Hand Tool Clamping Device Run-Off Safety Unit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Handheld power tool clamping devices, such as those for angle grinders, face issues with tools running off the spindle during braking operations due to relative movements caused by mass moments of inertia, leading to loose clamping and potential detachment.
Innovation Solution
The integration of a run-off safety unit that converts first relative movements between fastening elements into second relative movements, combined with a decoupling unit to reduce clamping force and a resetting unit for automatic return to a basic position, ensures secure tool attachment and prevents detachment during braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fastening unit is used to secure a tool on a spindle, then the tool can be firmly clamped during operation, but the tool may run off the spindle during braking due to relative movement caused by mass moments of inertia
Solution Approach 1:
The fastening unit incorporates a dynamic run-off protection mechanism that automatically activates during braking. The protection unit includes movable protection elements that can shift position in response to relative movement between the tool and spindle, converting harmful relative motion into a protective clamping action that prevents tool run-off.
Solution Approach 2:
The run-off protection unit is pre-configured to counteract the harmful effects of braking-induced relative movement before the tool can run off. The protection elements are positioned and dimensioned to engage and prevent tool run-off as soon as relative movement occurs, effectively neutralizing the harmful effect in advance.
2Reliability
If the clamping force is increased to prevent tool run-off, then tool security during braking improves, but the difficulty of tool detachment increases
Solution Approach 1:
The fastening unit features a decoupling mechanism that dynamically reduces clamping force when detachment is initiated. The decoupling unit includes movable elements that, when actuated, reduce the clamping force exerted by the fastening elements on the tool, enabling easy tool removal while maintaining high clamping force during normal operation and braking.
Solution Approach 2:
The fastening unit is divided into separate functional segments: a fastening unit for securing the tool, a run-off protection unit for preventing tool run-off, and a decoupling unit for facilitating tool removal. This segmentation allows each unit to perform its specific function independently, maintaining strong clamping during operation while enabling easy detachment when needed.
3Reliability
If a run-off protection unit is added to prevent tool run-off during braking, then tool security improves, but the device complexity increases
Solution Approach 1:
The run-off protection unit is integrated into the existing fastening unit structure, combining multiple functions (fastening, run-off protection, and decoupling) into a single unified device. The protection elements are incorporated as part of the fastening unit assembly, sharing common components such as the body, fastening elements, and actuation mechanisms, thereby minimizing additional complexity while maximizing protective functionality.
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
The solution effectively prevents tools from running off the spindle and ensures reliable operation by maintaining or increasing clamping force during braking, while allowing easy decoupling and reattachment without tools, enhancing both safety and convenience.
Implementation Method 1
designed to at least partially convert a first relative movement between at least two fastening elements of the clamping unit into a second relative movement
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a chucking device for a hand machine tool having at least one fastening unit (12a; 12b; 12c) for securing a tool (14a; 14b; 14c) in the axial direction (16a; 16b; 16c) on a spindle (18a; 18b; 18c), and having at least one decoupling unit (20a; 20b; 20c) for decoupling at least one fastening element (22a; 22b; 22c) of the fastening unit (12a; 12b; 12c) in the axial direction (16a; 16b; 16c). According to the invention, the chucking device for the hand machine tool comprises a runoff safety unit (26a; 26b; 26c) for at least partially transferring a first relative motion between at least two fastening elements (22a, 28a; 22b, 28b; 22c, 28c) of the fastening unit (12a; 12b; 12c) into a second relative motion for preventing runoff of the fastening unit (12a; 12b; 12c) and/or the tool (14a; 14b; 14c) from the spindle (18a; 18b; 18c) in a braking mode.