In addition to the instrument measurement, cotton fiber length inspection involves length sensory inspection, especially the acquisition inspection by farmers, the acceptance inspection of the cotton collection station and the ginning factory, which is still the main inspection method in my country. The length of the hand of the cotton inspection technician is a basic skill. If the length of the hand is accurate, fast and good, the standard can be correctly implemented and the interests of farmers and merchants can be safeguarded. Practice has proved that it is not an overnight thing to do well in the length of the hand. It takes a lot of hard work. It is a technology and an art.

One, cotton fiber hand pull length movement specification

The length of the hand pull generally goes through the process of not coming to the meeting, from knowing to finishing. Some people may master this technique very well after one or two years of hard training, and some people are also very hard, even not learning well for many years, because the basic movements of the opponent's length and the essentials of the movement are not really mastered , To learn this skill need to start from the following aspects:

1. Basic movement of pulling length

The length of the hand pull is generally the standing posture of the human body, the body is upright, the shoulders are parallel, relaxed, the arms are bent at 90 degrees, the arms are leaned on the waist, the wrists are facing forward, and the hands are close. The action of the finger is that the first joint of the thumb is aligned with the first joint of the index finger, and the first joint of the index finger is aligned with the second joint of the middle finger, ring finger, and little finger, parallel to the front and back, and parallel to the top and bottom. Pay attention to the tip of the index finger and the thumb The joint line between the first section and the second section is parallel, do not exceed, and do not drag, the fingertips of the thumb should not be warped, and the joints should not be upward. The first section of the thumb should be flat on the index finger. In one section, hold the fiber tightly. The first section of the middle finger, ring finger, and little finger are bent in the palm of your hand, forming a fist shape. Check whether the basic movement of the hand is standardized. The key is to see whether the five fingers clasped on the desktop are on the side of the thumb and the back of the other four fingers. Touch the desktop. The length of the hand pull is generally taken by pulling three (fiber) methods, that is, drawing from the first fiber, transitioning the second fiber, and forming the third bundle of cotton. The fiber extracting action mainly depends on the thumb and wrist. Only when removing impurities, the middle finger can move, and the other fingers generally do not move.

2. Hand pulling length operation process

The first is the preparation work. The sampling should be about 15 grams. Pay attention to the direction of the natural arrangement of the fibers. Use two hands to tear the cotton sample into two, and then combine them into one. Put two pieces of cotton on the left hand. Note that the two cotton piles are kept parallel upwards, and can not be high or low. The left middle finger, ring finger and little finger hold the cotton tightly, the tip of the thumb and the index finger are closed, the middle is oval, the area should not be too large, and the fiber shows the thumb and The index finger is about 1.5 cm. At this time, the right hand starts to pull the first fiber. The range of the hand grip fiber is 5-6 mm. It is required to grab the fiber and not let it slip. The number of times the first cotton fiber is drawn is generally 13-15 times, each time the fiber extracted is thin, and then the left hand sorts and twists the fiber on the right hand. When pulling the second hand, the left hand and right hand have taken the fiber and grabbed it at 3-4 mm, and extracted 10-12 At this time, the fibers in the right hand are then sorted and twisted in the left hand. When pulling the third fiber, use the right hand to grasp the second fiber that has been extracted from the left hand at 2-3 mm, and then extract it for 3-5 times. Finally, the left hand reorganizes and shapes the fiber on the right hand to complete. Put the towed cotton bundle on the fleece board and use the steel ruler to measure in the middle of the fiber along the fiber direction. The ruler head is aligned with the upper end of the fiber and the lower end is aligned with the scale of the steel ruler to complete the entire length inspection process.

3. Basic requirements for hand pull length

The standard of hand pull length is the requirement for measuring the third formed cotton bundle, which is generally judged by six words, namely flat, straight, even, clean, fast and accurate. The so-called flat is that the upper and lower sides of the cotton bundle should be flat and parallel, and cannot be inclined, and the left and right sides should be symmetrical. Straight, that is, the fiber should be straightened, not bent. Uniform means that the fibers are arranged neatly and not in disorder. Clean, it is required that the cotton bundle is clean, and no obvious impurities, such as leaf debris, wire, cotton lumps, etc., can be seen. Flat, straight, flush, and clean refer to the quality requirements of the length of the hands.

