Dosing Valve for Additive Manufacturing Powder Control
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Solution Overview
Problem
During the manufacture of large three-dimensional products, the use of large powder quantities in a build chamber under vacuum conditions leads to uncontrolled powder movement and inaccurate dosing due to air extraction, causing powder to be deposited inaccurately on the build surface.
Innovation Solution
A dosing valve system is implemented in the hopper, which moves laterally across the dosing opening, creating varying volumes on either side to control powder flow, and a bleed channel is used to evacuate air, ensuring accurate dosing and preventing uncontrolled powder movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large powder quantities are used in the hopper to manufacture large three-dimensional products, then the productivity and manufacturing capability are improved, but the powder behaves uncontrollably due to air extraction during vacuum creation, causing inaccurate dosing
Solution Approach 1:
The hopper bottom is segmented into multiple dosing openings (first dosing opening and second dosing opening) instead of a single opening. This segmentation allows the powder mass to be divided into separate dosing zones, preventing uncontrolled movement while maintaining the ability to dose large quantities of powder for large three-dimensional products.
Solution Approach 2:
A dosing valve is introduced as an intermediary element that extends across both dosing openings. This dosing valve acts as a mediator between the powder mass and the build chamber, controlling powder flow through its lateral movement to cover or uncover the dosing openings. The dosing valve prevents direct uncontrolled access of powder to the vacuum environment while enabling precise dosing.
2Reliability
If the build chamber is placed under vacuum to create modified atmosphere, then the product quality is improved, but air extraction from powder causes uncontrolled powder movement and boiling behavior
Solution Approach 1:
The dosing valve is positioned to cover the dosing openings before vacuum is applied to the build chamber. This preliminary action prevents air from being extracted from the powder mass at the dosing interface, avoiding the boiling and uncontrolled movement that would otherwise occur during vacuum creation. The dosing valve is already in place to seal the powder from the vacuum environment.
Solution Approach 2:
The dosing valve serves as a protective intermediary between the powder and the vacuum environment. It prevents direct exposure of the powder to pressure changes, thereby maintaining powder stability during vacuum creation while still allowing the build chamber to be placed under vacuum for product quality.
3Use of energy by stationary object
If powder is drawn along the dosing opening due to pressure drop, then vacuum efficiency is improved, but powder is deposited inaccurately on the build surface
Solution Approach 1:
The dosing valve acts as a selective intermediary that controls which powder reaches the vacuum environment. It allows the vacuum to be applied efficiently to the build chamber while preventing powder from being drawn along the dosing opening. The dosing valve maintains a seal between the powder reservoir and the vacuum zone, eliminating inaccurate powder deposition.
Solution Approach 2:
The dosing valve provides localized control at the dosing openings, allowing different regions of the hopper system to have different pressure conditions. The area around the dosing openings is sealed off from the vacuum when the valve covers them, preventing powder draw-in, while the build chamber maintains efficient vacuum for the actual manufacturing process.
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
The solution enables precise dosing and application of powder layers on the build surface, maintaining uniformity and accuracy even with large powder quantities, thereby improving the manufacturing process for three-dimensional products.
Implementation Method 1
When placing the build chamber under a vacuum in order to create the required modified atmosphere, air is drawn from the powder in the hopper
Implementation Method 2
this results in air being extracted from the powder mass
Implementation Method 3
a measured quantity of powder for the manufacture of said product flows out of the hopper to a powder dispenser
Data Source
AI summary
A device is provided for layered manufacture of at least a three-dimensional product by an additive manufacturing technique based on a powder. The invention therefore relates to a device for the layered manufacturer of a product based on a powder, in particular a metal powder.This device is fitted with a build chamber with a vertically movable build platform on which said product is manufactured and contains a powder dispenser for application of the successive powder layers on the build platform in a horizontal build surface. The powder dispenser can be moved back and forth over the build surface along a horizontal dispensing direction in order to apply said powder layers.Moreover, the device contains a hopper that must contain said powder in order to supply powder to the powder dispenser. This hopper has a bottom with a dosing opening that lets out into the build chamber and that works in combination with a dosing valve. More specifically, the dosing valve enables a measured quantity of powder to flow out of the hopper.