US2151660A - Electrically controlled hydraulic wheel feeding mechanism - Google Patents

Description

March 21, 1939.

B. GOEHRING ELECTRICALLY CONTROLLED HYDRAULIC WHEEL- FEEDING MECHANISM Filed April 6, 1938 BERNHARD H. GUEHR/NG Emu-m 45h Iukn 4U Patented alarm PATENT OFFICE mo'rmcmy I ooN'raoLLEn HYDRAULIC V WIIEEL FEEDmG MECHANISM Bernhard H. Goehring, Worcester, Mass, assignor toNorton Company, Worcester, Mass, a cornotation of Massachusetts Application April c, 1938, SerialNo. c0039:

SGIaims.

, The invention relates to grinding machines, and' more particularly toa control mechanism for a hydraulically operated grinding wheel feeding mechanism. 1

One object of the invention is to provide a simelectrically controlled wheel feeding mechanism for a grinding machine. Another'obiect of the invention is to provide a suitable wheel feed con-v 19 trolling mechanism so that the infeeding movement of the grinding wheel may be precisely controlled to grind successive work pieces to a predetermined size. Another object of the invention is to provide a fluid pressure operated electrically controlled wheel feed control which enables a precise regulation of the infeeding movement and also the dwell after the infeeding' movement has stopped. A further object of the invention is to provide a wheel feeding mechanism having an electrical time delay relay which serves to control the infeeding cycle'of the grinding wheel, that is, it is rendered operative when the grinding wheel infeed is initiated and is arranged to time the entire infeeding movement, not only the rapid approach but also the grinding speed and dwell, after which it serves rapidly to withdraw the grinding wheel to an inoperative position. Other objects will be in-part obvious or in part pointed out hereinafter.

vThe invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and

the scopeof the application of which will be in- 35 dicated in the following claims. In the accompanying drawing in which is shown one of various possible embodiments of the f mechanical features of this invention,

Fig. 1 is an end elevation of a grinding machine having parts broken away and shown in section .combined'with a wiring diagram more clearly to show the operating construction; and

Fig. 2 is an electrical diagram of the time delay relay showing thecontrol switches. A grinding machine has been illustrated in the mounted on transversely extending ways (not shown) on the base Ill. The wheel slide ll supl3. The wheel spindle l3.may be driven by any of the well known mechanisms, such as an overhead belt drive or an electric motor' l6 mounted on the wheel slide. As illustrated, a

ple, thoroughly practical hydraulically operated drawing comprising abase III which supports a transversely movable wheel slide II which is ports a rotatable grinding wheel I: which is mounted on the end of a rotatable wheel spindle wheel driving pulley II is mounted on the opposite end of the wheel spindle I3 and is connected by a driving belt IS with a pulley on the electric motor l6.

. The base I II also supports a longitudinally movable .work table I! which is arranged to reciprocate longitudinally relative to thebase III on a flat way l8 and a V-way IS. The table II is provided with a rotatable work support including a headstock 20 and a rootstock (not shown) each of which is provided with work supporting centers rotatably to support a work piece 2| in operative relation with the grinding wheel l2. The table I! may be traversed longitudinally by a .manually operable traverse mechanism which in cludes a rack bar 25 depending from the under side of-the table [1. The rack bar 25 meshes with a gear 26 mounted on the inner end of a rotatable shaft 21. A manually operable traverse wheel 28 is mountedjon the outer end of the shaft 21 and is arranged to be manually rotated to traverse the table ll longitudinally relative to the base ID. If desired, a power operated table traversing or reciprocating mechanism may be provided, such as for example a mechanism of the type .shown in the expired United States patent to Norton No. 762,838 dated June 14, 1904.

A wheel feeding mechanism is provided for manually feeding the grinding wheel toward and from the work,' which comprises a half nut depending from the wheel slide II. The half nut 35 meshes with or engages a rotatable cross feed screw 36 A forwardly extending portion 31 of the cross feed screw 36 is slidably keyed to a rotatable sleeve 38. The rotatable sleeve 38 .is formed as an integral part of a rotatable shaft which is mounted in bearings 39 and 40 in the base ID. A manually operable feed wheel 4| is mounted on the outer end of a stud 42. The stud 42 carries a pinion 43 which meshes with a gear 44 mounted on'the outer end of a sleeve shaft 38 so that a manual rotation 'of the feed wheel 4| serves to rotate the feed screw 36 in either direction to cause .a forward or rearward feeding movement of the grinding wheel l2 and the wheel slide II. The wheel feed 4| may be provided with a micrometer adjusting mechanism 45 which is substantially identical with that shown in the abovernentioned prior United States patent to Norton. This micrometer mechanism serves precisely to adjust a stop abutment relative to the manually operable infeed 'wheel to compensate.for wheel" wear.

