Friday, March 5, 2021
Weft pattern chain preparation for Crompton and knowel's drop box motion:
The selection of shuttle boxes is performed by either separate pattern chain and cylinder or by dobby and Jacquard.
The separate selection mechanism is used in the loom having tappet shedding. The pattern capacity of separate selection mechanism is limited. A chain of plates and cylinder are used in separate selection mechanism. On pattern chain plate is used for two picks. The shuttle box position from 1 to 4 is avoided.
The box selection is performed in dobby and Jacquard loom by using separate jack levers or hook. The figuring capacity of dobby or Jacquard get reduce in this situation. The no. Of picks in weft pattern gets increased in this situation.
Meaning of different chain's plates for Crompton and knowel's drop box motion:
You can understand the meaning of each plate to be using for different shuttle box as shown in below picture:
Weft pattern chain preparation for given weft pattern for Crompton and knowel's drop box motion:
Thursday, March 4, 2021
Knowele's drop box motion:
Structure of Knowle's drop box motion:
This mechanism receives motion from the bottom shaft. Two driving gears fastened on the bottom shaft. These driving gears have half teeth on their periphery. The direction of the teeth of driving gears just opposite to each other. There are two eccentric shafts used in this drop box motion. Each eccentric shaft gets mounted at both sides of the bottom shaft. The eccentrics are mounted on their respective eccentric shafts as shown in the figure. A sliding dog tooth gear is mounted on each eccentric shaft opposite the driving gear. The engaging and disengaging of sliding dog tooth gears are controlled by sliding dog tooths. The sliding dog tooth gets operated by a selection mechanism through an independent pattern chain and cylinder or dobby. The eccentrics are connected with a box unit lever through intermediate levers. A spring-loaded stud is used to prevent the damage of the shuttle or shuttle box in case of incorrect settings or mishappening.
Working principle of knowele's drop box motion:
The driving gear is mounted on the bottom shaft. Since it is fastened on the bottom shaft so that it rotates with the bottom shaft. The sliding dog tooth gear is mounted on the eccentric shaft in such a way that the teeth of the sliding dog tooth gears do not touch the teeth of the driving gears in normal condition. The sliding dog tooth is attached with sliding dog tooth gear. As the sliding dog tooth receives the motion from the selection mechanism, it pushes the sliding dog tooth gear toward the driving gear. The continuously rotating drive gear gets engaged with the teeth of the sliding dog tooth gear. This sliding dog tooth gear rotates for half revolution because the driving gear has half teeth on its periphery. Now the sliding dog tooth gear's teeth get disengaged again. The position of sliding dog tooth gear gets unchanged till the weft pattern does not demand the change in the box position. Since the sliding dog tooth gear is mounted on the eccentric shaft so that the eccentric also rotates for the half-round. This motion is transferred to the box unit lever through an intermediate lever. Thus the position of the shuttle box gets changed.
The spring-loaded stud remains engaged with a cut out on the box unit support shaft to drive the boxes up and down. If the shuttle is projecting from the box so that full movement of the box unit is not possible. In this situation, the catch will be forced out of the cut-out that the drive mechanism will make it a full movement but box unit movement will be limited and damage avoided.
The initial position of the rear eccentric with connection is the up position and the initial position of the front eccentric is a down position.
When the rear eccentric is in the up position and the front eccentric is in the down position, then the first ( top box) box gets leveled with the race board.
If rear and front both the eccentrics go in their up positions, then the second shuttle box gets leveled with the race board.
If rear and front both eccentric come in the down position, the third shuttle box gets leveled with race board.
If the rear eccentric is in the down position and the front eccentric is in the up position then the fourth box gets leveled with the race board.
Wednesday, March 3, 2021
The fancy yarn is a yarn that looks different from regular yarns. The yarn surface of fancy yarns is modified by different methods. The common examples of fancy yarns are given below:
Tape or ribbon yarn may be produced using various processes including braiding, crocheting, warp knitting, and weft knitting. In recent times this material has become better known especially in fashion knitwear. It is also possible to use narrow woven ribbon, narrow tapes of nonwoven material, or slit film in the same way. The taps yarns are manufactured in a tube and flat form.
This is the simplest fancy yarn. In this fancy yarn, two yarns of different colours are twisted together in the yarn doubling process. The texture of marl yarn looks different from normal double yarn. These yarns are used to manufacture discreet pinstripes in man's suitings. Irregular patterns are also made in the knitted fabric.
The knop yarn contains prominent bunches of one or more of its components. These bunches get arranged at regular or irregular distance intervals along yarn length. It is usually produced by using an apparatus with two pairs of rollers. Each pair of rollers has the capability to operate independently. This arrangement makes it possible to deliver the base thread intermittently. The knoping thread gets delivered continuously. The twist insertion collects the knoping thread into a knop or bunch. The vertical movement of the knoping thread forms a knop. The vertical movement of knoping bars determines whether knop is small and compact or spread out along the yarn length.
A diamond yarn is produced by folding a coarse single yarn or roving with a fine yarn or filament of contrasting colour using S-twist. This is cabled with similar fine yarn using Z-twist. Multifold cabled yarn may be made by extending and varying this technique to produce a wide range of effects.
