Method for producing raw cotton of machine-harvested long-staple cotton with modal length of greater than or equal to 35MM

A method for producing raw cotton of machine-harvested long-staple cotton with a modal length of greater than or equal to 35 mm, comprising the steps:

• S0, planting cotton, comprising:
• S01, preparation before machine harvesting:
• allowing the irrigation amount of last watering a cotton field to be smaller than or equal to 375 m3/hm2, and cleaning up or recovering cotton field sundries;
• and
• S02, defoliation and ripening:
• when a natural boll opening rate of the cotton field reaches 30-45%, spraying a defoliating agent and a ripening agent;
• S1, selecting machine-harvested seed cotton:
• selecting machine-harvested seed cotton having an impurity content of smaller than or equal to 15.8%, a foreign-fiber content of smaller than or equal to 1.3 g/t, and a moisture regain rate of smaller than or equal to 15%;
• S2, cleaning seed cotton, comprising:
• S21, carrying out heavy-impurity cleaning by using a heavy-impurity cleaning machine;
• S22, carrying out foreign fiber cleaning by adopting a composite foreign fiber cleaning machine that combines winding and wind cleaning, wherein the composite foreign fiber cleaning machine adopts a structure having two alternately running channels of winding rods;
• winding rods in each channel have a diameter of 85-95 mm and a length of 2.5-3.0 m, toothed nails with a length of 30-35 mm are designed on the surface of each winding rod, a mounting density of the toothed nails is that four toothed nails are mounted around one cycle of each winding rod, the toothed nails have an axial spacing of 90-110 mm, and the toothed nails are arranged in a staggered manner along a peripheral direction;
• the winding rods in each channel have a left-right spacing of 154-164 cm and an up-down spacing of 176-187 cm;
• and 3 to 5 plucker rollers with a diameter of 400-420 mm are designed below the winding rods, and spacing bar gratings with a spacing of 9.5-10.5 mm are arranged under the plucker rollers;
• and
• S23, carrying out 3-6 passes of cleaning on the seed cotton by alternately using an inclined seed cotton cleaning machine and a large-impurity seed cotton cleaning machine, wherein the inclined seed cotton cleaning machine comprises 6 toothed nail rollers slantingly arranged in a shell from top to bottom, each toothed nail roller has a diameter of 420-430 mm, a working linear speed of 8.96-9.32 m/s, and a rotating speed of 400 r/min, toothed nails mounted on each toothed nail roller have a length of 49-51 mm, each toothed nail is in a form of a slender cone without a cone tip, a semi-ellipsoid at the tip end of each toothed nail has a diameter of 9-10 mm, and a tangent plane at the rear end of each toothed nail has a maximum diameter of 13-14 mm;
• the inclined seed cotton cleaning machine further comprises spacing bar gratings with a spacing of 9.5-10.5 mm;
• and the large-impurity seed cotton cleaning machine comprises one large roller which is arranged in a shell and is provided with a rack, a cotton brushing device matched with the large roller, and one independent recovery device, wherein the large roller has a diameter of 860-900 mm;
• during operation, the large roller has a linear speed of 8.61-8.89 m/s and a rotating speed of 155-165 r/min, the cotton brushing device is made of carbon-steel spring wires with a diameter of 0.35-0.5 mm, and the cotton brushing device is equipped with 88-92 bundles of steel wires per meter in length, each bundle comprises 60 to 70 steel wires, and a spacing between the bundles is 10.5-11.5 mm;
• and U-shaped racks at an angle of 55-57° are mounted on the surface of the large roller, four racks are mounted per cycle, and the racks have a circumferential spacing of 29.5-30.5 mm;
• S3, ginning:
• ginning the cleaned seed cotton obtained from the step S2 by adopting a stamping-knife-type or hobbing-cutter-type roller gin so as to separate cotton seeds from raw cotton;
• and
• S4, finishing raw cotton, comprising:
• S41, by using a cotton dust collection cage, carrying out staple collection on the raw cotton obtained by ginning in the step S3 so as to obtain separated raw cotton;
• S42, carrying out at least one pass of cleaning and impurity removal on the separated raw cotton by an airflow cleaning machine, and carrying out 1-2 passes of cleaning by a ginned cotton carding machine;
• and
• S43, carrying out staple collection by using a cotton dust collection cage again, and carrying out packaging so as to obtain machine-harvested long-staple cotton with low mechanical damage to fibers.