Method and apparatus for yarn processing position control of flat knitting machine

Abstract: In order to process yarn preliminarily, and to change over precisely at a desired knitting position, the yarn (12) fed to the flat knitting machine (10) is processed by a yarn processing device (18) and is changed over in character such as color. To change over the yarn (12) at the changeover position D on the fabric (11), it is necessary to actuate the yarn processing device (18) preliminarily at the actuating position C. The controller (21) calculates the actuating position C from the set value in the setting circuit (22) and pattern information from the memory (23), and when the encoder (16) detects that the yarn feeding position to the knitting needle has reached the actuating position C, the yarn processing device (18) is actuated. The length of the yarn from the yarn processing position A to the actuating position C is nearly equal to the sum S of the loop length for knitting from the actuating position C to the changeover position D.

Description: The invention relates to a method and an apparatus of yarn processing position control according to the preambles of the independent claims. Such a method and such an apparatus are known from EP-A-0 307 769. The method and the apparatus relate to a flat knitting machine for processing the yarn by a knotter or the like for changing over by coupling an exchange yarn with the yarn fed for knitting, and for knitting an Intarsia pattern or the like by using the processed yarn, and to apparatus for executing this method. Hitherto, when knitting Intarsia pattern or stripe pattern, colors are changed by coupling a new yarn to an existing yarn in the process of knitting by a knotter provided in the knitting machine. Such prior art is disclosed, for example, in the Japanese Examined Patent Publication JP-B2-1990-14455 (WO 82/03642) or the Japanese Unexamined Patent Publication JP-A-1988-270846 (DE-A-3712264). According to the prior art disclosed in JP-B2-1990-14455, the stripe pattern which is a stripelike pattern with changed colors is knitted by a circular knitting machine. Knitting is done by a cylindrical rotary needle, and a drum is provided between a knotter and a cylinder in order to retain yarn at an intermediate position. The peripheral length of the cylinder is constant, and the required length of the yarn is determined by the product of this length and the number of stages for knitting the stripelike pattern, and the knotter changes over the yarn when feeding the yarn by this length. While the knotter is working to change over yarn, the yarn preliminarily retained in the drum is fed to the cylinder, so that the knitting operation does not stop. According to the prior art disclosed in JP-A-1988-270846, by splicing the yarn while knitting by means of the flat knitting machine, patterns of changed colors are knitted. Where yarn splicing is desired, the knitting machine is once stopped, and the yarn is spliced at the upstream side. The yarn from the position of the yarn being fed to the knitting needle to the position exceeding the coupling point is sucked into a yarn drawing device provided at one end of the needle bed. The sucked yarn is confined, and the knitting machine is started again to resume knitting, and the drawn portion of the yarn is cut off. According to the above-mentioned prior arts, within one knitting course of fabric, a stripelike pattern without yarn changeover can be favorably knitted. However, various problems occur when knitting an Intarsia pattern fabric 1 as shown in Fig. 10. In the Intarsia pattern fabric 1, plural colors are used in one knitting course in the horizontal direction in Fig. 10. In the downward knitting course, there exist white yarn fabric 2, red yarn fabric 3, and yellow yarn fabric 4. In the upward knitting course, there exist white yarn fabric 2, blue yarn fabric 5, and yellow yarn fabric 4. In the prior art disclosed in JP-B2-1990-14455, although knitting of stripelike pattern is possible, Intarsia pattern fabric 1 cannot be knitted. In the prior art disclosed in 1988-270846, the knitting operation must be once stopped when changing over the yarns of various colors, and the yarn must be drawn out and spliced. When knitting the Intarsia pattern fabric 1 shown in Fig. 10, if using different yarn feeders for each color, problems when changing over the yarns do not occur. In this case, to knit the Intarsia pattern fabric 1, yarn feeders for four colors must be prepared. Yet, since the red yarn and blue yarn are not knitted simultaneously, by coupling the red yarn and blue yarn, it is possible to knit by using three yarn feeders in all. This idea can be applied when using more color yarns. In order that the coupling portion may come to the changeover position of the red yarn fabric 3 and blue yarn fabric 5, the knitting