US3150549A - Hydraulic control system for contour rool-turning lathe - Google Patents

Description

P 1964 J. N. BINNS 3,150,549

HYDRAULIC CONTROL SYSTEM FOR CONTOUR ROLL-TURNING LATHE Filed Nov. 9, 1959 2 Sheets-Sheet l O 1 In N INVENTOR.

JACK IV. BIN/VS BY ATTORNE J. N. BINNS Sept. 29, 1964 HYDRAULIC CONTROL SYSTEM F OR CONTOUR ROLL-TURNING LATHE Filed Nov. 9, 1959 2 Sheets-Sheet 2 8. v: 3 62 M m 5t 0 .mm .5: w m: 9 K 02 mm m 3. w: 5 m .Q 6 a. .NN l2 s 2 mm. m .om mm. M Mom 5 m o: w a #9 E us E m Owmm .O Qt N9 4K INVENTOR.

JACK IV. BIN/V5 ATTORNEY NON United States Patent 3,150,549 HYDRAULIG CGNTRGL SYSTEM FOR CQNTOUR HULL-TURNING LATHE Jack N. Binns, 4886 Oaklawn Drive, Cincinnati 27, Ohio Filed Nov. 9, 1959, Ser. No. 851,644 9 Claims. (63!. 8214) This invention relates to an automatic control system, and more particularly to a system for automatically controlling, correlating and synchronizing the flow of pressure media to a pair of independently operable control cylinders.

An object of the invention is to provide a hydraulic tracing system which is unique with respect to its ability and method of accurately controlling extremely small volumetric flows of hydraulic fluid without impairing its ability to control large volumes of such fluid.

Another object of the invention is to provide simple, yet highly effective means for detuning the resonant frequency of the hydraulic system away from the exciting frequency produced by oscillation of the work, tool, or certain structural members of a machine, such as, by Way of example, a roll lathe.

A further object of the invention is to provide means for accurately controlling the over-all frictional resistance of pistons in their respective cylinders whereby the frictional resistance of said pistons may be kept as low as possible and still avoid resonant vibration.

Still a further object of the invention is to provide a hydraulic tracing system having the hereinabove de scribed characteristics which may be mounted on a mov able member of the machine tool for thereby eliminating the need for flexible hoses.

These and other objects are attained by the means de* scribed herein and as disclosed in the accompanying drawings in which:

FIG. 1 is a schematic layout of a hydraulic tracing system embodying the teachings of the present invention.

FIG. 2 is a schematic layout of a modification of the system of FIG. 1.

FIG. 3 is a fragmental sectional view, greatly enlarged, of the cup-type pistons and details of the cylinder rods 25 and 51 of FIG. 2.

The present application is a continuation-in-part of my co-pending application Serial No. 648,396 filed March 25, 1957, entitled Contour Roll-Turning Lathe, now Patent No. 3,022,690 issued February 27, 1962. Reference is made to said co-pending application for a disclosure of the lathe in detail, and in particular for details of the tool-supporting cross-slide and the saddle on which the cross-slide is mounted. The present invention is directed to tracer-controlled systems which actuate and control the hydraulic motors which impart endwise movement to the saddle and transverse movement to the cross-slide.

With particular reference now to the figures, the numeral denotes generally a so-called tracer box from which a hand wheel 12 and a tracer finger 14 project. In practice the tracer finger engages and follows a templet, not illustrated, for imparting signals to the tracer box mechanism which signals in turn art translated into a flow of fluid through lines 16, 18, 20 and 22 to the control system of the present invention.

The present invention is neither concerned with nor directed to the structural or operating details of the mechanism housed within tracer box 10, hand wheel 12 or tracer finger 14. However, for convenience of detail and understanding of the mechanism housed Within box 10, reference is hereby made to U.S. Patent No. 2,332,- 533.

For ease of understanding, the present invention will be described in terms of controlling the action of a tool, not illustrated, which is suitably mounted for movement 3,150,549 Patented Sept. 29, 1964 along and also at right angles to the axis of rotation of a work piece. Longitudinal movement of the tool may be effected by movement of a saddle or carriage, not illustrated, by means of feed cylinders 6, whereas transverse movement of the tool may be effected by movement of a cross-slide, not illustrated, mounted on the saddle for transverse movement, by means of a feed cylinder 3.

