NO176560B

NO176560B - Method and apparatus for pressure-based die casting

Info

Publication number: NO176560B
Application number: NO905317A
Authority: NO
Inventors: Hans Ivansson
Original assignee: Tour & Andersson Ab
Priority date: 1988-06-13
Filing date: 1990-12-10
Publication date: 1995-01-16
Also published as: NO905317D0; NO905317L; NO176560C

Description

Oppfinnelsen angår en framgangsmåte for presstøping som angitt i den innledende del av patentkrav 1 og en anordning for bruk ved presstøping i henhold til den innledende del av patentkrav 6. The invention relates to a procedure for die casting as stated in the introductory part of patent claim 1 and a device for use in die casting according to the introductory part of patent claim 6.

Bakgrunn Background

For å oppnå en rasjonell anvendelse av kapasiteten til en presstøpemaskin, blir den ofte brukt til å støpe ulike objekter. For å kunne støpe slike objekter, dvs. for å kunne skifte fra støping av en viss type objekt til en annen type objekt, blir vanligvis det nedre såvel som det øvre stemplet samt det rør-formete fylle-kammeret skiftet ut i likhet med forma og røret, som omgir det nedre stemplet. Dette er selvsagt alltid en tidkrevende og kostbar framgangsmåte, noe som er lite ønskelig. Støpeprosedyren er også hindret på denne måten, siden f. eks. konstante endringer i støpestemplenes diameter, anvendt i øyeblikket, resulterer i varierende trykk, som vanligvis ikke er akseptabelt eller selv oppnåelig. Som en konsekvens må det utføres en endring i støpestemplets diameter, dvs. utskiftning av et støpestempel, med en tilhørende endring i maskinens presstrykk. Dette leder automatisk til en stor risiko ved at personell vil kunne gjøre feilberegninger eller feiljusteringer som angår trykket, med det resultat at støpestykkene får redusert kvalitet eller at de må kasseres. Dessuten kan ikke alltid uønskete luftlommer unngås i de kjente presstøpemaskiner. In order to achieve a rational application of the capacity of a die casting machine, it is often used to cast various objects. In order to be able to cast such objects, i.e. to be able to change from casting a certain type of object to another type of object, the lower as well as the upper piston as well as the tube-shaped filling chamber are usually replaced in the same way as the mold and the tube, which surrounds the lower piston. This is of course always a time-consuming and expensive procedure, which is not desirable. The casting procedure is also hindered in this way, since e.g. constant changes in die diameter, currently employed, result in varying pressures, which are usually not acceptable or even achievable. As a consequence, a change in the diameter of the die must be made, i.e. replacement of a die, with a corresponding change in the press pressure of the machine. This automatically leads to a large risk in that personnel will be able to make miscalculations or misadjustments concerning the pressure, with the result that the castings are of reduced quality or that they have to be discarded. Furthermore, unwanted air pockets cannot always be avoided in the known compression molding machines.

Formål Purpose

Formålet med oppfinnelsen er å forbedre og utvikle de kjente framgangsmåtene for presstøping og anordningene ved de ovennevnte henseende. Et annet formål med oppfinnelsen er også å bidra til å fremme teknikken innenfor dette området i ulike henseender og å skape muligheter for en rasjonell teknikk og produkter som har en tilfredstillende og jevn kvalitet. The purpose of the invention is to improve and develop the known procedures for die casting and the devices in the above-mentioned respects. Another purpose of the invention is also to contribute to promoting the technique within this area in various respects and to create opportunities for a rational technique and products that have a satisfactory and uniform quality.

Oppfinnelsen The invention

Disse formålene oppnås med en framgangsmåte ifølge den karakteriserende del av patentkrav 1 og en anordning for presstøping ifølge den karakteriserende del av patentkrav 6. Ytterligere fordelaktige trekk framgår av de tilhørende uselvstendige kravene. These objects are achieved with a method according to the characterizing part of patent claim 1 and a device for pressure casting according to the characterizing part of patent claim 6. Further advantageous features appear from the associated independent claims.

Figur 1 viser en anordning i henhold til oppfinnelsen i dens støpeposisjon, det vil si etter lukking av formene og fylling av flytende metall men før selve støpingen; Figure 1 shows a device according to the invention in its casting position, that is to say after closing the molds and filling with liquid metal but before the casting itself;

figur 2 viser anordningen i figur 1 etter at støpingen er utført; og figure 2 shows the device in figure 1 after the casting has been carried out; and

figur 3 viser anordningen i figur 1 etter at de produserte støpestykkene er tatt ut klare til å returneres til startposisjonen for den neste støpesyklus. figure 3 shows the device in figure 1 after the produced castings have been taken out ready to be returned to the starting position for the next casting cycle.

