Inside-diameter measuring unit, floating joint mechanism unit, and measuring unit

A floating joint mechanism part interposed between an object to be supported and a support frame part configured to support the object to be supported, the floating joint mechanism part configured to allow relative translation and rotation of the object to be supported with respect to the support frame part, the floating joint mechanism part comprising:

• a coupling block fixedly coupled to the object to be supported and configured to be translated and rotated integrally with the object to be supported;
• a rotation-allowing mechanism part configured to allow rotation of the coupling block with respect to the support frame part;
• and
• a translation-allowing mechanism part configured to allow translational displacement of the coupling block with respect to the support frame part
• the rotation-allowing mechanism part includes a sphere disposed between the coupling block and the support frame part, and
• the translation-allowing mechanism part includes:
• a guide shaft provided to either one of the coupling block and the support frame part and extending in a direction of guiding translation;
• and
• a guide hole provided in the other one of the coupling block and the support frame part to receive the guide shaft and allow the guide shaft to slide.

A measuring unit comprising:

• a measuring part configured to bring a contact point into contact with an object to be measured to measure a dimension of the object to be measured;
• a support frame part configured to support the measuring part;
• and
• a floating joint part interposed between the support frame part and the measuring part to allow relative translation and rotation of the measuring part with respect to the support frame part, wherein
• the floating joint part includes:
• a coupling block fixedly coupled to the measuring part and configured to be translated and rotated integrally with the measuring part;
• a rotation-allowing mechanism part configured to allow rotation of the coupling block with respect to the support frame part;
• and
• a translation-allowing mechanism part configured to allow translational displacement of the coupling block with respect to the support frame part
• the rotation-allowing mechanism part includes a sphere disposed between the coupling block and the support frame part, and
• the translation-allowing mechanism part includes:
• a guide shaft provided to either one of the coupling block and the support frame part and extending in a direction of guiding translation;
• and
• a guide hole provided in the other one of the coupling block and the support frame part to receive the guide shaft and allow the guide shaft to slide.