Europaisches Patentamt J European Patent Office © Publication number: 0 652 314 A1 Office europeen des brevets

EUROPEAN PATENT APPLICATION

© Application number: 94117387.4 Int. CI 6 D04B 9/06

@ Date of filing: 04.11.94

® Priority: 04.11.93 JP 301323/93 Takatsuki Osaka (JP) @ Date of publication of application: Inventor: Igarashi, Yoshiaki 10.05.95 Bulletin 95/19 10-16, Shinwadai 1-chome Kobe, © Designated Contracting States: Hyogo (JP) DE ES GB IT Inventor: Hayashi, Kiyoshi 1-20-801, Motoyamanaka-cho 1-chome, © Applicant: PRECISION FUKUHARA WORKS, Higashinada-ku LTD Kobe, 1- 5, Honjo-cho 1-chome, Hyogo (JP) Higashinada-ku Inventor: Ueda, Naganori Kobe, 4-3, Kofusa-cho Hyogo 658 (JP) Kashihara, Nara (JP) @ Inventor: Sawazaki, Masatoshi 2- 4, Tenjin-cho 1-chome, Suma-ku © Representative: Naumann, Ulrich Kobe, Patentanwalte Hyogo (JP) Ullrich & Naumann, Inventor: Shibata, Takao Gaisbergstrasse 3 2-25, Tenno-cho, D-69115 Heidelberg (DE)

© Method and apparatus for adjusting the stitch length on a circular machine.

© A method of and circular (20) for producing a knit fabric having more uniform stitches including feeders (76) feeding a plural- ity of (Y) to stitch forming instrumentalities, the spacing of which affects stitch length and which is subject to change during operation of the knitting machine, a sensor (86) for sensing the tension in the plurality of yarns which changes with changes in the spacing of the stitch forming instrumentalities, and generating a signal indicative of the average tension 00 in the yarns, a comparator for comparing the sensor signal with a pre-set desired tension, a convertor for CM m converting the comparison result into a drive signal, CO and an adjuster adjusting the spacing of the stitch forming instrumentalities responsive to the drive sig- nal.

Rank Xerox (UK) Business Services (3. 10/3.09/3.3.4) 1 EP 0 652 314 A1 2

Field of the Invention tween the upper end of the needle cylinder and the periphery of the dial. Compensating structural The present invention relates to members are provided as supports for the dial and machines and more particularly to such circular needle cylinder which thermally expand and con- knitting machines in which the stitch length in the 5 tract at the same rate as the knitting components. knit fabric is adjusted responsive to changing con- Such correlation between the rates of thermal ex- ditions. pansion and contraction requires that the com- pensating structural members be machined with Background of the Invention very high precision to extremely close tolerances. io Such manufacturing procedures are quite costly In circular knit fabrics, it is highly desirable to and difficult. have the stitch loops as uniform as possible. Var- ious changeable conditions substantially affect the Summary of the Invention stitch loops being formed on a circular knitting machine. Examples of such changeable conditions 75 With the foregoing in mind, it is an object of are the tension in the yarns being fed to the the present invention to provide a method and knitting instrumentalities and the spacing between apparatus for adjusting stitch loops being formed the upper end of the needle cylinder and the sinker by a circular knitting machine having multiple yarn cap in a single knit circular knitting machine or the feeding stations automatically responsive to chang- dial in a double-knit circular knitting machine. 20 ing conditions that affect such stitch loops. Generally, the stitch loops being formed by a This object is accomplished in one embodi- circular knitting machine are adjusted by a movable ment of the present invention by providing a ten- support for the stitch cams which is moved by an sion detecting means for detecting the tension in eccentric screw or rotating cam. Once the position the knitting yarns being fed to the knitting ele- of the stitch cam support is adjusted, the screw or 25 ments. The tension detecting means generates a cam is stopped by a stop means. With such adjust- signal indicative of the tension detected and trans- ment devices, the movement of the screw or rota- mits that signal to a control means. The control tion of the cam is conducted artificially by a me- means compares the tension signal to a desired, chanic or fixer and is not conducted automatically pre-set value and generates a driving signal based responsive to changing conditions. 30 upon the result of that comparison. The driving Recently, it has been proposed to adjust the signal is directed to an elevating means which stitch cam support by means of a rotary actuator. raises or lowers the stitch cam holder to control the However, the rotary actuator is too large for a length of the stitches and thusly provide a higher knitting machine having multiple yarn feeding sta- quality knit fabric. In a double knitting machine, dial tions. 35 needle stitch cam support ring adjusting means Further, it has been previously proposed in may be provided to adjust the dial needles respon- United States Patent No. 5,018,370 to provide a sive to the drive signal to control the length of central stitch length controlling apparatus for a cir- those stitches. cular knitting in which an elevating means vertically Alternatively, in a second embodiment, a sens- adjusts the stitch cam support ring to vary the 40 ing means for sensing the size of the gap between length of the stitch loops being formed. However, the upper end of the needle cylinder and the sinker the elevating means is manually operated and is cap or the dial periphery can be provided. The not responsive to changing conditions. sensing means creates a signal and transmits the In all of these prior stitch adjustments, the same to a control means. The control means com- stitch cam is stopped at a certain position when the 45 pares the signal from the gap sensing means with stitch adjustment is made. Therefore, variations in a pre-set value and generates a drive signal which the tension in the yarns being fed induced by the raises or lowers the dial or cap accordingly. inertia of the components of the knitting section and their thermal expansion and contraction are not Brief Description of the Drawings considered. Consequently, knitting flaws tend to 50 occur, resulting in less fabric quality than is desired Some of the objects and advantages of the and extremely poor productivity. present invention having been stated, others will One prior proposal contained in Japanese Pat- appear as the description proceeds when consid- ent Laid Open No. 195386 of 1993 does take ered in conjunction with the accompanying sche- dimensional variation of the knitting machine com- 55 matic drawings, in which: ponents caused by thermal expansion or contrac- Figure 1 is an elevational view of a circular tion into account. This proposal attempts to com- knitting machine having multiple yarn feeding pensate automatically for variations in the gap be- stations;

