US3266415A

US3266415A - Air-hydraulic ram

Info

Publication number: US3266415A
Application number: US371998A
Authority: US
Inventors: Basil S Palmer
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-06-02
Filing date: 1964-06-02
Publication date: 1966-08-16
Anticipated expiration: 1983-08-16

Description

Aug. 16, 1966 B. s. PALMER i AIR-HYDRAULIC RAM 4 Sheets-Sheet l Filed June 2, 1964 B. s. PALMER AIR-HYDRAULIC RAM Filed June 2, 1964 4 Sheets-Sheet 2 )1f/1 Il (lill/fl Filed June 2, 1964 B. S. PALM ER A IR-HYDRAULI G RAM 4 sheets-sheet :s

CD@A

Aug. 16, 1966 B. s. PALMER AIR-HYDRAULIC RAM 4 Sheets-Sheet 4 Filed June 2, v1964 To D 1LT/G. 4.

United States Patent O 3,266,415 Alm-HYDRAULIC RAM Basil S. Palmer, 22 East St., Titchiieid, England Filed .lune 2, 19,64, Ser. No. 371,998 Claims. (Cl. 10U-269) This invention relates to hydraulic rams with compressed air-operated intensiers (sometimes termed airhydraulic rams).

Apart from actuators, most applications for a hydraulic ram (such as piercing, blanking, coining, staking, markin-g, rivetting, embossing, clamping and so on) only require a short working stroke although in many instances the ram mustk travel some distance before starting the working stroke in order to clear the workpiece.

With the conventional air-hydraulic ram the working stroke is limited by the disproportonal physical dimensions of the air cylinder on the intensier; eg, with an intensification of 15 to 1, -a 2 inch working stroke requires an air cylinder with a working stroke 30 inches long, together with sufficient room to displace the plunger a similar distance, the whole unit being therefore well over 6() inches long. Further the yair consumption of the conventional air-hydraulic ram is proportional to the working stroke.

A-n object of the invention is to provide an improved construction of air-hydraulic ram which requires a much shorter working stroke of the air` cylinder than that of the conventional construction and incidentally a considerable saving in air consumption. A still further object is to provide an improved hydraulic ram using a compressed air intensifier which provides a relatively long approach stroke under reduced pressure in advance of the actual power stroke and in which the pressure on the ram is automatically increased to the full working pressure when the ram contacts the work piece.

'Io these ends in accordance with the invention there is interposed between the intensifier cylinder with the plunger acting on the ram and the power cylinder and coaxial therewith at least a further auxiliary cylinder with a piston free to move on the piston of the intensiiier cylinder under air pressure and free to apply pressure through hydraulic iiuid to the ram Iand impartthe approach stroke to the ram until sealed off by movement of the plunger by .the intensifier pist-on, means being provided for restricting the speed of the initial movement of the piston of the intensifier cylinder during the approach stroke.

By way of example the invention is shown on the accompanying drawings in a simple press frame incorporating an hydraulic ram and an integral compressed airoperated intensifier. The iigures of the drawings are not all to the same scale.

FIG. 1 of the drawing is a sectional elevation with the ram at the start of the working stroke, the rearmost air connections from ythe Valve to the cylinder being in section` FIG. 2 is ya similar sectional elevation with the ram in the fully retracted position (normal or start position), the front air connection from .the valve to the cylinder being in section.

FIG. 3 is a side elevation with the control valve in section.

FIG. 4 is a plan view.

FIG. 5 is a sectional view along the line V-V in FIG. 2.

Referring to the drawings the press comprises a bot- 'tom housing 1 Iand a top housing 2 which form a power cylinder in which the ram 3 can freely slide, these housings being bolted together. with bolts (not shown).

Seals

4 and 5 and an anti-extrusion ring 6 are located between 3,256,415 Patented August 16, 1966 Mice the two housings 1 Vand 2 to form a seal between the housings and the ram 3. The anti-extrusion ring is a close tit on the large diameter portion of the ram 3 and is closely located axially between the two housings, but is free to position itself laterally.

