US2537391A - Hydraulic ram device with intermittent high-pressure fluid supply - Google Patents

Description

Jan- 9, 1951 H. F. BAKEWELL 2,537,391

l HYDRAULIC RAM DEVICE WITH INTERMITTENT HIGH-PRESSURE FLUID SUPPLY Filed Dec. 22, 1945 2 Sheets-Sheet l gaf MgEdm/e 1N VEN TOR ATTORNEY Jan. 9, 1951 H. F.BAKEWE| L HYDRAULIC RAM DEVICE WITH INTERMITTENT HIGH-PRESSURE FLUID SUPPLY 2 Sheets-Sheet 2 Filed Deo. 22, 1945 HIB 02 OTHER ESSI/RE Sl/BQLY Patented Jan. 9, 1951 UNITED STAT'S PATENT FFICE HYDRAULIC RAM DEVICE WITH INTERMIT- TENT HIGH-PRESSURE FLUID SUPPLY 8 Claims. 1

This invention relates to hydraulic devices and pertains particularly to a hydraulic ram device adapted for pressing,l stamping, breaching, and comparable operations.

One of the particular objects of the device is to provide a main hydraulic ram structure hav-f ing hydraulic supply means operating at a relatively low pressure and effecting the major movements of lthe ram, together with an associated but separate hydraulic supply means adapted to apply relatively short duration impulses at a ma- 2, pressures inV excess of this nominal ram eiort are' requiredi According to a preferred embodiment r of the invention I` provide control means of the terially higher pressure for securing a minor y ram' movement at an increased force.

A further object of the invention is to provide a device of the character described having. a simplified form of manual controly means whereby the operator may integrate the high and low pressure hydraulic actions of the device..

A further object of the invention is to provide a hydraulic device which may be used as a press or the like which has the economy and facile maintenance advantages of. a relatively low pressure system together with important advantages of a high pressure construction.A V

According to prior practice in the art, it has been considered desirable to so design a hydraulic press construction that it is adapted to at all times exert its maximum hydraulic effort, L e., if a 20,000 lb. press is designed to operate with a 1,000 p. s. i. hydraulic supply system, 20 sq. in. will be provided on the ram member to which the pressure is to be subjected so that when the full. pressure is applied a full operation forceof 20,000' lbs. is obtained. This requires that the hydraulic supply system be adapted. to operate at the full. rated pressure at all times even though the maximum ram force of 20,000 lbs. is needed but occasionally. In many operations encountered in pressing, stamping and other methods of material handling involving the application of pressure, it is necessary to employ the maximum ram eort only occasionally, often only as a nal application of pressure to an operation whichv has been conducted for the most part at a reduced pressure, According to this invention, I utilize a relatively low pressure hydraulic system to effect the major portion of the ram movements in. a hydraulic device, in association with a h-ydraulic cylinder constructionwhich is adapted to produce a nominal ram effort under this low pressure hydraulic supplyrv and employ a separate relatively high pressure hydraulicl supply system. in association with the ram. cylinder for the purpose ot momentarily applying relatively high pressure hydraulic impulses to the ram when follower type which are in association with both the low and high pressure hydraulic operation means whereby the operator may apply the desired low pressure to the ram for operation thereof through its low pressure range and, when the occasion demands, apply the high pressure without the interruption of the low pressure. By such an arrangement, astraightening operation could be carried out on a deformed bar or the; like, for example, by applying the relatively low pressure effort on the work to build up stresses which are almost but not quite suiicient toeife'ct the desired straightening operation, and then applying one or more short duration high pressure impulses to effect small increments of movement of the pressure ram upon the Work at a materially higher pressure, after the manner of forceful hammer blows, to set the Work Other features and advantages of the' structure` will be brought out in the ensuing description of a preferred embodiment which is illusl trated in the accompanying drawings, in which:

` Fig. l. is a fragmentary vertical section of a hydraulic press construction embodying my invention;

Fig. 2 is a side elevation of the construction with portions broken away to show internal features;

Fig. 3 is a fragmentarysectional detail as taken' on line 3 3 in Fig. 2;

Fig. 4 is a fragmentary vertical section of a form of hydraulic supply means as incorporated 'in Fig, 1, taken on line 4 4 therein, and,

Fig. 5 is a schematic representation of a suit'- able electrical circuit which may' be utilized in' this invention.

