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  • 1. SEMINAR ON FLAT BED WEFT KNITTINGMACHINE
  • 2.  Introduction Single bed flat weft knitting machine -Needle -Cam carriage -Method of knit, tuck & float stitch formation Double bed flat weft knitting machine -Path of yarn -Cam carriage -Method of knit, tuck & float formation Computerised knitting machine
  • 3.  The first flat bar machine was demonstrated in 1862 and patented in 1865 by the Rev. Isaac Wixom Lamb. Flat machines are normally gauged on the English system number of needles per inch Generally flat m/c gauges range from 5 to12 npi But there are coarse gauge m/c of only 2.5 npi Some m/c are as fine as 14 to16 npi
  • 4. The needle consists of six main parts: Stem Hook Rivet Latch Butt Tail
  • 5. Raising cam /Stitch cam A pair of cams is provided on each side that gives direction to the needles both during clearing as well as during stitch formation, while one of the pair acts as a raising cam during one traverse, other will act as a stitch camSewing cam Situated below the raising/ stitch cam, it functions in guiding the needle butt from the clearing position on to the stitch cam for stitch formationUp throw cam Situated on each side of raising/stitch cams, it functions in bringing back the needles to their rest position
  • 6. Tuck lever and tuck lever Situated on each side of the sewing cam, the tuck lever functions in guiding the needle butt during the formation of tuck stitch for all needle butts kept at position ‘E’. A tuck lever lock is provided on top of each tuck lever so as to keep them locked at upward position for one or more carriage traverses during formation of tuck stitch.Tuck lever releaser Provided for each tuck lever, the tuck lever releasers are used to raise or lower the tuck lever to either lock or unlock position for the required no of traverses during the formation of a tuck stitch.Knitting dial Provided on the upper surface of the cam carriage ,the knitting dial may be rotated to adjust the tension in the yarn. The knitting dial tension results in change of slope of raising/ stitch cams.
  • 7. Position A:(Non knit position) At this position the movement of the carriage has no effect at all on the needles as the needle butt through the upper portion of the camPosition B:(knit float position) With the raising/stitch cam raised upwards, the needle butt at the position ‘B’ follow the ‘knit-path’ With the upper arm of the raising/stitch cam lowered, the needle butts at position‘B’Pass hindered through the cam without clearing or yarn feed so as to form a float stitch
  • 8. Position ‘C’& ‘D’: (knit, patterning, shaping) Needle butts at position ‘C’ will knit even when the upper arm of the raising/stitch cam is lowered the needle butt at position B form float stitch. Needle butts at position D may be used for special patterning & shapingPosition ‘E’ :(tuck stitch position) Needle butts at position ‘E’ will form the tuck stitch in conjunction with the tuck levers. For a single tuck, initially the tuck are raised to ‘lock’ position so that the needle knits at position’E’ pass unhindered.This causes the yarn to be fed below the latch which is open with the old loop already cleared at this position.On the return traverse, the tuck levers are lowered down to ‘unlock’ position. This then guides the needle butts at ‘E’ along the path as shown in fig. to bring them to position ‘B’.This causes the knocking over of path the old loop and the yarn fed at the previous traverse togther ,Thus forming a single tuck .similarly, a double tuck stitch may also be formed .
  • 9. Different parts of the machine are explained as below : Tensioner: Disc type tensioner is used. Yarn take up: Attached to spring at one end and functions in taking up any slackness in the yarn. Yarn feeder: Two yarn feeders are provided. These feed the yarn at correct position to the needle during each traverse in order that new loop may formed from it. Needle: Latch needle is used.
  • 10.  Needle bed: Two needle bed are used. Front and back needle beds are arranged so that their cross section form inverted v shape. Needle bed carry the needle in tricks that are present on each bed. Trick support the needle and guide it in motion during loop formation. Needle spring: Specially shaped metal wire fitted in each trick at bottom. Tip of each needle spring support the tail of each needle at its rest position. Latch brush: One for each bed, fitted to cam carriage being positioned above the needles. Function is to ensure that needle latches are fully open when needle reach the clearing position. Fabric comb and dead weight: A metal comb is fitted on the fabric formed between the two beds and dead weight are hung on the fabric comb and functions in applying the required to down tension ton to the fabric formed.
