Information
-
Patent Grant
-
6810694
-
Patent Number
6,810,694
-
Date Filed
Wednesday, March 5, 200321 years ago
-
Date Issued
Tuesday, November 2, 200419 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Ohlandt, Greeley, Ruggiero & Perle
-
CPC
-
US Classifications
Field of Search
US
- 066 8
- 066 125 R
- 066 131
- 066 132 R
- 066 132 T
- 066 133
- 066 146
-
International Classifications
-
Abstract
A method for circularly knitting an elastomeric yarn into a knitted fabric is provided. The method includes: operating a circular knitting machine at a machine rate, retaining a free end of the elastomeric yarn in a substantially relaxed condition, and taking up the free end into the circular knitting machine while feeding the elastomeric yarn at a first feed rate. The first feed rate maintains the elastomeric yarn in the substantially relaxed condition. The circular knitting machine continues to operate at the machine rate during the taking up of the free end.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a method for knitting an elastomeric yarn into a circularly knitted fabric.
2. Description of Related Art
It is highly desirable to incorporate elastomeric yarns into knitted fabrics intended for the creation of garments. For example, the elastomeric yarn can provide a degree of elasticity to the knitted fabric, which is useful in many garments such as socks, brassieres, panties, underwear, bathing suits, leotards, and the like.
Generally, incorporating such yarns into a knitted structure as knitted stitches, as opposed to laying-in the yarn, is difficult due to the need to knit these yarns under tension. Further, incorporating such yarns into a knitted structure as knitted stitches is particularly difficult when using circular knitting machines such as those commercially available from Santoni S.p.A. (e.g., Santoni's SM8 knitting machine).
A prime difficulty arises at the start and finish of the knitting process when the elastomeric yarn is introduced and subsequently taken out of the knitting sequence. This difficulty arises from the fact that at the finish of a knitting sequence, the elastomeric yarn has to be severed, but held under tension in readiness for reintroduction at the start of the next knitting sequence.
Prior suction holding mechanisms for nonelastomeric yarns have not proven effective for elastomeric applications. In addition, prior mechanical clamping or holding systems for holding severed elastomeric yarns have proven to be overly expensive and complex.
Difficulties are also encountered in reliably introducing the elastic yarn into the needles for take-up at the start of a knitting sequence. In order to compensate for this difficulty, it is common to slow the speed of the knitting machine. Slowing the knitting machine allows the elastic yarn to be effectively incorporated into the fabric, which has not been possible at normal machine speeds where the elastic yarn tends to pull free from the fabric.
In view of these difficulties, it is common practice to either only introduce bare elastomeric yarn at the beginning of a knitting cycle and knit bare elastomeric yarn throughout the entire cycle, or to have reduced productivity as a result of the slowed machine speeds.
However, there is a continuing desire for apparatus and methods that can provide for the selective elastomeric yarn knitting, while addressing one or more of the aforementioned deficiencies of the prior art.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for introducing elastomeric yarns into a knitting cycle in a more reliable manner than previously possible.
It is another object to provide a method for selectively knitting elastic yarns during selected parts of a knitting cycle.
These and other objects of the present invention are provided by a method for circularly knitting an elastomeric yarn into a knitted fabric. The method includes: operating a circular knitting machine at a machine rate, retaining a free end of the elastomeric yarn in a substantially relaxed condition, and taking up the free end into the circular knitting machine while feeding the elastomeric yarn at a first feed rate. The first feed rate maintains the elastomeric yarn in the substantially relaxed condition. The circular knitting machine continues to operate at the machine rate during the taking up of the free end.
A method of knitting an elastomeric yarn with a circular knitting machine is also provided by the present invention. The method includes initiating a first and a second knitting stage. The first knitting stage maintains the elastomeric yarn in a substantially relaxed condition while maintaining a free end of the elastomeric yarn in a desired position. The second knitting stage causes the circular knitting machine to take up the elastomeric yarn in the substantially relaxed condition by positively feeding the elastomeric yarn at a first feed rate. The circular knitting machine maintains the desired machine rate during the take up of the elastomeric yarn.