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Figure 2 is a fragmentary schematic view of the thereof. A mounting plate 32, in the form of a ring, core of the knitting section of the knitting ma- mounts the cam holder 31 for vertical adjustment chine shown in Figure 1; on a guide ring 33. Guide ring 33 is mounted on Figure 3 is a vertical sectional view taken sub- the machine bed 24 by a plurality of bolts 34, only stantially along line 3-3 in Figure 2; 5 one of which is shown. Guide ring 33 has a plural- Figure 4 is an enlarged fragmentary sectional ity of upstanding guide pins 35, only one of which view of the medial portion of Figure 3; is shown, mounted thereon near the inner periph- Figure 5 is an enlarged fragmentary sectional ery thereof (Figures 3 and 4). Mounting plate 32 view taken substantially along line 5-5 in Figure has a plurality of holes 36 therethrough which re- 3; io ceive the upper end portions of the pins 35 therein Figure 6 is an enlarged fragmentary sectional to hold mounting plate 32 against rotation while view illustrating the spatial relationship between permitting vertical movement thereof relative to the the needle cylinder and sinker cap in a single pins 35 and guide ring 33 (Figure 4). knit circular knitting machine; Elevating means 40 for adjusting the vertical Figure 7 is a view similar to Figure 6 of the is position of the mounting plate 32, the cam holder spatial relationship between the needle cylinder 31 and thus the cams 30 relative to the guide ring and the dial of a double knit circular knitting 33 and needle cylinder 21 is provided on mounting machine; plate 32 and guide ring 33. The elevating means Figure 8 is a sectional view of the lower portions 40 preferably comprises a plurality of simulta- of the needle cylinder, stitch cams and cam 20 neously driven screw jacks, approximately six (6) in support and elevating means of a circular knit- number, equally spaced around the mounting plate ting machine in accordance with the present 32 and guide ring 33 and each including an inter- invention; nally threaded nut 41 mounted on mounting plate Figure 9 is a fragmentary sectional view of the 32 by bolts 42 and a clamp member 43. An exter- knitting section of a double knit circular knitting 25 nally threaded screw member 44 is rotatably machine incorporating the present invention; mounted on the guide ring 33 by a sleeve bearing Figure 10 is a fragmentary elevational view of 45, a washer 46 and a bolt 47. The shank portion the drive unit of a positive yarn feeder taken 44a of the screw 44 penetrates through the bearing substantially along line 10-10 in Figure 1; 45 and has the washer 46 mounted on the lower Figure 11 is a schematic view of a control de- 30 end thereof by the bolt 47. Screw 44 has a shoul- vice in accordance with the present invention; der 44b between the threaded portion and the and shank portion 44a thereof. The shank portion 44a Figure 12 is a schematic block diagram of a flow of the screw 44 is slightly longer than the bearing chart in the method of the present invention. 45 to permit limited axial or vertical movement of 35 the screw 44 relative to the guide ring 33. A Detailed Description Of the Illustrated Embodi- sprocket 48 is mounted on each screw member 44 ments in driving relation thereto. The teeth of the sprocket 48 mate with the links of a sprocket chain 49 Referring now more specifically to the draw- mounted for rotation on a race portion 33a of the ings, there is illustrated in Figure 1 a circular knit- 40 guide ring 33 (Figures 2 and 4). ting machine generally indicated at 20. Knitting One of the screw members 44 has a drive machine 20 may be either a single knit circular means 50 operatively connected thereto (Figure 8). knitting machine or a double knit circular knitting Drive means 50 includes a reversible drive motor machine 20" in accordance with this invention. 51, which through a gear reduction unit 52, includ- In a single knit circular knitting machine 20, 45 ing gears 52a-52h, drives a shaft 53 drivingly there is a needle cylinder 21 having vertical mounted on the upper end of the screw member grooves in the outer periphery thereof in which are 44. In this manner, drive motor 51 rotates the one slidably mounted cylinder needles 22. Needle cyl- screw member 44 which rotates the one sprocket inder 21 is supported and driven in rotation by a 48. The one sprocket 48 rotates the sprocket chain ring gear 23 which in turn is supported on a knit- 50 49 which in turn rotates the sprockets 48 of the ting machine bed 24 by a wire race ball bearing 25 remaining screw jacks to raise or lower the cam (Figure 3). Ring gear 23 is driven by the knitting holder 31 and concomitantly the stitch cams 30. machine drive (not shown) in conventional manner. In the single knit circular knitting machine 20, A plurality of stitch cams 30 are supported on sinkers 60 operate in association with the cylinder a cam holder support 31 for controlling the vertical 55 needles 22 in forming the stitches. Sinkers 60 are sliding movement of the cylinder needles 22. Cam mounted for sliding radial movement relative to the holder 31 surrounds the cylinder 21 (Figure 2) and needle cylinder 21 by a sinker dial 61. The sinkers mounts the stitch cams 30 on the inner periphery 60 are moved outwardly and inwardly by sinker