Referring to the drawings, the construction may comprise a base l provided with a plurality of vertically extending guide posts 2 carrying a head 3 upon which cylinder 4 is mounted. Within this cylinder 4 I provide a ram 5 carrying' a piston 6 slidably engaging the cylinder 4 'and having at its lower end a head 'i which is adaptedl to receive a die, broach, or other instrumentality adapted to engage with a particular piece of'- Work which normally would be mounted on abolster la on the base l. Suitable packing for the ram 5 Within the lower end of the cylinder 4l maybe provided such as O rings or the like, as shown at 5w (Fig, l) similarly, O rings may be used as. piston rings as at 6a, Secured to the head 'L I provide a guide or cross-head 81 slidably mounted on the support guide posts 2, ac-

cording to more or less conventional practice.

The hydraulic supply means for the cylinder 4 may comprise a relatively low pressure valve assembly 9 and a relatively high pressure valve and pump assembly I0. As shown in Fig. 3 with more particularity, the low pressure valve assembly may be of a balanced type employing ball valves and adapted for alternative supply of hydraulic pressure to opposite sides of the piston 6, with appropriate hydraulic relief from the opposite side of the piston. A control mechanism for the ball valves is shown generally at II, comprising a valve control linkage I2 connected to a valve control rack I3 cooperating with the follow-up control structure carried by the cross-head 8, such as a gear I4 meshed with the rack I3 and carried on stub shaft I5 fixed relative to the cross-head 8, the gear I4 being provided with a reduction pinion I6 engaging with an idler gear Il mounted on stub shaft I8 which in turn engages a hand operated gear I5 mounted on shaft I9a and with a relatively constrained handle or hand-lever 20. Downward operation of the lever (counterclockwise movement as seen from Fig. 2) causes a counter-clockwise rotation of the gear I9, the pinion I6, and the gear I4, raising the rack I3, which movement is utilized to operate the low pressure valve assembly 9 in such manner as to apply pressure above the piston 6 and effect a downward movement of the ram 5.

The low pressure hydraulic valve assembly may comprise a pair of inlet valve members 2Ia and 2lb (the valve 2Ia being adapted to function-for operation of the ram 5 in the down direction, the valve 2 lb being adapted to function for operation of the ram in the up direction), anda pair of outlet valves 22a and 22h adapted respectively for establishing the necessary hydraulic relief in the down and up movements of theV ram assembly. To effect operation of the valves zia-22h, I provide valve push rods 23 and a pair of rocker arms 24 interconnected through a link 25 and coupled to the control linkage I2.

The valve arrangement shown in Fig.' 3 is adapted to open the down direction valves Zia and 22a by a downward movement of link 25, and in order to produce this downward movement by the upward movement of the rack I3, above described, I apply a direction-reversing linkage 25, of conventional form.

` The gears I4, I 6, II and I9 are preferably carried in a housing 2T mounted on the cross-head 8 and I preferably provide adjustable limitstops 28 on this housing adapted to be engaged by a stop arm 29 integral with the lever 2U, whereby the ram movement may be limited to any desired extent by suitable adustment of the stops 28 to cause the valve assembly 9 to be returned to the neutral position in Fig. 3. The operation of the follow-up mechanism and the action of the stop means will be apparent from the drawings, it being appreciated that as long as a counterclockwise rotative eifort is maintained on the lever 20, this lever will rotate in a counter-clockwise direction as the gear I4 follows down alongrv the rack I3, and the rotative eort applied to the lever 20 will maintain the rack I3 in its raised position, biasing the valve assembly to the downf stroke position. As a result of steady application of this rotative eifort, lever 2o moves both angularly and linearly in proportion to the travel of ram 5 and piston 6, the amount of these move-` ments depending on the overall ratio of gear train I4-I6-I'I-I9. If this rotative effort on the lever 29 is relieved, or impeded by the engagement of the stop arm 29 with one of the stops 28, the continued downward movement of the cross-head 8 and the housing 2l will result in downward movement of the rack I3 by movement of the cross-head, pulling the valve assembly into a neutral position at which time movement of the ram assembly will stop. The pressure applied to the piston 8 may be quantitatively controlled by the amount of pressure applied to the lever 20, which governs the extent to which the ball valves are lifted from their seats, as will be apparent,

