Three-strand Knitted Yarn

Abstract

A knitted yarn and a method and apparatus for knitting the yarn. The yarn comprises three strands arranged as two interlocked chains. Stitches in the first chain comprise first and second strands while stitched in the second chain comprise the second and third strands. Stitches in the first and second strands are formed about one reciprocating latch needle and stitches in the second and third strands are formed about a second parallel reciprocating latch needle. Each needle pulls a newly formed stitch through a preceding stitch and casts-off the preceding stitch.

Description

BACKGROUND OF THE INVENTION

This invention generally relates to textile manufacturing and more specifically to a novel yarn and a method and apparatus for manufacturing such a yarn.

Prior yarn manufacturing processes include draw-twisting, braiding and knitting. In draw-twisting, a positive feed mechanism supplies strands to a drawing area at a controlled rate. A traveller on a vertically reciprocating ring in the drawing area guides the strands onto a bobbin which rotates about a vertical axis. The combined motion of the bobbin and ring causes the strands to twist as they accumulate on the bobbin as yarn. Once the bobbin fills, an operator interrupts the process, replaces the bobbin and transfers the full bobbin to another twisting operation or final storage cone.

In braided yarn, a number of strands are interwoven or braided to form the final yarn. Two sets of feed spools counter-rotate on two tracks while paying out the strands that make up the yarn. Each spool moving in one direction passes on alternate sides of the spools moving in the other direction. As a result, each strand on one set of feed spools interweaves with all other strands from the other set.

In a prior knitting manufacturing process, two stands are deposited as alternate stitches on one or two reciprocating latch needles. As each needle reciprocates, it draws a newly formed stitch through a preceding stitch to form an interlocked yarn.

Each of the prior twisted, braided and knitted yarns has specific characteristics, advantages and disadvantages. For example, twisted and braided yarns have a substantially circular cross-section while prior knitted yarns have either a circular or rectangular cross-section. None of these manufacturing processes can produce a ribbon-like yarn.

Braided yarn has a greater breaking strength than equivalent twisted or knitted yarn (i.e. yarn with an equal weight per unit length). Prior knitted and braided yarns do not unravel and splay when cut. Twisted yarns do. Prior knitted yarns are manufactured at a much greater rate than either the twisted or braided yarns. Neither the knitted nor braided yarns have an inherent internal torque which characterizes twisted yarn, so they do not tend to kink and break in use or knit on a bias. A prior knitting machine can knit yarns of widely divergent sizes while yarn drawing and braiding machines are limited to producing a single size of finished yarn or, at most, a narrow range of sizes. Finally, braided yarns are relatively inelastic while both twisted and knitted yarns have a certain inherent elasticity.

As is apparent, no one yarn has all the foregoing characteristics. In those applications where these characteristics are desirable, a compromise is made. For example, if a yarn with a maximum strength and minimum weight is desired, a braided yarn is chosen even though it is expensive to produce and limited to a circular configuration.

Therefore, it is a general object of this invention to provide a novel knitted yarn which incorporates many advantages previously found only in different prior yarns.

Specifically, it is an object of this invention to provide a yarn which can be knitted with a thin, rectangular cross-section.

Another object of this invention is to provide a yarn which can be knitted with a breaking strength approaching that of equivalent braided yarn.

Yet another object of this invention is to provide a yarn which can be knitted to be relatively inelastic, but which is more economical to manufacture than braided yarn.

Still another object of this invention is to provide a method and apparatus for continually knitting the novel yarn at a high rate.

A further object of this invention is to provide a method and apparatus adapted for knitting the novel yarn in a wide range of yarn sizes.

SUMMARY

In accordance with this invention, our yarn comprises three strands arranged in two interlocked chains. Successive stitches in each chain comprise two strands with one strand being common to both chains.

This yarn is produced by feeding the strands to a pair of generally parallel, counter-reciprocating latch needles. As the first latch needle moves in one direction, a yarn feeding mechanism loops the first and third strands around that needle to form a stitch for the first chain. At the same time, the second latch needle pulls a first stitch previously formed in the second and third strands through a preceding stitch formed on that needle to form another portion of the second chain. The knitting machine feeds the strands to the latch needles and counter-reciprocates the latch needles to draw stitches through preceding stitches in each chain and cast off the preceding stitches to form the yarn.