I figurene er det vist en anordning 1 i sin helhet i henhold til oppfinnelsen, hvor anordningen omfatter ei masMnramme 2, som hovedsakelig omfatter ei øvre bæreplate 3, hvorfra f.eks. fire maskin-støtter 4 er rettet nedover, hvor den nedre enden av de respektive støttene bæres av en nedre maskinbenk 5, som igjen bæres av føtter 6. The figures show a device 1 in its entirety according to the invention, where the device comprises a masMnramme 2, which mainly comprises an upper support plate 3, from which e.g. four machine supports 4 are directed downwards, where the lower end of the respective supports is supported by a lower machine bench 5, which in turn is supported by feet 6.

Den øvre bæreplata 3 bærer f.eks. fire hydrauliske form-sylindere 7, som er The upper support plate 3 carries e.g. four hydraulic form-cylinders 7, which are

konstruert for å åpne og lukke ei form, som er beskrevet i den etterfølgende teksten, ved hjelp av et forsåvidt kjent kontrollsystem (ikke vist). Stempelstenger 9 stikker ut fra form-sylindere 7 nedover gjennom boringer 8 i bæreplata, og en øvre maskinbenk 10 er hengt opp i de nedre endene av stempelstengene og er flyttbar langs maskin-støttene 4 ved hjelp av ledebøssinger 11. designed to open and close a mold, which is described in the following text, by means of an apparently known control system (not shown). Piston rods 9 protrude from form cylinders 7 downwards through bores 8 in the carrier plate, and an upper machine bench 10 is suspended from the lower ends of the piston rods and is movable along the machine supports 4 by means of guide bushings 11.

Et åk 13 er posisjonert over den øvre maskinbenken 10 ved hjelp av avstandsstenger 12, i en avstand fra og fortrinnsvis sentrert over dets maskin-benk. Åket 13 bærer en øvre stempelsylinder 14, som rager oppover gjennom en åpning IS i bæreplata, hvor åpningen er stor nok til at åket i dets posisjon i henhold til figur 3 kan passere denne åpningen. A yoke 13 is positioned over the upper machine bench 10 by means of spacer bars 12, at a distance from and preferably centered over its machine bench. The yoke 13 carries an upper piston cylinder 14, which projects upwards through an opening IS in the support plate, where the opening is large enough for the yoke in its position according to Figure 3 to pass this opening.

Ei stempelstang 17 rager nedover gjennom en åpning 16 i åket 13 og er utrustet med et øvre stempel 18, som er ført inn i et rør 19, som er festet til den øvre maskinbenken 10, for derved å lukke et fyllkammer 20 og er utrustet med ei fylletrakt 21, som er konstruert for å introdusere en viss mengde flytende metall. A piston rod 17 projects downwards through an opening 16 in the yoke 13 and is equipped with an upper piston 18, which is led into a tube 19, which is fixed to the upper machine bench 10, thereby closing a filling chamber 20 and is equipped with a hopper 21, which is designed to introduce a certain amount of liquid metal.

En øvre formdel 22 er festet til undersiden av den øvre maskinbenken, og dens underside er igjen utrustet med et øvre hulrom 23. An upper mold part 22 is attached to the underside of the upper machine bench, and its underside is again equipped with an upper cavity 23.

En nedre formdel 24 ligger an på en maskinbenk 5 og dens overside er på samme måte utrustet med et nedre hulrom 25. A lower mold part 24 rests on a machine bench 5 and its upper side is similarly equipped with a lower cavity 25.

Ei holdeplate 27 er montert under og i avstand fra maskinbenken 5 via avstandsstenger 26 for ejektorsylindere 28, montert under holdeplata. De tilhørende stempelstengene 29 er rettet oppover gjennom åpninger 30 i holdeplata 27 for sammen å bære ei bru 31, som er montert for å kunne forflyttes mellom maskinbenken 5 og holdeplata 27. Brua 31 bærer igjen f.eks. 2-12 ejektorstenger 32, som er rettet oppover gjennom boringer 33 i maskinbenken 5 for, over sistnevnte, å kunne bære ei felles forbindelsesplate 34 med øvre ejektorplater 35 og ejektorpinner 37, som er ført inn fra ejektorplatene inn i den nedre form-delen 24 i styrehull 36 i sistnevnte, hvorved støpestykkene etter støpeprosedyren kan støtes ut ved hjelp av ejektorpinnene når formene er åpnet. A holding plate 27 is mounted below and at a distance from the machine bench 5 via distance rods 26 for ejector cylinders 28, mounted below the holding plate. The associated piston rods 29 are directed upwards through openings 30 in the holding plate 27 to together support a bridge 31, which is mounted to be able to be moved between the machine bench 5 and the holding plate 27. The bridge 31 again carries e.g. 2-12 ejector rods 32, which are directed upwards through bores 33 in the machine bench 5 in order, above the latter, to be able to carry a common connection plate 34 with upper ejector plates 35 and ejector pins 37, which are introduced from the ejector plates into the lower mold part 24 in guide holes 36 in the latter, whereby the castings after the casting procedure can be ejected by means of the ejector pins when the molds are opened.

