Patent GB-625251-A (GB)
Title: Improvements in drilling machines
IPC: B23B41/02
Filed: 1945-03-21
Abstract: 625,251. Drilling long holes. CROSS, E. J. (Nordberg Manufacturing Co.). March 21, 1945, No. 7141. [Class 83 (iii)] A control-member is movably mounted on the base of a machine on which the tool-head is also slidably mounted, means being provided whereby the movement of the tool-head is governed by the control-member, and movement of the control-member is responsive to movement of the tool-head. As applied to a deep-hole horizontal drilling-machine, the cycle of spindle movements is a rapid feed up to the work followed by a slow drilling feed, a short rapid withdrawal and return to the work, followed by further drilling, a longer rapid withdrawal and return to the work, followed by continued drilling. The spindle 39 and associated motor 36, Fig. 1, are slidably mounted as a unit on a base 1, a rack on the spindle carrier engaging a pinion housed in a slidable cross-head in the well of base 1. The pinion also engages a stationary rack secured to a side-wall of the well, so that the spindle carrier moves with twice the velocity of the pinion-housing which is connected to the piston of a hydraulic-cylinder 14 located in the well of base 1. The cylinder is in circuit with a pump 10 and its associated motor 11. Extending lengthwise of the base is a fixed shaft and rack 48 on which is slidably mounted the control-member 51, and a second shaft 49 rotatably mounted on the base beneath shaft 48 and which passes through boss extensions on the back of the control-member. Two handles 146 and 152 are adjustably fixed to shaft 49. A rotatable shaft 119, and cams 138 and 141 are carried by brackets 116, 117, 118, Fig. 6, secured to the spindle-carrier. Electrical control boxes 225, 226, connect with the spindle motor, and with limiting switches in the control-member for the pump-motor and hydraulic-valve operating solenoids, the system being manually or automatically controlled at will. The change from rapid forward to drilling feed speed is accomplished through switch 104, Fig. 7, co-acting with cam-member 107, Fig. 8. In its forward movement, the bracket 118 contacts rod 108 causing the bevelled member 107 to operate against the plunger 105 of the switch 104; solenoids 206. 212 are thereby operated to control a valve-box in the hydraulic circuit. The control-member and spindle-carrier continue to move in unison for a pre-determined depth of drilling according to the setting of stops on spindle 85, Figs. 7 and 8. The block 78 is moved relatively forward by pinion 68 engaging the rack on shaft 48 through frictional contact with pinion 76, whereupon spring clip 94 depresses the plunger of switch 96a. The solenoids are energized, operating the valve control box to reverse the flow of fluid to the hydraulic cylinder, thus rapidly withdrawing the drill from the work, the controlmember remaining in its furthest position by virtue of spring-loaded plunger 100. Assuming the long withdrawal to be operating, the cam 141 contacts a projecting pin 143 on the handle assembly 146 causing the shaft 49 to be partially rotated whereby pin 58 in rocker arm 57, Fig. 7, breaks the frictional contact between the pinions 68 and 76 through the displacement of spring-loaded spindle 59 and hand wheel 71 assembly. Thus freed, the spring 83, Fig. 8, returns the block 78 to its original position as indicated by stop 84, closing the switches 95 and 96a and bringing the spindle carrier to the rapid forward feed again. The short withdrawal stroke is arranged during the forward feed of the spindle carrier through a roller 134 on bracket 117 contacting an interference plate 114 on the control-member, Figs. 1 and 7. A vertical rack 132 is depressed to operate ratchet-controlled gearing arranged to turn cam-shaft 119 sufficiently to bring a projection on cam 138 into the path of the pin 58 so that on the next withdrawal stroke the switches 95a and 96a are operated through cam 138 displacing pin 58 and spindle 59. Successive forward strokes rotate the cam-shaft 49 so that the stop 143 and the cam 138 operate the switches alternately. A slidable sleeve 300 on shaft 48 in conjunction with a pointer 301 in the control-member indicates the depth of each drilling. The withdrawal may be effected at will by manual operation of either handles 146 and 152. Valves are arranged in the hydraulic system to give a variable spindle feed.