ROTOTWIST BELMONT TEXTILE MACHINERY COMPANY

Transcription

1 ROTOTWIST BELMONT TEXTILE MACHINERY COMPANY PROCESS DESCRIPTION ROTOTWIST is a process to produce twisted, plied yarns of 2 to 6 plys in a continuous, highspeed operation. Individual ends are fed from a creel with good tension control to a pneumatic twist block that imparts S and Z twist alternately to the singles. Ends with singles twist, when combined and allowed to swivel, automatically ply together due to the latent torque. The ply twist resulting from this union will be opposite to the singles twist, ie. S-singles will result in Z- ply. It is obvious that unless the node of zero twist between S and Z plies is stabilized, or locked in some fashion, the yarn will, under stress, unply to strands with no twist. To prevent this, ROTOTWIST passes the yarn through a blast of air from a rotating controller to cause entanglement of filaments/yarns, thus locking the twist in place. The activation of the entanglement air must be timed to exactly coincide with the passage of the short zero twist segment of yarn. The air pressure used at the twist jet to impart singles twist, the tension on the yarn, and the process speed, controls twist level of the plied yarn. Twisted/entangled yarn is next taken up on an accumulator before passing to a wind up. The accumulator allows continuous operation of the twist unit, even when the winder is being doffed. Each side of the machine (A and B) may be run completely independently. This machine has two modes of operation Twist Mode, described above, and ET Mode. ET Mode is the same process as above except the Rotojet runs continuously and entangles the yarn in multiple places. This produces entangled yarn with short sections of twist, depending on the number of orfices in the Rotojet, or produces entangled yarn only. OPERATION Creel Twist/Rotojet Normal procedures are used to string-up and operate the creel in a package transfer mode. Weavers knots are preferred to prevent problems at the twist jets. Each end is passed through the IRO weft inserters and their tensioners. Ends may then be blown through the yarn transfer tubes to the twist unit. The active IRO units must be turned on and the S/Z switch placed in the Z position. Inactive IRO units must be off and the S/Z switch in the neutral position (the red indicator light should be on) Individual ends are passed through the transfer tubes and pulled through the appropriate twist cavity using a length of wire having a hook at one end. The wire is inserted into the top of the twist cavity (straight end first), through the Rotojet, and behind a snubbing bar. Yarn is caught in the wire hook and pulled through the assembly. This process is repeated for each of the singles ends.

2 Belt Nip Accumulator Wind-up All ends comprising the twisted yarn are gathered together and passed through the Belt Nip. On the Side A and Side B front control panel is switches to jog the Belt Nip. Use these controls to pass the yarn through the Belt Nip. Lead the yarn vertically up and through the correct opening in the top of the twist cabinet, through the guides on top of the cabinet, and over head to the Accumulator guides. Leaving a length of yarn on the floor, activate the accumulator using the control on the front of the twist cabinet to draw yarn into the accumulator, and around the mast. Use sufficient length to ensure that the yarn will be taken up when the unit is started. Finally, activate the missing end detector on top of the twist unit cabinet. Standard procedures are used to string-up the wind-up. PROCESS Process conditions are established on a series of touch screens located in the center of the twist cabinet. These are activated by touching the appropriate block to either enter or change data. Each screen will be discussed below. First Screen This screen is titled BELMONT TEXTILE MACHINERY COMPANY and is used to establish either English or Metric Units. MACHINE OVERVIEW This screen shows the yarn speed, accumulator speed (as a percent of yarn speed), and the twist reversal length. A button is provided to reset the drives for each half of the machine. Other buttons are to direct the operation to other screens, for example, Go to Twist Parameters, and View Alarms. In the center, at the bottom of the screen is a Change User button. This will bring up a numeric keypad allowing input of a code to open up a special screen Tech Control. The Tech Control screen is used only to change home position of the Rotojet, set yarn sensor delay time and to read run time. This screen will be discussed later. TWIST PARAMETERS Two identical screens are provided for either Side A or Side B. Conditions can be set differently for each side to run different processes on the individual sides. This discussion will not refer to a particular side but is generic to either. Six conditions buttons are provided on this screen to control different functions. The first is Twist Mode / ET Mode. This is a toggle button to change from one mode to the other. The Rotojet orfice must be homed after changing the Rotojet assembly. The second is Yarn

3 Speed. Touching this button brings up four new buttons on the right hand side, which allow the operator to either increase or decrease the line speed in increments of 10 or 100 yards/meters per minute and establishes the operating speed. Close these buttons when finished. The third button, Twist Reversal Length sets the distance between twist reversal/tack points. This is usually in the range of 48 to 96 inches (English) and is set by touching the button to bring up a 4-unit keypad, ±0.1 and ±1.0 inch. Close the pad when finished. The fourth button, Accumulator Speed establishes the under drive of the accumulator as a percent of the line speed. This speed should be set at 92% to begin, and adjusted during operation to give low tension (<50 gm) between the twist unit and the accumulator since it is in this zone where yarn plying takes place. Too high a tension will prevent plying and lead to excessive liveliness on the accumulator mast. On the other hand, if the tension is too low, yarn will wrap on the Belt Nip causing break out. Adjustment is made by, as before, bringing up the 4-unit control pad and making the desired change in increments of ±0.5 or ±1.0 percent. Close the keypad when finished. The button Tack Position Offset is used to adjust the time/distance offset between twist jet reversal and the tacking operation. This must be adjusted during operation to ensure that the reversal point and tack exactly coincide. As a guideline, the offset should be initially set according to line speed: 100 ypm 1 inch Examination of the yarn on the mast will dictate the amount and direction of offset to be used. Changes are made, as before, by touching the Tack Position Offset button the display the 4 unit key pad. If low twist is observed ahead of the tack the offset must be decreased, while if the low twist is following the tack, the offset must be increased. In some cases the actual point of twist reversal can be observed while in other cases the S and Z twist have neutralized and the reversal point is not seen. The final button adjusts accumulator ramp speed offset to maintain tension between the twist unit and the accumulator during startup and shut down. Adjustment is made similar to the other functions and once set should not require further attention. TECH CONTROL This screen provides several functions and is only reached after inputting a key code.

