Twin-Screw Extruder Safety Coupling for High-Torque Compact Drives

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Solution Overview

Problem

Twin-screw extruders face challenges with existing safety clutches due to space constraints and material limitations, leading to increased costs and potential damage from overloading, as they require additional intermediate shafts and complex production processes to accommodate higher torques and precise stress calculations.

Innovation Solution

Integrating coupling bushings directly into the shaft ends of twin-screw extruder and transmission output shafts, eliminating the need for separate coupling bushings and internal gearing, and using cylindrical pins and intermediate elements to distribute torque, allowing for a more precise and cost-effective safety clutch design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If separate coupling bushings with internal gearing are used, then torque transmission is achieved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvetorque transmissionVSAvoidcoupling structure complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent merges the coupling bushing function directly into the shaft end design. The shaft end itself is configured with a shaft shoulder that accommodates shearing elements, eliminating the need for separate coupling bushings with internal gearing. This integration simplifies the overall structure while maintaining torque transmission capability through the shearing elements positioned at the shaft end parting line.

Inventive Principle:
Principle #5Merging (Combining)

2Power

If safety clutches are arranged next to each other with increased torque, then higher power transmission is achieved, but space requirements increase requiring intermediate shafts

Engineering Contradiction:
Improvetorque capacityVSAvoidaxial space requirement
Core Design Contradiction:
PowerVSLength of stationary object

Solution Approach 1:

The patent optimizes the radial arrangement of shearing elements at the shaft end, utilizing the circular perimeter area efficiently. By positioning multiple shearing elements around the parting line in a radial pattern, the design achieves higher torque capacity without increasing axial length, allowing safety clutches to be arranged adjacently without intermediate shafts.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of operation

If shaft ends with notches and internal gearing are used, then coupling function is achieved, but manufacturing precision and material homogeneity decrease

Engineering Contradiction:
Improvecoupling functionalityVSAvoidshaft end homogeneity
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent extracts the gearing function from the shaft end design, eliminating notches and internal teeth. The shaft end remains homogeneous without discontinuities, and the coupling function is achieved purely through the shearing elements that bridge the parting line between shafts, maintaining material continuity and manufacturing precision.

Inventive Principle:
Principle #2Taking out (Extraction)

4Power

If intermediate shafts are provided for safety clutches, then torque distribution is improved, but device complexity and production difficulty increase

Engineering Contradiction:
Improvetorque distributionVSAvoidproduction simplicity
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

The shaft end design serves multiple functions simultaneously: it provides structural support, accommodates shearing elements for torque transmission, and enables safety clutch functionality without requiring separate intermediate shafts. This multi-functionality simplifies the overall drivetrain architecture while maintaining effective torque distribution.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 simplifies the design, reduces costs, enhances static and dynamic strength, and allows for precise torque control, minimizing the risk of damage and downtime while accommodating higher torques within the given center distance without the need for additional shafts or complex production steps.

Implementation Method 1

the shear stress per shear pin can be calculated well

Methodology Applied
Scientific EffectShear stress: Shear Stress

Data Source

PatentEP3815875B1Twin screw extruder with integrated safety couplings
Publication Date: 2022.03.09 VEKA AG
  • EP3815875B1 patent drawingFigure 1
  • EP3815875B1 patent drawingFigure 2
  • EP3815875B1 patent drawingFigure 3

AI summary

Twin-screw extruder (100') with integrated safety couplings, comprising at least a pair of extruder screw shafts, each with a drive-side shaft end (10), and a gearbox with two drive shafts, each with a shaft end (20), wherein one extruder screw shaft and one drive shaft are arranged in alignment on a common central axis; characterized in that the pair of shaft ends (10) of the extruder screw shafts and/or the pair of shaft ends (20) of the gearbox is cylindrical;- that on the end faces (15) of at least one pair of shaft ends (10, 20) several bores (14) parallel to the central axis are provided for at least two pin-shaped shear elements (32), and - the shaft ends (10, 20) are torque-stiffenedly coupled to each other via the shear elements (32) inserted into the bores (14), which bridge at least the parting plane formed between the shaft ends (10) of the extruder screw shafts and the shaft ends (20) of the gearbox.;