3 5 EP 0 652 314 A1 6 cams 62 carried by a sinker cap 63 which in turn is used as the detecting load cell 86. Other types of supported by a cap ring 64 (Figure 3). The cap ring load cells may be used and would be known to 64 is mounted on a plurality of support stanchions those skilled in this art. 65 carried by guide ring 33 and equally spaced Alternatively to the above described tension therearound. 5 detecting means 80, a plurality of yarn tension A plurality of yarn carrier ring supports 70, sensors may be used to sense the tension in the preferably from four (4) to six (6) in number, are individual yarns and the outputs of two or more of mounted on the cam holder mounting plate 32 and those sensors averaged by an arithmetic unit and extend upwardly and outwardly therefrom to free the results thereof transmitted to the control means upper ends. The upper ends of the yarn carrier ring io 90. Further, a sensor that detects stitch quantity or supports 70 mount a yarn carrier ring 71. Alter- length variation caused by thermal expansion or natively, carrier ring supports 70 may be mounted contraction or other positional variations in the spa- on the sinker cap ring 64 instead of the cam holder tial relationship of the upper end of the needle mounting plate 32. cylinder 21 to the sinkers 60 in the single knit A plurality of mounting blocks 72 are sus- is circular knitting machine 20 (Figure 6) or the dial of pended from the yarn carrier ring 71 by bolts 73. A a double knit circular knitting machine 20" (Figure corresponding number of yarn feed fingers 74 are 7) may be used. As shown in Figure 6, the dis- suspended from the mounting blocks 72 which tance A from the top of the cylinder needle 22 to have yarn feeding orifices 75 therein for feeding the stitch drawing top edge 60a of the sinker 60 yarns Y to the needles 22. The yarns Y are fed to 20 determines the length of each stitch formed. That the yarn fingers 74 by positive yarn feed means 76 distance is subject to change by thermal expansion of conventional construction (Figure 1). and contraction and by other factors. Similarly, as Yarn tension detecting means 80 is provided illustrated in Figure 7, the distance or space B between the yarn fingers 74 and the positive yarn between the top of cylinder needle 22" and the top feed means 76 (Figures 2 and 3). Detecting means 25 of needle cylinder 21"; the distance or space C 80 preferably includes a circular ring member 81 between the top of the needle cylinder 21" and the rotatably mounted by bearings 82 on a plurality of top of dial 112; and the space D between the hook mounting members 83, preferably four (4) to six (6) of dial needle 113 and the periphery of dial 112 all in number. Mounting members 83 are mounted on affect the stitch length in knitting machine 20". The yarn carrier ring 71 by bolts 84. Circular ring mem- 30 distance sensor (later described) generates a signal ber 81 has a plurality of yarn guide apertures or which is transmitted to control means 90. Still fur- orifices 85 therein equal in number to the number ther, a temperature sensor that measures tempera- of yarn fingers 74 and positive yarn feed means ture fluctuations in the knitting section and converts 76. Each aperture 85 has a yarn guide 85a of such temperature fluctuations into stitch length wear-resistant material, such as ceramic or por- 35 variations signals could be employed. celain, therein (Figure 5). Referring to Figure 1 1 , the signal from load cell The yarn guides 85 in circular ring member 81 86 is transmitted to a wave forming device 91 are positioned such that the yarns Y change direc- which forms a part of control means 90. The signal tion or bend as they pass through the guide ap- is converted to a wave form in the wave forming ertures 85. Accordingly, changes in the collective 40 device 91, amplified in an amplifier 92 and then or average tension in the yarns Y will cause the entered into a comparator 93. At the same time, circular ring member 81 to rotate in one or the the amplified wave form is converted into a tension other direction. A position detecting switch means indication and displayed by a tension display or load cell 86 is provided beneath the circular ring means 94. Comparator 93 includes a first setting member 81 for detecting changes in the position of 45 means 93a and a second setting means 93b. The the ring member 81. A bracket 87 is mounted on first setting means 93a pre-sets the desired knitting the lower side of ring member 81 in position to yarn tension, such as, for example, four grams, and contact the actuator 86a of load cell 86. A spring the second setting means 93b pre-sets the permis- 88 biases the bracket 87 and thus ring member 81 sible variation from the pre-set desired tension, toward the actuator 86a of the load cell 86. The 50 such as, for example, ± one gram. The setting load cell 86 generates an electrical signal upon any means 93a and 93b are illustrated as being analog change in the position of ring member 81 and devices. It should be readily apparent, however, transmits that signal to a control means 90 (Figure that digital devices could be used instead of these 1). analog devices. A commercially available load cell, Type TC 55 The comparator 93 compares the wave-form 5R5K with a rated capacity of 5 kgf from TEAC signal with the pre-set desired tension set by first Electronic Measuring Co., Ltd. in Kawasaki City, setting means 93a and the permissible variation set Japan, which is of the compressed type, can be by second setting means 93b and transmits the