The lower portion of the bottom housing 1 forms a bearing surface for the lower portion of the ram 3 and has an internal grove into which a seal-ing ring 7 is fitted between the housing 1 and the lower smaller diameter portion of the ram. The lower portion of the bottom housing 1 also carries a cover plate 8 retaining a wiper seal 9.

The upper portion of the top housing 2 forms a bearing surface for the upper smaller diameter portion of the ram 3 and has an opening 57 through which a plunger 11 can extend. In the opening 57 a seat 58 is provided which accommodates an annular sealing ring 10 between the top housing 2 and a plunger 11. This upper smaller diameter portion has a recess in which the plunger 11 can enter, this .recess being provided with holes 39 leading to the space between the portion of larger diameter and the top hou-sing as later explained. The upper portion of housing 2 also carries a bearing plate 112 axially locateed and serving to maintain alignment of the plunger 11 when the plunger is withdrawn from the sealing ring 10. A recess is provided forming an Iannular passage -13 between the sealing ring 10 and the bearing plate 12. The bearing plate 12 is provided with holes 41 communicating with the annular passa-ge 13 and the interior of the cylinder 14 allowing free passage of hydraulic fluid past the plunger from the cylinder 14 when the plunger is withdrawn from lthe seal provided by the ring 10.

The upper portion of the top housing 2 also forms a spigot serving to locate axially a cylinder .14 and the spigot is grooved to hold a seal 15 between the top housing 2 and the cylinder 14. The upper end of the cylinder 14 is closed by a gland plate 16 and a seal 17. T-he gland plate carries a further sealing ring 18 between itself and the plunger 11.

Located on the upper side of the gland plate is a l further cylinder 19 which is sealed to the gland plate with a seal 20. The cylinder 19 in turn is closed by a top plate 21 land a seal 22.

The cylinder 14, gland plate 16, cylinder .19 and top plate 21 are all clamped together on the top housnig by the tie-bolts 23, which can be seen most clearly in FIG. 3, and which extend vertically from corner regions 42 (see FIG. 4) of the top Ihousing 2.

A piston 24, which is attached to the plunger 11 can move freely in the cylinder 19, and is sealed to the cylinder lby a sealing ring 25. Further, a free piston 26 is sealed to the cylinder '14 by a seal 27 accommodated in a peripheral groove 59 in the free piston 26. The free piston 26 has a central opening 60 through which the plunger 11 slidingly extends. An annular groove 61 in the opening 60 accommodates a seal |28 which seals the free piston 26 relative to the plunger r11. Rubber rings indicated at 40 in FIG. 1 afford buffers for the piston 24 at either end of its stroke.

Compressed air is admitted to the press via -a coupling 29 situated on a control valve 30. The valve 30 has a spool-shaped valve member 43 urged in one axial direction by a compression spring 44 and operable in the other axial direction against the action of spring 44 by a press button 45. The valve 30 is a conventional valve having

iive ports

46, 47, 48, 49 and 50 (see FIG. 3). Port 46 is in communication with the compressed air coupling 29, port 47 is in communication with a duct 31, port 48 is in communication with a duct 32, port 49 is in communication with a duct 36 and port 50` is blocked so as to render it non-operative. In the normal oli position agee-115 air is admitted to the underside of the ram 3 through the duct 31 which is connected to the space at the underside of the ram 3 by a duct 51 (see FIG. 1), and air is also admitted to the underside of the piston 24 through the duct 32 (FIGS. 2 and 3), the duct 32 communicating with the space in the cylinder 19 below the piston 24 through a restricted passage 38 -and -a duct 52. Accordingly the ram 3 and the piston 24 are urged to their upper limit.

The hydraulic system is lled with a charge of hydraulic fluid through a filler 33 by means of a hydraulic injector gun. To achieve this the ller, which has screwed threads 56, is rst unscrewed abo-ut one turn :off the seat 34 allowing fluid to enter the system. The fluid is injected into the system until the seal 27 on the piston 26 is pushed past a bleed port 35 in the wall of the cylinder 14 and all air is expelled from the system. Both the bleed port 35 and the filler 33 are then cl-osed, and the system is sealed.

