Stuffing Screw Housing Recesses for Rubber Extruder Degassing
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Solution Overview
Problem
Existing stuffing screws in extruder systems face challenges in reducing the discharge of product particles during degassing, particularly with high viscosity elastic materials like rubber, due to high gas velocities causing particles to be thrown back and not adhere to the screw's profile flanks, leading to clogging and efficiency losses.
Innovation Solution
The design of a stuffing screw with recesses or grooves in its housing creates stagnation zones with low gas speed, allowing product particles to deposit and agglomerate, which can then be safely returned to the extruder system, reducing particle discharge and preventing clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conventional stuffing screw is used for degassing, then gas can be removed from the extruder, but product particles are thrown back by high gas velocities and discharged over the stuffing screw
Solution Approach 1:
The housing inlet is segmented into multiple recesses distributed across the surface. These recesses divide the continuous high-velocity gas flow into multiple smaller zones, reducing the velocity and kinetic energy of the gas in each zone. This allows product particles to deposit in the recesses rather than being thrown back by a single large high-velocity flow.
Solution Approach 2:
The recesses create localized zones with different flow characteristics - low velocity and high turbulence - specifically at the housing inlet where particle deposition is needed. The rest of the stuffing screw maintains its original high-velocity gas removal function. This local modification addresses the particle discharge problem without compromising the overall degassing efficiency.
2Productivity
If high gas velocities are used for vapor removal, then degassing efficiency is improved, but product particles cannot adhere to the screw profile flanks and are thrown back
Solution Approach 1:
The recesses are positioned at the housing inlet to intercept product particles before they can be thrown back by the high-velocity gas flow. The recesses provide a preliminary deposition zone where particles can settle out of the vapor stream before the gas continues its path through the stuffing screw, preventing the adhesion problem entirely.
Solution Approach 2:
The high gas velocity, which normally causes harmful particle throw-back, is redirected into the recesses where it creates beneficial turbulent mixing and enhanced particle-collision opportunities. The kinetic energy that would otherwise eject particles is now used to promote particle deposition and agglomeration within the recesses.
3Object-generated harmful factors
If recesses are added to the housing inlet, then particle deposition is improved, but device complexity increases
Solution Approach 1:
The recesses create a porous-like structure on the housing inlet surface, providing numerous small cavities for particle deposition. This approach achieves effective particle capture without requiring a complex filter or separator, maintaining relative structural simplicity while improving particle retention.
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 effectively reduces the discharge of product particles, preventing clogging and protecting downstream equipment by allowing agglomerated particles to be safely managed within the extruder system, enhancing the efficiency of the degassing process and material handling.
Implementation Method 1
The recesses ensure that at the housing inlet stagnation zones with low gas speed. In these stagnation zones, the speed of the product-related product particles decreases, allowing a deposition in the groove.
Implementation Method 2
the speed of the product-related product particles decreases, allowing a deposition in the groove
Implementation Method 3
The recesses also have the advantage that the product particles can agglomerate therein. The agglomerates are then no longer torn by the gas flow
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
A stuffing screw (2) for use in an extruder system comprises a housing (7) and at least one screw conveyor (5) mounted rotatably inside the housing (7), wherein a conveying space is formed between an inner side of the housing (7) and the screw conveyor (5). The stuffing screw (2) is characterized in that the inner side of the housing (7) is provided, at least in one section, with one or more depressions, in particular in the form of a groove (13).