US2214394A - Hydraulic table reciprocating mechanism - Google Patents

Description

Sept. 10, 1940. w. H. WOOD HYDRAULIC TABLE RECIPROCATING MECHANISM 2 Sheets-Sheet 1 Filed May 26, 1938 gwucmk o WHLLHCEH. W000 4M A warm Sept. 10, 194o. A H WOOD 2,214,394

HYDRAULIC TABLE RECIPROCATING MECHANISM Filed llay 26, 1958 2 Sheets-Sheet 2 Figb ' WHL LFICE H.Wucm

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ratentease t. 16, 1940 UNITED STATES- PATENT OFFICE HYDRAULIC TABLE REOIPROCATING CHANISM Wallace H. -Wood, Worcester, Mass, assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts Application May 26, 1938, Serial No. 210,213

6 Claims.

The invention relates to grinding machines, and

more particularly to an hydraulically operated ends of the table reciprocation. A further object. I

of the invention is to provide an hydraulically controlled dwell control for the table traversing mechanism. A further object of the invention is to provide an hydraulically operated table reciprocating mechanism with an hydraulically operated time delay control therefor to control the extent of dwell at each end of the table stroke. Other objects will be in part obvious or in part pointed out hereinafter.

' The invention accordingly consists in the features of construction, combinations of elements,

bracket l6, to the hollow piston rod l4 and piston and arrangementsof parts; as will be exemplified in the structure to .be hereinafter described, and the scope of the application of which will be indicated in the following claims. V

In the accompanying drawings, in which is shown one of various possible embodiments.v of the mechanical features of this invention,

.Fig. 1 is an hydraulic diagram of the improved table reciprocating mechanism and dwell control device therefor;

Fig. 2 is a cross sectional view through the table reciprocating mechanism, showing the actuating valve in cross section;

Fig. 3 is a longitudinal'sectional view, on an enlarged scale, taken approximately on the line 3-3 of Fig. 2; and

- Fig. 4 is a sectional view taken approximately on the line 4-4 of Fig. 3. i

'.As illustrated in the drawings, a grinding ma-' chine embodying this invention may comprise a base 9 which supports a longitudinally reciprocable work table Ill on the usual V-way-and flat way (not shown) fora longitudinal reciprocating movement relative to thebase 9.

A fluid pressure operated reciprocating mechanism is provided to reciprocate the work table l j comprising a fluid pressure cylinder H which is fixedly mounted on the under side of the table I0.

' The cylinder ll contains a pair of spaced pistons I2 and I3 which are connected by a pair of -hollow piston rods I4 and I5, respectively, with a pair of hollow brackets I6 and I1, respectively, which are fixedly mounted on'opposite ends of the base 9.

In the preferred construction, the base 9 is formed with a box-like construction in which the lower portion thereof serves as a reservoir 20 for the fluid pressure system. Fluid is drawn from the reservoir through a pipe 2| by a motor driven fluid pressure pump 22 and is forced through a pipe 23 and a pipe or passage 24 to a table control valve 25. A fluid pressure relief valve 26 is provided in the pipe line 23 and is arranged to allow excess fluid under pressure to .by-pass through apipe 21 to the reservoir in casethe 1! pressure within the'hydraulic system increases above a desired predetermined pressure. I

The control valve 261s preferably of a balanced piston type reversing valve which includes a movable valve member 29 having formed integrally 20 therewith a plurality of valve pistons 30, 3!, 32, 33 and. Fluid under pressure from the pump 22 is forced through the pipe 23and the pipe or passage 24 into a valve chamber 31 located between the valve pistons through a pipe 39, into an aperture 40 in the i2, into a cylinder chamber 4| to cause the cylinder Hand tabledll to move in a direction toward the left, (Fig. 1). During movement of the table .3 I0 towardth'e left, fluid within a cylinder cham- I ber 42 is exhausted through the piston, l3, the hollow piston rod l5, and an aperture 43 within the bracket l1, and through a pipe 44 into a valve chamber 38 located between the valve pistons 32 and 33, and out through a pipe 45 which returns exhaust fluid through a pipe 46 into the reservoir 20. A speed control valve 50, as illustrated in the drawings, is preferably formed integral with the valve "25. As illustrated diagrammatically in Fig. 1, the valve 50 is shown as a separate valve unit;