operation of the knitting machine may be stopped at that position, and the yarns may be changed over as in the prior art disclosed in JP-A-1988-270846. However, when drawing out and processing the yarn, the knitting operation must be stopped, and the cut portion of the yarn is a waste. Moreover, since the yarn drawing device is needed, the construction of the apparatus and the control for the apparatus are complicated. EP-A-0 307 769 discloses a knitting machine with a yarn exchange device. The machine is equipped with a yarn storage which is provided between a knotter and the yarn processing position. The length of yarn in the storage is kept constant. It is hence a primary object of the invention to present a method and an apparatus for yarn processing position control of a flat knitting machine, capable of changing over the character of yarn at an accurate knitting position, by using a pre-processed yarn, before being supplied to the knitting position. It is a further object of the invention to present a method and an apparatus for yarn processing position control of a flat knitting machine, capable of changing over the character of yarn without providing a specialized device in addition. These objects are solved in accordance with the features of the independent claims. Dependent claims are directed on preferred embodiment of the invention. A method of yarn processing position control for a flat knitting machine forms a pattern by firstly selectively processing, at a processing position A, the yarn to be fed to the flat knitting machine such that the character of the yarn is changed, to knit a fabric, characterized in comprising the steps of: preliminarily setting a yarn length AB required from the processing position A to a predetermined reference position B, and a yarn length Li consumed by each loop corresponding to a knitting operation; detecting from a pattern information for the fabric to be knitted a changeover position D on the fabric to be knitted at which the character of the knitting yarn has to change, forming the sum S with reference to the yarn length Li to be consumed by the loops from the changeover position D in an order reverse to the knitting order; determining an actuating position C on the fabric at which the sum S satisfying the condition AB + BC ≤ S, wherein BC is the yarn length from the reference position B to a yarn feeding position for the knitting needle; detecting the yarn feeding position at which the knitting yarn is fed to the knitting needle after start of the knitting operation; and processing the yarn at the processing position A when the yarn feeding position reaches the actuating position C. In the invention, the actuating position C is determined as a yarn feeding position to the knitting needle when the following condition is satisfied, AB+BC≦S+α so that unprocessed yarn being left over by not more than a predetermined length α even if knitting up to the changeover position D, and the yarn of the length α being drawn out by the knitting operation of the knitting needle at the changeover position D. The invention also relates to an apparatus for yarn processing position control for a flat knitting machine comprising yarn processing means, that changes over selectively the character of the yarn for knitting a fabric by firstly processing the yarn to be fed to the flat knitting machine at a processing position A, and a memory for storing pattern information of the fabric to be knitted, characterized in further comprising: setting means for preliminarily setting a yarn length AB required from the processing position A in the processing means to a predetermined reference position B, and a yarn length Li consumed by each loop corresponding to a knitting operation; calculating means for forming the sum (S) with reference to the yarn length Li to be consumed by the loops from a changeover position D on the fabric to be knitted for changing over the character of the knitting yarn in a direction reverse to the knitting order, according to the information stored in the memory, and for determining an actuating position C on the fabric at which the sum S satisfies the condition of AB + BC ≤ S, wherein BC is the yarn length from the reference position B to a knitting needle; detecting means for detecting the yarn feeding position which is the position of the knitting needle in the knitting operation; and control means for controlling, in response to the outputs from the calculating means and the detecting means, the yarn processing means so that the yarn being processed by the yarn processing means when the yarn feeding position reaches the actuating position C during knitting operation. In the invention, the calculating means calculates the actuating position C as a yarn feeding position to the knitting needle in the condition of AB+BC≦S+α so that the unprocessed yarn