The cylinder 14 closed by the free piston 26 lforms the reservoir and contains fluid in excess of that required for operation in order to compensate for oil losses due to wipe during prolonged operation.

The operation of the ram is as follows:

When the press button 45 of the control valve 30 is depressed, the valve member 43 is moved so that

ducts

31 and 32 are opened to the atmosphere and port 49 is placed in communication with the compressed air inlet port 46. Port 49 communicates with duct 36 which itself communicates with a passage 53 provided in the gland plate 16, the passage 53 opening downwardly into the cylinder 14 above the free piston 26. A duct 37 is arranged as upward serial extension of duct 36, and communicates with a passage 54 provided in the top plate 21, the passage 54 lopening downwardly into the cylinder 19 above the piston 24.

Thus, when the press button 45 of the control valve 30 is depressed, compressed air is admitted simultaneously to the top sides of the two

pistons

24 and 26 through

ducts

36 and 37, respectively, at the same time the undersides of the ram 3 and of the piston 24 are open to atmosphere through the

ducts

31 and 32. The exhaust 'from under the piston 24 however is restricted at 38, so that there is a slight interval during which the pressure under the piston 24 collapses sulliciently for the pressure now building up on the top side of the piston to start m-oving the piston down, the interval 'being regulated by the amount of restriction at 38. During',this interval the air pressure under the ram 3 collapses immediately, allowing the air pressure on top of the free piston 26 to fonce hydraulic fluid through the holes 41 in t-he bearing plate 12 into the annular passage 13 and thence into the top housing 2 Ias shown by the arrow in FIG. 2, so forcing the ram down until it is arrested by the work piece. The piston 26 being free, the lluid pressure Iforcing the ram down during this part of the stroke will `be approximately the same as the applied air pressure.

As soon `as the air pressure under the piston 24 has collapsed suiciently to allow the piston 24 to start moving down, the plunger 11 enters the seal 10 thus sealing the uid now contained between the top of the ram 3 and the top housing 2. Further movement of the piston 24 and the plunger 11 will displace thel fluid now enclosed and cause the ram 3 to move down a further amount, this amount rbeing directly proportional to the movement o'f the piston 24 in the same ratio as that between the sectional areas of plunger 11 and the top portion of the ram 3.

The pocket in the ram 3 into which the plunger 11 can enter, has radial holes 39 through which the Huid can flow to the pocket between t-he larger rain diameter and the top housing 2, thus distributing the pressure over an area equivalent to that of the full major diameter of the ram.

Similarly if the ram is arrested, the fluid pressure on top of the ram will rise to approximately the applied air pressure times the ratio between the area of the plunger 11 and that of the piston 24, in this case 16 times.

In practice the interval between the lirst or approach part of the stroke and the second or power part of the stroke is only a fraction of a second, and the descent of the ram appears to be one continuous fast movement, although the power part of the stroke is necessarily slightly slower.

When the control valve 30 is released, on completion of a working stroke, air pressure is admitted to the underside orf the ram 3 through the duct 31, and to the underside of the piston 24 through the duct 32 as previously stated. At the same time the air pressure on top of the

pistons

24 and 26 is exhausted to atmosphere by the

ducts

36 and 37. The air piston 24 first moves up under the combined lair pressure under the piston and the Huid pressure under the plunger 11 until the latter clears the seal 10 allowing the uid on top of the ram 3 to be forced back into the cylinder 14 and the ram to be fully retracted by the air pressure under it.

The plunger of the intensifier of the illustrated machine has a 'comparatively long approach stroke, whilst still keeping the unit Within reasonable physical proportions. The total plunger stroke may be 11A" with a power stroke of approximately 1A with an intensification of 16 to 1, the total stroke of the lair cylinder Ibeing 4". By contrast, a conventional air-hydraulic press with the same intensification would require an air cylinder with a 20 inch stroke to achieve a ram stroke of 11A, and the consequent air consumption would be nearly 5 times greater.

