US1690069A - Hydraulic drive for machine tools - Google Patents

Description

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W.' FERRIS l HYDRAULIC DRIVE FOR MACHIN TOOLS Filed June 9, 1924` 2 sheets-sheet 1 C) 50 65 37 49:" P ,af W5 l l 4Z0 57 /0 2 I W W43 2/ ATToRNEY.

oct 3o, 1928 w; FERRIS HYDRAULIC-DRIYE FOR MACHINE TOOLS Fl'ed June 9, 1924 '2 Sheets-Sheet 2 I NVENTOR Wauw ERR/s BY ATTORNEY ing operation Patented Oct. 30, 1928. y

i UNITED STATES PATENT OFFICE.

` WALTER FEBRIS,VOF MILWAUKEE, WISCONSIN, ASSIGNOR T0 THE OILGEAB COM- PANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF VWISCONSIN.'

HYDRAULIC DRIVE FOR MACHINE TOOLS.

Application led June 9.1924. Serial VNo. 719,008.

This invention relates to continuously operated reciprocating machines and has for a apable of effecting a inarked increase in the number of reciprocations per hour and insurof the reciprocating part at desired speeds. Although applicable to other forms of continuously reciprocating machines this invention may be employed to particular advantage in the operation of planer tables and for .purposes of illustration Will be described as applied thereto.

In the operation of'belt driven and 'electrically driven planers considerable time is f consumed at the end of each stroke in bringing the table to rest and then returning 1t to full speed in the other direction. This loss of time is due primarily to the inertia of the rotating driving parts and in a much smaller degree to the inertia of. the reciprocating driven parts.

Two types oi hydraulic drives have hereto,- fore been proposed for use in operating planers, but neither has attained any commercial success. One type, involving a substantially constant pressure source, usually a pressuri` accumulator, has not proven successful primarily because of the inability to maintain an accurate control of the speed of the driven part. The 4other type involves a reversible flow variable delivery pump,' reversal being effected by reversing pump flow. This latter type is objectionable because of the time required ltoadjust the pump through Zero stroke position, from full delivery in one direction to full delivery in the other direction. The time actually required to effect this adjustment is commonly asmuch as three or four seconds. The time thus lost in eiiecting reversal at each end of the stroke reduces the productive capacity of the machine When operated at moderate or even relatively long strokes, and when operated at short strokes this loss becomes very pronounced. Y

One specific objet of the present invention is to reduce to a minimum the time required to -ffect the reversal. This is accomplished by the use of a hydraulic transmission drive involving a hydraulic motor to. which General aim the provision of a drive therefor measured quantities of driving li uid are delivered together with a valve mec anism for reversing thel direction of iiow to thereby effect a substantially instantaneous reversal of the motor and driven reciprocatin pa'rt. I have found that when a hydraulica 1y operated piston and cylinder are employed to reclprocate a planer table, the inertia of the reciprocating parts is practically negligible Y as compared with the force available in the form of hydraulic pressure upon the piston. Even When a rotary hydraulic motor is employed the delay in reversing isfvery slight, ecause any lag due to inertia serves merely te render more eiective the solid body of liquld within the motor cylinders by instantaneously raising the pressure therein. Thus in a planer driven by a hydraulic transmisslon mechanism, involving a valve controlled hydraulic motor whether in the formof a piston and cylinder or ofthe rotar type, the time lag due to inertia of the riving revolving parts, which is the greatest cause of sluggishness in the belt driven and electrically drivenv planers will be practically eliminated. By the vdelivery of measured quantities of driving liquid to the hydraulic motor a satisfactory control of the speed of the driven part is attained.

` Another object is to further reducev the time required to perform each complete cycle by effecting a high speed return. of the i reciprocating part after each Working stroke. This is accomplished by varyinlg the rate of delivery of driving liquid to t e hydraulicmotor at each reversal thereof. In the embodiment of the invention hereinafter described a variable displacement i to reverse due to t etime required to adjust rior machines were slow the pump through zere strokepostion. .t By 10o interposing a reversin valve between the pump and motor to e ect reversal of the motor, and by using the variable displacement function of the pump for the sole purpose of varying the operating speeds, I have rendered the machine highly productive n even short stroke work, and have in some instances doubled the productive capacity of the machine.

O ther objects and advantages will appear from the following description of an illustrative embodiment of the present invention.

In the drawings:

Figure 1 is a horizontal sectional view of a planer, equipped with a hydraulic drive and control mechanism constructed in accordance with the present invention.

Figure 2 is a side elevation of the planer of Figure 1.