being left over by not more than a predetermined length α even if knitting up to the changeover position D; and the control means controlling the knitting operation of the knitting needle to draw out the yarn of the length not more than α after knitting up to the changeover position. The invention furthermore relates to another apparatus for yarn processing position control for a flat knitting machine comprising yarn processing means for selectively changing over the character of the yarn for knitting a fabric by firstly processing the yarn to be fed to the flat knitting machine, characterized in comprising: operating input means for entering an actuating position C on the fabric which is the yarn feeding position to the knitting needle at the timing point for changing over the character of the knitting yarn, and a position D on the fabric to be knitted at which the character of the yarn of the fabric changes; and control means which, in response to the input to the operating input means,control the flat knitting machine so as to start processing of the yarn by the yarn processing means when the yarn feeding position reaches the actuating position C during knitting operation, and so as to draw out the yarn of a predetermined length α by knitting operation of knitting needle when the yarn feeding position during knitting operation reaches the changeover position D. According to the invention, the yarn length AB required from the processing position A for processing the yarn and the predetermined reference position B, and the yarn length Li consumed by every loop corresponding to the knitting operation such as knitting, tucking and missing are set preliminarily. From the pattern information of every loop to be knitted, the changeover position D on the fabric for changing over the knitting yarn to the thread after-processed yarn is determined, and the yarn length Li consumed by every loop is added reversely to the order of knitting from the changeover position D, and the sum S is calculated. The actuating position C is determined as the yarn feeding position, supposing the length of the yarn required from the reference position B to the yarn feeding position for the knitting needle as BC, when the following relation AB+BC≦S is satisfied. After start of knitting operation, the position of the knitting needle to which the yarn is supplied is detected, and when the yarn feeding position reaches the actuating position C, the yarn is processed at the processing position A. In the process of summing the consumed yarn length Li reversely to the order of knitting from the changeover position D, initially the sum S is shorter than the length (AB + BC) of the yarn from the yarn feeding position for the knitting needle to the processing position A. The length of AB is constant, and the length of BC varies with the yarn feeding position. When the condition in formula (5) is satisfied for the first time, it is designed to process the yarn at the processing position A, and therefore after further continuation of knitting up to the changeover position D, the processed portion of the yarn preliminarily processed at the actuating position C is fed to the knitting needle. The knitting after changeover position D, is performed by using the yarn changed in character by the processing, and therefore the required number of yarn feeders does not increase if plural yarns are used. In a preferred embodiment of the invention, the yarn is processed at the actuating position C satisfying the relation of AB+BC≦S+α when the unprocessed yarn may be left over by not more than the predetermined length α at the changeover position D. At the changeover position D, the yarn in the length of α is drawn out by the knitting operation of the knitting needle. When the length α is determined, for example, at more than the maximum error that may occur when summing the consumed yarn length Li, the yarn being drawn out always includes the processed portion, and therefore knitting after the changeover position D is able to be done by using the changed yarn. As a result, the yarn may be changed over accurately. According to the invention, moreover, the yarn to be fed to the flat knitting machine is preliminarily processed by the yarn processing means, and the character of the yarn for knitting the fabric is changed over. The device for controlling the yarn processing position includes setting means, memory, calculating means, detecting means and control means. In the setting means, the length AB of the yarn from the processing position A in the yarn processing means to the predetermined reference position B, and the yarn length Li consumed by every loop corresponding to the knitting operation such as knitting, tucking and missing are set. In the memory, the pattern information of the fabric to be knitted is stored in every loop. The calculating means