Simulation study on shape control of micro⁃fine universal direction spherical mechanical kinematic pair for in⁃mold micro assembly molding

doi:10.19491/j.issn.1001-9278.2023.01.011

Abstract

Abstract:

In general， the in⁃mold micro assembly molding of micro⁃fine universal direction spherical mechanical kinematic pair is difficult to meet the technical requirements of manufacturing dimensional tolerances. To address this common technical bottleneck， the technology of the functional self⁃lubricating liquid film⁃assisted in⁃mold micro assembly molding was proposed to realize its high⁃precision micro forming and assembly. The synergistic evolution law between the manufacturing diameter dimensional tolerances of spherical micro assembly interface and the slip coefficient of functional self⁃lubricating liquid film was simulated and studied. The results indicated that the diameter tolerance of the micro assembly interface had a positive correlation with the slip coefficient. The diameter tolerance also had a positive correlation with the near surface coupling temperature， the thickness of the continuous phase⁃transformation evolution zone， the thermal fluid structure coupling pressure， the elastic normal stress， and the viscous drag shear stress in the micro spherical assembly interface. When the slip coefficient decreased from 1×10⁹ to 1×10³， the diameter dimensional tolerance of the micro assembly interface decreased from 211 μm to 19 μm along with an improvement in the manufacturing accuracy by 91 %， and meanwhile its maximum coupling temperature decreased by 4.7 %. The maximum thickness of the continuous phase change zone decreased by 23.8 %， and its thermal⁃fluid⁃solid coupling pressure， elastic positive stress， and viscous drag shear stress decreased by 73 %， 72.8 %， and 56.3 %， respectively. This was attributed to the mechanism to realize the precision micro assembly of micro⁃fine universal direction spherical mechanical kinematic pair.

Key words: universal direction spherical mechanical kinematic pair, in?mold micro assembly molding, manufacturing acc?uracy, micro assembly, simulation

CLC Number:

TQ320.66

XUE Peng, ZHANG Yu, ZHOU Guofa. Simulation study on shape control of micro⁃fine universal direction spherical mechanical kinematic pair for in⁃mold micro assembly molding[J]. China Plastics, 2023, 37(1): 66-73.

Figures/Tables 18

Fig.1. Micro⁃fine universal direction spherical mechanical kinematic pair model

Fig.2. Flow chart of variable combination die and molding process

Fig.3. Finite element model

材料	$η$ / $P a ⋅ s$	$η r$	ξ	λ/s	β
PS	15 000	0.067	1.87	0.1	0.22

材料	$η$ / $P a ⋅ s$	$η r$	ξ	λ/s	β
PS	15 000	0.067	1.87	0.1	0.22

Tab.1. PTT model parameter of PS

Fig.4. Thermoviscoelastic plastic stress⁃strain relationship of PMMA

Fig.5. Effect of slip characteristics on interface coupling deformation morphology of micro assembly

Fig.6. Extraction path diagram of coupled deformation

Fig.7. Influence of slip coefficient on circular distribution of coupled deformation diameter tolerance

Fig.8. Manufacturing diameter dimensional tolerance vs. slip coefficient

滑移系数	热流固耦合变形最大尺寸偏差/μm	考虑成型收缩最大制造尺寸公差/μm	是否满足制造尺寸公差 ≤30 μm
$109$	226	211	否
$108$	124	109	否
$107$	84	69	否
$106$	58	43	否
$105$	44	29	是
$104$	38	23	是
$103$	34	19	是

滑移系数	热流固耦合变形最大尺寸偏差/μm	考虑成型收缩最大制造尺寸公差/μm	是否满足制造尺寸公差 ≤30 μm
$109$	226	211	否
$108$	124	109	否
$107$	84	69	否
$106$	58	43	否
$105$	44	29	是
$104$	38	23	是
$103$	34	19	是

Tab.2. Manufacturing dimensional tolerance and their technical requirement compliance

Fig.9. Effect of slip coefficient on temperature field of continuous phase evolution zone

Fig.10. Temperature distribution among the symmetric plane

Fig.11. Max coupling temperature vs. slip outer circle of symmetrical plane

Fig.12. Continuous phase evolution zone thickness distribution curve outer circle of symmetrical plane

Fig.13. Max continuous phase evolution among zone thickness vs. slip coefficient

Fig.14. Distribution law of thermal⁃fluid ⁃solid coupling among outer circle of the symmetrical plane

Fig.15. Distribution law of elastic among outer pressure positive stress among outer circle of the symmetrical plane

Fig.16. Distribution law of viscous drag shear stress among outer circle of the symmetrical plane

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