Weaving machines; They are machines that create a textile surface by combining warp and weft threads in a certain order with knitting connections. Although the basic principles are the same, there are many different types of weaving machines that vary according to the manufacturer.
The main elements and systems in weaving machines:
>>>>> Bench frame (chassis)
>>>>> Motion transmission systems
>>>>> Main shaft
>>>>> Warp bridge and warp release systems
>>>>> Fabric pulling and winding systems
>>>>> Frames and shedding systems
>>>>> Weft insertion systems
>>>>> Tambourine and comb
>>>>> Edge making systems
>>>>> Staples
>>>>> Weft control systems
>>>>> Warp control systems
>>>>> Warning lights
BENCH SKELETON
The loom frame is the part on which the parts that make up the fabric are gathered in order for the machine to work efficiently. It consists of two edges connected by one, two or four beams on which all machine elements are placed. It should be capable of absorbing the vibrations caused by the mechanisms on the weaving machine chassis.
Its side edges should be strong enough to withstand the impact force and should be suitable for transportation as a whole. Placing the engine on the bench frame (as a result of the vibration of the machine causing damage to the engine and its bearings) is now abandoned. In modern weaving machines, the motor is mounted on the floor next to the loom or on a table mounted on the floor.
DIRECT MOVEMENT TRANSMISSION ON WEAVING MACHINES
direct motion system, It is a motion transmission system in which the motion from the engine is transferred to the shafts and systems via gears.. It is a system used in old type weaving machines. However, since the loss of motion is much less in direct motion transmission than in indirect motion transmission, direct motion transmission comes to the fore again.
Light benches work with a direct movement system. When the machine is stopped, the energy supplied to the motor is cut off as the motor switch is connected to the idler. When the idler is opened, the energy coming to the motor turns the motor and the machine. In this system, the gear in the engine is connected to the crank gear through intermediate gears. There is no grip in between. The motion is given from the motor pulley to the idler pulley. The clutch is on the idler pulley.
In weaving machines, it is desired that the engine speed be the same from the moment of first operation to the moment of stopping. Otherwise, the wefts that are thrown after the stop cannot be tapped strongly enough, which will cause the stop trace error.
The new type of motors, called selvo motor technology, has the ability to reach full power in a short period of time such as one engine revolution. It is the speed control unit produced as a single piece with the motor that provides this. For this reason, they are also called control motors. Super Motor (sumo) developed by Picanol company can be given as an example of modern weaving machines working with the principle of direct motion transmission.
There is no clutch belt, speed pulley, electromechanical shaft and belt assemblies in Selvo motor technology. The rate of occurrence of stance trace error has decreased significantly with the first-time cycle. In addition, weft insertion and shed search can be done more quickly.
The construction structure, which provides direct transmission of the movement, also ensures that the skeleton of the machine consists of fewer parts.
INDIRECT MOTION TRANSMISSION IN WEAVING MACHINES
It is a motion transmission system in which the motion from the engine is transmitted to the shaft and systems via pulleys and belts.. It is more widely used than direct motion transmission. The most important drawback in motion transmission provided by pulley and belt is loss of rotation. Today, 'V' belt is used to minimize this loss. Since the V-belt fits well on both sides of the pulley cavity, the speed loss is low.
MAIN SHAFT
Weaving machines have two main shafts, the crankshaft and the camshaft. The duty of the crankshaft is to distribute the movement from the engine to the weaving machine. The camshaft usually drives the shedding systems. Internal eccentric shedding systems also have a cabinet shaft parallel to this shaft. When the crankshaft makes two revolutions, the camshaft makes one revolution.
WARP BRIDGE AND WARP RELEASE SYSTEMS
The warp beam is the part of the weaving machine in the form of a large reel where the warp threads are wrapped.
The warp bridge is the weaving machine element that changes the direction of the yarns coming from the warp beam and transfers them to the fabric beam in parallel. It is in line with the fabric bridge. When the frames are aligned, the warp threads between the warp and fabric bridges are parallel to the ground. The warp bridge can be movable or fixed.
Being mobile, that is, moving towards the inside of the machine at the time of shedding, prevents the warp threads from breaking due to tension. As the weaving is done, the warp threads must be sent from the warp beam. Warp release systems are systems that ensure the delivery of warp threads from the warp beam. As the wefts are tied to the warps, the warp length on the loom will be shortened, so the warp threads wrapped in the beam are left forward and the necessary warp lengths are fed to the weaving loom.
