In weaving, Although the fabric formation principle has not changed for years, the methods used and the drive and control forms of weaving machines have changed over time. At the end of the twentieth century, the rate of change increased continuously and the weft insertion rate, which determines the production amount of the machines, increased approximately 1950 times between 2000 and 10. The rate of increase in production rates has increased continuously until today. In the period from the beginning of the 21st century to this day, the rate of increase has increased continuously and reached a value close to the 1950-fold increase between the years 2000-10. The weaving industry sector, which was previously a labor-intensive industry, has now turned into a capital-intensive industry with modern technologies.
The basic processes of weaving a fabric are as follows;
1) Shedding, that is, the process of separating the threads into two or more layers according to the pattern in order to ensure that the weft thread is passed between the warp threads,
2) Weft insertion (weft registration),
3) Sterling (feeling), that is, carrying the weft yarn deposited on the shed to the fabric line and including it in the fabric (the line where the fabric ends after the previous weft is thrown).
The necessary units for feeding the weft and warp threads and winding the woven fabric should be available on the machine. The warp thread is usually fed over the warp beam, while the weft thread is fed by winding on bobbins (only for shuttle looms) or conical bobbins. Regardless of the weft insertion system, most single-phase weaving machines use similar mechanisms and a horizontal warp line between the back bridge and the chest bridge.
Although the horizontal warp line is the most widely used, other successful warp lines have also been developed.
In the weaving looms, after each wefting process, after the shed formation for the next weft, a new weft is deposited in the shed across the entire width of the fabric and these processes are repeated in each machine cycle. single phase and where more than one weaving process phase is present at the same time and multiple weft insertions are carried out simultaneously multiphase can be divided into two groups.
Single-phase weaving machines are divided into subgroups according to their weft insertion systems, while multi-phase weaving machines are classified according to their shed forming methods.
Good quality warp threads are needed for the successful and efficient operation of a weaving machine.
The success of the weaving process depends on the preparation quality of the warp beam attached to the weaving machine. Because each error in the warp will either stop the machine and require correction or cause an error in the woven fabric. Before weaving a fabric, the beams on which the warp threads are wound must be prepared.
For very thick warp yarns or when fabrics can be woven from filament yarns without changing the warp preparation properties, a creel that can be placed behind each weaving machine can be used economically.
With this approach, weaving efficiency is increased as frequent beam changes are avoided, but a lot of space is needed. For the majority of warp yarns, especially for sized yarns, it is more economical to prepare a warp beam and use it on the weaving machine. The purpose of most warp preparation systems is to combine the warp yarns needed on the weaving machine into one beam and warp the warp so that all the warp strands are constantly present and the elasticity of the warps as they are wound. It is to feed it to the weaving machine by preserving its values. Before this process is done, the yarns must be wound into conical bobbins, transferred to the warp beam and finally sized before being transferred to the weaving beam.
The purpose of the sizing process is to cover the warps with a protective layer in order to increase the strength of the warp threads, which are subjected to complex stresses in the weaving machine. Some thick-ply yarns and high-strength yarns can be woven without sizing.
Whether a fabric is woven on a hand loom or on the most modern high-speed multi-phase weaving machine, shed opening is essential for insertion of the weft prior to pitching and fabric formation.
The shed must be clean, that is, loose warp threads or surface hairy threads or warps catching with each other must not obstruct the passage of the weft thread or weft carrier. If the weft thread cannot be thrown without this interference, the machine will stop to correct the problem. A warp may be broken or damaged, or a faulty fabric pattern may occur.
SLIP OPENING ON SINGLE PHASE WEAVING MACHINES
In the majority of single-phase weaving machines, before weft registration starts, the upper and lower warp layers are separated and the shed is formed, and the position of the warps in the shed cannot be changed until the weft is deposited on the shed across the entire warp width.
The shedding mechanism is used to move the warp threads up or down in the order determined by the knitting pattern. During weaving, the yarns forming the warp layers can be slightly shifted relative to each other in order to ensure a good separation of the warp yarns and to prevent the adjacent yarns from sticking together (sticking to each other). However, it is obligatory to maintain an opening in the weft registration area in a way that does not prevent weft passage. The shedding mechanism chosen for a particular weaving machine depends on the pattern envisioned on this machine. Shedding mechanisms are generally expensive, and the greater the patterning capability, the more expensive the shedding mechanism will be. Some weaving machines also have technical limitations that determine the shedding mechanisms that can be fitted to this machine. Cranked, camped or dobby shedding mechanisms When used, the warp threads are passed through the strong eyelets attached to the frames and are moved up and down by the frames. All forces in a frame are moved together and all warps controlled by that frame are therefore removed in the same way.
The knitting pattern determines the minimum number of strengths needed. Warps that make the same movement are distributed across multiple frames that make the same movement, to prevent the number of strengths in one frame from becoming too large. For example, 2, 4, 6, 8 frames can be used for weaving cloth. In this case, half of the frames are lifted in each weft, while the other half is lowered.
