US3640068A

US3640068A - Arbor press power source

Info

Publication number: US3640068A
Application number: US883864A
Authority: US
Inventors: Robert L Mann
Original assignee: Resinoid Engineering Corp
Current assignee: Resinoid Engineering Corp
Priority date: 1969-12-10
Filing date: 1969-12-10
Publication date: 1972-02-08
Anticipated expiration: 1989-02-08

Abstract

A power drive for an arbor press combining a rotary compressed air motor coupled with a variable volume reversible hydraulic pump supplying hydraulic fluid under pressure to a piston and cylinder moving the ram of the press whereby combinations of speed, direction and pressure at the ram may be manually achieved with stalling of the drive being inconsequential to the operativeness of the drive.

Description

o United States Patent [151 3,640,068

Mann 1 1 Feb. 8, 1972 [54] ARBOR PRESS POWER SOURCE 2,573,993 ll/ 1951 I Sedgwick ..60/52 HF X 2,931,176 4/1960 Bloch et al... ..60/52 VS [721 Park 2,984,985 5/1961 MacMillin ..60/97 P [73] Assignee: Resinoid Engineering Corporation Primary Examiner-Edgar W. Geoghegan [22] 1969 Attorney-Hofgren, Wegner, Allen, Stellman & McCord 21 A LN 883 864 l 1 pp 57 ABSTRACT 52 user ..60/52 HF 60/52 us A drive Press combining 8 [5]] Int. Cl ..F b 15/18 Pressed air motor coupled with a variable volume reversible [58] Field 0 Search 60/52 AF 52 vs 52 52 Us hydraulic pump supplying hydraulic fluid under pressure to a piston and cylinder moving the ram of the press whereby combinations of speed, direction and pressure at the ram may be [56] References cued manually achieved with stalling of the drive being incon UNITED STATES PATENTS sequential to the operativeness of the drive.

2,449,401 9/ 1948 Lindsey ..60/52 HF 3 Claims, 2 Drawing Figures 4/2 SUPPLY W 14/2 M iREGIILATOQ ARBOR PRESS POWER SOURCE BACKGROUND OF THE INVENTION 1. Field of the Invention I The present invention relates to a power unit apparatus and controls for a press.

2. Description of the Prior Art Historically, presses such as arbor presses have been operated by a lever arm connected through a rack and pinion arrangement whereby the amount of force applied to the ram was related to the pull of the operator and the mechanical advantage built into the machine. Some years ago, hydraulics were substituted for the mechanical system wherein by the manipulation of valves the ram was raised or lowered according to the adjustment of the valves.

Unfortunately, hydraulic systems have limitations, one being a positive displacement drive dependent on volume of fluid introduced. High pressures produce high forces, but control of speed with conventional hydraulic pumps and directional control valves is difficult. This can be a great disadvantage where it is desired to have the ram move a relatively long distance, for instance from a dwell position to a work contact position somewhat removed from the dwell position, in that a great deal of time is wasted in the effort. Likewise, when contact is made with the work, the force is uniformly the same and at the same speed as when the ram was moving from dwell to contact. To overcome that problem, patents on hydraulic press systems were granted, such as US. Pat. No. 2,573,993 to R. K. Sedgewick wherein the ram is moved fast under low pressure and is then switched to a booster arrangement for producing high pressure on the ram. The system requires a booster and directional control valve arrangements.

Another form of prior structure is shown in Page, US. Pat. No. 2,391,187 which provides for manually moving the ram from the dwell position to the work contact position and then applying hydraulics for exercising the high force on the workpiece. This structure had the disadvantage of requiring arrangements for releasing the ram from manual operation to hydraulic operation and the reverse which complicated the machine and produced inefficient results.

SUMMARY OF THE INVENTION The improved power unit and controls provide for air driven hydraulic pump mechanism for a press, such as an arbor press. An on-off control of an air source to an air motor provides the force for running a variable volume reversible hydraulic pump. An arrangement is provided for admitting the hydraulic pump output to the appropriate side of the piston and in appropriate amounts to move the piston and associated ram at varying speeds and pressure. Directional control valves and pressure relief valves in the hydraulic circuit are not needed and are avoided. Possibility of damage to the system is avoided in that excessive loads will only stall the air motor without damage to any parts of the system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of my air motor reversible hydraulic pump operating and control mechanism for a press; and

FIG. 2 is a schematic and diagrammatic view of the system including one operative set of controls for the hydraulic fluid from the reservoir to the hydraulic pump, to the cylinder and back.