Our knitted yarn has a number of important advantages. It is possible to vary the cross-section of the yarn by adjusting or varying the tension applied during the knitting operation, the spacing between the needles or the size of strands fed to the knitting machine. If, for example, the first and third strands are heavy and fed under greater tension than the second strand, the machine tends to knit a ribbon-like yarn. The effect is also produced by increasing the spacing between the needle and decreasing the tension to the second strand by increasing its feed rate. On the other hand, a yarn has a generally circular configuration when the tension on the second strand is increased or the needles are closely spaced, or both. This yarn has a breaking strength which has the same order of magnitude as braided yarn. It is significantly stronger than prior knitted yarn.

As neither the strand supply nor yarn take-up operations are involved in the knitting sequence directly, the system is capable of manufacturing yarn at significantly higher rates than those available with either draw-twisting or braiding.

This invention is pointed out with particularity in the appended claims.

A more thorough understanding of the above and further objects and advantages in this invention may be attained by referring to the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a machine for knitting yarn in accordance with this invention;

FIG. 1A is an enlarged detail view of a portion of the machine;

FIG. 2 schematically illustrates one operating sequence for forming knitted yarn;

FIG. 3 depicts the knitted yarn formed by the sequence shown in FIG. 2;

FIG. 4 schematically illustrates another operating sequence for forming knitted yarn;

FIG. 5 is a front view of the knitting machine shown in FIG. 1, partially broken away;

FIG. 6 is a side elevation;

FIG. 7 is a cross-sectional view taken along line 7--7 in FIG. 5;

FIG. 8 is a view from line 8--8 in FIG. 5; and

FIG. 9 is a machine timing diagram.

DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

A. General Discussion

In accordance with our invention, a yarn knitting machine 10 shown in FIG. 1 transforms three strands from a supply location 12 into knitted yarn which is stored at a yarn storage location 14. Generally, storage cones 16, 18, and 20 store the strands at the storage location 12. A feeding mechanism 22 draws strands 24, 26 and 28 from the cones 16, 18 and 20 through a conventional tensioning mechanism 30 for delivery to the knitting machine 10.

The feeding mechanism 22 supplies the strands 24, 26 and 28 to a single service bar 32 which deposits the strands as stitches about vertical latch needles 34 and 36. The service bar simultaneously oscillates about, and reciprocates along, a horizontal support axis to perform this function, as described later. At this point, it is merely necessary to understand that the strand 24 forms loops or stitches solely around the latch needle 34 and the strand 26 forms stitches only around the latch needle 36. The service bar 32 also alternately deposits stitches of the strand 28 around the two latch needles 34 and 36.

The latch needles 34 and 36, shown more clearly in FIG. 1A, reciprocate along spaced, vertical needle axes in a supporting needle slider block 38 below the service bar 32. The needle 34 includes a pivoted latch 40; the needle 36, a pivoted latch 42. Each time a needle reciprocates, it draws a new stitch through a preceding stitch disposed around needle stem (44 or 46) to form finished yarn 48.

The finished yarn 48 passes through a tensioning unit 50 and take-up drive assembly 52 driven by the knitting machine 10. At this point, the knitted yarn is completed and no further processing is necessary.

B. Yarn Structure and Method

FIG. 2 illustrates the sequence for forming a yarn shown in FIG. 3. In FIG. 2A, the latch needles 34 and 36 are centered on their respective needle axes with the needle 34 moving downwardly and the needle 36 moving upwardly. Latches 40 and 42 on the needles are open. Previously knitted stitches 54 and 56, each comprising two strands, lie around needle stems 44 and 46 below the latches 40 and 42 respectively.

The service bar 32, shown schematically in FIG. 2, comprises three cylindrical guides 58, 60 and 62 for the strands 24, 28 and 26, respectively. This service bar 32 has formed the stitches 54 and 56 and will form subsequent stitches about the needles 34 and 36 by depositing the strands in the directions indicated by the arrows on the individual strands. Service bar movement is such that the strands 24 and 28 form the stitch 54 while strands 26 and 28 form the stitch 56.

Still referring to FIG. 2A, the service bar 32 is centered between the needles 34 and 36 and disposed somewhat behind them. As it oscillates in the plane of the FIGURE, its arc is limited so that the outer guides 58 and 62 form stitches only about the needles 34 and 36, respectively, while the guide 60 forms the strand 28 into stitches around both needles alternately. In FIG. 2A, the service bar 32 is moving to the right in the FIGURE and has just deposited a stitch 64, comprising the strands 24 and 28, around the needle 34 above the latch 40. At this time, the service bar 32 does not form a stitch around the needle 36.

