Counterforce Mechanism for Machine Axis Positioning
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Solution Overview
Problem
Existing machine axis systems face challenges in maintaining position accuracy and efficiency when counteracting forces such as gravity, particularly at higher velocities and accelerations, due to issues like metal fatigue, resonance, and energy consumption in direct motor drives, and inaccuracies in pneumatic or hydraulic counterbalancing systems.
Innovation Solution
A resilient coupling arrangement is used to apply a variable counterforce between the driven body and the support, allowing for accurate positioning without rigid coupling, reducing vibration transfer, and enabling the support to be held in place even when the drive power is removed, using components like coil springs or gas springs, and incorporating a damping mechanism and safety features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a direct motor drive is used to counteract forces on a machine axis, then positioning accuracy and dynamic response are improved, but energy consumption increases and the system cannot hold position without constant power
Solution Approach 1:
The patent applies a counterweight mechanism where a second carriage is positioned to balance the gravitational force on the first carriage. The counterweight carriage moves in opposition to the main carriage, creating a balanced system that reduces the energy required to maintain position while preserving positioning accuracy through coordinated control of both carriages.
2Force
If a counterbalance carriage with cables and pulleys is used, then gravitational forces are counteracted, but dynamic performance deteriorates at higher velocities and accelerations
Solution Approach 1:
The patent extracts the counterbalancing function from a traditional mechanical linkage system (cables and pulleys) and implements it through a simplified carriage-based mechanism. By removing the intermediate transmission elements, the system achieves direct force application that maintains dynamic performance at higher velocities while still counteracting gravitational forces effectively.
3Use of energy by moving object
If constant tension springs are used to cancel gravitational forces, then energy consumption is reduced, but metal fatigue and resonant vibrations occur
Solution Approach 1:
The patent replaces the durable but problematic constant tension spring with a carriage-based counterweight system that uses rigid mechanical components instead of elastic materials. This substitution eliminates metal fatigue concerns and resonant vibrations while maintaining the energy-saving benefits of gravitational counterbalancing.
4Force
If pneumatic or hydraulic cylinders are used for counterbalancing, then gravitational forces are counteracted, but control accuracy is reduced due to friction and hysteresis
Solution Approach 1:
The patent substitutes pneumatic or hydraulic cylinder systems with a purely mechanical carriage-based counterweight mechanism. This replacement eliminates the seals, valves, and fluid dynamics that cause friction and hysteresis, thereby maintaining force counteraction capability while significantly improving positioning accuracy and control precision.
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 provides reliable and robust counterbalancing without significantly affecting the support's position, maintaining accuracy and reducing energy consumption by allowing the support to be held in place without constant motor power, and offering a compact configuration with reduced brake power requirements.
Implementation Method 1
a resilient coupling arrangement (26) between the driven body (12) and the support (4)
Implementation Method 2
incorporating a damping mechanism
Data Source
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AI summary
A counterforce mechanism is arranged to exert a force on an object such that the magnitude of the force is made substantially equal and opposite to any other forces which may be acting on the object in the guided direction thereby allowing the object to maintain its desired position with minimum effort. The mechanism comprises a driven body (12, 62, 94), a drive (20, 60, 92) for moving the driven body, and a resilient coupling arrangement (26, 70, 88) for coupling the driven body to a portion of an object. A control arrangement is arranged to output a drive signal to the driven body drive to move the driven body to a location where it exerts a force on the object in the guided direction via the coupling arrangement, as determined by the control arrangement to minimise the effort necessary for the object to maintain its desired position. A machine axis and a machine tool incorporating such a counterforce mechanism are also described, together with methods of operation thereof.