Fabric Club Of BD: 11/01/2010

BASIC INFORMATION OF TRICOT WARP KNIT FABRIC

Labels: Knitting Manufacturing Technology | at 11/21/2010 04:39:00 PM

Introduction

A warp knit fabric in which the fabric is formed by interloping adjacent parallel yarns. The warp beam holds thousands of yards of yarns in a parallel arrangement, and these yarns are fed into the knitting area simultaneously. Sufficient yarns to produce the final fabric width and length are on the beam. Tricot knits are frequently used in woman's lingerie items such as slips, bras, panties, and nightgowns.

Tricot is a special case of warp knitting, in which the yarn zigzags vertically, following a single column ("wale") of knitting, rather than a single row ("course"), as is customary. Tricot and its relatives are very resistant to runs, and are commonly used in lingerie."

Tricot knitting is usually done with machines, and is used for track clothing, and bike shorts. This form of knitting is found in vintage knitting patterns, but is not much in favor for hand knitting.

The versatile tricot knit fabric in a variety of types in 18, 24, 32 and 36 gauges and 2 and 3 bar material. The primary advantages over woven or circular knit products include wide working widths, cost effectiveness and difficulty to unravel or run. The forms and functions of tricots are so varied that one can scarcely tell the two different constructions were actually made on the same machine.

Tricot meshes are used in safety wear or bags. Tricot tulles are used in composite structures and crinoline dresses. Tricot satins are used in intimate apparel, costumes or cap and gown. Tricot jersey is used in linings or lingerie. Brushed tricots are used for pocketing or lining. Lightweight mono filament tricots are used in interlinings or fusible. Tricots are used in athletic wear mesh jerseys or dazzle shorts. The following types of tricot knit fabric:

Jersey
Stabilized
Marquisette
Satin
Meshes
Net
Novelty
Eyelets
Brushed
Military Spec
Mono filament (15 denier, 20 denier, 30 denier)

Tricot Knit Fabric Capabilities

Jersey Knit

Width stretch, drape and hand characterized the jersey tricot. It’s thin but very strong. Depending on the luster of the yarn, it may appear very bright or dull (matte). Nylon jerseys are used in intimate apparel: panties, bras, slips, lingerie. They are also good in linings, backings and substrates.

Stabilized Tricot Fabric

Stabilized tricots are engineered to minimize the width and length stretch inherent in knit products. This category substitutes for woven products wherever a low cost solution is needed. In automated sewing, where stretch can change the spacing of sewn-in components, stabilized tricots fill the need. When cut into bands as in binding, they have just enough stretch to encompass the raw edge of finished fabrics and it will not unravel. Stabilized tricots will work where fabric needs to lay flat, where fabric should not neck-in and where fabric that does stretch needs a limiting co-laminate.

Marquisette Knit Fabric

The marquisette pattern is somewhat like a square-holed window pane pattern. While it may appear to be an interlacing of yarn ends, it is actually a knitted structure which unlike its woven counterparts, will not unravel without great effort. Depending on the construction, marquisettes may be very open or very dense.

Satin Tricot Knit Fabric

Like its woven counterpart, satin tricots have an exceptionally smooth surface and if bright yarns are used, have a brilliantly lustrous shine. Unlike its woven counterparts, it will not unravel and it is available in widths up to 120”

Mesh Knit

Pattern atlas tricots are a category which includes all the eyelet patterns you might see in athletic-wear or intimate apparel. There are also meshes for flags and banners which do not unravel and are resistant to wind tear.

Net Knit Fabric

The net category of tricot comprise a very wide array of ‘mostly hole’ fabrics of sizes and shapes varying from very tiny to quite large; round to square to hex. Almost any kind of net can be made on a tricot and can be made wide up to 220”

Novelty Fabric

Novelty patterns can be integrated into a tricot base such as florals, dots, stripes, fleur-de-lis, etc.

Eyelet Knit

Eyelets are a novelty pattern which include double or single hole eyelets. The fabric is mostly fabric but has what appear to be perforations throughout.

Brushed Tricot

Brushed tricot is a tricot where the surface has been mechanically brushed and individual filaments have been randomly raised to impart a sift hand

Military Spec

If you are a military contractor, tricots may be a part of your supply chain. We are experienced in meeting the rigorous standards of the military. We have testing and certification available to the military contractor.

