• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.10
• /
• pp.1513-1519
• /
• 2010

Recently, on-line process monitoring systems using sensors are being extensively used to produce highquality products. However, the difficulty in installing the sensors within the mold in the cases of micro-molds, optical molds, and molds with complex structures is a serious disadvantage of such process monitoring systems. In this study, the quantitative index of a process monitoring system was evaluated with the mold cavity pressure and the nozzle pressure for the injection molding machine. In order to evaluate the effect of the nozzle pressure, we performed correlation analysis for the weight of the molded product. We also examined the control characteristics of the injection molding machine by analyzing the effect of multistage injection speed, holding pressure, and injection pressure limit on the process monitoring data.

• Journal of Practical Engineering Education
• /
• v.9 no.2
• /
• pp.119-124
• /
• 2017

In injection molding process, the runner system of the mold is a flow path for filling the cavity of the molded part during the advance of the screw by the force of the hydraulic cylinder, which involves the filling and packing process of the molten resin. Thus, the sprue, runner and gate greatly affect the appearance of the molded part, the physical properties of the resin, the dimensional accuracy and the molding cycle etc. Feed systems with incorrect runner and gate designs cause various molding defects, So it is important to maintain the optimum runner balance to prevent these defects. In order to improve the knowledge of practical mold technology, which is applied to the manufacturers of injection molds, a training model of the mold technology process is presented based on the technical guidance on the technical difficulties.

• Transactions of the KSME C: Technology and Education
• /
• v.1 no.2
• /
• pp.167-177
• /
• 2013

The use of mechanical anastomosis coupler instead of sutures has been increasing in microvascular anastomosis surgery. However, non-biodegradable anastomosis coupler has problems such as not only inflammatory reaction but also remaining permanently in operation wound. Therefore, we fabricated biodegradable anastomosis coupler using injection molding process to overcome the limitation of non-biodegradable anastomosis coupler. In various injection molding process conditions, the shrinkage was calculated with different cylinder temperatures and injection molding pressures and anastomotic strength was measured. As a result, changes in shrinkage hole part larger than the pin part. In addition, the shrinkage in the cylinder at higher temperatures increase. However, the higher the injection pressure, shrinkage tends to decrease, respectively. In-vitro degradation behavior of PCL anastomotic coupler evaluated for 12 weeks, water uptake was increased and molecular weight was accompanied by a reduction in mass of the biological degradation and reduction of anastomotic strength was confirmed. However, decreased levels of anastomotic strength enough to exceed the requirements of preclinical surgery, PCL microvascular anastomosis coupler suitable candidate materials that could identify.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.11 no.6
• /
• pp.24-30
• /
• 2002

The friction/wear testing has been carried out for investigating the tribological characteristics between a conventional screw and tribotreated one. The tribotreated screw is manufactured by blasting a fine polymer power to the heat-treated surface of the conventional screw. The injection molding pressure that is developed between the screw and the cylinder has been applied to the rubbing surface on the specimen in a pin-on-disk wear tester. The measured results show that the friction coefficient and wear rate of a tribotreated screw are relatively low compared with the conventional one. This means that the tribotreated screw may be recommended for using an injection mold machine.

• Transactions of The Korea Fluid Power Systems Society
• /
• v.4 no.2
• /
• pp.21-27
• /
• 2007

This paper deals with the issue of trajectory tracking control of a clamping cylinder for injection moulding machine, which is directly driven by speed controlled hydraulic pump in combination with AC servomotor. As a fundamental step prior to tracking controller design, feedback control system is developed by implementing a position control loop parallel with a system pressure control loop. A sliding mode controller combining velocity feedforward scheme is developed for enhancing the tracking performance. Consequently a significant reduction in tracking error is achieved for both position and pressure control applications.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.06a
• /
• pp.382-391
• /
• 2001

This paper presents tribological results of the screw materials, which include the conventional screw and newly developed one. The tribotreated screw is manufactured by applying the polymer power to the heat treated surface of the screw. The injection pressure which is developed between the screw and the cylinder has been applied to the rubbing surface of the specimen in a pin-on-disk wear tester. The measured results show that the friction coefficient and wear rate of a tribotreated screw are low compared to the conventional one.

• Design & Manufacturing
• /
• v.13 no.4
• /
• pp.1-9
• /
• 2019

In-mold Coating is a method that can simultaneously perform injection molding and surface coating in injection mold. The material used for coating is two-component polyurethane which is composed of polyol and isocyanate. L-type mixing head can be used to mix polyol and isocyanate uniformly, and inject them inside the mold cavity. The surface quality of the injection molded products by using in-mold coating depends on the mixing uniformity between main agent and hardener. In this study, flow analysis was performed to design a mixing head for uniform mixing of two-component polyurethane. Especially the effects of design parameters of mixing head on mixing uniformity and nozzle pressure were investigated. The parameters of mixing head were mixing chamber diameter, cleaning cylinder diameter, nozzle alignment angle in the horizontal and vertical direction, and cleaning piston position. It was found that optimal design values were mixing chamber diameter of 3.5 mm, cleaning cylinder diameter of 5.0 mm, nozzle horizontal/vertical alignment angles of 140°/160°, and cleaning piston position of 1.8 mm. The optimal values would be used to develop a two-component mixing head achieving an uniform mixing for in-mold coating.

• Design & Manufacturing
• /
• v.18 no.2
• /
• pp.41-50
• /
• 2024

In this study, experimental design methods were used to derive optimal process conditions for improving the thickness uniformity of a 0.40 mm, 3.5 inch light guide panel. Process mapping and expert group analysis were used to identify factors that influence the thickness of injection molded products. The key factors identified were mold temperature, mold temperature, injection speed, packing pressure, packing time, clamp force, and flash time. Considering the resin manufacturer's recommended process conditions and the process conditions for similar light guide plates, a three-level range was selected for the identified influencing factors. L27 orthogonal array process conditions were generated using the Taguchi method. Injection molding was performed using these L27 orthogonal array to mold the 3.5 inch light guide plates. Thickness measurements were then taken, and the results were analyzed using the signal-to-noise ratio to maximize the CpK value, leading to the determination of the optimal process conditions. The thickness uniformity of the product was analyzed by applying the derived optimum process conditions. The results showed a 97.5% improvement in the Cpk value of 3.22 compared to the process conditions used for similar light guide plates.

• Journal of Drive and Control
• /
• v.10 no.3
• /
• pp.21-26
• /
• 2013

This paper presents a robust motion tracking control of a cylinder-toggle servomechanism for injection molding machines. Virtual design model has been developed for a five-point type toggle mechanism. A sliding function is defined and combined with PID control to accommodate mismatches between the real plant and the linear model used. From tracking control simulations, it is shown that significant reduction in position tracking error is achieved with clamping force build-up through the use of proposed control scheme.

• Journal of Drive and Control
• /
• v.11 no.2
• /
• pp.9-15
• /
• 2014

This paper deals with the issue of force synchronizing control for the clamping servomechanism of injection molding machines. Prior to the controller design, a virtual design model has been developed for the clamping mechanism with hydraulic systems. Then, a synchronizing controller is designed and combined with an adaptive feedforward control in order to accommodate the mismatches between the real plant and the linear model plant used. As a disturbance, the leakage due to the ring gap with relative motion in the cylinder has been introduced. From the robust force tracking simulations, it is shown that a significant reduction in the force synchronizing error is achieved through the use of a proposed control scheme.