DE2363652A1 - ISOSTATIC PRESS - Google Patents

Description

"Isostatic Press"

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The invention relates to an isostatic press which is used in particular for compacting metal powder. The material to be pressed is in a mold with deformable walls. A relatively high pressure is applied to some or all of these outer surfaces of the mold. At least theoretically, the same pressure acts on all sides of the material to be pressed _e This is why one speaks of isostatic compression. The consequence of this is that the density of the material to be pressed is increased evenly. If the material to be pressed is a powdery substance, it is filled into the mold in the form of a "bag" at a point outside the press vessel and this bag is then immersed in a flow medium with which the chamber of the press vessel is filled This results in a precisely isostatic compression of the material to be pressed. In another type of isostatic compression, the bag filled with the powdery material is used

Patent attorneys Dipl.-Ing. Martin licht, Dipl.-Wirtsch.-Ing. Axel Hansmann, Dipl.-Phys. Sebastian Herrmann

also introduced into the chamber of the press vessel, and then the bag is closed with a stopper, furthermore the chamber of the press vessel is closed and finally open hydraulic pressure exerted on some outer surfaces of the bag, to compact the powder in the bag. The bag stays dry. This procedure is also used usually viewed as isostatic compaction, although only part of the outer surface of the bag is immediate Pressure by the fluid is subjected to the hydraulic system with which one operates the press. Another Part of the outer surfaces is not subjected to this pressure. Nevertheless, practically the same is achieved as by one theoretically perfect, isostatic compression, because forces are exerted indirectly on all non-exposed surfaces of the mold and ensure that the compression takes place essentially simultaneously and with equal force in each direction. The compression described in the dry bag offers the advantage of a higher performance of the press, because you does not need to remove the bag for filling with the powder and for discharging the compact from the pressure vessel.

In another isostatic pressing process, instead of the fluid, a relatively softer or more flowable one becomes Fabric is used, such as a rubbery fabric or elastomer that is wrapped around the fabric to be compacted (or around the shape with the deformable walls, which contains the fabric to be compacted), is arranged around and when compacting on the fabric a exerts approximately even pressure from all sides as soon as mechanical forces are exerted on the rubber-like material. With this dry bag method, the mold remains in place in the pressure vessel while it is with the one to be compressed Fabric is filled.,

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The present invention now relates primarily to improvements in the isostatic dry bag process Compaction, although the idea of the invention is equally applicable to cases in which the process is carried out by charging the mold is introduced in a position in which it is outside the pressure vessel »

Among other things, the well-known compression method occurred the task of producing an end product of uniform properties to be achieved even with a fast process flow. In particular this applies to the compression of iron-containing metal powders, for which a very high compression pressure of the order of magnitude from 2800 to 3500 atmospheres or even higher pressures are required to give the compact the required strength and density. The pressure chamber of the press is put under pressure very quickly and also quickly from this very high pressure relaxed, then it is very difficult to adjust the position of the verruabaren To master the shape in the press container exactly and to avoid undesirable effects on the material to be compacted of forces take place. So you know, for example, that if there is a very high rise in pressure in the press chamber, its walls and Closure body is subject to elastic deformation by measurable amounts, even if you are very strong and sometimes provides intricate supports to counteract such deformations or to compensate for them. To achieve that with isostatic compression at very high pressures the press used remains as intact as possible, are different Measures have been attempted; however, many of these could not meet the high performance requirements bring in line, because the pressure chamber must remain easily accessible so that you can load them at a fairly high speed and can unload »For example, closure bodies in the form of screws or bayonet catches have been tried to seal the pressure chamber of the press. Insertion

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However, such a closure body in the pressure vessel and its removal therefrom takes a lot of time, on the other hand, has one tries to use simpler closure body; but it has turned out that there are undesirable deformations of the The shape cannot be easily mastered and that it makes it difficult to quickly move the compression area within the pressure vessel to put pressure on and also to relax quickly.

The invention now offers improvements in this relatively highly developed field by providing an apparatus which can be used with a long service life for the relatively rapid manufacture of compacts. In particular, the apparatus according to the invention provides a rapid ejection of pressed parts made of a ferrous metal, which are subsequently shaped at high temperature in order to produce very precise parts of high strength, the density of which is almost 100 % of the theoretical density. It has been shown that _s successful production of such precisely measured components requires careful control of the properties of the intermediate product performing compacts, which are manufactured with the discussed below press.

