The Utilization of Flow Control During Multi-Cavity Injection Molding Processes

Materials ◽  
2004 ◽  
Author(s):  
Gregory S. Layser ◽  
John P. Coulter ◽  
Gregory M. Bielawiec
Keyword(s):  
Injection Molding ◽  
Flow Control ◽  
Flow Rate ◽  
Control Valve ◽  
Polymer Melt ◽  
Processing Parameters ◽  
Industrial Manufacturing ◽  
Mechanical Valves ◽  
Control Concept ◽  
Plastic Parts

Process control is an important factor for improving the performance and consistency of thermoplastic parts manufactured by injection molding processes. A critical process parameter for manufacturing of high quality plastic parts is cavity pressure. This paper presents a continuation of a numerical based study of the utilization of flow control specifically for cold runner applications in multi-cavity injection molding processes. A cold runner system supplying polymer melt to a multi-cavity mold incorporating several types of mechanical valves in the runner systems was modeled and manufactured. Each valve independently controls the flow and pressure to its portion of the mold. The goal of the numerical simulation phase of the present investigation was to numerically simulate and thus validate a physical capability to modify the filling of individual cavities during injection molding of products utilizing multi-cavity tooling. A decision was made to attempt to do so by physically controlling the flow rate of polymer into each cavity. The tooling set was made adaptive through the incorporation of custom designed control valves into the runner channels leading to each product cavity. Simulations of both the overall adaptive tooling concept and the specific control valve designs were performed with LCP and PPS as a molding material. It was concluded that the flow control concept developed was numerically validated [1–3], and it was shown that the valve system proposed here is applicable to control melt flow through cavities at industrial manufacturing facilities. The adaptive tooling developed and simulated during the current investigation yielded significant variations in both processing parameters and resultant product quality in response to in-tooling control valve adjustments. It was found that by changing valve angle settings, the flow rate to each cavity could be controlled individually without degrading desired material properties. In an attempt to further promote the flow control concept, an experimental mold was developed and forms the basis for this paper. Preliminary experimental results verifying previous work and the future directions for the continuing project are also discussed.

Numerical Simulation in a Multiple Flow Control Valve System of Polymer Melt During Injection Molding Processes

2005 ◽  
Author(s):  
Gregory S. Layser ◽  
John P. Coulter
Keyword(s):  
Injection Molding ◽  
Flow Control ◽  
Current System ◽  
Control Valve ◽  
Polymer Melt ◽  
Flow Control Valve ◽  
Flow Modulation ◽  
Valve System ◽  
Plastic Parts ◽  
Critical Process

Process control is an important factor for improving the performance and consistency of thermoplastic parts manufactured by injection molding processes. A critical process parameter for manufacturing of high quality plastic parts is cavity pressure. This paper presents a continuation of a numerical based study of flow control utilized during multi-cavity injection molding processes and focuses in more detail on multiple flow control valve systems, since the valves are coupled with one injection source. The capabilities of the current system design are limited by multiple valve interactions, which may produce undesirable effects in regards to flow modulation and pressure distribution in multiple cavities and should be studied further. Understanding the flow modeling details through a single valve system is essential, thereby reducing the computational work involved with a multiple valve system.

Numerical Simulation of Polymer Melt Flow Control for a Multi-Cavity Mold During Injection Molding Processes

2003 ◽  
Author(s):  
Ahmet Pinarbasi ◽  
Gregory S. Layser ◽  
John P. Coulter
Keyword(s):  
Numerical Simulation ◽  
Injection Molding ◽  
Flow Control ◽  
Polymer Melt ◽  
Volumetric Flow Rate ◽  
Melt Flow ◽  
Valve System ◽  
Control Concept ◽  
Flow Through ◽  
Plastic Parts