Fast refers to the proficiency of hand-pulling the length, and the speed should be fast to meet the requirements of the cotton acquisition and inspection. Accuracy is the core. It requires that the length of the cotton bundle can be correctly determined by measuring the length. If the length of the hand is not accurate, it will lose the meaning of length inspection. Even if the cotton bundle is pulled beautifully, it is meaningless.

Second, hand-pull length technology and skills

To master the basic skills of cotton fiber length, it is not enough to be familiar with and understand the basic movements of hand-pulling length and general operating specifications, but also need to master certain hand-pulling techniques and skills, which is the key to improving the hand-pulling ruler technique.

1. Sampling techniques and techniques

There are two concepts of cotton length sampling: one is to take a small sample from the whole batch of large samples; the other is to take a length sample from the small sample, generally about 15 grams, which requires arbitrary sampling. Do not choose very good or poor cotton The representative cotton fiber is representative. Judging from the actual situation, hand-pulled sampling generally adopts fixed-point extraction of fibers, and the test results are more accurate. When multiple points of up, down, left, and right are drawn, the fibers tend to be longer, affecting the accuracy. The so-called representativeness means that the long fiber, the normal fiber (main body fiber), and the short fiber must be taken in the hand, and the length is shortened by three times. The third fiber is generally drawn 3 to 5 times, which is the length of the main body. The fiber is more accurate, the length of the main body is the length to be checked, and it is one of the basis for cotton price.

2. Fiber extraction technology and skills

When the fiber is drawn, the finger pressure should be consistent, and the extracted fiber can be uniform in thickness. If the finger pressure is light or heavy, some fibers will be drawn, and some fibers cannot be drawn, and the fibers cannot be uniform. During the extraction process, it is necessary to remove impurities at any time, and use the middle finger and the muscles of the lower end of the thumb to remove the messy fibers and impurities and keep them clean. The extracted fibers are like carding, and the overlapping of fibers should be clear and clear at a glance.

3. Fiber selection technology and skills

Throughout the process of hand-pulling, the fibers are traded for three times, to lengthen and short, and the purpose is to obtain the main fiber. Practice has proved that if more long fibers are obtained, the result is a longer length; if more short fibers are obtained, the length is shorter; short fibers If you cut more, the length is longer; if you cut more long fibers, the length is shorter. Long and short lengths, trade-offs are the main reason. Only with standard length samples and repeated practice of fiber trade-off techniques can we meet the quasi requirements.

4. Fiber twisting technology and techniques

The basic action of twisting is summarized in three words: "pinch, knead, wipe". The purpose of pinching is to gather the fibers into a whole; the purpose of kneading is to make the thickness of the fibers uniform, and the width of the fibers on the handle is controlled to about two centimeters; the purpose of wiping is to make the fibers straight. In terms of technique, the pinching force should be heavy, the kneading force should be light, and the wiping force should be lighter. The twisting action is required to pinch, knead, wipe once in place to avoid repeated twisting and cleaning of the fiber, which will make the cotton fiber on the hand less and less, and finally the length of the cotton bundle cannot be shaped.

5. Cotton bundle modeling technology and skills

The shape of the length cotton bundle is required to be beautiful, generous and accurate. When pulling the third bunch of cotton, you must complete the styling work. Straighten the left and right sides of the bunch of cotton gently to make the lines clear and maintain the outline. The upper side should be straight and the upper end of the cotton bundle is natural Open, generally 5-6 mm, the root of the cotton bundle should be straight, and the fibers overlap into a straight line, which cannot be misaligned, which is convenient for measuring. The shape of the cotton bundle is mostly a rectangle or a fan shape. The rectangle requires four sides to be parallel, the fan shape requires parallel up and down, and left and right symmetry. These two shapes can be selected by yourself. After pulling the third one, press the right thumb firmly to press the fiber to the first position of the index finger. The thumb moves away from the index finger to the upper right along the direction of the fiber. The index finger bends in a "7" shape, and the cotton fiber is placed on the fleece. On the top, first put the velvet board, then the index finger will gently leave the fiber root against the velvet board, and the position of the cotton bundle cannot be moved before the length can be determined by measuring.