According to the invention, the press has a substantially in closed isostatic aggregate, which is located inside a pressure vessel ,. It is therefore unnecessary Need to supply the pressure vessel with a high pressure fluid from an outside source Food. The self-contained isostatic unit allows the: £ use of uncommon fluids and semi-liquid materials that cannot be used in presses, which must be fed from an external source with an isostatic fluid by a pump. In the For example, some high viscosity silicones and other polymeric fluids can be used in the press of the invention.

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The self-contained isostatic unit is pressurized by a booster that is operated by a The sealing body of the pressure vessel acts through it and puts the isostatic unit under pressure within this pressure vessel, causing the closure body to slide outwardly from the pressure vessel and against a spar plate supports, but maintains a hermetic seal between the closure body and the pressure vessel.

In a particular embodiment of the invention, the pressure vessel is provided at the two ends of a through hole with closure bodies which are arranged so that the pressure vessel can be charged, pressurized, relaxed and discharged without the need for seals at either end of the hole, intended for high pressure should be solved. Furthermore, the closure bodies are designed so that they can expand in opposite directions away from the inner pressure chamber during the compression process and are supported on two spar plates arranged at a distance from one another, which are arranged and dimensioned so that they develop the very high developed in the pressure vessel Can withstand forces, between the two spaced-apart spar plates, one or more pressure vessels can be movably arranged in a holder so that they can be brought quickly one after the other between the two spar plates so that they are there after being charged with a certain amount of the compressing substance are individually put under pressure, If that happened and the pressure vessel are then released again, then each pressure vessel is again moved out of the space between the spaced-apart spar plates, so that the pressed part is discharged and each press vessel is included he can load a new amount of the material to be compacted ₀ ·

According to a further feature of the invention is the improved Provide the press with a holder, with the help of which a bag

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-like shape is hung in a chamber of a pressure vessel such that! upon pressurization and while relaxing an off ■ metered amount of the compacted material from all directions approximately equally large forces is subjected _o The holder is so disposed in the chamber that it can move freely along an axis running through the chamber by a limited distance, under the influence of the changing bridge conditions in the chamber. This displacement enables the suspended bag-like shape to follow the elastic deformations of the closure body of the press vessel without exerting undesirable stresses on the compacting substance in the mold. Thanks to this arrangement, the bag-like shape can be pressurized in a precisely controlled manner without "the reaction of the chamber to the pressure increase being transferred to the substance to be compressed With the isostatic compression process, the forces exerted on the measured amount of the substance can be better balanced and act more evenly »However, this facilitates production with very high outputs

Another feature of the invention is that provisions to be taken to a shape with deformable - η Walls within the press container exert a force with the help of a system that allows complete mastery of the work cycles allowed, with which the pressure vessel is quickly put under pressure and relaxed, these work cycles not in addition lead to any undesirable forces or impacts on the to be compacted Fabric work.

In the arrangement according to the invention, one or more pressing vessels are provided, which one after the other into the pressing position be moved, in which the compression processes at high speed = This includes relatively simple and reliable drive arrangements for bringing about the required

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movements. For example, two pressure vessels can be arranged to be pivotable about a common axis, and thereby, a complete working cycle, in which takes place the closing, compression and relaxation may be performed without the need for the relatively large and heavy pressure vessel would have to be displaced from its compacting position, or mode. Once the compression curtain has ended, the pressure vessel can be quickly turned to a point where loading and unloading takes place, while at the same time the second pressure vessel is advanced into the position in which compression takes place.

When the material to be compacted is mentioned below, which can be given a new shape or shape by means of a pressure treatment can give an increased density, it is meant by loose materials, usually in the form of powder, and this powder can be made from a wide variety of metals, synthetic plastics, ceramic materials or metal-ceramic materials exist. This term also includes substances that have been previously compressed and for increasing their density or for shaping require further pressure treatment. When speaking of a shape with deformable walls, this also refers to a bag-like shape made of an elastomer or a skin-like wall, which is to be compressed during the compression process Contains substance. Such forms can be made from a wide variety of polyurethanes and other elastomers that are characterized by flexibility, forgettability and thereby, that they return to their original size and shape after the deformation.

The term "isostatic" also includes the various Types of modified isostatic compression mentioned at the beginning.

