Judgement of Card Clothing Failure
Card cloths for carding machines are respectively installed on the pre-carding rack cover, lick-in roller, fixed cover, cylinder, doffer, and rotary cover. Their sharpness directly determines the quality of the card sliver. The cotton mill’s judgment on the card clothing failure problem comes down to the sharpness and surface roughness of the card clothing.
Feel the sharpness of the card cloth with your hands and divide it into 5 levels: the needle teeth are sharp and feel sticky and tingling, which is the top grade card cloth; the needle teeth are sharp and have a tingling feeling, which is the medium and high grade needle cloth. Cloth; the needle teeth are sharp and have a prickly feel, which is a medium card clothing; the card clothing is slightly sharp and has a sense of forward and reverse directions, which is a medium and low-grade card clothing; the card clothing is slippery and has no sense of forward and reverse directions, which is a low-grade card clothing. To evaluate the sharpness of the card clothing, the entire width of the cylinder, doffer, flat plate and licker-in shall be considered.
Judging the quality of card clothing through the senses is the most direct method, and you can quickly know the condition of the card clothing. In production, the sharpness and surface roughness of the card clothing on the carding machine have been judged by the senses to be medium to low. However, because the cylindricity of the card clothing tooth tips on the entire machine is quite good, the correction of the gauge is quite standard and ensures It ensures the consistency of the left, middle and right spacing during machine production, meets the process requirements, and the indicators are relatively stable. Although some carding machines have replaced the card clothing due to unstable sharpness and surface roughness indicators of the card clothing, the product indicators have declined after the replacement, which has made it difficult to maintain the card. It not only wastes manpower and material resources, but also reduces the cost of maintenance. Workers’ enthusiasm for work and loss of confidence in work. The author believes that judging the sharpness and surface roughness of the card clothing through the senses to determine whether the card clothing has failed cannot meet the needs of production management.
Causes of Card Clothing Failure
The low precision of manufacturing equipment is the main reason for the failure of card clothing. With the continuous improvement of equipment manufacturing processes and the widespread application of new materials, aluminum alloy rotary cover plates, fixed cover plate frames, and drum barrels have been put on the market as mainstream products, but there are still many problems. Only by selecting appropriate materials and improving the manufacturing accuracy of equipment can we effectively prevent card clothing failure. At the same time, we must also take into account the construction of the technical talent echelon to achieve an effective combination of quality and cost of use.
The manufacturing accuracy of the cover frame is low
The cover frame is divided into two types: cast iron and aluminum alloy. Although the material quality is excellent, during the coating process, due to process differences or different equipment conditions, the flatness of the bottom surface of the cover frame becomes worse. Measuring its left and right deviations can even Up to 0.51 mm; some well-known manufacturers promise to control the deviation to the standard value of 0.08 mm, but they still cannot guarantee the flatness of the coated card clothing and the accuracy required by the machine process.
Insufficient tensile strength of the cover chain
The mainstream cover chain products on the market include steel, aluminum alloy, etc. The user requires the flat chain to have a long service life and high tensile strength to avoid deformation, breakage, wear and other problems caused by the connection between flat card clothing and cylinder card clothing, which reduces product quality and increases production costs.
Low cylindricity of the cylinder or low flatness of the bottom of the cover
The cylindricity of the cylinder, doffer and licker-in determines the cylindricity of the covered card clothing. The requirements for the cylindricity of the cylinder and the flatness of the bottom surface of the cover plate are 0.02 mm. After wrapping the card clothing It is required to reach 0.03 mm. When the manufacturing accuracy of the manufacturer cannot meet this requirement, the use requirements of wrapped card clothing cannot be guaranteed.
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