Patent Publication Number: US-3877285-A

Title: Machine for treating workpieces at elevated pressures, especially a high-pressure press

Description:
&#39; United States Patent Trolle [451 Apr. 15, 1975 MACHINE FOR TREATING WORKPIECES AT ELEVATED PRESSURES, ESPECIALLY A HIGH-PRESSURE PRESS [30] Foreign Application Priority Data Aug. 28, 1972 Sweden 11124/72 [52] U.S. C1. 72/429; 72/453; 72/455; 100/292 [51] Int. Cl B23p 11/00 [58] Field of Search 72/455, 453, 429&#39;, 100/292 [56] References Cited UNITED STATES PATENTS 3,024,676 3/1962 Howahr 72/453 3,508,429 4/1970 Staples 72/455 3,589,278 6/1971 Brauer 72/454 3,724,311 4/1973 Streich et al 100/292 FOREIGN PATENTS OR APPLICATIONS 1,277,672 9/1968 Germany 729,451 12/1942 Germany Primary ExaminerC. W. Lanham Assistant ExaminerJames R. Duzan Attorney, Agent, or FirmFlynn &amp; Frishauf [57] ABSTRACT A machine for treating workpieces at elevated pressures, especially a press, includes a large mass flywheel without spokes, crank-shaft or central bearing means. Instead, the fly-wheel is supported at its periphery only and the inner wall of its annular body has excenter or cam curves driving the plungers of control cylinders. These communicate with a working cylinder the piston of which actuates a movable tool. The flywheel surrounds the workpiece treating mechanism.  
 10 Claims, 2 Drawing Figures MACHINE FOR TREATING WORKPIECES AT ELEVATED PRESSURES, ESPECIALLY A HIGH-PRESSURE PRESS The present invention relates to such machines, particularly forging machines and presses but also bending machines, in which a metallic workpiece is subjected to one or more impacts by a tool for the purpose of causing a plastic deformation of the workpiece. In machines of that character it is desirable to have short time periods of contact between the tool and the workpiece and also a great accuracy in the striking movement of the tool causing the impact. In some cases the tool is also called upon to operate at a high repetition rate.  
  The first one of the above two requirements, the demand for a short contact time, stems from the necessity of on the one hand protecting the tool against a considerable temperature rise and, on the other, preventing such a great heat loss from the workpiece that its capacity to be subjected to the deformation in question is reduced to an unacceptable level. In certain applications the prevailing circumstances call for a great number of strokes during a short time period.  
  When the machine operates with heavy workpieces which are to be deformed to a considerable extent a further requirement is added. In consequence of the higher values of contact area, deformation and contactpressure in combination with a short contact time, the machine must be capable of yielding a very high output power.  
  In the interest of brevity the invention will below be described with reference to a press it being, however, understood that its scope is not so limited but covers all types of machines as described hereinabove.  
  The two first-mentioned ones of the requirements above mentioned. the short contact time and the exact limitation of the stroke of the tool or the press piston, respectively, has been satisfied in excenter presses. In such presses it is also feasible instantaneously to reach a high output power, namely by relying on the fly-whee] to store dynamic energy during a great portion of the revolution in which the stroke is performed. Alternatively, energy can be stored also during two or more completely passive revolutions. However, this constructional principle solves the problems connected with the power demand only up to a certain limit since above that limit the forces appearing upon engagement of the tool rise to values which would require completely unrealistic dimensions of the crank-shaft, the clutch and the related bearings. The stresses concerned are in the first place torsional stresses in the crank-shaft and extremely high bearing pressures arising when the working impulse is derived. However, in excenter presseslike in mechanical presses generally-the agreement between the net movement of the tool and the stroke of its driving mechanism also has a negative aspect apart from the positive one, the protection against tool travel in excess of the desired stroke. This drawback resides in that the mechanical control of the tool movement not only maximizes the stroke but, equally inexorably, minimizes it. The practical consequence thereof is that if, upon the introduction of the workpiece into the press, its dimensions in the direction of working exceed the maximum tolerance, the result can be a more or less extensive breakdown of the machine in the form of a burst crankshaft, cracks in the machine frame or in the tool or damage to the bearings.  
  Alternatively, the result may be a destroyed workpiece.  
  stroke limitation and the maximum stroke can conveniently be controlled by mechanical stop means. However, the combination of high press forces and long strokes calls for big hydraulic cylinders, which fact in practice makes it impossible to instantaneously reach high power values or a high repetition rate since the corresponding large volume of the hydraulic liquid cannot be rapidly displaced into and out of the hydraulic cylinder within a time interval of the order of a fraction of a second. While such a displacement is imaginable theoretically, practical designs would result in completely unreasonable dimensions, which is especially true in respect of values, pumps and conduits. A further limitation is that the compressibility of the liquid causes problems at the extremely high pressures and large volumes here concerned. Those shortcomings of hydraulic presses when compared with mechanical excenter presses can briefly be said to involve that hydraulic presses do not offer any possibility during a short time period to derive power based on dynamic energy stored during a longer period. Instead, the power output will be limited to the purely stationary power which, keeping the piston area and stroke constant, is directly proportional to the hydraulic fluid maximum pressure limited as above explained.  