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Now is an embodiment of the invention in explained in detail, which is shown in the drawing. In these show

Fig. 1 is an elevation of the press according to the invention and

the associated device for loading the press with the powder to be compacted and for discharging the compacted pellets,
FIG. 2 the plan belonging to FIG. 1 with the drive of two pressure vessels belonging to the press,

Fig ₀ 3 is a vertical section showing the pressure container and its contents,
4 shows a diagrammatic representation of the isostatic unit in an exploded view

its parts,
5 shows a longitudinal section through the pressure piston, which is the isostatic unit located in the pressure vessel

pressurizes
6 shows a hydraulic circuit diagram of the control for pressurizing and releasing the pressure vessel

the press according to the invention and FIG. 7 shows the circuit diagram of the drive which the two Brings pressure vessel alternately into the press and at the point for loading and unloading the Form promoted.

The particular embodiment of the invention illustrated in FIGS. 1 and 2 has two separate pressure vessels 10 and 12, which are carried by a common holder 14 on both sides of its axis of rotation 16 «, by pivoting The holder 14 alternately brings the pressure vessels around this axis into a space between two spar plates 18 and 19 the press and conveys it to a location outside the press for loading the mold and discharging the

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finished pellets. The two parallel spar plates 18 and are dimensioned relatively thick and by three columns 22 in the Distance from each other rigidly connected. These columns ^ go through holes in the spar plates and are attached to the Arranged corners of a triangle. In this way, the stresses under which the two of the Column-supported spar plates 18 and 20 are set, The in 1 and 2, where the press containers 12 and 12 are successively loaded and unloaded, is outside of the press frame. To load the press with the material to be compacted, e.g. a ferrous metal powder a feeder 24 which has a precisely measured Introduces the amount of powder to be compacted into the cavity of the mold located in each press vessel. The unloading The mold is made with the aid of an extractor 26 which grips the compact and removes it from the mold cavity in the press container pulls out. The two devices for loading the mold and for discharging the compact are shown in FIG. 2 on one common about an axis 30 pivotable holder arranged and can therefore alternately be pivoted into the position above the mold cavity of a given pressure vessel in order to achieve the To carry out loading or unloading. The two devices 24 and 26 are advanced and withdrawn by one of them Cylinder and piston existing hydraulic drive 28, each of which has one or the other device 24 and 26 opposite precisely aligned with the mold in the press container

After one of the press containers has been loaded with the material to be compacted, it becomes the joint holder for both Press container 10 and 12 swiveled quickly about the axis 16 that the loaded press container into the interior of the Press frame arrives. At the same time, the other press container is pivoted in such a way that it comes out of the press frame exits and arrives at the point of discharge. Of the

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common holder 14 of the two press containers is then locked by a wedge _? which is controlled by a hydraulic drive 27 formed by piston and cylinder. The rapid pivoting of the holder 14 with the two press containers 10 and 12 about the common axis 16 is carried out by a drive which rotates a spur gear 32 attached to the frame 14 by 180 ° and in turn is driven by a gearwheel 3 ^ which is also driven a gear 35 is coupled ₀ This meshes with a gear 36, which has a radial link slot o In this a stone 40 is displaceable which is carried by an arm 42 pivotable on the machine frame about a vertical axis 44 ₀ This arm is also shown in Figo Hydraulic motor pivoted back and forth by an angle of 90. This pivoting causes the gear wheel to rotate back and forth through 180 °. The transmission ratio of gears 36, 35, 34 and 32 is selected accordingly =

As Fig. 3 shows, each pressure vessel 10 or "12" has a pressure-resistant cylindrical body with a through axial bore 50 which forms the pressure chamber and is closed at the top and bottom by a closure body 52 or ₀ 5 ^ "This pressure chamber is hermetic during the compression process completed =

The isostatic unit, which works according to the dry bag method, consists of an inner bag 5 & j made of an elastomer and an outer bag 58 made of an elastomer. This aggregate is within the Verdicntungskammer suspended is beschicke with a certain amount of the powdered substance 60, which is to condense to form a solid compact ₀ In the illustrated embodiment, gum isostatic unit belongs further a certain amount 62 of a hydrostatic Strömungsmittelss the enclosed within a thermostatically Pressure chamber applies compaction pressure to fabric 60 when the pressure vessel is closed and pressurized.

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This is done by a device in the form of a piston 64, which is in a bore 65 of the lower closure body 5 ^ back and forth is movably guided. Through this closure body, the piston 64 exerts the pressure on the during the compression process isostatic aggregate from “This happens without the Pressure vessel would have to be fed from an external source with a pressurized pressure medium. thanks to this This arrangement eliminates the need to lay a line or high-pressure fittings through the walls of the pressure vessel to be used to the interior of the pressure vessel through the closure body 52 and 5 ^ through with the pressure fluid to dine.