Crank shedding mechanisms are generally limited to 8 frames, 10 or 12 frames with cams, and dobby shedding mechanisms are limited to 18 or 24 frames.
If the movement report required for a pattern is not obtained with the use of 24 frames, it is possible to control each warp yarn separately. jacquard shedding mechanisms must be used.
The crank shedding mechanism is the simplest and most positive available. It can only be used for weaving cloth in plain foot knitting. This mechanism is inexpensive, easy to maintain and maintain, and increases weft insertion speeds by as much as 10% on many high-speed weaving machines. It is not widely used due to its lack of versatility. However, it is particularly useful for many industrial fabrics since the vast majority of fabrics are woven with plain weave. Cam shedding mechanisms used with modern high-speed weaving machines have either corrugated cams or conjugate cams. Because these cams make it possible to control the frames positively. However, cams with a negative profile are still widely used for weaving light and medium weight fabrics. The cam profile is designed to give the desired frame movements according to the action plan obtained from the knitting report.
A third way to control frames is using a dobby shedding mechanism. The biggest advantage of dobbies is that the woven pattern practically does not impose a limit on the size of the report. On the other hand, it is expensive and difficult to obtain knitting patterns larger than eight or ten wefts in cam shedding mechanisms. Dobbies are easy to manufacture for a large number of frames. Dobbies are controlled by pattern chains containing rollers or links. Pattern links are selected for the frame lifting mechanism in the dobby. For long motion reports, punched cardboard or plastic cards were used instead of metal chains or heavy wooden links. In the 1990's, electronic dobbies replaced mechanical dobbies, thus shortening the time to prepare a pattern. Following the development of electric dobbies, the popularity of cam shedding mechanisms has declined. Because cams are expensive for high speed weaving machines. It may be cheaper to buy a dobby weaving machine if many cams are required due to the knitting structure or the need for frequent pattern changes. Mouth opening mechanisms are still under intensive development. Electronic control of individual frames may soon reduce the price difference between crank, cam and dobby machines. It seems more likely that developments will simplify the shedding units, reduce their price and maintenance, and make the weaving machine more flexible. If the patterning capacity of dobbies is insufficient to weave the desired designs, it is obligatory to use jacquards.. Modern electronic jacquards can operate at very high speeds and impose practically no limitations on the designed pattern. Each warp thread can be controlled separately along the width of the weaving machine and the weft pattern can be of the desired length. Jacquards are expensive, and if a large number of warp threads are to be controlled individually rather than in groups, jacquards cost as much as the weaving machine on which they are mounted.
NOZZLE OPENING ON MULTI PHASE WEAVING MACHINES
In almost all multi-phase weaving machines, more than one weaving process phase is created at any time so that more than one weft can be inserted simultaneously. In wave-toothed weaving machines, different parts of the warp layers are in different parts of the weaving process phase at any given moment. In other words, when looking at the warp layers across the width of the machine, some of the sheds are formed, while the sheds are closed in the other part, and in another part, the shed is in a newly formed or closing position. This allows a certain number of shuttle or weft carriers to move within the sheds that occur one after the other in the same plane. Weaving machines in which the shuttles move on a circular trajectory along the opening wave nozzles are called "round weaving machines". These machines are widely used to produce round polypropylene woven fabrics for sacks and bags that will carry heavy loads.
Weft insertion and scattering ( SINGLE PHASE WEAVING MACHINES )
All single-phase weaving machines are classified according to their weft insertion system.
Main methods in single phase weft insertion;
They are systems with shuttles, shuttles, hooks or water jets.
CONVECTIONAL (SHUTTLE) WEAVING MACHINES
The looms, in which shuttles are used to transport along the shed, dominated woven fabric production until the 1980s, even in countries with high wages such as the USA. Now it is not used, except for the weaving of several types of special fabrics. Despite this, a large number of automatic bobbin changing machines are still in use. However, they are quickly being replaced by shuttleless weaving machines. Shuttle-less weaving machines produce fabric with fewer errors, and fewer workers are needed for weaving and maintenance. Millions of hand looms still operate in Southeast Asia, protected by law.
