Mixing Tool Shaft Coupling Without Threads for Clean Tool Changes
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Solution Overview
Problem
Existing industrial mixing machines face challenges with contamination and thread seizure issues when changing mixing tools, leading to inefficient cleaning and potential tool detachment during the mixing process.
Innovation Solution
A mixing machine design featuring a non-rotationally symmetrical cross-sectional geometry for the tool shaft connection and drive shaft coupling parts, allowing for a torque-locking engagement without internal threads, and a locking device to secure the connection, enabling easy tool change and prevention of contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a threaded connection is used to connect the tool shaft to the drive shaft, then the connection provides torque-locking capability, but the threads become contaminated with mixed material and are difficult to clean
Solution Approach 1:
The connection interface is segmented into external splines on the tool shaft and internal splines on the drive shaft, replacing the threaded structure. This segmentation allows the connection surfaces to be easily accessible and cleanable, eliminating the contamination trapped in thread crevices while maintaining torque transmission capability through the splined engagement.
Solution Approach 2:
Instead of using an internal thread structure that traps contaminants, the patent inverts the approach by using external splines on the tool shaft that engage with internal splines in the drive shaft. This inversion makes the connection surfaces exposed and accessible for cleaning, while still providing the necessary torque-locking function.
2Ease of operation
If the mixing tool is unscrewed from the mix against the direction of rotation, then the tool can be removed, but the threaded sections may come loose and cause accidental release
Solution Approach 1:
The splined connection features asymmetric keyways and locking elements that prevent reverse rotation and accidental disengagement. The asymmetry ensures that the tool shaft can be easily removed in the intended direction while being locked against unintended movement, providing both ease of operation and connection stability.
Solution Approach 2:
A locking mechanism acts as an intermediary between the splined connection elements, providing positive engagement and preventing accidental release. This intermediary component ensures that the tool shaft remains securely connected during operation while allowing intentional removal when needed.
3Reliability
If the tool shaft connection is located within the mixing container, then the connection is protected, but the entire inside of the mixing head must be cleaned when changing tools
Solution Approach 1:
The tool shaft connection is extracted from the interior of the mixing container and positioned at the opening where the mixing head interfaces with the container. This extraction allows the connection to be made and broken outside the container, eliminating the need to clean the entire mixing head interior while changing tools, thus reducing cleaning time while maintaining connection protection.
4Adaptability or versatility
If a detachable connection is used to allow tool changing, then different mixing tools can be used, but the threaded connection may seize up due to material contamination
Solution Approach 1:
The connection is segmented into splined surfaces that provide multiple engagement points around the circumference. This segmentation distributes the load and prevents material from seizing a single thread path, maintaining reliable engagement while allowing easy tool interchangeability. The splined structure can be cleanly separated and re-engaged without material contamination issues.
Data Source
Figure 1
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AI summary
An industrial mixing machine 1 for mixing a powdery or granular material is described, comprising a mixing head 23 for closing the upper opening of a container 2 containing the material to be mixed, which mixing head 23 includes a drive unit 6 and a drive shaft 14, rotatably driven by the drive unit 6 and passing through the mixing head 23, for driving a mixing tool 15 having a tool shaft 27, wherein the tool shaft 27 is detachably connected to the drive shaft 14 by means of a connection mechanism in a torque-locking manner for transmitting a rotational movement of the drive shaft 14 to the tool shaft 27.A special feature of this mixing machine 1 is that the drive shaft 14, as a coupling part, has a tool shaft connection 26 extending through the mixing head 23, into or onto which the tool shaft 27 can be inserted or attached by means of a translational movement by means of its coupling part which is complementary to the tool shaft connection 26 of the drive shaft 14, wherein the two complementary coupling parts have a non-rotationally symmetrical cross-sectional geometry for torque-locking engagement, and that the tool shaft connection 26 on the drive unit side of the mixing head 23 includes a locking device 29 for locking the coupling part of the tool shaft 27 which is engaged with the tool shaft connection 26 of the drive shaft 14.