If the piston 64 goes up, then the pressure vessel 10 is placed under internal pressure. On the isostatic A pressure is therefore exerted on the aggregate, with the result that the powder 60 contained in the bag-like shape 56 is removed from all of them Directions is pressed together. Since in the present embodiment the isostatic system uses a liquid to apply the isostatic pressure to the mold 56, 58, this shape 56, 58 inside is one of numerous Channels 68 arranged through the vessel 66, which carries the bag-like shape when it is not under pressure and which the Lets liquid pass through its channels 68 so that the liquid can act uniformly on the outer surfaces of the bag-like shape 56, 58. Such arrangements are inherent known.

The piston 64 is in the direction of the arrow upwards by a second piston 70 driven to the isostatic unit put under pressure. This second piston 70 is fitted in a chamber located in the bed 21 of the press and is controlled by the lower spar plate 20 carried, upward this second piston 70 is driven by the fact that its bottom surface with a

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Liquid is pressurized. The piston 70 has a slightly larger diameter than the piston 64. It therefore acts as a force amplifier ^ which multiplies the force which acts on the liquid located within the compression chamber. The union of the larger piston 70 with the smaller one Piston 64 is known for increasing piston force. The large piston 70, Fig. 3, has an upper shoulder 71 in the lower Position of the piston is located below the surface of a platform 72 which rests on the spar plate 20. Does the Approach 71 with the piston 70 upwards, then it presses from below on the smaller piston 64. This happens when the press container is to be pressurized. The downward movement of the The smaller piston 64 is limited by a stop ring 74. If the piston 64 goes down in order to relax the press chamber, then this movement can be supported by the fact that a line 76 a chamber provided in the closure body 54 238 is pressurized. This pressure then acts on you Annular surface 78 formed by a collar of the smaller piston 64 will"

In summary, it can be stated that first the mold is charged with the material 60 to be compacted, then the pressure vessel 10 is pushed into the position between the parallel spar plates 18 and 20 and then the larger piston 70 is started in the bed of the press _o The smaller piston 64 if the top is aligned with respect to the shoulder 71 of the larger piston, the pressure vessel has previously been closed by moving the closure body 52 downward. During this downward movement of the closure body 52, a plug 80 is entrained, which is pushed into the mold from above during its downward movement. The upper end of the pressure chamber of the press vessel is then closed. The up and down movement of the closure body 52 is carried out by a relatively small hydraulic thread, not shown in FIG.

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This winch is connected to the closure body 52 by a rod connected, which passes through a bore in the spar plate 18. The plug 80 is glued to the closure body 52 or otherwise attached. In the meantime, the winch driving the closure body does not need high forces during the compression process to spend because between the surface of the closure body 52 and the lower surface of the upper spar plate 18 a special Spacer plate 86 is inserted after the pressure vessel is closed. In this way it is achieved that the whole upward forces vm the pressure chamber of the pressure vessel can be exerted on the spacer plate 86 and on the very rigid spar plate 18.

Against the two closure body 52 and 5 ^ are at Compaction process exerted very high forces. The lower breech block 5 ^ is spring-loaded by a series of springs on the bed of the press Bolts 55 attached, which it the locking body 5 * 4 allow to move due to elastic deformation of the press frame downwards in the direction of the platform 72 without as a result, a hermetic seal 57 would be released between the lower closure body 5 ^ and the bore 5 ° of the pressure vessel. Upward forces act on the upper spar plate 18, while the lower spar plate 20 through the platform 72 below a downward force is applied. Now becomes the pressure vessel placed under a fairly high internal pressure (which can for example be at least 2800 atmospheres), then experience the upper and lower spar plates 18 and 20, respectively, have a noticeable elastic deflection, although they are very thick and rigid are. This slight deflection leads to a correspondingly slight displacement of the two closure bodies 52 and 5 ^ in the direction away from the pressure chamber. These shifts are so small that they do not impair the hermetic sealing of the pressure chamber in the pressure vessel.