sums the consumed yarn length Li set for each loop from the changeover position D on the fabric for changing over the knitting yarn to the thread after-processed yarn. When the sum S satisfies the relation of AB+BC≦S in terms of the set yarn length AB and the yarn length BC required from the reference position B to the yarn feeding position for the knitting needle, the yarn feeding position to the knitting needle is calculated as the actuating position C. The detecting means detects the knitting needle position during the knitting operation. The control means actuates the process of yarn by the yarn processing means when the yarn feeding position reaches the actuating position C during knitting operation, in response to the outputs from the calculating means and detecting means. The sum S and the yarn length from the yarn processing position A to the actuating position B become equal to each other, and therefore the character of the yarn is able to be securely changed over at the changeover position D. In other preferred embodiment of the invention, the yarn is processed at the actuating position C when the unprocessed yarn is left over by not more than the predetermined length α at the changeover position D and the relation of AB+BC≦S+α is satisfied, and it is controlled to draw out the yarn in the length of α at the changeover position D by the knitting operation of the knitting needle. For such knitting operation, for example, adjacent needles are available if they are not in operation. When the length α is determined at more than the maximum error when adding the consumed yarn length Li, the yarn being drawn out always includes the processed portion, so that the yarn is able to be changed over accurately. According also to the invention, the actuating position C and changeover position D are entered in the operating means. The control means controls so as to start processing of yarn by the yarn processing means when the yarn feeding position reaches the actuating position C during knitting operation, and to draw out the yarn in the predetermined length α by the knitting operation of the knitting needle when the yarn feeding position reaches the changeover position D. As the actuating position C, when the yarn feeding position where the length of the unprocessed yarn is not more than α when the yarn feeding position reaches the changeover position is entered, the yarn is able to be changed over accurately at the changeover position D. Thus, in the invention, since processing of yarn is started at the yarn feeding position to the knitting needle when the sum S of the consumed yarn length from the changeover position D to the actuating position C is more than the yarn length from the yarn processing position A to the actuating position C, the character of yarn is able to be changed over securely when the fabric knitted by the fed yarn reaches the changeover position D. Hence, using few yarn feeders, many types of yarns can be changed over and used. The invention also allows accurate changeover of the character of yarn at the changeover position D on the fabric. Moreover, the yarn in the length of α is drawn out by the knitting operation of the knitting needle, and therefore any particular device for drawing out is not additionally required. As a knitting operation, there are possibilities of the tuck operation to be fed with the yarn to the hook of the needle and of the knit operation to be fed with the yarn over the already fed yarn. Moreover, it is possible to feed the yarn on the back of the needle, or to bury the drawn out yarn under the transferred loops after the transfer operation. According to the invention, when the yarn is processed by the yarn processing means at the moment the knitting needle reaches the actuating position C during knitting, the character of yarn can be changed over securely when the knitting of the fabric reaches the changeover position D. As a result, using few yarn feeders, many yarns can be changed over and used, so that a variety of fabrics may be knitted. Furthermore, in the invention, at the changeover position D on the fabric determined from the pattern information to be knitted, the yarn in the predetermined length α is drawn out by the knitting operation of the knitting needle, so that the yarns' may be changed over accurately. Also according to the invention, when the actuating position C and the changeover position D are entered in the operating means, the control means changes over the character of yarn at the actuating position C, and it is controlled so that the yarn in the length of α is drawn out by the knitting operation of the knitting needle at the changeover position D. By setting the actuating position C so that the length of the unprocessed yarn may be α or less when the knitting operation reaches the changeover position D, accurate changeover of