Key technology research of bobbin change actuator suitable for multiple bobbin types
Objective In a traditional knitting workshop,bobbin changes are carried out manually.This highly repetitive and low automation production method makes it difficult and inefficient to change the top layer bobbins on the yarn frame.Although different sizes of cylindrical and conical bobbins are used with circular knitting machines,the bobbin clamping mechanisms are available only for specific sizes and types of bobbins,causing problems for bobbins with different inner diameters and tapers.Therefore,this research focuses on designs an bobbin change actuator for different types of bobbins to achieve automated circular weft knitting.Method According to the structural characteristics of the yarn frame and the process of bbbin replacement in the knitting machine,this paper designed a bobbin change actuator composed of a clamping mechanism,a brake mechanism,a clutch mechanism,a yarn pushing mechanism,a flip mechanism,and son on.The actuator was expected to adjust the contraction size of the clamping jaws and the angle between the jaws through the external expansion motor and the external expansion cylinder respectively,for different types of bobbin gripping.In order to solve the situation of symmetrical flare of the yarn frame bar,a flip mechanism was designed to drive the gripper mechanism for 180° rotation to achieve A/B bobbin replacement.After completing the design,the process of bobbin changing was simulated to verify the feasibility of the bobbin change actuator.In addition,in order to improve the operating life and stability of the bobbin change actuator,ANSYS Workbench software was used to simulate the exhaustive mechanics of the jaws with different diameters and lengths.Results The simulation results showed that when the length of the jaws was unchanged,the stress on the jaws was decreased with the increase of the diameter of the jaws,while when the diameter of the jaws was unchanged,the stress on the jaws was increased with the increase of the length of the jaws.According to the minimum inner diameter of the guide plate and the requirements of the gripping stability of the jaws,the diameter of the jaws was selected as 18 mm,and the length of the jaws is 58 mm.At this time,the deformation of the jaws is 0.1 mm,and the maximum equivalent stress was 29.7 MPa,which was smaller than the permissible stress of the 6060-T6 aluminum alloy,indicating satisfaction of the requirements for the yarn cylinder gripping with operation stability of the.After that,the experimental prototype was made and the gripping experiments of cylindrical and conical cylinders of different specifications were carried out.The experimental results showed that the gripper has a maximum external diameter of 65 mm and a maximum external taper of 15°,capable of gripping yarn tubes with three different sizes with good stability,among which the maximum mass of the gripped bobbin was 6 kg,and the minimum internal diameter of the gripped bobbin was 20 mm.Conclusion This paper analyzes the components and motion principles of each mechanism of the bobbin change actuator,carries out static simulation of the jaws of different diameters and lengths by using ANSYS Workbench software,and identified the optimal jaws diameter to be 18 mm and the jaws length 58 mm,meeting the design requirements.A prototype was developed,and the gripping experiments of cylindrical and conical cylinders of different specifications were carried out,and the experimental results proved that the bobbin change actuator is capable of gripping cylindrical bobbins and conical bobbins of different shapes and inner diameters.The automatic bobbin changes actuator introduced in this paper has been applied to a circular weft knitting production line in Guangdong,and it could be extended to textile production lines with wide application prospects.
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