4 7 EP 0 652 314 A1 8 comparison results to a converter 95. If the average column 102 and thus the dial 112 and cam holder tension detected exceeds or falls below the pre-set 114. Drive means 120 includes a reversible drive value by more than the permissible variation, the motor 121 and a gear reduction unit consisting of converter 95 generates a drive signal to motor 51 gears 122a-122h. Gear 122h drives a shaft 123 on to raise or lower the stitch cam holder 31 by an 5 the upper end of which is a drive pinion 124 which amount to compensate for the increased or de- meshes with gear teeth on the periphery of female creased tension and to correct the yarn tension to nut 115. Accordingly, when drive means 120 the desired value. rotates the female nut in one direction, the dial The control means 90 will function in the same support column 102, dial shaft 104, dial hub 110, manner regardless of whether the input signal io dial 112 and dial cam holder 114 will be raised and comes from a load cell, a distance sensor or a vice versa. temperature sensor. The control means 90 can The yarns YJ are fed by positive feed means receive and process an input signal indicative of a (not shown) to feed fingers 130 carried by support change in any condition that affects stitch length. blocks 131 mounted on the outer periphery of dial Referring now to Figure 9, another embodiment is cam holder 114. The feed fingers 130 direct the of the present invention will now be described, in yarns YJ to the cylinder needles 22" and the dial which like components will be referred to by the needles 113. Intermediate the positive feed means same reference characters with the prime notation (not shown) and the feed fingers 130, the yarns YJ added. A double knit circular knitting machine is pass through yarn guides 85a" in a circular mem- generally indicated at 20" and includes a needle 20 ber 81" rotatably mounted by bearings 82" on a cylinder 21" having cylinder needles 22" slidably support member 132 which in turn is mounted on mounted in grooves in the periphery of cylinder the hub portion 102b of the dial support column 21". Cylinder 21" is mounted on ring gear 23" which 102. in turn is rotatably mounted on bed 24" by bearing A distance sensor 133 is mounted on the lower 25". Cylinder needle stitch cams 30" are supported 25 end of the top bed portion 101a by an adjustable by a cam holder 31". Cam holder 31" is supported bracket 134. Distance sensor 133 includes an ac- by a mounting plate 32" mounted for vertical ad- tuator 133a which projects downwardly into contact justment on a guide plate 33" by elevating means with the hub portion 102b of the dial support col- 40'. umn 102. The distance sensor 133 remains station- Suitable stanchions 100 on bed 24" support a 30 ary and senses variations in the vertical position of top bed 101 above the needle cylinder 21". Top the dial support column 102 and thus the dial 112 bed 101 includes a vertical column portion 101a in and dial needles 113 relative to the upper end of which is mounted for vertical adjustment a dial the needle cylinder 21". Distance sensor 133 gen- support column 102 having a vertical, cylindrical erates a signal indicative of the effect of such portion 102a and a horizontal, circular hub portion 35 distance variations on stitch length and transmits 102b. Rotatively mounted in support column 102 that signal to the control means 90. by bearings 103 is a dial shaft 104 which is driven The circular member 81" and yarn guides 85a" in rotation by a top gear 105. Top gear 105 is cooperate with a load cell (not shown) which op- driven by the knitting machine drive (not shown) in erates exactly like load cell 86 to detect variations conventional manner. 40 in the tension in yarns YJ and to transmit such A dial hub 110 is fixedly mounted on the lower signals to the control means 90. end of dial shaft 104 by bolts 111. A rotary dial 112 Referring now to Figure 10, there is illustrated is anchored to the upper peripheral portion of the a drive means 140 for driving the positive yarn dial hub 110 and rotates therewith. Dial 112 has feed means 76. Drive means 140 includes a timing radial grooves in the upper surface thereof in which 45 pulley 141 at the lower end of an input shaft of a dial needles 113 are slidably mounted. stepless transmission 142. Transmission 142 may Dial needle stitch cams (not shown) are sup- be of any suitable type, such as Type RX 400 by ported in contact with the dial needles 113 by a Simpo Industry, Kyoto, Japan, with a control sys- dial cam holder 114 which is fixed to the hub tem, such as Type LR 2A by Simpo Industry, portion 102b of dial support column 102. The up- 50 Kyoto, Japan. per end portion of dial support column 102 has Transmission 142 is shifted by a pilot motor screw threads 102c thereon and these threads 143 and drives an output shaft 144. Drive gears 102c mate with internal threads of a female nut 115 145, 146 are fixed to output shaft 144 and mesh stationarily mounted on top bed 101, but rotatable with gears 147, 148 mounted on a pair of shafts relative to top bed 101 and dial support column 55 150, 151. Pulleys 152a, 152b and 153a, 153b are 102. respectively mounted on the shafts 150, 151 and A drive means 120 is provided for rotating the are convertible in the diametrical direction. Pulleys female nut 115 to raise and lower the dial support 152a, 152b, 153a and 153b drive the positive yarn

