Electrically Isolated Spindle Locking for Safe Tool Changes
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Solution Overview
Problem
Machine tools, such as drywall milling machines, pose a risk of electric shock to operators when changing tools, as the conductive locking device can become electrically charged and bypass the insulating spindle bearings, potentially leading to contact with live lines.
Innovation Solution
The locking device is equipped with an electrically insulating bearing device and actuating element, made of materials like plastic or coated with insulating materials, to prevent electrical discharge and ensure operator safety during tool changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the locking element is made of metal for stability, then the mechanical strength and stability are improved, but the electrical conductivity increases causing risk of electric shock to the operator
Solution Approach 1:
The patent introduces an electrically insulating bearing device as an intermediary component between the locking element and the machine tool housing. This mediator allows the metal locking element to maintain its mechanical stability while preventing electrical conduction to the housing and operator, thus resolving the contradiction between strength and electrical safety
Solution Approach 2:
The locking device is segmented into distinct functional components: the metal locking element for mechanical function and the insulating bearing device for electrical isolation. This segmentation allows each component to optimize its specific function without compromising the other, enabling the locking element to be metal for strength while the bearing device provides electrical insulation
2Object-affected harmful factors
If the spindle is electrically insulated from the housing using insulated bearings, then the operator protection is improved, but the locking mechanism cannot effectively lock the spindle when the tool contacts live wires
Solution Approach 1:
The insulating bearing device acts as a mediator that maintains electrical isolation while allowing mechanical interaction. It enables the locking element to mechanically engage with the spindle for effective locking while preventing electrical conduction, thus maintaining both operator protection and locking reliability simultaneously
3Object-affected harmful factors
If the locking element is surrounded by an electrically insulating coating or casing, then the electrical isolation is improved, but the device complexity increases
Solution Approach 1:
The patent merges the electrical insulation function with the existing bearing structure by providing a bearing device that is integrated into the locking mechanism. This consolidation achieves electrical isolation without adding separate complex insulation components, thus improving electrical safety while minimizing increases in device complexity
Data Source
Figure 1~2
Figure 3~6
AI summary
The invention relates to a machine tool having a tool holder for exchangeably holding a tool, the machine tool comprising: a machine tool housing; a spindle, which is rotatably mounted in the machine tool housing and which has a drive end and an holding end, the drive end being connected to a drive for rotating the spindle about an axis of rotation and the holding end being coupled to the tool holder; and a locking device, which is arranged in the machine tool housing and which has a locking element having a locking end for interacting with the spindle and which has an actuation end, the locking element being reversibly movable between a release position and a locking position, the locking end of the locking element having at least one interlocking connection means and the spindle having at least one mating interlocking connection means, the at least one interlocking connection means of the locking element being disengaged from the at least one mating interlocking connection element of the spindle in the release position of the locking element in order to enable rotational motion of the spindle, and the at least one interlocking connection means of the locking element being engaged with the at least one mating interlocking connection element of the spindle in the locking position of the locking element in order to prevent rotational motion of the spindle and to enable an exchange of the tool of the tool holder, the locking device also comprising an electrically insulating mounting device for mounting the locking element in the machine tool housing in order to electrically insulate the locking element from the machine tool housing.