Figure 3 is a sectional view of a reversing valve.

-Figure 4 is a sectional view of a portion of the control mechanism.

Fig. 5 is a view in elevation, partly in section, of the variable displacement pump shown in Figures 1 and 2.

Figs. 6 and 7 are sectional views of the valve of Figure 3 in different positions of adjustment. n

The planer shown comprises the usual work table 10, reciprocable upon and along the horizontal ways 11, supported by the base frame 12. The usual head frame 13 provides the customary support for the usual planer tool not shown. The work table carries an actuating cylinder 14 fixed to the bottom thereof and containing a piston 15 fitted for relative reciprocation therein. Hollow rods 16'and 17, extending through glands 18 and 19 in the opposite ends of the cylinder, connect the piston with cross-yokes 20 and 21 secured at the ends of the ways 11. The interior of the rods 16 and 17 communicate with the opposite ends, respectively, of the cylinder through ports 22 and 23, adjacent the' piston. Passages 24 and 25 in the cross-yokes communicate with the respective rods. It will thus be clear that fiuid pressure admitted to the left end of cylinder' 14 through one of the rods 16 will cause movement of the cylinder and table toward the left, and fluid pressure admitted to the right end of the cylinder through rod 17 will move the table to the right.

The passages 24 and 25 are connectible with an appropriate fluid pressure source through reversing valve preferably of a type which will now be described. The valve shown comprises a valve block 26, secured to the main frame of the machine, and provided With a longitudinal bore 27. A piston valve having end heads 28 and 29 connected by a reduced portion 30 is closely fitted for lengthwise reciprocation in the bore and divides the bore into three compartments 31, 32 and 33.

A fiuid supply pipe 34 communicates at all times with the intermediate compartment 32 and an exhaust pipe 35 communicates at all times with the end compartment 31. A longitudinal passage 36 through the piston valve connects the two end compartments 31 and 33. Pipes 37 and 38 leading from the passages 24 and 25, respectively, are adapted for communication with the bore 27 through ports 39 and 40 and cooperatingr annular chambers 41 and 42, respectively. The piston head 28 is arranged to pass over the chamber 41 from the position shown in Figure 3 to that shown in Figure 7, and is of such width as to completely cover and close this chamber in the intermediate position of the piston valve shown in Figure 6. The piston head 29 cooperates in a similar manner with the chamber 42 but is provided with short gashes 43 and 44 which extend inwardly from the ends toward an intermediate portion of the piston head 29, leaving the surface of the intermediate portion unbroken. These gashes cooperate with the chamber 42, when the piston valve is in the intermediate position of Figure 6 to effect communication between compartments 32 and 33.

The pipes 34 and 35 ale respectively connected with the delivery and intake sides of a variable displacement pump 45 of any well known type. The pump shown is fully described in my copending application, Serial No. 682,056, filed December 21, 1923, issued October 20, 1925, Patent No. 1,558,002. It is driven at constant speed from any appropriate source of power through the pulley 46, the displacement thereof being varied and controlled by a stem or rod 47. Movement of this stem or rod toward the left increases pump displacement so as to increase the delivery of fluid therefrom to and through the pipe 34 and movement toward the right effects a corresponding decrease in pump displacement and the rate of fluid flow.

The valve hereinabove described and the pump control rod 47 are both placed under the control of the planer table l0 so as to automatically reverse and regulate the speed of travel of the table. In the machine shown ythis mechanism comprises a transverse rock shaft 48 mounted in the base frame beneath the table. An arm 49 fixed to one end of this 'shaft is operatively connected through a control rod 50 with the piston valve above described. Fixed adjacent the other end of the rock shaft is a rocker element 51 having a pair of laterally spaced lugs 52 and 53 projecting upwardly into the path of travel of a pair of striker elements 54 and 55 carried by the table. Each striker element is supported upon a pivot pin 56 anchored in a bracket 57 fixed to the side of tne table. A compression spring 58 yieldably retains each striker element in the position shown. As the table approaches the end of its travel toward the right the element 54 strikes the lug 52 and rocks the shaft 48 in a clockwise direction (Fig. 2) and as the table approaches the end of its travel in the other direction the other element 55 strikes the lug 53 and rocks the shaft inthe opposite direction.

