Hydrostatic Bearing Preloading Control for Vertical Lathe Rigidity
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Solution Overview
Problem
Existing part holders for large mass machining in vertical lathes face challenges in maintaining rigidity and optimal dynamic behavior as the weight of the part varies, particularly due to limitations in hydrostatic bearings which suffer from reduced rigidity and increased risk of damage from weight fluctuations and thermal expansion.
Innovation Solution
A part holder system featuring a worktable supported by hydrostatic bearings with a preloading bearing in dynamic parallel configuration, equipped with sensing and control units to automatically modulate preloading based on real-time weight changes, maintaining optimal rigidity and preventing damage by adjusting fluid pressure and gap height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrostatic bearings are used to support the worktable, then startup vacillations are eliminated and dynamic friction is reduced, but rigidity decreases when load varies from design load
Solution Approach 1:
The patent applies dynamics by making the preloading force adjustable and adaptive to actual load conditions. The control system continuously monitors the load on hydrostatic bearings and dynamically adjusts the preloading force through actuators, transforming a static bearing system into a dynamic one that maintains optimal rigidity across varying loads.
Solution Approach 2:
The patent changes the parameter of preloading force applied to hydrostatic bearings. By varying this parameter based on actual load conditions, the system maintains optimal operating conditions for the bearings, ensuring consistent rigidity and preventing slider contact regardless of whether the load is lighter or heavier than design load.
2Adaptability or versatility
If the load on hydrostatic bearings decreases below design load, then fluid pressure reduces and gap increases, but rigidity decreases and fluid flow increases
Solution Approach 1:
The patent applies anti-weight by introducing a preloading mechanism that counteracts the effect of reduced load. When the actual load is lighter than design load, the preloading mechanism applies an additional force to maintain the optimal preloading condition on hydrostatic bearings, effectively compensating for the load deficiency and maintaining rigidity.
3Force
If the load on hydrostatic bearings increases above design load, then fluid pressure increases and gap reduces, but risk of slider contact increases
Solution Approach 1:
The patent applies preliminary action by proactively adjusting the preloading force before slider contact can occur. The control system continuously monitors load conditions and preemptively modifies the preloading force through actuators, preventing the gap from becoming too small and avoiding slider contact even when loads exceed design specifications.
4Adaptability or versatility
If compensation devices are added to maintain minimum operating load, then load range is extended, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a control system that performs multiple functions: it monitors load conditions, calculates required preloading adjustments, controls actuators, and protects against slider contact. This multi-functional approach extends the load range while avoiding the need for separate compensation devices for each function, thereby limiting the increase in overall system complexity.
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 system ensures optimal rigidity and prevents damage by automatically adapting to weight variations, maintaining optimal operation regardless of the part's weight and thermal expansions, thus extending the range of suitable loads and enhancing machining stability.
Implementation Method 1
at least one hydrostatic supporting bearing (14), adapted to support said worktable (11) on said footing (13)
Implementation Method 2
means (16) for modulating a preloading imparted to said at least one supporting bearing (14)
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
A part holder (10) for parts to be machined with machine tools, particularly for parts having a large mass to be machined in vertical lathes, which comprises: a worktable (11) for supporting a part (12), a footing (13) for supporting the worktable (11), at least one hydrostatic supporting bearing (14) for supporting the worktable (11) on the footing (13), at least one preloading bearing (15), which is interposed between the worktable (11) and the footing (13), in a dynamic parallel configuration with respect to the supporting bearing (14), means (16) for modulating a preloading imparted to the supporting bearing (14), means (17) for sensing at least one functional parameter (A) of at least one chosen supporting slider (14a) of the supporting bearing (14), and a central unit (18) for controlling the modulation means (16). The control unit (18) is functionally connected to the sensing means (17) so as to receive from them estimates of the functional parameter (A), and to the modulation means (16) so as to drive them as a function of these estimates.