It is a further object of the present invention to provide a method for knitting elastomeric yarn on a circular knitting machine to produce knitted stitches of the elastomeric yarn. The method includes: retaining a free end of the elastomeric yarn in a substantially relaxed condition in readiness for introduction to needles of the circular knitting machine; introducing the free end for take-up by the needles; feeding the elastomeric yarn at a first feed rate sufficient to maintain the substantially relaxed condition of the free end during take-up by the needles; feeding the elastomeric yarn at a second feed rate to cause tension in the elastomeric yarn to be raised to a desired level during continued knitting; feeding the elastomeric yarn at a third feed rate to cause the elastomeric yarn to be regain the substantially relaxed condition; severing the elastomeric yarn to define a new tail; and retaining the new tail in the relaxed condition.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a top view of an exemplary embodiment of a circular, knitting machine according to the present invention;
FIG. 2
is a first side view of the machine of
FIG. 1
;
FIG. 3
is a second side view of the machine of
FIG. 1
; and
FIGS. 4 through 8
schematically illustrate various stages of a knitting process according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings and in particular to
FIGS. 1 through 3
, a circular knitting machine generally indicated by reference numeral
10
is illustrated. Circular knitting machine
10
has a cylinder or base
12
with a plurality of needles
14
disposed about its periphery. Machine
10
rotates needles
14
about a central axis
16
while reciprocating the needles between an upper position
18
and a lower position
20
as illustrated in phantom in
FIGS. 2 and 3
. Thus, machine
10
moves and reciprocates needles
14
to perform a knitting operation according to known principles.
Machine
10
can also receive one or more elastomeric yarns
22
from a feeding system
24
. For purposes of clarity, machine
10
is illustrated receiving only one elastomeric yarn
22
from one feeding system
24
. Of course, it is contemplated for machine
10
to have more than one feeding system, and for at least some of the feeding systems to feed more than one yarn to machine
10
.
Feeding system
24
has a guide
26
, a drive
28
, a spool or supply of yarn
30
(hereinafter “supply”), and a suction hood
32
.
Drive
28
pulls yarn
22
from supply
30
, and feeds the yarn to guide
26
. For example, drive
28
can be a servo-motor, a stepper motor, or any such motor. Preferably, drive
28
is an Elan2 (RTM). Drive
28
can be controlled by a programmable controller (not shown) of machine
10
. Alternately, drive
28
can be controlled by a programmable controller separate from, but in communication with, the controller of machine
10
.
Guide
26
is movable by machine
10
between a first position
34
(
FIG. 2
) and a second position
36
(FIG.
3
). When guide
26
is in first position
34
, it prevents yarn
22
from being taken-up by needle
14
. First position
34
of guide
26
holds yarn
22
out of reach of needle
14
, regardless of whether the needle is in its upper or lower position
18
,
20
, respectively. For example, first position
34
of guide
26
can hold yarn
22
above needle
14
as illustrated.
However, guide
26
moves yarn
22
into the path of needle
14
when the guide is in its second position
36
, which allows the yarn to be taken-up by the needle. Second position
36
of guide
26
holds yarn
22
such that needle
14
takes-up the yarn when the needle is in its upper position
18
. For example, second position
36
of guide
26
can hold yarn
22
at or below needle
14
in its upper position
18
as illustrated.
Movement of guide
26
between first and second positions
34
,
36
is illustrated by way of example only as being parallel to central axis
16
. Of course, it is contemplated by the present invention that guide
26
be movable either normal to central axis
16
or a combination of both parallel and normal to the central axis.
Suction hood
32
is disposed on base
12
in a position opposed to guide
26
. Suction hood
32
has a suction port
38
, which pulls a free end
40
of yarn
18
into the hood through the suction port. For example, suction hood
32
can evacuate air
42
to cause a negative pressure condition within the hood. The negative pressure within suction hood
32
draws air
44
into the hood at suction port
38
. The flow of air
44
into suction hood
32
pulls free end
40
into suction port
38
and, thus, maintains the free end in a desired location on base
12
.