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A further feature of the embodiment described is that a holder 90 is provided, the effect of which is to suspend the bag-like shape within the compression chamber of the press container in such a way that this shape can follow the closure body 52 when it moves in the manner described something moved up. This is very important because earlier attempts were made to fix the bag-like shape in such a way that it could not be displaced within the compression chamber. However, this easily leads to the plug 80 being pulled out of the mold during the elastic deformation of the press frame. However, this would mean that the contents of the bag-like shape would be subjected to the same stresses as occur during an extrusion process. This is avoided in the configuration described here. The shape follows the plug. 80 when this is displaced upwards together with the upper closure body 52 as a result of the elastic bending of the spar plates 18, 20. As a result, the mutual position remains between the plug and the mold maintained _o is reached this through the holder 90, which has the shape of a sleeve with an outer annular groove 92 at its upper end. This annular groove allows a limited axial displacement of the holder 90 relative to the press container 10. The holder 90 is suspended in the bore 50 with the aid of two semicircular retaining ring parts 94, each of which has a projection protruding into an annular groove 92 of the holder 90, which forms the holder 90 Bushing has a graduated inner diameter that is larger at the top and smaller at the bottom. The smaller diameter section takes the form with the deformable walls and the cup-shaped body 66, while the larger diameter section encloses a ring 9-j on which the inner bag ^ G is hung. 3 shows this holder 90 in a position in which it is shifted upwards by a small distance. However, if the pressure vessel 10 is closed by the closure body 52 after the mold has been loaded, the latter presses the holder 90 down. While

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the compression process bends the closure body 52, as described, the spar plate 18 upwards and moves up a short distance. This upward movement now makes the holder 90, this is achieved that the bag-like shape 56, 58 their predetermined relative position to Maintain stopper 80 exactly

Thanks to the socket-shaped shape of the holder 90 one can pull the closure body 52 together with the plug 80 upwards and thereby opening the press container to load the mold or remove the compact without having to to do this, the holder 90 would have to be removed from the press container. This is a significant advantage because of the ability to High pressure seal 91> associated with the holder 90 to leave in place while loading the mold or the finished compact discharges. If one had to remove the seal 91, there would be a risk of it being damaged when it slides over the top edge of the bore 50. The press container can therefore be opened and closed quickly without damaging its high pressure seals could.

The holder 90 shown in Fig. 3 has another one Effect. Namely, it reduces the diameter of the space that accommodates the isostatic unit. One can therefore use the press adapt different isostatic aggregates of larger or smaller diameter by turning the holder 90 exchanged for one that has a correspondingly differently dimensioned clear width. If you put on this additional Effect no value, then you can use the ring 96 or any use other holding part as an up and down holder of the bag-like shape and configure it so that it is at a slight upward movement of the closure body 52 and the plug 80 during compression this can follow,

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The individual parts of the isostatic unit are shown in Fig. 4t. There you can see the finished compact 100, the is rounded at its lower end and has an axial bore therethrough. He is firm enough to hold his further treatment and processing to the end product does not disintegrate. The final product can have the same shape as the compact 100 or are given a new shape and size in a subsequent shaping treatment. At the illustrated In the exemplary embodiment, the compact 100 is a body of revolution. The bottom 106 of the illustrated isostatic unit carries a mandrel 108 which forms the axial bore of the compact. You can stare at it and non-deformable bottom 106 into the socket 90 forming the holder 90 with an interference fit and this socket in turn in the bore 50 through a sleeve 110, Fig. 3 »center, which surrounds the holder 90 in its lower portion. To this Way, the isostatic unit in the bore 50 of the Pressure vessel 10 exactly centered

The sleeve 110 holds a seal ring 91 and prevents that these shifts, when the pressure vessel is pressurized ₀ The accurately centered in the bore 50 of the pressure vessel mandrel 108 may be made with the bottom 106 of one piece, for example made of steel, or can also be implemented separately and attached to the floor 106.

The bottom edge of the bag-like shape is attached to the bottom 106. This shape is defined by an inner bag 56 and an outer bag 58, both of which are formed from a Elastomer, a rubber-like material, exist. The mold forms an open-topped cavity for receiving a measured one Length of powder that is formed in the mold into the illustrated compact 100. The inner bag and the

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outer bags are nested so that they touch, with a friction sufficient to hold them together within the unit. In its bottom, each of the two bags has a hole through which the mandrel 108 protrudes and completely closes this hole, so that no powder can fall out of the bottom of the mold when compacting. The mandrel can have a groove 112 which receives the edge of the hole in the bottom of the bag 58, and tightly seals the bag in this way below. The cup-shaped body 66, the wall of which has numerous transverse bores, which allow the pressure fluid to act on the entire outer surface of the bag, is now supported on the base 106. The outside diameter of this body is significantly smaller than the clear width of the bore that accommodates the isostatic unit, so that there remains a sufficiently wide margin for the free flow of the pressure medium around the body 66. The chamber enclosed by the body 66 is dimensioned and designed in such a way that it can receive the bag in the relaxed state without deforming it in the process.