Fabric production on a shuttle weaving machine It is moved along the nozzle from one side of the loom to the other by the impact mechanism located on both sides of the shuttle machine that carries the bobbin on which the weft is wound. For each weft, the shuttle suddenly accelerates and flies over the shuttle path. A weft thread is deposited on the shed as the shuttle moves along the shed. The shuttle has to be stopped quickly when it reaches the shuttle box (home) on the other side. After each weft is placed in the mouthpiece, it is included in the fabric by tamping. The comb and shuttle path is mounted on the trolley and moved back and forth together with the trolley. While the shuttle is moving along the shed, it is close to the drum frames in order to allow the shuttle to pass without damaging the warp threads. Then, the drum is moved forward to include the weft deposited on the shed into the fabric. The need for an open shed during most of the weft insertion period and the weight of the reed and the weight of the drum that carries the shuttle path impose limitations on the weft insertion speed, that is, the loom cycle. The main weakness of shuttle weaving machines is the disproportionate mass of shuttle and bobbin compared to the small mass of weft yarn carried by the shuttle and deposited in the shed. Only 3% of the energy transferred to the shuttle is used for real weft insertion. Another limitation on the speed of the machine is the necessity of making the heavy drum move oscillating. Although theoretically it is possible to reach 450 m/min weft insertion speed on wide machines, only a few machines have exceeded 250 m/min weft insertion speeds in commercial use. In looms with non-automatic shuttle, every time the weft thread on the bobbin is about to run out, the weaver has to stop the loom and change the bobbin. The bobbins must be changed when there is too little thread on them to prevent the weft from ending up in the middle of the shed and thus creating a broken weft that needs to be repaired. In industrialized countries, non-automatic and semi-automatic shuttle looms are being replaced by shuttle looms where the bobbins are changed automatically. In automatic shuttle looms, the bobbins are changed without the intervention of the weaver without stopping the machine. In order for the machine to perform the bobbin replacement process when necessary, new ones are periodically placed in the magazine to replace the empty bobbins. Magazine fillers are interchangeable with shuttle box loaders. The bobbins are brought to the counter in special boxes and transferred to the changing mechanism automatically from these boxes. Looms where the bobbins are changed instead of the bobbins when the bobbins are empty are available for very weak yarns. All these methods require winding the bobbins before they are brought to the machine. There are practically no restrictions on the weight and width of fabrics that can be woven on shuttle looms. In addition to the shuttle looms, shuttle boxes and special mechanisms can be installed in order to enable more than one color or type of weft insertion according to the pattern.
SHUTTLE WEAVING MACHINES
Weaving machines with shuttles either use a single shuttle that is thrown from both sides of the machine in turn. These shuttles are then brought to the side from which the shuttle is launched with a conveyor belt or chain. An important advantage of all shuttleless weaving machines is that the weft on the conical bobbin does not have to be rewound before it is used. This eliminates a process and reduces the danger of tangling the threads. Thus, it is ensured that the weft yarn is used while it is being produced.
In shuttle looms, the weft is divided into relatively short lengths and wound on bobbins. These threads are then woven in reverse order. This can introduce long periodic faults in a yarn.
For weft insertion in a Sulzer type weaving machine, after the weft is pulled from the bobbin and passed through the weft brake and tensioner, the weft is transmitted to the shuttle feeder placed in the shuttle holder. A torsion bar system is used in weft insertion to transfer as much energy as possible to the shuttle before the shuttle leaves the impact element (picker). The torsion bar (torsion angle) can be adjusted to feed the energy needed to move the shuttle along the guides in the nozzle and deliver it to the shuttle brake on the other side. Sulzer has redesigned the scallop and shank mechanism to achieve a more powerful and faster swivel stroke allowing more time for weft insertion. 3600 mm wide machines 1300 m/min. Narrow shuttle looms can operate at 1000 m/min weft registration speeds. Weaving machine models with shuttles are available for heavy fabrics, thick and fancy yarns and weft up to 6 colors. Machines can be fitted with all kinds of shedding mechanisms and microprocessors to adjust and monitor machine performance. It is frequently preferred to weave a certain number of fabrics side by side in a wide width machine, as the weft insertion speed increases as the reed width increases and the investment cost per unit width decreases in wide shuttle weaving machines.
HOOK WEAVING MACHINES
Hooked looms can work with single or double hooks.
On single hook machines Usually hard hooks are used and it is advantageous in weaving narrow fabrics from thick yarns. Single hook wide machines remain too low speed for many applications. In single hook weaving machines, the hook moves across the width of the loom and usually grabs the weft during the return movement and deposits it into the shed. A variation of the rigid single hook is the two-sided single hook systems, also called bi-phase hooks. These systems do not use technical (industrial) fabrics. Most rapier looms use double hooks where each hook enters the shed from one side. The hooks meet in the middle and weft transfer takes place. In the Gabler system, the first weft is inserted in turn from both sides of the machine. Since the weft is cut every two revolutions, fabric edges are formed on both sides, where the weft threads are connected in a U shape.
In today's machines Gabler system place Dewas system has received. dewas In the system, the weft is thrown from one side and cut at each machine cycle.
On double hook weaving machines flexible or rigid hooks are used. Rigid hook weaving machines require more space than machines with other weft insertion systems. Fabrics woven with double hook weaving machines range from low-density geotextile fabrics to heavy conveyor belts.
Double flexible hooks are generally used in rapier weaving machines. These machines have widths up to 4600 mm and are produced for special purposes in wider widths for industrial fabrics. Standard machines have a relatively low investment cost and are used to weave a wide range of light to medium weight fabrics. Since the weft color selection mechanism of up to eight colors is simple and inexpensive, rapier weaving machines are ideal for weaving fabrics with multiple colors or types of weft and for short runs.
They are widely used with jacquard shed opening mechanisms for weaving upholstery and trendy fabrics. Hook looms are also used in the production of some industrial fabrics.
FLUID GEL WEAVING MACHINES
Flowable gel weaving machines to carry the weft through the shed air or water used. This system requires a weft carrier or hook for weft insertion. Therefore, there is much less moving part and much less mass to move.