En nedre stempelsylinder 38 er montert under brua 31 i en sentrert posisjon, hvor det i sylinderen er montert et stempel 39 hvorfra det stikker ut ei stempelstang 40 som rager gjennom åpninger 41 og 42 i henholdsvis brua 31 og maskinbenken 5 for i sin frie ende å kunne bære et nedre stempel 43, som er ledet inn i en bøssing 44 i den nedre formdelen og i en bøssing 45, konstruert som en fortsettelse av bøssing 44 i den øvre formdelen. Røret 19 og bøssingen 45 kan også konstrueres som en enhet. Bøssingene kan også kjøles direkte eller indirekte på en i og for seg kjent måte, og er ikke vist i nærmere detalj i denne forbindelse. Imidlertid er kjølekanaler indikert felles med 46 i figur 1. A lower piston cylinder 38 is mounted under the bridge 31 in a centered position, where a piston 39 is mounted in the cylinder from which a piston rod 40 protrudes, which protrudes through openings 41 and 42 in the bridge 31 and the machine bench 5, respectively, in order at its free end to could carry a lower piston 43, which is guided into a bushing 44 in the lower mold part and in a bushing 45, constructed as a continuation of bushing 44 in the upper mold part. The tube 19 and the bushing 45 can also be constructed as a unit. The bushings can also be cooled directly or indirectly in a manner known per se, and are not shown in further detail in this connection. However, cooling channels are indicated in common with 46 in Figure 1.

Også nedre stempel 43 og stempelstang 40 kan med fordel være avkjølt, og i den sammenheng kan en forbindelse 47 fra stempel 39 til en kjøleinnretning, ikke vist, være rettet nedover gjennom sylinder 38. Lower piston 43 and piston rod 40 can also advantageously be cooled, and in that context a connection 47 from piston 39 to a cooling device, not shown, can be directed downwards through cylinder 38.

Anordningen som er beskrevet på denne måten kan anvendes på følgende måte: figur 1 viser som nevnt anordningen i dens støpeposisjon hvor formene er lukket, f.eks. med et innesluttet formstykke 48. En viss tilmålt mengde flytende metall, fortrinnsvis en legering uten jern, har allerede blitt fylt inn i kammer 20 og er betegnet ved 49. Overflata av det fylte metallet rekker med fordel fram til den nedre kanten av trakta 21 eller muligens en liten distanse under den samme, forutsatt at en svært liten påkrevet mengde luft lukkes mellom det øvre stemplet og metallet under den etterfølgende støpeoperasjon. For å oppnå denne presise justering er en nødt til å legge vekt på den tilmålte mengde metall så vel som, og dette er det viktigste, posisjonen for det nedre stemplet, som i henhold til oppfinnelsen er justerbart i en påkrevet vertikal posisjon, for å kunne tillate en eksakt beregnbar fylling av metall, og en optimal utførelse av støpeoperasjonen, med minst mulig overflødig mengde. Det nedre stemplets posisjon justeres som indikert på en høvelig måte, f.eks. ved hjelp av et programmerbart kontrollpanel på elektronisk vis. The device described in this way can be used in the following way: figure 1 shows, as mentioned, the device in its casting position where the molds are closed, e.g. with an enclosed mold piece 48. A certain measured amount of liquid metal, preferably an alloy without iron, has already been filled into chamber 20 and is denoted by 49. The surface of the filled metal advantageously reaches up to the lower edge of the tract 21 or possibly a small distance below it, provided that a very small required amount of air is enclosed between the upper piston and the metal during the subsequent casting operation. To achieve this precise adjustment one has to pay attention to the measured amount of metal as well as, and this is the most important, the position of the lower piston, which according to the invention is adjustable to a required vertical position, in order to be able allow an exact calculable filling of metal, and an optimal performance of the casting operation, with the least possible excess amount. The position of the lower piston is adjusted as indicated in an appropriate manner, e.g. using a programmable electronic control panel.