The ring 96 made of metal or some other sufficiently rigid material forms a relatively rigid holder which can support the entire weight of the isostatic unit and its contents when it is attached to it and lowered into the pressure chamber of the pressure vessel. Also, the ring 96 must absorb the load caused by the air pressure difference when the piston is moved down 64, and thereby a T _e ilvakuum can act on the mold, thereby it is stretched and pressed against the inner wall of the body 66 after the compaction ends is.

The isostatic unit illustrated in FIG. 4 represents only one embodiment which can be used in the pressure vessel of the press according to the present invention _{or the like}

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2363852

FIG _o 5 illustrates the structure of the compaction means formed by the piston 64 _s through which the liquid is set isostatic assembly within the compression chamber at a fairly high pressure 62 _o When this happens, some leakage liquid flows on the piston 64 over and must therefore be replaced running » This is done by a in Fig. Auffülleinrichtungο shown in Figure 5, the pivotal holder 14, 10 and 12 carrying the two pressure-resistant cylindrical body is _s provided with a Tanklil whose liquid content is under pressure and through the aforementioned line? 6 the pressure resistant cylindrical bodies 10 supplied -is ₀ The pressure in the tank ill is generated by the fact that the gas content of this container is set under an adjustable pressure Unit is relieved of pressure »The This depressurization causes the mold to be pulled outward to cling to the inner wall of the body 66. The line 76 leads from the tank iii to the chamber 238 and acts in this on the annular surface 78 of the piston 64 _O. Furthermore, the pressure fluid is passed from the chamber 238 through one or more bores 120 into a longitudinal bore 121 of the piston 64. This longitudinal bore thus serves to accommodate such a liquid supply. The longitudinal bore is closed at its bottom by a cover 122 and at the upper end by an assembly to which a cylindrical block 124 belongs, which acts as a valve and is attached to a central tappet 126 on which a spring 128 acts. These searches are usually the plunger downward pull to the block 124, 126, that is, in the Lagi _s in the .gebildete of the bore 121 is sealed chamber. The tension of the spring 128 can be adjusted by turning a nut 129 which is screwed onto the plunger 126 at the bottom. To adjust the nut, the cover 122 must be unscrewed. If the compression chamber formed at bore 50 is pressurized in normal operation, then

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neither liquid enters the chamber of the piston 64 formed by the bore 121, nor does liquid exit from it. But if the press container is relaxed _s the piston 64 thus goes down, then by a pressure difference between the interior of the piston 64 and the isostatic fluid is caused in the bore 50th If this pressure difference reaches a certain limit, then the higher pressure in the chamber of the piston 64 compresses the spring 128 and pushes the plunger with the block 124 upwards, so that pressure fluid flows out of the bore 121 through a longitudinal groove of the plunger 126 and into the upper one Front side of the piston 64 can emerge. The pressure limit at which this happens is selected so that this process only occurs when the volume of liquid in the bore 50 has suffered a specific leakage loss. In this way, the leakage loss due to the liquid emerging from the bore 121 of the piston 64 is compensated for when the piston 64 is pulled down and made ready for the next compression process. The cylindrical block 124 can be secured against rotation by a pin 130 so that it does not rotate when the nut 129 is adjusted.

Fig. 6 shows how the compression process and the relaxation is controlled hydraulically. Two separate pumps 204 and 202 are driven by a motor 200, which can have an output of 37 KW. The pump 202 is a vane pump having a non-adjustable flow rate of for example 80 1 per minute, and the pump 204 is a piston pump with a non-variable flow rate, which may be 90 per 1 minute _o If the press container is pressurized, then act initially Both pumps and feed the cylinder in which the larger piston 70 moves. If this moves upwards with reference to FIG. 6, then it in turn drives the smaller piston 64, which pressurizes the isostatic unit. A line runs from the pressure side of the pump 202 to a magnetically switchable control slide 208. From this

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leads a line 206 via a check valve 212 to a Line 214. This same line is also fed by pump 204. The line 214 * runs to a magnetically switchable one Control slide 216. If this control slide is in its left position with reference to FIG. 6, then he connects the line 214 with a line 218, and this leads to the cylinder of the piston 70, whereby this and the Pistons 64 are driven in the direction of the arrow to the isostatic Pressurize the aggregate.