  • 11. 1.Rest position AL,AR -raising cam2.Tuck position BL,BR-cardigan cam3.Clearing CL,CR-stitch cam4.Yarn feed D-Guard cam5.Pre-knockover E-Slot for stitch length6.Knockover K-Needle path for knit7.Rest position T-Needle path for tuck F-Needle path for float
  • 12.  Two cam carriages , one for each bed are provided and traversed alternatively from left to right and right to left by the help of the operating handle . A row of needle loops are formed on each needle bed during each such traverse. The carriages are joined to each other by the help of a carriage bow and slide on guide rails that are fitted over each needle bed . Each cam carriage carries the cam system on its under surface while , the upper surface carries the controls for stitch length setting , unit loops , tuck stitch & float stitch. A symmetrical cam system provided on each carriage with each element of the cam occurring in pairs .
  • 13. Raising cam and cardigan cam It function in to raising the needle to its clearing height at each traverse.Two raising cams and two cardigan cams are provided on either side that alternatively perform the function at each traverse During a traverse from left to right , the needles enter the track from the right and accordingly the right hand set of each pair then actively functions while the left hand side set then merely act as guard cam. The roles are reversed in the opposite traverse. Both the cams are spring loaded so that they may be degressed in to the surface of the cam plate as per the nature of the stitch desired. They can accordingly be set by levers provided on the carriage upper surface into the following positions: Fully out: act on all needle butts. Partly withdrawn: act on the long butt needles but miss the short butt needles which thus pass the undisturbed across their face and over the slopings provided. Fully withdrawn: miss all the needles butts which pass undisturbed across their face and over the slopings provided
  • 14. Stitch camso Two stitch cams are provided on either side that alternatively performs the function of lowering the needles to the knock –over position at each traverse, while the left stitch cam actively functions during left to right traverse, the right stitch cam act as a guard .o On the opposite traverse the roles are reversed. Studs from each stitch cam are located in slots provided on the cam plate so that they may be raised or lowered along the slot for the purpose of altering the stitch length.Tuck track: The track lying above the raising cam that the needle butts follow if the Cardigan cams withdrawn to obtain the tuck stitch.Guard cam: Located above the cardigan cams the guard cams perform its usual functions of forming a closed track for the needle butts.
  • 15.  Knitting loops in one or both traverses on all needles of a bed: By keeping one or both slots of raising cams and cardigan cams in the fully out position. Float stitch in one or both traverses on all needles of a bed: By keeping one or both sets of raising cams in fully withdrawn position . Combination of knitted loops and floats in selected needles of a bed: By keeping one or both sets of raising cam in partly withdrawn condition and arranging the long and short butt needles on the bed as per pattern requirement.
  • 16.  Tuck stitch in one or both traverse on all the needles of a bed: By keeping one or both sets of cardigan cams in fully withdrawn condition while the raising cams are fully out. The needles are then not raised to the clearing height but pass across the face of the cardigan cams unhindered along the tuck track.The path of the needles through the cam is as shown. Combination of tuck stitch and knitted loops in selected needles of a bed: By keeping one or both sets of cardigan cams in partly withdrawn condition while the raising cams are fully out. The short and long butt needles are accordingly arranged on the bed as per pattern required. Combination of tuck and float stitches in selected needles of a bed: By keeping one or both sets of cardigan cams in fully withdrawn condition while the raising cams is partly withdrawn. The short and long butt needles are accordingly arranged as per pattern requirement
  • 17. Fabric produced in Double Flat Bed Single jersey plain knit Double jersey knit 1x1 Skeleton rib 2x2 Swiss rib 2x2 English rib Half cardigan (single tuck) Full cardigan (single tuck) Double half cardigan (double tuck) Double cardigan (Double tuck) Float stitch
  • 18.  Computer Controlled Single System Flat Bed Knitting Machine
  • 19. There are two parts of the computerized flat knitting machines: computer controller & computer pattern preparation system The computer pattern preparation system is used to design the knitting data for the computerized flat knitting systems All knitting data needed for machine operation are programmed in the keyboard and simultaneously displayed on the monitoring screen. These data are composed of function control data and needle After the knitting data are finished, they are saved in a 3.5 inch micro-floppy disk and fed into controller
  • 20. Control system has following functions :(1) All knitting data from the pattern preparation systems can be fed into the controller by insertion of the floppy disk into the driver in the controller panel, or can be transferred to the controller by a communication network; (2) The knitting data currently used for each course can be displayed on the monitoring screen;(3) The knitting data can be modified and the modified data can simply be fed back to the floppy disk if needed;(4) Diagnostic operations of electrical parts can easily be done by maintenance mode in the software system;(5) The control data of cam operations, knitting speeds, fabric take-down speeds, racking positions, stitch positions and density, yarn assembly and needle selection should be included in all knitting data;(6) Various sensors and micro-switches should be checked and handled to complete various functions.