Next, as shown in FIG. 2B, the needle 34 reaches the lowest limit of travel while the needle 36 reaches its upper limit. At this time the service bar 32 is at a right-hand limit. Due to its axial motion, as described later, it has moved forward, or out from the FIGURE, so that the strands 26 and 28 now extend from the finished yarn 48 to the rear of the needle 36 and then forward above the latch 42 in front of the needle 36.

Concurrently, the latch 40 on the needle 34 has closed and captured the newly formed stitch 64, while the downward motion of the this needle has pulled the stitch 64 through the previous stitch 54 and, at its lower limit, cast the stitch 54 off. As the stitch 54 is cast-off, it forms a portion of the finished yarn 48. The tension on the finished yarn 48, produced either by its own weight or by the tensioning unit 50 (FIG. 1), assures that the stitches clear the needles 34 and 36 as they are cast off.

In FIG. 2C, the needles 34 and 36 have returned to the position shown in FIG. 2A, but the service bar 32 is at the mid-point moving to the left. In this position, the new stitch 64 formed by strands 24 and 28 lies around the stem 44 below the open latch 40. Furthermore, the service bar 32 has completely formed the strands 26 and 28 into a new stitch 66 above the open latch 42 while the stitch 56 remains formed around the stem 46 below the latch 42.

During the time interval during which the needles 34 and 36 and the service bar 32 travelled between the positions shown in FIGS. 2C and 2D, the latch 42 closed so the needle 36 pulled the new stitch 66 through the previous stitch 56 as the stitch 56 is cast-off. Simultaneously, the service bar 32 has moved to its left-hand limit and begun to form another stitch 68 with the strands 24 and 28 around the needle 34 above the latch 40.

The service bar 32 is midway between the needles and moving to the right in FIG. 2E. In this position, the needle 44 is retracting downwardly and has closed the latch 40 preparatory to drawing the next stitch 68 through the stitch 64 now formed around the stem 44.

Hence, the service bar 32 forms the strands 24 and 26 into stitches about the reciprocating axes for the needles 34 and 36. These stitches are formed alternately. As each stitch is formed, the service bar 32 also forms the strand 28 into a stitch simultaneously with one of the other strands. As a result, the strands 24 and 28 and the strands 26 and 28 form successive stitches along each of the needles with each stitch, such as the stitches 54 and 56, being pulled through preceding stitches such as the stitches 56 and 64.

The resulting yarn 48 shown in FIG. 3 comprises three strands 24, 26 and 28. The strand 24 includes stitches 54 and 64 which are formed with the strand 28 while the strand 26 comprise stitches 56 and 66 also formed with the strand 28. Each stitch passes through a preceding stitch. As a result, the strands form two chains. Successive stitches in one chain comprise the strands 24 and 28 while successive stitches in the other chain comprise strands 26 and 28. In this manner, the strand 28 interlocks the two chains so they cannot unravel.

The yarn shown in FIG. 3 has several advantages over prior yarns. First, the configuration of the finished yarn 48 can be varied by changing the relative fineness of each strand. If the strand 28 has a significantly greater cross-sectional area than the two strands 24 and 26, a circular yarn can result. On the other hand, if the strands 24 and 26 are significantly larger than the strand 28, a thin rectangular or ribbon-like yarn results. These variations can be enhanced by changing the distance between the two needle axes, or varying the tension in the strands or both.

By virtue of this knitted configuration, the finished yarn 48 does not run or splay when it is cut. As the production rate is dependent solely upon the speed of the needles and the rate at which strands are fed, production rates equivalent to the prior knitting method are attained. In addition, the number of interruptions to the process are reduced because the supply and take-up spools form no part of the process. If the strands 24 and 26 have the predominant diameter and the feed rates are adjusted so the yarn comprises a series of tight stitches, the yarn 48 is relatively inelastic and is comparable with prior braided yarns, breaking strength approaches the breaking strength for an equivalent braided yarn.

The machine in FIG. 1 can be modified so the service bar 32 deposits the strand 28 as closed loops or bights around each needle to form closed stitches. The sequence for forming the yarn with closed stitches is shown in FIG. 4. A reference numeral followed by a prime (') indicates elements which are modified with respect to FIG. 2, identical elements being referred by the same reference numerals.

