Patent GB-1327387-A (GB)
Title: Lapping honing or the like machine
IPC: B24B33/02
Filed: 1970-11-27
Abstract: 1327387 Grinding; workholders CAV Ltd 27 Nov 1970 [11 Dec 1969] 60437/69 Headings B3B and B3D  A machine for abrading material from the internal surface of a workpiece, such as a liquid fuel injection nozzle, comprises a supporting structure 10 on which is mounted a lap, hone or other tool supporting member 14 and a work supporting member 20 in such positions that the tool 25 and workpiece when carried by the members are coaxial, means 17 for effecting relative rotation between the tool and workpiece, means 22 for effecting relative axial reciprocation between the tool and workpiece, means 24a for sensing resistance to relative movement between the tool and workpiece and for producing a signal having a magnitude dependent upon the magnitude of the resistance, and means 19 for adjusting the effective diameter or relative radial position of the tool in accordance with the signal whereby if the resistance to relative movement increases the effective diameter or relative radial position of the tool will be reduced and vice versa. The supporting structure consists of a base 10 and pedestals 11, 12, 13. The pedestal 12 carries a member 14 rotatably supporting a hollow spindle 15 which is driven by a belt 26 from a motor 17 and has screw threaded cap 31 for clamping the tool 25a to the spindle, the tool being radially expandable by a tapered element 35 connected by a rod 36 and a clamp 37 to a piston 45 in a cylinder 46 carried by a member 19 on the pedestal 11, the clamp permitting relative rotation between the rod 36 and piston 45. The pedestal 13 carries a hydraulic motor 22 for reciprocating a carriage 21 on the bed 10, the carriage having a housing 50 for bearings 50a supporting a hollow sprindle 53 formed with a flange 53a connected by a torque anchor device 24 incorporating a strain gauge 24a to the carriage 21 to thereby resist rotation of the spindle. The spindle carries a member 20 having a fixed jaw 51a and a movable jaw 51b which can be rocked about a pivot 51c to grip a workpiece by axial movement of a conical head 23b on a shaft 23 connected to a piston 23a in a cylinder 23b. The jaws have resilient linings 52a, 52b or are mounted in a cardanic or gimbal suspension. The machine is provided with a programme control means which, upon operation of a start switch and with a workpiece held in the jaws 51a, 51b of member 20, actuates the motor 22 to advance the workpiece over the tool 25 which has abrasion paste supplied to its abrading surface. The motor is controlled by a solenoid operated valve actuated by micro switches to effect reciprocation of the workpiece. The tool is rotated by the motor 17 and the piston 45 is moved to cause the tapered element 35 to expand the tool 25 at a fast rate and engage the workpiece. The strain gauge senses the resistance to rotation of the workpiece and at a predetermined value causes the piston to expand the tool at a slow rate or step-by-step until a second predetermined valve of restistance is reached and expansion of the tool is discontinued, lapping continuing for a predetermined time or, if a second predetermined value is not reached during a single reciprocation of the workpiece, a single movement of expansion of the tool may be effected and expansion of the tool continued until the second predetermined value is again exceeded. After a predetermined time, the lapping is discontinued with the workpiece withdrawn from the tool and the tool contracted. The motor 22 may be controlled so as to abrade one part of the bore of the workpiece, i.e. a "tight" spot. In either embodiments, the control circuit compares the reaction to torque with the time for one reciprocation of the workpiece, the torque is measured by the resistance to rotation of the spindle 15, the current in the motor 17, or the mounting of the motor 17 may incorporate a strain gauge. The expansion of the lap may be effected by a rotary air or electric motor, the operating rod 36 having a screw thread connection with the motor, or the lap may be formed with a hollow chamber subjected to fluid pressure.