In the preferred construction the wheel slide H is arranged so that it may be moved toward and from the work piece U to grindthe same to a predetermined size by means of a fluid pressure actuated wheel feeding mechanism. As

' illustrated in the drawing, the rear end of the I a u fastened to feed screw 96 is rotatably supported in a slidably keyed bearing 66 which is supported in a casing II on the base of the machine. A fluid pressure cylinder 49' is attached to the casing 6| and contains a slidably mounted piston 62 which is connected by a piston rod 69 with the bearing 66 and is arranged so that whenfluld under pressure is admitted toa cylinder chamber 64, the

piston 62 will be moved toward the right into its rearward position, as illustrated in the drawing, transmitting a corresponding movement through the feed screw 66, the half nut 96, to move the wheel-slide II and the grinding wheel I2 rearwardly to an inoperative position. Similarly, when fluid under pressure is admitted to the cylinder chamber 64 or the cylinder chamber 66, a rapid approaching or receding movement of the grinding wheel I2 and wheel slide II is provided.

A fluid pressure system is provided to supply fluid under pressure for moving the piston 62 so as to cause an infeeding or outfeeding movement of the grinding wheel I2. This system may comprise a reservoir 66 which is formed as a box-like section within the base I6 and serves to convey fluid through a pipe 6| to a fluid pressurepump o62. The pump 62 forces fluid under pressure through a pipe 69, to a control valve 64. The

control valve 64 is preferably a piston type valvecomprising a valve stem 66 having formed integrally therewith valve pistons 66, 61, 66 and 69. Fluid under pressure passing through the pipe 69 enters a valve chamber 16 located between the valve pistons "and 66 and passes through a passage 12, into the cylinder chamber 64, to move the piston 62 to its rearward position with the grinding wheel I2 separated from the work piece 2|, as indicated in the drawing. During the rearward movement of the piston 62 toward theright, fluid is exhausted from the cylinder chamber 66,

through a passage 16, into a valve chamber 11.

ydr 66. e

The valve stem 66 is arranged so that it may be moved endwise to shift the valve 64 into a reverse position so as to cause either a forward or. rearward feeding movement of the grinding wheel I2. In the preferred construction a spring 96 is provided to maintain the valve 64 normally in its right-hand end position to cause the piston 62 and wheel slide -II and grinding wheel I2 to remain in their rearmost position. A solenoid 6I mounted on the base I6 is provided to shift the .valve 64 toward the left to cause a forward feeding movement of the grinding wheel I2 when. desired. The solenoid 6| is connectedby a link 62 with a stud "supported at the lower end of a rock arm 64., Th ockarm. 64 is pivotally supported by a stud 66 hich is supported by a bracke' I6 of the machine. The upper end of the rock arm 64' is provided with a stud 61 which rides within an annular groove formed In a spool-shaped member 66 supported on the left-hand endof the valve stem 66.

feeding movement of the grinding wheel I2. In

the preferred construction'a self-contained dash pot feed regulator'is provided comprising a pair of dash pot cylinders 96 and 91 which contain dash pot pistons 96 and 99, respectively. The dash pot pistons 96 and 99 and their respective cylinders 96 and 91 arearranged with their axes parallelto each other and spaced on diametrically opposite sides of the piston rod 63. The dash. pot pistons 96 and 99 are normally held ina rearward (right-hand) position by means of springs I66 and MI, respectively. An adjustable stop screw I62 serves to limit the rearward movement of the dash pot pistons 96 and 99, respectively. A slidable sleeve I66 is supported on the rear extension 66' of the piston rod .53. The sleeve I63 has a flanged portion I 64 which is either formed integral therewith or fixedly secured thereto. The flange I64 is arranged to engage the right-hand end faces of the dash pot -69 engages the righthand end of the sleeve I69.