A vsecondrocker element 59 is carried by the rock shaft 48. This element is frictionfv` ally engaged by a springl pressed disk 6() splined to the shaft, the arrangement being such that the element 59 is vyieldably forced to rock with the shaft. This element carries an arm 61 connected with the pump control rod 447. The control rod passes through a lug 62 projecting from the frame of the machine and carries two stops 63 and 64 adjustably fixed thereto at opposite sides of the .l lug 62. Stop 63 coo erates with lug 62 to limit the movement o the control rod toward ures 1 and 2, the table is traveling toward the right on its cutting stroke. The valve and pump control rods and 47 are both in their right extreme positions so that the pum is de ivering driving Huid at a relatively s ow@ rate into and through ypipe 34. This fluid is passing from pipe34 through the intermediate compartment 32 of the valve block, and

through pipe 38 and hollow piston rod 17 into the right end of cylinder 14. Fluid from the left end of this piston is returningto the pump'through hollow rod 16, pipe 37, end compartment 31 and pipe 35. Table 10 continues to travel in this direction at a relatively slowrate until the shaft 48 is rocked `in a clockwise direction by the action -of striker element 54 against the lug 52. When this occurs the arm 49 on the rocks'haft shifts lthe rod 50 and piston valve into the extreme. left position of Figure 7. With the valve so shifted, piston head 28 closes communication between chamber 41 and compartment 31, and the intermediate portion of piston head 29 closes communication between chamber 42 and compartment 32. In this position' of the valve Huid from the pipe 34 passes through the intermediate compartment 32, and through pipe 37 and hollow piston rod 16 into the left end of cylinder 14, andthe planer table begins its return stroke toward the left. Fluid from the right end of the cylinder 14 returns to the pump through hollowrod 17, pipe 38, compartment 33, passage 36 in the i piston valve, compartment 31 and pipe 35.

Simultaneously with the shifting of the reversing valve the arm 61 on the 4rocker element 59 swings with the shaft 48 and pulls the pump control rod 47 toward the left until stop 64 thereon engages the lug 6 2'. This movementfof the rod 47 increases theiiow of iu'id Vin pipe 34s'o"that the speed of travel' ofi the planer table is greater on the return stroke than on the working stroke.

Upon approaching the end of its return stroke, element strikes lug 53, the shaft 48 and rocker elements 51 and 59 and arms 49 and 61 are rocked accordingly, the control rods 50 and 47 are returned to the positions shown, and the table begins another working stroke.

The compression springs 58 behind the striker elements 54 and 55 are ordinarily compressed by the initial engagement of tlgese elements against the lugs 52 or 53,- and by their subsequent reaction and expansionserve to force the rocker element 51 beyond an intermediate dead center. This action of the springs 58 and the momentum of the table y-may ordinarily be depended upon to complete e,the rocking action of the rocker element and shaft 48 at the end of each reciprocation of the table. v

In the machine shown, however, special provision =is made to insure complete reversal of the control valve in each instance. Mechanism for this purpose is shown in Figure 3. This mechanism includes a cam` xed to the valve control rod 50 andc provided with a pair of reversely inclined faces 66 and 67. A

plunger 68, reciprocable in a fixed bracket 69 1 secured. to the main frame of the machine, carries a cam roller 7 0 adapted to travel upon the inclined surfaces. The roller is forced 71. Each of the faces 66 and 67 merge into against the cam under the' pressure of a spring a convex surface 72 or 74, providing appropriate seats for the roller and cooperating therewith to limit the movement of the control rod 50. The arrangement is such that as the control rodfis shifted toward the left from the'limiting position shown, the pressure of the roller upon the face 66 offers resistance to this movement until the roller reaches and passes over the high point of the cam, after which lthe pressure of the roller against the face 67 assists the movement of the rod to the position in which the roller is seated against the surface 74, and the valve is completely reversed. The reverse action occurs during movement of the rodand valve in the reverse direction. Any appropriate means, such as a hand lever and eccentric 7.5-, may be providedl for temporarily withdrawing the plunger 68 and roller 70 out of engagement Awith the cam.

'51 carries a handlever 76 fixed thereto. By

manipulation of this lever the shaft 48 may be rocked to thereby shift the valve to neutrall or reverse position. It will be noted that 25' in theneutral position of the valve the fluid lllS- delivered from the pump to and through pipe'34 enters the intermediate compartment 32 of vthe valve block and passes through gashes 43, chamber 42, gashes44 and passage 36 in the piston valve to compartment 31 from which it is returned through pipe 35 to the pump without ail'ecting the planer table. It will also be noted that in this position of the piston valve the chamber Lf1 is covered by the piston head 28, so as to prevent any low in the pipe 37, and thus securely lock the planer table against accidental movement.

