Load measuring device and load measuring method

A load measuring device to measure a load of an elastic member, comprising:

• a pair of holding parts that hold the elastic member, the elastic member being a close contact spring;
• 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, 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.

A load measuring method to measure a load of a coil spring, comprising:

• holding the coil spring with a pair of holding parts at ends of the coil spring from outer peripheries of the ends, respectively;
• measuring a load acting on the pair of the holding parts holding the coil spring at the ends from the outer peripheries of the ends, the load including an initial load caused by the coil spring bent according to inclination of the coil spring relative to an axis between the holding parts and acting on the holding parts at an initial position performing the holding of the ends of the coil spring;
• causing the pair of the holding parts to approach or space away with respect to each other relatively to the initial position at which the pair of the holding parts hold the coil member, thereby making the initial load being measured zero;
• and thereafter
• causing the pair of the holding parts to space away with respect to each other to stretch the coil spring from a starting position being a position at which the initial load being measured by the load measuring part becomes zero and measuring a load at a time of the stretching from the starting position.

A load measuring method to measure a load of an elastic member, comprising:

• holding the elastic member with a pair of holding parts, the elastic member being a close contact spring;
• 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;
• 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.