关键词: 喷丝板, 不停丝, 自动化铲板, 一体化设计, 缓冲结构

Abstract:

Objective Board shoveling is an essential process in chemical fiber spinning production, in which the shovel blade is used to clean residual polymers from the spinneret surface. Automated board shoveling operation under stop-spinning condition was prone to causing pressure fluctuations in the extrusion pump which would affect the stability of spinning quality. Therefore, an automated shoveling system under non-stop-spinning condition was proposed with no negative influence on spinning quality. It could clean the spinneret surface and at the same time collect and discharge the flowing waste wires. However, the narrow space of spinning box greatly increased the difficulty of structural design of shoveling mechanism. In this paper, the structure layout design and detailed structural design were carried out to solve the structural design problem of the automated shoveling system above.
Method Referring to the design method of mechanical power distribution, a compact structure design scheme combining two functions of board shovel and wire discharge was proposed (Fig. 1), where the structure layout was in the form of the discharge assembly in the center and the shovel assembly on the side. A cantilever beam and series-parallel spring buffer technology was applied to the offset structure design of the shovel assembly, and the slip ring design technology was applied to solve the structural connection between the rotating wire collecting funnel and the stationary wire discharging pipeline in the wire discharge assembly. Numerical calculation methods, including mechanical modeling, finite element analysis, kinematic analysis, fluid mechanics, were applied to carry out the calculation and design of specific structural parameters of the two parts. Eventually, practical test methods were used to verify the correctness of the structural design through the development of the actual experimental device.
Results The linear motion performance of the shovel assembly was investigated in details through ANSYS simulation, where a contact force of 50 N was applied to the blade. The displacement difference of the cantilever structure at the three sets of guides supported by the spring K1 was within a few micrometer(Fig. 3). It was proved that the offset shovel assembly could move smoothly in line. Through further analysis of the contact stress distribution between the scraper blade and the spinneret surface, the scraper blade could be in full contact with the spinneret surface and keep pressed upon the surface. In order to avoid the rigid impact when the blade approached fast to be pressed on the spinneret surface, the mechanical modeling of the shovel setting movement was carried out, and the numerical calculation was performed to get the elastic coefficients of springs K1 and K2 in the buffer structure of the shovel assembly as 9 N/mm and 4 N/mm. Finally, through the development of the test device, the experiments of board shoveling and wire discharge were carried out under the laboratory simulation conditions. The actual shovel force in experiment was collected in real time to learn the influence of shovel force and shovel time on shovel effect. A more reasonable experimental result was shown in Fig. 11, during the spinneret surface was scraped with a preset force of 40 N, the actual shovel force converged gradually and stabilized after 2 s, and effective cleaning was completed within 5 s. Simultaneously, the functional experiments of wire discharge were carried out with the parameters of negative pressure and flow velocity obtained through Fluent fluid simulation. The simulated spinning objects flowing out of the spinneret could be all collected in the collecting funnel with a tendency to converge towards the center and then discharged downward(Fig. 12). Later the pipeline was opened to observe that no remains were hung on the wall inside the pipe.
Conclusion Through mechanical modeling, numerical calculation, simulation analysis and experimental research, the related analysis and calculation of the automated shoveling system with integrated structure have been done for the achievability of board shoveling and wire discharge, and the correctness of the structure layout and design were verified. Thus a new automated shoveling system under non-stop-spinning condition is provided for the spinneret cleaning without stopping the extrusion pump in the fiber spinning production, and the relevant design parameters are given to guide the development of the actual system design. That will be beneficial to ensure the stability of spinning quality.

Key words: spinneret, non-stop-spinning, automated board shoveling, integrated design, buffer mechanical structure