When this pressure in the feed lines has reached about 140 atmospheres, a pressure relief valve 220, its closure piece, opens is displaceable by the pressure in a branch line 221 against the force of a spring, and connects the Line 210 and through this the pump 202 with a discharge line leading back to the storage container 222. This pressure drop in the line 210 reduces the amount of liquid with which the piston 70 acts in the last section of its pressure stroke will. This is because in this time segment the lines 214 and 218 are only supplied by the pump 204. This happens until the maximum pressure of, for example, 196 atmospheres is reached. When that happens, a pressure relief valve speaks on and allows the excess flow to flow back to the reservoir, while the preferred maximum pressure in the lines 214 and 218 is maintained. The pressure relief valve 224 is hydraulically adjustable. Because his locking piece, that on the one hand is acted upon by the pressure in the line 214, is subject to a pressure on its other side, which is caused by a Pressure relief valve 226 or pressure relief valve 228 or pressure relief valve 230, whichever of the three is supplied Pressure relief valve is selected by a magnetically switchable spool 232. If this control slide 230 takes the position shown in Fig. 6, then it selects the pressure relief valve 228 from. This then determines who is on the line

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prevailing maximum pressure. This maximum pressure acts on a pressure-sensitive switch 234. If it senses the maximum pressure off, then it switches on a timer which, after a pause, switches the control slide 232 in such a way that that this now selects the pressure relief valve 230. This initiates the relaxation, with the main feed line initially 214 through a throttle connection to a drain line the pressure is released to the extent that the pressure drops to about 70 atii, for example. The time at which this happens can be determine so that the next switching process can be initiated at this point in time by a timer. This switches the solenoid control slide 2l6, namely in the position shown in FIG. This leads to the fact that the piston 70 receiving Cylinder is suddenly switched to drain, but chamber 238 is connected to line 214. As a result will be the two pistons 70 and 64 quickly withdrawn from the press container. Once this retreat is over, it speaks to it a limit switch (not shown) on. This switches the control spool 232 into the position in which it is the Selects pressure relief valve 226. This has the consequence that the liquid from the pressure relief valve 224 is unthrottled back to the reservoir can flow. As a result, the operating height of the pressure relief valve 224 is reduced to a minimum of about 3 »5 atmospheres. As a result, the pressure in the entire hydraulic system is reduced to such an extent that unnecessary throttling and There is no overheating of the liquid in the system and when the system is idling between the individual compression processes Performance is saved.

After complete retraction of the two pistons 70 and 64 and after opening the press container, the control slide 208 becomes magnetic switched and connects the pressure line 206 of the pump 202 with a line 240 that feeds the hydraulic motor that the Arm 42, Fig. 2, drives. This hydraulic motor 300 is shown in FIG. 7. It is a motor with vane piston 302,

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which oscillate back and forth in chambers 304 which are delimited by fixed radial walls 306. If the vanes 302 are acted upon on one side or the other, the shaft 308 of the hydraulic motor is thereby driven in one sense or in the other. This shaft is coupled to the arm 42, Fig. 2 _S.

Whether the hydraulic motor 300 is in one or the other rotates in the other direction is controlled by a spool 310 determined, which is magnetically switchable. When switching this Control slide to the right with reference to FIG. 7, it connects the pressure line 240 with a line 312 leading to the chambers 304 leads. As a result, the wings 302 are acted upon so that they swing clockwise. If the reversing valve 310 is switched to the left with reference to FIG. 7, then the Pressurized fluid of about 84 atmospheres is fed to a separate conduit 314 through which the other sides of the two wings be applied. The wings then swing counterclockwise. In both cases, the hydraulic fluid flows from the Line 312 or line 314 to the hydraulic motor via one each Check valve 315

The pivoting of the holder 14 of the two pressure-resistant cylindrical bodies 10 caused by the hydraulic motor 300 and takes about 1 second, takes place at high speed Angular path braked, under control by a pressure relief valve 3l6 _? whose pressure limit can be adjusted between a high value and a low value. When the hydraulic motor has covered half the way, a limit switch is switched and this switches the pressure relief valve 3l6 to the lower pressure limit. This is done by energizing a magnetically switchable control valve 318

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If this assumes the position shown in Fig. 7, then it sets the pressure relief valve 316 to the lower pressure limit, so that the lower pressure prevails in the feed line 240. With this, the Fitigel 302 are then acted upon by the Hydraulic motor draining fluid flowing through blades 302 is displaced, is passed through throttle valves 320, which have a braking effect on the hydraulic motor 302. During the first Half of the oscillation of the blades 302, the high feed pressure ensures that overpressure valves 322 are switched to free flow are and therefore close the throttle valves 320 briefly and allow the unthrottled outflow of the liquid from the hydraulic motor. However, as soon as the reversing valve 318 through the limit switch is switched over, so that the lower pressure then prevails in the main feed line 240 and in the line 314 or 312, then the corresponding pressure relief valve 322 is switched to the position in which it prevents the flow. Then the from Fluid flowing out of the hydraulic motor flow through the relevant throttle valve 320.

