Patent GB-653011-A (GB)
Title: Improvements in grinding machines
IPC: B24B27/00
Filed: 1948-04-02
Abstract: 653,011. Internal and face grinding machine. ARMS, M. H., GROBEY, P. A., and BRYANT CHUCKING GRINDER CO. April 2, 1948. No. 9371. [Class 60] In a grinding machine a carriage is supported for sliding motion on a pair of substantially parallel guide bars one of said guide bars being rigidly fixed to a bed, and the other of said guide bars being carried so as to yield from and towards the fixed guide bar. General construction. A grinding machine comprises a bed 1 on which are mounted a work carriage 2, provided with a chuck 5 for a work piece 6, and a wheel carriage 3, provided with a spindle 7 carrying a grinding wheel 8. Mounting of carriages. Wheel carriage 3 is supported on a pair of cylindrical guide bars 12, 13, the guide bar 12 being rigidly carried by the bed 1, and the guide bar 13 being supported by spaced reeds 18 from a carrier bar 15 which is vertically adjustable at its opposite ends by screws 16 and is secured in adjusted position by screws 17 engaging the bed 1. The carriage 3 is supported on the guide bars 12, 13 by three sets of preloaded ball bearings, one of which engages the movable guide bar 13 and the other two engage the fixed bar 12. One support 12a for the fixed bar 12 is located between the two sets of bearings; a second support 12b for the fixed bar 12 is located outside the bearings, when the carriage is in its operative position the bearings are close to the supports 12a, 12b thus giving rigid support. Access of foreign material to the bearings is prevented by flexible bellows 25. The work carriage 2 is similarly supported on a pair of cylindrical guide bars 10, 11, the guide bar 10 being rigidly carried by the bed 1 and the guide bar 11 being movable. The mounting of the carriages 2, 3 in the manner described is stated to facilitate adjustment and maintenance of the planes of motion of the two carriages in the desired precise relationship despite warping changes due to seasoning of the bed and due to temperature changes and variations of temperature of differ- 'ent portions of the bed. Manual movement of wheel carriage. A lug 30 depending from the wheel carriage 3 is connected by a link 31 to an arm 33 secured at its lower end to a rock shaft 34 journalled in the machine base ; the upper end of the arm 33 is provided with a handle 36. Movement of work carriage. To facilitate access to the work piece when the grinding wheel is retracted and without requiring a long travel of the wheel carriage 3, provision is made for moving the work carriage 2 laterally of the travel of the wheel carriage 3. The work carriage 2 carries a vane motor 40, 'having a vane 41 fixed to a shaft 42 having a crank 45 connected by a rod 46 to an axially-movable non-rotatable feed screw 48 on which is threaded a rotary feed sleeve 49 journalled in the machine frame and arranged to be turned by rotation of a feed shaft 490 connected thereto through gears 491, 492. When the work carriage 2 is in the grinding position, a stop abutment 493 thereon engages the forward end of the feed screw 48, being held there by a counterweight connected to the work carriage 2 through a cable. When the motor 40 is actuated, the work carriage 2 is moved. The motor 40 is operated by compressed air or hydraulically, under the control of a valve 53 which is urged in one direction by a spring 55 and is moved in the other direction by an adjustable stop screw 51 carried by the wheel carriage 3 so that when the carriage 3 reaches a predetermined retracted position the work carriage 2 is automatically moved laterally of the machine to its inoperative position. Wheel carriage power traverse mechanism. An arm 60 is fulcrumed at 61 in the machine base and carries at its upper end a cross pin 66 engaged by a hook 65 on a latch 62 fulcrumed at 63 to the wheel carriage 3. The arm 60 is connected by a rod 70 to a crank pin 71 adjustable for throw on a crank arm 72. The rod 70 is adjustable in length, comprising telescoping sections clamped in adjusted relation by a serrated bar; a scale is provided to facilitate adjustment. The arm 72 is formed on a shaft 90 coupled by a Hookes joint 94-98 to a shaft 99 journalled in a bearing 100 supported on a table 102 clamped to the machine frame by a bolt 103. A motor 106, suspended from a platform 105 pivoted to the table 102. drives the shaft 99 through a belt 107 and worm and worm wheel 111. When the shafts 99, 90 are in axial alignment, the shaft 90 is driven by the shaft 99 with uniform