US1473388A - Press - Google Patents

Description

Nov. 6 1923. 1,473,388

F. H. SMITH ET AL I PRESS Original Filed Feb. 24, 1920 anuawfou, dhk smith AIOLS Nowak Patented Nov. 6, 1923.

UNITED 'STATES PATENT OFFICE.

FRANK E. SMITH AND ALOTS K. NOWAK, OF CLEVELAND, OHIO.

PRESS.

Application filed February 24, 1920, Serial No. 380,814. Renewed September 80, 1921. Serial K0. 504,498.

To all whom it may concern:

Be it known that FRANK H. SMITH and ALors K. NOWAK, a subject of the King of Great Britain, and a citizen of the United States, respectively, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Presses, of which the following is a full, clear, and exact description, reference being bad to the accompany ing drawings. 1

This invention relates to presses and more particularly to mechanlcally actuated presses in which the work engaging ram may be actuated at either a slow or a rapid rate, the ram being actuated through an enclosed fluid medium by a mechanically operated piston.

The invention has for its object the production of a press for applying variable pressures which are desirable in briquetting, extruding, forging, or other pressing operation; also, to apply low or high predetermined pressures as desired or to vary at will the pressure during the operation.

A further object is to enable the material to be subjected to a predetermined pressure regardless of the compressibility of the material.

A further object of this invention is to decrease the cost and increase the capacity of such machine by having the same dlrectly driven by mechanical or electrical power or a combination of these and by the arrangement of the parts of the machine more particularly pointed out below.

An embodiment of our invention is represented by way of example in the accompanying drawing, in which:

The figure is an elevation partly in section of a press.

Referring to the drawing, an operating primary member 1 and a work engaging secondary member 2 are shown, the former comprising a piston 1 and head 1' and the latter comprislng a piston 2 terminating in a ram 2'. These members are separated by an enclosed fluid medium 3 in cylinder 4, the enclosure being made fluid-tight by suitable packing glands 5. The piston 1 being connected by rod 6 to crank shaft 7 is given a reciprocatin motion when the crank shaft is driven by t e motor 8 through the reducing gears 9. The piston 2, formin part of ram 2' is supported from the head of piston 1 by bolts 10. These bolts pull back the ram 2' and piston to return position after a downward stroke. Pistons 1 and 2 are preferably of the same crosssectional area in the cylinder 4.

The fluid medium 3 of preferably water or oil is supplied through pipe 11 which contains a check valve 12 to prevent the fluid escaping but permitting replacements for losses in the system. To the pipe 11 is also connected a fluid balance or pressure control 13. This consists of a lower casing 14 in which slides piston 15, the piston being enlarged to engage the portion 16 of the superposed structure 17, comprising an enlarged portion 18 and a smaller portion 19. The piston 15 also has a stem 20 sliding in the smaller portion 19. The lower casing or chamber 14 is supplied with a fluid under pressure, preferably air, by the compressor 22. The stem 20 is made with a small cross sectional area, so that the high pressure in cylinder 4 may be balanced with relatively low pressure in cylinder 14, as i commonly understood. While the pressure control is by way of example shown vertically arranged, it may be disposed in any other way so that forces engaging 15 and 20 may oppose each other. The total pressure, of course, e uals the pressure per square inch of the fluid times the cross sectional area of the surface of the piston in contact with the fluid.

Connected by a pipe to the chamber 14 is a cylinder 23 in which a piston 24 is-reciprocable b screw 25 engaging an internally t-hre ed bevel gear 26 which may be driven by pinion 27 on motor shaft 28. Two guide rods 29 slide in head 30 on the cylinder 23 to keep the piston and screw from rotating and to prevent sidewise lay, yet permitting vertical movement 0 the same. Exhaust port 31 is placed in the cylinder to relieve all pressure in cylinders 23 and 14 when piston 24 is moved far enough upwardly to permit the compressed fluid to escape. This construction permits the operator to vary the volume in themombined chambers 14 and 23 at will. A

By so varying the volume the pressure acting on piston 15 can be absolutely coiltrolled and this in turn will control the pressure on the fluid in line 11 and cylinder 4, thus enabling the operator to keep the pressure constant on the ram 2 while it is engaging the work. or vary the pressure to any desired amount, or relieve the pressure entirely.