yarn is achieved on the fabric. BRIEF DESCRIPTION OF THE DRAWINGS Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein: Fig. 1 is a front view showing a schematic constitution of an embodiment of the invention. Fig. 2 is a front view of an Intarsia pattern fabric 30 that can be knitted by the embodiment shown in Fig. 1. Fig. 3 is a block diagram showing an electric constitution of a controller 21 shown in Fig. 1. Fig. 4 is a schematic front view showing the constitution for processing of yarn 12 in the embodiment in Fig. 1. Fig. 5 is a flow chart showing the processing in the embodiment in Fig. 1. Fig. 6 is a front view showing a schematic constitution of other embodiment of the invention. Fig. 7 is a schematic perspective view showing the knitting operation of a flat knitting machine. Fig. 8 is a diagram showing the operation of a cam device 70 in a flat knitting machine. Fig. 9 is a diagram showing an error absorbing operation in a further different embodiment of the invention. Fig. 10 is a diagram showing an example of Intarsia pattern fabric 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now referring to the drawing, preferred embodiments of the invention are described below. Fig. 1 shows a schematic constitution of an embodiment of the invention. A flat knitting machine 10 knits a fabric 11 by using a yarn 12. Knitting is effected by reciprocating motion of a carriage 15 in the lateral direction in Fig. 1, on a needle bed 14 disposed on a frame 13. The position of the carriage 15 is detected by an encoder 16. The yarn 12 is supplied from plural cones 17 disposed above the needle bed 14. Plural yarns supplied from the cones 17 are processed by a yarn processing device such as knotter and splicer, and are changed in their character, such as color and thickness. The knotter is a device for binding and coupling different yarns. The splicer is a device for twisting different yarns end to end together for linking without forming knot. The yarn drawn out from the yarn processing device is provided with a tension by a yarn tension device 19, and is supplied for knitting through a yarn feeder 20. The control for knitting the fabric 11 by the flat knitting machine 10 is executed by a controller 21. The controller 21 comprises a setting circuit 22 for presetting a yarn length AB required between a yarn processing position A and a reference position B which is set at one end of the needle bed 14, and a yarn length Li consumed by every loop corresponding to control information containing stitch density and kind of knitting operation such as knitting, tucking and missing, and a memory 23 for storing the knitting pattern information in every loop. The controller 21 controls the carriage 15 according to the stored data in the memory 23, and knits the fabric 11. To change over the yarn 12 at the changeover position D of the fabric 11, it is necessary to actuate the yarn processing device 18 at the actuating position C prior to the changeover position D. The controller 21 calculates the actuating position C according to the set value in the setting circuit 22 and the stored data in the memory 23, and changes over the yarn when the yarn feeding position to the knitting needle determined from the position of the carriage 15 detected by the encoder 16 reaches the actuating position C. Fig. 2 shows an Intarsia pattern fabric 30 knitted by the embodiment shown in Fig. 1. The Intarsia pattern 30 comprises a first color yarn fabric 31, a second color yarn fabric 32, and a third color yarn fabric 33. These fabrics 31, 32, 33 are knitted by different knitting courses, concerning the knitting course in the horizontal direction, and are changed over at changeover positions D1 and D2. As a result, the third color yarn fabric 31, second color yarn fabric 32, and third color yarn fabric 33 can be knitted by using a same yarn feeder 20. As the entire Intarsia pattern fabric 30, by using two more yarn feeders 20 for knitting fourth color yarn fabric 34 and fifth color yarn fabric 35 furthermore, it can be knitted by a total of three yarn feeders. The portion of rib stitch 36 is knitted in any color. Thus, the Intarsia pattern fabric 30 can be knitted by three yarn feeders 20. If using different yarn feeders 20 for all colors, five yarn feeders 20 must be used. To change over the colors at changeover positions D1, D2, the yarn is processed by the yarn processing device 18 in Fig. 1 when the knitting needle reaches the predetermined actuating positions C1, C2. Fig. 3 shows the constitution of the controller shown in Fig. 1. The controller 21 comprises, aside from the setting circuit 22 and memory 23, an operation circuit 40, an input circuit 41, and a control circuit 42. In the setting circuit 22, the position information of devices and loop length Li as consumed yarn length are set. In the stitch knitted by missing, actually