US2229928A

US2229928A - Warp knitting machine

Info

Publication number: US2229928A
Application number: US310078A
Authority: US
Inventors: Morrison John Lamb Murray
Original assignee: FNF Ltd
Current assignee: F N F Ltd; FNF Ltd
Priority date: 1939-05-16
Filing date: 1939-12-19
Publication date: 1941-01-28
Anticipated expiration: 1958-01-28
Also published as: GB528886A

Description

Jan 28, 1941- J. L. M. MoRRlsoN 2,229,928

, WARP KNITTING MACHINE Filed Deo. 19, 1939 :5 sheets-sheet 1 Fig. I.

M-II

A ltrney Jan. 28, 1941.

.1. L. M. MORRISON V WARP `KNTTING: MACHINE 3 Sheets-Shet 2 Filed Dec. 19, 1939 Fig. 2.`

Inventor Jan. 28, 1941. J. L.. M. MORRISON WARP KNITTING MACHINE Filed' Dec. 19', 1939 5 sheets-sheet s A Homey Patented Jan. 28, 1'941 waar KNITTING MACHINE -John Lamb Murray Morrison, Bristol, England,

assignor to F, N. RLimited, Gloucester, England, a British company Application December 19, 1939, Serial No. 310,078 In Great Britain May 16, 1939 11 Claims.

. This invention relates to warp knitting machines. In such machines there are warp guide bars which are moved to and fro longitudinally.

and also'rocked 'about a parallel axis to enable the warp guides, carried by the bars,.to position threads on the knitting needles. The longitudinal or lapping movements of al guide bar are caused in one direction by a pattern cam and in the other direction [by a spring to the extent perlill mitted by the cam. The inventlonis concerned -with the 'spring and associated mechanism for nitude, the cumulative distance moved ina num' du ber of cycles may be much greater. Howeventhe local action is 'substantially the same in each knitting cycle, Whatever the distanceof the guide bar from a mean position. Therefore, the force exerted Iby the spring should, to a ilrst approxi- 26 mation, remain constant in al1 positions, because the minimum value of the force isdetermined principally by the acceleration it must give to the bar and alsoto a small extent by'the force necessary to overcome frictional resistance to motion 80' and the longitudinal component of the force -due to the Warp tension, and the maximum value should be as near the minimum value as possible to avoid excessive stresses and wearie l Further, it is desirable, to a closer approximami4 tion, `for the spring force to have its greatest ,value when the guide bar is at or near its mean j position, because it is in the vicinity of' this position that relatively simple fabrics are usually knitted.l For reasons -asscciatedwith the design 40' of the other parts of the machine, it is possible to knit such simple fabrics at speeds which entail greater accelerations of the guide bar than in the case of fabrics of morecomplicated pattern which necessitate a greater/total displacement 45 of the guide bar. u

It will, therefore, be seen that the ideal spring mechanism should provide a force which is. to a first approximatiomconstant over the whole range of vtravel of the guide bar but which to a W closer approximation attains a greater value at or near the mean position of the guide Ibar than when displaced 4towards the extreme limits yof travel.` Hitherto the spring mechanism has been designed with a view to attaining as nearly as ,havingl a low rate in order to keep the force as nearly constant as possible. However, the force has a minimum value at one end of the longitudinal line of travel of the guide bar, and a maximum value, which differs appreciably from its -5 minimum value, at the other end. Such a spring has low natural frequencies of surging, and if the machine runs at such a speed that a vibration in resonance with any one of the natural frequencies of surgingoccurs in the supports, thev l0 spring surges to an extent which is not readily calculable and the force actually applied to the guide bar may differ greatly from that which would be applied when the spring was'not surging. y Then the guide bar may `no longer be posi- A15 tioned by the cam and serious damage to the knitting machine may result. y

From the foregoing it Will lbe appreciated that the spring mechanism for loadingv the guide bar should have a spring with no natural frequency of surging as small as any appreciable' vibration which may be imparted to it, and the mechanism shouid'apply to the guide bar aforce which does not vary greatly with'the position of the guide bar, and which reaches a maximum value when the gu'idmbar is at or near its mean position anda minimum value when the guidebar is near its limits of travel. The aim ofv the present in-v vention is to provide spring mechanism which approaches these conditions as nearly as possible,

