US2165898A - Grinding machine - Google Patents

Description

July 1l, 1939.

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UNITED STATES PATENT OFFICE GBINDING MACHINE Maxwell I. Mathewson and August L. Krause, Providence, lt. I., assignors to Brown and Sharpe Manufacturing Company, a corporation of Rhode Island Application November 14, 1935, Serial No. 49,772

89 Claims. (Cl. 51..-95)

The present invention relates to improvements operate with a reversing lever to reverse the in grinding machines. table motor. In the illustrated machine, a novel It is a principal object of the invention to proarrangement of reversing switches and operatvide a grinding machine of novel and improved ing connections therefor from the reversing lever construction which is well adapted for the peris provided which is particularly well adapted to formance of accurate and dependable work over limit the overrun of the table uDOn reversal a wide range of operating conditions, and for within acertainable limits. The connections either manual or automatic control. provided comprise a right and a left limit or re- It is another object of the invention to provide VcrSing Switch, and right and left SlOW-dOWn l0 in a grinding machine of the general type herein switches which are controlled by means of a cam l0 described, e novel and improved control system actuated by the movement 0f the reversing lever which eiects a more effective coordination in the from one operating position to the other. With operation of the several operating units of the the arrangement described, each of the slowmachine, than has heretofore been achieved,` down and reversing switches iS rendered Operaand which is particularly constructed and artive when the reversing lever reaches a predel5 ranged to permit of a centralized and automatic termined angular position, so that the table is control of the several units of the machine in electrically slowed and then stopped in a posiaccordance with any one of a number of diierent tion which corresponds t0 lh@ angular DOSiliOn operating cycles as required for different classes reached by the reversing lever, and may be dcof work. termlned within narrow limits through the oper 20 It is a further object of the invention to modify ation of the electrical braking connections hereand improve certain of the operating mechanisms inafter described.

in a machine of the general type herein disclosed In Order 150 provide a DOSVC limit fOr In0V- to secure a more eiiicient and satisfactory operament of the table in each direction where it may tion of the several cooperating units, and parbe desired to move the grinding wheel beyond ticularly to adapt the several mechanisms i'orthe ncrrnal Sini) DOSitlOn again-St 0r C101 lv ad automatic control in connection with applicants .iB-cent a Shoulder 0n the WOrk, 'DWG DOStlVc SlODS control system hereinaiter set forth, are provided on the machine frame, which are The invention is herein disclosed in a prearranged l0 engage with and positively stop ferred form in a grinding machine of the general movement of the table and reversing lever in each 30 type which comprises a longitudinally movable direction when moved manually an appreciable work table having supported thereon a rotatable distance beycnd the normal StOD DOSlil0n With work holder in the form of the usual head stock the Present cOnStrllcllOn. the table SlnW-OWn and tail stock, a power driven grinding wheel switches are connected to slow down the table spindle, a wheel spindle carriage which ls suponly when the fest-Slow clutch le in lbs high a5 ported on cross ways for movement toward and Speed DOSitiOn.

away from the work, and cross feed connections Features of the machine herein described and fOr mOVlnE the carriage at either a feeding or illustrated, but not claimedl relating particularly rapid rate toward and away from the work. to the operating and control devices for impart- The head stock and work table of the present lne translators movements t0 the reciprocating 4o machine are driven from separate direct eurent work table form the subject-matter 0f n divisional motors which are controlled by field rheostats to aDlJliCatiOn Serial NO- 157,19()y llcd October 4, permit a wide latitude in the rate of drive. The 1937. head stock motor is carried on the head stock The cross feed mechanism Drnvldcd Wil-h the casing, and is connected through reduction gears Present construction fOr feeding the Wheel Spin- 46 and a silent chain drive to provide a novel and Clle Carriage OWard and away flOIn the Work. emclent self-contained driving unit. The table comprises e rotatable feed Screw and e hand motor is reversible to reverse the direction of wheel adjustably connected thereto for manuel drive, and is connected through a power hand operation of the feed. Automatic operation is clutch and a fast-slow clutch in series therewith, secured by means 0f a reciprocating pawl which 60 so that alternate fast and slow driving rates are is arranged for engagement with ratchet teeth available for either power or manual operation formed on the hand wheel. In accordance with of the table. one feature of the present invention, a dwell sur- Reciprocation of the table is controlled by face or bare spot is provided in the ratchet teeth means of reversing dogs on the table which coto limit the feed to depth. Inasmuch as the ad- Il vancing movement of the hand wheel under the influence oi the pawl is thus always stopped at exactly the same point, it will readily be seen that with the construction illustrated an extremely fine adjustment of the depth power feed to any desired fraction of a tooth of the ratchet, may be obtained by disconnecting and turning the hand wheel back the desired amount.

