Machine Tool Turntable Cooling and Bearing Rigidity
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Solution Overview
Problem
Rotary tables in machine tools face challenges in achieving high accuracy and rigidity while operating at high rotation speeds, as they are prone to thermal deformations and heat-related stress, which affect machining precision.
Innovation Solution
The implementation of an internal rotor-cooling apparatus with a cooling medium and cooling surfaces within the motor drive and bearing units, combined with external cooling of the stator unit, to effectively manage heat and prevent thermal deformations, along with the use of two separate bearing units spaced apart to enhance rigidity and prevent tilting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high rotation speeds are used to improve productivity, then productivity increases, but thermal deformations and heat-related stress increase causing machining precision to deteriorate
Solution Approach 1:
The cooling system is segmented into multiple independent cooling circuits, each targeting specific heat-generating components (motor drive, bearing units). This allows differentiated cooling strategies for different thermal zones, effectively managing heat distribution and preventing thermal deformations that would compromise machining precision at high rotation speeds
Solution Approach 2:
A cooling medium acts as an intermediary substance to transfer heat away from critical components. The cooling medium circulates through cooling channels in the rotor unit and bearing units, absorbing heat and preventing thermal deformations, thereby enabling high rotation speeds without sacrificing machining precision
2Temperature
If external cooling of stator casing is used to manage heat, then heat dissipation improves, but cooling effectiveness of internal components (motor core, bearing mounting) is insufficient
Solution Approach 1:
The cooling channels are nested within the rotor unit and bearing units, with cooling passages embedded in the motor core and bearing mounting structures. This nested arrangement allows the cooling medium to directly contact and cool internal components from the inside out, significantly improving cooling effectiveness compared to external cooling alone
Solution Approach 2:
The cooling system transitions from two-dimensional external surface cooling to three-dimensional internal cooling by embedding cooling channels within the motor core and bearing units. This dimensional change enables direct heat removal from internal heat-generating components, dramatically improving overall cooling effectiveness
3Device complexity
If a single bearing unit is used to simplify structure, then device complexity decreases, but rigidity and resistance to tilting moments are insufficient
Solution Approach 1:
The bearing system is segmented into two separate bearing units positioned at different locations along the rotational axis. This segmentation allows each bearing unit to independently support specific loads, with the first bearing unit handling radial loads and the second bearing unit providing additional support against tilting moments, thereby enhancing overall rigidity
Solution Approach 2:
The bearing support system transitions from a single-point support to a distributed multi-point support arrangement. By positioning bearing units at different axial locations, the system creates a three-dimensional support structure that effectively resists both radial forces and tilting moments, significantly improving rigidity
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 machining accuracy and rigidity, allowing for higher rotation speeds while minimizing thermal stresses and deformations, making the rotary table suitable for both turning and milling operations.
Implementation Method 1
the rotor unit, at least in the region of the motor drive and/or of the first bearing unit, has at least one rotor-cooling apparatus, comprising a cooling medium and at least one cooling surface, for the cooling and/or absorption of waste heat from the motor drive and/or from the first bearing unit
Implementation Method 2
comprising a cooling medium and at least one cooling surface, for the cooling and/or absorption of waste heat
Implementation Method 3
rotor-cooling apparatus, comprising a cooling medium and at least one cooling surface
Data Source
AI summary
A rotary table for a machine tool comprising a stator unit, a rotor unit rotatable at least about a rotational axis, wherein the rotor unit comprises at least one receiving unit for the reception of a workpiece, a first bearing unit for the mounting of the rotor unit in the stator unit, and an electromagnetic motor drive for the motorized driving of the rotor unit. The rotor unit, at least in the region of the motor drive and/or of the first bearing unit, has at least one rotor-cooling apparatus, comprising a cooling medium and at least one cooling surface, for the cooling and/or absorption of waste heat from the motor drive and/or from the first bearing unit.