Extruder Screw Coupling With Internal Locking for Higher Torque
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Solution Overview
Problem
Existing screw machines face limitations in increasing driving torque due to interference between linkage parts linking screws and output shafts, constrained by the limited space between screws and the need for larger output shaft diameters.
Innovation Solution
A screw machine design featuring a linkage part with a coupling and locking mechanism that includes an insertion hole, fixing part, and a locking part formed of divided pieces, allowing for increased output shaft diameter without interference by restricting relative movement between the screw and output shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the diameter of the output shaft is increased to increase the driving torque of the screw, then the driving torque is improved, but the linkage part size increases and causes interference between the pair of linkage parts
Solution Approach 1:
The locking part is divided into multiple divided pieces (first through fourth divided pieces) arranged circumferentially around the output shaft. This segmentation allows the locking part to fit within the limited space between the pair of screws while still providing effective locking functionality, thus reducing the overall linkage part size and preventing interference between adjacent linkage parts.
Solution Approach 2:
The divided pieces of the locking part are nested within the coupling's insertion hole, which has a larger diameter than the output shaft. The locking part is positioned between the output shaft and the coupling, creating a nested structure that maximizes space utilization and prevents interference while maintaining the required driving torque capability.
2Force
If the diameter of the output shaft is increased to increase the driving torque of the screw, then the driving torque is improved, but the nuts that link the screws and output shafts interfere with each other
Solution Approach 1:
The locking part is extracted from the traditional nut structure and repositioned within the coupling's insertion hole. This removes the interfering nut from the external space between linkage parts and relocates it internally, where it can provide the necessary locking function without causing interference between adjacent linkage parts.
Solution Approach 2:
Instead of using a traditional nut that extends radially outward from the output shaft, the locking part is positioned in the axial dimension within the coupling's insertion hole. This dimensional repositioning eliminates radial interference between adjacent linkage parts while maintaining the locking function in the axial direction.
3Reliability
If a coupling structure with nut is used to link the screw and output shaft, then the linkage is secure, but the linkage part size increases and is limited by space between screws
Solution Approach 1:
The locking part is merged with the coupling structure by positioning it within the coupling's insertion hole. This integration combines the coupling and locking functions into a single compact assembly, maintaining secure linkage between the screw and output shaft while minimizing the overall linkage part size to fit within the space between the pair of screws.
Data Source
AI summary
An extruder has a pair of linkage parts configured to respectively link end portions of a pair of output shafts of the speed reducer with end portions of a pair of screws coaxially. The linkage parts each has: a coupling having an insertion hole into which the end portion of the screw and the end portion of the output shaft are inserted; and a locking part attached to the end portion of the output shaft. The coupling has a first receiving portion configured to receive the end portion of the output shaft; the second receiving portion configured to receive the locking part; and a step portion formed between the first receiving portion and the second receiving portion. As the step portion is locked by the locking part, a relative movement of the coupling relative to the output shaft in a direction towards the screw is restricted.