Preferably, suction port
38
and guide
26
are radially aligned with respect to one another. In this configuration, free end
40
of yarn
22
is maintained in an optimal position with respect to needles
14
to ensure reliable introduction into the needles, when required. Preferably, suction hood
32
maintains free end
40
radially aligned with respect to the central axis
16
and perpendicular to the direction of travel of needles
14
.
The interaction of feeding system
24
with machine
10
is described in its various stages with reference to
FIGS. 4 through 8
.
In
FIG. 4
, machine
10
is performing a first stage
46
of a knitting process, which does not include the knitting of elastomeric yarn
22
. Here, base
12
is rotating and needles
14
are reciprocating such that other yarns (not shown for purposed of clarity) are being knitted in a known manner. Thus, machine
10
is operating at a desired machine rate.
During first stage
46
, drive
28
is not pulling yarn
22
from supply
30
. Free end
40
of the yarn is held in the desired position by suction hood
32
, while guide
26
is at its first position
34
such that yarn
22
is maintained out of reach of needles
14
. Accordingly, yarn
22
between drive
28
and free end
40
is in a substantially relaxed or slack condition, with the only tension being applied by the degree of suction applied by suction hood
32
. However, the amount of tension applied by suction hood
32
is sufficient to maintain free end
40
in the desired position relative to base
12
. Thus, feeding system
24
maintains yarn
22
for introduction into the knitting process, when desired.
First stage
46
outlined above may be considered to be a passive phase of the process, i.e. during this phase the elastomeric yarn is static and held in readiness for introduction into the knitting process.
A second stage
48
of the knitting process is illustrated in FIG.
5
. This is the beginning of the active phase of the process, i.e. the phase during which actual knitting of elastomeric yarn
22
is performed.
In second stage
48
, elastomeric yarn
22
is introduced to needle
14
for knitting, i.e. the second stage is the initial take-up of elastomeric yarn. In the second stage
22
, guide
26
is moved to its second position
36
to bring yarn
22
into the path of needles
14
.
Prior to free end
40
being taken-up by needle
14
, drive
28
is controlled to positively feed yarn
22
at a first feed rate. Preferably, drive
28
is controlled to begin positively feeding yarn
22
before or as guide
26
is moved to its second position
36
.
The first feed rate is selected to maintain yarn
22
at the substantially relaxed or slack condition as it is taken up by needle
14
. Thus, the first feed rate of drive
28
feeds yarn
22
at a rate substantially equal to the rate with which machine
10
is drawing the yarn into the machine. The rate with which machine
10
draws yarn
22
into the machine can depend on the machine rate and other factors, such as, but not limited to, the size and rate of rotation of base
12
, the number of needles
14
, and others. Moreover, the first feed rate of drive
28
compensates for the elastic properties of yarn
22
as it is taken up by needle
14
.
Drive
28
continues to feed yarn
22
at the first feed rate until at least one needle
14
descends to lower position
20
, allowing a knitted stitch
50
to be formed as illustrated in FIG.
8
. Knitted stitch
50
secures free end
40
in the resultant knitted fabric. For purposes of clarity, various components of feeding system have not been is illustrated in FIG.
8
.
A third stage
52
of the knitting process is illustrated in FIG.
6
. Third stage
52
represents the “normal” knitting phase of the process whereby yarn
22
is knitted into the resultant knitted fabric at a desired pre-tensioned or stretched condition.
In order to provide yarn
22
with the pre-tensioned condition in the resultant knitted fabric, drive
28
is controlled to positively feed yarn
22
at a second feed rate. The second feed rate is slower than the first feed rate and, thus, feeds yarn
22
at a rate slower than the rate with which machine
10
is drawing the yarn into the machine. In this manner, the second feed rate causes a rise in the tension of elastomeric yarn
22
between drive
28
and needles
14
to a desired “knitting” tension.