The valve 50 is preferably located in the exhaust side of the fluid pressure system so as to main: tain a uniform fluid pressure on the operative side of the main cylinder and thereby produce a more uniform table movement. This valve comprises a valve stem 5| which is provided with integrally formed valve pistons 62 and 53. The casing for r the valve is provided with a V-shaped port 54 50 which is located at one end of the pipe line or passage 45, conveying fluid from either the valve chamber 31 or 38,'depending upon the position ofthe valve 25. The passage or .outlet pipe 46 serves to exhaust fluid from a throttle valve 55 3| and 32, and passes out 25 chamber 51, into the reservoir 20 within the base 9 of the machine. v

The throttle valve 50 is arranged so that it maybe moved longitudinally from a full .line position to a dotted line position. The valve is provided with an actuating knob 59 on the front end of the valve stem 5|, which permits the valves to be rotated. In the preferred construction, the end of the valve piston 53, instead of being a plane surface at right angles to the axis of the throttle valve, is arranged at an angle thereto. By providing an angularly positioned end face to the piston 53, any rotation of the valve member serves as a fine adjustment to cut off more or less of the V-port precisely to regulate the exhaust of fluid from the system and thereby permit a fine regulation of the table speed.

In order that the piston 53 may .be maintained in the desired adjusted position so as to enable the table to be stopped and started as desired without changing the feed adjustment, a serrated or notched portion 60 is provided which is formed integral with the valve stem 5|, and a spring pressed pawl 6| is carried by the valve casing 50, so that when the knob 59 is rotated to adjust the valve piston 53 to give the desired table speed, the pawl 6| engages notches in the serrated portion 60 and serves to hold the valve piston in its adjusted position so as to permit longitudinal and axial movement of the valve stem 5| by means of a control lever 70 to stop and start the table movement without upsetting the speed adjustment of the valve. The control lever 10 is pivotally mounted on a. stud II which is fixedly supported relative to the base 9 and serves to permit a rapid movement of the valve stem 5| to stop and start the table movement. The lever 10 is provided with an aperture 12 fitting loosely around a sleeve 13 which is mounted on the valve stem 5|, Trunnion pins 14 are provided on diametrically opposite sides of the aperture 12 on the lever 10 and are arranged to engage vertical .slots 15 in the sleeve "I2. It will be readily apparent from the foregoing disclosure that when the throttle valve lever 10 is in the I0, it is desirable to provide a suitable fluidbypass whereby the fluid may readily pass from the cylinder chamber 4| at one end of the cylinder II tot-he cylinder chamber 42 at the other end thereof to facilitate a manual traverse of the .table. In the preferred construction, a. pipe or passage is provided to connect-the pipe 44 and the valve chamber 38 with a pipe or passage 8| provided as an extension of the pipe 39. When the throttle valve 50 is in the closed position, as indicated in broken lines, fluid may readily pass from the cylinder chamber 4|, through the pipe 39, the pipe 8|, through a valve chamber 82 located between the valve pistons 52 and 53, through the pipe 80, through the pipe 44, into the cylinder chamber 42. Thisby-pass in the throttle valve interconnects the.cylinder chambers 4| and 42 so that when the fluid pressure system is shut off by closing the throttle valve 50, the table I0" may bereadily traversed manually. when desired.

'pressure entering the chamber A manually operative table traverse mechanism may be of the type shown in my prior United States Patent No. 2,071,677 and may consist of a manually operable hand wheel and a rack and gear mechanism for moving the table longitudinally.

A suitable reversing mechanism is provided to change the direction of movement of the table I I as desired. In the preferred construction, the adjustable table dogs and 9| are adjustably mounted in a T-slot 92 formed in the front edge of the table I0. The dogs 90 and 9| are arranged to engage a stud 89 mounted on the upper end of a reverse control lever 93 which is pivotally mounted on.the forward'end of a rock shaft 94' which is rotatably supported in the base 9 of the machine. The lever 93 is operatively connected to move the valve stem 29.