Continued movement of the piston rod 66a moves the sleeve I66 and the flange I64 toward the left and continued movement serves to move the dash pot pistons 96 and 99 in a direction toward the left. When the flange I 64 engages the ends of the dash pot pistons 96 and 99, respectively, the rapid approaching or feeding movement of the grindingwheel I2 toward the work piece 2|, as produced by the piston 62, is reduced to a slower predetermined grinding feed due-t the fact that fluid confined within the dash pot cylinders 96 and 91, respectively, which are interconnected,. exhausts through a passage I61, a needle valve I69, through a pipe I69, into a reservoir II6. By adjusting the aperture of the needle valve I66, a desired and predetermined infeeding movement of the grinding wheel I2 may be obtained.

when fluid under pressure is admitted to the cylinder chamber 64 to cause a rearward move.- ment of thepiston 62, the sleeve I69 together with the flange I64, is moved rearwardly by means of the released compression of the springs I66 and "I which returns the dash pot pistons 96 and 99, respectively, totheir rearward positions and moves the flange I64 and its supporting sleeve I66 toward the right until the flange I64 engages the adjustable stop screw I62. During the rearwardmovement of the dash pot pistons 96 and 99, asuction is created within the dash' pot cylinders 96 and '91, respectively, which serves to aid in drawing fluid from the reservoir II6, through a pipe II I, and a ball check valve II2, to flll the dash pot cylinder chambers 96 and 91-for' the next infeeding movement of the grinding wheel I2. During the infeeding movement of the d dash pot pistons 96 and ",fluid within the dash pct cylinders 96 and 91serves to',hold the balk,

check valve I I2 closed so that fluid. within the dash pot cylinders 96 and 61 is forced out through the passage I61 and the needle valve I66, into the reservoir III, to control the rate of the infeeding movement, 'as' desired. An adjustable throttle valve H1 is provided to facilitate theexhaust of fluid from the dash pot chambers 96 and 91 after the port or passage 161 is closed'by the piston 96. If desired, the throttle valve I I 1 may be used to give a very fine flnal feed just prior to the stop II9 engaging itsstop surface II4. In the latter case two distinct feeds of the wheel could be obtained, one feed by manipulationof the I valve I08 combined with the opening of the valve adjustable stop collar H3 carried by the sleeve I03 engages a fixed stop surface H4 on the rear face of the dash pot cylinder head. A pair of lock collars H5 serve to position the stop collar H3 and to lock the same in adjusted position.

A throttlevalve H6 is located in the pipeline I8 and serves to control the exhaust of fluid from the cylinder 49 so as to regulate the speed of movement of the grinding wheel I2 and its supporting wheel slide I I during .the rapidapproaching or positioning movement thereof.

In order to obtain one object of the invention itis desirable to provide a suitable control mechanism for the wheel feeding mechanism which is arranged so that when a work piece has been inserted in the machine, it is merely necessary for a ntrol lever to be shifted to initiate an approaching movement'of the grinding wheel which continues until the grinding wheel approaches the work piece, after which the approaching speed is reduced to a predetermined grinding speed. The infeeding continues until the stop H3 engages the stop surface H4 and positively limits the infeeding movement of the videdfor the electrical control system from'a source of power, asindicated by the power linesv I In the preferred construction, the 'time delay relay I20 is so connectedas to regulate and control the shifting movement'of the main control I or feed control valve 64 so as to control the entire infeeding movement of the grindingwheel I2, namely to control the over-all cycle including the rapid approaching movement of I the grind-' ing wheel I2, the slower grinding infeed of the wheel, and the dwell which occurs thereafter before the grinding wheel is removed to its rearward or inoperative position. A pair of push button switches I22 and I23 are mounted on the front wall of the machine base ID. The push buttons I22 and I23 are arranged to be actuated by a control lever I24 which is pivotally supported on a stud I25 w ch is fixedly supported on the base I0 of the machine. The button I22, when pushed, is arranged to cause a rearward feeding. movement of the grinding wheel I2 and its supportingslide II and the push button I23,

when actuated, servesto start the grinding cycle.

. The control lever I24 is normally held in acentral or inoperative position by means of the spring-pressed plunger I21 on the lover I 24 engaging a V.-shaped-no.tch I28 formed in the lever supporting bracket, as shown. The springpressed plunger I21 and .the V-shaped notch I28 are so shaped and arranged that when the lever I24 is moved either in a counterclockwise direction to initiate an infeeding movement or of the spring-pressed plunger I21 acting upon the V-shaped notch I28 as 'soon as the operator releases his grasp on the lever I24.

