In recent years, four-roller negative pressure compact spinning has developed rapidly, and some domestic companies that originally produced three-roller negative pressure compact spinning have also begun to develop four-roller compact spinning. The principles of the two negative pressure compact spinning methods are different, and each has its own suitable process. Spinning enterprises will also choose the appropriate method according to their own conditions.
The principle determines the difference between the two
The three-roller compact spinning has a better effect of absorbing hairiness because it is different from the four-roller type. Determined by the structural form of the aggregation device.
Although both negative pressure slots are inclined to the yarn output direction, the three-roller negative pressure compact spinning gathering area extends from the front roller nip to the twisting nip. , achieving full-process aggregation; while four-roller negative pressure compact spinning only extends from the front roller nip to the end of the negative pressure slot, and there is no aggregation in the small distance between the end of the negative pressure slot and the twist-stop nip. Therefore, relatively speaking, the three-roller negative pressure gathering stroke and gathering time are longer, the gathering effect is better, and the hairiness is relatively less.
Comparing the transmission modes of the two gathering devices, it can be seen that the four-roller negative pressure compact spinning gathering roller is actively driven by the toothed front roller through the bridge gear to the toothed small roller. The gathering top roller must press against the small roller, so the gathering stroke cannot extend to its nip line. If the position is too far back, the top roller will not rotate or will not rotate smoothly. If the mainstream SKF spring weighting arm is used, the forward impulse of the top roller in front of the weighting arm must be increased to about 3 mm, and cannot be too small or too large. Three-roller negative pressure compact spinning is a gathering top roller that is passively driven by the front roller through a bridge gear. The gathering top roller can be directly pressed to the end of the negative pressure slot, so the gathering effect can be extended from the front roller nip to the twisting nip. .
The fibers entrained in the three-roller “transmission pair” act as a “solid lubricant” and increase slippage. As the yarn becomes thicker, this slippage becomes more severe, so there must be an adjustment amount called “gathering draft”. The four-roller type does not have this “solid lubricant” effect, and does not need “aggregated drafting”, which should be said to be an advantage. However, there is still slippage after all, so in the mechanism design, the linear speed of the fourth roller must be slightly greater than the linear speed of the front roller, but it is not adjustable, so most users think that it does not have “aggregated drafting”.
However, if medium and coarse count yarns are spun and the thickness of the slivers increases, the positive pressure that should be distributed across the width of the pressure roller becomes concentrated on the middle sliver position, and the transmission conditions deteriorate. , in fact, it also needs to be adjusted, but the mechanism design does not give the user room for adjustment, and the advantages turn into disadvantages.
The three-roller type net hoop is placed on the negative pressure pipe, and the outlet end of the gathering groove can be as close as possible to the pressure roller jaw; while the four-roller type net hoop is placed on the roller, and the negative pressure pipe is The position of the gathering groove of the pressure tube is limited by the roller, and the “uncontrolled” distance between the whiskers must be larger, which seems to be detrimental to spinning high-count yarns. Three-roller spinning of high-count yarn is more advantageous because the amount of wadding fiber is small, the “solid lubrication” effect is not obvious, and the mesh ring transmission is relatively stable. Spinning medium and low-count yarns can be adjusted with the so-called “gathering draft”, which expands the scope of use, although the effect is not ideal.
The performance of four-roller compact spinning for high-count yarns is not as good as that of three-roller spinning. However, because there is no “solid lubricant” factor, within the general yarn count range, it The use and maintenance are low, and there is no requirement for frequent grinding of the roller. It is recommended that textile machinery enterprises can subdivide the design into several grades according to the yarn count in terms of the gear transmission speed ratio of the mesh ring to expand the scope of use.
Three-roller will not be eliminated
In the short term, three-roller compact spinning will not be eliminated by four-roller. There will be a certain market.
However, four-roller compact spinning has many advantages over three-roller compact spinning in terms of roller maintenance and use. For example, the drafting and gathering top rollers of three-roller compact spinning cannot be used universally, nor can they be used in common with ordinary ring spinning top roller cores. When polishing the top rollers, you need to disassemble the top roller box and polish a pair of top rollers simultaneously, and press Grind the outer diameter to a certain proportion and keep its transmission ratio unchanged.
In the four-roller compact spinning, the toothed front roller drives the toothed small roller through the bridge gear and then drives the compact spinning resistance twist top roller, which avoids complicated operations, but due to replacement The toothed front roller requires higher initial equipment investment, and the three-roller compact spinning has better hairiness absorption effect.
From the perspective of grid ring transmission principle and structure, we can understand that compared with three-roller compact spinning and four-roller compact spinning, it is better in spinning medium and high counts. When spinning yarn, the three-roller compact spinning has better yarn-forming effect. When spinning medium and low-count yarn, the yarn-forming effect of three-roller and four-roller compact spinning is similar.
Enterprises must make scientific evaluations
Many people now think that three-roller compact spinning is outdated and backward, and four-roller compact spinning technology Advanced viewpoints. I think this is over-promotion and publicity by some corporate marketers. What is the difference between three-roller and four-roller compact spinning? From the perspective of investment cost, the three-roller compact spinning does not need to replace rollers and roller blocks, and its investment cost will definitely be lower than that of the four-roller type.
From the quality level, in terms of evenness, because no new rollers have been replaced, the three-roller compact spinning and the four-roller spinningThe evenness difference is about 0.2, but there are some companies where the evenness level of three-roller compact spinning is better than that of four-roller type. This depends on the level of installation and maintenance. Generally speaking, a gap of 0.2 to 0.3 is normal. ; In terms of hairiness, the hairiness index of three-roller compact spinning is about 0.3 to 1.0 better than that of four-roller spinning; in terms of strength, both sides are almost the same, and both sides have their own advantages in terms of details and neps.
From the perspective of maintenance intensity, because the four-roller compact spinning system has more parts and more transmission parts than the three-roller type, the maintenance work of the four-roller compact spinning system is It is very hard; the cots of three-roller compact spinning need to be ground in pairs, so the working pressure of the top roller room will increase a lot.
From the perspective of consumption cost, the four-roller type has bearings, bridge gears, mesh rings, etc., and the three-roller type has top rollers, bridge pinions, mesh rings, etc. Consumption, running for 2 to 3 years. Comparatively, when spinning yarns with 6 to 16 counts and below, the consumption of both sides is almost the same, and the four-roller compact spinning method has a slight advantage; when spinning yarns with 21 to 200 counts, the three-roller type The advantages of compact spinning are obvious.
From a long-term perspective, three-roller compact spinning has fewer parts, simple structure, low investment cost, and easy maintenance, and the spinning quality is no better than that of four-roller compact spinning. Difference. Therefore, three-roller compact spinning and four-roller compact spinning each have their own advantages and disadvantages. If you are spinning yarn with more than 16 counts, I will definitely choose the three-roller compact spinning system. </p