5 9 EP 0 652 314 A1 10 feeder 76, which may be of the MPF Type by tected to obtain an average tension variation for Memminger in Germany, by means of an endless stable stitch adjustment. For example, if the yarn belt (not shown). In the commercially available feeding tension of the individual yarns is four drive mentioned above, the revolutions per minute grams and a hundred yarns is fed to the knitting of the output shaft 144 are not displayed, but it is 5 needles, then a maximum of 400 grams of load preferable to do so by means of a magnetic sensor should be detected by the load cell 86. If, however, or a tachogenerator and a display means. the load cell detects a load of 550 grams, then the Further, if a desired knitting yarn feed (rotating average tension is 5.5 grams and the average speed of the pulley) is entered into a separately tension exceeds the permissible variation by 0.5 of established known control device (see, for exam- io a gram and adjustment is necessary. ple, Japanese Patent Publication No. 17460 of Furthermore, a comparison means that senses 1981), it is converted to revolutions of the output the yarn feeding speed and detects deviations shaft 144 by an arithmetic unit. Then, the dif- therefrom is provided. The yarn feeding speed can ference between the converted revolutions and the then be changed by a stepless transmission in detected revolutions can be compared to output is accordance with the detected deviation while the the corresponding signal to pilot motor 143 in ac- knitting machine is in operation. Heretofore, such cordance with the difference. Other variations of adjustments were possible only while the knitting drive means 140 will be readily apparent to per- machine was stopped. sons skilled in this art. By combining the automatic stitch adjustment Referring now to Figure 12, there is illustrated 20 and the yarn feeding speed adjustment, various a flow chart of the control method in accordance knitting settings in a circular knitting machine can with the first embodiment of the present invention. be smoothly and automatically changed. First, in step 1 , the program determines whether or In the drawings and specifications, there has not the knitting machine is in operation. If the been set forth a preferred embodiment of the in- answer is "No," the program proceeds to alternate 25 vention, and although specific terms are employed, step 2 and stops the drive motor 51. If the answer they are used in a generic and descriptive sense is "Yes," the program proceeds to step 3 and only and not for purposes of limitation. determines whether or not the measured value of the current knitting yarn feeding tension is larger Claims than the set value plus the allowable variation 30 therefrom. If the answer is "Yes," the program 1. In a circular knitting machine including knitting proceeds to step 4 and reverses the direction of instrumentalities for forming stitches to pro- drive motor 51. If the answer is "No," then the duce a knit fabric, certain of said knitting in- program proceeds to step 5 wherein it is deter- strumentalities being arranged in a predeter- mined whether or not the measured value of the 35 mined spatial relationship, the length of the yarn feeding tension is less than the set value stitches being determined by the spatial rela- minus the allowable variation. If the answer is tionship between said knitting instrumentalities "Yes," the program proceeds to step 6 and starts and such spatial relationship being subject to the drive motor 51. If the answer is "No," the being changed by several factors encountered program proceeds to step 7 and stops the drive 40 in the operation of said knitting machine, the motor 51. combination therewith of automatic stitch The program will operate similarly with the length adjustment means for adjusting the spa- second embodiment of the present invention ex- tial relationship of said knitting instrumentalities cept that motor 121 will be controlled rather than comprising motor 51. In some instances, it may be desirable to 45 means for detecting at least one of the control both motor 51 and motor 121 in knitting factors that affect the length of stitches being machine 20". formed by said knitting instrumentalities and In accordance with the present invention, vari- for generating a signal indicative of the factor ations in the knitting yarn feeding tension caused detected, by the inertia of the knitting section components, 50 elevating means for changing the spatial including the needle bed, and thermal expansion relationship between said knitting instrumental- thereof in high speed knitting can be corrected. ities, and Therefore, high quality fabric may be produced. control means connected to said detecting Moreover, by guiding a plurality of knitting yarns means for receiving the signal from said de- through a plurality of guides 85a, 85a" in the ten- 55 tecting means, comparing that signal to a pre- sion detecting member 81, 81", the or set value, and controlling said elevating means in the tension of the plurality of yarns, as to change the spatial relationship of said knit- opposed to that of individual yarns, can be de- ting instrumentalities and to adjust thereby the