With the present construction, the pawl may be connected for continuous reciprocation through driving connections from the table motor, or may have imparted thereto an intermittent feed motion which is controlled vby the table reciprocation through connections actuated by the table reversing lever.

In connection with the cross feed mechanism above described, there is provided a novel control device in the form of two stop pins on the cross feed hand wheel, a control slide provided with actuating cam and stop surfaces arranged in the path of said pins, and a control switch which may be operatively connected to control certain other operating units of the machine. This control device may be rendered operative during the manual operation of the cross feed to positively limit the feeding and backing-off movements imparted to the wheel spindle carriage, and also to prevent the rapid advance of the grinding wheel into interfering engagement with the work, and is also arranged to operate in connection with the electrical control system hereinafter described, to provide for an automatic control of the starting and stopping oi' the several cooperating units of the machine from the cross feed hand wheel.

In accordance wtih another feature of the present invention, a novel and improved mechanism is provided for imparting to the grinding wheel spindle carriage, a rapid movement through a predetermined distance toward and away from the work. This mechanism comprises specifically a reciprocable lever and yielding spring connections for moving the feed screw axially in either direction through an exactly predetermined distance. The reciprocable lever is actuated from a crank shaft to which is imparted successive 180 increments of rotation alternatively to advance and to retract the carriage by means of an electric motor driving and braking unit.

Further in accordance with the present invention, an adjustable cam is provided on the crank shaft for stopping the motor and applying the brake, so that the crank shaft may be stopped in each of its alternative positions corresponding to the extreme throw of the actuating lever in each direction. With this construction and mode of operation of the quick traverse movement including the yielding spring connection between the lever and the axially movable feed screw, an

exact positioning of the carriage in either its forward or back position, is secured regardless of minor variations in the angular stop position of the crank shaft.

With the present construction, separate driving motors are provided for supplying lubricant to the various bearings of the machine, and for supplying coolant to the point of grinding contact with the work. The supply of coolant is controlled by means of a valve which is actuated by a solenoid alternatively to turn on or shut oi the supply of coolant. The grinding wheel spindle is continuously driven at a high rate o! speed during the operation of the machine, by

aisance means of a separate motor through a belt drive which may be of any ordinary description.

In carrying out the present invention, a novel and improved system of controls has been provided which is arranged in conjunction with the several mechanical and electrical features herein set forth to secure a more completely automatic operation of the machine, to permit the rapid setting up of the machine and subsequent control by the operator of the several operating units for the performance in an accurate and dependable manner of any desired cycle of operations.

The control devices include a main starting and stopping control switch for the machine which serves to control the operation of the main grinding wheel motor, the oil pump motor, the coolant pump motor, and a generator motor which drives a head stock generator and a table generator, which in turn supply power for the head stock and table motors and the direct current control circuit hereinafter to be described. Separate control knobs are provided tor controlling the operation of the head stock and table, and also the cross feed rapid movement of the wheel spindle carriage.

With the present machine there are also provided a number of manually operable switch controls which enable the operator readily to set up the machine for a number of different operating cycles. In order to enable the operator simultaneously to start the head stock and table reciprocation, an automatic control switch is provided which may be set to bring the table motor under the control of the headstock control knob.

In order to provide for a substantially automatic operation of the machine, as for instance, where similar grinding operations are to be performed successively upon identical work pieces. a manually operable switch control is provided which may be set to bring the head stock, coolant, table, and cross feed rapid movement under the control of the cross feed hand wheel, so that the manipulation of the hand wheel in advancing the grinding wheel toward the work, serves to start the operation of the several cooperating units, and the movement of the hand wheel in backing off the grinding wheel similarly serves to arrest the operation of these units to permit the placing of a new work piece in the machine.

In order to set up the machine for plunge grinding, there is provided a table run-stop switch which acts when moved to stop position to disable the connections for shifting the powermanual clutch to power position, so that there can be no possibility of injury to the machine or work through the accidental starting of the table.