Although thisl invention is particularly adapted for planer drives and for purposes of illustration and explanation has been so described. its practical application to other uses, particularly in the machine tool field, is contemplated. f

I claim:

l. In a planer the combination of a reciprocating table, hydraulic means for driving said table, a variable displacement pump for operating said hydraulic means, valve mechanism interposed between said pump and hydraulic means and controlled by said table for reversing the direction of travel thereof, and means controlled by said table for varying pump displacement during said reversal.

2. In a planer the combination of a reciprocating table, hydraulic means for driving said table, a variable displacement pump for operating said hydraulic means, valve mechanism controlling communication between said pump and hydraulic means, and means controlled by said table for operating said valve mechanism and for simultaneously varying pump displacement to reverse and regulate the rate of travel of said table.

3. In a planer the combination of a reciprocating table, hydraulic means for'driving said table, a variable displacement pump for operating said hydraulic means, means for varying pump displacement, a valve mechanism controlled by said table for reversingfthe direction of travel thereof to effect a Working stroke and a return stroke, and means controlled by said table and operable upon said displacement varying means to effect a relatively slow travel of said table during a Working stroke and a faster travel thereof during a return stroke. f

4. In a machine tool the combination of a reciprocating member, a hydraulic drive therefor, a variable displacement pump for operating said drive, valve mechanism controlling communication between said pump and drive for reversing the direction of travel of said member, means for controlling pump displacement to regulate the speed of travel of said member, and means controlled by said member for actuating said valve mechanism and for simultaneously varying pump displacement.

5. In a machine of the continuously reciprocating type the combination of a reciprocating member, a hydraulic drive therefor, means for delivering a driving liquid at a predetermined rate to said drive, valve mechanism controlling communication between said means and said drive and operable to reverse the direction of travel of said member, means for varying the rate of liquid delivered to said drive, and means actuated by said member for operating said valve mechanism and for simultaneously operating said last named means.

6. In a machine of the continuously reciprocating type the combination of a reciprocating member, a hydraulic drive therefor, l a variable displacement pump for operating said drive, valve mechanism controlling communication between said pum and drive to reverse said member, means or controlling pump displacement, a member for operating said valve mechanism and said means, and means on said reciprocating member for actuating said last named member to reverse and regulate the rate of travel of said reciprocating member.

7. In a machine of the character described the combination of a reciprocating member, means including a variable displacement pump for driving said member, valve mechanism for controlling the direction of travel of said member, a control element controlled by said member for actuating said valve mechanism, and means yieldably connected with said element for varying pump displacement.

8. In a machine of the character described the combination of areciprocating member, means including a variable dis lacement pump for driving said member, va ve mechanism for controlling the direction of travel of said member, an element controlled by said member for actuating said valve mechanism, means yieldably connected with said element for varying pump displacement, and adjustable means for limiting the movement of sa1d last named means.

9. In a machine of the continuously reciprocating type the combination of a reciprocating member, a hydraulic motor for drivin said member, means for delivering measure quantities of driving liquid to said motor to effect movement of said member at a denite predetermined `rate, means for varying the rate of delivery of said driving li uid to regulate the rate of movement of sai member, a valve for reversing said motor, and means controlled by said member for operating said valve and said rate varying means.

10. In a machine of the continuously reciprocating type the combination of a reciprocating member, a piston and cylinder for driving said member, means including a pump for delivering measured quantities of driving liquid to said cylinder to effect movement of said member at a definite predetermined rate, means for varying the rate of delivery of driving liquid to said member to regulate the rate of movement thereof, a valve for reversing the direction of iow of driving liquid to said cylinder, and means controlled by said member for operating said valve and said rate varying means.

circuit,-and a head operable when in neutral position to b -pass said pump circuit, and means for shi ngsaid valve'. 4

12. .The combinationv of a driven member, a hydraulic motor for driving said member, a motor circuit, a pump, a pump circuit, and a ypiston va1ve between sald circuits for controlling the dlrection of tlow in said motor circuit, said valve comprising a casing having ports communicating with said'circmts, and a 'piston element having spaced heads cooperatmg. with said ports andv operable when in neutral position to hyp-pass said pump circuit and to b ook said motor circuit.

13. In a machine of the character described the combination of a reciprocating member,

a hydraulic motorfor driving said member, a

variable displacement limp, hydraulic conf nections between sai npump and motor through which said motor is driven lat a rate corresponding to pump displacement, said connections including a valvefor reversing .said motor, and means automatically operable at the end of each stroke of said member for operating said valve and for varying pump displacement tothereby promptly reverse and change the speed of said member.

In witness whereof, I hereunto subscribe my name this 22nd day of April, 1924.

' WALTER FERRIS.

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