Gripping device

1. A gripping device comprising:

a gripping portion configured to be displaced between a closed position in which a workpiece is grasped and an open position in which the workpiece is released;

a holding portion configured to hold the gripping portion;

a shaft portion that extends from the holding portion;

a support portion configured to support the shaft portion such that the gripping portion faces the workpiece;

a driving unit configured to displace the gripping portion between the closed position and the open position; and

a moving mechanism configured to move the support portion in an axial direction of the shaft portion, wherein

the support portion is configured to support the shaft portion such that when a load acts on the shaft portion in the axial direction, the shaft portion is slidable relative to the support portion by the load.

2. The gripping device according to claim 1 , further comprising:

a displacement sensor configured to detect a displacement of the shaft portion in the axial direction; and

a control unit configured to control the driving unit based on a detection result of the displacement sensor, wherein

the control unit is configured to displace the gripping portion from the open position to the closed position when the shaft portion slides relative to the support portion.

3. The gripping device according to claim 2 , wherein

the shaft portion includes a shaft portion body that is slidable relative to the support portion, and a protruding portion that extends in a direction intersecting the axial direction from the shaft portion body,

the support portion supports the protruding portion from vertically below such that the axial direction is a vertical direction,

the displacement sensor is configured to detect a displacement of the protruding portion relative to the support portion, and

the control unit is configured to displace the gripping portion from the open position to the closed position when the protruding portion rises relatively to the support portion while the support portion is being lowered such that the gripping portion is moved close to the workpiece.

4. The gripping device according to claim 3 , further comprising:

a biasing member configured to bias the shaft portion so as to press the protruding portion against the support portion.

5. The gripping device according to claim 1 , wherein

the gripping portion includes an elastic wall that reciprocates under an action of an external force, a plurality of arms extending from the elastic wall, a tubular peripheral wall which extends in a direction different from that of the plurality of arms from a periphery of the elastic wall, engagement projection portions disposed on a front end of the peripheral wall, and an internal space surrounded by the elastic wall and the peripheral wall,

the holding portion includes a cap that covers an opening of the gripping portion, a flow path forming portion that extends from a central portion of the cap, and a flange portion extending from the cap and including engagement recess portions which engage with the engagement projection portions, and

the shaft portion includes a first end portion connected to the flow path forming portion and a second end portion supported by the support portion.