In order that the table may be, reversed with a minimum amount of vibration, it is desirable to provide a lost motion connection between the reversing. lever 93 and the reversing valve 25, so that during the initial movement of the reverse lever under the influence of the table dogs 90 and 9|, the valve is not moved. This mechanism preferably comprises a short lever 95 which is fixedly keyed to the inner end of the rock shaft 94. A similar short lever 96 is rotatably mounted on the rock shaft 94 and is supported thereon by means of a bushing, so that the lever 96 is free to oscillate relative to the shaft 94. The lever 96 carries a stud 91 which engages a groove 98 formed in an extended portion of the valve stem 29. The lever 95 is provided with an aperture 99. A pin I00 is fixedly mounted on the lever 96 and projects within the aperture 99 in the lever 95.

The lower ends of the lever 95 and 96 are provided with enlarged end portions I M and I02, respectively, each of which is provided with a semi-cylindrical aperture I03 and I04, respectively. A spring I05 is provided within the semicylindrical apertures I03 and I04 and serves to hold the levers normally in a definite aligned relationship to each other.

Assuming the ,parts of the reversing mechanism to be in the positions illustrated in Fig. 1, the table is moving in the direction toward the left, which movement continues until the reversing lever 93 is moved a suflicient distance in a counterclockwise direction to actuate the lever '95 through its lost motion movement until the aperture 99 engages the pin I00. This movement of the lever 95 relative to the lever 96 serves to compress the spring I05 and when the aperture 99 engages the pin I00, continued movement of the table serves to throw the reversing valve stem 29 into a central or neutral position, as indicated in Fig. 3, in which position the pressures are balanced on opposite sides of the main cylinder II. The compression of the spring I05 tends to move the valve stem 29 toward the right (Fig; 3), whichmovement is prevented by means to be hereinafter described,

When the compression of the spring I05 is released, it serves to-shift the valve from a central or neutral position so as to uncover a port III, decreasing the fluid pressure passing into a chamber H2 and increasing fluid under pressure passing into a valve chamber II3. It should be noted that the valve pistons 30 and 3| are of different cross sectional area, and fluid under II3 serves, through the differential piston area on the pistons 30 and 3| to move the valve stem 29 toward the right, as viewed in Fig. 3, to move the valve 65 is preferably a piston type valve, which is normally held in an open position by means of a valve chambers I I3 and H2 function as a pilot valve to cause a reversal of the reversing valve 1 under the influence of fluid under pressure. The reverse lever 93 serves only to cause the reverse valve to move to a central or neutral position, as

illustrated inFig. 3, and the spring I05 then being under compression, serves to move the reverse valve slightly off center to change the respective openings of the ports H0 and III and cause fluid under pressure to operate through the valve chambers H2 and H3 to cause a fluid pressure reversal of thereversing valve, thereby combining the functions of a reversing valve and a pilot valve in a single valve unit and thereby eliminating the piping connections and losses due to passages between the various valves as experi-.

enced heretofore.

Fluid within the valve chamber II2 may exhaust through aport I20 andsimilarly, fluid within the valve chamber II3 may exhaust through a port I2I, into reservoirs I22 and I23, respectively. When the valve piston 29 is moved I to either end of its stroke, as shown in the diae grammatic illustration in Fig. 1, fluid within the chamber H3 is free to'exhaust through port I2I, a pipe I24, and through a pipe l25, into the reservoir 20. Similarly, when the valve stem 29 is moved toward the right, fluid within the valve chamber 2 mayexhaust through the port I20,

a pipe I26, and a pipe I21, into the reservoir 20.

In a. cylindrical grinding machine, it is frequently desirable to provide a sufficient dwell of the table at the .end of its reciprocatory stroke so that the workpiece may rotate at least one complete rotation before the table stops its movement in one direction and starts its movement in the reverse direction. The period of dwell necessary'to accomplish this result varies with the size of the work being ground, the width of the wheel being used,'as well as the speed of work rotation and table reciprocation. It is, therefore, desirable to provide a variable dwell at either or both ends of the table stroke toaccomplish the desired results. In the preferred construction, the dwell at the end of the table stroke 'may be accomplished by interrupting the reversal in movement of the control valve and allowing it to dwell in a central or neutral position for a predetermined adjustable time interval.