4 A) Home Position. The Rotojet must be homed to ensure proper position of the air orifice relative to the tack shoe and twist reversal node. Homing is accomplished by first removing the Extended Rototwist Cap exposing the "Tack Chamber Block" and the rotor. Any yarn should be moved out of the way. Then the following alignment is performed: 1.) Press Teach Home Position button to activate the function. 2.) Press Jog Low to display Jog High. 3.) Press Jog CW and hold while observing the tack chamber block (this may require a second person). 4.) When the orifice appears in the slot, release the jog button. 5.) Adjust the tack chamber block to center the orifice (right or left) in the slot. 6.) Press Jog High to display Jog Low. 7.) Using either Jog CW or Jog CCW, rotate the orifice to the upper end of the slot. The orifice should be centered and fully exposed but without any of the rotor showing between the tack chamber block and the orifice. 8.) When the correct position is achieved, press the Teach Home Position Button again to lock in this setting. B) Yarn Sensor Delay. This function controls the time delay of missing yarn sensors to prevent false shut downs due to momentary loss of signal due to vibration. The usual delay is 2-5 seconds, and once set should require no further adjustments. C) Total Run Time. Total run time of the equipment is displayed in this field and should not be reset except by Belmont Textile Machinery personnel. D) Twist Control and Overview return to the appropriate screens. ALARMS IRO Units This screen displays the alarm signals following an interruption or other fault. The information on this screen will help locate a problem and assist in the corrective action. Acknowledge and Clear buttons are provided. IRO units are threaded up according to procedures given in the IRO manual (attached). Units to be used must be turned on and the S/Z switch put in the Z position. The IRO unit also functions as a missing yarn detector and will stop the process when a fault is detected. Units not in use must be turned off and the S/Z switch put in the neutral position. If a yarn sensor signal causes the process to stop, the motor drives must be reset before the process will run again.

5 Twist Level Rotojet Twist level is adjusted primarily by the air pressure at the twist jet, although tension and speed have some impact on twist level. Normal working pressures are in the range of psi. (The higher the pressure, the higher the twist level.) Air pressure is adjusted in the back of the twist cabinet by two air valves, and adjustments should be made with the machine running to establish the correct pressure. Pressure drop is normal and the high pressure reading is taken as the set pressure. Air pressure is adjusted to give a good tack without causing filament breakage. The correct pressure depends on a number of factors such as number of plys, twist level, yarn denier, denier per filament, etc. Normal operating range is between psi and is set in the back of the cabinet. Tension Singles yarn tension is set by the brush and disc tensioner at the exit of the IRO units and is measured just above the twist jets. All ends should have the same tension within 2-4 grams. Exception might be if different denier yarns are used as the supply. Generally, the lowest yarn tension achievable is desired, thus a lower twisting air pressure may be used. Normal tensions range from grams for 650 denier yarns to grams for 2600 denier yarns. Tension entering the accumulator should be <50 grams, preferably about 20 grams. This is adjusted by changing the accumulator speed, or percent of line speed. Winding tension on the wind up should be adjusted as low as possible to prevent twist pull out on the package. Excessive tension will result in lower twist and snapping of the yarn as it is removed from the package. Tension < 50 grams is recommended. Start up When the yarn is strung up between the creel and accumulator, and all parameters have been set, the machine is ready to start. Be sure that the tension between the twister and accumulator is set by using the string up position on the panel. Press the start button, adjust accumulator tension as required, and check the twist level of the yarn on the mast. Make any adjustments required. Check that the twist reversal and tack are in the same place on the yarn, and if not make offset adjustments. At start up there will be a segment of no twist yarn to mark where start up occurred. This may be wound to waste or cut out and the ends tied together, which ever is preferred. Double ending This machine has been designed to run two ends of up to 6-ply or four ends of up to 3-ply of the same product on each mast. When running four ends per side the Twin Tack Shoe must be used. Care must be taken when

6 removing the yarn from the mast to the wind up to prevent twists and tangles. Sufficient length is required ahead of the wind up to allow separation of the individual tends. The equipment is designed to produce two yarns with different twist direction in the pair between each reversal, that is, while one yarn is Z twist the other will be S twist. This prevents spontaneous wrapping of the two ends. Shut down To stop the process simply press the stop button on the control cabinet. The wind up will have to be stopped independently.

7 DEFECTS AND POSSIBLE CAUSES DEFECT POSSIBLE CAUSE Low twist Insufficient air pressure at the twist jets Excessive yarn tension Restriction to yarn twist above the twist jets. Yarn over sized for the twist jet. High twist Excessive air pressure at the twist jets Low yarn tension Missed Tack Low air pressure at the tack jet Timing of twist jet not synchronized with the tack Air loss at the Rotojet (change internal seal). Improper alignment of the Rotojet tack chamber block Yarn denier is inappropriate for the tack chamber block Yarn on Accumulator Tension too low between twister and accumulator. Has Pig tails Yarn too tight on Tension too high between twister and accumulator. Accumulator Single yarn jumped Tension too low at the twist jet. To Adjacent Hole Low Twist Before Twist offset is incorrect. Adjust Or After Tack One Yarn Component Improper singles tension Either Cores or is Different deniers of supply yarns Loose. Loss of Twist Excessive reversal length Between Reversals Excessive singles tension Twist reversal and Tack point set improperly.