Workpiece Holding Structure for Force-Balanced Rotary Machining
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Solution Overview
Problem
Current machine tools are inadequate for processing asymmetrical and fully rotation-symmetrical workpieces, as they struggle with force imbalance and thermal inaccuracies, limiting their ability to handle high forces and precise machining.
Innovation Solution
A machining center with a workpiece absorption unit featuring a sled assembly and rotary table, equipped with a vertically adjustable centering tip and a symmetrically designed superstructure that integrates a pinole, allowing for stable fixation and processing of workpieces with high forces and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a pivoting workpiece carrier with off-center force introduction is used, then the machine structure can be more compact, but machining accuracy deteriorates due to force imbalances and thermal effects
Solution Approach 1:
The patent applies asymmetry by positioning the column and drive mechanisms offset from the centerline of the workpiece carrier. Specifically, the column is arranged laterally displaced from the vertical workpiece carrier axis, and the drive for the counterholder center is positioned separately from the workpiece carrier axis. This asymmetric arrangement allows compact packaging of powerful drives and robust frame structures while maintaining accurate force introduction along the workpiece axis, thereby resolving the contradiction between compactness and precision.
2Power
If powerful drives and robust frame structures are implemented for high forces, then machining capability improves, but thermal forces cause frame bending and accuracy deterioration
Solution Approach 1:
The patent introduces a rigid column as an intermediary element between the drive mechanisms and the workpiece. The column serves as a stiff force transmission path that conducts driving forces directly to the workpiece while isolating the frame structure from direct thermal and force loads. This intermediary structure allows powerful drives to be implemented without transmitting thermal expansion and bending forces to the workpiece, thus maintaining both high power capability and machining accuracy.
3Force
If the workpiece carrier supports the weight of workpiece, workpiece spindles, and counter-bearing, then the structure can handle heavy loads, but the bearing and rotary motor must be designed larger increasing complexity
Solution Approach 1:
The patent segments the load-bearing functions by introducing a separate column structure that independently supports the workpiece and counterholding device. The column acts as a dedicated load-bearing element that transfers forces directly to the machine bed, separating the support function from the rotary table and bearing system. This segmentation allows the use of smaller, less complex bearings and rotary motors while maintaining high load-bearing capacity through the rigid column structure.
Data Source
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AI summary
The invention relates to a workpiece holding unit for a machine tool, in particular in a machining center, comprising a machine bed (1), a slide assembly (2) movable in the Z direction on the machine bed (1), a rotary table (3) mounted on the slide assembly (2) with a clamping unit (9) for a workpiece (W), a vertically extending column (4), and a machining tool (5.1) mounted on the column (4), which is movable on the column (4) in a vertical Y direction and in a horizontal X direction, wherein a first receiving surface (2a) and a second receiving surface (2b) are arranged on both sides of the slide assembly (2) movable in the Z direction towards the rotary table (3), and a superstructure is arranged on the first receiving surface (2a) and the second receiving surface (2b), which extends upwards and over the rotary table (3) and has means for fixing the workpiece (W).