Patent GB-580130-A (GB)
Title: Improvements in honing or lapping machines
IPC: B24B33/02
Filed: 1944-05-11
Abstract: 580,130. Honing &c. machines. BURGESS, A. F. (Barnes Drill Co.). May 11, 1944, No. 9000. [Class 60] A honing or lapping machine for cylinders &c. has the tool expanded by a power-operated device actuated under the control of means limiting the expansion to a predetermined rate, means being provided for varying the rate of expansion operative automatically in response to a decrease in the actual rate of expansion, thereby allowing unrestrained operation of the power-operated device until normal conditions of operation are restored. The machine comprises a column carrying a work-support and guide rods for a head which is reciprocated thereon to carry the tool 16 into and through the work W, by a fluid pressure cylinder 21 in which is movable a piston 22 connected with the head by a rod 23. The tool is rotated by an electric motor M and a train of gearing 26-34, and is expanded by a push-rod 37 normally pressed upwardly by a spring 38 and moved downwardly to expand the tool by fluid pressure mechanism. This mechanism comprises a piston 40, Fig. 5, movable in a cylinder 41 in a block 42, the piston having an axial bore 44 receiving, in antifriction bearings 45, the rod 37. Fluid is supplied to the cylinder at a pressure above that required for normal operation, and control mechanism is provided to maintain normal operation except when abnormal conditions occur, for example, the tool may become loaded, or a hard spot or a constricted area may be encountered. The control mechanism is associated with an extension 46 of the piston 40 projecting through an aperture in the block 42 and a cap member 48, and provided with'a slot 49, in which is the control means comprising an abutment member 52 supported for transverse movement on rollers 53, 54 carried by the member 48. Mounted on the member 52 is a wedge member 58 having an inclined surface for engagement by a wear strip 51 extending across the slot 49; the member 58 is pivoted at 59 to the member 52 and its angle may be adjusted by a screw 60, so that the movement of the rod 37 depends upon the angle and rate of movement of the member 52. The member 52 is acted upon by two springs 62 and is moved by a pawl 71 carried by one arm of a bell-crank lever 72, and pressed by a spring 74 into engagement with ratchet teeth 75 on the member 52 ; the other arm of the lever 73 carries a follower 76 engaging a cam 77 driven from the tool spindle by gearing 80-83. Rotation of the cam through one-half revolution rocks the lever 73 so that the member 52 is moved, by the pawl, one step to the left, thereby allowing the rod 37 to be lowered to expand the hone, and during the remainder of the one revolution of the cam the pawl is carried back to its initial position. During normal operation of the machine, the member 52 is held in its advanced position during return of the pawl by the wedging action of the strip 51; when, however, the tool does not expand at its normal rate, the strip 51 does not contact the member 52 and the springs 62 move the member rearwardly with the pawl, thereby allowing full pressure of the fluid in cylinder 41 to act on the rod 37 until normal conditions are restored, the member 52 oscillating idly during such abnormal period. In order, at the end of a honing cycle, to disengage the pawl 71 from the teeth 75 and thus permit full retraction of the member 52, a lever 86 is provided, one end of which is adapted to engage a tail-piece 88 on the pawl, the other end carrying a screw 89 held by a spring 90 in contact with the extension 46, so that when this is raised by the spring 38 upon the cutting off of fluid from the cylinder, the pawl is rocked out of engagement with the teeth 75 ; a similar action may be effected by the attendant by energization of a solenoid SOL-1 which acts on the lever through a link 91 and lever 92. The movements of the member 52 also may be used to control the length of the working cycle, a limit switch LS-1 being provided for that purpose and adapted to be closed by movement of the arm 95 when engaged by the screw 60. In a modification, the member 52 is advanced continuously by gearing engaging rack teeth formed on its lower surface ; the member 52 is lifted from engagement with the gearing when abnormal conditions of operation occur, and the tool expansion lags. The control of the machine is effected by electric means as shown in Fig. 7, movements of the head 15 being transmitted by an endless chain 110 to a control mechanism 111 ; a pilot valve V1 and reversing valve V2 control the operation of piston 21, and a valve V3 controlling fluid supply to the tool expanding mechanism is under the control of a solenoid SOL-2.