In the preferred construction an hydraulically operated control vmechanism is provided to control the delayed action of the reversing valve so that thetable dwell at ,either or both ends of the table stroke may be varied as desired. This is preferably accomplished by providing a cut-oil valve I30 'between the pipes I24 and I25. The valve I30 spring I3I, allowing free passage of fluid from the pipe I24, through a valve chamber I32, into the pipe I25. The ,valve I30 [is arranged so that it may be automatically closed by introducing fluid under pressure into a cylinder chamber I33 which serves to raise the valve pistons I34 and.

I35 to close the port'at the end of the pipe I24 and preventpassage of fluid therethrough. The

admission of fluid to the chamber I33 is preferably controlled by a control valve I35 which is preferably a piston type valve comprising a valve stem I36 having formed integrally therewith valve pistons I31 and I36. The valve stem I36 together with the valve pistons I31 and I38 are normally held in an uppermost position by means of a spring I39. The valve I35 is preferably actuated in timed relation with the movement of the table I0.

A bell crank lever I40 is pivotally mounted on a stud I4I on the base 9. A horizontally extending arm I42 of the bellcrank I40 is arranged to engage the upper end of the valve stem I36. Anupwardly extending arm I43 of the bell crank I40 is arranged in the path of an adjustable dog I44 which is adjustably secured to the under side of the table reversing dogs 90. When the table moves to the,right, so that the dog I44 engages, the arm I43 of the bell crank I40 and rocks it in a clockwise direction, thus causing a do ward movement of the valve stem I36, it ser es to open a port so that fluid under pressure may flow from the pipe I24, through a pipe I45, into a valve chamber I46 formed between the valve pistons I31 and I38, and out through a pipe I41, into the cylinder chamber I33, to move the valve pistons I34 and I35 upwardly against the compression of the spring I3I, thus cutting off the flow of fl'uid between the pipes I24 and I25.

As soon as the dog I44 passes over the high point of the lever I43, the released compression of the spring I39 returns the valve stem I36 and the'valve pistons I31 and I38 into the position shown'in, Fig. 1, thereby. again cutting off the flow of fluid under pressure to the cylinder cham-- ber I33. A pipe I50 controls the exhaust of fluid from the cylinder chamber I33. An adjustable needle valve I5 I in the pipe line I50 serves to regulate the rate of exhaust of fluid therefrom and thereby regulates the time interval necessary for. the valve pistons I 34 and I35 to drop into the position shown in- Fig. 1 so as to allow the passage of fluid from the pipe I24 into the pipe I25, and thereby permit the reversing valve stem 29 to shift under the influence of fluid under pressure into the reverse'position, thereby changing the direction of movement of the table- Similarly, a cut-off valve I of the piston type is provided which is normally held open by means of a spring I6I sothat fluid passing through the pipe I26 may pass directly through avalve chamber I62, into the pipe I21, and return to the reservoir 20. The valve I60 comprises a. pair of valve pistons I64 and I forming the valve chamber I62 therebetween. A control valve I65 is provided for controlling the admission of fluid under pressure to a'cylinder chamber I63 so as to raise the pistons I64 and I65 to close the port at theend of the pipe I26 and thereby prevent the passage or fluid from the pipe I26 into the pipe I21. The valve I65 comprises a valve piston 1 I66 having formed integrally therewith valve pistons I61 and I68. A spring I69 normally tends to hold the valve stem I66 together with the valve pistons I61 and I68 in an uppermost position- (Fig. 1). In order that the valve may be opened in timed relation with the table movement, a

.bell crank lever I10 is pivotally mountedon a stud III which is fixedly supported on the base 9. A horizontally extending arm I12 of the bell crank I10 engages the valve piston I66. An upwardly extending arm I13 of the bell crank I10.

is arranged in the path of an adjustable dog member I14 adjustably supported on the under side of the table reversing dog 9|. When the table I moves toward the left (Fig. 1) the dog I14 engages the arm I13 which serves to rock the bell crank I10 in a counterclockwise direction to cause a downward movement of the valve stem I66, thereby permitting fluid under pressure to pass from the pipe 24 through a pipe I15 and a valve chamber I16 located between the valve pistons I61 and I68, into a pipe I11 which admits fluid under pressure to the cylinder chamber I53. v