Process control is an important factor for improving the performance and consistency of thermoplastic parts manufactured by injection molding processes. A critical process parameter for manufacturing of high quality plastic parts is cavity pressure. This paper presents direct numerical simulation results of a new manufacturing concept developed to improve injection molding processing for all runner types by monitoring shot to shot product quality and controlling the filling of multi-cavity molds in real time. A cold runner system supplying polymer melt to a two-cavity mold incorporating mechanical valves in the runner systems was modeled. Each valve was controlled independently to meter flow and pressure to its portion of the mold. Simulations were performed for two different materials: PPS Ryton R-4-200 and LCP Vectra E130D-2. Shear-rate dependence of viscosity of the materials is modeled through the Cross rheological equation. Flow rates and maximum shear-rates through valves were calculated and the results of the simulations were analyzed to validate the concept of individual cavity filling modification. Flow through one valve system leading to a single cavity was simulated first, followed by flow through two-valve system for filling two cavities. For one valve simulations, pressure at the inlet was specified, whereas for flow through two-valve system, volumetric flow rate at the inlet was supplied for simulations. It was concluded that the flow control concept developed was numerically validated, and it was shown that the valve system proposed here is applicable to control melt flow through cavities at industrial manufacturing facilities. The future directions for the continuing project are also discussed.

Analysis and Modification of the Design of Fluid Power Control System for the Improvement of Product Quality

2013 ◽  
Author(s):  
Tahany W. Sadak ◽  
Taha E. Mkawee
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
System Performance ◽  
Dynamic Performance ◽  
Control Valve ◽  
Operating Conditions ◽  
Flow Control Valve ◽  
Supply Pressure ◽  
System Designs ◽  
Proportional Flow

This research investigation is focused on providing system performance under different operating conditions, with special focus on variations in the supply pressure. The investigations have been carried out for different system designs. The analysis of the results introduces the effect of system designs on its static and dynamic performance. Also, the investigations provide the effect of variations of system operating conditions and load value. A hydraulic system has been designed with variable velocity, pressure and load. The detailed examination has been carried out on a system that consists of a hydraulic power supply unit, control valves (pressure control valve, flow control valve, throttle valve and directional control valve). We have investigated the effect of adding a flow control valve (FCV) in the chosen circuit and also replacing the FCV with a proportional flow control valve (PFCV). In order to study the effect of this valve on system performance we examine the role of change of operating conditions and loading values on the system performance. Thus the displacement and speed of the piston of the hydraulic cylinder has been experimented under different values of supply pressure, flow rate, and load. We make this investigation to develop the performance evaluation by replacing the (FCV) by proportional flow control valve (PFCV) via position control so that one can achieve the static and dynamic performance of the system more accurate. Apparent improvement in flow rate ranges from 8% to 29.5% and dynamic response from 30 to 64%. The results reveal that this methodology allows one to achieve high quality of the product.

Modeling and Optimal Control of a Variable-Speed Centrifugal Pump With a Pipeline

2016 ◽  
Author(s):  
Cristian F. Jaimes Saavedra ◽  
Sebastian Roa Prada ◽  
Jessica G. Maradey Lázaro
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Flow Control ◽  
Flow Rate ◽  
Power Efficiency ◽  
Control Valve ◽  
Operating Point ◽  
Variable Frequency ◽  
Centrifugal Pumps ◽  
Variable Frequency Drive

Pumping processes often require different operating conditions for the same pipeline. The conditions downstream in the pipeline can change in such a way that the pressure at the discharge of the pump may vary, which automatically introduces changes in the flow supplied by the pump into the pipeline due to the head vs flow characteristic curve of the pump. Even under varying pipeline pressure conditions, it may be necessary to keep the flow discharge of the pump constant. The two most commonly used control strategies for flow control with centrifugal pumps are by means of a fixed-speed pump and a control valve at the outlet of the pump, or by means of a variable frequency drive which avoids the need for the control valve. It has been demonstrated that the approach with the fixed-speed pump and the control valve provides poor power efficiency results, so a variable frequency drive is normally the solution of choice in industry applications. The use of a variable frequency drive allows reaching the flow required by the system without changing the physical characteristic of the pump or pipeline, i.e., it is not necessary to shut the system down to replace the impeller of the pump. However, affinity laws of centrifugal pumps dictate that a change in the rotational speed of the impeller shifts the characteristic curves of the pump, not only the flow vs head curve, but also the efficiency curves, among others. Besides, searching for a different operating point by changing the speed of the pump does not necessarily guarantees optimal operating power efficiency. This paper proposes an optimization approach where a compromise is made between flow control and power efficiency by minimizing the error in the flow rate while at the same time maximizing the power efficiency. To accomplish this goal, this paper presents the modeling of the pump and pipeline, and the design of a linear quadratic regulator control for the fluid flow passing through a given pipeline. The fluid under consideration is water. The mathematical model of the overall system is derived by considering the model of an AC motor, the pump and the hydraulic circuit. Then, with the help of the software MATLAB, the controller was designed and implemented with the linearized mathematical model. The actuator of the control system is the variable frequency drive that changes the speed of the impeller to adjust the flow rate to the required operating point under different loading conditions. The results show the behavior of the compensated system with the optimal controller. In practice, the control system must take into account the constraints of the control effort, which means, the frequency of the pump must be kept within safe values to achieve proper functioning of the pumping system.

