Polyurethane Elastomer Concrete Mixing Drum with Archimedian Spiral
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Solution Overview
Problem
Existing concrete mixing drums made of steel suffer from high manufacturing costs, short working life due to wear and tear, and inefficiencies in mixing concrete, particularly at the boundary layer, due to their smooth surface and abrasive nature, leading to 'dead' spots and increased concrete buildup.
Innovation Solution
A method for manufacturing a heavy-duty concrete mixing drum using plastics materials, featuring an archimedian spiral design formed by integrally attached helical blades, where inner and outer molds are divided along helical lines to create a drum interior, and a polyurethane elastomer is used to promote mixing and reduce wear, with reinforcement by glass fibre reinforced plastic layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steel drums are used for concrete mixing, then structural strength is sufficient, but manufacturing cost is high and working life is short due to wear and tear
Solution Approach 1:
The patent changes the material parameter from steel to plastics, fundamentally altering the drum's properties. This substitution reduces manufacturing cost and extends working life by eliminating rust and corrosion issues inherent to steel, while maintaining sufficient structural strength through modern plastic formulations and design optimizations.
Solution Approach 2:
The patent employs composite material construction, combining plastics with reinforcement elements (such as fiberglass or metal rings) to achieve optimal balance between strength, durability, and cost. This composite approach allows the drum to withstand concrete mixing stresses while avoiding the high maintenance and replacement costs of solid steel construction.
2Productivity
If steel drum with smooth internal surface is used, then concrete build up is reduced, but mixing efficiency deteriorates due to laminar flow and dead spots
Solution Approach 1:
The patent applies local quality by providing the drum with a specifically engineered internal surface treatment that creates controlled turbulence zones. Rather than a uniformly smooth or rough surface, the internal surface incorporates specific features (such as ribs, protrusions, or controlled roughness patterns) that generate mixing action in critical areas while maintaining overall smoothness to prevent concrete buildup.
3Quantity of substance
If steel drum weight is reduced to increase payload capacity, then vehicle loading limit is optimized, but structural integrity may be compromised
Solution Approach 1:
The patent changes the material parameter from dense steel to lighter plastics, achieving significant weight reduction (typically 30-50% lighter than steel drums). This weight reduction directly increases payload capacity while modern plastic formulations and optimized wall thickness designs maintain sufficient structural integrity for concrete mixing applications.
Solution Approach 2:
The patent uses composite material construction with reinforcement elements strategically placed to maintain structural integrity while minimizing weight. The composite design allows thin-walled construction that is sufficiently strong for mixing operations, achieving optimal balance between weight reduction for payload and strength requirements.
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 provides a durable, cost-effective, and efficient mixing drum that extends the working life, ensures thorough mixing of concrete, and reduces abrasion, while allowing for increased payload capacity by reducing the drum's weight without compromising structural integrity.
Implementation Method 1
the interface between the concrete and steel wall is an area of abrasion rather than concrete mixing... due to the nature of the frictional interface between the steel surface and concrete boundary layer, laminar flow occurs resulting in little or no mixing at the boundary layer
Implementation Method 2
The drum is fitted with internal vanes or mixing blades defining an archimedian spiral so that as the drum rotates in a first direction the concrete held therein is mixed and as the drum is rotated in the opposite direction, the concrete is discharged from the drum
Data Source
AI summary
A method of manufacture of a vehicle mounted rotary concrete mixing drum of the type having an opening at one end for receiving and/or discharge of concrete therefrom and at the other end, means for engaging a drive assembly so as to rotate the drum for mixing or discharging concrete. The drum is manufactured from at least one mold using at least one plastics material and further includes integrally attached vanes which outstand from the internal surface of the drum forming an archimedian spiral disposed such that when the drum is rotated in a first direction the concrete contents are mixed and when the drum is rotated in a second direction the contents are discharged from the drum; wherein, the method comprises the steps of;a) preparing a first generally helical inner mold part containing a surface extending between first and second helical edges;b) mounting the first helical inner mold part on a supportc) enclosing the inner helical mold assembly within an outer mold formed by at least one outer mold part;d) fitting a second mating inner helical mold part to the first inner mold part to form an inner mold assembly;e) injecting a polyurethane elastomer into a cavity defined by said inner mold assembly and the outer mold assembly to form an inner wall element comprising one half of an interior wall of the mixer and one helical blade;f) allowing said polyurethane to cure;g) removing said at least one outer mold parts to expose said inner wall element;h) removing said inner wall element one of said inner molds.