The knitting tension can be varied in yarn
22
by varying the second feed rate with respect to the rate with which machine
10
is drawing the yarn into the machine. Accordingly, the second feed rate can be a constant feed rate or can be a variable feed rate, to provide the desired knitting tension, which itself can be constant or variable within the garment.
Since third stage
52
increases the tension in yarn
22
, it is preferably initiated after the yarn has been knitted or trapped within a sufficient number of knitted stitches
50
so as to prevent free end
40
from being pulled from needles
14
upon application of the knitting tension. Thus, drive
28
is controlled to initiate third stage
52
after sufficient needles
14
have taken-up yarn
22
and moved to lower position
18
. This is indicated diagrammatically in
FIG. 5
as a distance
54
. Preferably, third stage
52
is initiated at a predetermined time delay from commencement of second stage
48
.
In order to stop knitting of elastomeric yarn
22
, it is necessary to sever the yarn with a cutter (not shown) of machine
10
. However, severance of yarn
22
can not be performed while the yarn is under its knitting tension; to do so would cause the yarn to elastically recover to its relaxed condition, causing the yarn to unthread from guide
26
so that it is not captured by suction hood
32
. Thus, a fourth stage
56
of the knitting process, illustrated in
FIG. 7
, is provided.
In fourth stage
56
, drive
28
is controlled to positively feed yarn
22
at a third feed rate. The third feed rate is chosen to maintain yarn
22
at the substantially relaxed or slack condition as it is taken up by needle
14
. Thus, the third feed rate of drive
28
feeds yarn
22
at a rate substantially equal to the rate with which machine
10
is drawing the yarn into the machine and at a rate that compensates for the knitting tension induced in the resultant fabric.
Accordingly, at the time when machine
10
severs yarn
22
, to create a new free end
40
, the yarn between drive
28
and suction hood
32
has already elastically recovered to its substantially relaxed state. Thus, due to its relaxed state, yarn
22
does not retract to unthread itself from guide
26
when severed, but instead is drawn into suction hood
32
. Substantially simultaneous with the severing of yarn
22
, fourth stage
56
controls drive
28
to stop positively feed yarn
22
, i.e. it is switched off, while guide
26
is moved back to its first position
34
. The knitting process has now progressed back into the passive phase (first stage
46
) and is ready for the next knit or knitting cycle.
First through fourth stages
46
,
48
,
52
, and
56
can be repeated as desired within the same garment. Thus, a resultant garment can be provided by the method and apparatus of the present invention that has elastomeric yarns selectively incorporated therein. Importantly, positively feeding elastic yarn
22
into machine
10
allows the yarn to be incorporated into the resultant fabric while maintaining (e.g., without slowing) the machine rate of machine
10
.
The above method and apparatus are described by example only in relation to operation on an electronically controlled circular knitting machine having a plurality of yarn feeds around a needle cylinder. A suitable machine is a SM
8
Santoni knitting machine; of course, other circular knitting machines are contemplated for use with the present invention. For such a machine, it is envisaged that each feed station would be provided with its own suction hood
32
and its own feeding system
24
.
It should also be noted that the terms “first”, “second”, “third”, “upper”, “lower”, and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated.
While the present invention has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from the scope thereof. Therefore, it is intended that the present invention not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out this invention, but that the present invention will include all embodiments falling within the scope of the appended claims.
Claims
- 1. A method for circularly knitting an elastomeric yarn into a knitted fabric, the method comprising:operating a circular knitting machine at a machine rate; retaining a free end of the elastomeric yarn in a substantially relaxed condition; and taking up said free end into said circular knitting machine while feeding the elastomeric yarn at a first feed rate, said first feed rate being sufficient to maintain the elastomeric yarn in said substantially relaxed condition, wherein said circular knitting machine continues to operate at said machine rate during said taking up of said free end so that said free end is knitted in the knitted fabric.
- 2. The method as in claim 1, further comprising feeding the elastomeric yarn at a second feed rate after said free end is knitted in the knitted fabric.
