Extruder Screw Segment Wedge Profile Torque Load
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Solution Overview
Problem
Extruder screws face limitations in torque absorption, leading to damage and reduced throughput, as existing designs concentrate peak loads on end faces, causing micro-notches and potential cracks.
Innovation Solution
A prismatic mandrel with external teeth and extruder segments featuring internal teeth with a wedge-shaped gap at the end faces, where the internal toothing is locally weakened to enhance wear resistance, allowing for higher torque absorption without altering the rest of the extruder design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional prismatic mandrel with external teeth and extruder segments with internal teeth is used, then the extruder can operate with high torque, but peak loads occur directly on the end face of the extruder segments, leading to micro-notches and potential cracks
Solution Approach 1:
The internal toothing of the extruder segment is modified locally at the end face area by creating an approximately wedge-shaped space between the flanks of the inner and outer teeth. This local modification redistributes the load away from the critical end face region, preventing micro-notch formation while maintaining overall torque transmission capability. The curvature of tooth flanks in the intermediate space area further softens the load distribution.
2Reliability
If the internal toothing is locally weakened by creating wedge-shaped spaces, then wear resistance is improved, but the structural integrity of the extruder segment may be compromised
Solution Approach 1:
The geometry of the internal toothing is modified by changing the parameters of the tooth profile in the end face area. The wedge-shaped spaces create a gradual transition in material distribution, and the curved tooth flanks provide a smooth stress distribution. These parameter changes locally reduce stress concentration while maintaining sufficient structural integrity through the overall tooth geometry and material properties.
Data Source
Figure 1a
Figure 1b
Figure 1c~1d
AI summary
The invention relates to an extruder screw comprising an extruder shaft and at least one extruder segment (10). The extruder shaft comprises a prismatic mandrel having external teeth and a longitudinal mandrel axis. The extruder segment (10) has internal teeth (12) and a longitudinal internal-teeth axis (L12) and can be slid onto the mandrel, such that the extruder segment (10) can be connected to the mandrel for rotation therewith. The internal teeth (12) have a profile having a meshing profile and, in an inner area between the first (16) and second (18) end faces of the extruder segment (10), comprise a prismatic main profile that has a main cross-section. Furthermore, the internal teeth (12) of the extruder segment (10) have an edge profile adjacent to at least one end face (16) of the extruder segment (10), which edge profile has a smaller edge cross-section than the main profile at least in the area of the meshing profile.