With particular reference now to FIG. 1, the numerals 6 represent a pair of longitudinal feed cylinders for actuating a suitable saddle or carriage, not illustrated, which is movable longitudinally along or parallel to the axis of rotation of a lathe. The numerals 24 and 26 denote piston rods, the adjacent ends of which are connected to opposite sides 28 of the saddle or carriage denoted generally by the numeral 30; the opposite ends of each of piston rods 24 and 26 are secured to pistons 32 and 34 respectively.

The rearward chambers R of the two cylinders 6 are interconnected by means of lines 36 and 38 to a common cylinder line 40; whereas the forward chambers F of these cylinders 6 are interconnected, by means of conduits 42 and 44, to cylinder line 46. By means of this type of construction, the rod side of one of the pistons is added to the head side of the other piston, and vice versa, making the total area in either direction equal. In this manner, equal feed rates are produced in opposite directions when equal volumes of oil are pumped through lines 40 and 46 of the tracing system.

The numeral 8 denotes generally What may be referred to as the cross feed actuating cylinder which may be pro vided to move a cross slide (not shown) toward and from the Work piece. Piston rod 50' extends completely through piston 52 and through heads 54 and 56 of the cylinder 8, thereby providing equal working areas on opposite sides of the piston.

The numeral 60 denotes a hydraulic reservoir provided with a filter element 62. The hydraulic fluid drawn through filter 62 by Way of line 64 is forced through pump 66 of such design as to provide the necessary volume and pressure to the oil. Fluid under pressure from pump 66 is delivered to pressure line 68, thence to inlet port 70 of the tracer box mechanism 10. The numeral 72 denotes generally a relief valve, the purpose of which is to limit the pressure within line 68 to a predetermined value.

Solely by way of example and not by way of restriction, I have illustrated the so-called 360 hydraulic tracer mechanism, the operating parts of which are housed within tracer box 10 and from which the hand wheel 12 and the tracer finger 14 project. The deflection imparted to tracer finger 14 by a templet produces a particular flow in each of lines 16, 18, 20 and 22; wherein the flow in lines 16 and 13 will be in opposite directions but in equal volume; and wherein the direction of flow in lines 20 and 22 will be in opposite direction but in equal volume. The volumetric relationship, in the illustrated 360 tracer system, of the flow through lines 16 and 18, and the flow through lines 20 and 22 is in a sine to cosine relationship, and this relationship is utilized in guiding and controlling the velocity and direction of movement of the cutting tool through the operation of cylinders 6 and 8.

In order to achieve the desired control of the tool carrying cross-slide not shown, but connected to and actuated by cylinder 8, I have provided means in association with and operable by fluid from lines 16 and 18 for the purpose of producing a proportionate flow in lines 74 and 76, which feed opposite ends of cylinder 8, wherein the flow in these lines is exactly in the same direction as in lines 16 and 18 respectively, but in greater or lesser volume by a specific and predetermined relationship. By

the same token the direction of flow of fluid through lines 46 and 40 is controlled to produce a response in cylinders 6 which control the saddle. The net result being that as though the tracer box were directly connected to the actuating cylinders 6 and 8, except that the rate of response is selectively in greater or lesser magnitude. Thus, I impart to the system a means of suitably controlling relatively slow response rates without impairing its ability to control relatively fast rates.

The numeral 7 8 denotes a fixed displacement hydraulic motor and the numeral 80 a variable displacement pump driven by motor 78, wherein operation of the motor will determine the direction and volume of the hydraulic fluid handled by pump 80. The fixed and variable volume features could be suitably interposed on pump 80 and motor 78 without affecting the object of this invention.

