EP0974692A2

EP0974692A2 - Needle selecting apparatus for circular knitting machines

Info

Publication number: EP0974692A2
Application number: EP99305838A
Authority: EP
Inventors: Takao Shibata; Yasuo Nakamura
Original assignee: Precision Fukuhara Works Ltd
Current assignee: Precision Fukuhara Works Ltd
Priority date: 1998-07-23
Filing date: 1999-07-23
Publication date: 2000-01-26
Also published as: JP2000045156A; EP0974692A3

Abstract

A circular knitting machine (20) comprises rotary needle cylinder, knitting needles, spring jacks, selector jacks (24) and a multi-tier electrically controlled needle selecting device (30). The needle selecting device (30) includes piezoelectric elements (32) and pattern fingers (33) for selecting and causing the selector jacks (24) control the movement of the needles (22) between welt, tuck and knit positions. A pre-pusher cam (34) is provided paritally to push the selector jacks (24) inwardly before these selector jacks are engaged by the pattern fingers (33) which increases the range of selection and permits increased speed in fine gauge knitting machines (24 gauge and higher) and which permits a reduction in the number of piezoelectric elements in coarse gauge machines and the inclusion of an interlock jacquard apparatus.

Description

FIELD OF THE INVENTION

The present invention relates to circular knitting machines and, more particularly, to needle selecting apparatus therefor.

BACKGROUND OF THE INVENTION

Circular knitting machines conventionally include a rotating cylinder having vertical grooves in the outer periphery in which knitting needles are slidably mounted for movement between welt and knit positions or welt, tuck and knit positions. The spacing of the grooves, and therefore the needles, around the periphery of the cylinder is referred to as the "gauge" of the machine. Fine gauge circular knitting machines are those having a gauge of 24 or higher.
Circular knitting machines typically are equipped with needle selecting apparatus for selectively operating the needles to produce a predetermined pattern of knit stitches. One form of a-multi-tier electrically controlled needle selecting apparatus is disclosed in Japanese Publication No. 94619/1994 and an improved form thereof is disclosed in United States Patent No. 5,823,015, both of which are assigned to the current applicant.
Such needle selecting apparatus include a spring jack movably mounted in each noodle groove in the cylinder beneath the knitting needles for selectively raising the knitting needles. These spring jacks are elastic and relatively narrow so that they can be pushed inwardly and then spring back to their original position. In their original position, the spring jacks will move their associated needles to the knit position. Such spring jacks are disclosed in detail in United States Patent No. 5,647,230, also owned by this applicant. A selector jack is mounted in association with each spring jack and has a pattern butt thereon. These selector jacks are rockable radially of the needle cylinder to push the spring jacks inwardly or to permit the spring jacks to return to their original position. The selector jacks are operated by fingers activated by piezoelectric elements to engage selectively the pattern butts on the selector jacks in accordance with a pattern program in a controller.
With prior needle selecting apparatus heretofore Known, the range of selection is such that such needle selecting apparatus is limited to coarser gauge circular knitting machines or to fine gauge knitting machines operating at slower than desired speeds. For example, as illustrated in Figure 11, a fine gauge knitting machine having a gauge of 28 has a range of selection of only 1.57 mm (i.e. a width that stretches across 1.7 needles). Accordingly, there is a need for a needle selecting apparatus for fine gauge circular knitting machines that will permit such machines to be operated at faster speeds than has heretofore been possible.
Because the needle selecting apparatus is in large part mounted on the cam ring, space is limited. Heretofore, the multi-tier electrically controlled needle selecting apparatus has occupied so much of the available space that additional features, such as an interlock jacquard apparatus, could not be employed.