To keep the pressure constant the operator moves piston 24 up at the ;same time as piston 15 descends in cylinder; keeping the volume constant. To increase or decrease the pressure while the ram 2 engages the work, piston 24 is moved at a different relative rate from that of the piston 15 so as to decrease or increase the effective volumes of cylinders 23 and 14.

By adjusting nuts 10 up or down on bolts 10, the distance between operating member 1 and the work engaging member or ram may be varied, which also varies the volume of fluid contained in cylinder 4. By so varying this relative distance the ram is adjusted with respect to the work. This adjustment -is preferably made when it is desired to have the ram engage various sizes of work with the least amount of movement when it is not engaging the work. In case it is desired, ram 2 may be left engaging the work for a long period of time while the operating piston is reciprocating. For a given machine, in case of a maximum adjustment to obtain maximum dwell, the volume of the enclosed liquid in cylinder 4 is a maximum and may, depending upon the resistance of the work, be displaced into the cylinder 19. If the resistance of the work is sufficient, the volume of liquid between the operating piston and work engaging ram may be displaced and move piston 15 down to its lowest position. thus decreasing the volume of fluid in cylinder 14 and thereby increasing its pressure to a maximum. It is also obvious that if the work yields, the amount of liquid displaced will be less and the factors mentioned above will be varied accordingly.

It will thus be swn that by the adjustment of the bolts the amount of dwell upon the work may be regulated and a relatively slow pressing operation which is made up of a series of impacts transmitted through the fluid to the work engaging ram is obtained. In case of the maximum adjustment the work engaging member 2 may be practically upon the work when the operating member 1 begins to descend, and, if the work ofl'ers relatively great resistance and does not permit the work engaging member to move downwardly as fast as the operating member, the operating member 1 will move relative to the ram, increasing the premure until it reaches its lowermost position. Of course when a pressure has been reached from the main cylinder of the ress sufiicient to overcome the pressure in the cylinder of the pressure controlling means, the piston 15 will move and permit liquid to escape from the pressure cylinder, thus permitting movement of the ram and piston'relative to each other to prevent the pressure in the cylinder from becoming dangerously high.

It will be noticed that the bolts 10 need only be strong enough to carry safely the weight of the work engaging ram, for no hydraulic pressure will be created in the cylinder until the work engaging ram meets the work, and due to the resistance offered by the work, does not move relatively as fast downwardly as the operating piston. At this moment the pressure will increase in the cylinder but also at the same instant the nuts on the bolts 10 will continue downwardly in their movement with the operating piston. so that the pressure in the cylinder will be transmitted to the work and not to the bolts.

Thus it is possible to quickly and materially vary the pressure applied on the work by ram 2 even during the process of the stroke, and this may be done regardless of the position of the upper piston 1 in its stroke.

In the ordinary operation of our press a predetermined gas pressure is supplied to the chamber 14 before any fluid is introduced into the cylinder 4, for the piston 15 must be seated against the member 16 inasmuch as any substantial unbalanced pressure on the liquid in cylinder 4, will break the supporting bolts 10. 'As pistons 1 and 2 are of the same cross sectional area they will move at the same rate of speed until ram 2' meets the work.

It is preferable that pistons 1 and 2 of the operating and work engaging members respectively be of the same cross sectional area in which case both pistons will be moving with the same speed because piston 2 is only suspended from piston 1 by bolts 10. If piston 2 is larger than piston 1 it will either tend to create a vacuum or draw more fluid into the cylinder than the system can hold on the return stroke. If piston 2 is smaller than piston 1, it will break the bolts or operate the pressure control before the work is engaged. Of course it is understood that it is possible to introduce compensating mechanism in place of bolts 10 which will give the piston 2 a different rate of speed from piston 1 and this may be proportional to the cross sectional areas of pistons 1- and 2, but

the operation of the machine, in order to vary the pressure in cylinder 4 or relieve it entirely. This is particularly applicable to forging work in which the piece to be forged should be pressed to certain see. The operator can relieve the pressure nd stop the ram' immediately when it has reached the desired point, by opening thep check valve.

