Patent GB-484759-A (GB)
Title: Improvements in and relating to vertical hydraulic broaching machine
IPC: B23D37/04
Filed: 1937-05-20
Abstract: 484,759. Hydraulic broaching-machines. TRIGGS, W. W. (Lapointe Machine Tool Co.) May 20, 1937, No. 14034. [Class 83 (iii)] A machine in which the broach B is pulled downwards through the work by apuller head 64 has a lifter head 25 for raising the broach, each head being actuated by a separate hydraulic mechanism controlled by separate manuallyoperated means. The work is mounted on a platen 21 and the upper part of the frame guides the lifter head which is operated by a vertical hydraulic cylinder 28. The lifter head, Fig. 3, comprises a lined recess 34 having a lower tapered end 37 to receive and guide the upper end of the broach. A latch 40 having a projection 42 engaging a shoulder 44 of the broach is normally held in operative position by a pivoted lever arm 58 whose slotted end fits over a pin 46 on the latch. As the broach approaches its lower limit of travel a fixed cam surface 60 engages the lever 58 and rocks it against a spring 53 thus withdrawing the latch and disengaging the broach which thereupon completes its stroke through the work under the action of the puller head 64. The latter is mounted on a main slide 66 connected to the piston rod 69 of the main hydraulic cylinder 71. The puller head comprises a pair of broach-gripping dogs 81 carried by pivoted studs 82 which carry interengaging lever arms 87, 90 normally urged by a spring 92 to move the dogs to gripping position. One of the studs 82 carries an arm 94 connected to a link 96 coacting with a cam 100 on a lever 102. As the puller head reaches its lower limit of travel the lever 102 engages a fixed stop to move the cam 100 to dotted line position and push back the link 96 to disengage the dogs from the broach. The dogs remain disengaged during the upward travel until, near the upper limit, a spring 104 actuates the lever 102 to shift the cam 100 and restore the dogs to gripping position. The hydraulic circuit is shown in Fig. 11. The main pump P is of variable delivery reversible type, the rate of delivery and direction being controlled from a handle 110 through levers 112 and 114, rack 115, and control 116. Automatic actuation of this control is effected through a sliding rod 120 having collars 124, 125, engaged by a block 122 connected to the main slide 66, this engagement serving to restore the pump to neutral position. The control mechanism is also connected to a valve V communicating with an adjustable back pressure valve 142. The pump ports 152, 151a are connected to the valve V through lines 151, 150, respectively and valve port 137 is connected to the reservoir through one-way check valve 154. The lifting cylinder 28 is supplied from a separate constant-delivery pump P<1> through' a valve V<1> the spindle of which is operated through lever mechanism from a pedal 167. This control mechanism is also connected through rod 169 to a slidable rod 172 carrying collars engaged by a projection 175 of the lifter head 25. This engagement restores the valve V<1> to a neutral position. At the beginning of a cycle the main slide and puller head are raised and the lifter head carrying the broach is started downwards by depressing the pedal 167. The pump P<1> then delivers through the heavy arrow lines in Fig. 11 to the upper end of cylinder 28. Exhaust from this cylinder passes through a needle valve 214 which determines the rate of downward movement. The handle 110 is at this time in neutral position and there is no delivery from the pump P. Surplus oil from the pump P<1> passes through relief valve R<1> and filter 206 and circulates round the casing of the main pump to lubricate and cool the same. As soon as the broach reaches position C, Fig. 2, wherein its upper end engages the puller head, the operator moves handle 110 downwards. The pump P now discharges through lines 151 and 74 to the upper end of cylinder 71 and moves the puller head downwards on the working stroke. Discharge from the cylinder 71 passes through the back-pressure valve 142 and then part of this oil flows to the intake side of the pump while the rest flows through relief valve R to the reservoir. The lifter head follows the broach downwards until, near the lower end of the stroke, the broach is unlocked and the collar 177 is engaged to shift valve V<1> to neutral. In this position the auxiliary pump delivery passes to line 205, filter 206, and casing of pump P to the reservoir. The lifter head now remains stationary while the puller completes its stroke through the work and reaches position E, Fig. 2, whereupon the rod 120 is actuated to return the valve to neutral and the broach is unlocked. After removing the work the handle 110 is moved upwards and the valve connections then direct the flow to the lower end of cylinder 71 moving the main slide upward. The discharge from the upper end of cylinder 71 is added to the pump discharge so that the return stroke is effected at increased speed. When the lifter head is engaged by the broach it is pushed upwards and after the lifter head leaves the cam 60 the broach is latched therein and the control 167 is actuated to direct fluid to the lower end of cylinder 28. The lifter then moves at higher speed than the main cylinder, draws the broach out of the puller head and returns it to the upper position A, Fig. 2, whereupon the valve V<1> is again automatically neutralized. When the puller head reaches its uppermost position the valve V is neutralized and the parts are in position for a fresh cycle. Specification 450,607 is referred to.