  • 21. Output executors include a carriage motor, a fabric take-down motor, a rack motor, eight stitch motors, cam solenoids, yarn solenoids, selector solenoids, presser solenoids and so on.Input signals include various sensors and micro-switches, such as the course synchronous signal, the needle, synchronous signal, the start/stop signal and trouble signals
  • 22.  Dimensions E5-14 Length: 4720 mm including monitor Width: 960 mm Height: 1680 mm Weight:-net kg (approx.) 1250 Technical Specifications Gauges E 5, 7, 8, 10, 12, 14 (additional gauges on request) Systems 2 identical systems (2 x 1 or 1 x 2) Any cam system can simultaneously and selectively transfer or receive stitches. Five way technique: individual selection of long and short stitch, long and short tuck loop, and floating. Each system can be used for knitting or transferring not depending on the carriage traverse direction. Transferring can be carried out from the front to the rear, from the rear to the front, or in both directions simultaneously. Working Width 1 x 2 systems: 90 inches = 2286 mm 2 x 1 systems: 2 x 43 inches (max.) = 2 x 1092 mm
  • 23.  Main Drive Reversible drive with AC servo motor and flat toothed belt. Programmable speed up to 1,2 m/s Carriage One light alloy carriages of compact construction. Needles Retracted UNIVERSAL spring latch needle with spreading spring for transferring. Needle Selection Electronic individual needle selection via mono magnets. Stitch Length Two different values controlled by separate step motors, can be programmed not depending on each other as static,dynamic, or selective stitch length, or as combination of those. Fabric Take-Down Convenient electronically controlled fabric take-down unit. The take-down tension can be programmed or is calculated automatically depending on the number of needles used. Fast run and reverse run (for releasing the fabric) can be controlled as required. Continuous fabric take-up roller. Yarn Carrier Rails 4 double profile rails with 8 yarn carrier boxes. The yarn carrier boxes can be used as single or multiple boxes
  • 24.  Yarn Guide Unit Low bobbin board, height of the yarn guide unit can be adjusted. 11 (16 for gauge E5) combined knot and yarn break detectors with indicator lamps. Yarn-retrieval unit. Safety Units Closed transparent cover with electrical and switch according to DIN EN 1088. Emergency shut-down according to EN 418 Signaling Device Yellow colour highly-visible signal lamp indicating error stop. Fault Detectors Yarn breakage, knot, load-up, shock, overload, fabric loss, fabric wind-up, and temperature control of important control units. Control Modular multi-processor system with CAN field- bus system and standard PC as host computer. Pattern Memory Dynamic memory management, large knitting programs can be processed.Multiple patterns can be loaded into the memory box.
  • 25.  Operating console Standard 15" multi-sync colour monitor. PC compatible keyboard with trackball (operating element). Recording medium 3.5" HD diskette. Programming All the fabric can be programmed on the machine directly using convenient and clear lists. Data storage On hard disk. Electrical Connection Power consumption max. 2.5 kwatt. Voltage adjustable for 190V, 200V, 230V, 280V, 346V, 380 V, 400V,415V, 440V. Mains frequency 50/60 Hz.
  • 26. Special Equipment Powerfail (correct continuation of the knitting program after cutting-out of the circuit) Stitch splitting on each cam system (front and rear), can be activated by the knitting program. Three-colour highly-visible signal lamp indicating production, operational stop, and error stop Carriage removal device Additional bobbin plates Bobbin supports (magnets) Individually spring-suspended take-up rollers Positive feeding device Lubricating unit Blowing unit Fabric spreader
  • 27.  Highly efficient Versatile knitting machine, not only for cut-and-sew knitwear but also for integrally-shaped panels and whole garments. The mechanically-controlled power flat machine is time-consuming And costly during machine changes and its more limited facilities provide less scope for adjustment.