According to the present invention, a guide bar is arranged to be moved longitudinally in one direction bya cam and in the other direction by a short stiff spring, acting -on the guide bar through a lever arranged so that the force appliedlby the spring to the' guide bar undergoes small changes irf magnitude in relation to they corresponding movements of the guide bar. Conveniently. the lever may have one arm at right angles to the guide bar when theA latter is at its 40 mean position, anda shorter arm, constituting a continuation of the irstfx-mentioned arm beyond its pivotal axis, acted upon by a helical compression spring, the second arm subtending an obtuse angle with the rst mentioned arm and an obtuse angle with the spring axis. In this arrangement the rst arm is pivotally connected through flexible links to the guide bar.

In order that the invention may be clearly- .4550 understood and readily carried into effect, one construction in accordance therewithwill now be described by way of example with reference to the accompanying drawings, in which:

58 possible the first of these conditions, the spring Figure 1 a plan' of part of theguide bar v55 actuating mechanism in a warp knitting machine;

Figure 2 is a section on the line lI-II in Figure 1, the relative position of certain further parts being shown by chain lines;

Figure 3 is a section on the line III- III in Figure 2 showing some of the parts appearing in Figures 1 and 2;A and Figure 4 is an elevation of certain parts appearing in Figures l and 2, as viewed when looking in the direction of the arrow IV in Figure 2.

The drawings showthe ends of two guide bars I and I' mounted in a warp knitting machine. As is usual in such machines, each guide vbar carries a number of blocks 2 and 2' from which project the warp guides 3 and 3'. 'I'he guide bars are carried by a rock shaft 4,A thePOSition of which, relatively to the guidbars is indicated by chain lines in Figures 2 and 4, through the medium of supporting assemfblies '5,shown by chain lines in Figure 2, distributed along the length of the rock shaft and secured thereto. The guide bars are arranged to reciprocate to and fro along their lengths relatively to the supporting assemblies. Thus, the necessary movements are imparted to the warp guides by rocking .the rock shaft 4 about its axis and by moving the guide bars to and fro longitudinallyf In the rocking movements, the

warp guidesl

8 and 3 pass between the knitting needles (not shown) and, in the longitudinal movements, the warp guides lap the needles. It is the mechanism for imparting these to and fro longitudinal movements to the guide bars thatillustrates the present invention, and lthe mechanism for moving the guide .bar I' to and fro will be particularly described, the equivalent mechanism for the guide bar I" being precisely the same as that for the guide Ibar I.` Parts associated with the guide bar I' that are the same as parts for the guide bar I bear the same reference numerals rbut with the suix The movement to the right in each reciprocation of the guide bar I isl imparted by a rotary cam 50 (part of which appears in plan view'in Fig. 1) acting on a roller 5I on a tappet 6 between which and the guide bar I, a push rod 'I is interposed, the tappet being guidedin a casing 52. A pair of

lever parts

8 and 9 extends to points on each side of the push rod 1 from a common journal I0 (Figure 2) and these are connected at their outer ends to the adjacent endof the guide bar I by flexible metal strips II and I2, which are pivoted to the lever parts 8 and V9 -and to the guide bar I.

.vides the second arm of the lever, is formed atone side near its lower end with a V-shaped recess I5, in which a V-shaped projection I6y lies to provide a knife edge pivot at A. The projection is formed on a member/,I1 against which one end of a helical compression spring J8 bears. This spring extends through a casing I9, closed steel ball 28 rests. This ball bears, in turn, on a member 24 which is formed with a concave spherical surface 25 of larger lradius of curvature, so providing a universal-joint which imposes no appreciable directional restraint on the axis of the spring I8. 'I'he member 24 is screwed into a cap 26 which serves to close the end of the casing I9, and it is through this cap that the spring force is transferred to the machine frame 20. The spring force can be adjusted at 10 will by screwing the cap 26 further into or out of the casing I9.