Monofilament

Monofilament fabrics are produced from the finest yarns on earth. These fabrics are soft, thin, and sheer and can be constructed to perform well in many end uses.

Industries Served

Apparel
Intimate Apparel: bras, panties, lingerie
Filtration
Medical Products
Industrial Products
Safety Products
Lamination
Binding
Military
Aerospace
Composite Structures
Gloves
Molding
Tape
Automotive
Geotextile
Construction
Acoustical
Sign, Flag and Banner

Knit Fabric Information

Tricot Material	18, 24, 32 and 36 gauge 2 and 3 bar
Fibers Used	Nylon Polyester Cotton Rayon PLA Carbon
Specialty Yarns Used	Solution Dyed Colors Fluorescent Anti Microbial Flame Retardant Recycled
Yarn Sizes	15/1 Nylon 20/1 Poly 20/12 Poly 40 Poly 50 Poly 70 Poly 150 Poly
Post-Finishing Processes	Embossing Printing Molding Brushing Slitting
Fabric Standards	Nafta Certified Fabrics Cafta Certified Fabrics Made in U.S.A. Fabrics Military Spec CFR 1610 NFPA 701 REACH CPSIA Cal. Prop 65

WARP KNITTING

Labels: Knitting Manufacturing Technology | at 11/19/2010 06:07:00 PM

Warp knitting:

Warp knitting represents the fastest method of producing fabric from yarn. Warp knitting differs from weft knitting in that each needle loops its own thread. The needles produce parallel rows of loops simultaneously that are interlocked in a zigzag pattern. Fabric is produced in sheet or flat form using one or more sets of warp yarn. The yarns are fed from warp beams to a row of needles extending across the width of the machine. (Figure)

Types of warp knitting:

1) Tricot Knit: Tricot fabric is soft, wrinkle resistant & has good drapability. Tricot knits are used for a wide verity of fabric weights & design. It makes light fabric weighting less than 4 ounce/square yard. Some examples of tricot fabric are sleepwear, boluses, dresses etc.

2) Raschel Knit: The Raschel knit ranks in importance of production with tricot but it makes varieties of products ranging from laces, power nets for foundation garments, swimwear to carpets. Raschel knitting is done with heavy yarns & usually has a complex lace-like pattern.

3) Crochet Knit: This basic stitch is used in hand crochet. This construction is used in a wide variety of fabrics ranging from nets & laces to bed spreads & carpets, various types of edgings or trimmings lace are also produced.

4) Milanese Knit: The milanese stitch produces a fabric very similar to tricot. It can be identified by the fine rib on the face & a diagonal pattern on the back. However, milanese fabric is superior to tricot in smoothness, elasticity, regularity of structure & friction resistance.

Uses of warp knitted fabric:

1. Inner wears (brassieres, panties, camisoles, girdles, sleepwear, hook & eye tape.)

2. Apparel (sportswear lining, track suits, leisure wear and safety reflective vests.)

3. Household (mattress stitch-in fabrics, furnishing, laundry bags, mosquito nets & aquarium fish nets.)

4. Shoes (inner lining and inner sole lining in sports shoes and

industrial safety shoes.)

5. Automotive (car cushion, head rest lining, sun shades and lining for

motorbike helmets.)

6. Industrial (pvc/pu backing, production masks, caps and gloves (for

the electronic industry.)

PICKING MACHANISM ON PROJECTILE WEAVING MACHINE

Labels: Weaving Manufacturing Technology | at 11/13/2010 01:17:00 AM

Main parts:

1. Torsion bar A: As shown in fig it has splinted ends as seen in the fig one end is secured firmly at the clamping flange with provision for adjusting twisting angle. The twisting length of the torsion is 721 mm. It is diameter is 15, 17 or 19 mm depending upon the model. Larger the diameter higher the initial projectile speed. The angular twisting of torsion bar at commencement of picking is 28-30^O.

2. Picking shaft B: The free end of the torsion bar is linked with the picking shaft through spines.

3. Picking lever C: The picking lever is clamped on the picking shaft.

4. Picking shoe D: The picking lever carries the picking shoe at its top end.

5. Picking shaft lever E: It is a rigid part of the picking shaft.

6. Toggle plates F: The toggle plates center at o carry a roller G and connected to the picking shaft lever E through a link H .They are covered at the bottom.

