Machine Tool Layout With Rear Spindle for Vibration Control
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Solution Overview
Problem
Existing machine tools face issues with increased size and weight, leading to decreased machining accuracy due to altered natural frequency and increased vibration amplitude, as well as accuracy errors from lead screw placement affecting spindle movement.
Innovation Solution
A machine tool design featuring a rotation table unit and spindle unit with linear motors, where the spindle unit is positioned at the rear of the bed and linear motors are placed on either side to move the spindle unit along its axis, with the center of gravity aligned within the motor's thickness, reducing overall size and weight, and utilizing oil hydrostatic bearings for precise movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the tool holder downwardly holds a tool, then the tool can be positioned, but the height of the entire machine tool increases and the machine tool enlarges
Solution Approach 1:
The patent repositions the tool holder from a vertical downward configuration to a horizontal configuration on the rotation table. This dimensional change allows the tool to be positioned accurately without increasing the vertical height of the machine tool, thus resolving the contradiction between tool positioning capability and overall machine size.
2Ease of operation
If the machine tool is increased in size and weight, then the tool holder can accommodate the tool, but the natural frequency of the machine decreases while the amplitude of natural vibration increases
Solution Approach 1:
By moving the tool holder to a horizontal arrangement on the rotation table, the patent achieves proper tool accommodation without vertically stacking components. This maintains a compact machine footprint and weight, preserving high natural frequency and low vibration amplitude, thus maintaining machining accuracy.
3Ease of operation
If the lead screw is located below the spindle, then the column can be moved, but the movement driving force acts on the column as a moment that inclines the spindle
Solution Approach 1:
The patent extracts the lead screw from its conventional position below the spindle and relocates it to the rotation table unit. This separation removes the source of the inclining moment that caused spindle alignment errors, while the column movement function is maintained through the new configuration.
4Ease of operation
If the lead screw is located below the center of gravity of the column, then the column can be driven, but accuracy errors in the pitch or the like of the lead screw may potentially lower a movement accuracy of the column and incline the column
Solution Approach 1:
The lead screw is extracted from the column assembly and integrated into the rotation table unit instead. This relocation eliminates the accuracy errors and inclination problems caused by the lead screw being positioned below the column's center of gravity, while column driving functionality is preserved through the redesigned mechanism.
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 configuration enhances machining accuracy by reducing vibration amplitude, improving natural frequency, and ensuring smooth, accurate spindle movement, while allowing for easier installation and handling due to reduced size and weight.
Implementation Method 1
linear motors respectively arranged on opposite sides of the spindle unit. The linear motors are configured to move the spindle unit along the axis
Implementation Method 2
utilizing oil hydrostatic bearings for precise movement
Data Source
AI summary
A machine tool includes a rotation table unit including a rotation table configured to rotate with respect to a first axis. The rotation table unit is configured to move along a second axis that is orthogonal to the first axis. The machine tool includes a spindle unit including a spindle configured to rotate with respect to a third axis that is orthogonal to the first axis and the second axis. The spindle unit is configured to move along the third axis. The machine tool includes a bed that supports the rotation table unit and the spindle unit. A front part of an upper surface of the bed includes a recess in which the rotation table unit is arranged. The spindle unit is located at a rear part of the upper surface of the bed.