Now the length of the arm I4 of the two-armed lever, that is the distance A-B (Figure 3) is, in the example being described, 11/4 inches. The 15 length of the other arm, that is the distance f- B-C, is approximately 4 inches. The angle subtended-between these two distances, that is the angle a in Figure 3, is approximately and the angle between the arm A-B and the spring 20 axis, i. e. the angle b (Figure 3), is also approximately 135 when the guide bar is in its mean position.

It will be appreciated that, owing to the difference in length of the two arms of the lever 25 extending respectively on each side 'of the axis of the journal II), the spring I8, which has a high enough rate to avoid surging, undergoes changes in length which are less than the longitudinal movements of the guide bar. Further, owing toy 30 the angle between the two arms, i. e. the angle a (Figure 3), the changes which occur in the spring force are'not applied to the guide bar without modication. The long arm, consisting -of the

parts

8 and 9, extending to one side of the axis 35 of the journal I8, is at iight angles to the guide barQ when the latter is in its mean position, and the force applied to the guide bar decreases slightly as it travels from that position to either of the extremities of Iits stroke. Thereason for 40 this will be realized from the fact that the applied turning moment in any position within the range of movement of the guide bar is equal to the product of theforce due to the spring I9 at that position and the perpendicular distance be- '45 tween the line of action of this force and the axis B of the two-armed lever. Further, owing to the angle between the two arms AB and BC, the said perpendicular distance increases when the spring expands and decreases when the 50 spring is compressed. Therefore, although the stress in the spring I8 changes appreciably as the lever moves from one extreme position to the other, the turning moment; and therefore the force on the guide bar remains more nearly-55 uniform. With a proper choice of the variables, the ideal relationship between the guide bar movement and the force exerted thereon may be very closely approached. In the construction being particularly described, the rate of the '60 spring I8 is 714 lbs. per inch, and the maximum at oneen`d, xed to` the machine frame 20. The" other end of the spring I8 bears against a member -2I formed on its side remote from the spring I 8 with a spherical depression 22 in which a hard guide bar movement which can be accommodated is 1 inch on either side of the mean position in which it is sho'wn in Figure 1. When the closure member 26 for the casing I9 is screwed '65 to a position such that the spring-force is 568 lbs. in the mean position of the two-armed lever, the force on the guide bar is 149 lbs.- Then, respectively at the ends'lof the guide bar stroke, the spring forces are 354 lbs. and 729 lbs., and 70 the forces on the guide bar are 119 lbs. and 130 lbs. When the spring force is increased to 605 lbs. in the mean position, the force on the guide bar is 159 lbs. The latter changes to 131 lbs. and 137 lbs. respectively at the extreme positions, 75

` andthe spring `forces are 565 lbs. and 940 lbs'.

parts

8, 9 and l2, is formed with three barrelr In order to-equalise the loads on the flexible strips il and I2 while providing safety should one of the strips or one of its end connections break, the pin I3, which'couples the three lever shaped surfaces, as shown Ain Figure 2, which bear respectively on cylindrical bores in the lever part-

s

5, 8 and 9. A second pin 30 rests in clearance holes in the

levers

8 and 9 and is normally inoperative. In the event of breakage, however,

this pin 30 acts as a coupling device between the centre member 5 and the guide bar.

To enable the guide bar to be relieved of the spring I8, a bolt 3l, carried by the machine frame 20, is screwed up to bear against an abutment 32 on the two-armed lever, this abutment being formed on the centre lever member 5.

In the rocking movements of the guide bar about the axis of the rock shaft l, the push rods I and 1' undergo slight angular displacements "and to accommodate these, ball and socket joints are provided at the ends of the rods. In Figure 4 the joints for the rod l' appear and bear the reference characters 33 and 34.

I claim:

l. In a warp knitting machine, in combina'-` ticn, a Warp guide bar mounted for longitudinal to and fro movement, a cam operative to move said guide bar longitudinally inone direction, a

sti resilient device, and a lever interposed between said bar and said device and operative to apply to said bar a force, derived from said device, to move said bar longitudinally in the other direction While said resilient 'device undergoes small changes in strain in relation to the extent ci the longitudinal movements of said guide bar.