Development of Novel Particle Excitation Flow Control Valve for Stable Flow Characteristics

2016 ◽  
Vol 10 (4) ◽  
pp. 540-548 ◽  
Author(s):  
Daisuke Hirooka ◽  
◽  
Tomomi Yamaguchi ◽  
Naomichi Furushiro ◽  
Koichi Suzumori ◽  
...  
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Control Valve ◽  
Flow Control Valve ◽  
Different Types ◽  
Valve Opening ◽  
Working Principle ◽  
Stable Flow ◽  
Air Flow Control

The authors have previously developed a compact, light-weight air flow control valve, which realizes continuous flow control. The vibration produced by a piezoelectric device (PZT) was used to excite particles confined in a flow channel to control the valve opening for the developed control valve. Therefore, the voltage applied to the PZT can be changed to continuously control the flow rate. A new working principle was developed for the control valve to stabilize flow rate characteristics. Different types of particles were used to change the valve opening condition. A prototype was manufactured to demonstrate the effectiveness of the control valve.

Optimization of the Injection Molding Process Parameters Based on Moldflow and Orthogonal Experiment

2013 ◽  
Vol 561 ◽  
pp. 239-243 ◽  
Author(s):  
Yong Nie ◽  
Hui Min Zhang ◽  
Jia Teng Niu
Keyword(s):  
Injection Molding ◽  
Orthogonal Experiment ◽  
Mold Temperature ◽  
Processing Parameters ◽  
Influential Factors ◽  
Injection Molding Process ◽  
Range Analysis ◽  
Molding Process ◽  
Melt Temperature ◽  
Plastic Parts

This article is using Moldflow analysis and orthogonal experimental method during the whole experiment. The injection molding process of motor cover is simulated under various technological conditions.After forming the maximum amount of warpage of plastic parts for evaluation.According to the range analysis of the comprehensive goal, the extent of the overall influence to the processing parameters, such as gate location, melt temperature, mold temperature and holding pressure is clarified.Through analyzing the diagrams of influential factors resulted from the simulation result,the optimized process parameter scheme is obtained and further verified by simulation.

An Investigation Into the Characteristics of a Two Dimensional “2D” Flow Control Valve

2001 ◽  
Vol 124 (1) ◽  
pp. 214-220 ◽  
Author(s):  
J. Ruan ◽  
R. Burton ◽  
P. Ukrainetz
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
Structural Parameters ◽  
Control Valve ◽  
Favorable Effect ◽  
Flow Control Valve ◽  
Two Dimensional ◽  
System Pressure ◽  
Hydrostatic Force ◽  
2D Flow

In hydraulic servo systems, a pilot stage is often used to reduce the influence of Bernoulli’s forces and frictional forces when trying to accurately position a spool. A unique pilot controlled valve (defined as a two dimensional or “2D” flow control valve), which utilizes both rotary and linear motions of a single spool, is presented. The rotary motion uses a spiral groove in the sleeve combined with high and low pressure holes on the spool land to control the pressure in the spool chamber, while the linear motion of the spool is actuated by a hydrostatic force. Both linear theory and numerical simulation are adopted in the investigation of the characteristics of the valve. A criterion for stability is established from a linearized model of the valve. The analysis establishes the effects that certain structural parameters have on the valve’s static and dynamic characteristics. Special experimental procedures were designed to obtain properties such as mechanical stiffness, leakage flow rate, and dynamic response under different structural parameters and system pressure. It was shown that the leakage through the spool-sleeve clearance had a favorable effect on the valve stability. Theoretical and experimental results show that it is necessary to establish a balance between the static and dynamic performance in establishing appropriate structural parameters. It is also shown that the 2D flow control valve can demonstrate a high speed of response, while maintaining the pilot flow rate at a low level.

