Coaxial Rotary Table for Electric Discharge Machines

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Solution Overview

Problem

Conventional rotary tables in electric discharge machines are bulky and heavy due to the requirement of two axes and separate bearings, making them difficult to construct as compact and lightweight units.

Innovation Solution

The rotary table design incorporates a housing with a power unit, speed reducer, fixing member, shaft, bearing, face plate, and rotation detector, where the power unit and speed reducer are aligned on the same axis, and the rotation detector is mounted on a projecting portion of the shaft to cover the speed reducer, reducing the overall dimension and weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two axes (C-axis and D-axis) with separate bearings are used to enable synchronous rotation of power unit and face plate, then rotational synchronization is achieved, but the rotary table becomes bulky and heavy

Engineering Contradiction:
Improverotational synchronizationVSAvoidrotary table weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The invention merges the C-axis and D-axis rotations by aligning them on the same rotational axis. The power unit and face plate are positioned coaxially, allowing both to rotate synchronously around a single axis, thereby eliminating the need for separate bearing sets and reducing overall weight.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The face plate is nested within the housing structure, and the power unit is positioned inside the housing as well. This nested arrangement allows components to share space efficiently, reducing the external dimensions of the rotary table while maintaining functional requirements.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If two axes with separate bearings are used for synchronous rotation, then rotational synchronization is achieved, but the axial dimension increases

Engineering Contradiction:
Improverotational synchronizationVSAvoidaxial dimension
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

By combining both rotational functions into a single axis, the invention eliminates the need for sequential arrangement of two bearing sets along the axial direction. This merging reduces the axial dimension while maintaining synchronous rotation capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention repositions components from a sequential axial arrangement (where C-axis and D-axis would be stacked) to a radial/concentric arrangement. The power unit and face plate are distributed in the radial direction around the common axis, converting an axial dimension problem into a radial space utilization solution.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If conventional rotary table design with two axes is used, then synchronous rotation is achieved, but compactness and lightness cannot be realized

Engineering Contradiction:
Improvesynchronous rotationVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention simplifies the overall structure by merging two independent axis systems into one unified rotational system. This reduces the number of components, simplifies the drive mechanism, and makes the rotary table more compact while maintaining synchronous rotation functionality.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP2929971B1Electric discharge machine with rotary table
Publication Date: 2019.05.22 FANUC LTD
  • EP2929971B1 patent drawingFigure 1
  • EP2929971B1 patent drawingFigure 2
  • EP2929971B1 patent drawingFigure 3~4

AI summary

A rotary table device of an electric discharge machine is provided with a face plate (6) on which a workpiece is placed, a power unit (2) that generates a driving force for rotating the face plate, and a speed reducer (10) connected to the power unit (2) and configured to reduce the rotational speed of the power unit (10). The respective centers of rotation of the power unit (2) and the speed reducer (10) are disposed on one and the same axis, and a rotation detector (14) for detecting a rotational position of the face plate (6) is disposed in a space defined by an outer peripheral portion of the speed reducer (10) and an inner wall of a housing (18) of the rotary table device.