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length of the stitches being formed responsive yarns and for generating a signal indicative of to the difference in the detecting means signal the tension in the yarns and for transmitting and the pre-set value whereby the length of that signal to said control means. the stitches is automatically adjusted to com- pensate for changes in the factors affecting 5 7. In a circular knitting machine including a rotat- stitch length. ing needle cylinder having vertical grooves in the periphery thereof, a plurality of cylinder 2. A knitting machine according to Claim 1 needles slidably mounted in the grooves in wherein said knitting instrumentalities include a said cylinder, a sinker cap mounted above and rotating needle cylinder having vertical grooves 10io outwardly of said needle cylinder, a plurality of in the periphery thereof, a plurality of needles sinkers mounted on said sinker cap and coop- slidably mounted in said grooves in said nee- erating with said cylinder needle to form knit dle cylinder, stitch cams for raising and lower- stitches to produce a single knit fabric, stitch ing said needles, and stitch cam holding cams for moving said cylinder needles verti- means for holding said stitch cams and being is15 cally in said grooves, cam holder means for mounted for vertical adjustment, and wherein holding said stitch cams in operative position said elevating means vertically adjusts said relative to said needle cylinder and said nee- cam holding means to adjust vertically said dles, mounting means supporting said cam cylinder needles to adjust the length of stitches holder means for vertical adjustment, and yarn being formed thereby. 20 feeding means for feeding a plurality of yarns to said cylinder needles, the combination 3. A knitting machine according to Claim 2 therewith of stitch length adjustment means wherein said knitting instrumentalities also in- comprising clude yarn feeding means for feeding at least means for detecting the tension in the plu- two yarns to said needles and wherein said 25 rality of yarns, determining an average tension detecting means detects the tension in the at in the yarns and generating a signal indicative least two yarns and signals the average ten- of the average tension in the yarns being fed sion per yarn to said control means. to said needles, control means for receiving the signal from 4. A knitting machine according to Claim 2 30 the detecting means and comprising a setting wherein said knitting instrumentalities further means for setting a desired average tension for include sinkers cooperating with said cylinder the yarns, comparison means for comparing needles and wherein the distance between the signal from said detecting means with the said needles and a stitch drawing top edge of value set by said setting means, and convert- said sinkers is adjusted by said elevating 35 ing means for converting the comparison result means. from said comparison means into a driving signal, and 5. A knitting machine according to Claim 2 adjusting means connected to said cam wherein said knitting instrumentalities further holder mounting means for vertically adjusting include a rotating dial positioned above said 40 said cam holder means responsive to said needle cylinder and having grooves in the up- driving signal. per surface thereof, and dial needles slidably mounted in the grooves in said dial and coop- 8. A knitting machine according to Claim 7 erating with said cylinder needles to form dou- wherein said control means further includes ble knit fabric, and wherein said elevating 45 second setting means for setting a predeter- means vertically adjusts said cam holder which mined range of permissible variation from the adjusts said stitch cams to adjust said cylinder desired tension set by said first setting means. needles relative to said dial needles. 9. A knitting machine according to Claim 7 6. A knitting machine according to Claim 3 50 wherein said control means also includes dis- wherein said tension detecting means includes play means for converting the signal from said a circular member mounted for rotation and detecting means into a feeding tension of the having at least two yarn guides therein through knitting yarns and displaying the same. which the at least two yarns pass, said circular member rotating in response to variations in 55 10. A knitting machine according to Claim 7 further the tension in the yarns, and means for sens- including yarn feeding means for positively ing changes in the position of said circular feeding the yarns to said needles, means for member upon variations in the tension in the detecting the yarn feeding speed and generat-