angular velocity, and the wheel slide has simple harmonic motion with relatively rapid motion in the centre of the stroke and relatively slow motions towards the ends of the stroke. By adjusting the table 102 about the bolt 103 the shaft 99 is brought out of alignment with the shaft 90 and the latter is driven at a variable angular velocity, whereby the simple harmonic motion of the wheel carriage is modified to give substantially linear velocity throughout the major portion of the stroke, this minimising bellmouthing. Facing. For facing the work the work carriage is moved to an intermediate position in which the outer end face of the grinding wheel is opposite a portion of the end face of the work. The vane motor 40 for moving the work carriage, has a valve 151 loaded by a spring 162 to a position in which two sections of a line 44 leading from the control valve 53 to the vane motor are connected, while a line 163 is cut off from a discharge line 164. The valve is operated in the other direction by a roller 161 on an arm 160 on the shaft 42 of the vane motor. During internal grinding a valve 171 is set so that a branch line 168 from the line 44 communicates with a line 176 leading to the vane motor, so that supply to the motor is not cut off when the valve 151 is moved by the roller 161. When face grinding, the valve 171 is turned to connect pipe 163 to pipe 176 ; when the work carriage has reached an intermediate position, the roller 161 operates the valve 151 to shut off the supply line 44 and to open the appropriate side of the vane motor to exhaust through the line 176, valve 171, line 163, valve-151 and exhaust line 164. Rotation of the valve 171 to face grinding position throws down a stop bar 18D between abutments 182. 183. The abutment 182 is fixed to the machine frame 185 ; the abutment 183 is yieldingly carried by the work carriage 2 and is adjustable by a differential screw operated by a collar 198. The work carriage 2 is thus accurately located in its intermediate position for facing the work. Locking of wheel carriage during face grinding and trueing. A bar 210 is mounted for axial movement in the machine frame, rotation being prevented by a key 220 ; one end of the bar 210 is threaded into a sleeve 211 journalled in the machine frame; axial movement of the sleeve 211 is prevented, and the sleeve can be turned by a handle 214, a scale 215 being provided. A spring 223 urges the bar 210 axially to take up backlash. Collars 227, 228 are keyed on the bar 210 and are secured in axially adjusted position thereon by collars 232 threaded on the bar. A latch hook 240 on the wheel carriage 3 has a hook recess 241 engagable selectively with abutments 229, 230 on the collars 227, 228 respectively. When the hook 240 engages the abutment 229, the end face of the grinding wheel is adjusted to be in axial position to start face grinding of the work against which it may be fed by turning the hand lever 214; when the hook 240 engages the abutment 230, the end face of the grinding wheel is removed from face grinding position and retracted to a point where it is in position to be trued by a trueing device 245 mounted on the work carriage. The trueing device comprises a diamond holder 250 axially adjustable in a sleeve 251 pivoted on a support 253 so that it can be rocked downwardly, when the work carriage 2 is in grinding position, placing a diamond trueing tool 254 in position to true the wheel periphery ; during the downward rocking, a second trueing device 255 carried by the holder 250 sweeps across the end face of the grinding wheel to true it. When the latch 240 is in engagement with either of the abutments 229, 230 the wheelcarriage 3 is disconnected from the power traverse mechanism; the latch 62 which is adapted to engage the upper end of the power traverse lever 60. has an upwardly extending arm 260 and the latch 240 has a similar arm 261 ; the arms 260, 261 are in line with axially movable bars 266, 267 which engage a cam 270 operated by a handle 272. In extreme positions of the handle 272 one hook is raised and the other lowered ; in an intermediate position of the handle 272, both the hooks are raised so that the wheel carriage can be moved by manipulation of the handle 36 The table 262 on which the hooks 62, 240 are pivoted, is adjustable relative to the wheel carriage in the direction of movement of the latter by a screw 280 operated through intermeshing spiral gears 281, 282 by an adjusting shaft 283 having a handwheel 289. This adjustment compensates for grinding wear and trueing of the wheel face.