7. Picking cam I: It is mounted on a shaft J and rotated by bevel wheels K once every pick. It rotates in the direction of the arrow shown in fig. It carries a roller R after the nose part.

8. Oil break L: The shock of the picking is taken by the oil break.

A=Torsion bar , B=Picking shaft ,C=Picking lever , D=Picking shoe ,E=Picking shaft lever ,F=Toggle plate , G=Antifriction bowl , H=Link , I=Picking cam , J=Shaft ,K=Bevel wheels, L=Oil brake , P=Projectile ,R=Projectile guide.

Fig: Picking mechanism on projectile weaving machine.

Working Principle:

Weft is withdrawn from the package through a tension device, weft tensionar, shuttle feeder, scissor, and weft end gripper. The picking arm has released the projectile which is shown in the guide teeth at the mid-shed position. At the receiving side the weft end gripper is positioned to grip the weft after reception. The shuttle break is shown in its operating position with the shuttle returner ready to push the projectile to the release and tucking position.

Illustrates the torsion bar picking system of the machine. Strain energy is developed in the bar and released in such a way as to transfer the maximum possible strain energy to the projectile before it separates from the picker shoe. The torsion bar (A) has its splined ends rigidly constrained in an adjustable housing with provision for adjusting the maximum angle of twist and projectile initial velocity. The other end of the torsion rod is splined into the picking lever (C) which carries the picking shoe (D) at its extremity. The projectile (P) is illustrated in the shuttle lifter with the projectile spring opener. The bevel wheel (K) rotates the picking cam shaft (J) which carries the picking cam (I). The picking shaft lever (E) is rigidly connected to the torsion bar and through a short linkage to the toggle plate (F) center at anti friction bowl (G).The action of the cam is for the small roller to bear against the toggle rotate it anti clockwise about anti friction bowl (G), thus withdrawing the picking shoe to its rearmost position. In this position the center of the toggle arrangement are in line and the torsion bar is twisted to its predetermined angle. The nose of the picking cam then bears against the roller carried between the toggle plates and moves the central pivot of the toggle system off line center, thus permitting the strain energy in the rod to be transmitted instantaneously to the projectile. The projectile separates from the shoe after 6.4 cm travel in 0.007 s as a velocity of about24.4 m/s after being subjected to a maximum acceleration of about 6700 m/s² at a point 1.5 cm inboard of the rest position. The residual energy in the picking system, some 62% of the whole is absorbed in the hydrolic buffer the body and plunger of which are shown at (L).

PROJECTILE GUIDES

Labels: Weaving Manufacturing Technology | at 11/12/2010 05:21:00 PM

Introduction

The projectile guide employs support teeth which have horizontal disposed support surfaces for slid ably receiving and supporting a picked projectile thereon. In addition, alternately arranged guide teeth are provided to define a picking tunnel while also providing a lateral guide on one side of the horizontal support surfaces to prevent sliding off a projectile threat. A lateral guide surface may also be provide on the support teeth on one side of the support surface to prevent lateral movement from an opposite side of the support surface.

The limited weight and the reduced volume of the projectile make a projectile guide necessary (fig: 1 ). The projectiles therefore do not come into contact with the threads, but run inside a sort of channel composed of the thin prongs of a rake, which form reminds a semi closed hand. This rake goes up from under the threads at the moment of the projectile launch and has of course to fall back lowering itself at the slay stroke. To enable this movement, the rake is secured on the slay and is positioned very close to the reed; the rake’s laminas are not in contact with the warp, or touch it very lightly because the reed opens them the way. The latest models of the projectile machine have been equipped with new types of guide dents, which are divided and placed in alternate position, in order to reduce the stress on weft and warp threads. This permits to use in warp even very delicate yarns as for instance untwisted or entangled yarns and at the same time to cope with high quality requirements.