It is sometimes desirable to vary the pressure for some classes of work, in which case the check valve 12 may be opened only sufficiently to partly relieve the pressure and then shut. v

From the foregoing it is obvious that the pressure control may be used simply as a safety mechanism if desired, so as to prevent the pressure in cylinder 4 becomi greater than any predetermined amount within the capacity of the machine, or the pressure control mechanism may be used to control the pressure on the work, keeping it constant, increasing or decreasing 1t, or relievin it entirely.

t will thus be seen that since the effective cross sectional. areas of the operating piston and work engaging ram are substantially equal the ram moves under certain conditions hereinbefore described at the same rate as the operating pistons and thus the ress in effect may be made to give rapid strokes and be in its operation substantially a mechanical press when operating below a certain predetermined pressure.

Having thus described one embodiment of our invention, we wish it understood that our invention is not limited to the constructions and combinations herein shown and described, but what we desire to claim is set forth in the following claims:

1. A mechanical press having a work engaging ram and a mechanically actuated piston separated by an enclosed fluid medium, means whereby the piston maybe actuated to transmit pressure intermittently to the ram, and separate means operable independently of the piston for transmitting a continuous pressure through the fluid medium to the ram.

2. A mechanical press having a work-engaging ram of indeterminate stroke and an operating piston of a fixed stroke, the ram and piston reciprocable in a cylinder and separated by a fluid medium, said ram and piston being of substantially the same cross sectional area inside said cylinder and being mechanically connected outside said cylinder, so that there may be a relative movement of the piston. and ram, whereby pressure created in the cylinder is not transmitted to said mechanical connections.

3. A mechanical press having a workengaging ram with an enlarged portion and an operating piston with a head, the ram having an indeterminate stroke and the piston a fixed stroke, the ram and piston being separated by a fluid medium and havin said head and enlarged portion mechanicaf 1y connected so that one may move relative to the other, the portions of the ram and piston contacting with the fluid medium being of substantially the same cross sectional area.

4. A mechanical press having a work-engaging ram of indeterminate stroke and an operating piston of a fixed stroke, the ram and piston being separated by a fluid medium and mechanically connected by bolts, the arrangement of the pistons and fluid being such that the bolts carry only the weight of the work engaging ram.

5. A mechanical press having a. workengaging ram of indeterminate stroke and an operating piston of a fixed stroke, the ram and piston being separated by a fluid medium and mechanically connected, the work engaging ram being suspended from the operating piston by bolts and slidableon the bolts as soon as work is engaged to release the bolts from carrying the said ram.

6. A mechanical press comprising, an operating piston and a work eng g'ng member separated by an enclosed fluid medium, pressure contro ling mechanism havin a cylinder and piston operated with flui pressure, and means for varying the pressure in the cylinder of said pressure controlling mechanism to vary the pressure on the work engagirig member during its stroke.

7. mechanical press comprising a cylinder, an operating piston and a work engaging ram separated by a fluidmedium, pressure controlling mechanism having a cylinder and piston operated with fluid pressure and means for changing the eflcctive cubical capacity of the pressure controlling cylinder.

8. A mechanical press comprising a cylinder having a piston and a work engaging ram which are separated by a fluid medlum, means for actuating the piston, means con necting said actuating means and the ram, said connecting means being constructed and arranged to permit idle movement of the ram relative to the piston, means separate from the piston for maintaining a continuous pressure upon the fluid medium, regardless of the position of the piston in the cylinder, whereby the ram may be held on the work for an indefinite period without interrupting the motion of the piston.

9. A mechanical press comprising a reciprocating operating member, a ram, and means positively connecting the operating member and ram whereby the ram may be reciprocated with the operating member or held against the work. with continuous pressure during one or more reciprocations of the operating member.

10. A mechanical press comprising a reciprocating driven member and a ram separated by a fluid medium, means for maintaining the ram a ainst the work with continuous pressure uring one or more reciprocations of the driven member.

11. A mechanical press comprising 9. cylinder, an operating piston and a work engaging) ram, said piston and ram being separated y a fluid medium, means for controlling the pressure exerted on said ram and means for adjusting said ram relative to said operatin piston to increase the dwell of said ram on t e Work.