The high pressure hydraulic supply is adapted to be applied directly to the upper end of the piston 6, and for this purpose I may provide an air cylinder 3l carrying a reciprocable piston 32 mounted on a piston rod 33 extending through the lower end of cylinder 3| and provided at its lower end with a cross-head or hammer 34 carried on guide rods 35 provided with return springs 36, the hammer 34 being adapted to forcibly engage an anvil head 3l on a high pressure pump which Ymay comprise a reciprocable pump piston 38 working in a pump cylinder 39 and provided with a return spring 38a. The pump assembly 38--33 is provided with a fluid inlet passage 4B (which may communicate with the supply of low pressure hydraulic fluid employed to operate the ram through the valve assembly 9) having a check valve 4l, and an outlet passage 42 communicating with the space 51 above the piston E within the cylinder 4, said outlet 42 being provided with a check valve 43. The pump cylinder 39 is preferably formed in the head 3 for the cylinder` 4, whereby a rigid structure is obtained and short duid lines are realized.

A suitable valve mechanism for operation of the piston 32 within cylinder 3| is provided, as

showngenerally at 44, which may comprise a piston valve having an operating rod 45a extending through a suitable opening in the crosshead or hammer 34 and provided with upper and lower stop members 45h adapted to be engaged by the hammer 34 within the limits of its operating stroke, together withvalve locator detente,

45 cooperating with a locator detent ball 41 provided with a ball spring 48. The detent construction IIS-43 serves to locate the piston valve 45 alternatively in the full position to admit air to the upper side of the piston 32, or to the bottom side of said piston, depending upon which one ofv the stop members 45h have been engaged by operation of the cross-head hammer 34. An air inlet 49 is provided, with a valve member 50 for controlling supply of operating air pressure to cylinder 3l.

The valve 50 is preferably of the solenoid control type in order to provide for electrical control of the operation of the high pressure hydraulic assembly IB, a push button 5I for closing in circuit 52 for the valve 50 being provided on the lever 2i), and inasmuch asa handle 53 may be provided in direct association with rocker arms 24 tor provide an alternative control memberpfor operation of the hydraulic assembly, I may provide a parallel-connected push button 54 on the handle 53.

In the operation of the device, assuming a desiredpiece of work is located on the bolster Ia and the desired type of tool is provided in the ram head l, the operator starts the ram in its desired downward movement by operating the lever 2B in Va counter-clockwise direction which opens the valves 2Ia and 22a applying high pressure from the inlet- 5e)H past check valve 6l) to a pas-- ais-auer sage 55 communicating to the space 5I above the pistonl Si and connecting the space 51s below! the piston 6; through line 55- to= the lower return pas.- sage 6I from the valve assembly d; The resulting application oi pressure at the space 5T will? cause downward movement oi the piston 6 and ram 5 ata rate governed by the operating capacity' oi the pressure supply system associated the assembly s. This may comprise a conventional high pressure pump mechanism not shown)` adapted to supply a pressure on the` order of 50G-1000L p; s. i. which may constitute the relativel-'y low pressure recuured. If' the area of' the piston 6 is 20 sq; in., for example, with a. loco p. s.. i'. pressure supply, a resultant pressure. effort or' 20,0001 lbsT may be applied to the Work. The operator may' apply a. greater pressure when the occasion demandsby energizing the solenoid circuit 52 for the. solenoid 5c by depressing the. push button l, whichv admit air to the cylinder 3i. above the piston 324 .ng it. downwardly and driving the associated hammer 34 against the anvil 311 of the. `33-39, forcing' hydraulic uuid through the outlet d2 pastv the. check. valve 43 into the space 5l. Pressures asf high as 10,0430 p. s.. may be produced by the compact high pressure pump assembly 38-39 (depending upon the air pressure supplied tothe cylinder 3, and the areas of the pistons 3.2 and 38)-, thus raising the pressure in space 5l commensurately and applying a resultant effort. on the ram many times that supplied by the low pressure system. A check. valve 50 is provided, as at the inlet 5?, to prevent dissipation of this high pressure back through the low pressure supply system. rIhe high pressure produced in thespace 5l will cause a. short sharp movement. of the ram 5, this' movementY rapidly dissipating the. pressure resulting from a single impulse provided by the pump piston 38, although ii the button 5i. is kept closed, a rapid succession of. increments of high. pressure application. will be maintained` The stroke of the piston 3&1 can be considered as. a constant, ier. au purposes, and the relation of. the areas oi the pistons 5 and 35 may be relied upon to establish a given. desired downward movement ofV the ram 5 for each operational stroke of the piston 38. For example, if the area of the piston 6 is a net 20 sq. in., and the displacement of the piston S8 is a net 0.2 cubic inch, each full stroke of the piston 33 may be utilized to cause a downward movement of 0.010" on the part of the ram 5.

