Structural Optimization of a Dual-Sensing Module for Temperature and Pressure Measurement in Injection Mold Cavity

Author(s):  
Zhaoyan Fan ◽  
M. Haris Hamid ◽  
Robert X. Gao ◽  
Stephen Johnston ◽  
David Kazmer

This paper presents the design and optimization of a temperature-pressure sensing module that is structurally integrated into an injection mold. The sensor extracts energy from the polymer melt pressure differential during the injection molding process and uses ultrasonic pulses as the wireless information transmission carrier. The dimension of the piezo ceramic rings that scavenge energy from the mold pressure change is optimized to minimize the volume of the sensor while maintaining the minimum Signal-to-Noise Ratio (SNR) required for reliable signal reception. An analytical expression of the optimal dimension is presented. Based on the optimized design, the sensor module package, together with the injection mold steel and the polymer melt that flows over the sensor into the mold cavity, was modeled using the finite element method. To quantify the behavior of polymer melt and its effect on sensors output, a coupled fluid-structure interaction analysis was performed to examine the mold-melt interface, by using the solution-looping and mesh-morphing techniques. A case study of the sensor design for a 40 mm thick injection mold was investigated by using the presented optimization method and FEA model. Results show that the volume of the piezo stack can be reduced to 0.7 cm3 while meeting the minimum SNR requirement. The minimum insulator thickness of 1 mm is presented by the FEA model to maintain the thermal induced error below 0.5%.

Author(s):  
Zhaoyan Fan ◽  
Robert X. Gao

This paper presents the design and performance analysis of a self-energized wireless sensor capable of simultaneous pressure-temperature dual sensing from within a mold cavity. The sensor extracts energy from the polymer melt pressure differential during the injection molding process and uses ultrasonic pulses as the wireless information transmission carrier. Simultaneous acquisition of melt temperature and pressure and differentiation of the two parameters at the signal receiver's end are made possible by variations of two parameters related to the ultrasonic pulses: the number of ultrasound pulses and the carrier frequency. While the pressure is discretized and translated proportionally into a corresponding number of pulses by a threshold modulator, a temperature-sensitive oscillator module converts the melt temperature variations into a shift of the ultrasound carrier frequency. To quantitatively evaluate the effectiveness of transmission and retrieval of the dual sensing data, an analytical model is established that relates the sensor design to the molding process parameters. The developed technique is validated by the experimental data from a real physical model.


Author(s):  
Charles B. Theurer ◽  
Li Zhang ◽  
David Kazmer ◽  
Robert X. Gao

This paper presents the design, analysis, and validation of a self-energized piezoelectric pressure sensor that extracts energy from the pressure differential of the polymer melt during the injection molding process. To enable a self-energized sensor design, an analytical study has been conducted to establish a quantitative relationship between the polymer melt pressure and the energy that can be extracted through a piezoelectric converter. Temperature and pressure are monitored during an injection molding cycle and the performance of the piezoelectric element is evaluated with respect to a mechanically static, electrically transient model. In addition to corroboration of the proposed model, valuable statistical information about the working temperature in the prototype sensor will prove very useful in the package design of molding cavity sensors. A linear model examining the energy conversion mechanism due to interactions between the mechanical strain and the electric field developed within the piezoelectric device is established. This model is compared to the functional prototype design to evaluate the relevance of the assumptions and accuracy. The presented design enables a new generation of self-energized sensors that can be employed for the condition monitoring of a wide range of high-energy manufacturing processes.


2012 ◽  
Vol 468-471 ◽  
pp. 1013-1016 ◽  
Author(s):  
Hua Qing Lai

Molding is one of the most versatile and important processes for manufacturing complex plastic parts. It is a method of fabricating plastic parts by utilizing a mold or cavity that has a shape and size similar to the part being produced. Molten polymer is injected into the cavity, resulting in the desired part upon solidification. The injection-molded parts typically have excellent dimensional tolerance and require almost no finishing and assembly operations. But new variations and emerging innovations of conventional injection molding have been continuously developed to offer special features and benefits that cannot be accomplished by the conventional injection molding process. This study aims to improving the life of stereolithography injection mold.


