Patent GB-275167-A (GB)
Title: Improvements in or relating to rotary spindle machine tools
IPC: B23Q5/26
Filed: 1927-05-14
Abstract: 275,167. National Automatic Tool Co., (Assignees of Galloway, R. M.). July 30, 1926, [Convention date]. Drilling-machines.-A machine tool such as a drilling, reaming, or like machine comprises a bed 1 carrying a pair of tool heads having rotary spindles 9, 10 and 5, 6 arranged on opposite sides of the work holder 4, each head being traversed by means or a pair of hydraulic cylinders which are diametrically arranged on opposite sides of the centre line of the head to give a central thrust on the tool. Multiple spindle tool heads may also be fitted to the heads 5, 6. The spindles are driven from a power pulley 11 which drives through a hand-operated master clutch 13, a main shaft 12 connected by further gearing 15 and 21 to a ccuntershaft 22 having splined connection with the gear 21 and driving the spindle 9 through gears 28, 29. The spindle 10 is driven by a similar gear train from the shaft 12. Casings 30 are provided at each end of the machine to enclose the gears 15 and 21. In order to provide for individually driving either of the spindles 9, 10 a clutch 33 operated either automatically or by a hand lever 36 is provided in each of the spindle-driving gear trains. The translation of the tool heads to and from the work is effected by hydraulic power, each tool head being actuated by a pair of cylinders C, C' arranged symmetrically on either side of the spindle. In this way any tendency of the tool heads to twist on the guideways 7, 8 is avoided and the guideways may be located close together beneath and in line with the cylinders C, C<1>. The bed may have an unbroken upper surface connecting the guides 7, 8 thus preventing the entrance of chips, dirt &c. The pistons P, P<1> are operated from a low pressure pump 40 which is driven from the shaft 12 and which supplies fluid from a reservoir R in the bed support to pipes 41, 42. The flow of fluid to the cylinders is automatically controlled so that the tools are brought quickly to the work, then fed at a slower speed and finally quickly withdrawn. The delivery pipe 44 from the pump is connected to a distributing-valve 45, comprising a cylinder 47 connected to the cylinders C, C<1> by a system of pipes comprising a pipe 49 for the rapid approach movement of the tools, a small pipe 50 with a valve 51 for the slow feed movement and a pipe 48 for the quick withdrawal movement. Exhaust fluid from the cylinders passes through the distributing valve to a pipe 52 connected to the reservoir. Movement of the valve piston p is effected by means of a rod 54 which is normally urged by a spring 58 into the position (Fig. 12) which causes the rapid withdrawal movement of the tool-heads. The movement of the rod 54 is contro led by spring pressed interference members 61, 62 which in their raised positions engage with a shoulder 63 on the rod 54. The interference members are depressed by dogs 64, 65 adjustably fixed to the too! head. Thus in the position shown in Fig. 12a, the valve is in position to cause the rapid approach movement of the tool head. At a predetermined point the dog 64 depresses the member 61 against its spring 59 whereupon the valve moves to the position, to cause the slow feed movement. On completion of the work the dog 65 depresses the member 62 and the valve moves to the position shown in Fig. 12 to cause the rapid withdrawal movement. The valve rods 54 may be manually controlled independently by handles 66. Both valve rods may also be moved simultaneously from a hand crank 67 to bring the automatic translating means into operation. The supply pipe 50 which effects the slow feed movement is provided with a needle valve whose opening may be regulated up to a predetermined maximum by a milled head 77, Fig. 9. While the slow feed is in operation the remainder of the pump output is conveyed back to the reservoirs through a relief line 72. If, as in the case of a tool breakage, it is desired to withdraw the tools before completion of the feed, the interference members may be depressed by a hand lever to allow the valve to return to the withdrawal position. While the work is being removed and replaced the entire output from the pump may be by-passed by automatic means operated by the tool beads. Each bypass valve comprises a cylinder 83 and piston 84. The valves are connected in series with a branch pressure line 44<x> and pipes 85, 86 and reservoir R. Thus in the position shown in Fig. 12 the pump output is flowing round the by-pass. The valves are urged towards this position by springs 87 but may be held in a position to close the by-pass by interference members 93 engaging collars 92 on the valve spindles. During the movement of the piston valves to the positions in which they effect the rapid approach movement, an arm 94 on the rod 54 engages a collar 91 on the by-pass valve spindle 90 to shift the valve so as to close the by-pass and the valve is held in this position by the member 92 until, during the withdrawal movement, dogs 95 on the heads depress the members 93 and allow the valves to move so as to open the by-pass circuit. To enable the forward position of the head to be accurately determined a rod 96 connected with the tool head carries an adjustable stop member 97 which engages a fixed abutment member 98 resting against a machine face on a bracket 100 to stop the feed. The abutment member may comprise a number of stop pieces 98<a>, 98<b> mounted on a rod 103 which may be oscillated to bring any stop into position against the bracket 100 to give a number of different feed movements. The automatic means for throwing out the main clutches 33 comprises a three-armed lever 107 mounted on a bracket 105 and connected to the clutch arm by a rod 103. Upon forward movement of the head a dog 109 thereon depresses the lever arm 107<c> to engage the clutch. On the withdrawal movement the dog passes over the arm 107<c> and engages the arm 107b to cause the disengagement of the clutch. In order to adjust the tools axially with respect to their heads, the piston rods are connected to their heads by means of screwed portions engaging nuts 110 which may be rotated in the tool heads by worm gearing 111. Various modifications of the means controlling the head translating mechanism are described. In one modification, for continuously reciprocating the tool head, the piston p carries the rod 114 of a piston 116 working in a cylinder connected at opposite ends to an oscillatory valve 120 which is connected to a pressure pipe 119 and return pipe 122 (Fig. 14). In the normal position of the oscillatory valve, the piston p is moved by the fluid pressure to the rapid withdrawal position but at the end of this movement the oscillatory valve is moved by an abutment 123 on the tool head to shift the piston p to initiate a fresh forward cycle. The step-by-step movement of the piston p may be effected by the above described interference members to control the movements of the tool head. In a further modification, particularly suitable for drilling through spaced walls, the valve p is designed to produce the following series of movements.-(1) Rapid forward traverse up to the work (2) Slow drilling feed through the first wall (3) Rapid forward traverse to bring the tool to the next wall (4) A slow feed through the second wall (5) A rapid withdrawal movement. In a further modification a rotary disc valve under spring control is employed, the valve being released periodically by dogs on the tool head to allow the valve to rotate step by step between limits determined by a series of circumferentially arranged stops on an annular member secured to the valve disc. In another modification, Fig. 18, a rod 143 carried by the valve p is urged by a spring against abutments formed by a pair of discs 149, 150, and a collar 152 on a rod 145 having a helical groove engaged by a pin 147 secured to the tool head. During the rotation of the rod 145 produced by the movements of the tool head, the rod 143 passes successively from the disc 149 to the disc 150 and collar 152 thus causing the movement of the piston p to effect the required speed changes. In a further modification, Fig. 20, the valve rod 54 is moved by means of stepped surfaces 162 on a cam member secured to the tool head and acting through a bell crank lever 160. In another modification the valve rod may be controlled by a single interference member having a number of stepped shoulders which come successively into engagement with a collar on the valve rod as the interference member is moved downwards step by step by dogs on the tool head. The lubricant for the cutting tools is pumped from a reservoir located in the leg 3 of the table, the pump being driven from the shaft 12 by a belt and the fluid being delivered through nozzles 177 and falling into a drip pan 178 whence it returns to the reservoir through a pipe 179.