loop is not formed, but its consumed yarn length is also explained as a loop length for the sake of convenience. In the memory 23, the knitting data and pattern information are stored. The carriage position signal from the encoder 16 shown in Fig. 1 is given to the input circuit 41. The operation circuit 40 which is realized by a microcomputer and others leads out a yarn processing signal to be given to the yarn processing device 18 when the carriage reaches the actuating position C, in response to the outputs from the memory 23 and input circuit 41, and issues an error processing signal when reaching the changeover position D, thereby knitting so as to absorb the error. Fig. 4 and Fig. 5 respectively show configuration and processing when changing over the yarns in the Intarsia pattern fabric 51. In Fig. 4, the Intarsia pattern fabric 51 is composed of base fabric 52 and pattern 53, which are knitted by different yarns from the different yarn feeders 20. When the front end of the knitting needle 20a knitting the pattern 53 reaches the changeover position D, the yarn fed from the yarn feeder 20 is changed over to the yarn processed by the yarn processing device 18. For this purpose, while knitting the actuating position C, it is necessary to change over the yarn preliminarily at the processing position A. When the pattern 53 is small, the actuating position C may be outside of the pattern 53. The reference position B is, for example, the left end of the needle bed 14 shown in Fig. 1. In Fig. 5, by setting the reference position B on the basis of the pattern information and knitting data, processing is started from step s1. At step s2, point D or the changeover position is calculated from the pattern information. To knit pattern 53 from point D in reverse direction of actual knitting, the point knitted by the knitting needle n needles before is supposed to be point Cn. Supposing the yarn length consumed corresponding to the knitting operation and loop at point Cn to be loop length Ln, the loop length data preset in the setting circuit 22 is referred to. At step s4, the sum S of loop length and parameter n are initialized to zero. At step s5, using the pattern information, the length of the yarn required from the reference position B to the point Cn is calculated. At step s6, the length AB of the yarn required from the yarn processing position A to the reference position B among set values is calculated. At step s7, AB and BCn are summed up. At step s8, the value of Ln is added to S. At step s9, it is judged whether relation of formula (9) is satisfied or not. S≧AB+BCn If the condition is not satisfied at step s9, the operation goes to step s10 and then returns to step s5, At step s10, the value of n is increased by 1 only. In this way, when repeated from step s5 to step s9, the value of n is increased by 1 each time, and it becomes far from the changeover position D in the reverse direction from actual knitting. When the condition of step s9 is satisfied, going to step s11, the actuating position C advanced from the changeover position D by K which is the value of the parameter n at that time, and the processing is terminated at step s12. Incidentally, K is the minimum value of n for satisfying formula (9). Since the value of AB is constant, step s6 can be omitted by calculating it at step s1. Fig. 6 shows the constitution of other embodiment of the invention. This embodiment is similar to the embodiment in Fig. 1, and corresponding parts are identified with the same reference numbers. What should be noted here is that first yarn length measuring device 54A, yarn pool 55, and second yarn length measuring device 54B are provided between the yarn processing device 18 and yarn tension device 19. The yarn length measuring devices 54A, 54B detect the length of the supplied yarn by the output from the rotary encoder, which is attached to the roller dislocated angularly as the yarn 12 is supplied from the yarn processing device 18 and yarn pool 55. The yarn pool 55 retains the yarn in the length corresponding to the difference of measurements by the yarn length measuring devices 54A and 54B, and feeds the retained yarn 12 to the yarn feeder 20 when processing the yarn by actuating the yarn processing device 18. Fig. 7 shows the knitting operation in the flat knitting machine. The knitting needle 56 dislocating along the needle groove of the needle bed is moved by the cam device in the carriage, and is dislocated as indicated by N1 to N13. A hook 57 is formed at the front end of the knitting needle 56, and is opened or closed by a latch 58. A loop 60 being formed as the yarn 12 is fed from the yarn feeder 20 possesses a loop length from loop end 61 to loop end 62 per loop. This loop length is determined by the amount of suction by the knitting needle into the state of N12 or the like. Fig. 8 shows a cam