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ing a signal responsive thereto, comparison mounting said dial above the upper end of said means for comparing the yarn feeding speed cylinder and for vertical adjustment relative signal with a desired yarn feeding speed, step- thereto, the combination therewith of stitch less transmission means for changing the yarn length adjustment means comprising feeding speed settings according to the com- 5 means for detecting the tension in the plu- parison result of said comparison means, and rality of yarns being fed to said needles and means for transmitting the changed yarn feed- for determining an average tension therein and ing speed settings to said positive yarn feed generating a signal indicative thereof, means. control means for receiving the signal from io said detecting means and comprising setting 11. In a double knit circular knitting machine in- means for setting a desired tension for the cluding a rotating cylinder having vertical knitting yarns, comparison means for compar- grooves in the periphery thereof, a plurality of ing the signal from said detecting means with cylinder needles slidably mounted in the the desired value set by said setting means, grooves in said cylinder, a rotating dial having is and converting means for converting the com- radial grooves in the upper surface thereof, a parison result from said comparison means plurality of dial needles slidably mounted in the into a driving signal, and grooves in said dial, dial mounting means for adjusting means for adjusting the vertical mounting said dial above the upper end of said position of said dial relative to said cylinder cylinder and for vertical adjustment relative 20 responsive to the driving signal from said con- thereto, the combination therewith of stitch trol means. length adjustment means comprising means for detecting the distance between 15. A knitting machine according to Claim 14 the upper end of said cylinder and the periph- wherein said control means further includes ery of said dial and for generating a signal 25 second setting means for setting a predeter- indicative of the distance detected, mined range of permissible variation from the control means for receiving the signal from desired tension set by said first setting means. said detecting means and comprising setting means for setting a desired distance between 16. A knitting machine according to Claim 14 said cylinder and said dial, comparison means 30 wherein said control means also includes dis- for comparing the signal from said detecting play means for converting the signal from said means with the desired distance, and convert- detecting means into a feeding tension of the ing means for converting the comparison result knitting yarns and displays the same. from said comparison means into a driving signal, and 35 17. A knitting machine according to Claim 14 fur- adjusting means for vertically adjusting ther including yarn feeding means for posi- said dial relative to said cylinder responsive to tively feeding the yarns to said needles, means the driving signal from said control means. for detecting the yarn feeding speed and gen- erating a signal responsive thereto, comparison 12. A double knit circular knitting machine accord- 40 means for comparing the yarn feeding speed ing to Claim 11 wherein said detecting means signal with a desired yarn feeding speed, step- is a position sensor sensing the position of less transmission means for changing the yarn said dial mounting means. feeding speed settings according to the com- parison result of said comparison means, and 13. A knitting machine according to Claim 11 45 means for transmitting the changed yarn feed- wherein said control means includes second ing speed settings to said positive yarn feed setting means for setting a permissible range means. of variations in the distance between said cyl- inder and said dial. 18. A knitting machine according to Claim 14 50 wherein said tension detecting means includes 14. In a double knit circular knitting machine in- a circular member mounted for rotation and cluding a rotating cylinder having vertical having at least two yarn guides therein through grooves in the periphery thereof, a plurality of which the at least two yarns pass, said circular cylinder needles slidably mounted in the member rotating in response to variations in grooves in said cylinder, a rotating dial having 55 the tension in the yarns, and means for sens- radial grooves in the upper surface thereof, a ing changes in the position of said circular plurality of dial needles slidably mounted in the member upon variations in the tension in the grooves in said dial, dial mounting means for yarns and for generating a signal indicative of

