Load measuring device and load measuring method

Patent metadata

Field	Value
Publication number	US-2021055193-A1
Application number	US-201917040365-A
Country	US
Kind code	A1
Filing date	Mar 14, 2019
Priority date	Mar 30, 2018
Publication date	Feb 25, 2021
Grant date	—

Abstract

Provided is a load measuring device and a load measuring method, capable of preventing a measuring error caused by an initial load in a state where an elastic member is held by a pair of holding parts when a load of the elastic member at the time of stretching is measured. A pair of holding parts 5, 7 are caused to approach or space away with respect to each other relatively to an initial position at which the pair of the holding parts hold a close contact spring S, thereby making an initial load measured at the initial position zero, the pair of holding parts 5, 7 are caused to space away with respect to each other from a starting position being a position at which the initial load becomes zero, and a load at a time of stretching is caused to be measured.

First claim

1 . A load measuring device to measure a load of an elastic member, comprising:
a pair of holding parts that hold the elastic member; a driving part that drives the pair of the holding parts so as to approach and space away with respect to each other; a load measuring part that measures a load acting on the pair of the holding parts while holding the elastic member; a controlling part that controls the driving part and obtains the load from the load measuring part, wherein the controlling part causes the pair of the holding parts to approach or space away with respect to each other relatively to an initial position at which the pair of the holding parts hold the elastic member, thereby making an initial load measured at the initial position zero, and causes the pair of the holding parts to space away with respect to each other from a starting position being a position at which the initial load becomes zero, and causes a load at a time of stretching to be measured.

2 . The load measuring device according to claim 1 , wherein
the controlling part repeatedly causes the pair of the holding parts to approach and space away with respect to each other, thereby causing the pair of the holding parts to approach or space away with respect to each other to the starting position.

3 . The load measuring device according to claim 2 , wherein
the load at the time of the stretching is measured relatively to a displacement in micrometric units, and each approaching or spacing-away at the time of the repeatedly approaching and spacing-away is a fine motion in micrometric units.

4 . The load measuring device according to claim 1 wherein,
the elastic member is a close contact spring, and
the controlling part sets a displacement amount that is based on the approaching or the spacing-away of the pair of the holding parts with respect to each other relatively to the initial position to zero at the starting position, obtains a relation between the measured load and a displacement amount that is based on the spacing-away of the pair of the holding parts with respect to each other from the starting position, finds a linear function f(x)=ax+b of a linear region in which increase of the load to increase of the displacement amount in the relation is deemed as constant, and determines an intercept b of the found linear function f(x) as an initial tension of the close contact spring.

5 . A load measuring method to measure a load of an elastic member, comprising:
holding the elastic member with a pair of holding parts; measuring a load acting on the pair of the holding parts from a state where the elastic member is held; causing the pair of the holding parts to approach or space away with respect to each other relatively to an initial position at which the pair of the holding parts hold the elastic member, thereby making an initial load measured at the initial position zero; and causing the pair of the holding parts to space away with respect to each other from a starting position being a position at which the initial load becomes zero and measuring a load at a time of stretching.

6 . The load measuring method according to claim 5 , wherein
repeatedly causing the pair of the holding parts to approach and space away with respect to each other, thereby causing the pair of the holding parts to approach or space away with respect to each other to the starting position.

7 . The load measuring method according to claim 6 , wherein
the load at the time of the stretching is measured relatively to a displacement in micrometric units, and each approaching or spacing-away at the time of the repeatedly approaching and spacing-away is a fine motion in micrometric units.

8 . The load measuring method according to claim 5 , wherein
the elastic member is a close contact spring, and the load measuring method further comprises:
setting a displacement amount that is based on the approaching or the spacing-away of the pair of the holding parts with respect to each other relatively to the initial position to zero at the starting position;
obtaining a relation between the measured load and a displacement amount that is based on the spacing-away of the pair of the holding parts with respect to each other from the starting position;
finding a linear function f(x)=ax+b of a linear region in which increase of the load to increase of the displacement amount in the relation is deemed as constant; and
determining an intercept b of the found linear function f(x) as an initial tension of the close contact spring.

Assignees

• Nhk Spring Co Ltd

Inventors

• Nagasawa Kaoru
• Nukui Kotaro
• SHIGENO Suguru

Classifications

• G01N3/08 Primary

  by applying steady tensile or compressive forces (G01N3/28 takes precedence) · CPC title

• G01N2203/0292

  Coil spring · CPC title

• G01B21/042

  Calibration or calibration artifacts (G01B3/30, G01B9/02072 take precedence) · CPC title

• G01L5/00

  Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes · CPC title

• G01N3/12 Primary

  Pressure testing · CPC title