Melt Pump with Interlocking Screw Conveyors for Extrusion
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Solution Overview
Problem
Existing methods for producing plastic granules, extruded profiles, or molded parts require pressure-increasing units like gear pumps or single-screw pumps, which lead to pulsation, high energy consumption, and equipment complexity, resulting in inefficient and costly processes due to frictional heat and suboptimal component design.
Innovation Solution
A method that eliminates the need for a pressure-increasing unit by using a melt pump with interlocking screw conveyors and a housing design that creates a gap seal, allowing for forced conveyance of the plastic melt without significant backflow, enabling high pressure build-up and efficient energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a gear pump or single-screw pump with its own drive is used to transfer plastic melt, then pressure can be increased, but pulsation occurs and pre-pressure builds up at the pump inlet
Solution Approach 1:
The patent merges the pressure increase function directly into the screw machine by adding one or two pressure-increasing screw elements to the existing screw shaft, eliminating the need for a separate gear pump or single-screw pump. This integration removes the interface between two separate pumping systems that causes pulsation, while achieving the required pressure buildup for extrusion or injection molding.
Solution Approach 2:
The screw machine is designed to perform multiple functions: mixing, kneading, conveying, and pressure increase. By incorporating pressure-increasing screw elements into the universal screw shaft, the system eliminates the need for dedicated pressure-increasing equipment, reducing overall system complexity and eliminating pulsation issues associated with separate pump drives.
2Stress or pressure
If an integrated gear pump or screw elements causing pressure increase are added to the screw machine, then pressure build-up is achieved, but the drive must be much more powerful and equipment complexity increases
Solution Approach 1:
The pressure increase function is merged into the existing screw machine structure by adding screw elements directly to the screw shaft. This eliminates the need for separate gear pumps, multiple screw shafts, or additional drives, thereby reducing equipment complexity while achieving the required pressure buildup.
Solution Approach 2:
The screw machine is designed as a multi-functional device that performs mixing, kneading, conveying, and pressure increase through its screw elements. This universal design eliminates the need for separate pressure-increasing equipment, reducing overall system complexity and the number of components required.
3Stability of the object's composition
If high speed is used in the screw machine for homogeneous plastic melt, then mixing efficiency is improved, but friction increases resulting in high energy consumption and heat development
Solution Approach 1:
The screw shaft is divided into distinct functional zones: mixing/kneading sections with high friction for homogeneous melt, and pressure-increasing screw elements with reduced friction. This segmentation allows high-speed operation in the mixing zone while minimizing energy consumption in the pressure increase zone, where the gap seal reduces frictional losses.
Solution Approach 2:
Different sections of the screw shaft have different local characteristics: the mixing sections have high friction for thorough blending, while the pressure-increasing sections have reduced friction through gap seal design. This local quality optimization allows high-speed operation to achieve homogeneous melt without excessive overall energy consumption.
4Stress or pressure
If a pressure-increasing unit is integrated into the screw machine, then pressure can be increased, but the screw machine requires a much more powerful drive and reinforced components
Solution Approach 1:
The pressure increase function is merged into the existing screw machine by adding screw elements to the current screw shaft. This integration allows the existing drive to handle pressure increase as part of its multi-functional role, avoiding the need for a much more powerful dedicated pressure-increasing drive.
Solution Approach 2:
The screw machine is designed as a universal device performing mixing, kneading, conveying, and pressure increase. The existing drive is optimized to handle all these functions efficiently, eliminating the need for additional powerful drives that would be required if pressure increase were handled by separate dedicated equipment.
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 approach reduces pulsation, energy consumption, and equipment costs by allowing the screw machine to operate with a smaller drive, achieving high pressures without the need for a pressure-increasing device, and prevents thermal damage to the plastic melt.
Implementation Method 1
The screw webs of the two screw conveyors interlock in such a way that the screw gap remaining at the narrowest point forms a gap seal and at the same time the housing is designed in such a way that the housing gap remaining between the housing and the screw conveyors also forms a gap seal
Implementation Method 2
two screw conveyors (8) rotating in opposite directions, wherein the screw flight (9) of one screw conveyor (8) engages in the screw flight (9) of the other screw conveyor (8) in such a way that the plastic melt is forced to be conveyed
Data Source
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AI summary
The invention concerns a device for producing polymer pellets, extruded profiles or mouldings, comprising an extruder for producing a polymer melt, comprising a melt pump (2) for building up pressure for the purpose of forcing the polymer melt through a die and comprising the die for creating the pellet, the extruded profile or the moulding, wherein the melt pump (2) is formed separately from the extruder and has a drive (5) of its own. Providing such a device for producing polymer pellets, extruded profiles or mouldings in which the extruder does not need a pressure increasing unit is achieved by the transfer of the polymer melt from the extruder to the melt pump (2) taking place in a pressureless or almost pressureless manner.