Hydrostatic Rotary Table Support for Stable Machining Tolerances

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Solution Overview

Problem

Large machine tools, such as vertical lathes, face challenges in maintaining tight machining tolerances due to variations in the weight of semi-finished products during machining, which affect the stability and precision of the machining process.

Innovation Solution

A table group with a hydrostatic skid system and dog mechanism that uses pressurized fluid to maintain a constant lifting action and stiffness, allowing for precise support and rotation of semi-finished products by adjusting the pressure chambers and pistons to counteract weight changes, ensuring consistent machining tolerances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional support system is used for the table, then the structure is simple, but the machining precision deteriorates due to weight variations affecting stability

Engineering Contradiction:
Improvemachining toleranceVSAvoidsupport system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent employs a hydrostatic support system where multiple skids with pressure chambers receive pressurized fluid to generate lifting forces. This hydraulic mechanism compensates for weight variations of semi-finished products, maintaining constant table elevation and stiffness throughout machining operations, thereby ensuring consistent machining tolerances despite the increased system complexity

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The system dynamically adjusts the pressure of fluid supplied to each skid's pressure chamber based on the detected weight distribution. By changing the pressure parameter in real-time, the system maintains optimal lifting forces and table stiffness regardless of product weight variations, resolving the contradiction between precision and complexity

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the table supports varying weights of semi-finished products, then the system is adaptable, but the machining precision deteriorates due to stability changes

Engineering Contradiction:
Improveweight accommodationVSAvoidmachining tolerance
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The system incorporates detection means that continuously monitor the weight distribution on the table and provide feedback signals. This feedback controls the pressure supplied to each skid's pressure chamber, automatically adjusting the lifting forces to compensate for weight variations and maintain constant table elevation and stiffness, thereby preserving machining precision across different workpiece weights

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The support system transitions from a static configuration to a dynamic one where the pressure in each skid's pressure chamber can be independently adjusted. This dynamic adaptation allows the system to respond to varying weight conditions in real-time, maintaining optimal performance and machining precision regardless of the semi-finished product weight

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If hydrostatic skids are used to reduce friction, then the ease of operation improves, but the device complexity increases

Engineering Contradiction:
Improvetable rotation smoothnessVSAvoidhydrostatic system complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent implements a hydrostatic bearing system where pressurized fluid is supplied to pressure chambers in each skid, creating a fluid film that separates the table from the support structure. This eliminates direct mechanical contact and friction, enabling smooth table rotation and easier operation, though it increases system complexity through the addition of fluid supply infrastructure

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 ensures consistent machining tolerances and reduced friction, allowing for precise machining operations even with varying product weights, meeting the stringent requirements of the sector.

Implementation Method 1

a plurality of hydrostatic skids (40) for supporting the table (14) by means of pressurized fluid, capable of providing a lifting action F1

Methodology Applied
Scientific EffectHydrostatic lifting: Hydraulic Press

Implementation Method 2

a plurality of dogs (60), adapted to operate by means of pressurized fluid on the table (14), providing a contrasting action F2

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP4157581B1Table group for a machine tool
Publication Date: 2024.06.05 INNSE BERARDI SPA
  • EP4157581B1 patent drawingFigure 1
  • EP4157581B1 patent drawingFigure 2
  • EP4157581B1 patent drawingFigure 3

AI summary

A table group (10) for a machine tool (1) comprises a support assembly (12), a rotational table (14), a ring gear (20) provided with an inner face (20') and an upper face (20''), integral with the table (14), a plurality of main hydrostatic skids (40), detection means adapted to detect the lifting action (F1) generated by the main skids (40), a plurality of dogs (60) and electronic management means operatively connected to the main skids (40), the dogs (60) and the detection means, configured to control the dogs (60) to generate a contrasting action (F2) such that the lifting action (F1) is equal to a predetermined constant nominal load (P*), which is greater than the weight of the semi-finished product and is either smaller than or equal to a maximum load (Pmax) which can be borne by the main skids (40).