Touch Probe Measurement Plane Switching for Machine Tool Accuracy
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Solution Overview
Problem
The existing measuring methods for machine accuracy in machining centers are limited by a restricted range of measurable angles of rotation, particularly in lathes with tool posts that can rotate around the B axis, leading to interference issues and reduced measurement accuracy when the angle exceeds 40 degrees.
Innovation Solution
The solution involves switching the measurement plane and axis directions in correspondence to the angle of rotation, allowing the measurement plane to be positioned where the lever rod and reference sphere do not interfere, and using a measurement plane moving mechanism to prevent contact, enabling high-accuracy measurements over a wide angular range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the touch probe is installed to measure machine accuracy in a lathe with B-axis rotation, then the measurement can be performed using conventional five-axis measuring methods, but the measurable angle of rotation is restricted to about 40 degrees due to interference between the lever rod and reference sphere
Solution Approach 1:
The measurement plane is dynamically switched based on the rotation angle of the touch probe. When the rotation angle exceeds a predetermined threshold, the measurement plane is changed from the first measurement plane to the second measurement plane, allowing continuous measurement across the entire rotation range without interference between the lever rod and reference sphere.
Solution Approach 2:
The invention changes the parameter of measurement plane orientation according to the rotation angle. By switching between different measurement planes (first measurement plane for smaller angles, second measurement plane for larger angles), the system maintains measurement capability across the full rotation range while avoiding geometric interference.
2Ease of operation
If the measurement plane is fixed in the conventional five-axis measuring method, then the measurement procedure is simple, but the lever rod contacts the reference sphere before the tip sphere at angles beyond 40 degrees, making measurement impossible
Solution Approach 1:
The measurement plane is dynamically selected based on the rotation angle condition. The system automatically switches between the first measurement plane (for angles within threshold) and the second measurement plane (for angles exceeding threshold), ensuring measurement feasibility while maintaining procedural simplicity through automated plane selection.
Solution Approach 2:
The invention introduces a measurement plane switching mechanism that acts as an intermediary between the fixed measurement setup and the varying rotation angles. This switching mechanism ensures that the appropriate measurement plane is selected to avoid interference, maintaining measurement reliability across all angles.
3Adaptability or versatility
If estimation is used to determine the center of the reference sphere in immeasurable angular ranges, then measurement can continue beyond 40 degrees, but the measurement accuracy is widely lowered
Solution Approach 1:
Instead of using estimation in immeasurable ranges, the invention dynamically switches to a second measurement plane that is specifically configured to avoid interference at larger angles. This allows direct measurement with high accuracy across the entire rotation range, eliminating the need for estimation and maintaining measurement precision.
Data Source
AI summary
A method and a device can measure machine error of an axis of rotation in a tool post having a touch probe without restriction of an angular range of an angle of rotation. Directions of a measurement plane and a measurement axis in a five-axis measurement are switched in correspondence to a range of the angle of rotation in a touch probe. The five-axis measurement is carried out by setting a position in a direction of a measurement axis in a measurement plane to a position where a reference sphere does not interfere with a lever rod of the touch probe as occasion demands. The five-axis measurement is carried out, for example, by setting the measurement plane to a position which is perpendicular to a line connecting an estimated center of the reference sphere and a center of a tip sphere or the lever rod of the touch probe.