Although most of the yarns can be used in air-jet looms, water-jet weaving machines are only suitable for water-repellent yarns.
On water jet benches In order to carry the weft across the entire width of the shed, there is usually only one nozzle on the side where the weft is thrown. Therefore, machine widths are limited to approximately 2 meters.
Single-level air-jet weaving machines have been commercially successful in widths up to 1700 mm, as the control of the air flow is more difficult than the control of the flow of pressurized water. For larger machines, reed transverse auxiliary nozzles are placed in order to ensure a smooth weft thread movement across the machine width. Although wide-width air-jet machines can theoretically be produced, commercially, single-width machines are more attractive and machine widths are limited to 3600-4000 mm reed widths. Compressed air is expensive to produce and difficult to control its flow. For this reason, it is necessary to limit the air flow in order to carry the weft through either the special air channel or the channel formed in the card with a special profile.
Air jet looms It has developed rapidly since it came into commercial use in large quantities in the 1970s. Today, air-jet looms can weave the vast majority of woven fabrics and dominate the mass production of relatively simple fabrics.
Air jet weaving machines 3000 m/min. They have reached the weft speed. This speed is about twice the speed achieved with any single phase weft insertion system and is still in intensive development effort. The air-jet system is highly competitive with the investment cost per meter weft thrown.
Air-jet weaving machines with automatic weft repair system can repair the majority of weft defects that occur between the main nozzle and the other side of the fabric. This unit removes the broken weft thread from the shed without damaging the warp threads and restarts the machine. If the machine cannot detect and correct the error, it generates a signal to warn the weaver.
Since weft stops constitute the majority of machine stops in air-jet weaving machines, this system reduces the workload of the weaver by more than 50% in most cases. With this system, the quality of the woven fabric is improved and the lost time that occurs when more than one machine stops at the same time is reduced.
OTHER MECHANISMS AND ACCESSORIES USED IN SINGLE PHASE WEAVING MECHANISMS
WARP FEEDING AND WARP RELEASE MECHANISM ( MECHANISM )
Warp threads are fed to the weaving machine from one or more weaving beams. In special cases, it is possible to feed directly from the bobbins in the creel. In order to ensure that all the wires are of the same length during the discharging of the warp threads from the beam, the warps should be wound evenly in the beam and with the same tension.
As the beam diameter increases, the wound warp length increases and less beam change is required. However, it is imperative to balance the larger warp tension variations.
Beams of different diameters can be attached to different weaving machines. Larger diameter beams are required for weaving industrial (technical) fabrics or fabrics using thick warp yarns such as denim. These beams are placed in a separate beam creel placed behind the counter.
Beams up to 1600 mm diameter can be used with this type of beam creels. The warp width on the beam should be at least as much as the yarn width on the reed.
If the warp width exceeds 2800 mm, more than one warp beam is used to facilitate sizing and beam transport. If more than one warp beam is used in a fabric, the beams should be prepared under the same conditions in order to prevent differences that cause fabric defects after the finishing process.
Warp tensions fed from different beams during weaving have to be carefully controlled and this process has become simpler with the use of electronic sensors.
If the fabric to be woven needs warp threads in thread counts that differ greatly from each other, or if different parts of the warp have significantly different fold values from each other, it is necessary to work with more than one warp beam in parallel. These beams can be placed one above the other or one behind the other on the weaving machines.
During weaving, the warp release mechanism feeds the warp thread to the weaving area at the required rate in each machine cycle. Before weft insertion, the warp release mechanism should keep the warps in equal and uniform tension so that the warp threads can be easily separated into two or more layers while the shed is being formed.
In this way, the necessary warp tension is maintained during the heeling of the last weft. The warp let-off mechanisms were mechanically controlled by measuring the tension with the displacement of the rear bridge, but now the tension is measured by electronic sensors and the warp let-off is controlled by separate servo motors.
FABRIC DRAWING DEVICE ( MECHANISM )
Fabric pulling mechanisms are used to pull the woven fabric forward at a constant speed. The fabric draw speed controls the weft density and must be regular to avoid weft density changes and other fabric defects. In most weaving machines, the fabric pulling mechanism also controls the winding of the woven fabric onto the fabric roller. If it is necessary to prepare large diameter fabric cylinders in the weaving of heavy fabrics, a separate fabric winding unit is placed outside the loom body.
AUTOMATIC STOP DEVICE
The first group, warp protection devices, applies only to weaving machines with or with shuttle. These devices prevent damage to the machine when the shuttle jams and many warps break off.
Warp stop devices stop the weaving machine when the warp breaks. When the warp threads break, the lamellas fall down and the warp stop device is activated. Lamels are used with mechanical or electrical warp stop devices. The warps must be sized properly so that the warp threads are not damaged by the lamellas.
Electronic warp stop devices, which do not have physical contact with the warp yarns, are especially used for thin filament yarns.
