| 摘要 |
<p>A method of horizontally and vertically guiding a cutter advance mechanism involves adjusting and fixing each individual cutter of a plurality of cutters for radial change of direction with respect tot he apparatus and by guiding the individual cutters are guided in the circumferential direction during its advance. The individual cutters are provided with a tip which is pivotally attached to its front portion. Wedge surfaces which may be deployed are provided in the vicinities of the front and rear ends of the cutters so as to engage the support frame. Two additional wedge surfaces are provided at side surfaces of the central cutter, others of the cutters are provided with a further wedge surface at respective sides thereof facing away from the central cutter.</p> |