In order to set up the machine for the operation of truing the grinding wheel, there is provided a true grinding control knob which operates when moved to truing position to shift the control of the several cooperating units of the machine, so that these units can operate only in the desired manner to perform the truing operation irrespective of any possible accidental or unskilled manipulation of the several machine controls while the truing operation is being performed.

For the convenience of the operator in manipulating the machine, there are also provided separate manual control switches for determining the position of the fast-slow table clutch respectively for power and for manual operation of the table. The control circuits of which these switches are a part. are so arranged that the conl. ABHADlNG.

aieascs trol of the slow-fast clutch is automatically shifted from one to the other of these switches as the power-manual clutch is shifted from power to manual position. and vice versa. In order to control the amount of the table dwell, there is provided a control switch which may be located in any one of three operating positions to provide a long, or medium, or extremely short dwell at the end of the table movement in each direction according to the character of the work and the rate at which the table is being driven.

The several features of the present invention consist also in the devices, combinations and arrangement oi' parts hereinafter described and claimed, which together with the advantages to be obtained thereby, will be readily understood by one skilled in the art from the following description taken in connection with the accompanying drawings, in which Fig. 1 is a view in front elevation of a grinding machine embodying the several features of the invention; Fig. 2 is a view in left side elevation of the machine; Fig. 3 is an enlarged' detail view of the solenoid controlled coolant valve shown in Fig. 2, the parts being shown in section to illustrate the construction thereof; Fig. 4 is a plan view from beneath, of substantially the parts shown in Fig. 3; Fig, 5 is a view of the head stock unit looking from the right, the supporting table structure being shown in section; and a portion ol the head stock drive being shown in section; Fig. 6 is a sectional view taken on the line 6 6 of Fig. 5; Fig. 7 is an enlarged view in front elevation illustrating particularly the table drive, overlying portions of the machine having been broken away to show underlying parts; Fig. 3 is a sectional view taken substantially on the line 3 3 of Fig. 7, being a somewhat modified plan view of the table driving connections; Fig. 9 is a sectional view taken on the line 9 3 of Fig. 7, to illustrate particularly the power-manual clutch and solenoid control therefor; Fig. 10 is a sectional view taken on the line lll-Ill of Fig. 7, illustrating particularly the table slow-fast clutch and solenoid control therefor; Fig. 11 is an enlarged detail view in front elevation with certain overlying parts broken away to iilustrate particularly the reversing lever and reversing switch mechanism therefor, the parts being illustrated in a hypothetical half-way position; Fig. 12 is a sectional view taken on the line l2-I2 of Fig. 1l; Fig, I3 is a detail sectional view taken on the line Il-H of Fig. 12, showing the mechanism for reciprocating the cross feed pawl actuating crank from the reversing lever; Fig. 14 is an enlarged detail view in front elevation, of the cross feed hand wheel unit including the power cross feed pawl and actuating crank, and control slide; Fig. 15 is a sectional view in lei't elevation taken on the line IS-IS of Fig. 14; Fig. 16 is a detail sectional view taken on the line iB IG of Fig. 15, to illustrate particularly the control slide; Fig. 17 is a sectional view in rear elevation taken on the line Il l'l of Fig. 15, showing particularly the relationship of the cross feed hand wheel and slide; Fig. 18 is a plan view of the parts shown in Fig. 14; Fig. 19 is a sectional plan view taken on the line Ii| i9 oi' Fig. 16; Fig, 20 is an enlarged detail view in rear elevation and with certain portions of the machine broken away to illustrate particularly the mechanism for imparting cross feed rapid movement to the wheel spindle carriage; Fig. 21 is a detail sectional view taken on the line 2| 2I of Fig. 20, to illustrate particularly the crank shaft for imparting rapid movement to the wheel Examiner spindle carriage, and the starting and stopping switch control mechanism therefor, the parts being shown in the positions taken when the carrlage is moved to its fully advanced position; Fig. 22 is a view similar to Fig. 21, with the parts shown in the positions taken with the carriage in its fully retracted position; ma. 