The rotation process of the circular knitting machine is essentially a movement primarily consisting of a circular motion around a central axis, with most components being installed and operating around the same center. After a certain period of operation in the weaving mill, the machinery requires a comprehensive overhaul. The main work during this process involves not only cleaning the machines but also replacing any damaged parts. The primary focus is on inspecting the installation accuracy and operational precision of each component to determine if there have been any changes or deviations beyond the specified tolerance range. If so, corrective measures must be taken.
An analysis is presented on the causes that lead to the failure in achieving the required range of circularity and flatness in components such as syringes and plates.
The rotation of the pulley failed to meet the required precision.
For instance, the wear of the locating grooves between the plate and the pulley (more common in a frictional sliding mode), which can lead to looseness or wear of the wire guide track or the center sleeve within the double-sided machine's great bowl, can all result in the inability to achieve the required precision for the cylinder's circularity. The inspection method is as follows: place the machine in a stationary state, place the dial gauge's pointer on a point of the toothed disc holder (if the screws securing the needle or the disc to the toothed disc holder or the needle drum have not been loosened, the pointer can also be placed on a point of the needle cylinder or the disc), with the dial gauge seat adsorption on a machine that does not rotate with the toothed disc or the needle drum, such as a large bowl or pot, as shown in Figure 1 and Figure 2. With forceful manipulation of the chuck or pin plate tray, observe the change in the dial gauge pointer range. If it falls below 0.001 mm, it indicates that the chuck's operating accuracy is excellent. When it ranges between 0.01 mm and 0.03 mm, the precision is good; when it exceeds 0.03 mm but is less than 0.05 mm, the precision is average; and when it exceeds 0.05 mm, the chuck's operating accuracy becomes suboptimal. At this point, adjusting the circularity of the pin plate to within 0.05 mm would be extremely difficult or even impossible, necessitating the restoration of the chuck's or tray's operating accuracy first. The method for restoring precision in operation shall vary depending on the different structures and modes of rotation of the pulley, which is beyond the scope of this article.
When the contact surfaces between the twelve cogs and the piston cylindrical are uneven or when the contact surface between the pin plate and the base is uneven, upon application of the circumferential tension wire, the gaps between the piston cylindrical , the pin plate, the disc, and the base will be forcefully pressed together, causing the piston cylindrical and the pin plate to undergo elastic deformation. As a result, the roundness will deviate from the required tolerance. In practical terms, when the retaining screws are loosened slowly, the circularity of the chuck and spindle can easily be adjusted to within 0.05mm, but upon checking the circularity again after locking the screws, it exceeds the requirement range of less than 0.05mm by a significant margin. The steps for tackling this issue are as follows
Relax the tightened screws, adjust the syringe and needle plate roughly to a round shape, ensuring that it is less than 0.03 mm in diameter. Release the head of the gauge, place the gauge head on the rim or surface of the cylinder neck, or the needle plate, rotate each securing screw until the gauge pointer points downward, secure the screws, observe the change in the gauge needle, if the reading decreases, it indicates that there is aninterval between the cylinder, the needle plate, the gear wheel or the base.
As the pointer on the gauge changes, insert appropriate thickness spacers between the tightening screws on either side, lock the screws again, and observe the change in the pointer until it is adjusted to a change less than 0.01 mm after locking the screws. Ideally, there should be no change at all. Proceed to tighten the next screw in a consecutive manner, repeating the process until each fastening bolt exhibits a change in the pointer of less than 0.01 mm after being tightened. This ensures that there is no gap between the syringe, needle plate, and the gear or support base where the screws are tightened. It is noteworthy that after each screw position has been adjusted, before proceeding to the next screw, it should be loosened to ensure that the syringe and needle plate remain in a relaxed state throughout the adjustment process. Inspect the flatness of the syringe and needle plate; if the pointer changes by more than 0.05 mm, insert shims to adjust it to within ±0.05 mm.
Loosen the self-tapping tap head and position it on the side of the syringe or at the rim of the chuck. Adjust the circularity change of the syringe plate by no more than 0.05 mm and lock the screws.