The time delay relay I20 is one of the standard electricallyoperated adjustable time delay relays, such as that known as the -Microflex"- ing or opening of the timer control circuit to' initiate a cycle of operation. This timer is diagrammatically illustrated in Fig. 2 ofthe drawing. In the normal position, as illustrated in the diagram, no-current is-applied to the timer; allthree contacts are open. The cycle is initiated by momentarily closing the switch I23 of the timer control circuit. When the control circuit is closed, contacts T and #2 close, contact #1 remains open, and the timing cycle starts. When the timing interval terminates, contacts T and #2 open, thereby breaking the circuit and deenergizing the solenoid III which releases the compression of the spring 80' to reverse the control valve 64 and cause a rearward movement of the wheel slide II and the grinding wheel I2. The timer. automatically resets for the next grinding cycle. If for any reason it is desired to stop grinding during a grinding cycle, the lever I24 is moved in a clockwise direction (Fig. 1)

instantaneously to open the push button switch I22 which opens a circuit to interrupt the time delay relay and cause the grinding wheel to move to a rearward position.

The time delay relay may --be adjusted to con mentof the grinding wheel, that is, the rapid appreach, grinding feed and dwell. The relay I20 allows a certain time interval to elapse'a'fter the push button I23 is actuated to initiate the forward movement of the grinding wheel I2 and to control the dwell thereafter so as to grind the work piece 2I to the desired and predetermined size. The time delay relay I 20 is so connected with the push buttons I22- and I23 and also with the solenoid III that when the lever I24 is 'trol the entire approaching and. infeeding move- 1 rocked in a counterclockwise direction to start a grinding cycle, the push button switch I23 is actuated to start the time delay relay I20 functioning and at the same time energizes the solenoid BI which serves to shift the control valve 64 toward the left against the compression of the spring 80 to-admit fluid'under pressure from the pipe 63 through the passage I6, into the approach the work piece 2 I at a rate governed by the throttle valve 6 located in the exhaust pipe line I8. The rapid approaching movement ofthe grinding wheel I2 and its supporting slide II continues until the sleeve I03 and its flange I cylinder chamber 55, to cause the grinding wheel I2 and its supporting slide II rapidly to m4 engagethe dash pot pistons 93 and 99, re-

spectively, after which ithe rapid approaching movement caused by the fluid pressure operated pistpn 52 is slowed down to a slow uniform reservoir mi. The slow grinding infeed continues until the adjustable stop I I3 engages the stop surface 4 which positively limits the grinding infeed and allows the grinding wheel I2 to remain in grinding contact with the work piece 2| to finish grind the work.

After apredetermined time interval has elapsed accordingto the adiustment of the time delay relay I20, the solenoidfll is automatically dc- :energi'zed, thereby. releasing the compressed spring 80 which returns the control valve 64 into the position illustrated in the drawing so that fluid under pressure passing through the pipe 68 passes through a passage 12 into the cylinder chamber 54 to cause the wheel slide II and grinding wheel l2 to move rapidly totheir rearward or inoperative position.

The push button I22 is providedso that if for any reason it is desirable to interrupt the grinding cycleand cause the. grinding wheel I2 to move rearwardly without completing its cycle,

I the lever I24 may at any time during the grinding cycle be moved in a clockwise direction to operate the push button switch I22 which serves through the time delay relay I28 to deenergize the solenoid 8i and thus allow the released compression of the spring 80' to shift the valve 64.

into the position shown in the drawing so that the grinding wheel I2 will move rapidly to its rearmost inoperative position.

I The operation of this wheel feeding mechanism will be readily apparent from the foregoing disclosure. Assuming the various valves and other parts to have been previously adjusted to the desired positions for producing a predetermined grinding cycle, the lever 'I 24 is moved in a counterclockwise direction to actuate the push button switch I28 which serves to set the time delay relay I20 in operation and at the same time energizes the solenoid 8| to-initiate a forward movement of the 'grinding wheel I2 and wheel slide II. The

approaching movement of the wheel continues first at a rapid rate as determined by the piston 52 and is thereafter slowed down to a grinding feed by means of the dash pot pistons 98 and 88 which continues until the stop III engages the fixed stop surface H4 to prevent further approaching, movement of the wheel toward the work piece 2| The wheel remains in grinding contact with the work for a period of dwell to finish grind the work piece, after which the time delay: relay operates to deenergize the solenoid 8 I thereby releasing the tension of the spring 88 which moves the control valve 64 toward the right to initiate a rearward feeding movement of the grinding wheel. It will be readily apparent that the time delay relay I28 controls the duration of the approaching movement of the wheel and also the period of 'dwell which follows it. By ad iusting the valves IIO, valves I88 and Ill, the approaching and grinding feed of the wheel may be independently adjusted, and by manipulation of the time delay relay the over-all cycle, that is, the approaching and grinding feeds plus the period of dwell, may also be adjusted so that the entire cycle is under a definite time control.

