Extrusion Head Axial Segmentation for Wall Thickness Control
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Solution Overview
Problem
Existing extruder heads for blow-molding are complex and expensive, requiring dynamic radial wall thickness control systems with additional actuators and special software to vary tube wall thickness uniformly over the circumference, which is not cost-effective and introduces technical complexities.
Innovation Solution
The extruder head design features at least one head part with multiple sections of uniform cross-sectional areas, allowing axial displacement to vary the flow channel geometry and wall thickness, with transitional sections for continuous surface transitions, and an optional elastic tilt joint in the nozzle for further geometry alteration, enabling dynamic axial and radial wall thickness control without complex actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dynamic radial wall thickness control systems with actuators are used, then wall thickness distribution is improved, but device complexity and cost increase
Solution Approach 1:
The extruder head is divided into multiple sections (first section, second section, third section) along the flow channel, each with different cross-sectional areas. This segmentation allows different wall thicknesses to be produced in different sections without requiring complex control systems or actuators.
Solution Approach 2:
Instead of controlling wall thickness radially (circumferential direction) through actuators, the invention controls it axially (length direction) by varying the cross-sectional area of different sections along the flow channel. This dimensional shift eliminates the need for complex radial control mechanisms.
2Device complexity
If fixed extruder head geometry is used, then device complexity is reduced, but wall thickness distribution becomes uniform and cannot meet complex molded body requirements
Solution Approach 1:
Different sections of the extruder head are designed with different cross-sectional areas tailored to specific requirements. The first section has a larger area for thicker walls, the second section has a smaller area for thinner walls, and the third section transitions between them. This local differentiation achieves complex thickness distributions while maintaining structural simplicity.
3Manufacturing precision
If conical discharge region with tapered head parts is used, then wall thickness can be varied in draw-off direction, but wall thickness control over circumference becomes complex
Solution Approach 1:
The discharge region is divided into multiple axial sections with different cross-sectional areas. Each section can be independently designed to produce specific wall thickness patterns, eliminating the need for complex circumferential control mechanisms while maintaining the ability to vary thickness in the draw-off direction.
Data Source
AI summary
The invention relates to an extrusion head and a method with which the thickness distribution of hollow bodies, for example, can be further improved. The extrusion head consists of at least one mandrel (1) and one nozzle (2), which have a rigid geometry and therefore cannot be varied or can also be deformed flexibly in some areas and form a flow channel (3), wherein the positions of the mandrel (1) and the nozzle (2) can be varied relative to one another, so that the geometry of a discharge gap (s) of the flow channel (3) can be varied while a melt is being discharged, wherein each head part has at least one head section with a uniform cross-sectional area in a discharge area (A) of the extrusion head, and wherein at least one head part has at least two head sections (B) and (C), each of which has a predominantly uniform cross-sectional area within the head section (B), (C), which are spaced axially apart from one another and which have mutually different cross-sectional areas.