Portable Grinder Eccentric Drive Oscillating Motion
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Solution Overview
Problem
Portable machine tools, such as grinding machines, face challenges in achieving efficient oscillating motion of tool holders without the use of vibrating elements, while maintaining a compact and lightweight design with sufficient power and battery life.
Innovation Solution
The design incorporates a drive unit with a roller bearing arranged eccentrically to the drive axis, which converts rotational energy into a pendulum movement of the tool holder about a bearing axis, allowing for oscillating motion without oscillating elements, and a radial bearing for rotatable mounting, enabling efficient grinding with a compact and lightweight structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a portable machine tool uses a compact battery-powered drive system, then portability and mobility are improved, but the available power and runtime are limited
Solution Approach 1:
The patent employs an eccentric drive mechanism that converts rotational motion into oscillating motion through an eccentric rolling bearing. This mechanical vibration approach enables the portable grinder to achieve effective grinding action with a compact battery-powered motor, resolving the contradiction between limited battery power and sufficient grinding performance.
2Productivity
If the machine tool uses an oscillating tool holder for efficient grinding, then productivity is improved, but the device complexity increases
Solution Approach 1:
The patent integrates the oscillating mechanism directly into the tool holder assembly by mounting the tool holder on an eccentric rolling bearing that is part of the drive unit. This merging of the oscillating mechanism with the tool holder reduces overall device complexity while maintaining high grinding productivity through effective oscillating motion.
Solution Approach 2:
The eccentric rolling bearing automatically generates the oscillating motion required for efficient grinding as the drive shaft rotates. The system serves itself by converting simple rotational motion into the complex oscillating motion needed for productivity, without requiring additional oscillating elements or complex control mechanisms.
3Productivity
If the machine tool achieves high removal efficiency with large oscillation path, then productivity is improved, but the machine tool size increases
Solution Approach 1:
The eccentric drive mechanism generates a pendulum-like oscillating motion with a relatively large amplitude, enabling high material removal rates at the edges of the tool holder. This mechanical vibration approach achieves high productivity within a compact volume by creating an efficient oscillating path that maximizes material contact.
Solution Approach 2:
The eccentric positioning of the rolling bearing creates an asymmetric oscillation path that maximizes the grinding effectiveness at the tool holder edges. This asymmetric design achieves high removal efficiency in a compact configuration by concentrating the oscillation path where it is most needed for productivity.
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 solution enables high removal efficiency during grinding at the edge of the tool holder, achieving a large path with small eccentricity, and allows for a compact, lightweight, and efficient oscillating drive system in portable machine tools.
Implementation Method 1
a rolling bearing (28a, 28b) arranged eccentrically to a drive axis (18a, 18b) on a drive shaft (16a, 16b), which is designed to transmit movement from the drive shaft to the tool holder
Implementation Method 2
The drive unit includes, in particular, at least one electric motor. A drive shaft of the drive unit is, in particular, at least partially formed by an armature shaft of the electric motor
Data Source
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AI summary
The invention relates to a portable machine tool, in particular a grinding machine, with at least one oscillatingly driven tool holder (12a; 12b), with at least one drive unit (14a; 14b) which has at least one drive shaft (16a; 16b) with at least one drive axis (18a; 18b) intersecting the tool holder (12a; 12b) for driving at least the tool holder (12a; 12b), and with at least one bearing unit (20a; 20b) for a movable bearing of the tool holder (12a; 12b) about a bearing axis (22a; 22b) of the bearing unit (20a; 20b) that intersects the tool holder (12a; 12b). It is proposed that the drive axis (18a; 18b) be configured differently from the bearing axis (22a; 22b).