device 70 disposed on the carriage for knitting by the knitting needle 56. The cam device 70 comprises a raising cam 71, a center cam 72, a raising cam 73, a knitting cam 74, guard cam 75, and a knitting cam 76, and makes a butt 56B of the knitting needle 56 to be moved up and down. The raising cams 71,73, and knitting cams 74, 76 are provided in each set of right and left side, and they have their own role corresponding to the carriage moving direction shown by arrow 77. When the carriage advances to the left side in Fig. 8, the knitting needle 56 is pulled up by the raising cam 71, and is pulled down by the knitting cam 76. The knitting cams 74,76 can be dislocated in the stitch density adjusting directions indicated by arrows 78, 79, respectively, and the stitch density is adjusted depending on the pull-down extent of the knitting needle 56. This stitch density adjustment may be remote-controlled by the pulse motor. Since the loop length can be changed by the stitch density adjustment of the knitting cams 74, 76, and if the length of the yarn 12 measured by the yarn length measuring device 54, and the theoretical value which is the sum S calculated from the pattern information are different, the stitch density of the knitting cams 74, 76 may be adjusted and corrected. Fig. 9 shows a further different embodiment of the invention. An Intarsia pattern fabric 80 is knitted of four patterns 81, 82, 83, 84. The pattern 81 and pattern 82 are knitted by changing over the yarns at point D. At point D, preliminarily considering the maximum value of error, an unprocessed yarn in a length of α or less is left over. The method for processing yarn of this length α is thought about in various way. An example is to be knitted by using the knitting needle 56 which is not used in design knitting, as for pattern 81, and is detached off the knitting needle 56 after knitting of the course, or by knitting and processing by tucking the knitting needle in the midst of use in design knitting, the error portion including the knot 85 which is the processing portion in the fabric 80 may be absorbed. When the length of α corresponds to the distance k needles, the error of length α can be absorbed by using the needle k/2 apart from the position D. At this time, the knot 85 is knitted into the loop so as not be visible from the outside as a product. Such knitting process may be prepared as the subroutine of the controller 21 shown in Fig. 1, and may be selected depending on the pattern to be knitted. In this embodiment, instead of formula (9), the yarn is processed at the actuating position C where the following formula (10) is satisfied. S+α≧AB+BCn Incidentally, even in the flat knitting machine not provided with full functions of the controller 21 shown in Fig. 3, accurate yarn changeover is possible if having the functions as input circuit 41 for operating and entering the actuating position C and changeover position D, and the control circuit 42 for controlling to change over the yarn in response to the input circuit 41. That is, at the changeover position D, the yarn in length α is drawn out and processed by the knitting operation of the knitting needle as mentioned above. The actuating position C is determined, for example, (1) by calculating with the aid of a CAD system or the like other than knitting machine, (2) by calculating from the loop length on the basis of the knitting design by the operator, or (3) by making a trial knitting without calculating and predicting by observing the location of the knitted portion. At this time, taking error into account, when designed to leave the unprocessed yarn only by the length of a or less at the changeover position D, accurate yarn changeover is enabled on the fabric. In the foregoing embodiments, different yarns are tied or spliced by using knotter or splicer as the yarn processing device 18, but the invention is similarly applied in other processing, such as change of property of same yarn. Moreover, the knitting pattern is not limited only to the Itarsia pattern but also to the stripe pattern or the like, whatever requires yarn to be changed over for color change or the like. A needle to use for processing the above-mentioned yarn of length α is available, if the needle is not used for Garment knitting within the width of the fabric, in which a knitting pattern exists inside the fabric like the dia pattern of the Intarsia pattern. A plurality of needles are also able to be used. Further, different method is possible, for example, as tucking to needles in use for pattern knitting. It is possible to use needles existing outside the fabric width when knitting pattern is formed over the fabric width as in stripe patterns. The present embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and the range of equivalency of the claims are therefore intended to be embraced therein.

