| 摘要 |
In machines for opening of a tapping hole, for example in tapping hole boring machines, carriage holder (4) with boring bar and boring machine is swung up via four-bar linkage (5) by a lifting cylinder (10) out of an optionally obliquely sloped working or boring position into a neutral position out of the area of a runner. The boring angle is adjustable on connecting rod (7) of four-bar linkage (5). To securely keep the lifting device for automatic changing of the boring bar always in the horizontal neutral position, piston rod (11) of lifting cylinder (10) is linked to the free end of angle lever (13) which is pivoted around axis (16) located stationary on lifting frame (8). The angle lever is hinged via link plate (14) to upper short lever arm (15) of lifting arm (6). Link plate (14) with short lever arm (15) and angle lever (13) in the horizontal neutral position of the lifting device forms self-locking knee link (18). To adjust the working or boring angle, one of joints (22, 23) of connecting rod (7) is adjustable on an arc with a center of curvature which coincides with the axis of the other of joints (22, 23) of connecting rod (7) at the time, when the lifting device is in the neutral position. |