What is claimed is:

1. A hydraulic press incorporating a double-acting ram, a power cyl-inder in which the ram is slidable in iluidtight sliding rel-ation, an auxiliary cylinder disposed above said power cylinder, an intensilier cylinder disposed above said auxiliary cylinder, an intensifier piston slidable in said intensifier cylinder in fluid-tight sliding relation, a free piston slidable in said `auxiliary cylinder in fluid-tight sliding relation, a plunger attached to said intensifier piston, an opening in said free piston through which said plunger passes, an opening in a rst end of said power cylinder through which said plunger 'ca-n enter said power cylinder, said opening being in communication with a first end of said auxiliary cylinder and witih said rst end of said power cylinder when said plunger is in its uppermost position, said communication being blocked by said plunger when said plunger is moved downwardly a given amount from its uppermost position, means for admitting a charge of operating liquid to said first end of the power cylinder and to said rst end of the auxiliary cylinder, valve means having an inlet for pressure air and a plurality of valve ports, means controlling communication between said pressure air inlet and said valve ports, a rst duct structure connecting a rst one of said valve ports to a second end of the auxiliary cylinder and to a rst end of the intensifier cylinder, a second duct structure connecting a second one of said valve ports to a second end of the intensifier cylinder, a third duct structure connecting a third one of said valve ports to a second end of the power cylinder, said communication controlling means being operative into a condition allowing admission of pressure air through said first port and rst duct structure to the second end of the auxiliary cylinder and the rst end of the intensifier cylinder, to cause the plunger to enter the power cylinder, and to permit air to exhaust from the second end of the intensier cylinder through said second duct structure and said second port and to permit air to exhaust from the second end of the power cylinder through said third duct structure and said third port, and said communication controlling means being operative into an alternative condition allowing admission of pressure air through said second port and second duct structure to the second end of the intensifier cylinder and through said third port and third duct structure to said second end of the power cylinder, and to permit air to exhaust through said rst duct structure and said irst port from said second end of the auxiliary cylinder and said firs-t end of the intensifier cylinder.

2. A hydraulic press as claimed in claim 1 in which the power cylinder, the auxiliary cylinder and the intensifier cylinder are co-axial with one another, the plunger passing co-axiallly through the auxiliary cylinder and the piston therein.

3. A hydraulic press as claimed in claim 2 in which a diaphragm formed with a bore for passage of the plunger separates the auxiliary cylinder from the power cylinder, the diaphragm being formed with at least one pas-sage leading from the adajcent end olf the auxiliary cylinder and terminating in at least one .port in the bore.

4. A hydraulic press as claimed in claim 2 in which the end of the ram adjacent to the end of the power cylinder entered by the plunge-r is formed with a deep 4recess open to one end of the ram and into which the plunger can penetrate.

5. A hydraulic press as claimed in claim 4, in which the ram presents coaxial portions including an intermediate portion fitting the maximum diameter of the power cylinder, and end portion-s of smaller diameter than said intermediate portion one of which projects from said second end of t-he power cylinder while the opposite end portion of the ram extends into and slidably operates in the first end portion of the power cylinder, the wall of said opposite end portion of the ram being provided with a passage connected into said deep recess adjacent to the intermediate portion of the ram.

References Cited by the Examiner UNITED sTATEs PATENTS 437,938 10i/1890 Naylor 60-545 512,790 1/1894 Baehman 10o-269 X 1,054,194 2/191-3 Gerdau 10o-269 1,094,092 4/1914 oyster 10o-269 1,230,492 6/1917 Krismfek en -54.5 1,888,990 11/1932 Kwam 100.269 2,403,912 7/1946 D011 60- 545 2,980,013 4/11961 swiek et a1. 10o-269 FOREIGN PATENTS 122,108 6/1948 sweden.

WALTER A. SCHEEL, Primary Examiner.

BILLY J. WILHITE, Examiner.