2. In a warp knitting machine, in combination, a warp guide bar mounted for longitudinal to and iro movement, a cam operative to move said guide bar longitudinally in one direction, a lever mounted to swing to and fro about an axis and operatively connected to said guide bar, and a stiff resilient device operative to act on said lever to move said guide bar longitudinally in the other direction, said lever and said resilient device beiner arranged so that the perpendicular distance between the line of action of said resilient device and said axis increases as said device relaxes when said guide bar moves from a position substantially at the centre of its stroke to a position at one end of its stroke, and decreases as said device is stressed while said cam is moving said guide bar from said position to the other end oi its said guide bar longitudinally in one direction, a

cranked two-armed lever having a shorter arm' and a longer arm operatively connected to said guide bar, and a com-pression spring mounted to act on said shorter arm, at a point Within the smaller angle subtendedby said two arms, to move 'said guide bar longitudinally in the other direction.

5. In a warp knitting machine, in combination, a warp guide bar mounted for to and fro movement, a cam operative to move said guide bar longitudinally in one direction, a cranked twoarmed lever having a shorter arm and a longer arm operatively connected to said guide bar, and a helical spring mounted to act on said shorter arm, with its line of action substantially parallel to said guide bar, to move said guide bar longitudinally in the other direction. v

6. In a warp knitting machine, in combination, a warp guide bar mounted for to and fro longitudinal movement, a cam operative to move said 'guide bar longitudinally in one direction, a cranked two-armed lever having a shorter arm and a longer arm operatively connected to said guide bar, an abutment, and a stiff helical compression spring pivotally applied at on end to said abutment and pivotally applied at the other end to said shorter arm to move said guide bar longitudinally in the other direction.

7. In a warp knitting machine, in combination, a warp guide bar mounted for to and fro longitudinal movement, a cam, a push rod substantially in alignment with said guide'bar and inter.. posed between-same and said cam, enabling said cam to move said guide bar longitudinally in one direction, a pivoted lever having parallel parts lying respectively on opposite sides of said push rod, two tension members respectively connecting said parts to said guide bar, and spring means arranged to act on said lever to move said guide bar in the other direction.

` 8.111 a warp knitting machine, in combination, a warp guide bar mounted for to and fro longitudinal'movement, acam, a pushrod substantially in alignment with said guide bar and interposed'between same and said cam enabling said cam to move said guide 'nar longitudinally in one direction, a pivoted lever including two parts lying respectively on opposite sides of said push rod and mounted to swing about the lever axis and means interconnecting said parts while permitting same to undergo limited movement relatively to each other about saidlever axis, two tension members respectively connecting said parts to 1 said guide bar, and a resilient device arranged to act on said lever to move said guide bar in the other direction.

9. In a warp knitting machine, in combination,

'ya warp guide bar mounted for to and fro longitudinal movement, a cam, a push rod substantially in alignment with said guide bar and interposed between same and said cam to move said -guide bar longitudinally in one direction, a two-` armed lever including two parts providing a longerarm of said lever and formed respectively with cylindrical bores, and a third part located .members respectively connecting said first-men- "move said guide bar in the other direction.

10. In a lwarp knitting machine, in combina` tion, a warp guide bar mounted for to and fro longitudinal movement and for to and fro` movement about an axis parallel thereto, a cam oper-r ative to lmove said guide bar longitudinally in one direction, a cranked two-armed lever having a shorter arm and allonger arm disposed to lie substantially perpendicular to said guide bar when the latter is substantially at the centre of its stroke, a flexibletension -member connecting said longer armvand said guide bar, and a helical spring mounted to Aact, with its line of action substantially parallelrtosaid guide bar, on said shorter arm to move said guide bar longitudinally yin the other direction.

and a. longer arm disposed to lie substantiallyl perpendicular to said guide bar when the latter is substantially at the centre of its stroke, a flexible tension member lying substantially parallel to Qsaid guide bar and. connecting the latter to said longer arm, and a resilient device arranged to act on said shorter arm to move said guide bar longitudinally in the other directio JOHN LAMB MURRAY MORRISON.