A pressure regulator valve 82 in line 68 is utilized to provide an adjustable supercharge pressure in line 84. This supercharge pressure continuouly feeds the intake or suction side of pump 80 and the low pressure side of cylinder 8 regardless of the direction of movement of the piston 52. The pump St) will then build up the supercharge pressure of line 84 from its preselected pressure to whatever pressure is necessary to make the movement of the piston 52 take the volumetric output of the pump. It will be noted that the maximum pressure differential that can be developed by the output side of the pump, which is the high pressure side of the cylinder 8, is limited by the relief valve 86 and its setting, which by-passes the flow of oil around the cylinder back into the intake side of pump 80. The minimum pressure on the low pressure side of the cylinder is always constant at the supercharge pressure.

It follows then that the force required to feed the tool into the work is produced by the working area of the pistons and the pressure differential between the supercharge pressure and output pressure of their respective pumps regardless of the direction of movement of the pistons; and the rate of feed is produced by the volume of oil displaced by the pump.

For clarity of detail and understanding, the corresponding portion of the various elements appearing in FIG. 1 have been duplicated. That is, the motor 90 corresponds to the motor 78, and pump 92 corresponds with pump 30 in the foregoing description, et cetera.

Suitable means, such as, by way of example, a push rod 91, may be utilized to mechanically interconnect the displacement controlling yokes of pumps 80 and 92 for simultaneously controlling their volumetric displacement such that they are always equal during transition from one displacement to another, to maintain the sine-cosine relationship of their volumetric output; which in turn controls the operating characteristics of cylinder 8 of the crossslide and cylinders 6 of the longitudinal slide or saddle. The numerals 94 and 96 denote control cylinders which are integral components of said pumps 80 and 92 and which are operative to position the displacement control yoke of each of said pumps.

It should of course be understood that the feed rate within one particular range as determined by the displacement of pumps 80 and 92 can be varied at infinite increments by adjusting the throttle valve setting of throttle valves E and FF within the tracer box 10, see FIG. 2.

In FIG. 2 I have illustrated fully automatic means in the form of a control circuit which may be utilized for the purpose of remotely controlling and simultaneously coordinating the volumetric displacement of pumps 80 and 92' such that they are always equal during transition from one displacement to another, to maintain the sinecosine relationship of their volumetric output. The numerals 78 and 9t) denote fixed displacement hydraulic motors whose operating characteristics are determined by the direction of flow or" oil through lines 16-18 and 2 22', respectively; it being remembered that the fiow through lines 16-13 and 269-22 is a sine to cosine relationship as provided by the mechanism within tracer box it).

The numerals 1G0 and 1&2 represent control cylinders which are integral components of the variable volume pump 88*; whereas the numerals 10d and 1% represent corresponding cylinders of the variable volume pump 92.

The numeral iii denotes a flow meter the function of which is to insure that the corresponding control cylinders Mil-1G4 and 162-166 of the variable volume pumps 39 and 9 2' will be actuated at the same time and same rate so that the displacement of both of said pumps is always the same. A balancing orifice 112 is placed in line 314- which interconnects control lines 116 and 118, for the purpose of compensating for small displacement differences due to the manufacturing tolerances of the aforesaid control cylinders, flow indicator and/ or variable volume pumps.

The numeral 119 denotes generally a double four-way valve, also known commercially as a directional control valve. Said valve has two pressure ports in communication with lines 67 and 69, two pairs of cylinder ports 123-125 and 127-129, and a pair of exhaust ports in communication with lines 116 and 11%.

As illustrated, the first pair of cylinders ports 123 and 125 are connected through lines 124-126 and 130 to opposite ends of cylinders 1M and 106, respectively, of the variable volume pump 92' and the second of cylinder ports 127 and 129 are connected through lines 128 and 129-122 to opposite ends of cylinders 102 and 1%, respectively.

Any suitable means may be utilized for actuating directional control valve 119 from its normal position illustrated in FIG. 2 as provided by spring 1331, for effecting a reversal of direction of flow of fluid from pressure lines 67 and 69 to their respective sets of cylinders 100-102 and 104-106, such as, by way of example, a push button control solenoid 121 or the like.