SUMMARY OF THE INVENTION

With the foregoing in mind, it is an object of the present invention to provide a needle selecting apparatus for a circular knitting machine which increases the range of selection and therefore permits increased speeds in even fine gauge knitting machines and which reduces the size of the needle selecting apparatus to permit additional features to the employed for coarse gauge knitting machines.
This object of the present invention is accomplished by providing a needle selecting apparatus which includes a pre-pusher cam which engages the selector jacks, before the selector jacks are engaged by the fingers activated by the piezoelectric elements, to move the selector jacks inwardly of the cylinder. Thereafter, in one embodiment, the selector jacks for the selected needles are moved further inward by pattern fingers to position the spring jacks for either the welt position or the tuck position of the knitting needles. In another embodiment, the pre-pusher earn moves the selector jacks to their innermost position and the pattern fingers engage and maintain the selector jacks in that position for the desired interval. For coarse gauge knitting machines, the pre-pusher cam permits the stack of piezoelectric elements and pattern fingers to be reduced in number and therefore, the size of the needle selecting apparatus is reduced and an interlock jacquard apparatus can also be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the present invention may be more readily understood, reference will now be made to the accompanying drawings, in which:-
Figure 1 is a fragmentary vertical section of the core part of a circular knitting machine having the needle selecting apparatus of the present invention,
Figure 2 is an enlarged fragmentary elevational view of the needle selecting apparatus of Figure 1 with the housing removed for clarity;
Figure 3 is a plan view of the piezoelectric elements of the needle selecting apparatus of this invention;
Figure 4 is a plan view, partially in section, of the pre-pusher cams of the needle selecting apparatus of this invention;
Figure 5 is a fragmentary elevational view of the cam shown in Figure 4;
Figure 6 is a fragmentary, schematic plan view of a number of the selector jacks, a pattern finger, pre-pusher cam with a conventional pattern finger shown in phantom lines;
Figure 7 is a view similar to Figure 6 of another embodiment of the present invention with a modified pattern finger;
Figure 8 is a view similar to Figure 2 of a further embodiment of the present invention in which an interlock jacquard apparatus is included;
Figure 9 is a fragmentary elevational view of the pre-pusher cam and interlock jacquard apparatus illustrated in Figure 8;
Figure 10 is a plan view, partially in section, of the interlock jacquard apparatus shown in Figures 8 and 9; and
Figure 11 is a view similar to Figures 6 and 7 of a conventional pattern finger and selector jacks.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
Referring now more particularly to the drawings and particularly to Figure 1, there is illustrated a circular knitting machine, generally indicated at 20, which includes a rotary cylinder 21 having a multiplicity of vertical grooves in the outer periphery thereof. A knitting needle 22 is slidably mounted in each groove in cylinder 21 for vertical movement between either knit and welt positions or knit, tuck and welt positions. A spring jack 23 is mounted in each groove in cylinder 21 beneath needle 22 for selectively raising the needles 22 from the welt position to the knit position or to the tuck and knit positions. A selector jack 24 is mounted in each groove of cylinder 21 beneath each spring jack 23 and is pivotable about its lower end. Such spring jacks and selector jacks are described with particularity in United States Patent No. 5,647,230 which is incorporated herein by reference.
Each selector jack 24 has a first pattern butt 24a thereon and a second pattern butt 24b. The pattern butts 24a on the selector jacks 24 are at different locations along the length of the selector jacks 24 such that the pattern butts 24a on adjacent selector jacks 24 are not in alignment. Therefore, as cylinder 21 rotates, the pattern butts 24a travel vertically spaced paths of travel to make the pattern butts 24a accessible to a multi-tier electrically controlled needle selecting device, generally indicated at 30.
Needle selecting device 30 includes a housing 31 mounted on a cam ring 25 of the knitting machine 20, and a vertical stack of spaced apart piezoelectric elements 32 (Figure 2). Piezoelectric elements 32 are mounted at one end 32a thereof on housing 31 in a cantilevered manner and have pattern fingers 33 carried by the other ends 32b thereof. Each piezoelectric element 32 is bifurcated and has two piezoelectric members 32c and 32d in parallel with separate pattern fingers 33a and 33b carried thereby. Piezoelectric elements 32 may be formed of bimorph-type ceramic elements or other piezoelectric materials that will be known to persons skilled in this art.
Pattern fingers 33 are moved up or down by the piezoelectric elements 32 either into or out of the paths of travel of the pattern butts 24a. As illustrated in Figure 2, there are eight piezoelectric elements 32 in the stack and the arrangement of the selector jacks 24 is in sets of eight with the pattern butts 24a repeating in every set of eight selector jacks. When a positive voltage is applied to piezoelectric elements 32, the pattern fingers 33 are moved upwardly out of the path of pattern butts 24a of selector jacks 24 and all of the needles 22 are moved to the knit position. When a negative voltage is applied to the piezoelectric elements 32, piezoelectric member 32c will move to position its pattern finger 33a in the path of the pattern butt 24a of its selector jack 24 to cause needle 22 to move to the welt position while a negative voltage will cause piezoelectric member 32d to cause the selector jack 24 to cause its needle 22 to move to the tuck position.
Each pattern finger 33 has a cam portion 33c at its outer end (Figure 6) with an inwardly sloping surface 33d for moving the selector jack 24 inwardly to cause its needle 22 to move either to the welt or tuck position and a linear surface 33e parallel to the path of travel of the selector jacks 24 following the sloping surface 33d to maintain the selector jacks 24 in either the welt or tuck position until the spring jack 23 is positioned at the appropriate cam track.