The described embodiment of the invention can be modified in many ways.

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Claims (10)

PATENT CLAIMS 1.) Isostatic press, in particular for compacting metal powder, with a press mold (56, 58) receiving the substance to be compacted, the walls of which are deformable and which is located in a continuous axial bore of a pressure-resistant cylindrical body (10) during the pressing process at its two ends by a respective closure bodies (52, 5 ^) can be closed, said record during the pressing two spaced stringer plates _(l8? 20) the flameproof cylindrical body (lO) between them in a position in the said body is movable by a feed drive, characterized by a compression means (64) which extends through one (5 ^) of the two closure bodies and has a compressing effect on a substantially self-contained isostatic unit (62, 66) located in the bore, so that (A) the two closure body (52 _S 5 ^) outward in opposite directions to the plates (l8, 20) are expandable, whereby a hermetic seal between the pressure-resistant body (lO) and the spar plates (l8, 20) while maintaining a Hermetic seal between the closure body (52, 5 ^) and the pressure-resistant body (10) is achieved and (b) a relatively strong isostatic force is exerted on the substance (60) in the mold. 2. Press according to claim 1, characterized in that the Verdxchtungsmxttel from a in a bore (65) of the closure body (54) guided piston (64) and from a outside of the pressure-resistant body (lO) arranged power amplifier (70, 7l) is formed, which increased the driving force acting on the piston (64) 409830/0731 3. Press according to claim 2, characterized in that the pressure-resistant body (10) between that mentioned in claim 1 Place and a place located away from the spar plates is movable, where he with the material to be compacted through a loading device (24) loading this substance into the mold (56, 58) and after the pressing process by a Discharge device (26) is unloaded. 4. Press for compacting a powdery material (60) in a mold (56, 58) with deformable walls, which is suspended in a chamber of a pressure-resistant body (10), characterized in that the mold (56, 58) is supported by a holder (90) is suspended in the chamber (50) in such a way that it can follow a limited outward movement of the closure body (52) forming a chamber cover with increasing internal pressure and that when this closure body (52) is displaced into the closed position, the opening of the chamber is opened by a The seal (91) arranged on the holder (90) can be hermetically closed and that a plug (80) which closes the mold (56, 58) is connected to the closure body (52) and is therefore removed from the mouth of the mold (56, 56) when the chamber is opened. 58) is pulled out _o 5. Press according to claim 4, characterized by a piston (64), which can be advanced through a bore (65) of a closure body (5 ^) which closes the chamber and compresses it acts on an isostatic unit (62) located in the chamber without an isostatic unit (62) under high pressure for this purpose standing fluid would have to be introduced into the chamber (50) from an external source. 6. Press according to claim 5 »characterized in that the piston (6k) displaceable in the bore of the closure body (5 ^) can be driven by a power amplifier in the form of a second piston (70) having a larger diameter, 409830/0731 which is guided in a chamber of the press frame (72), and that the piston (64) guided in the closure body (54) is in such a way inside a pressure-resistant body (10) that forms the KamiEs: is supported that this pressure-resistant body is displaceable relative to the frame (72), 7. Press according to claim 4, 5 or 6, characterized in that the holder (90) is formed by a bushing which can be suspended in a bore (50) of the pressure-resistant body (10) forming the chamber, in order to have the shape to absorb and support the deformable walls _? this socket being open at one end so that the plug can be inserted through it. 8. Press according to any one of claims 4 to 7? characterized by a hydraulic control circuit (Figo 6) with one of the pressure relief of the chamber serving switching means (.232, 216), which in turn contains a switching means (232) by which the speed of the pressure relief is initially relatively low and then increased _o 9 »Press according to any one of claims 4 to 8, in which the Seal (91) when opening and closing the chamber remains in place and is effective against high pressure, and that the Closure body (52) has no high pressure seal. 10. booster for exerting a pressing force _s featured on An in-a chamber pressed material characterized in that an amplifier body (64) in the wall (LO) a pressure chamber (50) can be installed in such a manner _s to communicate with this pressure chamber, by a drive (70, 7i) into the chamber is vorschiebfoar in order to put the material contained therein under pressure, and that the amplifier body (64) carries a filling device (i20, 121, 124, 126 _S 128) to automatically one introduce a measured amount of the fluid into the chamber when the booster body is withdrawn therefrom. 409830/0731