A gimp yarn is a compound yarn consisting of a twisted core with an effect yarn wrapped around it so as to produce wavy projection on the yarn surface. Since a binder yarn requires providing stability to the structure so that complete yarn gets produced in two stages. First of all, two yarns of widely varying counts are plied together. Thick around thin and are then reverse bound. the process of reverse winding removes the twist that creates a wavy profile as it makes the effect yarn longer than the actual length of the complete yarn. The texture properties of gimp yarn are clearly better than spiral yarn.
Spiral or corkscrew yarn:
This is a plied yarn displaying the characteristic smooth spiraling of one yarn component around the other. It is very similar to the marl yarn. One yarn is overfed in spiral yarn.
This type of yarn is characterized by a tight loop projecting from the body of the yarn at fairly regular intervals. These yarns consist of three different yarns. The three components of yarn are core, the effect, and tie or binder. The effect yarn is wrapped in loops around a core or base yarn. The third ply ( binder) is wrapped over the effect ply in order to hold the loops in place.
The loop yarn consists of a core yarn with an effect yarn wrapped around it and overfed to produce a nearly circular loopy projection on its surface. The core yarn has two plies twisted together. Core yarn entraps the effect yarn. Generally, four yarn are used to produce this yarn. Two yarns make core or ground yarn. The effect yarns are formed with an overfeed of 200 % or more. The effect yarn is not entrapped completely by ground threads, therefore, is necessary. The size of the loop is determined by the level of overfeeding.
This is a staple fiber yarn. It consists of a core of parallel fibers. These fibers are bound together by wrapper fibers. Yarn produced by the air-jet spinning process is structured in this way. The yarn produced by the hollow spindle method is also frequently as fascinated yarn, as a binder is applied to an essentially twistless core of parallel fibers.
In this kind of yarn, the slubs are deliberately created to make desired discontinuity effect in the yarn. The slubs are thick places in the yarn that may take the form of a very gradual change with only a slight thickening of yarn at its thickest point. The thickness of the slub gets three to four-time coarser than base yarn. The yarn thickness is achieved for short yarn lengths.
The actual chenille yarn is produced from a woven leno structure that is slit into a narrow, warp-wise stripe to serve as a yarn. the chenille yan contains piles on its surface. The pile length gets almost uniform throughout the yarn length. The pile length may also be varied if you produce irregular pile length. These yarns are used in furnishing and apparel. It has fuzzy and soft piles. the specialized machine is used to produced chenille yarn.
The covered yarn has a core that is completely covered by fiber or another yarn. The core yarn may be elastomeric yarn such as rubber, spandex, or any other yarn. It is manufacture by single or double covering both. The second covering is usually twisted in the opposite direction of the inner covering. The fabric made with these yarn has a heavier weight.
The metallic yarn may be made of monofilament or ply yarn. There are two kinds of processes used to manufacture metallic yarn. The lamination process seals a layer of aluminium between two layers of acetate or polyester film which is cut into strips for yarn. The metalizing process vaporizes the aluminium at high pressure and it gets deposited on the polyester film.
Monday, March 1, 2021
Reasons for end breakages in ring frame process:
Ring frame is a final process where the desired count of yarn is produced. The end breakage rate in the ring frame process greatly influences the productivity of the machine. The ring frame uses roving as feeding material. The reasons for end breakages in the ring frame depend upon the quality of roving, machine setting, machine maintenance. count to be spun, process parameters, and climatic conditions of the spinning room. The main reasons for end breakages in the ring frame process are given below.
End breakages due to roving faults:
- Undrafted material in the roving due to higher twist multiplier.
- Undrafted material in the roving due to low break draft.
- Improper piecing of sliver during cane changing in the roving process.
- Uneven roving.
Ends breakages due to machine setting and maintenance in ring frame:
The machine setting and maintenance play a very important role in the end breakage rate in the ring frame process. If a spinner selects proper machine settings and he keeps his machine in well-maintained condition, the end breakage rate is minimized up to optimum level. The main possible reasons behind end breakage due to machine setting and maintenance are given below
- Roller cots buffing interval time
- vibrating or out centered spindle
- vibrating or defective ring bobbin
- traveler replacement interval time
- floating fluff
- traveler flying off
- failure of suction clearer
- fluff accumulation inside the traveler
- torn apron
- faulty cradle.
- worn out bearings and gears
- worn-out ring
- improper top roller setting
- improper top arm pressure
- traveler fly due to high clearance between ring and traveler profile
- jerk during the traverse of the ring rail
- lappet height setting
- burnt traveler
- traveler clearer setting
End breakage due to improper process parameters:
The all the process parameters in the ring frame are selected according to the yarn count produced and the material to be processed. Improper parameter selection in the ring frame process always results in the form of quality and productivity of yarn. Some of the process parameters influencing the end breakages in the ring frame process are given below:
- Incorrect traveler according to count to be spun.
- Incorrect spacer size.