Needle selecting apparatus 30 includes a pre-pusher cam 34 slidably mounted in a mounting block 35 for movement between retracted (inactive) and extended (active) positions. Mounting block 35 is in turn mounted on housing 31 above the stack of piezoelectric elements 32. A spring 36 biases pre-pusher cam 34 toward its retracted position and an actuating lever 37 is pivotally mounted on block 35 for moving the pre-pusher cam 34 from the retracted to the extended position.
Pre-pusher cam 34 has a first cam portion 34a that is positioned in advance or upstream of cam portion 33c on pattern finger 33a and a second cam portion 34b that is positioned in advance of cam portion 33c on pattern finger 33b. The first earn portion 34a engages pattern butts 24b and pushes the selector jacks 24 inwardly a partial distance before the selector jacks 24 are engaged by pattern finger 33a and moved further inward to cause the needles 22 to move to the welt position. The second cam portion 34b engages the pattern butts 24a and pushes the selector jacks 24 inwardly a partial distance before the selector jacks 24 are pushed further inward by pattern finger 33b to cause the needles 22 to move to the tuck position.
To place the present invention in proper perspective, Figure 11 illustrates the operation of a typical needle selecting device having piezoelectric elements (not shown) and pattern fingers 133 and selector jacks 124. The knitting machine represented is a fine gauge knitting machine of 28 gauge (having a pitch of 0.907 mm) with eight selector jacks 124 in each set (i.e. based upon the spaced apart arrangement of the pattern butts on the selector jacks). In this set, between the first selector jack 124y and the last selector jack 124z, the pattern fingers 133 have a range of selection of 1.57 mm (i.e. a width that stretches across 1.7 needles). This narrow range of selection causes no problem with coarse gauge knitting machines (i.e. less than 24 gauge), but in the fine gauge knitting machines, such as the 28 gauge illustrated, this narrow range of selection limits the speed of the knitting machine.
Referring now to Figure 6, there is illustrated a similar 28 gauge knitting machine 20 in which the pattern finger 33a is shown in solid lines, the pre-pusher cam 34a is shown in dotted lines and the prior art pattern finger 133 is shown in phantom lines to illustrate their relative positions and mode of operation.
Prior to this invention, the pattern finger 133 had to push the selector jacks 124 inwardly between their outermost position (the knit position) to their innermost position (the welt position) to effect the needle selection. Therefore, the cam surfaces 133e on the pattern fingers 133 were much longer and engaged the pattern butts of the selector jacks 124 earlier (Figures 6 and 11).
With the present invention, the pre-pusher cam 34 pushes the selector jacks 24 partially inwardly before the pattern fingers 33 engage the selector jacks 24 much later than was heretofore possible. Therefore, the range of selection, which had been 1.57 mm (i.e. encompassing 1.7 needles), is now 4.10 mm (i.e. encompassing 4.5 needles) or 2.5 times that heretofore possible. This wider range of selection makes it possible to increase the speed of the knitting machine to provide increased production while still achieving proper needle selection.
Another advantage is that pattern finger 33 can be shorter and lighter than previous pattern fingers. Accordingly, pattern fingers 33 are more responsive.
Referring now to Figure 7, there is illustrated another embodiment of the present invention in which like elements are referred to by like reference characters with a prime notation added. A pattern finger 33' of a different configuration from that illustrated in Figure 6 is provided. Pattern finger 33' has a very short inclined or sloping surface 33d' and a longer surface 33e' parallel to the path of travel of the selector jacks 24'.
In this embodiment, the pre-pusher cam 34' pushes the selector jacks 24' fully inwardly and the linear surface 33e' is the only part of pattern finger 33' that engages and acts on the selector jacks 24'. A range of selection of 3.23 mm (i.e. corresponding to 3.5 needles) is provided and this range is twice the range provided by prior needle selecting devices. While not as large as the range provided by the needle selecting device 30, this range is large enough to provide the margin for increased speed of the knitting machine 20.
As previously stated, the present invention provides a range of selection with an extra margin. This extra margin permits a reduction in the number of piezoelectric elements in coarser gauge knitting machines which provides sufficient space for the inclusion of an interlock jacquard device. Such an embodiment is illustrated in Figures 8-10, In which like elements are referred to by like reference characters with a double prime notation added.
A multi-tier electrically controlled needle selecting device 30'' includes a vertical stack of piezoelectric elements 32'', pattern fingers 33'' and a pre-pusher cam 34'', all of which are as previously described. An interlock jacquard apparatus 40 is mounted in block 35'' so as to be slidable radially of the needle cylinder (not shown). Interlock jacquard apparatus 40 includes first and second interlock pusher cams 41 and 42 mounted for radial sliding movement between retracted and extended positions and which are biased toward the retracted (inactive) positions by springs 43 (only one of which is shown in Figure 10). Levers 37'' are pivotally mounted on block 35'' for moving the interlock pusher cams 41 and 42 from the retracted position to the extended or active position.
The interlock pusher cam 41 has an inwardly slanting or sloping surface 41a and a linear surface 41b. Interlock pusher cam 42 is of the same shape as is interlock pusher cam 41 and is therefore not shown specifically. The interlock pusher cams 41 and 42 engage additional pattern buns 24''d and 24''e on the selector jacks 24'' and on alternate selector jacks 24'', these pattern butts are at different heights from those on intervening selector jacks 24''.
When activated, interlock pusher cam 41 engages the pattern butt 24''d on a selector jack 24'' and gradually pushes it partially inwardly. Then, interlock pusher cam 42 engages the pattern butt 24''e and pushes the selector jack 24'' further inward to its innermost position.