3. Notes on the length of hand pulling

1. Length relationship of different types of cotton

Seed cotton, top roller cotton and sawtooth cotton are different length inspection items, and the method of hand pulling is roughly the same. If the same hand pulling method is used, the length results are slightly different: Generally, the fiber length of seed cotton is directly drawn from the cotton seed, and the strength of hand pulling Large, easy to straight fibers, less impurities, good hand feel, slightly longer than the top roller cotton; the top roller cotton processed by the top roller has more impurities, smooth fibers, stronger hand pull, and slightly longer length than sawtooth cotton; The cotton processed by the sawtooth machine has a lot of neps and wires, which is difficult to clean, the hand pull is less, the fibers are naturally bent and heavier, and the length is slightly shorter than the top roller cotton. Seed cotton and top roller cotton, top roller cotton and zigzag cotton are generally about one millimeter in length. In order to accurately check the length, there are differences in techniques and techniques. On the one hand, in the twisting strength, the seed cotton should be light, the top roller cotton is heavier, and the sawtooth cotton is the heaviest. On the other hand, in the selection of fibers, it should be noted that the longer fibers of the seed cotton should be cut more, and the shorter fibers should be cut less. The top roller cotton is basically pulled in the normal way. Sawtooth cotton should have less long fibers and short fibers more, so as to narrow the length gap of different types of cotton and achieve the purpose of accurate inspection. According to the inspection regulations, if the difference between the length of seed cotton and lint is found, the length of lint inspection shall prevail.

2. Length relationship of cotton with too much water content or too small

If the water content of the cotton is too large, the fiber will naturally bend less when it exceeds 10%. It is easy to pull straight and the length is long when you pull it. When you pull it, you should pay less attention to it. The result is easy and accurate. If the water content is too small, and the cotton moisture content is less than 8%, the fiber will naturally bend severely. It is not easy to pull the fiber straight when the hand is pulled, and the length is easy to be short. Pay attention to increase the twisting force when pulling the hand, and the longer fiber should be less. Only in this way can the length result be accurate.

3. The changing law of fiber length in different periods

Due to the different growth environment of cotton in different periods and the external natural conditions, it has a direct impact on the elongation and thickening period of the fiber, and the length of the fiber is different. Taking upland cotton as an example, the fibers of early cotton are mature and thicker, generally 28-29 mm in length. Medium-term cotton fiber is the best mature, medium-thick fiber, generally 30-31 mm in length. Late cotton has poor maturity and fine fibers, generally 23-27 mm in length. In the actual inspection work, it is very helpful to grasp the changing law of cotton fiber quality in different periods in time to guide the inspection work correctly.

4. Differences of different cotton fibers

Judging from the type inspection, the types of cotton are different, and the fiber lengths are also very different. Generally, the sea island cotton (long-staple cotton) has fine fibers with a length of more than 37 mm and a maximum length of 45-46 mm. Cashmere) fibers are finer, with a length of 27-31 mm. The fibers of medium cotton and grass cotton (thick velvet cotton) are thick and short, and the general length is about 20-23 mm. During the inspection, the cotton types should be correctly distinguished, and the length range of different cotton types should be mastered.

5. The relationship between length and regularity

Because the position of cotton peach on the cotton plant is different from that of the fiber on the cotton seed, the fiber maturity is good or bad, and the fiber length is long or short. From the analysis of the distribution of fibers on the cotton seed, the fiber in the middle of the cotton seed is longer, the fiber at the two ends of the cotton seed is shorter, and it is smoothed out, just like a finger straightened by a person, the middle is long, and the sides are short. Problem, the concept of fiber uniformity is relatively easy to understand. The so-called uniformity refers to the difference between the length and shortness of the cotton fiber of the same variety is called the uniformity. The smaller the gap between the long fiber and the short fiber, the better the uniformity, and the greater the gap, the worse the uniformity. For good cotton, the length of the hand pull is easy to be accurate, and the cotton with poor uniformity is easy to be longer or shorter. Therefore, for cotton with poor uniformity, the longer fibers should be given a little more, and the shorter fibers should not be given too much to prevent deviations in the length.

6. Compare the length of the hand with the instrument

The measurement of cotton length by instruments should be more advanced, scientific and accurate. There are technical problems and technical and technical problems in the length of hand pulling, which is easy to change from one to the other, and is not easy to be accurate. However, because the length of the hands is less time-consuming and fast, it is suitable for the needs of mass acquisition and inspection. Therefore, in the inspection, the method of combining the length of the hand with the measurement of the instrument is used to take advantage of the shortcomings, and often make comparisons to guide the acquisition inspection to achieve the purpose of correct inspection. If there is a deviation between the length of the hand and the measured length of the instrument, the measurement result of the instrument shall prevail.