An Investigation Into the Characteristics of a “2D” Flow Control Valve

2000 ◽  
Author(s):  
J. Ruan ◽  
R. Burton ◽  
P. Ukrainetz
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
High Speed ◽  
Structural Parameters ◽  
Control Valve ◽  
Favorable Effect ◽  
Flow Control Valve ◽  
System Pressure ◽  
Hydrostatic Force ◽  
2D Flow

Abstract In hydraulic servo systems, a pilot stage is often used to reduce the influence of Bernoulli’s forces and frictional forces when trying to accurately position a spool. A unique pilot controlled valve, (defined as a “2D” flow control valve), which utilizes both rotary and linear motions of a single spool, is presented. The rotary motion uses a spiral groove in the sleeve combined with high and low pressure holes on the spool land to control the pressure in the spool chamber, while the linear motion of the spool is actuated by a hydrostatic force. Both linear theory and numerical simulation are adopted in the investigation of the characteristics of the valve. A criterion for stability is established from a linearized model of the valve. The analysis establishes the effects that certain structural parameters have on the valve’s static and dynamic characteristics. Special experimental procedures were designed to obtain properties such as mechanical stiffness, leakage flow rate, and dynamic response under different structural parameters and system pressure. It was shown that the leakage through the spool-sleeve clearance had a favorable effect on the valve stability. Theoretical and experimental results show that it is necessary to establish a balance between the static and dynamic performance in establishing appropriate structural parameters. It is also shown that the 2D flow control valve can demonstrate a high speed of response, while maintaining the pilot flow rate at a low level.

New Designs in Fuel Dispensing System to Control Maximum Flow of Volatile Liquid

2017 ◽  
Vol 868 ◽  
pp. 75-80
Author(s):  
Ya Jun Liu ◽  
Shu Yan Zhan ◽  
Jia Kun Ye ◽  
Wen Hua Xie
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
Oil And Gas ◽  
Control Valve ◽  
Maximum Flow ◽  
Control Mode ◽  
Theoretical Research ◽  
Flow Control Valve ◽  
Cavitation Phenomenon ◽  
Volatile Liquid

The dispenser is a fuel pumping and measurement device used in the service station. During the refueling process of volatile liquid, the cavitation phenomenon occur easily due to the large flow rate. The serious cavitation will not only reduce the pumping efficiency, produce loud work noise, but also aggravate the pollution of oil and gas and the energy consumption of the system. Therefore, it is necessary to control the maximum flow rate of the pump. Based on this problem, this paper firstly designs a new flow control valve, and a method of mathematical modeling is proposed to analyze the flow field distribution and the working principle of the whole device based on Euler equation and Bernoulli equation. Then we combine this new hydraulic device to the variable frequency dispenser, a new design of the dispenser structure and a control mode of the maximum flow are proposed. The theoretical research shows that the maximum flow can be limited by optimizing diameter ratio of that flow control valve.

Effect of Micro-Injection Molding Processing Conditions on the Replication and Consistency of a Dense Network of High Aspect Ratio Microstructures

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
John W. Rodgers ◽  
Meghan E. Casey ◽  
Sabrina S. Jedlicka ◽  
John P. Coulter
Keyword(s):  
Injection Molding ◽  
Flow Rate ◽  
Mold Temperature ◽  
Processing Parameters ◽  
Molding Process ◽  
Micro Injection Molding ◽  
Fluid Behavior ◽  
Replication Quality ◽  
Average Standard Error ◽  
Experimental Trials

When molding macroscale polymer parts with a high density of microfeatures (>1 × 106/cm2), a concern that presents itself is the ability to achieve uniform replication across the entire domain. In the given study, micro-injection molding was used to manufacture microfeatured polymer substrates containing over 10 × 106 microfeatures per cm2. Polystyrene (PS) plates containing microtopography were molded using different processing parameters to study the effect of flow rate and mold temperature on replication quality and uniformity. Flow rate was found to significantly affect replication at mold temperatures above the glass transition temperature (Tg) of PS while having no significant effect on filling at mold temperatures below Tg. Moreover, replication was dependent on distance from the main cavity entrance, with increased flow rate facilitating higher replication differentials and higher replication near the gate. Simulation of the molding process was used to corroborate experimental trials. A deeper understanding of polymer fluid behavior associated with micro-injection molding is vital to reliably manufacture parts containing consistent microtopography (Note: Values are expressed in average ± standard error).

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