Weft stop devices are used to start the weft changing process in weaving machines with automatic shuttle and to stop the machine when the weft thread breaks during weft insertion. In air-jet weaving machines with an automatic broken weft repair system, the weft stop device also starts the weft repair process.
QUICK TYPE CHANGE
The rapid type change system (QSC), first exhibited by Picanol and now owned by all machine manufacturers, greatly reduces the time the machine has to be stopped during a warp change. The warp beam, back bridge, warp stop, frames and reed are housed in a module that separates these parts from the body of the weaving machine.
This module is carried to the drawing-in and work tie sections with a special transport unit and preparation is made for warp change and brought back to the weaving machine. Thus, up to 90% of the work done on the normally stopped weaving machine is eliminated in the warp change process and the weaving machine efficiency is improved. With this system, better machine performance and fabric quality are obtained as the reeds and frames will remain cleaner.
of a weaving machine comb width It should be wider than the width of the fabric to be woven on the comb or equal to the width of the comb. The warp width in the reed should cover the fabric edge widths and the auxiliary edge warps. If the machine width is narrow, the fabric cannot be woven in this machine.
In general, it is not possible to increase the card width of a machine. It is usually possible to weave heavier fabrics while the existing machine width cannot be exceeded. In Sulzer shuttle weaving machines, the fabric can be woven by reducing the width up to 50% of the machine width.
Different weaving machine manufacturers and their different models of weaving machines have different arrangements for weaving fabric at lower widths than the machine width. Some companies only allow a width reduction of 200 mm. Considering the possible changes in material and fabric types, this value is insufficient.
It is most economical to use most of the reed width, as weaving fabric at low widths can reduce weft registration speeds. Wide width machines are likely to have higher investment and operating costs. In some cases it is economical to weave a certain number of fabrics side by side on one machine. On a large Sulzer shuttle weaving machine, five, six or seven towels can be produced, each with its own roll-up edges.
According to certain rules, the warp threads are passed through the eyes of the frames and between the comb teeth. levy It called.
What are impacted teeth?
When one or more teeth fails to grow in the correct position and is therefore held below the normal gum line, it is called an impaction. This can be complete, such as completely unerrupted (buried) third molars (wisdom teeth) or partial when just part of the tooth is visible in the mouth.
Why are impactions important?
For best function and appearance the teeth should grow in a healthy alignment. When one or more teeth is impacted, this can affect the function of that tooth but also the function and appearance of other teeth.
Whether all impactions should be treated is still controversial and your dentist and oral and maxillofacial team can explain the advantages and disadvantages or treatment for you, which is usually surgical.
The first stage of the extraction process strength gain, The power of the warp yarns, which are connected to the frames, is passed through the eyes of the power wires in accordance with the drawing-in plan with the help of the power awl (which will draw the power).
The second stage is dredger. Reed drawing-in is the process of passing the warp threads through the gaps between the teeth of the weaving reed according to the reed plan by using the reed awl (comb puller).
A marking system that shows at least how many frames a weave can be woven and which warp should be in which frame. extraction plan is called.
The drawing plan is drawn on the basis of the report of the knitting to be woven. The basic rule in drawing-in plan is to determine the warps that make the same movement in the knitting pattern and to show that these warps belong to the same frame. The method generally used in drawing the drawing plan on the pattern paper is to place the drawing plan above the knitting report and to leave a line for each frame. The square at the intersection point of the column showing the warp thread and the row showing the frame it belongs to is filled in. The same process is repeated for all warps in the knitting pattern and drawing-in plan is drawn.
While drawing the plan; Numbering of frames can be done in two ways, depending on how the weaving machine or sample loom works.
For example; Since the odd-numbered warp threads that make up the plain weave make the same movement, that is, the same connection, they are gathered in the same frame. Similarly, even numbered warp threads form groups and take place in a separate frame. Since the plain weave pattern has two different warp movements, the plain weave is woven with at least two frames. In this case, the number of frames required for any weave to be woven is equal to the number of different warp movements in the weave pattern.
From the furthest frame to the fabric When numbered from beginning to end, each line from top to bottom represents a frame on the pattern paper. The square at the intersection point of the column showing the warp thread and the row showing the frame it belongs to is filled in. While drawing out the drawing-in plan, the warps that make the same movement can be distributed to more than one frame in order to reduce the load on the frame.
In this case, the number of frames should be a multiple of the number of warps in the knitting pattern. For example, plain weave can be woven with 2, 4, 6... frames instead of 8 frames. However, warps with different connection types cannot be gathered in the same frame. Different drawing-in types have been created in order to increase the pattern capacity in dobby fabrics.
Row drawing (flat drawing): The warps in the knitting pattern are passed through the strengths from the first frame to the last frame used. The process is repeated until the warp threads are finished by returning to the first frame.
Skip drawing: It is the drawing-in system used to allocate the yarns to other frames if the number of yarns falling on one power is more than one or if the number of yarns falling in 1 cm per frame is more than normal. It is generally preferred in tissues derived from plain oil.