Claims: A method of yarn processing position control for a flat knitting machine, which forms a pattern, by firstly selectively processing, at a processing position A, the yarn (12) to be fed to the flat knitting machine (10) such that the character of the yarn is changed, to knit a fabric (11), characterized in comprising the steps of: preliminarily setting a yarn length AB required from the processing position A to a predetermined reference position B, and a yarn length Li consumed by each loop corresponding to a knitting operation; detecting from a pattern information for the fabric to be knitted a changeover position D on the fabric to be knitted at which the character of the knitting yarn has to change, forming the sum S with reference to the yarn length Li to be consumed by the loops from the changeover position D in an order reverse to the knitting order; determining an actuating position C on the fabric at which the sum S satisfies the condition AB + BC ≤ S, wherein BC is the yarn length from the reference position B to a yarn feeding position for the knitting needle; detecting the yarn feeding position at which the knitting yarn is fed to the knitting needle after start of the knitting operation; and processing the yarn at the processing position A when the yarn feeding position reaches the actuating position C. The method of claim 1, wherein the actuating position C is determined when the following condition is satisfied: AB + BC ≤ S + α, so that unprocessed yarn of not more than a predetermined length α is left over even if knitting up to the changeover position D, and the yarn of the length α is drawn out by the knitting operation of the knitting needle at the changeover position D. An apparatus for yarn processing position control for a flat knitting machine comprising yarn processing means (18), that changes over selectively the character of the yarn for knitting a fabric (11) by firstly processing the yarn (12) to be fed to the flat knitting machine (10) at a processing position A, and a memory (23) for storing pattern information of the fabric to be knitted, characterized in further comprising: setting means (22) for preliminarily setting a yarn length AB required from the processing position A in the processing means (18) to a predetermined reference position B, and a yarn length Li consumed by each loop corresponding to a knitting operation; calculating means (40) for forming the sum (S) with reference to the yarn length Li to be consumed by the loops from a changeover position D on the fabric (11) to be knitted for changing over the character of the knitting yarn in a direction reverse to the knitting order, according to the information stored in the memory (23), and for determining an actuating position C on the fabric at which the sum S satisfies the condition of AB + BC ≤ S, wherein BC is the yarn length from the reference position B to a knitting needle; detecting means (16) for detecting the yarn feeding position which is the position of the knitting needle in the knitting operation; and control means (42) for controlling, in response to the outputs from the calculating means (40) and the detecting means (16), the yarn processing means (18) so that the yarn being processed by the yarn processing means (18) when the yarn feeding position reaches the actuating position C during knitting operation. The apparatus of claim 3, wherein the calculating means (40) determining the actuating position C when the following condition is satisfied: AB + BC ≤ S + α, so that a unprocessed yarn of not more than a predetermined length α is left over even if knitting up to the changeover position D; and the control means (42) controls the knitting operation of the knitting needle to draw out the yarn of the lengtn of not more than α after knitting up to the changeover position. An apparatus for yarn processing position control for a flat knitting machine comprising yarn processing means (18) for selectively changing over the character of the yarn for knitting a fabric (11) by firstly processing the yarn (12) to be fed to the flat knitting machine (10), characterized in comprising: operating input means (41) for entering an actuating position C on the fabric which is the yarn feeding position to the knitting needle at the timing point for changing over the character of the knitting yarn, and a position D on the fabric to be knitted at which the character of the yarn of the fabric changes; and control means (42) which, in response to the input to the operating input means (41), control the flat knitting machine so as to start processing of the yarn by the yarn processing means (18) when the yarn feeding position reaches the actuating position C during knitting operation, and so as to draw out the yarn of a predetermined length α by knitting operation of knitting needle when the yarn feeding position during knitting operation reaches the changeover position D.

Inventors: MORITA TOSHIAKI, NISHITANI HIROKAZU, MORITA, TOSHIAKI, NISHITANI, HIROKAZU
Applicants: SHIMA SEIKI MFG, SHIMA SEIKI MFG., LTD.
Application year: 1993
Main classification: D04B7
IPC codes: D04B15, D04B7