Journal of Textile Research ›› 2019, Vol. 40 ›› Issue (12): 127-133.doi: 10.13475/j.fzxb.20181203707

• Machinery & Accessories • Previous Articles     Next Articles

Modeling of rotary shifting motion characteristics of electronic dobby and influence thereof on shedding mechanisms driving

YUAN Ruwang1,2(), ZHU Leilei1,2, LÜ Xuekui3, YANG Jiamin3   

  1. 1. School of Mechanical Engineering, Tiangong University, Tianjin 300387, China
    2. Tianjin Key Laboratory of Advanced Mechatronics Equipment Technology, Tiangong University, Tianjin 300387, China
    3. Jiangsu Jinlong Technology Co., Ltd., Suzhou, Jiangsu 215500, China
  • Received:2018-12-17 Revised:2019-08-13 Online:2019-12-15 Published:2019-12-18

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Abstract:

In order to address the adaptability of electronic dobby shedding to different weaving technologies, the construction and motion characteristics of the rotary shifting mechanism were analyzed. Methods for kinetically analyzing and designing the mechanism based on the fixed cam-slider combination were proposed, and a rotary shifting density sinusoidal motion curve model and a relative motion transmission model were established to facilitate the serialized design of the products. Then the influence of the changes in the linkage parameters on the performance of the rotary shifting mechanism and the workmanship of the shedding was investigated. The results show that the relative motion between the rotator arm and the eccentric link can be approximated as the constant angular speed ratio transmission, where the jacklever's motion eigenvalue starts from 0.000 and changes continuously along with the density adjustment coefficient without abrupt changes. The cam contour, pressure angle, curvature radius, the motion eigenvalue of the jacklever and its time of relative stillness to the main shaft are all reduced. A proper selection of the density adjustment coefficient can facilitate achieving an optimal pattern of the changing acceleration speed or torque to meet the needs of different weaving technologies, thereby laying a theoretical groundwork and providing a technical reference to the serialized design of electronic dobby.

Key words: electronic dobby machine, rotary shifting motion characteristic, shedding mechanism, density sinusoidal motion curve

CLC Number: 

  • TS1031

Fig.1

Working principle of rotary shifting mechanism"

Fig.2

Rotary shifting mechanism motion model"

Fig.3

Angular displacement relationship around parallel axis. (a) Traction angle displacement; (b) Relative angular displacement; (c) Absolute angular displacement"

Tab.1

Parameters of rotary dobby mechanism"

l1/mm l2/mm l'4/mm l5/mm l6/mm ψ/rad
116.000 57.717 20.000 165.000 95.000 1.903 2
φ10/rad φ20/rad φ40/rad ∠EOC'/rad X/mm Y/mm
π/2 3.760 8 π/2 0.724 5 185.100 39.850

Fig.4

Eccentric link relative movement characteristics with different rotation angle and different b values. (a)Relative angular displacement; (b) Relative analogous angular velocity; (c) Relative analogous angular acceleration; (d) Relative analogous angular jerk"

Fig.5

Eccentric link absolute motion characteristics with different rotation angle and different b values. (a) Absolute angular displacement; (b) Absolute analogous angular velocity"

Tab.2

Eigenvalues of eccentric link with different b values"

b Vm Am Tm
0.000 2.000 0 6.283 2 8.162 2
0.134 1.763 7 5.888 0 5.772 4
0.410 1.418 4 7.384 0 4.194 7
0.500 1.333 3 8.753 4 4.299 3

Fig.6

Comparison of experimental and fitting data of eccentric link. (a) Angular displacement; (b) Analogous angular velocity; (c) Analogous angular acceleration"

Fig.7

Transmission analysis of eccentric link with different l4 values"

Tab.3

Transmission ratio analysis with different l4 values"

l4/mm λmax λmin Δλ=λmax-λmin |λmax-1| |λmin-1|
56 0.933 0.740 0.193 0.067 0.260
58 1.000 0.779 0.221 0.00 0.221
60 1.071 0.819 0.252 0.071 0.181

Fig.8

Cam actual profile with different b values"

Tab.4

Cam parameters with different b values"

b值 最大极
径/mm		 最大压
力角/(°)		 最小曲率
半径/mm
0.000 88.244 45.24 27.942
0.134 86.143 40.56 25.227
0.410 80.578 30.55 14.801

Fig.9

Jacklever motion characteristics with different rotation angle. (a) Angular displacement; (b) Analogous angular velocity; (c) Analogous angular acceleration; (d) Analogous angular jerk"

Tab.5

Jacklever suspension period with different b values"

阈值m 角位移/
(°)		 相对织机主轴静止转角/(°)
0.000 0.134 0.410
1.000 24.06 154 142 112
0.990 23.78 176 164 132
0.975 23.49 192 188 148
0.950 22.86 204 202 162
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