Although there are two basic movements in the fabric, the threads are passed by skipping the frame and distributed into four or eight frames. Skipping is insufficient in the qualities where the warp threads have a high risk of entanglement. In this case, it is necessary to move the threads further apart from each other. The threads are passed as far away from the power as possible, such as a satin weave. This drawing-in system is called satin drawing-in.
Broken (herringbone-cut) file: In weaves such as herringbone and broken twill, it is seen that the same movements are repeated in a certain order to the right or left of a default axis in the weave pattern. According to the drawing-in principle, since the yarns that make the same movement must be in the same frame, broken paths that are compatible with the knitting occur in the drawing-in report in the schematic representation.
Group drawing: It is a type of tahar that is arranged separately in groups according to the weaves used together. It is used in very wide-reported knits, in knits where the same movements are repeated in different directions.
Mixed yield: It is the drawing-in method used in wide-reported knits such as crepe, where the yarns repeating the same movement do not allow grouping. It is arranged according to the principle of passing the threads making the same movement through the forces in the same frames.
Double-deck (two-track) feeder: It is a drawing-in system used to reduce friction in fabrics that require two or more warp beams, because the milking speeds of the warp threads are different in fabrics reinforced in warp direction. Drawings of two different warps are shown in two rows on top of each other with a space between them.
Manual extraction process; It is done in a controlled manner by two workers. In the manual drawing-in process, all the frames are hung on the drawing-in table. According to the plan, the worker behind the stand, called the drawing backer, hands the threads one by one to the worker, who is standing in front of the table, one by one, called the drawing-in leader. The draw-in pioneer examines the strength of the warp threads given by the power crochet and the draw-in backer one by one. The power board is started from the left side of the first frame. What needs to be considered in this process is to act in accordance with the drawing-in report. In the second operation, the reed of warp threads taken from the reeds passing through his teeth.
The materials used in making the drawing;
1-Drawing stand; These are the tables that provide a simple working environment consisting of metal parts on which the drawing process is done.
2-Frames; They are the most important parts used in weaving machines to make the desired up-and-down movement (suitable for the weave of the fabric to be produced) of the forces on it in the opening of the shed and the warp threads passed through the eyes of these forces. The strength of the fabric to be woven varies according to the knitting report. The number of forces to be loaded on the frames may vary according to the frame width and the type of weaving machine.
3-Powers; They are metal parts that enable the warp threads to be attached to the frames in groups or are free in the jacquard system. They are metal wires or plates on which the warp threads are passed through the hole called the power eye. In order for the warp threads to form the shed, they must be oriented up and down according to the knitting movement. It is a drawing element that has a high importance in the formation of the shed, which ensures that this movement is delivered to the warp through the frames.
4-Lamels; Lamels are part of the warp control system. Lamel throwing is also done by the collectors. Lamel is thrown on all warps, one for each warp wire. Lamel throwing is done after the warps are taken to the machine and tied. In order to control the breaks of the warp threads, they work in combination with a mechanical or electrical system and ensure that the weaving machine is stopped as soon as the warp thread breaks. Lamellar structure is produced as open or closed bottom part. They perform their duties on metal sheets called saws. It is possible to attach the types with open bottom to the machine after the drawing-in process is finished. Closed types should be done before starting the drawing-in process, before the warp threads are passed through the lamellar eyes.
5-Weaving Comb; It is the part of the weaving machine that ensures the uniform and homogeneous distribution of the warp threads to the fabric to be woven. It provides the adjustment of the width and density of the fabric. They are made of thin metal plates attached at their ends to various metals and plastics.. The space between the two metal plates is called the comb tooth. The number of this space in 10 cm is expressed as the comb number.. It helps to define the combs according to the frequency. The increase in the frequency of the comb means that the ratio of the density of the fabric to be produced is higher. The comb is a mobile auxiliary part for the weaving machine, which is made with interchangeable frequencies. While choosing the reed number, the width of the fabric, the warp density, the knitting pattern, the warp color pattern, the thickness of the warp threads and the thickness of the knots should be taken into account.
6-Comb and Strength Crochet; It is an auxiliary drawing-in element made of metal, which is used in the weaving machine to pass the warp threads through the reeds and strengths in the weaving preparation for breaks that may occur during production and while drawing-in. They are called comb pull and pull power. They are hand tools that each drawing-in and weaving element should have with them during work.
Cleaning and Maintaining the Frame, Strength, Comb, Coverslip and Extraction Table;
The moment of stopping of the weaving machine during the operating period is only when the machine is taken into maintenance or for any reason. During long-term operation, the parts on the machine need to be cleaned continuously and in a short time. Weaving frames can wear out or break over time due to the constant movement of the shed and the weight it has taken on due to the warps. The loosening of the fixing screws of the frames should be checked and replaced.
Power and cleaning of the lamellas before the drawing-in process can be done very simply and precisely in modern cleaning machines. In these machines, the power wire and lamellas are cleaned with improved brushes and circulation system, fully automatic rinsing and drying with hot air.