When valve 119 is in the normal position illustrated in FIG. 2, the rate of delivery of hydraulic fluid may be in the neighborhood of cubic inch per revolution of the pumps 84) and 92, said fluid being utilized to advance the pistons in cylinders 6 and 8' for shifting the carriage in one direction and advancing the cross-slide for moving the tool into the workpiece.

However, when valve 119 has been actuated for effecting a reversal of flow to the control cylinders of pumps and 92, the rate of delivery of hydraulic fluid may be of a value such as, by way of example, 1 /2 cubic inches per revolution of said pumps.

From the foregoing, it will be understood that the primary purpose of the control circuit actuated by the double four-way valve 119 is to permit an operator to quickly and expeditiously change the rate of movement of the tool from feed to rapid traverse; that is, when cylnders and 1M are being provided with fluid, the tool will then be fed at a normal feed rate. However, actuation of the directional control valve 119 for reversing the flow of fluid to cylinders 102 and 106, respectively, will almost instantaneously result in shifting of the pistons to the other end of their stroke, thereby changing the feed rate to rapid traverse by substantially increasing the volumetric displacement of both pumps 86' and 92 by an equal amount, while maintaining equality throughout the change from normal feed rate to rapid traverse.

This same condition of maintaining the volumetric displacement of pumps 86 and 92' also occurs while shifting from rapid traverse rate to feed rate; and in passing it should be understood that the feed rate within any one particular range as determined by the displacement of pumps 89' and 92 can be varied at infinite increments by adjusting the settings of throttle valves E and FF within the tracer box 10.

The numerals 149-142 and 144-146 denote pairs of check valves in lines 120 and 124 and their respective sylinders 100 and 104 for the purpose of automatically purging trapped air from the control cylinder system. Uniformly satisfactory results have been obtained in those instances wherein only the top cylinders (100 and 104) of pumps 80 and 92 are provided with such automatic purging means.

A sequence valve 150 is provided in line 68 for regulating the control pressure applied to the variable volume pumps 80 and 92'. A pressure relief valve 156 is teed off of line 152 to control or regulate the supercharge pressure applied to the low pressure side of cylinders 6 and 8 and to the suction or intake side of pumps 80' and 92'. Pressure relief valves 158 and 160, respectively, limit the maximum pressure differential across the pistons of said feed cylinders 6' and 8.

Check valves 170, 172, 174 and 176 are provided between lines 40 and 46 for the purpose of controlling the direction of oil flow either from the supercharge line 152 or blow-off whenever the maximum pressure differential across piston 35 of cylinder 6 is exceeded.

Check valves 178, 180, 182 and 184 are associated with lines 74 and 76' for the same reason with reference to pressure differential across piston 53 of cylinder 8'.

With particular reference now to cylinders 6' and 8', it will be noted that their respective cylinder rods 25 and 51 are provided with internal passageways 200 and 202 whose opposite ends are in communication with the space between the opposite faces of pistons 35 and 53. The opposite end of passageways 200 and 202 is in open communication with the atmosphere or a sump 204. In this manner it is posible to etfectively preclude the buildup or accumulation of pressure within the space between the opposite faces of the aforesaid pistons.

When cuttting machines such as, by way of example, a contour roll lathe, is operated, oscillations are frequently set up in the work, in the cutting tool itself, or in certain portions of the lathe itself. These oscillations or vibrations are highly objectionable, and heretofore no eflective means was available for controlling or eliminating such oscillations.

According to the teachings of the present invention, it is possible to detune the resonant frequency of the hydraulic system away from the exciting frequency by regulating the setting of pressure relief valve 156, which valve is externally adjustable.

It will be noted that the supercharge pressure is the pressure on the low pressure side of each of pistons 35 and 53, whereby any increase or decrease in the low pressure side of cylinders 6' and 8' will result in a change in the basic pressure on the high pressure side of each of said cylinders; however, said change will in no way affect the overall differential existing between the high and low pressure sides of said cylinders. By way of example, if the low pressure side of cylinders 6' and 8' be 10 psi. with corresponding pressures on the high pressure side of 110 p.s.i., the pressure differential between the high and low pressure sides is 100 psi; if pressure relief valve 156 be adjusted to increase the low pressure side of the cylinders to 20 p.s.i. the high pressure side of said cylinders will instantaneously and automatically increase to 120 psi. for thereby maintaining the same overall differential between the high and low pressure sides of 100 p.s.i.