Fig 1: Projectile and projectile guide in a weaving machine

Projectile guide for a weaving machine

Heretofore, various types of guides have been known for use in a projectile weaving machine and particular weaving machine which employ gripper projectile. In some cases, the guides have been constructed of a plurality of guide teeth which are shaped to define a picking tunnel through which a picking element, such as a projectile, may be picked .Generally, the guide teeth have been formed with a plurals of surfaces for guiding of a projectile whereas in other cases ,an alternating arrangement of support teeth and guide teeth have been used to define the guide surface for the projectile. In addition the guide teeth have been constructed to provide an aperture on the reed side of the in order to permit release to of a picked weft yarn before the reed beats the yarn into a cloth.

Fig 2: Projectile guide on sley.

German Pat. No. 1,801,004 filed Oct. 4, 1968 describes a projectile guide which employs two bottom include guide surface and one top horizontal guide surface for guiding a projectile during picking through a shed. However, the inclined arrangement of the bottom guide surfaces leads to support forces which are considerable more than the weight of the projectile. For example, if these surfaces are inclined at an angle of 45 degrees to a horizontal , the sum of the support forces and in a first approximation , the sum of the friction forces is some 40% more than when the projectile is supported on a surface normal to the direction in which the weight acts. Further , when the sley on which the guide is mounted vibrates around the pivot point of the sley , the effect of the inclined guide surfaces is to throw the projectile from one bottom guide surface to the other and back with the projectile possibly striking the top horizontal guide because of the unsteady flight of the projectile with continuously changing impact positions on the guide surfaces and because of the associated friction forces , an elaborate lubrication system must be provided for an accurately metered supply of lubricant to the weft tunnel if wear of the tunnel is to be obviated.

Fig 3: Illustrates a view in a picking direction of a previously known projectile guide.

In another know projectile guide, as described in Swiss Pat. No. 439,159, closed guide projections have a guide surface which extends transversely to the forces associated with projectile weight. The forces with which such projectile reacts on the projectile are less in this case, so that the friction between the projectile and the guide is also less. However a disadvantage of this guide has been found to be that when the guide dips into the shed , with the guide teeth penetrating through the bottom warp plane with their opening at the front discrete warp yarns may penetrate into the interior of a guide projection. Thus, there is a risk that the warp yarns may be damaged or severed between the projectile and a guide projection. This risk is particularly great near the weaving edge where, because of the shrinkage or contraction of many woven fabrics, the warp yarns do not extend parallel to the guide projections.

Accordingly, it is an object of the invention to provide an improved projectile guide for a weaving machine.

It is another object of the invention to reduce the risk of warp yarn breakages by a projectile guide a weaving operation.

It is another object of the invention to reduce the wear in a projectile guide due to the sliding of a projectile there through.

Briefly, the invention provides a projectile guide for a weaving machine which is comprised of a plurality of longitudinally aligned and spaced apart support teeth and a plurality of guide teeth disposed in alternating relation with the support teeth. In accordance with the innovation, each support tooth has at least one horizontally disposed support surface for slid ably receiving and supporting a picking projectile thereom.In addition each guide tooth is provided with guide surfaces for preventing surface of the support teeth during picking.

The construction of the projectile guide is such that there is reduced friction between the projectile and the teeth of the guide. In addition there is less risk of a warp yarn catching inside of a guide or support tooth. Accordingly, weaving can proceed with less coolant being supplied to a weft tunnel defined by the support teeth and guide teeth and with fewer stoppages due to damage of the warp.

In one embodiment, each support tooth includes an inclined surface defining a lateral guide on one side of the support surface in order to prevent lateral sliding of a picked projectile from the support surface. In addition each guide tooth has a guide surface defining a lateral guide on an opposite side of the support surface of an adjacent support tooth in order to prevent lateral sliding of a picked projectile threat. Further, each guide tooth has a horizontally disposed guide surface in a plane above the support surface of an adjacent support tooth in order to loom lifting of a picked projectile from the support surface of the adjacent tooth.

The guide surface of the projectile guide which act laterally or downwardly on a projectile are operative merely to defect the projectile into the required direction in the event the projectile deviates from a path dead parallel to the weft tunnel. In the cases of previously known projectile guides. The lateral guide surfaces serve to support the projectile. Consequently the clearance between the guide surfaces of the projectile guide and a projectile can be considerably greater than in previously known guides. When the projectile is guided dead parallel to the weft tunnel before entering the tunnel, the only contact between the guide surfaces and the projectile is by way of the horizontal support surface of a support tooth.