TECHNICAL FIELD

The present invention relates to clamping devices configured to clamp workpieces.

BACKGROUND ART

Japanese Laid-Open Patent Publication No. 2010-179429 discloses a clamping device clamping a workpiece using a clamp arm by rotating the clamp arm based on displacement of a piston and a piston rod. The clamping device includes link mechanisms (first link and second link) disposed between the piston rod and the clamp arm, and the piston rod is provided with, on a side surface adjacent to an end thereof, an inclined part (wedge surface) coming into contact with a curved portion of the clamp. That is, the clamping device uses the link mechanisms to convert the displacement of the piston rod into the rotational motion of the clamp arm, and uses the wedge surface to guide the rotation of the clamp arm and control (lock) the rotation of the clamp arm when the workpiece is in a clamped state.

SUMMARY OF INVENTION

As described in Japanese Laid-Open Patent Publication No. 2010-179429, the clamping device that performs locking by bringing part of the clamp arm (or a rotation portion operating together with the clamp arm) into contact with the inclined part receives clamp reaction force from the clamp arm on the inclined part while the clamp arm is in a clamping state. In this case, a component of the clamp reaction force is applied to the piston rod in a direction along which the piston rod is pushed in. This may cause release of the lock of the clamping state in the clamping device in a case where the clamp reaction force is large.

Moreover, in a case where the thickness of the workpiece varies due to dimensional errors and the like, the piston rod may not reach a predetermined advanced position (position where the clamp arm is locked) even when the clamp arm clamps the workpiece, and the clamping device may not be able to lock the clamp arm. That is, the known clamping device has a narrow lock range to lock the clamping state of the clamp arm, and cannot accommodate variations in the thickness of the workpiece.

The present invention has been devised taking into consideration the aforementioned problems, and has the object of providing a clamping device capable of establishing an excellent locking state and, at the same time, capable of satisfactorily accommodating variations in the thickness of a workpiece by increasing a lock range.

To achieve the above-described object, a clamping device according to an aspect of the present invention comprises a body, a clamp arm rotated relative to the body and configured to hold a workpiece between the clamp arm and a support structure to create a clamping state, a drive mechanism including a displacement body displaced linearly, and configured to rotate the clamp arm based on displacement of the displacement body, and a push mechanism disposed at a position facing the clamp arm or a rotation portion rotated in an integrated manner with the clamp arm, the push mechanism being configured to come into contact with the displacement body to elastically push the displacement body toward the clamp arm or the rotation portion while the displacement body is displaced, wherein the displacement body includes a guide surface coming into contact with the clamp arm or the rotation portion to guide rotation of the clamp arm, and also to control the rotation of the clamp arm while the clamp arm is in the clamping state.

Since the clamping device described above includes the push mechanism elastically pushing the displacement body, the displacement body can be displaced without being interfered, and the guide surface of the displacement body can be brought into firm contact with the clamp arm or the rotation portion while the clamp arm is in the clamping state. Thus, the reliability of the lock (rotation control) of the clamp arm increases, resulting in a sufficient clamping state even when, for example, the size of the clamping device is small. In addition, even when the clamp arm is in the clamping state, the elastic push of the push mechanism provides a lock range allowing variations in the thickness of the workpiece by displacing the displacement body a certain distance. Thus, the clamping device allows dimensional errors in the workpiece and the clamping device and demonstrates stable clamping force.

The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.

