Injection Foam Molding Machine Die Interval Control
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Solution Overview
Problem
Conventional injection foam molding machines face challenges in accurately aligning hydraulic cylinders, leading to gaps between the mold and the molded product, which results in swirl marks or silver formation, and require expensive ball screw units to handle heavy die plates.
Innovation Solution
The injection foam molding machine employs hydraulic cylinders fixed to either the fixed or movable die plates, with a die-plate-interval adjusting unit using a trapezoidal screw and nut mechanism, controlled by a servo motor, to precisely adjust the mold interval and prevent negative pressure during foaming, ensuring accurate and reproducible molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hydraulic cylinders are used to widen the mold interval for foaming, then the mold can be opened to allow resin expansion, but alignment accuracy between multiple hydraulic cylinders deteriorates due to gear backlashes, causing gaps between the mold and molded product
Solution Approach 1:
The patent replaces the gear-based mechanical transmission system (bevel gear and worm gear) with a direct hydraulic linkage system. The hydraulic cylinder's piston rod directly connects to the mold via a linkage mechanism, eliminating intermediate gears and their associated backlashes. This direct mechanical connection ensures precise and consistent positioning of the mold during the foaming process, resolving the alignment accuracy issue while maintaining the ability to open the mold for resin expansion.
2Manufacturing precision
If ball screw units with large capacity are used to accurately drive heavy die plates, then positioning accuracy is improved, but the facility cost increases considerably
Solution Approach 1:
The patent employs a hydraulic cylinder with a linkage mechanism to drive the mold opening and positioning, replacing the traditional ball screw unit. The hydraulic system provides sufficient force to handle heavy die plates while achieving the required positioning accuracy through precise control of the hydraulic pressure and linkage geometry. This approach reduces facility cost by using a more economical hydraulic system compared to high-capacity ball screw units, while still achieving the necessary positioning precision for accurate molding.
3Productivity
If the mold is opened rapidly to expand the foamable resin, then productivity is improved, but the expanding speed of resin cannot follow the retracting speed of the mold, generating gaps and surface defects
Solution Approach 1:
The patent implements a dynamic control system that adjusts the mold opening speed in real-time based on the resin expansion characteristics. The hydraulic cylinder's piston rod movement is controlled through a linkage mechanism that allows variable speed operation. The system can rapidly open the mold initially, then automatically reduce the opening speed to match the resin expansion rate, preventing gaps and surface defects while maintaining high overall productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures accurate molded products by controlling the expanding speed of the resin foam, eliminating swirl marks and silver streaks, and reduces the need for expensive ball screw units by using a more cost-effective trapezoidal screw mechanism.
Implementation Method 1
a die-plate-interval adjusting unit which adjusts a distance over which the movable die plate is moved by the drive units, in which the drive units, which are hydraulic cylinders that drive a ram to an activation end, are fixed to the fixed die plate or the movable die plate, the die-plate-interval adjusting unit is fixedly provided on an alternate one of the die plates at a position facing the drive units, and an adjustment end of the interval adjusting unit is abutted to a leading end of an activating rod of the hydraulic cylinders of the drive units
Implementation Method 2
drive units, which are hydraulic cylinders that drive a ram to an activation end
Implementation Method 3
a foamable molten resin injected and filled within a mold cavity is foamed by slightly opening a mold
Data Source
AI summary
An injection foam molding machine according to the present invention includes: a clamping unit that moves a movable die plate 3 relative to a fixed die plate 2 to clamp the die plates; a fixed side mold attached to the fixed die plate 2; a movable side mold attached to the movable die plate 3; a plurality of drive units 50 that widen an interval between both of the die plates 2 and 3; and a die-plate-interval adjusting unit 60 that adjusts a distance over which the movable die plate 3 is moved by the drive units 50, and when a molten foam resin is foamed, an inner-side interval within the mold cavity is determined, and thus an accurate molded product can be obtained.