When the pressure level is altered by changing the supercharge pressure, the frictional resistance between the piston cups and the cylinder walls is correspondingly and proportionally changed.

By thus controlling the overall frictional resistance of the pistons in their respective cylinders, it is possible to effectively detune the resonant frequency of the hydraulic system away from the exciting frequency set up as a result of the operation of the machine. In the preferred embodiment of the invention, the frictional resistance of pistons 35 and 53 is maintained as low as possible but high enough to avoid resonant vibration.

Reference is made to the co-pending patent application of Francis S. Flick, Serial No. 850,727, filed November 3, 1959, now abandoned for a complete and detailed disclosure of the structural details of the piston rods 25 and 51 and the manner of venting the pistons 35 and 53 between their respective cup seals, not illustrated.

With reference now to FIG. 1, the letters A, B, C, D, and the numeral 86 denote check valves and a pressure relief valve which correspond in structure and function to check valves 178, 180, 182 and 184, and relief valve of FIG. 2. Likewise, check valves H, K, J and L of FIG. 1 correspond in structure and function with check valves 170, 172, 174 and 176 of FIG. 2. Relief valve 86 of FIG. 1 is the structural and functional equivalent of relief valves 153 and 60 of FIG. 2.

It should be understood that in those instances when the systems of FIG. 1 and/or FIG. 2 are mounted on the longitudinally movable saddle of a roll lathe, all of the fluid conduits may be substantially rigid and of copper, steel tubing, or the like, whereby to eifectively eliminate the need for flexible tubing.

In certain of the claims, operating cylinders 6 and 8 have been broadly referred to as hydraulic motors.

I claim:

1. Automatic control means for a machine having an endwise movable saddle and a tool carrying cross slide thereon, said control means comprising a first fluid motor for connection with the saddle to impart endwise movement thereto, a second fluid motor for connection with the cross slide to impart transverse movement to the latter, and a tracer controlled system operatively coupled with said first and second fluid motors for duplicating the shape of a templet in a work piece by controlling in a sine to cosine relation-ship the operating characteristics of said first and second fluid motors, and means interposed between and operatively coupled with the said tracer controlled system and each of the first and second fluid motors for increasing the range of control of said tracer means.

2. In a machine of the type which includes a saddle mounted for endwise movement and a cross slide mounted on said saddle for transverse movement relative thereto, a continuous three hundred sixty degree, templetactuated tracer, means controlled by said tracer actuating said saddle and cross slide such that the vector sum of the movements of the saddle and cross-slide is always equal to a predetermined uniform rate, and variable speed volumetric metering means interposed between and operatively coupled with the said tracer and each of the saddle and cross-slide actuating means for imparting movement to said actuating means.

3. A system adapted for automatically controlling a machine having an endwise movable saddle and a tool carrying cross-slide thereon, said control means comprising a first fluid motor means for connection with the saddle to impart endwise movement thereto, a second fluid motor means for connection with the cross slide to impart transverse movement to the latter, tracer means operatively coupled with said first and second fluid motor means for effecting duplication of the shape of a templet in a work piece by controlling in a sine to cosine relationship the operating characteristics of the said fluid motor means, and duplicate means interposed between and operatively coupled with the said tracer means and each of the fluid motor means for increasing the range of control of said tracer means.

4. The invention according to claim 3, wherein the duplicate means includes means for automatically and continuously either increasing or decreasing the operating characteristics of both of said fluid motor means in specific, predetermined, identical proportions.

5. In a control system of the class described, a first hydraulic motor, a second hydraulic motor, hydraulic tracer means adapted to follow a template to effect duplication of the template in a roll as a surface of revolution by controlling in 21 since to cosine relationship the operating characteristics of said motors, and duplicate means interposed between and operatively connected with the said hydraulic tracer means and each of said motors for increasing the range of control of said tracer means, said duplicate means comprising a variable displacement pump operatively coupled to each of said motors, and means for controlling the displacement of said variable pumps such that said displacements of said pumps are in the same rate as the displacements of their respective motors whereby displacements of the pump are always the same.