Author(s):  
Wojciech Bejgerowski ◽  
Satyandra K. Gupta

The runner system in injection molding process is used to supply the polymer melt from injection nozzle to the gates of final part cavities. Realizing complex multi-material mechanisms by in-mold assembly process requires special runner layout design considerations due to the existence of the first stage components. This paper presents the development of an optimization approach for runner systems in the in-mold assembly of multi-material compliant mechanisms. First, the issues specific to the in-mold assembly process are identified and analyzed. Second, the general optimization problem is formulated by identification of all parameters, design variables, objective functions and constraints. Third, the implementation of the optimization problem in Matlab® environment is described based on a case study of a runner system for an in-mold assembly of a MAV drive mechanism. This multi-material compliant mechanism consists of seven rigid links interconnected by six compliant hinges. Finally, several optimization approaches are analyzed to study their performance in solving the formulated problem. The most appropriate optimization approach is selected. The case study showed the applicability of the developed optimization approach to runner systems for complex in-mold assembled multi-material mechanism designs.


2008 ◽  
Vol 44-46 ◽  
pp. 85-89
Author(s):  
J.J. Jia ◽  
Zheng Hao Ge ◽  
Y. Li

For injection mold with core, during the injection molding process, the pressure on the core is usually uneven and will cause the core to deform. In this paper, on the basis of some predigestions and assumptions of the model, formulas for forecasting the deformation of the circular cross-section and the rectangular cross-section cores under three different injection ways are analyzed. The theoretical analysis results of a core with special section are validated through finite element software. At the end, some suggestions are given to minish the core deformation when the calculation value is too large.


Author(s):  
Chuanyang Wang ◽  
Shuai Hu ◽  
Qiubo Qian ◽  
Xuanxuan Shen

The 3D models of gating system, ejection mechanisms and cooling system of the swtich shell for injection mold are designed by using Pro/ENGINEER software. MOLDFLOW is utilized for CAE analysis. Three schemes are obtained by changing the gate location during the injection molding process. After comparing the volume shrinkage during injection, shrink marks index, filling time and the injection pressure, the best scheme is obtained. According to the optimal scheme, the injection mold is designed. The results showed that simulation analysis method can not only improve the successful probability of mold trial, but also shorten the production development cycle of developing product.


2018 ◽  
Vol 145 ◽  
pp. 02006
Author(s):  
Margarita Natova ◽  
Ivan Ivanov ◽  
Sabina Cherneva ◽  
Maria Datcheva ◽  
Roumen Iankov

During conventional polymer injection molding, flow- and weld lines can arise at the molded parts caused by disturbed polymer melt flow when it crosses different parts of the equipment. Such processed plastic goods have discrete zones of inhomogeneities of very small dimensions. In order to stabilize the melt flow and to equalize dimensions of such defective products, an approach for pulse injection molding is applied during production of polymer packagings. Testing methods used for evaluation of macromechanical performance of processed polymer products are not readily applicable to estimate the changes in visual surface obtained during pulse injecting. To overcome this testing inconvenience the performance of processed packagings is evaluated by nanoindentation. Using this method, a quantitative assessment of the polymer properties is obtained from different parts of technological products.


2015 ◽  
Vol 786 ◽  
pp. 210-214
Author(s):  
M.S. Rusdi ◽  
Mohd Zulkifly Abdullah ◽  
A.S. Mahmud ◽  
C.Y. Khor ◽  
M.S. Abdul Aziz ◽  
...  

Computational Fluid Dynamic (CFD) was used to simulate the injection molding process of a tray. The study focuses on pressure distribution and velocity drop during the injection process. CFD simulation software ANSYS FLUENT 14 was utilized in this study. The melt front pressure in the mold cavity shows that it was affected by the shape of mold cavity and filling stage. The melt front pressure will decrease as the flow move further than the sprue but it will increase rapidly when the mold was about to be fully filled. The slight pressure drop was detected when the molten flow meets the rib of the tray. The velocity of higher injection pressure was greater than the lower injection pressure but the velocity rapidly dropped when the melt front fully filled the cavity. The current predicted flow profile was validated by the experimental results, which demonstrates the excellent capability of the simulation tool in solving injection-molding problems.


2013 ◽  
Vol 562-565 ◽  
pp. 1380-1386
Author(s):  
Jian Zhuang ◽  
Da Ming Wu ◽  
Ya Jun Zhang ◽  
Lin Wang ◽  
Xiong Wei Wang ◽  
...  

The flow behaviors for polymer melt at the filling stage in micro injection molding are different from those in conventional injection molding due to the miniaturization of plastic parts. This paper focuses on the study of the effects of three main influencing factors, including the microscale viscosity and wall slip, on melt filling flow in microscale neglected those in conventional injection molding process. The theoretical models and the interrelation of these factors in microscale channels were constructed by means of the model correction method. Then, the micro melt flow behaviors were investigated with comparisons of the available experimental data. The results indicate that the dimensions affect the shear rates and viscous dissipation, which in turn affects the apparent viscosity. Finally, the conclusion is that the melt flow behaviors in microchannels are different from those in macrochannels owing to these significant influencing factors.


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