Journal of Textile Research ›› 2020, Vol. 41 ›› Issue (11): 150-155.doi: 10.13475/j.fzxb.20200301506

• Machinery & Accessories • Previous Articles     Next Articles

Method for testing natural frequency of weft knitting needles in free state

DAI Ning, PENG Laihu(), HU Xudong, CUI Ying, ZHONG Yaosen, WANG Yuefeng   

  1. Key Laboratory of Modern Textile Machinery & Technology of Zhejiang Province, Zhejiang Sci-Tech University,Hangzhou, Zhejiang 310018, China
  • Received:2020-03-06 Revised:2020-07-29 Online:2020-11-15 Published:2020-11-26
  • Contact: PENG Laihu E-mail:laihup@zstu.edu.cn

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Abstract:

The natural frequency characteristics of knitting needles on weft knitting machines are closely related to the property of weft knitting machines. The existing weft knitting machine knitting needles are small, slender, and have variable cross-sectional diameter in their free state, and the characteristics of the knitting needles at various stages are difficult to test. This research made use of a small and low-quality piezoelectric zirconate titanate ceramics (PZT) attached to the surface of the knitting needle to form an adhesive body structure. A high-performance impedance analyzer was used to perform a frequency sweep test on the bonded body. According to the complex impedance and phase angle curves at different frequencies, the modes of each order in the PZT free state were obtained. ANSYS finite element simulation software was used to compare and verify each mode of knitting needles and bonded bodies, and analysis was performed based on the cantilever curvature, deflection theory, and knitting needle vibration theory. The results of theoretical calculation and simulation test show that this experimental test method is able to measure effectively the natural frequency of the needles in the free state.

Key words: weft knitting machine, knitting needle, complex impedance curve, phase angle curve, ANSYS finite element simulation, vibration characteristic

CLC Number: 

  • TS103.7

Fig.1

Simplified diagram of knitting needle movement during loop forming process of weft knitting machine"

Fig.2

Schematic diagram of overall design of the natural frequency of the knitting needle"

Fig.3

Cross-section structure of bonded body"

Fig.4

Diagram of experimental connection"

Fig.5

Principle of measuring natural frequency of bonded body by impedance analyzer"

Fig.6

Graph of complex impedance-frequency and angle-frequency. (a) Group 1; (b) Group 2"

Fig.7

Schematic diagram of surface curvature of knitting needles during bending"

Tab.1

Statistical table of the first three order frequency of sample 1 and 2Hz"

试样编号 一阶频率 二阶频率 三阶频率
1 342.4 734.0 957.8
2 361.1 790.0 976.5

Fig.8

First 3 orders of modal analysis results of knitting needle. (a) Order 1; (b) Order 2; (c) Order 3"

Tab.2

Summary of knitting needle simulation and test results error result"

模态 仿真
频率/
Hz		 实验1 实验2
测试
频率/Hz		 测试
误差/%		 测试
频率/Hz		 测试
误差/%
1 383.1 342.4 10.6 361.1 5.7
2 896.7 734.0 18.1 790.0 11.9
3 1 019.0 957.8 6.0 976.5 4.2

Fig.9

First 3 orders of modal analysis results of bonded body. (a) Level 1; (b) Level 2; (c) Level 3"

Tab.3

Summary of bonded body simulation and test results error result"

模态 仿真
频率/
Hz		 实验1 实验2
测试
频率/Hz		 测试
误差/%		 测试
频率/Hz		 测试
误差/%
1 382.0 342.4 10.4 361.1 5.5
2 885.5 734.0 17.1 790.0 10.8
3 986.4 957.8 2.9 976.5 1.0
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