Needle selector for knitting machine

Details Needle selector for knitting machine Needle selector for knitting machine

2000-02-18

2001-04-24

Worrell, Danny (Department: 3741)

Textiles: knitting

Independent-needle machines

Circular

Reexamination Certificate

active

06220062

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a needle selector for use in knitting machines such as circular knitting machines and weft knitting machines, and more particularly to a needle selector for use in knitting machines in which knitting needles are selected by a piezoelectric drive mechanism.
2. Description of the Related Art
In a knitting machine such as a circular knitting machine or a weft knitting machine, vertical motions of the knitting needle are selected in accordance with a knitting procedure stored in a recording medium, such as a floppy disk or the like, to knit a fabric of the desired texture. Various needle selectors are used for selecting that vertical motions of the knitting needle.
Before describing the needle selector according to the present invention, an outline of needle selection in a knitting machine will be explained with reference to a circular knitting machine schematically illustrated in
FIGS. 6A through 6C
.
FIG. 6A
shows a schematic perspective view of the basic knitting mechanism of a circular knitting machine. As illustrated in
FIG. 6A
, in the circular knitting machine, knitting needles
2
are arranged slidably in a plurality of vertical grooves (not shown) around the circumference of a knitting cylinder
1
, rotating in the direction indicated by an arrow A, the grooves being provided along the lengthwise axis of the knitting cylinder
1
. Underneath the knitting needles
2
are usually disposed needle selection jacks
12
to permit contact with the lower parts of the knitting needles
2
. On the other hand, underneath the knitting cylinder
1
is statically arranged a cylindrical cam base
15
a,
and on the upper part of that cam base are disposed a plurality of cams
15
of a prescribed shape at prescribed intervals.
The basic principle of knitting is such that each of the knitting needles
2
on the rotating knitting cylinder
1
is thrust upward via the needle selection jack
12
; a yarn loop is made by feeding yarn
5
, taken up from a yarn bobbin
6
into the hooks of a knitting needle
2
projecting from the upper face of the knitting cylinder
1
, as a result; and one stitch is formed by lowering the knitting needle
2
with a known mechanism (not shown). Therefore, a desired fabric can be knit by opting either to give a vertical motion to each knitting needle
2
or to allow advancing to the next step of knitting without forming a stitch. In order to provide such motions to knitting needles, in a knitting machine, needle selection jacks
12
are usually arranged underneath and in contact with knitting needles
2
, and the vertical motions of the knitting needles are controlled by using a needle selector
3
, operating on the basis of information from a controller
4
with a built-in knit texture memory device, to selectively engage the needle selection jacks
12
with the knitting needles
2
.
Next will be described with reference to
FIGS. 6B and 6C
, illustrating the relationship between the selection jacks and the needle selecting means, an instance in which piezoelectric bodies, which are used according to the present invention, are used as means of knitting needle selection.
A piezoelectric body
47
can be either bent in the way shown in
FIG. 6B
or in the way shown in
FIG. 6C
, reverse to the bend illustrated in
FIG. 6B
, depending on how a voltage is applied. At the tip of the piezoelectric body
47
is arranged a finger
9
linked to it. In
FIGS. 6B and 6C
, the piezoelectric body
47
, the finger
9
and a raising cam
15
are positioned within the frame of a drawing, and the knitting needles
2
and the needle selection jacks
12
move circularly together with the knitting cylinder
1
(not shown) from the top to the bottom of the frame of the drawing (or in the reverse direction). The needle selection jacks
12
can swing pivoting on fulcrums
12
a,
and in the upper part are provided needle selection butts
13
and raising cam butts
14
projecting sideways from the needle selection jacks
12
as illustrated.
When the piezoelectric body
47
is curved as shown in
FIG. 6B
, the needle selection butts
13
of the needle selection jacks
12
, which circularly move, hit the finger
9
, and the resultant thrusting of the needle selection jacks
12
in the clockwise direction, pivoting on the fulcrums
12
a,
prevents the raising cam butts
14
from engaging with the raising cam
15
of the needle selection jacks
12
. Therefore, the needle selection jacks
12
fail to be thrust upward by the raising cam
15
, and at the same time the knitting needles
2
fail to be thrust upward.
When the piezoelectric body
47
is curved as shown in
FIG. 6C
, the finger
9
at the tip of the piezoelectric body
47
does not hit the needle selection butts
13
of the needle selection jacks
12
which circularly move together with the knitting cylinder
1
, and the needle selection jacks
12
remain in the vertical direction with the result that the raising cam butts
14
at the lower ends of the needle selection jacks
12
are thrust upward along the inclined face of the raising cam
15
, the knitting needles
2
being thrust upward along with the thrust.
Selective engagement of the needle selection butts
13
of the needle selection jacks
12
with the finger
9
at the tip of the piezoelectric body
47
enables the knitting needles
2
to move upward freely as desired and thereby enables a knit fabric of any desired texture to be knit.
The single most important performance feature for knitting is high productivity, i.e. the possibility to rotate the knitting cylinder faster. In order to turn the knitting cylinder faster, it is necessary to enable the needle selector for controlling upward shifting of the knitting needles to operate faster. For this reason, various fast operating knitting needle selectors have been developed and came into use.
For instance, the same applicant as that for patent on the present invention proposed a needle selector configured to enable a plurality of fingers to be swung by an attractive or repulsive force of an electromagnet (see Japanese Patent Laid-Open No. 60-224845), which is both faster and more compact than conventional needle selectors and moreover can save electric power consumption. Further, the same applicant as that for patent on the present invention proposed a piezoelectric needle selector which causes knitting needles to be selected by operating the fingers themselves by the bending of piezoelectric bodies in place of the above-cited electromagnetic needle selector (see Japanese Patent Laid-Open No. 62-28451), which achieved further advances in speed increase, size reduction and energy saving for needle selectors.
The same applicant as that for patent on the present invention further invented an improved version of the aforementioned piezoelectric needle selector, and filed on Oct. 5, 1988 the Japanese Patent Application No. 63-249967 for that invention, entitled “Needle Selector for Knitting Machines.” This was registered as the Japanese Patent No. 1969970, and the corresponding U.S. patent application was registered as U.S. Pat. No. 5,027,619.
This improved piezoelectric needle selector is illustrated in FIG.
7
A. To describe this improved version on the basis of claim
1
of Japanese Patent No. 1969970 with reference to
FIG. 7A
, this is a knitting needle selector in which fingers
9
are arranged to be movable relative to piezoelectric bodies
7
each having a piezoelectric element; electric power is applied to the piezoelectric elements to actuate the fingers
9
; this motion of the fingers
9
causes knitting needles of the knitting machine to be selected (via needle selection jacks); and knitting of a fabric of a prescribed pattern texture is made possible. The rear end of each piezoelectric body
7
is characterized by being movably supported via a spherical body, i.e. a rotary body
20
, by a support
21
or a concave part
22
of a housing; the tip of the piezoelectric body
7
is characterized by being movably linked via a sphe

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