Patent ID: 8480154

Claim:
A clamp structure for a tonneau cover of a pick-up truck, mounted to one of at least two frame sections of the tonneau cover to releasably secure the frame sections on a side wall of a cargo bed of the pick-up truck, the clamp structure comprising: a foundation rail connected to one of the frame sections, and having two side grooves formed on two side surfaces of the foundation rail, and a recess formed between the two side grooves; a sliding block having two side hangers extended into the two side grooves and slidably moving along the two side grooves, and a pivotal portion received in the recess; a clamp bolt having a pivotal end pivotally connected to the pivotal portion of the sliding block, and a thread end; a composite grip element movably mounted on the clamp bolt, and having a metal grip body which is formed with an engaging portion and an installation hole and a plastic sleeve which passes through the installation hole of the metal grip body and is formed with a first abutment flange and a second abutment end facing the sliding block, wherein the metal grip body has a hollow portion transversely communicated with the installation hole, and the plastic sleeve passes through the installation hole and the hollow portion; and a turning handle rotatably and movably connected to the thread end of the clamp bolt, and having a push surface to smoothly abut against the first abutment flange of the plastic sleeve of the composite grip element, so as to control the engaging portion of the metal grip body of the composite grip element to stably engage with the side wall of the pick-up truck.