Machine Tool Switch Logic for Continuous Operation

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Solution Overview

Problem

Existing machine tools, particularly grinders, require continuous actuation of a pressure switch to remain activated, which is problematic in terms of safety and operational convenience.

Innovation Solution

A method involving a control process that uses a combination of an actuation switch and a locking switch, where the actuation switch is activated and then deactivated to set the machine tool to a predetermined speed, and the locking switch is activated within a specified time to maintain continuous operation without permanent pressure, utilizing a common switch device such as a rocker switch.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a push-button switch without latching function is used to activate the machine tool, then the device complexity is reduced, but the ease of operation deteriorates because continuous pressure is required to maintain activation

Engineering Contradiction:
Improveswitch structureVSAvoidcontinuous actuation requirement
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The switching function is segmented into two distinct switches: an actuation switch for temporary activation and a locking switch for permanent activation. This segmentation allows each switch to have a specific function, resolving the contradiction by providing simple switch structures while eliminating the need for continuous actuation through the locking switch capability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically transitions between temporary activation mode (using actuation switch) and permanent activation mode (using locking switch). The control device detects which mode is active and adjusts the switching behavior accordingly, providing ease of operation without requiring continuous actuation while maintaining simple switch structures

Inventive Principle:
Principle #15Dynamics

2Object-affected harmful factors

If the actuation switch is deactivated after a brief press, then safety is improved by preventing accidental permanent activation, but the reliability deteriorates because the machine tool cannot maintain continuous operation

Engineering Contradiction:
Improveunintentional activationVSAvoidcontinuous operation capability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The locking switch is activated within a predetermined time period after the actuation switch is deactivated. This preliminary action sequence allows the system to transition from temporary to permanent activation without requiring continuous pressure on the actuation switch, thereby maintaining reliability while improving safety

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The locking switch acts as an intermediary between the actuation switch and the drive system. It receives the activation signal from the actuation switch and maintains the activation state independently, resolving the contradiction by providing a reliable continuous operation capability while preventing unintentional permanent activation through the two-step process

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If a locking mechanism is added to maintain activation without continuous pressure, then the ease of operation is improved, but the device complexity increases due to additional switching components and control logic

Engineering Contradiction:
Improverelease finger capabilityVSAvoidswitching mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The locking switch serves multiple functions: it can be activated to lock the machine tool in the activated state, and it can also be used to deactivate the machine tool by switching to the deactivated state. This multi-functionality reduces the need for additional components, improving ease of operation while limiting the increase in device complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

Both the actuation switch and locking switch are integrated into a common switch device with a continuous surface. This merging of functions into a single physical component reduces overall device complexity while maintaining the ease of operation benefits by allowing the user to release their finger after activation

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3774178B1Switch for machine tool and switching logic
Publication Date: 2024.05.01 HILTI AG
  • EP3774178B1 patent drawingFigure 1
  • EP3774178B1 patent drawingFigure 2
  • EP3774178B1 patent drawingFigure 3

AI summary

A first aspect of the invention relates to a method for controlling a machine tool, the machine tool comprising a control device, a drive, a tool, an actuation switch and a locking switch. The method comprises the following method steps: - activating the actuation switch by exerting a force in the direction of the actuation switch in order to switch the machine tool from a deactivation mode to an activation mode, therefore setting the drive to a first predefined rotational speed value; - deactivating the actuation switch, therefore stopping the force in the direction on the actuation switch, the drive being set at the first predefined rotational speed value for a predefined period of time; - activating the locking switch within the first predefined period of time after the actuation switch has been deactivated, therefore setting the drive to a predefined second rotational speed value; and - activating the actuation switch by exerting a force in the direction of the actuation switch or activating the locking switch by exerting a force in the direction of the locking switch in order to switch the machine tool from the activation mode to the deactivation mode. A second aspect of the invention relates to a machine tool for performing the method.