Referring specifically to FIG. 4A, the needles 34 and 36 are substantially at the mid-point of axial travel with the needle 34 moving downwardly. The latches 40 and 42 are open. Previously knitted stitches 54' and 56' lie around the needle stems 44 and 46, respectively. The stitch 54' comprises the strands 24 and 28 while the stitch 56' comprises the strands 26 and 28; and the service arm has deposited a closed stitch 64' around the needle 34. As a result, the strand 28 extends from the finished yarn 48' in front of the needle 34 around the needle and crosses itself between the needles 34 and 36 as part of the closed stitch 64'. The strand 24 merely passes around the needle 34.

In FIG. 4B, the needle 34 has moved to a bottom position with the latch 40 being closed to draw the stitch 64' through the stitch 54'. The stitch 54' has been cast-off in the FIGURE. During the interval when the needles moved between the positions in FIGS. 4A and 4B, the needle 36 has moved to its upper position with its latch 42 remaining open. The service bar 32 has travelled to a right-hand limit and has deposited the strands 26 and 28 in front of the needle 36 and above the latch 42.

During the interval when the needles moved between the positions in FIGS. 4B and 4C, the service bar 32 moved to the left to a center position and completed the new stitch 66' around the needle 36. The strand 28 again extends from the finished yarn 48' to the front and around the needle 36 above its latch 42 to a position where continued motion of the service bar 32 causes the strand 28 to cross itself between the needles 34 and 36. That is most clearly seen in FIG. 4D, where the needle 36 is at its lower limit with the latch 42 closed. The stitch 56' has also been cast over the stitch 66'. At this point, the service bar 32 is depositing the strand 28 in front of the needle 34 again so that the strand 28 forms a closed loop or stitch.

Finally, in FIG. 4E, the stitches 64' and 66' lie around the stems 44 and 46, respectively. The service bar 32 has formed the strands 24 and 28 into another closed stitch around the needle 34 above the closed latch 40 and is moving in such a direction as to lay the strand 28 in front of the needle 36 to repeat the cycle shown in FIG. 4.

It is now apparent that the yarn produced by the sequences in FIGS. 2 and 4 differs in two ways. In the sequence shown in FIG. 2, the center strand 28 circumscribes both needles 34 and 36 while in FIG. 4, it circumscribes each needle separately. Secondly, in FIG. 2, stitches formed by the strands 26 and 28 are formed by passing the threads to the rear of the needle 36 before completing the stitch whereas the reverse directions are produced in FIG. 4. The modification is made by varying the rate at which the service bar 32 reciprocates above the needles as described more fully with reference to the FIGS. 5 through 9. The yarn produced according to the sequence according to FIG. 4 is basically the same as the yarn shown in FIG. 3 with these two modifications. Its advantages are similar to those advantages described or attributed to the yarn in FIG. 3.

A selection between the yarn produced by the sequences shown in FIGS. 2 and 4 depends upon several factors. These factors include the aesthetic characteristics of the finished yarn, its end use, its required strength and its stitch density. Still other factors include differences in sliding friction of the yarn and the material forming the strands.

The sequences shown in FIGS. 2 and 4 are both adapted to use strands which are twisted, braided or knitted in accordance with the prior art. Alternatively, any one or combination of the storage cones 16, 18 and 20 may contain yarn manufactured in accordance with this invention. Therefore, in the foregoing discussion, the term "strand" means any yarn component formed from fibers, filaments, or combinations of such fibers or filaments and made by prior methods or in accordance with this invention. Such strands may include both textile and non-textile materials. When knitted yarn is manufactured with strands manufactured in accordance with this invention, its relative bulk increases still further.

C. The Yarn Knitting Machine

Our yarn can be manufactured on a knitting apparatus shown in FIGS. 1 and 5 through 8. This specific knitting machine embodiment is shown for knitting only one yarn. It will become apparent during the following discussion, however, that the knitting machine may be easily adapted to knit tow yarns simultaneously.

Now referring specifically to FIGS. 5 through 8, the yarn knitting machine is disposed in a housing 100 including a horizontal support 102. A drive motor 104 mounted on the support 102 rotates a cam shaft 106 through a conventional belt and pulley system 107. The motor also drives an input shaft 108 for a torque converter 110 through another belt and pulley system 112 driven by the cam shaft 106. The torque converter 110 controls the speed of an output shaft 114. Such torque converters are known in the art, one example being a Zero-Max.sup.R torque converter, manufactured by the Zero-Max Co., Minneapolis, Minnesota. A secondary horizontal support 116 spaced above the support 102 carries the torque converter 110 so the output shaft 114 and the yarn feeding mechanism 22 are aligned. A third belt and pulley system 118 links the output shaft 114 and the feeding mechanism 22.

