Drop-Shaped Mixing Elements for Injection Moulding

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Solution Overview

Problem

Existing injection molding machines cause significant reduction in fiber length and increased wear when processing highly filled melts, leading to mechanical weaknesses and contamination from metallic dust.

Innovation Solution

A mixing part with a cylindrical base body and drop-shaped mixing elements that co-rotate with the screw, reducing fiber breakage and wear by minimizing the force on the polymer melt and maintaining longer fiber lengths, while the smooth surface of the worm shaft in the backflow stop prevents excessive comminution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If traditional mixing elements with open mixing chambers and convexly rounded edges are used, then mixing effect is improved, but fiber length is significantly reduced

Engineering Contradiction:

Improvemixing effectVSAvoidfiber length

Core Design Contradiction:

Stability of the object's compositionVSLength of moving object

Solution Approach 1:

The mixing elements are designed with drop-shaped geometry featuring streamlined curved surfaces instead of convexly rounded edges. This spheroidal form reduces flow resistance and minimizes mechanical stress on fibers during mixing, maintaining fiber length while achieving effective mixing through the curved flow paths.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention changes the geometric parameters of mixing elements from traditional convexly rounded edges to drop-shaped forms with specific height-to-width ratios. This parameter optimization reduces the force coefficient by up to 95%, significantly decreasing fiber breakage while maintaining mixing effectiveness.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If highly filled melts are processed with traditional mixing elements, then production capacity is maintained, but wear on mixing elements increases significantly

Engineering Contradiction:

Improveproduction capacityVSAvoidservice life of mixing elements

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The invention replaces traditional mechanical mixing elements with metallic or ceramic components with streamlined drop-shaped geometry that reduces mechanical stress concentration. This substitution minimizes wear mechanisms while maintaining mixing capability, extending service life when processing highly filled melts.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Stability of the object's composition

If traditional mixing geometries are used, then mixing function is achieved, but force on polymer melt is high causing fiber breakage

Engineering Contradiction:

Improvemixing functionVSAvoidforce on polymer melt

Core Design Contradiction:

Stability of the object's compositionVSForce

Solution Approach 1:

The drop-shaped mixing elements with streamlined curved surfaces reduce flow resistance and minimize turbulent stress on the polymer melt. The curved geometry distributes force more evenly, reducing peak stresses that cause fiber breakage while maintaining effective mixing function.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

By optimizing the height and width parameters of the drop-shaped mixing elements, the force coefficient acting on the polymer melt is reduced by up to 95%. This parameter optimization maintains mixing effectiveness while significantly decreasing fiber breakage.

Inventive Principle:

Principle #35Parameter changes

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

Significantly reduces fiber breakage and wear, resulting in longer fibers and improved mechanical properties of the plastic molding with reduced contamination from metallic dust.

Implementation Method 1

The melt is divided and recombined by means of the streamlined drop shape. Due to the low resistance coefficient of this shape, the force acting on the polymer melt is reduced by up to 95%

Methodology Applied

Scientific EffectStreamlined flow: Laminar Flow

Implementation Method 2

a mixing part 12 that is connected with the screw 5 in a rotationally fixed manner and co-rotates with the latter is provided downstream from the backflow stop 11

Methodology Applied

Scientific EffectCo-rotation:

Data Source

PatentUS11123906B2Injection moulding machine for producing fibre-reinforced plastic mouldings

Publication Date: 2021.09.21 KRAUSSMAFFEI TECHNOLOGIES GMBH

AI summary

An injection moulding machine for producing fibre-reinforced plastic mouldings, having a closing unit and an injection unit, wherein the injection unit has a cylinder and a screw that can be rotated and displaced in the longitudinal direction in the cylinder, the screw having a backflow stop. In the cylinder, filling openings are provided for feeding in a plastic material to be melted and fibre material. To reduce fibre breakage and ensure good mixing, according to the invention a mixing part is provided downstream and/or upstream of the backflow stop, the mixing part being connected to the screw in a rotationally fixed manner for conjoint rotation therewith and having a cylindrical main body with drop-shaped mixing elements arranged thereon.