Cascade Injection Molding Nozzle Throttling for Flow Front Markings
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Solution Overview
Problem
In injection molding, especially cascade injection molding, the use of a gaseous pressure medium in piston-cylinder drives for needle shut-off nozzles leads to sudden opening and explosive injection, causing unwanted flow front markings and weld lines, which are difficult to prevent with existing throttling devices.
Innovation Solution
A check throttle valve with an adjustable throttle and non-return valve is inserted into the pressure medium line to control the opening of nozzles, slowing down the injection pressure and preventing sudden melt flow, while a mechanically coupled liquid pressure medium system or an electrically controllable proportional flow control valve can be used to manage the pressure and flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a gaseous pressure medium is used in piston-cylinder drives for needle shut-off nozzles, then the opening of nozzles is sudden and explosive injection occurs, but this causes unwanted flow front markings and weld lines
Solution Approach 1:
A check throttle valve is introduced as an intermediary device in the pressure medium line between the piston-cylinder drive and the needle shut-off nozzle. This valve mediates the pressure transmission, converting the sudden gaseous pressure impulse into a controlled, gradual opening motion of the nozzle needle, thereby preventing explosive injection and flow front markings while maintaining the benefits of pneumatic actuation
Solution Approach 2:
The check throttle valve dynamically changes the flow parameters of the gaseous pressure medium by restricting and regulating the pressure and flow rate. This parameter control transforms the abrupt pressure release into a gradual, controlled pressure increase, enabling smooth nozzle opening without sudden explosive injection
2Object-affected harmful factors
If throttling devices are provided for each late-opening nozzle to prevent explosive melt injection, then flow front markings are avoided, but the device becomes very expensive and complex
Solution Approach 1:
The check throttle valve is designed as a universal component that can be integrated into the existing pressure medium distribution system. A single valve design serves multiple nozzles, replacing the need for individual complex control arrangements at each nozzle location. The valve performs multiple functions: pressure regulation, flow control, and timing synchronization for cascade injection molding
Solution Approach 2:
The invention merges the throttling function with the existing piston-cylinder drive system by placing the check throttle valve in the shared pressure medium line. This consolidation eliminates the need for separate control systems at each nozzle, reducing overall system complexity while maintaining the ability to control individual nozzle opening timing and pressure
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 solution effectively delays the opening of nozzles, reducing or eliminating flow front markings and improving melt flow consistency, even with gaseous pressure mediums, thereby enhancing the quality of injection molded components.
Implementation Method 1
A check throttle valve with an adjustable throttle and non-return valve is inserted into the pressure medium line to control the opening of nozzles, slowing down the injection pressure
Implementation Method 2
A check throttle valve with an adjustable throttle and non-return valve is inserted into the pressure medium line
Implementation Method 3
the use of a gaseous pressure medium in piston-cylinder drives for needle shut-off nozzles
Data Source
Figure 1~2
Figure 3~5
AI summary
The method involves injecting a melt at a feed orifice using needle valve-controlled needle valve nozzles into a cavity of a molding tool. The needle valve nozzles are opened at different times for controlling opening speed of the needle valve nozzles and injection pressure at the feed orifice, via corresponding piston-cylinder drives (10) for the needle valve nozzles. A pressurizing medium discharge from the piston cylinder drives is throttled for one of the piston-cylinder drives when the needle valve nozzles are opened. An independent claim is also included for a device for performing a method for cascade injection molding of injection-molded articles.