8 15 EP 0 652 314 A1 16

the tension in the yarns and for transmitting relative to the needle cylinder to adjust the that signal to said control means. length of the stitches being formed to produce a double knit fabric having more uniform stitch- 19. A method of producing a knit fabric on a es therein. circular knitting machine having a rotating nee- 5 die cylinder, knitting needles slidably mounted on said cylinder for vertical movement relative to other stitch forming elements which coop- erate with the cylinder needles in forming knit stitches, and yarn feed means for feeding a 10 plurality of yarns to the needles, said method comprising the steps of detecting the tension in the plurality of yarns being fed to the needles and computing an average tension in those yarns, is comparing the average tension computed with a pre-set desired value of tension for those yarns, converting the results of the comparison of the pre-set value with the detected average 20 value into an adjustment value, and adjusting the vertical position of the cyl- inder needles relative to the other stitch for- ming elements to adjust the length of the stitches being formed to produce knit fabric 25 having more uniform stitches therein.

20. A method according to Claim 19 wherein the other stitch forming elements are sinkers hav- ing a stitch drawing top edge and wherein the 30 cylinder needles are adjusted relative to the stitch drawing top edge of the sinkers.

21. A method according to Claim 19 wherein the other stitch forming elements are dial needles 35 and wherein the cylinder needles are adjusted relative to the dial needles.

22. A method of producing a double knit fabric on a circular knitting machine having a rotating 40 needle cylinder, cylinder needles slidably mounted on said cylinder for vertical move- ment, a rotating dial mounted above the needle cylinder, dial needles slidably mounted on the dial for horizontal movement, and yarn feed 45 means for feeding a plurality of yarns to the cylinder and dial needles, said method com- prising the steps of detecting the distance between the upper end of the needle cylinder and the periphery of so the dial and generating a signal indicative thereof, comparing the signal generated from the detected distance with a pre-set desired dis- tance, 55 converting the results of the comparison into an adjustment value, and adjusting the vertical position of the dial

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17 Patent Number European EUROPEAN SEARCH REPORT Application Office EP 94 11 7387

DOCUMENTS CONSIDERED TO BE RELEVANT Citation of document with indication, where appropriate, Relevant CLASSIFICATION OF THE Category of relevant passages to claim APPLICATION qnt.CI.6) X GB-A-2 193 230 (ELITEX) 1,2 D04B9/06 * page 1, line 71 - line 121; figure 1 * X DE-A-20 12 085 (TRIP-LITE LTD) 1 * page 5, line 19 - page 7, line 22; figure 1 * A 2-4

A FR-A-1 490 120 (SCHIESSER GMBH) 1,5 * page 5, left column, line 22 - line 25; figure 1 *

D,A US-A-5 018 370 (TSUCHIYA)

A DE-B-12 89 611 (LAWSON-HEMPHILL INC.)

A GB-A-861 880 (THE HOSIERY AND ALLIED TRADES RESEARCH ASSOCIATION)

DE-A-26 31 858 (ELITEX) TECHNICAL Hf.lJJS SEARCHED (Int.CI.6) D04B

The present search report has been drawn up for all claims Place of search Date of conpletion of the search THE HAGUE 10 February 1995 Van Gelder, P CATEGORY OF CITED DOCUMENTS T : theory or principle underlying the invention E : earlier patent document, but published on, or X : particularly relevant if taken alone after the filing date Y : particularly relevant if combined with another D : document cited in the application document of the same category L : document cited for other reasons A : technological background O : non-written disclosure & : member of the same patent family, corresponding P : intermediate document document