Det øvre stemplet blir deretter senket til umiddelbart over metalloverflata, i hvilken posisjon anordningen programmeres på en slik måte at det øvre stemplet og det nedre stemplet starter en felles bevegelse nedover inntil det nedre stemplet har kommet fram til en posisjon i henhold til figur 2, hvorved det nedre stemplet stanser, dvs. umiddelbart under fødekanalene 51 mellom formdelene. Stemplenes hastighet under den beskrevne bevegelsen er fortrinnsvis den samme. Når det nedre stemplet har stanset, vil det øvre stemplet bevege seg videre nedover til en posisjon i henhold til figur 2, for å bringe alt innfylt metall videre og for å presse metallet inn i hele forma, hvoretter en viss overflødig mengde, en såkalt pressbrikett 50, blir igjen i den nedre del av fyllkammeret. The upper piston is then lowered to immediately above the metal surface, in which position the device is programmed in such a way that the upper piston and the lower piston start a joint downward movement until the lower piston has arrived at a position according to figure 2, whereby the lower piston stops, i.e. immediately below the feed channels 51 between the mold parts. The speed of the pistons during the described movement is preferably the same. When the lower punch has stopped, the upper punch will move further down to a position according to Figure 2, to bring all the filled metal forward and to press the metal into the entire mold, after which a certain excess amount, a so-called press briquette 50, remains in the lower part of the filling chamber.

Når metallet har størknet i forma, etter f.eks. 2-20 sekunder, blir formsylinderene 7 aktivert hvoretter stempelstengene 9 trekker den øvre maskinbenken 10 oppover When the metal has solidified in the form, after e.g. 2-20 seconds, the form cylinders 7 are activated after which the piston rods 9 pull the upper machine bench 10 upwards

med øvre formdel 22 hvorved oversiden av støpestykkene blir avdekket. For å fjerne briketten 50 fullstendig fra fyllkammeret 20, blir den øvre stempelsylinderen 14 holdt aktiv, hvor den følgelig vil skyve stempelstanga gradvis utover, når maskinbenken 5 er beveget oppover, hvor det øvre stemplet hele tiden blir presset mot briketten, inntil den øvre maskinbenken har nådd fram til dens øvre startposisjon i henhold til figur 3, hvorved den øvre stempelsylinderen aktiveres for å skyve stemplet til posisjonen vist i figur 3. Stempelstanga 17 kan selvsagt skyves innover noe tidligere, f.eks. så snart en relativ posisjon er nådd, hvorved briketten har forlatt fyllkammeret. with upper mold part 22 whereby the upper side of the castings is exposed. In order to completely remove the briquette 50 from the filling chamber 20, the upper piston cylinder 14 is kept active, where it will consequently push the piston rod gradually outwards, when the machine bench 5 is moved upwards, where the upper piston is constantly pressed against the briquette, until the upper machine bench has reached its upper starting position according to Figure 3, whereby the upper piston cylinder is activated to push the piston to the position shown in Figure 3. The piston rod 17 can of course be pushed inward somewhat earlier, e.g. as soon as a relative position has been reached whereby the briquette has left the filling chamber.

Sylinderene 28 er nå aktiverte og brua 31 er løftet slik at endelig ejektorpinnene 37 følgelig er aktiverte, hvorved de produserte støpestykkene frigjøres fullstendig, også fra den nedre formdelen. Det nedre stemplet bidrar også til dette, siden dets sylinder er festet til brua, som resulterer i at også det nedre stemplet ved siden av ejektorpinnene forflyttes i forhold til den nedre formdelen. Når sylinderene 28 har returnert til deres startposisjon i henhold til figur 1, blir sylinder 38 aktivert hvorved dets stempel 39 løfter det nedre stemplet til en posisjon i henhold til figur 3, som er den samme som posisjonen vist i figur 1, og på denne måten kan det startes en ny støpesyklus. The cylinders 28 are now activated and the bridge 31 is lifted so that finally the ejector pins 37 are consequently activated, whereby the produced castings are completely released, also from the lower mold part. The lower piston also contributes to this, since its cylinder is attached to the bridge, which results in the lower piston next to the ejector pins also being displaced relative to the lower mold part. When the cylinders 28 have returned to their starting position according to Figure 1, cylinder 38 is activated whereby its piston 39 lifts the lower piston to a position according to Figure 3, which is the same as the position shown in Figure 1, and in this way a new casting cycle can be started.