The precision of the sinker,cam base plate or shuttle frame cannot meet the standards. Such a type of machine part is usually a carrier for the cam base, whose flatness and return angle requirements are not as high as those of the needle plate or the needle cylinder. However, due to their adjustment during production in response to changes in the product, they will adjust up and down or left and right, rather than like the needle plate or needle cylinder, which can be adjusted once and then remain unchanged unless replaced. Therefore, during adjustment, the installation and tuning of these blocks become crucial. Below, we will introduce the specific method through the example of the Life-Killing Board, 2.1 Adjusting the Balance
When the tray's level is out of tolerance, first loosen the screws and positioning blocks on the tray racks, and adsorption scales seated on syringes,position the pointer head on the tray's edge, rotate the machine to a particular tray, and secure the bolts that fasten the tray to the tray crame. Observe the changes in the pointer. If there is any change, it indicates that there is a gap between the bracket and the tray, which requires the use of shims to secure it. When the locking screw is tightened, the variation in measurement is only 0.01 mm, but it is particularly noteworthy that due to the larger contact surface between the bracket and the tray, as well as the fact that the pointer's direction does not align with the same radius as the table head, when the locking screw is tightened, even though there is a gap, the change in the pointer's reading may not always be a decrease, but could also be an increase. The size of the pointer's movement directly reflects the position of the gap between the bracket and the tray, as shown in figure 3a, where the dial gauge would read a larger value for the locking screw. Should the foot be in the position depicted in Figure 3b, the reading on the tachometer for the locking screw would decrease. By discerning the variations in readings, one can determine the position of the gap and apply suitable measures accordingly.
Adjustment of the roundness and flatness of the double jersey machine
When the diameter and flatness of the double jersey machine exceed normal ranges, adjustments must first be made to ensure that the bearings and pulleys within the main cylinder are not loose or have a looseness within acceptable limits. Once this is confirmed, adjustments can proceed accordingly. In harmony with the level
Install the self-contained unit according to the instructions provided, and loosen all the large bolts that secure it. Transferring the pivot plate to a central support foot, tighten each screw securely, observe the change in the dial gauge to ascertain whether there is any gap between the central support foot and the great tripod, and if so, its precise location. The principle is akin to that employed in analyzing the change in the dial reading when adjusting the level of a tray, where gaps are filled with spacers. After each adjustment of a screw position, relax this screw before proceeding with the next screw's adjustment until each screw's tightening causes a change in the watch's reading of less than 0.01 millimeters. Having completed this task, rotate the machine as a whole to check if the level is within normal parameters. If it exceeds the normal range, adjust with shims.
After adjusting for concentricity, the micrometer shall be installed as per requirement. Inspecting the roundness of the machinery to determine if it falls outside of normal parameters, adjustments can then be made via the machine's adjustment screws to bring it back within range. It is essential to pay attention to the use of screws, just as with the use of locating blocks for the tray. One should not forcefully push the center sleeve into place by means of the screws, as this would cause elastic deformation of the machinery. Instead, utilize the adjustment screws to move the center sleeve to its desired position, then release the screws and read the measurement on the gauge. After adjusting, the locking screws should also adhere to the center sleeve’s surface, but no force should be exerted upon it. In summary, no internal stresses should be generated after the adjustment is completed.
In adjusting concentricity, it is also possible to select six diagonal points as reference points, for some machines exhibit eccentric motion due to wear, causing their trajectories to resemble an ellipse rather than a perfect circle. As long as the difference in readings taken diagonally falls within the acceptable range, it can be deemed as meeting the standard. But when the rim is distorted due to the plate's deformation, causing its movement path to resemble an ellipse, it must first have the plate’s reshaped to eliminate the distortion, thus restoring the rim's movement path to a circular shape. Similarly, an abrupt deviation from normalcy in a particular point can also be inferred as resulting from either wear or deformation of the pulley. If it is due to the deformation of the plate’s, the deformation should be eliminated; if it is due to the wear, it would require repair or replacement depending on the severity.
Post time: Jun-27-2024