23 is a sectional view taken on the line 23 23 of Fig. 20, and illustrating particularly the cross feed screw and connections for imparting cross feeding and rapid movement to the wheel spindle carriage; Fig. 24 is a detail sectional view forming a downward continuation of Fig. 23, to illustrate particularly the motor and braking mechanism for the wheel spindle carriage rapid movement; Fig. 25 is a sectional view taken on the line 25-25 of Fig. 24, illustrating particularly the solenoid for controlling the brake; Fig. 26 is a sectional view in front elevation taken on the line 26 28 of Fig. 23, to illustrate particularly the grinding wheel spindle and driving connections therefor; Fig. 27 is a sectional view illustrating in detail a portion of the mechanism shown in Fig. 26, to illustrate particularly the mechanism i'or reciprocating the grinding wheel spindle; Fig. 28 is a sectional view taken on the line 23-28 of Fig. 27; Fig. 29 is a plan view of the parts shown in Fig. 27; Fig. 30 is a sectional view taken on the line 30-30 of Fig. 27: Fig. 3l is a sectional view taken on the line II-Il of Fig. 27, to illustrate particularly the solenoid control for starting and stopping spindle reciprocation; Fig. 32 is a developed view on an enlarged scale, of a portion of the spindle reciprocation clutch control cam shown in dotted lines in Fig. 28; Fig. 33 is an enlarged view in front elevation illustrating particularly the left half of the control panel for the machine, a portion thereof being broken away to illustrate particularly the switches controlled by the head stock and table knobs; Fig. 34 is a sectional view taken on the line "-34 of Fig. 33, to illustrate certain of the control elements on the panel including the main starting and stopping switch, the head stock motor rheostat, the hand wheel fast-slow switch, and the automatic cross feed hand wheel control switch; Fig. 35 is a sectional view taken on the line 35-35 of Fig, 33, illustrating particularly the connections for controlling the head stock starting, stopping and jog switches from the head stock knob; Fig. 36 is a sectional view taken on the line 33 36 of Fig. 35, illustrating on an enlarged scale the head stock jog switch; Fig. 37 is a detail sectional view looking frombelow, taken on the line 31-31 of Fig. 33, to illustrate on an enlarged scale the head stock stopping switch; Fig. 38 is a sectional view looking from below, taken on the line 33 38 of Fig. 33, to illustrate particularly the table starting switch; Fig. 39 is a sectional view taken on the line 39 of Fig. 33, to illustrate particularly the head stock starting switch; Fig. 40 is an enlarged view in front elevation of the right hand half of the control panel for the machine, a portion of the panel being broken away to show particularly the table reversing switches, and the control switches actuated by the spindle carriage rapid movement control knob; Fig. 41 is a sectional view taken on the line 4|-II of Fig. 40, to illustrate certain of the control mechanisms for the machine including the connections for operating the rapid movement forward and back switches from the rapid movement control knob, the table motor rheostat, the plunge cut control switch, and the table dwell switch; Fig. 42 is a sectional view taken on the line 42-42 of Fig. 40, to illustrate u particularly the connections for actuating the truing control switch from the truing control knob; Figs. 43 to 46 inclusive, are similar views of the table reversing switch connections illustrated in Fig. 40, and with Fig. 40 illustrate in tive successive steps the positions taken by said switch connections during the movement of the reversing lever to reverse the direction of table drive from right to left; Figs. 47 and 48 constitute a wiring diagram of the electrical connections for the machine, Fig. 47 illustrating particularly the electrical connections on the machine control panel, and Fig. 48 illustrating the subsidiary switch connections controlled thereby for controlling the operation of the several operating units oi.' the machine; and Figs. 49 and 50 constitute an explanatory diagram of the electrical connections, Fig. 49 being an explanatory diagram of the electrical connections for certain of the operating units, and Fig. 50 being an explanatory diagram more particularly of the direct current control circuit of the machine.

The machine illustrated in the drawings as embodying in a preferred form the several features of the present invention, comprises a base |02, a work supporting table |04 which is arranged to slide in ways |06 on the base, a head stock bracket |06 adjustably secured on the table, a foot stock also carried on the table, and a grinding wheel carriage ||2 which is supported on cross ways ||4 on the base.

