Raising, also known as raising, napping or brushing, is a process in which the fibers of the lining yarn (napping yarn) in the knitted fabric are drawn out to form a layer of fluff on the surface of the fabric. The purpose of raising knitted fabrics is to improve the style and appearance of knitted fabrics and give them a wooly feel. Enhance warmth retention, improve fluffiness in appearance, make fabric thicker and softer to the touch.
1 Raising and finishing equipment
The napping and finishing of knitted fabrics is carried out on a steel wire napping machine. Steel wire raising machine is also called steel needle raising machine or steel wire raising machine or napping machine. Its main body is a large roller arranged by many small rollers wrapped with card clothing.
The raising of fabrics is mainly achieved by the relative movement between the curved card clothing (or bent card clothing) wound on a small roller and the cloth surface. There are different types of steel wire raising machines, which can be adapted to the raising of various fabrics and different product varieties. The only difference lies in the form of the card clothing and the relative movement relationship of the raising.
The card rollers of the steel wire fleece machine used for raising knitted fabrics have two forms. They are only the same in number and are arranged staggered on the large roller.
A kind of card clothing roller is called a pile card clothing roller, which is wound by a bent-foot card clothing with the hook angle direction consistent with the direction of the card clothing roller. It is also called a counter-needle roller. It is generally represented by CPR; the other is called carding card clothing roller, also known as clockwise needle, generally represented by PR. The old-fashioned fleece machine has straight-foot clothing, while the new fleece machine has curved-foot clothing, and The direction of the barb bending angle of the steel needle is opposite to the direction of the card cloth roller. A raising machine in which both CPR and PR are wound by curved pin clothing is called a compound wire raising machine. The structural diagram is shown in Figure 1.
The compound steel wire fleece machine has good fleece effect and a wide adjustment range. It is suitable for processing a variety of products. However, the structure and operation are slightly complicated, and it is currently widely used. Old-fashioned steel wire fleece machines are still in use, such as the Z851 type. The difference from the compound steel wire fleece machine is that its PR is a right-angle card clothing. Its structural diagram is shown in Figure 2.
Figure 1 Schematic diagram of compound steel wire fleece structure
1-tension roller 2-cloth feed roller 3-Dehair roller 4-cloth outlet roller 5-large pile roller 6-card cloth roller 7-fabric
Figure 2 Schematic diagram of Z851 steel wire raising machine
1-Guide roller 2-Tension frame 3-Drying cylinder 4-Brake roller 5-Feed roller 6-Large roller 7-Straight needle roller 8-Loop needle roller 9-Sending roller 10. 11 – cloth guide roller 12 – lint removal roller
The large raising roller is the key device of the raising machine and consists of a large roller and a needle roller. 20 to 40 needle rollers (common ones include 20, 24, 30, 36 and 40 rollers) are mounted on bearings on the large drum.
CPR and PR needle rollers are arranged alternately on the large drum. The three are driven by different transmission systems (the speed can be adjusted and controlled independently), so that the needle rollers It not only revolves with the large roller, but also rotates, forming differential micro-motion. The fabric is covered on the needle surface of the card roller. By adjusting the speed between the large roller, the card roller and the fabric, the fabric can be carded. Or fluffing effect. There is a straight needle roller 7 under the large pile roller, which can clean the fluff in the needle roller. It is called a cleaning roller or a “dust removal roller”. The brushed fluff can be sucked away by the suction pipe at any time.
2 Analysis of the fleece effect
The fleece function of the steel wire fleece machine is It is formed by the differential micro-motion caused by the cooperation of the fabric traveling speed, the linear speed of the large pile roller, the linear speed of the needle roller, etc. Their speeds can be adjusted and controlled separately to find the best conditions for pile.
1. Traditional steel wire fleece machine
The running direction of the fabric in the fleece machine and the fleece size The rotation direction of the roller is opposite, and the running speed VF of the fabric is less than the linear speed VD of the large pile roller, that is, VF < VD. The needle tip direction of the looper roller is the same as the running direction of the fabric, and the rotation direction of the straight and looped needle rollers is the same as the running direction of the fabric, such as As shown in Figure 3.