- 3. The method as in claim 2, wherein said second feed rate is sufficient to cause the elastomeric yarn to be tensioned to a desired level.
- 4. The method as in claim 2, further comprising feeding the elastomeric yarn at a third feed rate sufficient to return the elastomeric yarn to said substantially relaxed condition.
- 5. The method as in claim 4, further comprising severing the elastomeric yarn to define a new free end after the elastomeric yarn is returned to said substantially relaxed condition.
- 6. The method as in claim 5, further comprising retaining said new free end in said substantially relaxed condition.
- 7. The method as in claim 5, wherein said circular knitting machine continues to operate at said machine rate during formation of said new free end.
- 8. The method as in claim 5, wherein said free end and said new free end are retained in said substantially relaxed condition with a suction hood.
- 9. The method as in claim 5, further comprising taking up said new free end while feeding the elastomeric yarn at said first feed rate, and feeding the elastomeric yarn at said second feed rate after said new free end is knitted in the knitted fabric.
- 10. A method of knitting an elastomeric yarn with a circular knitting machine operating at a desired machine rate, the method comprising:initiating a first knitting stage, said first knitting stage maintaining the elastomeric yarn in a substantially relaxed condition while maintaining a free end of the elastomeric yarn in a desired position; and initiating a second knitting stage, said second knitting stage causing the circular knitting machine to take up the elastomeric yarn in said substantially relaxed condition by positively feeding the elastomeric yarn at a first feed rate, wherein said circular knitting machine maintains the desired machine rate during said take up of the elastomeric yarn.
- 11. The method as in claim 10, wherein said free end is maintained in said desired position by a suction hood of the circular knitting machine.
- 12. The method as in claim 10, wherein said first feed rate is substantially equal to a rate with which the circular knitting machine takes up the elastomeric yarn.
- 13. The method as in claim 12, wherein said first feed rate compensates for elastic properties of the elastomeric yarn as it is taken up by the circular knitting machine.
- 14. The method as in claim 10, further comprising feeding the elastomeric yarn at said first feed rate until said free end is secured within a resultant knitted fabric.
- 15. The method as in claim 14, further comprising initiating a third knitting stage, said third knitting stage causing the circular knitting machine to knit the elastomeric yarn within said resultant fabric at a desired pre-tensioned condition by positively feeding the elastomeric yarn at a second feed rate.
- 16. The method as in claim 15, wherein said second feed rate is slower than said first feed rate.
- 17. The method as in claim 15, wherein said second feed rate is a constant feed rate or a variable feed rate.
- 18. The method as in claim 15, further comprising initiating a fourth knitting stage, said fourth knitting stage returning the elastomeric yarn to said substantially relaxed condition by positively feeding the elastomeric yarn at a third feed rate.
- 19. The method as in claim 18, wherein said third feed rate is substantially equal to a rate with which the circular knitting machine takes up the elastomeric yarn.
- 20. The method as in claim 18, further comprising severing the elastomeric yarn to form a new free end.
- 21. The method as in claim 20, wherein said circular knitting machine maintains the desired machine rate when forming said new free end.
- 22. The method as in claim 20, further comprising maintaining said new free end in said desired position.
- 23. The method as in claim 20, further comprising repeating said first through fourth knitting stages.
- 24. A method for knitting elastomeric yarn on a circular knitting machine to produce knitted stitches of the elastomeric yarn, the method comprising:retaining a free end of the elastomeric yarn in a substantially relaxed condition in readiness for introduction to needles of the circular knitting machine; introducing the free end for take-up by the needles; feeding the elastomeric yarn at a first feed rate sufficient to maintain the substantially relaxed condition of the free end during take-up by the needles; feeding the elastomeric yarn at a second feed rate to cause tension in the elastomeric yarn to change to a desired level during continued knitting; feeding the elastomeric yarn at a third feed rate to cause the elastomeric yarn to regain the substantially relaxed condition; severing the elastomeric yarn to define a new tail; and retaining the new tail in the substantially relaxed condition.
US Referenced Citations (15)