POWER HACKSAW

摘要

1488229 Power hacksaw KEURO MASCHINENBAU GmbH & CO KG 3 June 1976 [6 June 1975] 22925/76 Heading B5L A power hacksaw having a base 1 provided with clamping jaws 2, 3, for holding a workplace, and having a housing 5 pivotally mounted at 6 on the base and in which is mounted a reciprocable saw bow 8 the back of which is provided with wings (10), 11, 12 engaging guides 7 with which the housing is provided for guiding the reciprocating movement of the saw bow, the saw bow being adapted for setting the saw blade at a small angle to its direction of stroke, and the hacksaw having a motor-driven crank mechanism for reciprocating the saw bow, which mechanism is arranged in the housing above the back of the saw bow and is situated, in the direction of the saw bow stroke, substantially within the range of movement of the saw bow (defined by the length of the saw bow plus the length of its stroke), and is rotatable about an axis lying in or parallel to the working plane of the saw bow and perpendicular to the direction of the stroke, the crank mechanism including an eccentric crank-pin 16 engaged from above in a groove 17 arranged on the back of the saw bow parallel to the wings, is characterized in that the housing is supported by an hydraulic cylinder-piston unit 23 mounted on the machine base for the automatic control of the cutting pressure and of the feed movement of the saw blade in the direction towards the workpiece, which unit supports the housing through a bellcrank lever 26 which is pivotally mounted at 27 in the region of its angle on the housing and acts through a substantially horizontally extending push-rod 31 articulated to one of its free ends upon an eccentric 33 carried by the rotation shaft of the crank mechanism for the lifting away and re-application of the saw blade at the reversals of reciprocating movement. The piston/cylinder unit is as shown in Fig. 3 and includes an adjustable needle valve 49 which controls the rate of downward movement of piston 37 in cylinder 34 and thus controls the increment of feed applied to the blade during the idle stroke, in which the blade is lifted from the workpiece. An adjustable valve member 52 located between the upper chamber 42 of the cylinder and an external fluid reservoir 53 provides a predetermined but adjustable resistance to upward movement of the piston 37 and thereby limits the pressure applied to the blade of the hacksaw during its cutting stroke.