Figure 3 Schematic diagram of the function of straight and curved needle rollers
1-Fabric 2 -Needle roller 3-big roller
If the straight needle roller only revolves with the large pile roller but does not rotate on its own, then the relative speed of the needle tip movement speed of the straight needle and the cloth surface is VD+ VF, at this time, the straight needle only brushes violently from the cloth surface, acting as a brush, and the direction of the brushed hair is opposite to the direction of the fabric; when the straight needle roller starts to rotate and turns in the same direction as the fabric, the straight needle’s bristles The effect begins to become gentle. If the linear speed of the straight needle roller is equal to VD+VF (offsetting the revolution linear speed), there will be almost no brushing effect. If the linear speed of the straight needle roller is greater than VD+VF, the brushing effect will gradually increase. However, the direction of the brushed pile is opposite to the running direction of the fabric.
When the looper roller only revolves with the large pile roller and does not rotate on its own, it can be seen from the needle tip direction in the figure that the looper roller The roller does not play the role of pulling the thread, but only plays the role of brushing, and the direction of the brushed hair is opposite to the direction of the fabric running; when the looper roller starts to rotate and its direction is consistent with the direction of the fabric running, the brushing effect gradually decreases, When the linear speed of the looper roller is equal to VD+VF, the looper roller approximately rolls on the cloth surface, and its needle tip motion trajectory is a hypocycloid, because the needle tip is slightly inserted into the fabric surface andThe tip has a slightly smaller hook, and the softest pile has begun to appear at this time. When the linear speed of the looper roller is greater than VD+VF, the raising effect is enhanced, and the direction of the pulled out fluff is consistent with the running direction of the fabric.
In actual fleece finishing, the straight needle roller plays the role of brushing and the curved needle roller plays the role of brushing. Since the speed of the straight needle roller, curved needle roller, large pile roller and fabric can be controlled and adjusted separately, the pile effect can be adjusted to the best state according to the requirements of different fabrics and different pile varieties. Various types of automatic control raising machines developed in recent years have overcome the previous experience-based adjustment of the raising operation of the raising machine, and use the automatic control system to maintain the raising in the commanded working state, thereby achieving the ideal raising effect.
2. Duplex steel wire fluffing machine
Duplex steel wire fluffing machine When the machine is working, the fabric running direction is the same as the direction of the large pile roller, and the fabric running speed is smaller than the linear speed of the large pile roller (as shown in Figure 4). As mentioned above, since the running speeds of the large pile roller, clockwise roller, counter-needle roller and fabric (represented by VD, VPR, VCPR, VF respectively) are adjusted independently, then by controlling the speeds of each other, they can maintain a certain This relationship can determine the pile function and effect of the pile card clothing. The analysis of the fluffing effect is as follows:
Figure 4 Working diagram of the compound steel wire fleece machine
1- Fabric 2-Clockwise roller 3-Counterneedle roller 4-Napping large roller
There are three situations for counterneedle roller (CPR):
(1) When VCPR>VD-VF:
The counter-needle roller hook is inserted into the fabric, and the relative movement causes relative displacement, causing the hook to The thorns then move from the inside to the fabric surface and bring the fibers out of the fabric surface to complete a raising process. The strength of the raising effect depends on VD-VF. If the difference is large, the raising force will be strong, but the fabric will be easily damaged.
(2) When VCPR=VD-VF:
There is no relative movement between the counter-needle roller and the fabric, and the hooks are inserted into the fabric After the synchronous operation, it is extracted from the fabric in its original state without any lint effect. This is called the zero point.
(3) When VCPR<VD-VF:
The back of the counter-needle roller hook contacts the fabric and presses the fluff To one side. When the barbs leave the fabric surface, the relative movement causes the barb tips to comb the fluff on the fabric surface, completing a combing process. At this time, the counter-needle roller plays a combing role.
Similarly, the clockwise roller is opposite to the counterneedle roller and has three functions, that is, when VPR>VD-VF, it plays a carding role; when VPR=VD-VF It also acts as a zero point, and only has a velvet effect when VPR<VD-VF.
As can be seen from the above, by controlling the speed parameters, the card clothing roller can be used for both raising and carding. When it is close to the zero point, the relative movement between the barbs and the fabric decreases, and the raising and combing effects are weakened; when it is far away from the zero point, the relative movement between the barbs and the fabric increases, and the raising and combing effects are enhanced. Therefore, according to the different requirements of the product, the raising force can be adjusted according to the zero point position to meet the requirements for the suede specifications.
Used together with clockwise and counter-needle rollers, the raising machine has nine working states, as shown in Table 1. Among them, the first three are widely used in the actual production of knitted fabrics. Powerful raising is suitable for polyester filament and other products that require deep threading. Carding raising can comb the fluff of plush fabrics in one direction, while ordinary raising can be used for general raising finishing of cotton and wool knitted fabrics.
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