The admission of fluid under pressure to the cylinder chamber I63 causes an upward movement of the valve pistons I64 and I65 against the compression of the spring I6I. As soon as the dog I14 rides over the end of the bell crank lever I13, the released compression of the spring I69 moves the valve stem E56 upwardlyto block off the port at the end of the fluid pressure pipe I15 and thus prevent further passage of fluid to the cylinder chamber I63. The released compression of the spring I6I then tends to force fluid from the cylinder chamber I63, through a pipe I80, into the reservoir 20. An adjustable needle valve I8I serves to throttle the exhaust of fluid from the chamber I63 and thereby serves to control the downward movement of the valve pistons I64 and I65 and thus determines the time interval or period of dwell. When the valve pistons I64 and I65 have been moved downwardly into the position illustrated in Fig. 1, fluid under pressure may then pass from the pipe I26, through the valve chamber I62, and the pipe I21, which returns to the reservoir 20, thus al-v lowing the reversing valve to be shifted into a reverse position under the influence of fluid under pressure.

The operation of this table reciprocating mechanism will be readily apparent from the foregoing disclosure. Assuming all of the parts of the machine to have been previously adjusted and the table I0 is traversed in the direction of the arrow, namely toward the left (Fig. 1), this movement continues untilthe projection I90 of the table dog 9I engages the stud 89 on the reverse lever 93. Just before the projection I90 of the dog 9| engages the pin 89, on the reverse lever 93, the dog I14 engages the arm I13 of the bell crank lever I10 and causes a downward movement of the valve .stem I66 which serves to admit fluid under pressure to the cylinder chamber I63. This in turn causes an upward movement of the pistons I64 and I65 to cut off 1 the flow of fluid between the pipes I26 and I21.

The reversing lever shifts the valve 25 to a central or neutral position, such as shown in Fig. 3,

and at the same time compresses the spring I so that the spring tends to throw the valve slightly beyond a central position. 7

The reversing lever throws the valve stem 29 to a central position in which position fluid passing through the pipe 24, as shown in Fig. 3, may enter both the valve chambers 31 and 38 and pass through the ports H0 and III, into valve chambers H2 and H3. The valve I30 being open, fluid entering the valve chamber I I 3 may pass through the'pipe I24 and valve chamber I32 and the pipe I25 into the reservoir 20. Fluid entering the valve chamber II2 cannot pass out through the port I20 since thevalve I40 is closed. The Valve 29 remains in a central position until the valve pistons I64 and I65 move downwardly under the influence of the spring I6I as controlled by the opening of the adjustable needle valve I8I, thus holding the shifting of the reversing. valve to a predetermined time interval before fluid under pressure may pass from the pipe I26 into the pipe I21 and return to the reservoir 20. As soon as the valve I60 opens, the released compression of the spring I05 serves to throw the valve pistons slightly beyond the central position and the fluid under pressure within the valve chamber II2, due to the differential piston areas of the pistons 33 and 34, serves to complete the reversal of the valve so as to change the direction of flow of fluid within the system. The fluid under pressure from the pipe 24 then flows into the valve chamber 38 and through pipe 44 to the right-hand cylinder chamber to cause the table I0 to move in a direction toward the right (Fig. 1).

Table I0 continues to move towardthe right until the dog I44 engages the arm I43 of the bell crank I 40 which serves to cause a downward movement of the valve stem I 36 to open the valve and admit fluid under pressure from the pipe I45, through the valve chamber I46 and the pipe I 41, into a cylinder chamber I33 to cause an upward movement of the valve pistons I34 and I35 to close the port at the end of the pipe I 24 and prevent passage of fluid under pressure from the pipe I24 into the pipe I25. At the same time, a projection I9I of the dog 90 engages the pin 89 of the reverse lever 93 and starts it moving in a clockwise direction to throw the reverse valve into a central or neutral position, and completion of the reversal of the valve 29 is accomplished in a manner similar to that above described at the other end of the table stroke.

