so that the latter act on two diametrically opposed parts of the truck periphery. Each counter part cam is so formed that the associating truck is at all times closely confined between the peripheries of the two cams. Therefore, each pair of cams imparts positive movements in both directions to the associated truck and truck lever, although if desired a light spring may be provided for biasing the truck against the main cam.

Both cam shafts are arranged to be shogged when it is desired to modify movement of the parts which they operate, as for example when the machine goes into a fashioning motion. For this purpose, alongside each cam there is either a plain cam or a further cam designed to produce the modified movements.

Certain of the light duty cams, such for example as also within the scope of the invention to provide some of the main cams on one shaft and others of the main' cams on the other shaft, so that each shaft carries some of the main cams and some of the counter cams.

Best results are obtained if the driving connections between the two cam shafts are so arranged that there is little or no back lash, so that the two cams of a pair cannot get out of phase with one another. It is also preferred that the axes of the two cams and truck shall lie in substantially the same plane.

In addition to the positive movement in both directions which is provided by mechanism according to this invention, a further advantage is that if the cams of a pair rotate in the same direction the truck will roll on the periphery of each of them with a minimum of slipping.

"Ihe above and other features of the invention are set forth in the appended claims and are disclosed in the detailed description given by way of example of the particular embodiments illustrated in the accompanying drawings in which Figure I is a general sectional view of a Cottons patent knitting machine according to the invention.

Figure 2 is a detail view of cams for needle bar raising and lowering movement.

'Figure 3 is a detail view of cams for catch bar movements.

Figure 4 is a detail view of cams for needle bar forward and rearward movement.

Figure 5 is a detail of drive and shogging means for cam shafts.

Figure 6 is a plan view of a modification.

Referring now to Figure 1 the Cottons patent straight bar knitting machine shown employs conventional needles 1, sinkers 2, knocking-over bits 3, and jack springs 6 which are operated from cams on cam shafts 4, 5. The jack springs 6 are conveniently operated by conventional cam 7 on cam shaft 5 through the medium of truck arm 8, the knocking-over bits 3 are conveniently operated from conventional cams 9 and 9a on shaft 5 through the medium of truck levers 10 and 10a and the catch bar raising and lowering is conveniently effected by conventional cam 11 on cam 5 through the medium of truck lever 12.

However, the needle bar raising and lowering movements, needle bar forward and rearward movements, and the catch bar forward and rearward movements are each effected by a pair of cams coupled together about the substantially parallel axes of the cam shafts 4 and 5 by one of each pair being on the shaft 4 and the other of each pair being on shaft 5 at an opposite location and complementary to the first of the pair, and cam follower means comprising a truck lever for each pair of cams is disposed with its truck between the appropriate cams so as to be rotatable about a single axis between and parallel to the cam axes and closely constrained by the periphcries of the cams so as to be positively displaced thereby in opposite directions transversely between the cam axes. Preferably as shown the trucks are disposed on an axis substantially in the same plane as that containing the cam axes. More specifically, cam 13 (Figure 2) on shaft 5 is of conventional type for needle bar raising and lowering movements, and cam 14 on shaft 4 is: complementary (and of dissimilar shape) to cam 13 i. e. rises and falls on cam 14 are opposite to those on cam 13 so that like movements are given to the truck 15 of truck lever 16 by both cams. Similarly as shown in Figure 3, cam 17 on shaft 5 is of conventional form for the catch bar forward and rearward movement and cam 18 on shaft 4 is complementary (and of dissimilar shape) to cam 17 for operating on truck 19 of truck arm 20; Figure 4 shows that cam 21 on shaft 4 is of conventional type for needle bar forward and reverse movement and cam 22 on shaft 5 is complementary (and of dissimilar shape) to cam 21 for operating on truck 23 of truck arm 24.

Lever mechanism connecting truck arm 20 to the catch mechanism 25 for sinkers 2 may be conventional as shown, but truck arm 16 has a variable connection with needle bar 26 to allow for maintaining the needles down at desired times such for example as when passing a thread carrier across the needles without knitting say for a yarn change, or during welt forming or at other desired times.