The head stock unit comprises a rotary headstock of ordinary description, generally indicated at ||6 (see Figs. l, 5 and 6) and is driven from a variable speed direct current motor ||8 which is carried directly on the head stock bracket |08 to provide a compact and economical driving unit. The head stock motor I|8 is located on the bracket |08 with its axis at right angles to the axis of the head stock. and is connected to the headstock ||6 through driving connections including a worm |20 on the armature Shaft |22 oi' the motor, which meshes with a worm gear |23 on an intermediate shaft |24 supported on the head stock bracket |08 parallel to the axis of the headstock. The headstock is driven from the intermediate shaft |24 by means of a chain belt |26 which passes over a sprocket |28 on the shaft and a similar sprocket |30 mounted integrally to turn with the headstock. With this construction, a uniform and accurate control of the rotational speed of the headstock is obtained by the use of a relatively high speed electric motor combined with the reduction gear unit above described. Any variations in the rotational speed of the headstock which might result from imperfections or play in the cooperating worm and worm gear. are eliminated by the comparatively flexible belt drive from the drive shaft |24 to the head stock.

The workl supporting table is driven from a variable speed reversible direct current motor |32 as best shown in Figs. 2, '7 and 8 of the drawings, through driving connections which comprise a pinion |34 mounted on the armature shaft |36 of the motor to mesh with a gear |38 secured to a rotatable shaft |40. The gear |38 meshes also with a sleeve driving gear |42 which is externally supported in a bearing |46, and has formed at the inner or forward end thereof a clutch face |48 for engagement with a cooperating clutch surface |50 carried on the shiftable element of the power-manual clutch. The shiftable clutch element referred to, takes the form 1| of a shaft |62 supported for axial and rotational movements at one end within the sleeve hub of the gear |42 and at its other end in a bearing |53 on the machine frame. Rigidly secured to the shaft |52 is a high speed driving gear |54 which has formed thereon the clutch face |50. and a slow speed driving gear |56.

In order to provide for the manual operation of the table, there is formed on the end of the shaft |52 a clutch face |60 which is arranged to engage with a clutch member |62 formed on the adjacent end of a hand wheel shaft |64 in axial alignment therewith. The shaft |64 is supported in bearings |66 in the machine frame, and carries at its outer end a table traversing hand Wheel |68. At its inner end the shaft |64 is provided with an axially extending pin which extends into an axial bore in the abutting end of the shaft |62 to maintain the two shafts in axial alignment.

The gears |54 and |56 mesh respectively with gears |14 and |16 which are loosely mounted to turn on a rotatable shaft |18, and form respectively the fast and slow driving elements of. a fast-slow clutch unit. A driven clutch element |80 is splined to the shaft |18 between the driving gears |14 and |16, and is arranged for axial movement in either direction to engage alternatively with cooperating clutch members formed on the adjacent faces of the driving gears. A pinion |82 also secured to the shaft |18 meshes with a gear |84 secured to a drive shaft |86 which also carries the table driving pinion |88, which in turn meshes with a rack |00 formed on the under side of the table. With this construction and arrangement of parts, it will readily be seen that the table may be connected alternatively for power or manual operation by an axial shifting of the power-manual clutch shaft |52 including the gears |54 and |58. The table may\l then be driven selectively at a high or low ratei of speed either by power or manually in accord-f ance with the position of the fast-slow clutch ,l |80 as desired.

The position of the power-manual clutch for the table is controlled from an electrical control system for the machine hereinafter to be described, by means of a solenoid 200 and a clutch actuating lever 202 (see Figs. 7 and 9) which is mounted to turn on a pivot shaft 204, and ls connected at one end to the solenoid armature 208, and at its other end to the axially movable clutch shaft |52. The lever 202 is connected at its upper end to the clutch by means of two bearing blocks 201 which are pivotally supported on the forked upper end of the lever to engage in a peripheral groove formed in the sleeve hub 208 oi' the gear |54 rigidly secured to the clutch shaft |52. At its lower end the clutch lever 202 is connected to the solenoid armature 206 by means of a link 2|0 which is pivotally connected at one end to the armature, and is provided with o reduced portion which extends through a bore formed in a cross pin 2|2 supported in the forked lower end of the clutch lever. A compression spring 2|4 coiled about the reduced portion of the link 2|0 between a collar 2|6 and the cross pin 2|2, tends to maintain the clutch lever 202 yieldlngly against an abutting shoulder on the link 2|0. The movement of the clutch lever 262 in either direction is limited by engagement with adjustable stop pins 2|8 and 220 screw-threaded into the machine casing, and arranged for contact with opposite sides of the lever. Two tension springs 222 connected at one end to the clutch lever 202, and at their other ends to a pin 224

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