DESCRIPTION OF THE PREFERRED EMBODIMENT One preferred embodiment of the present invention is an improvement on the operation and control of a hydraulic operated arbor press used in this case to remove cores from castings or to remove press fit parts such as bearings from their assembled sleeves.

Turning first to FIG. 1, the illustrated mechanism is designated and is shown mounted on a channel shaped base 12 which is practice can bemounted on the bed of the press 14, on the top of the press or on a separate stand accessible to the press. Mounted on the base 12 is an air motor 16 of the rotary vane type. The air motor is of standard commercially available construction such as a Leiman Bros. No. l4300. Air under pressure from an appropriate .source, such as regular shop air, is supplied to the air motor through piping l8 and exhausts through piping 20. An operating lever 22 is connected to a valve 24 which is positioned in the piping 18. for controlling the flow of air intothe air motor 16. The lever 22 and valve 24 are spring loaded to the shut off position so that release of the lever 22 will cause the valve to close, shutting off the air motor 16.

A reversible hydraulic pump 26 is mounted on the base 12 and has its input connected through an appropriate coupling 28 to the output of the air motor 16.The hydraulic pump 26 is a standard commercially available wobble plate pump, such as a Vickers reversible pump PV B 6-FRDY-l l-M-lO. A control lever 30 is mounted on a shaft 31 projecting from the hydraulic pump 26 and may beoriented in such. a way that with the lever 30.straight upthe hydraulic pump willbe in a neutral running position which in effect acts as a brake to hold a piston in a cylinder stationary since no flow of hydraulic fluid from the piston and cylinder device could occur under these circumstances. In moving vthe lever 30forward, the output of the pump will be in one direction and movement of the lever 30 beyond center in the rearward direction will reverse the direction of flow of fluid. from the pump output. The amount of movement of the lever 30 from the vertical position will determine the volume of hydraulic fluid the hydraulic pump will discharge which, of course, will determine the amount of pressure generated. The greater the volume, the lesser the pressure and vice versa due to the limited amount of driving torque delivered to the pump by the air motor 16.

The hydraulic pump, 26 has two outlets connected with the ported manifold 32. A hydraulic supply tank 34 is mounted on the base 12 and is connected throughpiping to the manifold 32.

The arbor press 14 has a hydraulic cylinder 36 mounted on the header 38 and has a piston 40 slidably mounted therein. A ram or rod 42 is connected to the piston 40 and extends through sealsin the end of the cylinder. The ram 42 is the movable operative element of the press.

Piping

44, 46 is connected into the opposite ends of the cylinder 36 to admit and withdraw fluid from opposite sides of the piston 40. The piping runs to the manifold 32 for transmitting hydraulic fluid to and from the cylinder 36.

Referring now to FIG. 2, the air supply is schematically shown connected by piping 18 to an air filter, air regulator and lubricator to the valve 24 operated by the lever 22 and into the air motor 16. The air motor of the vane type drives an output through a coupling 28 to the reversible hydraulic pump 26. The pump 26 has the two outlets 50 and 52 connected into the manifold 32 and has a drain line 54 into the tank 34. The manifold 32 has the outlet 50 of the pump connected into the passage 56 which is connected to the T-joint 58 through piping 60. The piping 44 to the upper end (cap end) of the cylinder 36 is connected to the T-joint so that the hydraulic fluid from pump 26 can pass directly into the cylinder 36 for advancing the ram 42. The third branch of theT-joint is connected to the upstream side of a one-way spring actuated check valve 62 which will permit fluidto flowto the T-joint from the tank 34, but not back to the tank therefrom except when opened by pilot pressure as will be described hereinafter. A filter 64 is mounted in the piping between the one-way valve 62 and the passage 66 through the manifold 32 leading into the tank 34. The filter can be the replacable cartridge type or any well-known hydraulic fluid filter. The passage 66 is connected by a pipe 68 into a sump in the tank 34.

When the pump 26 is discharging fluid through outlet." to the rod end of the cylinder 36, fluid is drawn into the pump from the top of the cylinder 36 through piping 44. More volume is available from the head end of the cylinder than is needed at the rod end, so that excess volume is directed to the tank 34. Outlet 52 of pump 26 is connected to passage 70 which has, in addition to the connection to outlet 52, three outlets 72,- 74, 76. Outlet 72is connected through piping 46 into the rod end of the cylinder 36. Outlet 74 is connected upstream of a one-way check valve 78 which has its downstream side connected into a sump in the tank 34. Outlet 76 from passage 70 is connected into by pilot piping 80 to the downstream side of the one-way check valve 62 so that the high pressure fluid in the pump outlet 52 opens the check valve 62 allowing the excess volume of hydraulic fluid from the cap end of the cylinder through line 44 to pass check valve 62 into the tank 34.

