Patent ID: 8517713

Claim:
An apparatus for stretching a plastic film longitudinally thereof, the apparatus comprising: a plastic film feeder by which the plastic film is fed longitudinally thereof and intermittently, the plastic film having opposite surfaces and opposite side edges; a stretching member and a board disposed on opposite sides of the plastic film to be opposed to the surfaces of the plastic film and to each other when the plastic film is fed longitudinally thereof; and a drive by which the stretching member is advanced toward the board to be pressed against the plastic film and the board between the side edges of the plastic film to stretch the plastic film longitudinally thereof when the plastic film is stopped temporarily, the stretching member being then retracted from the board and kept apart from the plastic film by the drive, wherein the stretching member comprises a plurality of rollers each of which includes a circumferential edge having a circular axial section, the rollers being arranged widthwise of the plastic film and mounted on a beam, the circumferential edge being opposed to the board, the drive being connected to the beam, the apparatus further comprising: an additional drive by which the beam is moved widthwise of the plastic film; and a control device connected to the drive and the additional drive, the drive and the additional drive being controlled by the control device so that the beam can be advanced toward the board to make the circumferential edge pressed against the plastic film between the side edges of the plastic film, the beam being then moved by the additional drive so that the rollers can be rolled widthwise of the plastic film, the beam being then retracted from the board so that the circumferential edge can be kept apart from the plastic film.