For this purpose the arm 16 is free on shaft 27 and fixed on said shaft there is the conventional arm 28 attached to the needle bar 26 and a coupling arm 29. This coupling arm 29 is connected to the truck arm 16 by toggle links 30 and the centre pin 31 thereof is adapted to ride in a slot 32 in'a truck lever 33. This lever 33 has a truck 34 which normally rides on a circular cam disc 35 on shaft 4 such as to maintain the toggle rigid thereby transmitting movements of truck lever 16 to the needle bar to effect normal movements of the needle bar. When however it is desired to maintain the needles down as aforesaid, truck 34 is shogged by shogging means 36 onto a second cam 37 and this cam 37 is so shaped that it moves the truck lever 33 and varies the height position of slot 32, this in turn raises and lowers pin 31 so as to vary the setting of the toggle links, and this variation constitutes variation of leverage between the truck lever 16 and the needle bar 26 such that movements of the truck lever 16 by cams 13 and 14 are canceled out i. e. not transmitted to the needle bar which is consequently held in a lowered position as desired.

Conventional means for varying the quality or stitch size of the fabric loops consists of arm 38 which is adjustable from pattern mechanism (not shown) to adjust the extent of forwards and rearwards motion of the needle bar by limiting the distance of movement of peg 39. To permit the adjustment, cams 21 and 22 may be relieved say as indicated at 40 and in Figure 4. There may be a light spring 41 for biasing the truck of lever 24 towards cam 21.

Figure 5 illustrates that the cam shafts 4 and 5 may be driven in the same direction from a motor 42, through chain drive 43, and gears 44, 45, 46. Means are preferably provided for preventing back lash such for example as plate gears 47, 48 fixed on gears 45, 46 respectively and which are circumferentially adjustable to ensure close connection of the gear teeth.

Said Figure 5 also illustrates a form of shogging means comprising a fork lever 49 engaging shaft 4 pivotally coupled to a fork 50 engaging shaft 5 so that the two shafts may be shogged by common shogging mechanism operating on shaft 5 (not shown). Alternatively the shafts may be shogged by separate mechanism one for each shaft.

As illustrated, each of the trucks 15, 19 and 23 is preferably mounted on a single lever the general length of which is substantially normal to the plane containing the axes of the two cams operating it. Figure 6 indicates that any pair of complementary cams may have its cams staggered along the parallel axes of the shafts 4 and 5, there being a separate truck for each cam of a pair, and the two tmcks being spaced along the aforesaid single axis between and parallel to the cam axes and coupled together for operation in unison.

We claim:

1'. A knitting machine having cam mechanism for actuating parts of the machine comprising at least one pair of complementary cams coupled together to rotate in unison about substantially parallel axes, and cam follower means comprising truck means rotatable about a single axis between and parallel to the cam axes and closely constrained by the peripheries of the cams so as to be positively displaced thereby in opposite directions transversely between the cam axes.

, 2. A knitting machine according to claim 1 having the cam follower means disposed on an axis substantially in the same plane as that joining the cam axes.

3. A knitting machine according to claim 1 having the cams of dissimilar shape.

4. A. knitting machine according to claim 3 being a Cottons patent or other straight bar knitting machine.

5. A knitting machine according to claim 1 having means for rotating the cams in the same direction.

6. A knitting machine according to claim 1 having the cam follower means constituted by a single truck and the cams opposed.

2,781,818 5 a 6 I 7. A knitting machine according to claim 1 having the biasing the cam follower means onto at least one of the cams staggered along the parallel axes and a separate cams. truck for each cam, the two trucks being spaced along the single axis and coupled together for operation in References Cited in the file of this Patent kntf h. t 1 1 h 5 UNITED STATES PATENTS 1 ing mac me accor mg 0 c alm avmg a single lever the general length of which is substantially 1165478 wmkler 1915 normal to a plane containing the axes of the two cams, FOREIGN PATENTS and the cam follower means is mounted on the said lever. 11982 Great Britain f 1847 9. A machine according to claim 1 having spring means 10

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