It may be desirable for certain grinding operations to cut out the automaticcycle control and control the forward and rearward feeding movements of the grinding whee-l ,I2 manually. This may be accomplished by placing a snap switch It; in the electrical circuit. n it is desired' to operate the wheel I2 under the control of the manually operable lever I24, the snap switch I28 is opened, thus rendering the time relay inoperative. In this condition of the electrical circuit, movement of the lever I24 in a counterclockwise direction operates the push button I23 to energize the solenoid 8| to initiate a forward approaching movement of the grinding wheel I 2, Similarly, when the lever I24 is moved in a clockwise direction to operate the push button switch I22, the circuit is broken, thereby deenergizing solenoid 8 I, which serves through the released compression of the spring 88 to shift the control valve 64 into its 3 reverse position to cause the grinding wheel I2 and its supporting slide II to move to a rearward position.

It will thus be seenthat there has been provided by this invention apparatus in which the various 3 objects hereinabove set forthtogether with many for, means including a solenoid to actuate said valve, said solenoid when energized serving to actuate said valve to cause an infeeding movement of said slide and serving when deenergized to cause a rearward feeding movement of said slide, and means including an electrical time delay relay to energize said solenoid to start a grinding cycle and to deenergize said solenoid after a predetermined time interval to stop the grinding cycle, said time delay relay serving to control the approaching, grinding infeed and rearward I I movement of the grinding wheel.

2. In a grinding machine, a rotatable grinding wheel, a transversely movable slide therefor, a fluid operated piston and cylinder operatively connected to move said slide, a control valve therefor, means including a solenoid to actuate said valve, said solenoid when energized serving to actuate said valve to cause an infeeding move- "ment of said slide and serving when deenergized' to cause a rearward feeding movement of said slide, means including an electrical time delay relay to energize said solenoid to start a grinding cycle and to deenergize said solenoid after it predetermined time interval to stop the grinding cycle, and an electric switch to start said time delay relay in operation, said time delay relayserving to control the approaching, grinding infeed and rearward movement of the grinding wheel.

3. In a grinding machine, a rotatable grinding wheel, a transversely movable 'slide therefor, a fluid operated piston and cylinder operatively connected to move said slide, a control valve therefor,

means including a solenoid to actuate said valve,

said solenoid when energized serving to actuate said valve to cause an infeeding movement of said slide and serving when deenergized to cause a rearward feeding movement of said slide, means including an electrical time delay relay to energize said solenoid to start a grinding cycle and to deenergize said solenoid after a predetermined time- 'interval to stop the grinding cycle, an electric switch to start saidtime delay relay in operation and to energize said solenoid, and a manually operable lever to actuate said switch to start a aloaeeo I a grinding cycle, said time delay ,relay serving to control the entire movement of the grinding wheel toward and from thework piece. a

4. In a grinding machine, arotatable grinding wheel, "a transversely movable slide therefor, a fluid operated piston and cylinder operatively connected to move said slide, a control valve therea for, means including a solenoid "to-actuate said relay to energize said solenoid to start a grinding cycle and to deenergize said solenoid after a predetermined time interval, an electric switch to start said time delay relay in operation, an electric switch to interrupt said time delay relay at any I y time during the grinding cycle, and a manually 2o operable lever to actuate either of jsaid switches.

Ihimifldihg machine, a rotatable I wheel, a transversely movable slide therefor, a

fluid operated piston and cylinder operatively connected to move said slide, a control valve therefor,

means including asolenoid to actuate said valve, saidsolenoid when-energized serving to actuate said valve to cause infeeding movementv of said slide and serving when deenergized to cause a rearward -feeding movenient'ot said slide,means including an electrical time delay relay to energizesaid solenoid to start a grinding cycle and to desaid solenoid after a predetermined time interval, an electric switch to start said time delay relay in operation, an electric switch to interrupt i aid time delay relay at any time during the grind ingj cycle, a manually operable lever to actuate either of said switches, and means including aspring-pressed plunger normally to maintain said lever in an inoperative or central position.

BERNEARDEGQEHRING. 20

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