Claims

1. A HYDRAULIC PRESS INCORPORATING A DOUBLE-ACTING RAM, A POWER CYLINDER IN WHICH THE RAM IS SLIDABLE IN FLUIDTIGHT SLIDING RELATION, AN AXILIARY CYLINDER DISPOSED ABOVE SAID POWER CYLINDER, AN INTENSIFIER CYLINDER DISPOSED ABOVE SAID AUXILIARY CYLINDER, AN INTENSIFIER PISTON SLIDABLE IN SAID INTENSIFIER CYLINDER IN FLUID-TIGHT SLIDING RELATION, A FREE PISTON SLIDABLE IN SAID AUXILIARY CYLINDER IN FLUID-TIGHT SLIDING RELATION A PLUNGER ATTACHED TO SAID INTENSIFIER PISTON, AN OPENING IN SAID FREE PISTON THROUGH WHICH SAID PLUNGER PASSES, AN OPENING BEING IN COMMUNICATION WITH A CYLINDER THROUGH WHICH SAID PLUNGER CAN ENTER SAID POWDER CYLINDER, SAID OPENING BEING IN COMMUNICATION WITH A FIRST END OF SAID AUXILIARY CYLINDER AND WITH SAID FIRST END OF SAID POWER CYLINDER WHEN SAID PLUNGER IS IN ITS UPPERMOST POSITION, SAID COMMUNICATION BEING BLOCKED BY SAID PLUNGER WHEN SAID PLUNGER IS MOVED DOWNWARDLY A GIVEN AMOUNT FROM ITS UPPERMOST POSITION, MEANS FOR ADMITTING A CHARGE OF OPERATING LIQUID TO SAID FIRST END OF THE POWER CYLINDER AND TO SAID FIRST END OF THE AUXILIARY CYLINDER, VALVE MEANS HAVING AN INLET FOR PRESSURE AIR AND A PLURALITY OF VALVE PORTS, MEANS CONTROLLING COMMUNICATION BETWEEN SAID PRESSURE AIR INLET AND SAID VALVE PORTS, A FIRST DUCT STRUCTURE CONNECTING A FIRST ONE OF SAID VALVE PORTS TO A SECOND END<OF THE AUXILIARY CYLINDER AND TO A FIRST END OF THE INTENSIFIER CYLINDER, A SECOND DUCT STRUCTURE CONNECTING A SECOND ONE OF SAID VALVE PORTS TO A SECOND END OF THE INTENSIFIER CYLINDER, A THIRD DUCT STRUCTURE CONNECTING A THIRD ONE OF SAID VALVE PORTS TO A SECOND END OF THE POWER CYLINDER, SAID COMMUNICATION CONTROLLING MEANS BEING OPERATIVE INTO A CONDITION ALLOWING ADMISSION OF PRESSURE AIR THROUGH SAID FIRST PORT AND FIRST DUCT STRUCTURE TO THE SECOND END OF THE AUXILIARY CYLINDER AND THE FIRST END OF THE INTENSIFIER CYLINDER, TO CAUSE THE PLUNGER TO ENTER THE POWER CYLINDER, TO PERMIT AIR TO EXHAUST FROM THE SECOND END OF THE INTENSIFIER CYLINDER THROUGH SAID SECOND DUCT STRUCTURE AND SAID SECOND PORT AND TO PERMIT AIR TO EXHAUST FROM THE SECOND END OF THE POWER CYLINDER THROUGH SAID THIRD DUCT STRUCTURE AND SAID THIRD PORT, AND SAID COMMUNICATION CONTROLLING MEANS BEING OPERATIVE INTO AN ALTERNATIVE CONDITION ALLOWING ADMISSION OF PRESSURE AIR THROUGH SAID SECOND PORT AND SECOND DUCT STRUCTURE TO THE SECOND END OF THE INTENSIFIER CYLINDER AND THROUGH SAID THIRD PORT AND THIRD DUCT STRUCTURE TO SAID SECOND END OF THE POWER CYLINDER, AND TO PERMIT AIR TO EXHAUST THROUGH SAID FIRST DUCT STRUCTURE AND SAID FIRST PORT FROM SAID SECOND END OF THE AUXILIARY CYLINDER AND SAID FIRST END OF THE INTENSIFIER CYLINDER.