12. A mechanical press comprising :1 cylinder, an operating piston and a work engaging ram of substantially the same cross sectional area inside the cylinder, said piston and ram being separated by a fluid medium. means for controlling the ressure exerted on the ram and means for a justing said ram relative to said operating piston to increase the dwell of said ram on the work.

13. A mechanical press comprising a cylinder, an operating piston and a work .engaging ram of substantiall the same cross sectional area inside the cylinder, said piston and ram being separated by a fluid medium, independent means for controlling the pressure exerted on the ram and means for adjusting said ram relative to said operating piston whereby the volume of fluid between them is varied, the stroke of the ram is varied and the dwell of the ram is varied.

14. A mechanical press comprising a cylinder, an operating piston and a Work engaging ram of substantially the same cross sectional area inside the cylinder, said piston and ram being separated by a fluid medium, independent variable means for controlling the pressure exerted on the ram and means for adjusting said ram relative to said operating piston whereby the volume of fluid between them is varied, the stroke of the ram is varied, and the dwell of the ram is varied.

15. In a mechanical press, a work engaging ram, rotating means driven at constant speed for reciprocating said ram, means for limiting the pressure exerted upon the work by the ram to a predetermined maximum, means for varying the period of time during which said maximum pressure is exerted, and means for increasing or decreasing the pressure at will during said period.

16. In a mechanical press, a reciprocating operating member, a work engaging ram, a hydraulic cylinder interposed between said member and ram whereby said ram is forced against the work by hydraulic pressure, and means whereby the pressure of the liquid between the operatin member and ram may be increased during 5m return stroke of the operating member.

17. A mechanical press having operating primary and work; engaging secondary avaase members, the former having fixed stroke the latter having indeterminate stroke sai members being separated by an enclosed fluid medium and having mechanical connections such that there may be relative movement of the members, and the cross sectional areas of the primary and of the secondary members contacting with Y the fluid being substantially the same.

18. A mechanical press having operating primary and work engaging secondary members, the former having fixed stroke, the latter having indeterminate stroke, said members being separated by an enclosed fluid medium and having mechanical connections such that there may be relative movement of the members, the cross sectional areasof the primary and of the secondarysmembers contacting with the fluid being su tantially the same, and pressure co rolling means connected with the enclosed fluid.

19. A press comprising a mechanically driven operating piston, a work engaging ram, a pressure controlling plunger, cylinders housing the ram, piston and plunger, means connecting the cylinders and forming with the cylinders, ram, piston and plunger a closed container for a body of liquid'ot predetermined volume, a piston carried by said plunger, acylinder for said piston adapted to contain gas under pressure to prevent movement of said plunger until a predetermined hydraulic pressure is exerted thereon, said ram and plunger being sub stantially free from hydraulic pressure except when the movement of the ram is impeded by the work, means for driving said piston, and means for connecting said ram with said driving means operable to return said ram with the operatin piston but permitting relative movement Ivetween the ram and operating piston during the working stroke.

20. A press comprising a mechanically driven operating piston, a work engaging ram having a relatively long stroke, a pressure controlling plunger, cylinders housing the ram, piston and plunger, means connecting the cylinders and forming with the cylinders, ram, piston and plunger a closed container for a body of liquid of predetermined volume, an enlarged piston carried by said plunger, a cylinder for said enlarged piston adapted to contain a body of gas under pressure to prevent movement of said plunger until a predetermined hydraulic pressure is exerted thereon, said ram and plunger being substantially free from hydraulic. pressure except when the movement of the ram is impeded by the work, and means for driving said piston.

21. In a press of the character descrbed, an operating piston and means to drive said piston, a work engaging ram, said piston and ram being separated by an enclosed our signatures in the presence of two liquid medium, means for controlling the witnesses.

pressure exerted on the Work by the ram, and additional means for varying the dwell 5 of the ram on the work while the operating piston is being reciprocated.

In testimony whereof, we hereunto affix FRANK H. SMITH, ALOIS K. NOWAK. Witnesses:

H. W. ZELLMANN, W. E. Lmsn.

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