Form measuring apparatus and measuring method for V groove center

Patent metadata

Field	Value
Publication number	US-9341459-B2
Application number	US-201414464184-A
Country	US
Kind code	B2
Filing date	Aug 20, 2014
Priority date	Aug 26, 2013
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

Controller executes a first scanning control, causing a driver to move a probe such that a tip scans along an inclined surface of a V groove to approach a center of the V groove, and a second scanning control, causing the driver to move the probe such that the tip scans along the inclined surface of the V groove to approach the center of the V groove from a side opposite that of the first scanning control. Angle calculator calculates an angle created between a direction of a deflection vector of the probe and a predetermined direction. Threshold value-correspondent coordinate obtainer obtains coordinates of the tip where the angle has changed to exceed a first threshold value during execution of the first scanning control and obtains coordinates of the tip where the angle has changed to exceed a second threshold value during execution of the second scanning control.

First claim

What is claimed is:

1. A form measuring apparatus comprising:
a probe having a tip configured to measure a measured object;
a driver configured to move the probe;
a probe coordinate detector configured to detect coordinates of the probe;
a deflection vector detector configured to detect a deflection vector of the probe;
an angle calculator configured to calculate an angle created between a direction of the deflection vector and a predetermined direction;
a tip coordinate calculator configured to calculate the coordinates of the tip based on the coordinates and the deflection vector of the probe;
a controller configured to execute a first scanning control, causing the driver to move the probe such that the tip scans along an inclined surface of a V groove to approach a center of the V groove, the controller further configured to execute a second scanning control, causing the driver to move the probe such that the tip scans along the inclined surface of the V groove to approach the center of the V groove from a side opposite that of the first scanning control;
a threshold value-correspondent coordinate obtainer configured to obtain, as first coordinates, coordinates of the tip where the angle has changed to exceed a first threshold value during execution of the first scanning control and obtaining, as second coordinates, coordinates of the tip where the angle has changed to exceed a second threshold value during execution of the second scanning control; and
a V groove center calculator configured to calculate coordinates of the V groove center based on the first coordinates and the second coordinates.

2. The form measuring apparatus according to claim 1 , wherein:
the controller is further configured to execute a third scanning control before executing the first scanning control, the third scanning control causing the driver to move the probe such that the tip scans along the inclined surface of the V groove to move away from the V groove center,
in the third scanning control, the controller causes the driver to move the probe until a moving distance of the tip from a position where the angle reached the first threshold value reaches a predetermined length,
the controller is further configured to execute a fourth scanning control before executing the second scanning control, the fourth scanning control causing the driver to move the probe such that the tip scans along the inclined surface of the V groove to move away from the V groove center, and
in the fourth scanning control, the controller causes the driver to move the probe until the moving distance of the tip from a position where the angle reached the second threshold value reaches a predetermined length.

3. The form measuring apparatus according to claim 2 , wherein, in the first and second scanning controls, the controller executes a fixed-height scanning control, where a fixed plane perpendicular to a length direction of the V groove is defined as a confining surface.

4. The form measuring apparatus according to claim 2 , wherein:
the controller is configured to execute a fifth scanning control causing the driver to move the probe such that the tip scans along the inclined surface of the V groove to approach the V groove center,
in the fifth scanning control, the controller generates a first target speed vector of the probe for fixed-height scanning control where a first plane parallel to the predetermined direction is defined as a confining surface, generates a second target speed vector of the probe for fixed-height scanning control where a second plane parallel to the predetermined direction and perpendicular to the first plane is defined as a confining surface, causes the driver to move the probe based on a combined vector of the first target speed vector and the second target speed vector, and detects, as a detected speed component, a component of the tip speed that is perpendicular to the predetermined direction and where the angle has reached one of the first threshold value and the second threshold value,
the first plane and the second plane move together with the tip, and
in the first and second scanning controls, the controller controls a component of the probe speed that is perpendicular to the predetermined direction based on the detected speed component.

5. The form measuring apparatus according to claim 1 , wherein, in the first and second scanning controls, the controller executes a fixed-height scanning control, where a fixed plane perpendicular to a length direction of the V groove is defined as a confining surface.

6. The form measuring apparatus according to claim 1 , wherein:
the controller is configured to execute a further scanning control causing the driver to move the probe such that the tip scans along the inclined surface of the V groove to approach the V groove center,
in the further scanning control, the controller generates a first target speed vector of the probe for fixed-height scanning control where a first plane parallel to the predetermined direction is defined as a confining surface, generates a second target speed vector of the probe for fixed-height scanning control where a second plane parallel to the predetermined direction and perpendicular to the first plane is defined as a confining surface, causes the driver to move the probe based on a combined vector of the first target speed vector and the second target speed vector, and detects, as a detected speed component, a component of the tip speed that is perpendicular to the predetermined direction and where the angle has reached one of the first threshold value and the second threshold value,
the first plane and the second plane move together with the tip, and
in the first and second scanning controls, the controller controls a component of the probe speed that is perpendicular to the predetermined direction based on the detected speed component.

7. A measurement method of finding a V groove center comprising:
obtaining, as first coordinates, coordinates of a tip of a probe where an angle created between a deflection direction of the probe and a predetermined direction changes to exceed a first threshold value during a first scanning where the probe is moved such that the tip scans along an inclined surface of a V groove to approach a center of the V groove;
obtaining, as second coordinates, coordinates of the tip where the angle changes to exceed a second threshold value during a second scanning where the probe is moved such that the tip scans along the inclined surface of the V groove to approach the V groove center from a side opposite that of the first scanning; and
calculating coordinates of the V groove center based on the first coordinates and the second coordinates.

Assignees

• Mitutoyo Corp

Inventors

• Noda Takashi
• Kamitani Hiroshi
• Mizukami Kazumi

Classifications

• G01B5/008 Primary

  using coordinate measuring machines · CPC title

• G01B5/204

  of screw-threads · CPC title

• G01B21/047

  Accessories, e.g. for positioning, for tool-setting, for measuring probes · CPC title