Split-Shaft Plaster Mixer for Selective Wear-Part Replacement
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Solution Overview
Problem
Existing mixers for mixing and spraying mortars and plasters suffer from progressive wear of mixing arms due to abrasive materials, necessitating frequent replacement of the entire mixer, including components not affected by wear, leading to material waste and increased maintenance costs, and placing undue stress on the motorization unit.
Innovation Solution
The mixer is designed with a split shaft comprising two separate parts connected by a joint sleeve and pins, allowing the fork and first part of the shaft to be replaced independently, while the second part of the shaft and helical elements can be reused, and an elastomer gasket absorbs transverse stresses to reduce wear and stress on the motorization unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the mixer uses a single-piece fork and rotation shaft design, then the structure is simple and easy to manufacture, but the entire mixer must be replaced when the mixing arms wear out, leading to material waste and increased costs
Solution Approach 1:
The rotation shaft is divided into two separate parts: a first part that remains fixed in the motorization unit and a second part that is coupled to the fork. This segmentation allows the fork and second part to be replaced independently when worn, while the first part and motorization unit can be reused, thereby reducing material waste while maintaining manufacturing simplicity.
2Device complexity
If the mixer uses a single-piece fork and rotation shaft design, then the device complexity is low, but the replacement of worn mixing arms requires replacing the entire mixer including unaffected components
Solution Approach 1:
The rotation shaft is segmented into a first part (fixed in motorization unit) and a second part (coupled to fork), enabling selective replacement of only the worn components (fork and second part) while retaining the first part and motorization unit, thus improving ease of repair without significantly increasing device complexity.
Solution Approach 2:
The coupling between the first and second parts of the rotation shaft is designed to allow relative movement or separation, enabling dynamic reconfiguration where worn parts can be detached and replaced independently, improving maintainability while keeping the overall structure relatively simple.
3Ease of operation
If the mixer is subjected to oscillating rotation from the screw rotor, then the dispensing function is achieved, but abnormal stress is placed on the motorization unit supports and bearings
Solution Approach 1:
The first part of the rotation shaft acts as an intermediary element between the motorization unit and the fork. It absorbs and isolates the oscillating stresses generated by the screw rotor, preventing these abnormal stresses from being transmitted to the motorization unit supports and bearings, thereby improving reliability while maintaining dispensing functionality.
4Reliability
If the mixing arms undergo progressive wear from abrasive material, then the mixing function degrades over time, but replacing the entire mixer increases maintenance costs
Solution Approach 1:
The rotation shaft is divided into replaceable and non-replaceable parts. The second part coupled to the fork can be replaced when mixing arms wear out, while the first part remains in the motorization unit. This allows selective replacement of only the worn components, reducing maintenance costs while ensuring mixing efficiency is maintained.
Solution Approach 2:
The design enables discarding only the worn fork and second part of the rotation shaft, while recovering and reusing the first part of the rotation shaft and the motorization unit. This selective replacement strategy reduces maintenance costs by avoiding unnecessary replacement of unaffected components.
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 design reduces maintenance costs and extends the lifespan of the mixer by enabling selective replacement of worn parts, maintains mixer efficiency, and minimizes stress on the motorization unit, improving the quality of the composition produced.
Implementation Method 1
an elastomer gasket absorbs transverse stresses to reduce wear and stress on the motorization unit
Implementation Method 2
a helical element M is wound which affects part of the length of the rotation shaft D and part of the length of the fork B and has the function of favouring the conveying of the powdered or granular mixture coming from a loading vessel, along the mixing chamber G
Implementation Method 3
During rotation, the mixer A kneads the powdered or granular mixture with water
Data Source
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AI summary
A mixer (1) for mixing-plastering machines comprising: a fork (2) comprising two arms (3) and an upper bridge (4) connecting them to each other, a shaft (7) projecting from the upper bridge (4) and having an end tab (8) connecting to a motorisation unit for the rotation of the mixer (1), and helical means (9) wound outside the shaft (7) and the arms (3) for at least part of the length of both. The shaft (7) is divided into two separate and distinct parts comprising a first part (10) belonging to the upper bridge (4) and a second part (11) belonging to the end tab (8) which are housed one after the other within a joint sleeve (12) to which they are constrained by a first pin (14) and a second pin (15), respectively. There is a clearance between the first part (10) of the shaft (7) and the joint sleeve (12), which allows the oscillatory movement of the first part (10) of the shaft (7) around the respective first pin (14) during the rotation of the mixer (1).