INTERNAL DIAMETER MEASURING METHOD FOR TRANSPARENT TUBE

• US 20170167854A1
• Filed: 11/30/2016
• Published: 06/15/2017
• Est. Priority Date: 12/15/2015
• Status: Active Grant

• Current Assignee: Mitutoyo Corporation
• Original Assignee: Mitutoyo Corporation
• Inventors: IMAIZUMI, Ryoichi
• Granted Patent: US 10,060,727 B2
• Time in Patent Office: Days
• CPC Class Codes: G01B 11/12 internal diameters
• CPC Class Codes: G01B 11/2433 for measuring outlines by shadow casting

Abstract

A transparent tube is placed in a parallel laser light beam emitted from a light projector and reaching a photoreciever, and a detection signal indicating an amount of light received corresponding to a width direction position of the parallel laser light beam is obtained from the photoreceiver. Peaks formed in the detection signal by beams reflected by an inner circumferential surface of the transparent tube and incident to the photoreceiver are detected; width direction positions of two intersection points where the peaks cross a predetermined threshold value are detected; the width direction positions of the light beam reflected by the inner circumferential surface of the transparent tube are calculated from an average value of the two intersection points; and an internal diameter of the transparent tube is measured from the width direction positions.

Claims

1. An internal diameter measurement method for an internal diameter of a transparent tube using a parallel laser light beam, the method comprising:

providing a light projector that forms the parallel laser light beam;

providing a photoreceiver that receives the parallel laser light beam from the light projector;

arranging the transparent tube between the light projector and the photoreceiver;

obtaining, from the photoreceiver, a detection signal indicating an amount of received light corresponding to a width direction position of the parallel laser light beam;

detecting a peak in the detection signal formed by a light beam reflected by an inner circumferential surface of the transparent tube and incident to the photoreceiver, detecting width direction positions of two intersections where the peak crosses a predetermined threshold value;

calculating, from an average value of the two intersection points, the width direction positions of the light beam reflected by the inner circumferential surface of the transparent tube; and

performing a geometric calculation from the width direction positions of the light beam such that the internal diameter of the transparent tube is measured.

2. The method according to claim 1, wherein said calculating further comprises calculating the width direction on two sides of the transparent tube such that the internal diameter of the transparent tube is measured from the width direction positions of the inner circumferential surface on the two sides.