- Lower top arm load than required
- Shore hardness of cots of top roller and cots diameter
- Balloon collision due to inappropriate winding tebsion
- Bigger bobbin size
- Higher traveler
- Higher cope diameter
- Higher chasing length
- Inappropriate yarn tension according to yarn strength
- Lower twist multiplier
End breakages due to climatic conditions of the spinning room:
The performance of the ring frame gets directly influenced due to the climatic conditions of any spinning room. The main reasons affecting the end breakage in the ring frame process are given below:
- The relative humidity of the spinning room ranges between 46% to 55 %. The working temperature ranges between 70 degrees F to 78 degrees F.
- Higher temperature causes end breakages.
- Higher relative humidity causes moisture deposition on the drafting roller.
- Lower relative humidity causes drafting problems between rollers.
Friday, February 26, 2021
- This is a special type of weave. This is also known as warp pile fabric.
- The loops of yarn appear on either a single side or both sides of the fabric.
- There are two series of warp used to construct this kind of fabric.
- One series is called the ground warp and the other series is known as pile warp.
- The loop formation on the fabric surface takes place by this pile warp series.
- One series of weft yarn is used to weave terry weave.
- The terry weave or terry fabric can not be woven on normal looms( the loom which weaves flat fabrics).
- This weave is woven on the loom having a special mechanical arrangement.
- There are two independent let-off motion mechanisms mounted on terry looms.
- The let-off motion gets positively driven.
- Two different warp beams are used in the terry loom.
- Terry loom is equipped with either with dobby or jacquard shedding mechanism.
- A special type of reed is used in this loom. the structure of dents of the reed is designed in such a way that the pile and ground end lie separated in a dent. two rows of dent wire are used in this kind of reed.
- The loom is equipped with variable reed sweep motion or variable fail of the cloth motion.
- Since the terry cloth is a heavy fabric so that a suitable take-up roller is used in this kind of machine.
- The fabric is wound on cloth roll through batching motion in some weaving mills. this batching motion - reduces the doffing time. the piece length is also increased.
Types of terry fabrics:
The terry fabric is classified on different bases. The different bases of terry fabric classifications are given below:
1 - According to weave:
Three pick terry:
Four pick terry
Five pick terry
Six pick terry
According to loop geometry
According to loop disposition
Single side terry
Double side terry
According to surface modification:
According to use:
Terry weave construction:
Thursday, February 25, 2021
Side fork motion or weft fork motion ( an auxiliary loom motion)
The side fork motion is an auxiliary loom motion. The main objective of side fork motion is to stop the machine immediately in case of weft insertion failure during weaving. The side fork motion is mounted at the starting handle side of the loom. Since this mechanism gets mounted at the one side of the loom so that this mechanism is called side fork motion. This side fork motion helps to improve both quality and productivity.
Structure of side fork motion:
A grid is mounted between one end of the reed and the mouth of the shuttle box. The race board has a grove just opposite the prongs of the fork. the prongs of the fork get operated in this grove of the race board. This grid gets parallel to sley and in front of the prongs of fork F. The fork F is fulcrummed at fulcrum point G. The fork is mounted on the weft fork lever K. The fork has prongs at one end and a tail hook H at another end. This fork is made of lightweight material. The weight of the tail hook side is greater than the side of the prongs. Normally, the tail hook H of the fork F rests on the hammer lever notch J just because of the higher weight of the tail hook H. The knock-off lever L is mounted just behind the weft fork lever K. The other end of the knock-off lever gets touched to starting handle M. A cam B is mounted on the bottom shaft A of the loom. The greyhound tail lever D and the hammer lever I are connected to each other and they are fulcrummed at the joint of both levers. A bowl C is mounted at the end of the greyhound tail lever D. Bowl C touches the cam B.
When the bottom shaft rotates, the cam B mounted on the bottom shaft also rotates with the bottom shaft. The cam imparts up and down movement to the bowl mounted at the end of the greyhound tail lever. Since the greyhound tail lever and hammer lever are connected to each other and get fulcrummed at the joint of both levers so that the cam imparts to and fro motion to the hammer lever.
The side weft fork motion performs its work when the sley moves to the front dead center position. The prongs of the fork push the weft yarn present in the shed in a normal running position of the loom. When prongs of fork strike the weft yarn, the tail hook of the fork lifts up and the loom gets to continue to running position. The cam makes one round when the crank shaft makes two rounds.
If the weft yarn gets absent due to any reason during loom working, the tail hook of the fork falls down on the hammer lever. Since the hammer lever makes to and fro motion, the hammer lever notch carries the weft fork lever with it. The weft fork lever pushes the knock-off lever in this situation. The knock-off lever strikes the starting handle and the starting handle gets disengaged. In this way, the loom is stopped in a weft break situation.
Monday, February 22, 2021
Eccle'smultiple box motion:
The main objective of multiple box motion is to change colour of weft yarn as per fabric weft pattern. It is mounted at each side of the loom. If a fabric having more than one colour or count in the weft yarn, the multiple box motion gets compulsory in the loom.
The eccle's dropbox motion is positive multiple box motion. A pattern cylinder is used to select the shuttle box. 4 shuttle boxes are used in this type of dropbox motion at one side of the machine.
Structure of eccle's dropbox motion:
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