Double layer sock and method of making

A double layer sock is formed on a circular knitting machine so that the inner layer and the outer layer are connected by knit stitches adjacent the toe portion and the inner and outer layer wales adjacent such connection are aligned. A section of knit courses is formed beyond the connected toe portion of both the inner and outer layer as an inner guide segment, an inner clip, an outer guide segment, and an outer clip, with each guide segment formed at a lower stitch density than either the toe portion or the clip that border the guide segment.

FIELD OF THE INVENTION 
The present invention relates to socks, and more particularly to double 
layer socks for athletic use and a method of making the same. 
BACKGROUND OF THE INVENTION 
Socks provide comfort, insulation and protection to the feet of the wearer. 
Socks are produced in a variety of styles to serve numerous functions, 
including dress, casual, and athletic, with additional variations achieved 
through use of different yarns and patterns. 
Athletic socks are used in many activities, such as in walking, tennis, 
basketball, and skiing, all of which can cause the feet to perspire and be 
fatigued or injured. It has long been recognized that by increasing the 
thickness of the sock, perspiration is more effectively absorbed and any 
impact from the athletic activity is cushioned. 
Socks are almost universally made by knitting on what is known in the trade 
as a circular knitting machine. A circular knitting machine knits a 
tubular fabric structure through the controlled actions of a multiplicity 
of latch needles and sinkers on a length of yarn. A typical circular 
knitting machine in use today is a Lonati 454 J machine, made by the 
Lonati Company, S.P.A. of Brescia, Italy. The Lonati 454 J machine has 108 
latch needles that are located circumferentially around its needle 
cylinder. The knitting action as well as the stitch density is controlled 
through a program of instructions installed on a microprocessor. This type 
of machine also incorporates a dial plate with hooks as later referred to. 
Single, as well as double layer socks are generally knit with a rim 
surrounding an opening at the leg portion and an opening at the toe 
portion. The toe opening of a machine knit sock is typically closed in a 
separate operation performed on a model 222 Complett automatic sewing 
machine made by Conti Complett, S.P.A. of Milan, Italy. The Complett 
sewing machine has a guide with a slot through which its operator passes a 
relatively thin fabric segment adjacent the toe opening of the sock. The 
sewing machine has a pair of opposed gripper chains that move the sock 
through a trimming section to remove the fabric that is beyond the 
relatively thin segment and then through a sewing section to close the 
sock toe seam. 
Traditional means of increasing the thickness of socks involves producing a 
pair of socks with a terry layer such as that disclosed in U.S. Pat. No. 
3,796,067 to East in which the sock has a smooth knit layer and a terry 
layer. The '067 patent teaches forming the sock by knitting of an elongate 
tube and inverting one half within the other half to achieve two layers. 
Socks made with partial multiple layers are disclosed in U.S. Pat. No. 
4,431,096 to Safrit et al. which shows a sock having a triple layer fabric 
in the foot portion; and U.S. Pat. No. 4,467,626 to Coble et al. which 
shows a sock with a double layer in the foot portion. Socks made with a 
full multiple layer are also disclosed in U.S. Pat. No. 4,571,290 to Hursh 
et al. which shows a two-ply athletic sock with low-friction interface 
surfaces; and U.S. Pat. Nos. 5,675,992 and 5,778,702 to Wrightenberry 
which show double layer socks and methods of making such socks. 
Double layer socks of the kind described above provide the desired multiple 
layers, but have the disadvantage of requiring a relatively large labor 
component to produce, resulting in higher prices to the consumer or lower 
profit for the manufacturer. Many of these double layer socks are closed 
at the toe by sewing the toe of the inner layer closed and then sewing the 
toe of the outer layer closed, in which case the inner and outer toe 
sections are not connected, leading to bunching, twisting and other causes 
of discomfort to the wearer. Alternatively, the inner and outer toes are 
closed together by manually aligning the knitting wales of the two layers 
to avoid the undesired twisting, but increase the time and cost to 
manufacture. 
A further method of construction of a double layer sock is disclosed in 
U.S. Pat. No. 4,958,507 to Allaire et al. The method of the '507 patent 
begins with the step of knitting a sock with a first course that is 
transferred to a transfer plate (also known as a dial plate) to remain in 
standby while the balance of the double layer sock body is knitted. The 
retained first course is then transferred from the dial plate at the end 
of the knitting process to form a connection between the inner layer and 
the outer layer at the toe. When the inner and outer layers are connected 
at the toe, additional courses are knit to form a single tubular terminal 
layer that extends beyond the two sock layers. The method of the '507 
patent overcomes the alignment and twisting problem noted above, but fails 
to provide what is later referred to as a low stitch-density "guide" 
fabric which enables the toe seam to be efficiently closed. 