Strands 24, 26 and 28 may differ in size and be fed to the knitting area at different rates. The yarn feeding mechanism 22 in FIGS. 5 and 6 incorporates two feeding units 120 and 122 to supply the strands. Specifically, the feeding unit 120 supplies strands 24 and 26 at one rate, while the feeding unit 122 supplies the strand 28 at a different rate. In this specific embodiment, the third belt and pulley system 118 links both the feeding units 120 and 122 so they rotate at the same angular velocity.

With specific reference to the feeding unit 122, an idler 124 and a driving spindle 126, both of constant diameters, are mounted in parallel on a vertical support plate 128. The driving spindle 126 rotates with a shaft 130 driven by the belt and pulley arrangement 118 while another belt 132 couples the roller 124 and the spindle 126.

The strand 28 is normally wrapped about the periphery of both the idler 124 and driving spindle 126 several times before being fed to the service bar 32. As the motor 104 drives the service bar 32 and the needles 34 and 36 at constant rates, varying the angular velocity of the output shaft 114 alters the strand feed rate. That is, such a variation alters the rate at which the feeding unit 122 continuously supplies the strand 28 to the service bar 32 each time the needles 34 and 36 reciprocate.

Simultaneously, the feeding unit 120 which comprises a driving spindle 134 and idler 136 feeds the strands 24 and 26. The belt and pulley arrangement 118 also drives a shaft 138 which supports the spindle 134 while another belt 140 turns the idler 136. Variations in the speed in which the strands 24 and 26 are fed is obtained by varying the relative diameters of the roller spindles 126 and 134. In this specific embodiment, the spindle 126 has about twice the diameter of the spindle 134 to deliver the strand 28 at approximately twice the rate the strands 24 and 26.

Other types of feeding units can be incorporated in the knitting machine shown in these FIGURES. Furthermore, various guides may be interposed between the storage location 14 and the feeding mechanism 22 and between the feeding mechanism 22 and the knitting area. Such guides are known in the art and are not shown.

As previously indicated, the service bar 32 oscillates about and reciprocates along a horizontal axis simultaneously and in synchronism with the needles 34 and 36 which reciprocate along vertical axes to form the stitches. The service bar 32 and both needles 34 and 36 are driven by the motor 104 through a series of cams and levers shown in FIG. 7.

The cam shaft 106 supports two eccentric cams 142 and 144 and a pinion 146 for driving an idler gear 148 mounted on a second cam shaft 150 at twice the speed of the cam shaft 106. The shaft 150, which is vertically aligned under the cam shaft 106, carries another pair of spaced eccentric cams 152 and 154. Spacers, such as a spacer 156 located directly below the cam 144, separate the cams so each is horizontally offset from the others.

Each cam drives a lever mounted on a pivot shaft 158 parallel to and vertically aligned over the cam shafts 106 and 150. These levers are designated as a service bar lever 160, a first needle lever 162, a throw-bar lever 164 and a second needle lever 166 (FIGS. 5 and 7).

The service bar 32 is mounted on a throw-bar 168 which rides in bushings 170 and 172 located on opposite side-walls of the housing 100. An arm 174, rigidly affixed to the throw-bar 168, supports the three horizontally offset cylindrical guides 58, 60 and 62 on a lower flared portion 176 of the arm 174.

The throw bar lever 164 reciprocates the throw-bar 168 along its horizontal axis under the influence of the cam 144. Bifurcated fingers 178 and 180 on the throw-bar lever 164 support shoes 182 which engage the cam 144 at diametrically opposed portions. As the cam 144 rotates, it oscillates the throw-bar lever 164 about the pivot shaft 158. An integral upper arm 184 on the throw-bar lever 164 engages a yoke 186 with parallel upper and lower journals 188 and 190. The upper journal 188 engages the throw-bar 168 while the lower journal 190 is adapted to ride on a supporting shaft 192. Snap rings 194 in circumferential grooves on the upper throw bar 168 capture and center the yoke 186. As a result, the throw-bar 168 can oscillate about its axis in the yoke 186.