When the hydraulic pump 26 is set to lower the rod or ram, flow of fluid is reversed from the conditions for raising the rod or ram. Raising and lowering is by positive displacement of hydraulic fluid in the piston and cylinder device. In lowering the rod or ram, more volume of fluid must be put into the cylinder than is available from the rod end of the cylinder. The additional volume needed is obtained from the tank through check valve 78 and connected piping.

In operation, the lever 22 is operated to open air valve 24 to drive the air motor 16 which in turn rotates the appropriate parts of the wobble plate hydraulic pump 26. With the lever 30 of the pump 26 in the neutral position, no hydraulic fluid will flow from either outlet 50 or 52. Movement of the lever 30 to the forward drive position will cause outlet 52 to become an inlet and fluid both from the lower portion of the cylinder 36 through piping 46 and from the tank 34 through one-way valve 78 will be drawn into the pump 26. Outlet 50 will become the outlet through which hydraulic fluid will flow through T-joint 58 and piping 44 into the upper end of the cylinder 36. If there is no load on the rod or ram and it is desired to rapidly advance the rod or ram, the lever 30 will be moved to an extreme position which will provide large volume flow of fluid to rapidly advance the rod or ram 42 downward against practically no resistance. As the rod or ram approaches or reaches the workpiece, the lever 30 can be moved backltoward neutral which will cause lower volume flow of hydraulic fluid and less rapid advance. The operator can adjust the hydraulic pump to low volumetric output which will make available the highest pressure to the cylinder for the available power from the air motor.

To raisethe rod or ram 42, the lever 30 is pushed past the neutral position which will reverse the flow of the hydraulic fluid. That is, line 52 becomes the outlet and line 50 becomes the inlet. Hydraulic fluid will now be drawn from the top part of the cylinder 36 through piping 44 and will be forced under pressure through piping 46 into the lower part of cylinder 36. Since the volume of the lower part of cylinder 36 around the rod or ram 42 is considerable less than the volume or area of the upper part of the cylinder, far less fluid is needed to return the ram to the raised position. However, as the rod or piston 40 and ram 42 are raised, more fluid is displaced in the top part of the cylinder than is needed in the lower part of the cylinder and the flow is adjusted automatically to allow the excess to flow to the tank as described. The fluid from the upper part of the cylinder 36 passes through the pump to raise the rod or ram with the surplus fluid being discharged back to the tank through valve 62 and filter 64.

Levers

22 and 30 are spring loaded respectively to a shutofi and upstroke position, so that upon release of lever 30 the rod or ram will immediately stop advance movement and retract at least until the air supply is cut off. Release of lever 22 will then cause the air to be cut off and the rod or ram will stop. One additional feature of the pump 26 and the arrangement of the elements is that with the pump in the neutral position, no liquid volumetric changeoccurs on either side of the piston 40 so that the rod or ram will not move. This blocking effect has many advantages and in particular it has the advantage that work can be done on the rod or ram such as changing punches and the like without externally blocking the ram in a fixed position.

The

levers

22 and 30 may be extended physically or connected by linkages to controls in close proximity to the work area so that an operator can manipulate the levers with one in each hand thereby making it impossible to have a hand under the ram 42 when the press is operating. Release of either lever will stop'the rod or ram down travel.

In many manufacturing processes utilizing presses, set up time, loading time and material handling time greatly exceed the actual time for press operation. In a typical use of the arbor press drive illustrated, actual press running time was about 20 seconds in every 3 minutes on a repetitive job. Under the circumstances just enumerated, very little volume of air pressure is utilized making an air motor drive quite economical in comparison to electric motor-hydraulic pump drives with switch gear, clutches and necessary associated controls. This present air motor-hydraulic pump drive unit provides safety through stalling of the air motor without pressure relief valves yet gives the operator of the press quite wide choice of speeds and pressure with which to do the press work desired.