 . Summary of the Invention The object of this invention is to provide a machine for the deformation of workpieces under the influence of extremely high forces, of the order of magnitude of 10 Meganewton. More particularly, the invention aims at providing a press featuring the combined advantages of the various prior art types but not suffering from their most outstanding disadvantages. The machine according to the present invention comprises at least one stationary tool and one tool movable relatively thereto. According to the main characteristic of the invention the machine comprises a power-driven, high mass flywheel without either spokes or crank-shaft. Instead, the internal wall of the annular fly-wheel is provided with excenters, cam curves or similar control means which drive the movable tool via force-multiplying means.  
 Brief Description of the Drawings One embodiment of the invention will now be described in greater detail, reference being made to the accompanying diagrammatic drawing, in which:  
  FIG. 1 is a part-sectional vertical view of a machine according to the illustrated embodiment; and  
 FIG. 2 is a section taken along line IIII in FIG. 1.  
 Detailed Description of Illustrated Embodiments sion. The design of such a reinforcing frame is known in the art and does not form any part of the present invention. It could, however, be added that, typically, the force exerted by the biasing means maintains columns 3, 4 under compression also during the operation of the press.  
  The machine is intended by a pressing operation to deform a workpiece (not shown on the drawing) positioned between a stationary and a mobile tool. The stationary tool can be constituted either by the bottom surface of yoke 5 or, which is generally the case, by a die or the like secured thereto. The mobile tool does in this case comprises a press piston 8 cooperating with a hydraulic cylinder resting on the top of yoke 2. The wall of the hydraulic cylinder consists of a heavy ring 9 secured to a thick bottom plate 10. Between the top thereof and the bottom of piston 8 there is accordingly formed a cylinder chamber 11 for the hydraulic fluid operating the press. The cylinder chamber communicates via vertical bores 12 with four horizontally and radially extending cylinders 13, 14, 15 16. These cylinders respectively house plungers 17-20 journalled for a reciprocatory motion therein. The plungers are actuated upon by an annular fly-wheel 21 the inner wall of which has guide rails 22, 23 for four slide shoes 24-27, one for each of plungers 17-20. The guide rails are circular but excentrically located relatively to each other and in relation to the rotational axis of fly-wheel 21.  
  FIG. 2 illustrates that the four control cylinders 13-16 are arranged pairwise, each pair comprising two diametrically opposed cylinders. It is also apparent from the drawing that the cylinders are symmetrically located in relation to a vertical central plane perpendicular to the plane of the drawing in FIGS. 1 and 2. The plungers have been shown in their innermost extreme positions, i.e. the positions corresponding to a positive pressure acting on the hydraulic fluid in the press cylinder 11 for the purpose of raising piston 8. While all the four radial cylinders are active simultaneously and due to their symmetrical arrangement, which involves that two of the plungers engage the one guide rail and the remaining two the other guide rail, the result will be a self-contained system as far as the forces are concerned, i.e. actional as well as reactional forces are absorbed by the fly-wheel. The mass of the fly-wheel is typically about 50-100 tons and that very large amount of material will exert two functions.  
  The first function is the classical role of a fly-wheel, the large mass and the corresponding large inertia provide a possibility to store very high dynamic energy levels.  
  The second function is that the material of the flywheel is relied upon also to absorb the just-mentioned forces. It is accordingly a characteristic of the fly-wheel that surrounds the press and that it has neither a central wheel disc nor spokes or a crank-shaft. The absence of a crank-shaft mounted in bearings eliminates the corre sponding disadvantages above discussed.  
  The fly-wheel is surrounded by a number of supporting rollers 28 and is vertically carried by heavy rollers or wheels 29. On top of the fly-wheel there is a gear ring 30 for cooperation with drive means including pinions or tooth-wheels. Those components can be conventional and have not been shown on the drawing. Reference numeral 31 indicates clutch pieces which are ovale in a horizontal plane and located between the slide shoes 24-27 and the piston 17-20. By means of a control mechanism (not shown) these clutch means can be brought into and out of their active positions in which latter case the cylinders 13-16 are disengaged also when the fly-wheel 21 rotates. This arrangement has two advantages. The first one is that one can stop piston 8-for example in order to remove the workpiece and replace it by a fresh onewithout having to stop the fly-wheel. The second advantage is that the hydraulic system can be disconnected from the mechanical system during two or more consecutive revolutions of the fly-wheel or, stated otherwise, impulses for driving the control plungers do not have to be derived during each revolution of the fly-wheel. In this way dynamic energy can be stored during two or more consecutive revolutions, thereby increasing the le&#39;vel of the power instantaneously derived during a portion of the active revolution of the fly-wheel.  
