In the actual production process, textile enterprises will inevitably encounter problems due to large batches The product is downgraded or downgraded due to uneven yarn dryness. This kind of large-scale defective products is often caused by the failure of the mechanical equipment itself. In this case, regular mechanical waves will often appear when using modern testing equipment. The reasons for the formation of mechanical waves are very complex, involving many mechanisms, parts, and locations. To quickly and accurately judge special and difficult mechanical waves, in addition to being good at accumulating experience, such as being familiar with common mechanical wavelengths, waveforms, and unevenness curve shapes, It is also necessary to master the analysis methods of special mechanical waves such as hidden waves, harmonics, false waves and periodic waves through practice. How to reduce defective products caused by mechanical failure? Look down.
Using the self-networking Q-DATA channel
Currently Many textile companies have adopted automatic winding equipment, using the powerful functions of automatic winding and electric clearing to serve cotton yarn quality control. Now our company has opened the Q-DATA channel for all varieties with higher quality requirements, and cooperates with the self-winding alarm yarn to increase the control of product quality.
For example, a large batch of alarm bobbins were suddenly discovered on a certain automatic equipment of J18.2texK type in the post-spinning workshop, and the alarm bobbins were put back into the yarn. The yarn still could not be wound normally in the library and was thrown out again. The alarming bobbin was sent to the laboratory to test the weight. No obvious abnormalities were found after weighing for 100m. The bobbin was further tested for Uster evenness. No obvious mechanical waves were found in the 1-minute spectrogram of the first test. Therefore, the test length was increased, the test time was changed from 1 min to 2 min, and the sample length was increased from 400m to 800m. It was found that there was an obvious mechanical wave at 50m.
In response to the above situation, we searched for the cause based on the spinning package number. When tracking in the spinning workshop, we found that some of the newly hung rovings on the roving frame of the spinning machine had poor appearance. The newly hung large roving was taken to the laboratory for evenness testing. On the roving evenness spectrum, obvious draft waves and mechanical waves appeared at about 2m. In addition, it was found that some abnormal rovings were easy to break on the spinning frame. We further searched for the roving frame number and spindle position marked on the roving frame and quickly found the drawing can after the roving frame. When testing the drawing can, it was found that there was an obvious drag around 20cm~30cm. Stretch wave. The draw frame number is further locked based on the draw frame number. It was found that the toothed belt at the end of the draw frame was poorly engaged. It was analyzed that the draw frame maintenance worker did not adjust the toothed belt properly when adjusting the quality of the draw frame and replacing the crown teeth. Fortunately, the supply for the roughening process was relatively loose at that time, and not much sliver was spun. A total of 2 rows of roving and more than 60 tubes of cooked sliver were recovered. Due to the good use of the Q-DATA channel in post-spinning, most of the abnormal yarns turned into alarm bobbins and were thrown out. In addition, some abnormal yarns were cut off, which did not have a major impact on the post-processing process.
Use the small defect group function of the electronic cleaner
The small defect group function of the Loeffi electronic cleaner is specifically designed to target continuous small defects The so-called chain yarn defects are additionally set. Such small defects are harmless defects.
Generally speaking, the size of small defect groups is much smaller than ordinary defects and is within the acceptable range. Even if there are sporadic or single defects, it will have almost no impact on the cloth surface effect. However, if it occurs continuously or in large numbers within a short distance, it will have a bad impact on the cloth surface. For example, chain-like defects such as obvious regular black slats, dense slub yarns, and more hairiness. In order to further improve the quality of cotton yarn and reduce customer complaints, we have launched the Loepfe electronic cleaning small defect group function on some varieties.
Although the small defect group function can better remove some chain defects, the ultimate goal is to eliminate hidden quality risks through defect tracking. For the alarm yarn generated by the photoelectric yarn clearer, in addition to the quality and USTER tests, it is also necessary to add hairiness or black slat dryness tests. Only in this way can the small defect group function of Loepfe clearing be better utilized.
Analyzing mechanical spectrum diagrams
Generally, textile companies can judge spinning equipment faults based on Uster Pop diagrams location of occurrence. For example, the mechanical waves and drafting waves at 10m to 40m in the spun yarn spectrum are basically generated in the drawing process, and are mostly defects in the front area. Mechanical waves and drafting waves at 1cm to 4cm are mostly caused by poor meshing of the spinning gears; chimney-like mechanical waves appear at 80cm to 40m in the roving spectrum, and the general equipment failure is the front and rear areas of the end draw or the end draw. Drafting defects in the front area of the strip, and occasionally drafting defects in the rear area of the roving frame, are roving frame defects at 4cm to 80cm, and are loose and worn defects of the roving frame gear and transmission gear bearings at 1cm to 4cm; Mechanical waves and drafting waves appear at 80cm to 4m on the draw frame spectrum, which are generally drafting defects in the front and rear areas of the second draw frame or the front area of the first draw frame. Mechanical waves and draft waves appear at 1cm to 4cm. The wave expansion is caused by poor meshing of the final draw frame gears and wear of the light and heavy tooth wheel supporting foot bearings.
The analysis and evaluation method of spectrograms must be appropriate. We must not rely on one spectrogram, but increase the number of experiments to improve the credibility of experimental analysis. If there are mechanical waves in every spectrum, it means there is a commonality and there is a mechanical defect. Under normal circumstances, the calculated wavelength is basically close to the actual wavelength, and the tolerance error range is ±15%. When doing Uster Bard Pop chart barrage sampling, if it is rainy weather, the sample should be sealed to avoid being exposed to damage.The influence of ambient temperature and humidity will affect the test results. At the same time, it is necessary to control the humidity of the drying room temperature, because most drying meters are capacitive, which are greatly affected by temperature and humidity and are prone to abnormal data. When multi-column mechanical waves appear in the spectrogram, the analysis should be based on the main wave, that is, the fundamental wave. The fundamental wave is generally to the right of the harmonics.
The roving causes torsional vibration of the middle roller due to tightness of the lower apron or quality reasons, which will also form mechanical waves, which are so-called hidden waves. Because the slice length when detected by the evenness meter is 8mm, and this hidden wave is shorter, it does not appear on the roving evenness, but it will appear after the fine yarn is drafted. The characteristic of this kind of mechanical wave is that -30% details are easy to appear on the automatic winding machine. The length of the details ranges from 150mm to 200mm, and they appear continuously on the same bobbin. The solution is to replace the lower rubber ring with better quality or wash the lower rubber ring frequently. If that doesn’t work, replace the middle roller. </p