The object of the invention is thus to provide an improved method for 
producing a double layer sock and an improved sock produced by such 
method. Other objects will become apparent as the description proceeds. 
SUMMARY OF THE INVENTION 
The invention provides a double layer sock and method of making in which 
the inner toe and the outer toe are integrally stitched closed with 
respective inner and outer wales aligned. The sock inner layer is knit 
with a first tubular segment of normal stitch density (this segment being 
referred to as the "clip") and a second tubular segment of low knit 
density (this segment being referred to as the "guide segment") and then 
the balance of the sock body is knit with normal stitch density to 
complete the inner layer of the sock. The knitting continues with an outer 
layer of the sock joined to the inner layer along a fold line and having 
normal stitch density, a third tubular segment of low knit density (a 
"guide segment"), and a final tubular segment of normal knit density (a 
"clip"). The inner and outer toe portions are maintained with their wales 
in alignment by holding the first tubular segment on a transfer dial plate 
as the balance of the knitting is completed and then the respective second 
and third tubular "guide" segments of each layer are connected by knitting 
a series of bridge stitches. The sock is then discharged from the knitting 
machine and transferred to a toe closing sewing machine. In the toe 
closing operation which is facilitated by the presence of the guide 
fabric, the toe is seamed by sewing through the fabric of both layers 
inward of the guide segment after the clip has been removed. 
An improved double layer sock is achieved both at less cost to manufacture 
and with greater comfort for the wearer due to eliminating the bunching 
and twisting referred to above.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 illustrates a completed double layer sock 10 that has been knitted 
by the method of the invention including tubular outer layer 12 and 
tubular inner layer 14, connected at the top by the folded fabric portion 
designated rim 16. As used herein, the terms outer layer and inner layer 
are used to describe the respective layers of sock blank 10B (FIG. 2) as 
it is knit, which may not agree with the layer positioning as the complete 
sock 10 (FIG. 1) is worn. Double layer sock 10 has leg portion 20 that is 
contiguous with heel portion 22 which in turn is contiguous with foot 
portion 24 and which in turn is contiguous with toe portion 26. As will be 
described below, toe portion 26 of sock blank 10B is formed on the 
circular knitting machine with toe opening 44 (FIG. 2) that is 
subsequently closed by a later described sewing operation to form toe 
closure seam 28. 
The example described as the preferred embodiment herein relates to a 
conventionally shaped sock with a formed heel pocket and a formed toe 
pocket to achieve the traditional "L" shape and to position the toe 
closure seam on the top of the toe portion. However, it should be 
understood that the novel principles of the present invention pertain 
equally to what is known as a "tube sock," having a substantially 
straight, tubular shape through the leg and foot portions, with no 
machine-formed heel or toe pocket. Additional sock configurations, such as 
a sock having a formed heel pocket and a straight toe, etc., are similarly 
contemplated by the invention. 
Referring now to FIG. 2, double layer sock blank 10B of the invention is 
shown in its completely knitted condition before toe closure seam 28 of 
FIG. 1 has been made. For purposes of description, double layer sock blank 
10B is illustrated in an orientation with its toe portion 26 near the top 
as it is formed on the knitting machine. As noted above, sock blank 10B 
comprises toe portion 26, foot portion 24, heel portion 22, and leg 
portion 20. The uppermost part illustrated is toe opening 44, below which 
appears the knitted fabric portion referred to as "clip" 40 of normal 
stitch density and contiguous knitted fabric referred to as "guide 
segment" 42 of low stitch density, examples of which are given later. A 
dashed line 34 is imposed on sock blank 10B to illustrate the position at 
which stitching will be done to close toe opening 44. 
Referring now to FIG. 3, a partial section of double layer toe portion 26 
and outwardly adjacent guide portions 42, 42' and clips 40, 40' is shown 
in enlarged cross sectional view. Outer layer 12 is seen in close 
proximity to inner layer 14 at the near side and far side F of sock blank 
10B, separated by toe opening 44. Clips 40, 40' having normal density 
stitching are connected to the respective layers 12, 14 of toe portion 26 
by guide segment 42, 42' of low stitch density. Also to be noted in FIG. 3 
is that outer layer 12 is connected to inner layer 14 by bridge stitches 
46 formed on the knitting machine and passed through the inner boundary of 
the respective guide segment 42, 42'. It is the presence of the stitched 
together guide segments 42, 42' which has been found to greatly enhance 
the efficiency of the toe closing operation. 
FIG. 4 schematically illustrates circular knitting machine 50 in cross 
section. Circular knitting machine 50 includes annular needle cylinder 52 
through which the tubular fabric structure being knitted passes. A dial 
plate 62 is positioned concentrically adjacent the upper end of needle 
cylinder 52. Dial plate 62 has a number of hooks 64 oriented radially and 
distributed evenly around the periphery of dial plate 62. Each hook 64 is 
extended or retracted by a controllable mechanism, for example a pneumatic 
cylinder (not shown). The circular knitting operation is performed by the 
alternate hooking and shedding of yarn loops by a series of latch needles 
54 positioned around needle cylinder 52 and interacting with a respective 
series of sinkers 56, as is known. 
