Bamboo yarn
Yarns that are thin and thick, with one section stacked on top of the other, are called bamboo knots.

The bamboo knot was originally a common defect in textile production, due to some problems in the spinning process, such as drafting, uneven thickness, etc., so that the yarn local unevenness of fineness, forming a similar bamboo knot bump, resulting in bamboo knot defects, affecting the quality of the fabric.

However, when this kind of similar bamboo knot like bump in the formation of uniform distribution on the surface of the fabric, can make the surface of the fabric to form a special texture, produce a unique fabric style, to meet the requirements of people on the fabric fabric style diversity. So in the spinning process thought to make the yarn density in the direction of its length regular or irregular changes, obtained the bamboo yarn, and this yarn for the production of fabric, the formation of bamboo yarn fabric.

01
Bamboo yarn characteristics

With the appearance of uneven distribution of thickness and fineness, it is one of the most varied types of fancy yarns, including coarse detailed bamboo knot yarn, lumpy bamboo knot yarn, short fiber bamboo knot yarn, and filament bamboo knot yarn. Bamboo yarn can be used for light summer fabrics and heavy winter fabrics. It can be used for clothing fabrics and also for decorative fabrics with outstanding flower patterns, chic style and strong three-dimensional sense.

02
Bamboo yarn formation principle and method

Principle: Adding a device to the normal yarn machine to make the front roller change its speed or stop, thus changing the normal drafting multiplier and suddenly producing a thick knot in the normal yarn, like a bamboo knot, which is called bamboo yarn.

Method: The front roller stopping method is controlled by electromagnetic clutch

When spinning the base yarn: The clutch is in a suction state to keep the front roller in normal operation.
Spinning coarse section: the clutch is de-energized and the movable plate is disconnected from the static plate.
The front roller is stopped + the middle and rear rollers are still running. The sent fiber pile up between the middle roller and the front roller.
When the clutch is re-energized, the front roller starts to run again, taking the piled up fibers away and forming a bamboo knot on the base yarn.
The front roller stops for a long time? More fibers accumulate? The knot is thicker.
This method is suitable for making thicker bamboo knots.

It can also be done by sudden overfeeding of the middle and rear rollers, which will also change the draft multiplier and create bamboo knots.

Stepper motor driven front roller speed change method, servo motor driven middle and rear roller overfeed method, etc.

When using front roller speed change to produce bamboo yarn, it is sensitive and suitable for producing denser bamboo knots, and has good control of the length and thickness of bamboo knots.

Front roller variable speed? It affects the yield
The speed of the front rollers is constant from time to time + the spindle speed is constant? It also has an effect on the twist degree
When producing bamboo yarn with middle and rear roller overfeed, it is not as sensitive as front roller variable speed for producing short and dense bamboo knots, and the manufacturing cost is also larger.

Caution

When producing bamboo yarn, the centrifugal force at the bamboo section is higher, which makes the air ring bigger and smaller at the time of production. At the same time, due to the increase in the thickness of the bamboo section, through the steel wire ring has some difficulties, so should choose to use a large circle of steel wire ring.

If the front roller stops or variable speed production of bamboo yarn, the twist degree should be low.
Production of dense bamboo section, because the speed of the front roller is constantly changing, so the speed should be slowed down, otherwise it will increase the whole machine head breakage rate.
When manually stopping the yarn, it is better to stop at the base yarn part to avoid the coarse knots, otherwise the twist degree at the coarse knots will increase the head breakage when driving.

03

Application of bamboo yarn

Currently, the commonly used yarn is 12-84tex (12-83 metric). The raw materials are cotton and chemical fiber blended yarn, mainly staple fiber yarn, but also medium-length and woolen fiber, etc.

The length of bamboo knots generally cannot be smaller than the length of the fiber. Therefore, the length of bamboo knots spun with cotton fibers is shorter, while the length of bamboo knots spun with wool fibers is longer.

The thickness of the bamboo knots depends on the species.

Because the difference between the thickness of the thick section and the base yarn is too large, the twist is very small, so that this section of the yarn is not only easy to hair, and low strength. Knitted fabrics or woven fabrics made of this yarn have a rough surface and unique style. This yarn is also used to make wave yarn on fancy twisting machine, which is also called popcorn yarn because the wave shape at the thick section is very large and resembles corn.

04
The relationship between the main parameters of bamboo yarn and fabric style

Due to the special structure of bamboo yarn, the fabric style is closely related to the above 4 parameters;

Its various combinations determine its special style on the fabric surface in the following four ways.

1. Because the bamboo section of bamboo yarn is thicker, the twist added to the bamboo section during spinning is also less, and the bamboo section fiber is looser, which makes the coarse section and the fine section of bamboo yarn inconsistent in dye absorption when dyeing, and then the style of drizzle or rain will be formed according to the different length of bamboo section.

2. Different raw materials form different styles: for example, bamboo knots are more obvious in bamboo yarn fabric woven by single yarn spun from ordinary cotton and polyester raw materials.

And the use of shaped fibers such as cationic polyester, strong light polyester, viscose, etc. to form finer bamboo knots, and then twisted into a line with ordinary yarn, can be made into high-grade fabrics.

3. in the rotor spinning machine spinning 48.6 ~ 58.3tex (Nel2 ~ 10) bamboo yarn, its bamboo knots can be higher than the normal yarn 1.3 ~ 1.8 times, with the bamboo knot spacing and length of the change, can be woven with a hemp style of high-grade fabrics.

4. Using the different length, thickness, pitch and raw material of bamboo yarn, we can develop colorful and different style varieties to meet the needs of different consumers.

05
The number of base yarn and comprehensive number of bamboo yarn

The common number of bamboo yarn is usually named by the base yarn number, such as C14.5tex bamboo yarn refers to the number of normal yarn with bamboo pitch, and the number at the bamboo knot is larger. In practice, in the front roller variable speed spinning bamboo section, generally set the high speed value and twist value of the base yarn to spin the normal base yarn number before setting the low speed value and other bamboo section parameters to produce bamboo yarn.

The integrated number of bamboo yarn refers to the integrated number of base yarn and bamboo yarn. There is a difference between the integrated number designed by the process and the actual number spun, and the size of the difference between the integrated number of bamboo yarn spun by different types of bamboo yarn devices is also different. The integrated number is an important basis for the daily control of spun yarn weight deviation in production, and is also the main indicator for the costing of bamboo yarn. Some companies use the base yarn number to control the deviation of spun yarn weight when spinning bamboo yarn, so that the actual base yarn number spun is lighter and more meters of cloth can be woven. This is fine for the bamboo knot thin yarn, but for the bamboo knot thick and dense bamboo knot yarn, will make the base yarn at too fine and cause after processing more broken head.

The design integrated number refers to the integrated number of bamboo yarn in the process design. It is the weighted average of the base yarn and the number of bamboo knots in a certain cycle, using the percentage of pitch and knot length in a certain cycle as weights.

It should be noted that the total length of the yarn in a certain cycle should be calculated by the regularity of the bamboo knot arrangement.

For regularity, it is the cycle length in one cycle, e.g. five bamboo knots in one small cycle, and for irregularity, it is the total length of five bamboo knots in one cycle; for irregularity, it can be estimated according to the set average knot length, pitch and coarseness multiplier.

The actual integrated number is the actual number of spun bamboo yarn, which is different from the integrated number of the process design. Therefore, in daily production, the actual integrated number of the yarn should be controlled to reach or close to the integrated number of the process design according to the national standard of yarn, and the weight deviation should be controlled at ±2.5% for the batch and ±0.5% for the month.