Study on External Gas-Assisted Mold Temperature Control with the Assistance of a Flow Focusing Device in the Injection Molding Process

In the injection molding field, the flow of plastic material is one of the most important issues, especially regarding the ability of melted plastic to fill the thin walls of products. To improve the melt flow length, a high mold temperature was applied with pre-heating of the cavity surface. In this paper, we present our research on the injection molding process with pre-heating by external gas-assisted mold temperature control. After this, we observed an improvement in the melt flow length into thin-walled products due to the high mold temperature during the filling step. In addition, to develop the heating efficiency, a flow focusing device (FFD) was applied and verified. The simulations and experiments were carried out within an air temperature of 400 °C and heating time of 20 s to investigate a flow focusing device to assist with external gas-assisted mold temperature control (Ex-GMTC), with the application of various FFD types for the temperature distribution of the insert plate. The heating process was applied for a simple insert model with dimensions of 50 mm × 50 mm × 2 mm, in order to verify the influence of the FFD geometry on the heating result. After that, Ex-GMTC with the assistance of FFD was carried out for a mold-reading process, and the FFD influence was estimated by the mold heating result and the improvement of the melt flow length using acrylonitrile butadiene styrene (ABS). The results show that the air sprue gap (h) significantly affects the temperature of the insert and an air sprue gap of 3 mm gives the best heating rate, with the highest temperature being 321.2 °C. Likewise, the actual results show that the height of the flow focusing device (V) also influences the temperature of the insert plate and that a 5 mm high FFD gives the best results with a maximum temperature of 332.3 °C. Moreover, the heating efficiency when using FFD is always higher than without FFD. After examining the effect of FFD, its application was considered, in order to improve the melt flow length in injection molding, which increased from 38.6 to 170 mm, while the balance of the melt filling was also clearly improved.

Load Carrying Capacity of Drift Pin Joint of Cross Laminated Timber (CLT) with Steel Insert Plate

Cross Laminated Timber (CLT) is a structural plate element which is approved in Europe and is intended to be approved in Japan. It consists of small dimension laminae, in which laminae parallel and perpendicular to longitudinal direction are interlaminated. We performed tensile tests for the drift pin joint with steel insert plate. Specimen consisted of CLT was made from Japanese cedar laminae (thickness of laminae t = 30mm, five laminae were layered), with steel drift pin plate. Odd-numbered layers were parallel to the longitudinal axis, and even-numbered layers were perpendicular to the longitudinal axis. The experimental parameters were edge distances (3d, 4d and 7d), end distances (3d, 4d and 7d) and diameters of pin (12 and 16 mm) and the replication were three respectively. Initial stiffness was lower than the results of glulam drift pin joint loaded in parallel to the grain, however second stiffness after the yield of drift pin was higher because the lateral compression occurred at even-numbered layers. Additionally, ductility was higher because split failures around the pin were prevented by the glued effect of interlaminated layers. As the characteristic value of test results, initial stiffness K, yield load Py, maximum load Pmax, indicated the effect of the difference of the diameter of the pin, while deformation capacity indicated the effect of edge distance.

Stress Analysis of Reinforced Nozzle-Cylindrical Shell Intersection Under Internal Pressure or Nozzle Radial Thermal Expansion

Two normally intersecting cylinders under different internal pressures in each of the cylinders is solved analytically. The inclusion of nozzle fillet, insert plate and inner nozzle broadens the applicability of this analytical method in the design and analysis of pressurized cylinder-to-cylinder intersection. The current numerical solution scheme has been incorporated in the computer code NUTSHELL. Comparisons of NUTSHELL solutions and experimental or finite element results have also been presented.

Shell Solution for Reinforced Cylinder to Sphere Intersection

To reduce the stress level at nozzle to spherical pressure vessel intersections, reinforcement is generally added to the sphere, the nozzle or both. This paper describes the development of a computer code using closed-form solutions to analyze this problem. Up to seven components can be considered in the model: inner and outer nozzles each connected to pipes; an insert plate; spherical shell; and cylindrical vessel connected to the sphere. All three forces and moments on each nozzle as well as internal pressure and simple thermal loading are considered. Thin shell theory is used for each component. Due to the complexity of the exact solution for the sphere, asymptotic solutions valid for both the shallow and steep regions are used. This solution allows parameter studies to be performed efficiently for various reinforcement geometries.