A pair of offset arms 196 and 198 couple the upper arm 184 and the yoke 186. A transverse pin 200 through the yoke 186 between the throw-bar 168 and the shaft 192, bushings 202 formed on the arms 196 and 198 and snap rings 204 provide a conventional pivotal connection between the arms 196 and 198 and the yoke 186. Therefore, as throw-bar lever 164 oscillates about the pivot shaft 158, it reciprocates the throw-bar 168 and the attached service bar. It is apparent that the throw-bar 168 can support another service bar on the opposite side of the housing so the machine can knit two yarns simultaneously.

The cam 142, the service bar lever 160 and associated linkage provide concurrent oscillating motion for the service bar 32. Shoes 206 supported by bifurcated fingers 208 and 320 on the lever 160 tangentially engage the cam 142 so the service bar lever 160 oscillates about the pivot shaft 158. An arm 212 on the service bar lever 160 extends horizontally from the pivot shaft when the lever 160 is at a middle position to engage a linkage mechanism and oscillate the throw-bar 168.

Specifically, a fixed link 214 is pivotally connected to the arm 212 by a pin 216 and to a crank 218 by another pin 220. The crank 218, in turn, rotates the throw bar lever 168 about its axis without interfering with axial motion. Such connections are known. As the cam 142 rotates and elevates the arm 206, the link 214 and the crank 218 rotate the throw-bar 168 clockwise when viewed from the service bar 32.

In this configuration with the cams 142 and 144 both mounted on the cam shaft 106, the throw bar and service bar oscillate and reciprocate at the same cyclical rate. Therefore, the service bar 32 moves substantially circularly and produces the open stitches in the yarn shown in FIG. 3.

The knitting machine is easily adapted to knit the yarn in accordance with the sequence shown in FIG. 4. The operator merely interchanges the cam 144 and the spacer 156 and moves the shoes 182 to a lower position on the arms 178 and 180. With this modification, the cam 144 rotates at twice the rate of the cam 142; and the throw-bar 168 reciprocates at twice the rate it oscillates. As a result, the service bar 32 wraps the strand 28 in a "figure 8" as closed stitches about the needles 34 and 36.

The remaining cams 152 and 144 move the needles 34 and 36 in the counter-reciprocal motion with separate, but identical needle levers 162 and 166. Referring specifically to the needle lever 162, it comprises a horizontal arm 222 which extends through an opening 224 in the housing sidewall to emerge beside the needle slider block 38 beneath the latch needle 34. An identical arm on the needle lever 166 emerges beside the needle slider block 38 beneath the latch needle 36. Each arm supports a bushing 226 in an aperture 228.

In FIG. 1A, the needle slider block 38 comprises a body portion 230 with two spaced, vertical ways 232 and 234 for supporting the stems 44 and 46 on the needles 34 and 36. The stems 44 and 46 terminate at elbows 236 and 238, respectively. Bushings 226 in the needle levers 162 and 166 individually support the elbows 236 and 238.

The needle lever 162 also comprises shoes 240 which tangentially engage the cam 152 and oscillate the needle lever 162 about the pivot shaft 158. As the bushings 228 pivotally support the needles 32 and 34, the oscillatory motion of the arm 222 on the needle 162 is translated into a reciprocal needle motion as the needles slide in their respective ways. Furthermore, the cams 152 and 154 are oppositely disposed on the cam shaft 150. As a result, the needles reciprocate at a rate which is twice the oscillating rate for the throw-bar 168 and reciprocate in opposite directions; i.e., the counter-reciprocating motion.

A still more thorough understanding of the operation of the knitting machine shown in FIGS. 1 and 5 through 8 may be obtained by additionally referring to FIG. 9 which illustrates machine timing at a reference time. As shown in FIG. 9A, the cam 152 drives the needle lever 162 starting at a mid-point with a positive-going trace of the resulting curves indicating upward displacement of the needle. Simultaneously, the cam 154 oscillates the needle lever 166 to move the needle 46 downwardly from a central reference position as represented by the dashed line. As a result, both needles reciprocate sinusoidally about a mid-point reference with respect to time at a constant rate.

FIG. 9B represents the oscillation of the throw-bar 168 and the service bar 32 with reference to a central angular position with clockwise rotation or displacement being represented by positive-going traces. As the cam 142, mounted on the upper cam shaft 106, oscillates the lever 160, the throw-bar 168 oscillates completely each time the needles reciprocate twice. As a result, the service bar 32 is centered above and between the needles when the needles are at the mid-point position.