It will be appreciated that the specic valving arrangement herein disclosed for the relatively low pressure assembly may be modied Without affecting the scope lof thisl invention, that the proposed form of relatively high pressure assembly is not required, and that other forms of follow-up control mechanisms are useful. Those skilled in the art will appreciate various modifications applicable to these elements of the invention, and I therefore do not choose to be limited to the specic details herein delineated and described, but rather to the scope oi the subjoined claims. In these claims the expressions low and high pressure Will be interpreted in the relative sense, rather than as dening pressures Within specific ranges.

I claim:

1. In a hydraulic device, the combination which comprises: a hydraulic ram provided With hydraulic fluid .supply means adapted for operation of said ram at a given maximum uid pressure; a separate hydraulic uid supply system of the reciprocating type.y adapted for' imposing an intermittent operating pressure in. excess' of said given maximum upon said ram.; control means ior said supp-ly means.; control means: for' said supply system; manually controllable operating means associatedW-ith both said control. means and mounted for movement with. said ram for separate and concurrent control oi said Supply means and said supply system; whereby said, interm-ittent operating pressure maybe caused to be: imposed upon said ram during application of said given maximum pressure.

2'.. In a hydraulic rain device, theA combination which comprises: a hydraulic: cylinder provided with a reciprccable piston member carrying a ram extending through. one end of said cylinder; lovv pressure hydraulic fluid supply means in fluid communication with said cylinder at both sides of said piston member for alternative movement of said ram in. each longitudinal direction; a high pressure. hydraulic fluid supply means,I in fluid .communication with said cylinder at one side, oi said piston member; valve control meansy for said loW pressure hyd-rsunlicI fluid supply means; and

valve control means for said high. pressure hydraulic iiuidr supply means; both said Valve con.- ,trol means including a manual control member mounted for morementwith said ram, said mannal control member being operatively associated with both or said valve` control means for separate and concurrent control of the respective hydraulic supplymeans'..

at hydraulic ram device, the combination which comprises: a hydraulic ram provided with hydraulic fluid supp-ly meansy adapted. for opera,- tiofn of said ram at a give-n maximum duid pressure; a separate hydraulic fluid` supply system including pump means: ci the reciprocating adapted for intermittently imposing operating pressures said ram in excess oi said given maximum; a huid operated piston member op.-

eratively associated with said pump means. and

adapted to eectI reciprocation thereof upon supply oi operating mud-pressure to; said piston member; manual control means for supply of operating duid-pressure to said piston mem-ber; and a manually operable. control. member said hydraulic iluid supply means, mounted 130.1' movement with said ram.