I claim:

1. A controllable power drive for a press having a hydraulic positive displacement piston and cylinderdevice operationally moving a press ram, comprising: a rotary vane air driven motor, means supplying air to the motor and a manual control on such means for admitting air under pressure to the air motor, a supply of hydraulic fluid, a reversible variable displacement wobble plate hydraulic pump, means coupling said air motor in driving relation to said pump, a manual control on said pump for varying volumetric output of the pump and direction of flow through the pump, said pump having two hydraulic outlets alternatively serving as inlets and means connecting each outlet to one end of the piston and cylinder device and the supply of hydraulic fluid, a one-way check valve means between each outlet of the hydraulic pump and the supply of hydraulic fluid to permit flow from the supply to the connecting means between the outlets of the hydraulic pump and the piston and cylinder device, a pilot means in said means connecting one outlet of the pump to the ram end of the piston and cylinder device, said pilot means being adapted tooperate the one-way check valve in the other outlet of the pump to permit excess hydraulic fluid to flow to the supply of hydraulic fluid from the end of the piston and cylinder device remote from the ram end, whereby selective operation of the air motor and the hydraulic pump. will vdrive the ram with all variations between low pressurehigh speed and high pressure-40w speed.

2. In a controllable power drive apparatus for a press having a hydraulic positive displacement piston and cylinder device operationally moving a press ram, in combination with a rotar-y vane air motor means, reversible wobble plate, variable displacement hydraulic pump means driven by said air motor means through a coupling means, said hydraulic pump means having a pair of hydraulic outlets alternately serving as hydraulic inlets, a manifold connected to said pair of outlets, hydraulic supply means connected with said manifold, flow means connecting said hydraulic outlets through said manifold to the upper end and to the ram end of said piston and cylinder device, one-way valve means mounted between said hydraulic supply means and each of said flow means, means for controlling air into said air motor means for driving the output of said air motor means, means for controlling the direction and volume of output of hydraulic fluid to one of said two outlets of said hydraulic pump means to determine the direction, the power and the speed of movement of said ram, and means associated with said manifold and with the one-way valve means positioned between the hydraulic supply means and said flow means to the upper end of the piston and cylinder device for opening said one-way valve means in response to excess hydraulic fluid in said ram end of the piston andcylinder device during retraction of said ram.

3. The apparatus of claim 2 wherein said means for controlling the air motor means and said means for controlling the hydraulic pump means are spring urged to shutoff positions upon release thereof.

Claims

1. A controllable power drive for a press having a hydraulic positive displacement piston and cylinder device operationally moving a press ram, comprising: a rotary vane air driven motor, means supplying air to the motor and a manual control on such means for admitting air under pressure to the air motor, a supply of hydraulic fluid, a reversible variable displacement wobble plate hydraulic pump, means coupling said air motor in driving relation to said pump, a manual control on said pump for varying volumetric output of the pump and direction of flow through the pump, said pump having two hydraulic outlets alternatively serving as inlets and means connecting each outlet to one end of the piston and cylinder device and the supply of hydraulic fluid, a one-way check valve means between each outlet of the hydraulic pump and the supply of hydraulic fluid to permit flow from the supply to the connecting means between the outlets of the hydraulic pump and the piston and cylinder device, a pilot means in said means connecting one outlet of the pump to the ram end of the piston and cylinder device, said pilot means being adapted to operate the one-way check valve in the other outlet of the pump to permit excess hydraulic fluid to flow to the supply of hydraulic fluid from the end of the piston and cylinder device remote from the ram end, whereby selective operation of the air motor and the hydraulic pump will drive the ram with all variations between low pressure- high speed and high pressurelow speed.

2. In a controllable power drive apparatus for a press having a hydraulic positive displacement piston and cylinder device operationally moving a press ram, in combination with a rotary vane air motor means, reversible wobble plate, variable displacement hydraulic pump means driven by said air motor means through a coupling means, said hydraulic pump means having a pair of hydraulic outlets alternately serving as hydraulic inlets, a manifold connected to said pair of outlets, hydraulic supply means connected with said manifold, flow means connecting said hydraulic outlets through said manifold to the upper end and to the ram end of said piston and cylinder device, one-way valve means mounted between said hydraulic supply means and each of said flow means, means for controlling air into said air motor means for driving the output of said air motor means, means for controlling the direction and volume of output of hydraulic fluid to one of said two outlets of said hydraulic pump means to determine the direction, the power and the speed of movement of said ram, and means associated with said manifold and with the one-way valve means positioned between the hydraulic supply means and said flow means to the upper end of the piston and cylinder device for opening said one-way valve means in response to excess hydraulic fluid in said ram end of the piston and cylinder device during retraction of said ram.