Claims

A needle selecting apparatus for a circular knitting machine including knitting needles (22) movable between knit and non-knit positions, spring jacks (23) for moving the knitting needles (22) between such positions, selector jacks (24) for causing the spring jacks (23) to move the knitting needles (22) and a needle selecting device (30) for selecting and actuating the selector jacks (24) and including pattern fingers (33, 33', 33'') and actuating elements (32, 32''), characterized in that a pre-pusher cam (34, 34', 34'') is positioned to engage the selector jacks (24, 24', 24'') before such selector jacks (24, 24', 24'') are engaged by said pattern fingers (33, 33', 33'') and push said selector jacks (24, 24', 24'') inwardly and then the selector jacks (24) engage said pattern fingers (33, 33', 33'') whereby a wider or increased range of selection is achieved.
An apparatus according to Claim 1 wherein said pre-pusher cam (34, 34'') pushes said selector jacks (24, 24'') partially inward and said pattern fingers (33, 33'') push said selector jacks (24, 24'') further inward to their innermost position.
Art apparatus according to Claim 1 wherein said pre-pusher cam (34') pushes said selector jacks (24') to their innermost position and said pattern finger (33') engages and maintains said selector jacks (24') in said innermost position for a predetermined time interval.
An apparatus according to any of Claims 1-3 wherein said pre-pusher cam (34, 34', 34'') is internal of said needle selecting device (30).
An apparatus according to any of Claims 1-4 wherein said needle selecting device (30) is a multi-tier electrically controlled needle selecting device and wherein said actuators (32, 32'') are piezoelectric elements (32, 32'').
An apparatus according to any of Claims 1-5 wherein said actuators (32, 32'') are a plurality of pairs of parallel piezoelectric members (32a, 32b) arranged in a vertical stack.
An apparatus according to any of Claims 1-6 wherein said pro-pusher cam (34, 34', 34'') includes first and second cam portions (34d, 34e, 34''d, 34''e).
An apparatus according to any of Claims 1-7 further including an interlock jacquard apparatus (40).
An apparatus according to Claim 8 wherein said interlock jacquard apparatus (40) includes first and second interlock pusher cams (41, 42).