4. In a hydraulic ram device, the combination which comprises: a hydraulic cylinder provided with a reciprocable piston member carrying a ram extending through one end oi' said cylinder; low pressure hydraulic uid supply means in fluid communication with said cylinder at both sides of said piston member for alternative movement of said ram in each longitudinal direction; a high pressure hydraulic iluid supply means in uid communication with said cylinder at one side of said piston member; valve means for said 10W pressure hydraulic uid supply means; valve means for said high pressure hydraulic uid supply means; and valve control lmeans including a member mounted on the ram for movement therewith and manually movable between operating and non-operating positions to control supply of low pressure fluid to the ram, and a xed stop engageable with the manually movable member to cause the movable member to occupy a non-operating position to limit travel of the ram.

5. In a hydraulic ram device, the combination which comprises: a hydraulic cylinder provided with a reciprocable piston member carrying a ram extending through one end of said cylinder;

low Apressure hydraulic fluid supply' means in fluid communication with said cylinder at both sides of said piston member for alternative movement of said ram in each longitudinal direction; a high pressure hydraulic uid supply means in fluid communication with said cylinder at one side of said piston member; valves regulating supply of iiuid under pressure in each of said high pressure and low pressure iluid supply means; and valve control means comprising a control member rotatably mounted on the ram to move longitudinally therewith and capable of rotational movement relative to the ram during longitudinal movement o the ram, and linkage operatively connecting the control member to said valves regulating supply of fluid under pressure.`

6. A hydraulic ram device as in claim 5, in which the linkage operatively connecting the control member to the valves comprises: a rack extending parallel to the direction of ram movement and itself capable of limited longitudinal movement parallel to the direction of ram movement; a gear train operatively connecting the control member to the rack, whereby revolution of the control member moves the rack relative to the ram when the ram is stationary; and means operatively connecting the rack to the valves regulating low pressure uid supply in order to operate the valves as a result of movement of the rack.

7. In a hydraulic ram device, the combination which comprises: a hydraulic ram provided with hydraulic fluid means including supply means for operation of said ram at a given maximum fluid pressure; a second hydraulic nuid means for imposing progressively increasing operating pressures upon said ram in excess of said given maximum pressure, said second supply means comprising a cylinder, a reciprocating hydraulic pump member in said cylinder provided with a projecting piston member, a conduit providing a continuously available supply of liquid to said cylinder, and an air cylinder associated with said pump member and provided with a piston and piston rod assembly adapted to strik-e said projecting piston member upon supply of operating air pressure to said air cylinder to eiect an operating stroke of said projecting piston member;

and control means for separately controlling the supply of hydraulic fluid to the first mentioned hydraulic iluid means and the supply of operating air to the cylinder.

8. In a hydraulic ram device, the combination which comprises: a hydraulic ram provided with hydraulic fluid means including supply means for operation of said ram at a given maximum fluid pressure; a second hydraulic uid means for imposing progressively increasing operating pressures upon `said ram in excess of said given maximum pressure, said second supply means comprising a cylinder, a reciprocating hydraulic pump member in said cylinder provided with a projecting piston member, a conduit providing a continuously available supply of liquid to said cylinder, and power actuated hammer means at one end of the pump member including a hammer member adapted to strike said projecting piston member a percussive blow to eiect an operating stroke of said projecting piston member; and control means for separately controlling the supply of hydraulic fluid to the rst mentioned hydraulic fluid means and the operation of the hammer means.

HARDING F. BAKEWELL.

REFERENCES CTED The following references are of record in the file of this patent:

UNITED STATES PATENTSl Number Name Date 415,750 vane Nov. 26, 1889 552,274 Cole Dec. 31. 1895 726,425 Harmet Apr. 28, 1903 1,429,665 Wood Sept. 19, 1922 1,855,434 Vickers Apr. 26, 1932 1,883,166 Vickers Oct. 18, 1932 1,903,887 Widener Apr. 13, 1933 2,165,095 Frechette July 4, 1939 2,211,692 Ferris Aug. 13, 1940 2,267,064 Wikelund Dec. 23, 1941 2,366,417 MacMillin Jan. 2, 1945 2,373,167 Cherry Apr. 10, 1945 2,398,558 Reimuller Apr. 16, 1946 2,403,912 Doll July 16, 1946 2,404,545 Stevens July 23, 1946

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