By manipulation of the adjustable needle valves I5I and I8I, the dwell at each end of the table movement may be adjusted as desired, that is, so that an equal dwell of the desired extent may be obtained at. both ends of the table stroke or with no dwell at one end and a predetermined dwell at the other or a short dwell at one end and a comparatively long dwell at the other, depending upon the conditions and operation being performed by the machine. It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodimerits may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a grinding machine, a longitudinally reci'procable table, means including a fluid pressure piston and cylinder to reciprocate said table, means including a control valve to controlthe admission of fluid to said cylinder, a lever operatively connected to move said valve, adjustable dogs on said table to move said lever and shift the valve to a central or neutral position at the ends of the table stroke to stop the table move-' I ment, and a hydraulically controlled mechanism which is actuated in timed relation with the table movement at the end of its reciprocatory stroke to stop and hold the reversing valve in a neutral position for a predetermined time interval before allowing the valve to shift into reverse position to start thetable moving in the opposite direction.

2. In a grinding machine, a longitudinally recontrol the shifting of said valve and start the ciprocable table, means including a fluid pressure piston and cylinder to reciprocate said table, a reversing valve to control the admission of fluid to said cylinder, adjustable dogs on said table, means including a lever actuated by said dogs to shift the valve to a central or neutral position to stop the table movement, means including a pair of adjustable hydraulically controlled mechanisms each of which includes a table actuated valve which are actuated by the table movement at each end of its reciprocatory stroke to stop and prevent the shifting of said reversing valve into the reverse position and the starting of the table movement in the reverse direction until after independently adjustable time intervals at either end of the table stroke.

3. In a grinding machine, a longitudinally reciprocable table, means including a fluid pressure piston and cylinder to reciprocate said table, a reverse valve to control the admission of fluid to said cylinder, adjustable dogs on said table,

means including a lever actuated by said dogs to shift said valve to a central or neutral position to stop the table movement, means including a hydraulically controlled fluid pressure mechanism operatively connected with the reversing valve to stop and hold said reversing valve in a central or neutral position, and a control valve actuated by the table at the end of its reciprocatory movement to actuate said hydraulically controlled fluid pressure mechanism so as to control the shifting of said valve and start the table moving in the reverse direction after a predetermined time interval.

4. In a grinding machine, a longitudinally reciprocable table, means including a fluid pressure piston, and cylinder to reciprocate said table, a reverse valve to control the admission of fluid to *said cylinder, adjustable dogs on said table, means including a lever actuated by said dogs to shift said valve toa central or neutral position to stop the table movement, a pair of independent hydraulically controlled fluid pressure mechanisms operatively connected with the reversing valve to stop and hold said valve in a central position when moved in opposite directions, and a pair of hydraulic valves which are actuated by the table at either end of its reciprocatory movement to actuate saidindependent hydraulically controlled fluid pressure mechanisms respectively so as to table moving in the reverse direction after independently adjustable time intervals at either end of the table stroke.

5. In a grinding machine, a longitudinally reciprocable table, means including a pistonand cylinder operatively connected to reciprocate said table, a control valve therefor which is arranged to admit fluid under pressure to either end of said cylinder, a pair of adjustable dogs on said table, a lever operatively connected to said valve and arranged to move said valve to a central or neutral position when acted upon by one of said dogs at the end of the reciprocatory movement of the table, a hydraulically controlled valve which is operatively connected to the control valve so as to prevent movement of said control valve beyond a central or neutral position, a valve actuated by said table dog to operate said hydraulically controlled valve, and a valve to control the rate of movement of said hydraulically controlled valve and thereby control completion of the reversal after a predetermined time interval.

6. In a grinding machine, a longitudinally reciprocable table, means including a piston and cylinder operatively connected to reciprocate said table, a reversing valve associated therewith and arranged to admit fluid under pressure to either end of said cylinder, a control lever operatively connected to move said valve, adjustable dogs on said table which are arranged to actuate said lever to shift the reversing valve to a central or neutral position at the ends of the reciprocatory movement of the table, a pair of hydraulically controlled valves to prevent shifting of the reversing valve beyond a central or neutralposition, a pair of normally closed valves operatively connected with said hydraulically controlled valves respectively which are actuated by said dogs respectively to close said hydraulically controlled valves and thereby hold'the reverse valve in a central or neutral position, and a manually adjustable throttle valve to regulate theexhaust of fluid from said hydraulically controlled valve which is arranged after a predetermined time interval to allow the reversing valve to shift into its reverse position after a predetermined period of dwell.

WALLACE H. WOOD.

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