  It has been explained above how, by virtue of the arrangement of the fly-wheel, a machine designed according to the invention is superior to excenter presses and to corresponding purely mechanical machines for the deformation of workpieces at elevated pressures. The advantages over conventional hydraulically operated machines will now be discussed. Due to the fact that the total quantity of hydraulic fluid has been drastically reduced one has substantially eliminated all of the problems stemming from the compressibility of the liquid or from the difficulty in rapidly displacing large liquid quantities through conduits, valves etc. The components of the hydraulic system have been referred to above as force-multiplying means. This forcemultiplication has two aspects: a change of the direction of the exerted force and a change of the corresponding ratio. As far as the change in direction is concerned it should now be apparent that advantages are obtained due to the absence of machine elements like crank-shafts etc. In that connection it should be observed that it would involve very considerable constructional problems to mount such a heavy fly-wheel with a horizontal instead of a vertical axis of rotation. The changed ratio normally means a reduction, i.e. the sum of the active areas of plungers 17-20 should be substantially lower than the area of press piston 8. However, it is also within the concept of the invention to dimension these components in such a way that the force exerted by the press piston is lower than the plunger forces.  
  In the practical application of the invention one may, of course, utilize several embodiments deviating from the one here described and shown for illustration purposes. The main characteristic of the fly-wheel is its annular shape, the location thereof surrounding the press, the absence of any centrally located members, such as a shaft, cranks, spokes or a disk etc., and the presence of the internal guide rails resulting in a self-contained force-transmitting system. On the other hand, the supporting or bearing means for the fly-wheel can be chosen freely. One alternative solution of the bearing problem is to utilize air cushions.  
  The number of control cylinders can vary from two and upwards. It is, however, preferred to locate the cylinders symmetrically and to have them uniformly spaced. The force transmission to plungers 17-20 can be attained by the use of any suitable means and it should especially be emphasized necessarily have to be circular and excentric but may also consist of cam curves or the like.  
  As has been explained above, clutch means 31 are preferably provided with a mechanism allowing disengagement. The release movement can take place at right angles to the rotational plane of the fly-wheel but also in that plane in which latter case the clutch means are rotated around vertical shafts. lane of the fly-wheel but also in that plane Another way of providing engage ment and disengagement is to axially displace the flywheel.  
  The press cylinder 8, 9 can be shaped in other ways than illustrated in the drawings and one can use more than one press piston. The machine can be used for pressing, forging, bending, powder-compaction and the like.  
 What is claimed is:  
 l. A machine for treating workpieces at elevated pressures, comprising:  
 movable workpiece treating means mounted to a frame;  
 a power-driven large mass annular fly-wheel surrounding said movable workpiece treating means and frame and having a radially internal wall;  
 means supporting said fly-wheel at its periphery for rotation in a substantially horizontal plane;  
 cam means on said radially internal wall of said flywheel; and  
 means operatively coupling said cam means of said fly-wheel with said movable workpiece treating means to impart operating movement thereto;  
 said supporting means supporting said fly-wheel at a low level relative to said frame so that reactional forces generated each time the workpiece treating means is operated via said cam means are transmitted to said frame at or near its center of gravity, thereby reducing tilting effects on the frame during operation of the machine.  
 2. A machine according to claim 1 wherein said movable workpiece treating means includes workpiece treating surfaces, and wherein said supporting means supports said fly-wheel at a level below the lowermost treating surfaces of said movable workpiece treating means.  
 3. A machine according to claim 1 wherein said movable workpiece treating means comprises a press.  
  4. A machine according to claim 3 wherein said press is a hydraulically operated press.  
  5. A machine according to claim 4 wherein said means operatively coupling said cam means with said movable workpiece treating means comprises at least one hydraulic cylinder having a plunger operatively coupled with said cam means, said cam means reciprocating said plunger for controlling movement of said movable work-piece treating means.  
  6. A machine as claimed in claim 5 comprising a slide shoe interconnected between said cam means and each plunger.  
  7. A machine according to claim 1 wherein said means operatively coupling said cam means with said movable workpiece treating means comprises at least one hydraulic cylinder having a plunger operatively coupled with said cam means, said cam means reciprocating said plunger for controlling movement of said movable workpiece treating means.  
  8. A machine as claimed in claim 7 comprising a slide shoe interconnected between said cam means and each plunger.  
  9. A machine according to claim 7 comprising a plurality of said hydraulic cylinders arranged in pairs, each pair comprising two diametrically opposed cylinders.  
  10. A machine according to claim 1 wherein said cam means includes at least two circular cam curves, each of which is eccentrically located in relation to the other cam curves and in relation to the rotational axis of the fly-wheel.