With reference to FIG. 9C, the cam 144 is on the cam shaft 106 to knit yarn with open stitches. Reciprocation away from the housing 100 is represented by positive-going traces. In this arrangement, the lever 164 reciprocates the throw-bar 168 at the same cylical rate it oscillates. The cam 144 is oriented to retract the throw-bar 168 from a center reference position at the reference time. As the needle 34 and service bar 32 move to a limit position and return, the throw-bar 168 moves to a maximum extension. During the time the needle 36 elevates and returns to its reference point, the guide 62 travels around the needle 36 to return to is initial position. As a result, the strand 28, deposited by the guide 62 circumscribes both axes defined by needles 34 and 36.

If the cam 144 is on the shaft 150, it is oriented so the throw-bar lever 164 is at a middle position at the reference time. During the interval when the service bar 32 swings to the left and returns to the reference point, the throw-bar 168 undergoes an entire reciprocation as shown in FIG. 9D. This operation forms a complete stitch around the needle 34. Another complete stitch is formed around the needle 36 as the service bar 32 swings to the right and returns to the reference point.

As the machine knits yarn in accordance with the sequence in FIGS. 2 and 4, it drops downwardly to accumulate below the support plate 116 in FIGS. 1 and 8. A roller guide 270 pivoted on an arm 272 directs the yarn 48 to a drum 274. Another roller 276 on an arm 278 guides the yarn 48 and holds it against the surface of the drum 274. After the yarn 48 leaves the drum 274, it accumulates in a final storage location 14 which may comprise a shipping cone or other storage device.

The plate 102 supports the drum 274 and the arms 272 and 278 below the upper plate 116. A variable speed reduction unit 280, similar to the torque converter 110 and coupled to the motor 104 drives the drum 274. A belt-and-pulley arrangement 282 couples the reduction unit 280 and the motor 104 to thereby control the tension on the finished yarn in combination with the feeding mechanism 22.

In summary, our invention is directed to three related aspects of yarn manufacture. Our knitted yarn, by virtue of its construction, incorporates many advantages heretofore found only in different yarns. Specifically, the yarn does not unravel when it is cut and has no inherent torque. One yarn seems to have a breaking strength approaching that of an equivalent braided yarn. Another yarn may have a substantially circular cross-section. Alternately, tension, spacing, strand dimension, or all three can be controlled to provide a ribbon-like cross-section.

Both the knitting method and apparatus are flexible. A given apparatus can produce a wide range of yarn sizes with different types of strands with only minor modification to the apparatus. Both the method and apparatus enable production rates which are equivalent to prior knitted yarns; this rate greatly exceeds the rates available for draw-twisting or braiding.

While we have described a specific embodiment of a knitted yarn and a method and apparatus for manufacturing the yarn, many variations are possible. The illustrated method for manufacturing knitted yarn and apparatus describe specific elements to perform the various operations. Other elements may be substituted without significant degradation in the overall process. For example, the drive mechanisms move the needles in a continuous counter-reciprocating motion. The term "counter-reciprocating" is also intended to cover other types of needle motion. In some machines the needles may reciprocate in a mutually exclusive fashion to alternately form the two chains. Therefore, it is the object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of this invention.

Claims

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A knitted yarn comprising a first strand arranged in a plurality of chain stitches that define a first chain, a second strand formed separately of said first strand and arranged in a plurality of chain stitches that define a second chain, and a third strand interknitted with said first and second strands in alternate chain stitches for uniting the chains in a knitted construction.

2. Yarn as recited in claim 1 wherein said third strand interlocks successive stitches in said first and second chains.

3. Yarn as recited in claim 2 wherein said first and second chains define first and second longitudinal axes, said third strand circumscribing said first and second axes.

4. Yarn as recited in claim 2 wherein said first and second chains define first and second longitudinal axes, said third strand alternately circumscribing each axis.

5. A knitted yarn comprising three individual strands arranged in first and second chains, said first chain including a first and second strand arranged in a plurality of chain stitches, and said second chain including a third strand that is interknitted with said second strand in a plurality of chain stitches, and said second strand is interknitted alternately with the chain stitches of both chains.

6. A yarn as recited in claim 5 wherein each stitch in said first and second chains comprises said second strand.

7. A yarn as recited in claim 6 wherein said first and second chains have first and second axes, said second strand circumscribing both axes.

8. A yarn as recited in claim 6 wherein said first and second chains have first and second axes, said second strand circumscribing each axis.