During continuous friction of the weaving machine reed with warp threads, clogging may occur in areas that do not work according to the type of raw material, that is, the thread does not touch while passing. It can also be deformed due to the humidity of the environment. The cleaning of the comb can now be done on the counter in a short time with automatic cleaning machines. With the combination of steam and cleaning liquid and the optimum position of the injectors in these machines, effective cleaning is achieved with minimum water consumption.
On the other hand, in small-scale enterprises where the drawing-in process is carried out, these cleaning operations can usually be done manually with compressed air, brushes, rags and other auxiliary cleaning materials.
Manual Lamella Assembly
It is the process of passing warp threads through lamellas arranged on metal sheets called saws. In the open bottom of the lamellas, the warp thread is passed through the hole of the lamella and left in its slot on the saw. The lamellas with a closed bottom are first passed through the saws and the warp thread is passed through the lamella eye while the lamellas are on the saw.
Manual Power Drain
When drawing power manually, there is a need for the cooperation of two elements. In the task distribution, the first element is the process in which the first element complies with the order of strength (including the frames) according to the knitting report, passes the power in his hand through the eye of the crochet, and pulls the warp thread to be given by the second element. Although the procedure is simple, it requires great care. Resolving possible mistakes will cause a waste of time. In addition, non-compensation will cause the image of the fabric to be woven to be produced in a structure other than the desired weave.
The comb, which ensures that the warp threads are compressed onto the fabric surface after they are passed through the mouthpiece opened according to the knitting report, is located on the mechanism called the tee. One or more warp threads to be passed through the reed to be used are at the beginning of the important processes that should be considered after the necessary calculations. In addition, the comb should have sufficient capacity considering the position that the total number of warp wires passes through one or more.
If there will be excess in the width of the comb on the comb, this part is not left on one side of the comb, this gap is calculated and left equally on both sides. The width used on the reed for warp threads is called the useful reed width. After the necessary calculations for the card, the card drawing-in is carried out by starting the warp threads from the left or right side by using the reed drawer.
drawing machines Conventional cardboard drawing-in machines are also used in enterprises. For this type of drawing-in machines, there are dobby cardboards used in shedding systems in weaving machines. The task of these cardboards is to determine which frame will have the warp thread on the drawing-in machine by processing the knitting of the fabric to be woven on the endless cardboard. The drawing-in cardboard to be prepared according to the weave of the fabric to be woven is mounted in the cardboard slot of the mechanical drawing-in machine. With the action taken in line with this report, the force passed through the warp thread is added to the appropriate frame with the help of needles. There is no computer-aided work in the drawing-in process to be performed on mechanical drawing-in machines. Generally, the majority of transactions are carried out by working personnel. The mechanical nature of the drawing-in machine causes a loss of time compared to modern drawing-in machines.
Adjustment and Maintenance of Drawing Machines;
It is possible for the machine to work efficiently and effectively by making general maintenance and adjustments in the drawing-in machines. The factors to be considered are the periodic lubrication of the necessary parts, the timely replacement of the necessary parts and the timely maintenance of the required parts in the periods determined by the manufacturer.
In modern drawing-in machines, periodic controls of the general mechanical drawing-in machine and separately the electronic and computer-equipped parts of the drawing-in machine and the replacement of the necessary parts are in question.
Drawing in a Drawing Machine;
Modern drawing-in machines are manufactured in such a way that they can draw in lamellas, forces and card at the same time.
The warp remains in the drawing-in carriage throughout the drawing-in process. It is fixed from above and below with the help of clamps. After the process is completed, the drawing-in car is driven into the workbench and connected to the drawing-in machine.
There is an electronic screen on the machine where all processes are followed during the drawing-in process. As a normal drawing-in principle in the machine, a warp wire is passed through each power eye. However, if a different number of warp wires will be passed through the power eye on the edges, this instruction must be entered into the machine by the worker.
A flexible awl is used for the process of passing the lamellar and strength eyes of the warps. Yarns, lamellas and power are taken by the holders one by one, they are made ready for the process and their drawing is done. The drawing plans can be given to the machine electronically by transfer diskettes or by the central transfer network. This information is scheduled and maintained by the control terminal. After the drawing-in process is completed, the drawing-in machine is disconnected from the system, the warps are placed in the weaving machine. This system can also be used for disassembly and transportation of weaving machines.
Conditions to be Considered During the Operation of the Drawing Machine
Undesirable errors may occur due to various reasons during the drawing process. These are the errors such as cross error, lamellar misalignment skipping error, drawing-in error, card-in-drawn error and comb scar. These errors are generally encountered in the manual drawing-in process. Considering these errors in the drawing-in process with the machine, it will be ensured that quality products can be produced as a result of more precise work. In mechanical drawing-in machines, it is imperative that the drawing-in element constantly monitors the power of the drawing-in and the card drawing-in process and solves the errors instantly.
Major checks to be made on the fully automatic drawing-in machine:
- Checking the yarn detectors,
- Control of lamellae,
- power control,
- Control of the drawing needle
- Control of the weaving reed,
- Draw-in control of warp ends,
- Control of report repetitions.