NEGATIVE WARP ( RELEASE ) DISCHARGE EQUIPMENT
During weaving, the warp is emptied (released) in the thickness of the weft thrown by the weft. Therefore, negative means imprecise. Generally, weighted and spring systems work negatively. In this system, the rotation of the warp beam, that is, the warp release, is done with the help of warp tension. During the fabric formation, the tension of the warp threads that are pulled continuously increases gradually and this tension force turns the warp beam a little. Counterweights attached to the rope or band are attached to the outer edge of the warp beam. There is no warp tension measurement. The warp tension in the negative warp let-off system changes as a sudden decrease after a continuous increase. The period of this change is achieved by changing the location of the counterweight. However, any change in weights creates abrupt changes in warp tension. This may cause frequent and infrequent errors due to changes in the fabric line.
POSITIVE WARP ( RELEASE ) DISCHARGE EQUIPMENT
During weaving, the warp is emptied at a certain rate in each revolution of the machine, whether the weft is inserted or not. This unloaded amount is adjusted according to the weft density and remains constant until the end of the weaving. Therefore, positive systems usually consist of gears and levers. Warp threads must work under an equal tension during normal operation. This tension is very important for the lifting of the frames and the throwing of the shuttle. Positive warp release systems also take into account the warp tension on the machine. When there is any tension change in the warp, the warp bridge is affected by this change.
The warp tension is regulated by transmitting the pressure of the yarns to the warp bridge to the warp release regulators through the levers attached to the bridge.
EDGE MAKER SYSTEMS
In woven fabrics, an edge is created in order to prevent the warp threads from scattering from the edges and to preserve the form of the fabric during subsequent processes. Fabric edges are different from the ground part of the fabric in terms of warp density, color and weave. Since the weft thread is uninterruptedly unwound on the bobbin in shuttle weaving machines, the edge is formed on the fabrics by itself. These types of edges are called true edges.
In shuttleless weaving machines, after weft insertion, the yarn ends remain free on both sides of the fabric. In shuttleless weaving machines, four different types of edging can be formed on fabrics according to their usage characteristics.
CIMBARS
It is a machine element that prevents the fabric from shrinking during weaving and prevents the warp threads from breaking during the tambourine strike and ensures that the fabric width in this region is very close to or the same as the reed width. Staples are formed by arranging needle rollers on a shaft.
WEFT CONTROL SYSTEMS
Weft control systems are the systems that stop the machine when the weft breaks. Weft control in shuttle weaving machines is carried out with a part called a fork. The weft fork can be on the edge or middle of the fabric. In modern shuttleless weaving machines, weft control is done with weft sensors.
WARP CONTROL SYSTEMS
The systems that stop the machine when the warp breaks are called warp control systems. It is important to stop the machine as soon as the warp breaks, as warp breaks cause significant defects on the fabric. Warp control systems on modern weaving machines are:
Lamellar Warp Control System
Lamels are made of thin steel sheet. Each warp thread has a lamella on it. Since the lamellas can stand on the saws with warp tension, they fall down when the warp breaks. The lamella falling down closes the electrical circuit, a magnet that comes into action stops the machine. The saws in the control system consist of two parts, internal and external. The inner saw makes the right-left movement inside the outer saw. When the lamella falls on the saw, it enters between the teeth of the saw and prevents them from moving and the machine stops.
In this system:
1-The warp tension is fixed and well-adjusted,
2-The lamella weights must also be chosen correctly.
Loose warps may cause the machine to stop unnecessarily, and light lamellas may not fall, causing warp errors.
Photocell Warp Control System
Warp threads are controlled by a photocell placed on the warp bridge.
Brushed Warp Control System
In this system, a rotating brush is placed under the warps between the warp bridge and the frames. When the warp threads break, they fall on the brush. When the warps fall on it, the rotating brush stops and stops the machine.
Warning Lights
Warning lights on modern weaving machines work together with control systems. It indicates warp, weft breakage or any malfunction in the machine. Each color of the warning lights indicates a problem. The meaning of the lights may not be the same on every machine.