Referring further to FIG. 4, the method of the invention first involves 
knitting yarn 60 through the actions of needles 54 and sinkers 56 around 
needle cylinder 52 to form inner layer 14, beginning with its respective 
clip 40' that is formed as a first plurality of courses, for example 16 
courses. The courses comprising clip 40' are formed of a normal stitch 
density, for example 12.6 stitches per centimeter (32 stitches per inch). 
Next, knitting continues at a lower stitch density, for example 3.1 
stitches per centimeter (8 stitches per inch) to form a series of courses 
referred to as guide segment 42', for example, four courses. At the 
completion of knitting the respective courses comprising guide segment 
42', the knitting resumes at a normal stitch density. After a further one 
or more courses, beyond those courses comprising guide segment 42', are 
knit, hooks 64 extend from dial 62 and pick up the knit portions of inner 
layer 14 to hold it in reserve. The balance of inner layer 14, comprising 
toe portion 26, foot portion 24, heel portion 22, and leg portion 20 is 
knit with normal stitch density. The relative degree of normal and lower 
stitch density is disclosed as an example and is not to be construed as a 
limitation of the scope of the invention. By providing courses in the 
respective guide segments 42, 42' with lower stitch density than in 
bordering clips 40, 40' and toe portion 26, guide segments 42, 42' become 
readily positionable in the slot guide of the trimming and sewing machine 
employed for the closure of toe seam 28 (see FIG. 1) to greatly facilitate 
the toe closing operation and make it more efficient than past practice 
with socks of different construction. 
At the completion of knitting inner layer 14, the operation continues to 
knit outer layer 12 through the sequential formation of leg portion 20, 
heel portion 22, foot portion 24, and toe portion 26. During the entirety 
of the sock knitting process, the portion of sock blank 10B held on hooks 
64 drapes downwardly from dial plate 62 and then upwardly to contact 
needle cylinder 52 adjacent needles 54 and sinkers 56 as depicted in FIG. 
4. 
The next step is to release inner layer 14 from hooks 64 and interknit 
bridge stitches 46 (FIG. 3) to join inner layer 14 and outer layer 12. 
Since inner layer 14 has been held in fixed position by radially disposed 
hooks 64, the wales making up inner layer 14 and the wales making up outer 
layer 12 adjacent toe opening 44 are aligned with one another without the 
need of manual intervention. 
The knitting operation then proceeds to knit a further guide segment 42 at 
lower switch density and extending outwardly from bridge stitches 46. Upon 
completion of knitting guide segment 42, clip 40 is knit at normal stitch 
density during which inner layer 14 and outer layer 12 remain connected to 
one another by means of bridge stitches 46. At the completion of knitting 
clip 40 of outer layer 12, the knitting operation is done and sock blank 
10B is released to drop through needle cylinder 52 to a receptacle (not 
shown). 
After sock blank 10B has been released, it is inverted and transferred to a 
sewing machine, such as the Complett machine identified above, where toe 
closure seam 28 is formed to complete sock 10 as seen in FIG. 1. In this 
operation, guide segment 42, 42' is placed into the slot in the sewing 
guide of the Complett machine and gripped by its drive chains. As the 
drive chains move sock blank 10B, clips 40, 40' are trimmed off and the 
toe portion of the inner layer and outer layer is stitched to form the toe 
seam 28 as seen in see FIG. 1. The now completed sock 10 is then 
re-inverted so that toe seam 28 is hidden within. As previously stated and 
what is important to recognize is that the forming of toe closure 28 is 
greatly facilitated by the presence of connected together low 
stitch-density guide segment 42, 42' with the end result being both a 
reduction in the labor component required to make the double layer sock 
and a double layer sock characterized by the absence of bunching and 
twisting in the toe seam area. Similar benefit would be obtained by sock 
10 of the invention with the toe seam formed and kept on the exterior of 
sock 10. 
As will be understood by those skilled in the art, double layer socks can 
be knit according to the present invention with the use of various types 
of yarn in various weights. The selection of natural or synthetic yarn, 
textures, and patterns is dependent on the anticipated use to which the 
socks may be put. 
The detailed description of a preferred embodiment of the invention sets 
forth the best mode contemplated by the inventor for carrying out the 
invention at the time of filing this application and is provided by way of 
example and not as a limitation. Accordingly, various modifications and 
variations obvious to a person of ordinary skill in the art to which it 
pertains are deemed to lie within the scope and spirit of the invention as 
set forth in the following claims.