Semi-automatic drawing machines
These systems are used instead of one of the two workers required to transfer the power of the warp threads in the weaving to the frame lamellas and reed. When some special transport systems are added to this, the physical force required is greatly reduced and other parts of the weaving machine (frames, power attachments, lamellas and reeds) are both protected and a high quality warp system is brought to the weaving circle. Another advantageous aspect of this system is minimizing the amount of ends down in the weaving.
Warp yarn drawing-in machines
This machine acts as a "pioneer" machine. Therefore, it is a system that separates the yarn to be drawn in and feeds it about 10 cm away from the layer in the warp beam. The machine stays in this position for a while until the yarn is pulled by holding it with the drawing-in hook, and then it is immediately brought to another yarn. The time required for this whole process is only 0,6 seconds. The machine has a structure suitable for working with various yarns between 1,6 and 250 tex. It can be used with or without a cross comb. Since 1987, "contactless" electronic control systems have been installed on all machines in the drawing-in plants. In addition, thanks to the signal produced by a special system, the activation of the next device (eg lamella or counter mechanism) is guaranteed. Therefore, malfunctions that may occur due to looseness in the warp threads or other reasons do not seem to prevent the equipment from working. Stepless adjustment of the feed and working speed is possible.
Parts found in a semi-automatic drawing-in system:
- Warping machine and crossing device,
- Lamel feeding apparatus,
- drawing table,
- Warp beam bedding car,
- It is a carding machine.
ANALYSIS OF THE FABRIC TO FIND THE DRAIN PLAN (WAVING)
Analyzing a fabric; is to find the yarns, knitting, yarn density, drawing-in and the whole structure created by the dobby pattern plan. The easiest way to analyze the fabric is to use a loop or pull out the thread. To find out how a fabric was woven and what type of loom was used, it is important to find a report of the fabric's pattern in the width and length direction. Then this can be clearly marked and the entire area contained within these marks should be analysed. This can be a long and tedious process, because the first thing to do for this job is to mark the movement of all warp threads in the fabric on special pattern paper. Each weft thread is examined by working from the left to the right of the report and from the top to the bottom or from the bottom to the top, and the spot where each warp thread is seen on the special pattern paper is shown by filling in a square. It is convenient to use a needle to separate the threads properly. After the fabric pattern is determined in this way, drawing-in and dobby pattern plan can be found.
In a small sample of fabric, it can be difficult to tell which is the warp thread and which is the weft thread. If the sample has an edge there is no difficulty, but if there is no edge there are some helpful guiding factors.
The warp thread is usually the stronger thread, and if the fabric consists of cotton or rayon threads, it would be more accurate to assume that the cotton thread could be the warp. The number of threads used horizontally and vertically also forms a guide, and the larger one is usually the warp.
Warp threads are generally more twisted, and if a single ply yarn and plied yarn are used together, the ply yarn is the warp yarn. The pattern paper on which the fabric pattern is found and drawn is placed under another pattern paper in order to find the drawing. The first vertical line on the left side of the pattern paper on which the pattern is drawn is accepted as the first warp wire and the bottom left square is filled in the pattern paper to be used for drawing-in, which shows that the first warp wire is passed within the frame of the number 1.
The second vertical squares line on the pattern paper is examined and if it is different from the first line, it means that this warp wire is formed within the framework of another strength. This is also marked by filling in the square number two on the pattern paper on which the drawing is drawn, and all other same vertical lines will be passed to this power frame. If the third vertical line is different from the first two, this strength of three is indicated by filling square number three as the warp wire threaded into the frame, and its values on the fourth vertical line will be like.
This method is repeated throughout the entire report, addressing each vertical line of the drawing paper and filling in its place on the drawing paper.
It is possible to find the dobby pattern plan when the drawing is completed. This plan will be throughout the report, and the more power frames it will have, the more solid it will be.
The dobby pattern plan is added next to the fabric pattern.
WEAVING, HOUSING WARP (WAVING);
In order to control the warp threads one by one during the weaving process, they must be arranged in a lamella, they must be passed through the forces to form the desired shed, they must be passed through the comb to form the fabric of the desired width and weave at the desired frequency.
All of these processes are called drawing-in.
In the drafting process; The warp threads are passed through the eyes of the powers in a sequence determined according to the weaving weave so that they can form a shed.
This processing power is called drawing. In order for the warp threads to be woven at the desired width and frequency, they are passed through the comb teeth in a certain order.
This process is called carding. In order to control the breaks of the warp yarns during weaving one by one, the process of arranging a lamella attached to each yarn is also considered as a drawing-in process.
The making of the power plant; In order for the shed formation, which is one of the basic weaving processes, to take place, the warp threads must be passed through the strength wires.
The power of the warp threads is passed through the eyes of the wires in accordance with the drawing-in plan extracted from the weaving weave.
In eccentric and dobby weaving, the power wires are attached to the frames. In these systems, the power draw-in can be done on the weaving machine or in a separate place manually or with automatic drawing-in machines.
Since there are no frames in jacquard weaving machines, the drawing-in process is done on the weaving machine.