6. The system as specified in claim 5, wherein the means for controlling the displacement of said variable pumps comprises a metering device which includes a pair of du iicate metering members each of which is adapted to meter substantially identical quantities of actuating fluid for coordinating the displacement of said variable displacement pumps.

7. A hydraulic system of the character described, comprising a first hydraulic motor, a second hydraulic motor, hydraulic means for controlling in a sine to cosine relationship the operating characteristics of said motors, and duplicate hydraulic means interposed between and operatively connected with the said controlling means and each of said motors for effecting an increased range of action of said hydraulic controlling means, each said duplicate means comprising a variable displacement pump operatively connected to each of said motors, and means for controlling the displacements of said pumps such that said displacements of said pumps are in the same rate as the displacements of their respective motors whereby the displacements of the pumps are always the same.

8. A hydraulic system of the character described comprising in combination a first cylinder having a piston therein, a second cylinder having a piston therein, hydraulic means for controlling in a sine to cosine relationship the movements of the pistons in the said first and second cylinders, and duplicate hydraulic means interposed between and operatively connected with said controlling means and said cylinders on both sides of the pistons in said cylinders for effecting an increased range of action of said hydraulic controlling means, each said duplicate means comprising a variable displacement pump operatively coupled each of a hydraulic motor, and a :lluid actuated coupling means between said pumps for controlling the displacements of said pu ips such that said displacements of said pumps are in the same ratio as the displacements of their respective cylinders.

9. A cylinder including a piston having opposing pressure faces, a pair of opposed cup-type seals, and a piston rod having a passageway therethrough terminating in a port to vent a space between said opposed cup seals on the piston to a location exteriorly of said cylinder and piston rod, and means operable for controlling the frictional resistance between the periphery of the cup seals and cylinder bore by varying the pressure level of the cylinder without changing the pressure differential between the high and low pressure sides thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,996,466 Ernst Apr. 2, 1935 2,285,069 Vickers June 2, 1942 2,331,046 Robinson Oct. 5, 1943 2,332,533 Roehm Oct. 26, 1943 2,602,363 Johnson July 8, 1952 2,698,517 Witt Jan. 4, 1955 2,704,956 Johnson Mar. 29, 1955 2,791,885 Sassen May 14, 1957 2,796,793 Addison et al. June 25, 1957 2,828,610 Bruehl Apr. 1, 1958 2,910,831 Gatwood Nov. 3, 1959 2,918,905 MacLeod et a1 Dec. 29, 1959 2,929,212 Lewis et a1. Mar. 22, 1960 2,940,263 Cudnohufsky June 14, 1960

Claims (1)

1. AUTOMATIC CONTROL MEANS FOR A MACHINE HAVING AN ENDWISE MOVABLE SADDLE AND A TOOL CARRYING CROSS SLIDE THEREON, SAID CONTROL MEANS COMPRISING A FIRST FLUID MOTOR FOR CONNECTION WITH THE SADDLE TO IMPART ENDWISE MOVEMENT THERETO, A SECOND FLUID MOTOR FOR CONNECTION WITH THE CROSS SLIDE TO IMPART TRANSVERSE MOVEMENT TO THE LATTER, AND A TRACER CONTROLLED SYSTEM OPERATIVELY COUPLED WITH SAID FIRST AND SECOND FLUID MOTORS FOR DUPLICATING THE SHAPE OF A TEMPLET IN A WORK PIECE BY CONTROLLING IN A SINE TO COSINE RELATIONSHIP THE OPERATING CHARACTERISTICS OF SAID FIRST AND SECOND FLUID MOTORS, AND MEANS INTERPOSED BETWEEN AND OPERATIVELY COUPLED WITH THE SAID TRACER CONTROLLED SYSTEM AND EACH OF THE FIRST AND SECOND FLUID MOTORS FOR INCREASING THE RANGE OF CONTROL OF SAID TRACER MEANS.

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