Den frie endeoverflata av det nedre stemplet og fortrinnsvis også dets omgivende overflate er i henhold til en foretrukket utførelse av oppfinnelsen utrustet med et keramisk belegg for å hindre slitasje og/eller for i begrenset grad å framskaffe en varmeisolator. Veggen i fyllkammeret kan også være laget av et keramisk materiale. På denne måten vil metallet som ønsket kjøles i minimal grad i fyllkammeret, mens den termiske ekspansjon av røret 19 og det nedre stemplet også begrenses tilsvarende, noe som er ønskelig for å opprettholde de påkrevde grensene. Det øvre stemplet kan også kjøles for å oppnå en raskere størkning, og dets omgivende overflate kan, for å hindre slitasje, være utrustet med et keramisk belegg. According to a preferred embodiment of the invention, the free end surface of the lower piston and preferably also its surrounding surface is equipped with a ceramic coating to prevent wear and/or to provide a heat insulator to a limited extent. The wall of the filling chamber can also be made of a ceramic material. In this way, the metal will be cooled as desired to a minimal degree in the filling chamber, while the thermal expansion of the tube 19 and the lower piston is also limited accordingly, which is desirable in order to maintain the required limits. The upper piston can also be cooled to achieve a faster solidification, and its surrounding surface can, to prevent wear, be equipped with a ceramic coating.

For å oppnå best mulig støpekvalitet etterstreber den foreliggende oppfinnelsen, med alle dens karakteriserende trekk, å oppnå en overensstemmende kontroll av størkningen fra utsiden og innover, hvor f.eks. briketten SO i denne forbindelse holdes så varm som mulig ved dens underside og ved de tilstøtende sider, mens nedkjøling og dermed størkning tillempes fra oversiden. Undersiden eller den frie ende-overflata av det øvre stemplet kan også være laget av et materiale med en tilfredsstillende termisk ekspansjonskoeffisient, f.eks. legeringer av Mo og særlig en slik legering med handelsnavnet TZM (ca. 0.5% Ti, 0.07% Zr, 0.01% C og resten Mo, jfr. f.eks. Metallwerk Plansee AG, Reutte, Østerrike). In order to achieve the best possible casting quality, the present invention strives, with all its characterizing features, to achieve a consistent control of the solidification from the outside in, where e.g. the briquette SO in this connection is kept as warm as possible at its underside and at the adjacent sides, while cooling and thus solidification is applied from the upper side. The underside or free end surface of the upper piston may also be made of a material with a satisfactory coefficient of thermal expansion, e.g. alloys of Mo and in particular such an alloy with the trade name TZM (approx. 0.5% Ti, 0.07% Zr, 0.01% C and the rest Mo, cf. e.g. Metallwerk Plansee AG, Reutte, Austria).

Mens overgangsperioden fra en støpetype til en annen er 3 til 4 timer i en vanlig støpemaskin, er tilsvarende overgangsperiode for den foreliggende oppfinnelsen så kort som 10 til 15 minutter. Således muliggjør den foreliggende oppfinnelsen viktige tidsbesparelser og forbedringer ved framgangsmåten. While the transition period from one casting type to another is 3 to 4 hours in a conventional casting machine, the corresponding transition period for the present invention is as short as 10 to 15 minutes. Thus, the present invention enables important time savings and improvements in the method.

Claims

1. Method of die casting with rational use of the capacity of a die casting machine for various objects, where liquid metal (49) is filled in a filling chamber (20) in a vertically movable upper machine bench (10) with an upper mold part (22) mounted below the same , while the metal is temporarily supported by a lower piston (43), which is guided in a stationary lower mold part (24), characterized in that liquid metal in an amount equivalent to the requested casting including a required excess amount is measured, where the lower piston (43) before filling in the metal is brought to such an adjustable elevated position above the casting's height and where an upper piston (18), which is designed for pressure feeding the metal into the mold (22,24) contacts the metal surface when filling the chamber, mainly without any entrapment of air or with a certain entrapment of a smaller required amount of air in the filling chamber (20), whereby the lower piston ( 43) and the upper piston (18) together with the added metal are moved downwards at the same relative speed to the casting position for the lower piston (43), whereby the lower piston (43) stops and the upper piston (18) is moved further downwards and exposed for a continuous pressing pressure, until the casting operation is completed and the metal has solidified, whereby the produced casting is ejected by means of an ejector mechanism (29-37).

2. Method according to claim 1, characterized in that the position of the lower piston (43) is adjusted and indicated electronically via a programmable control panel.

3. Method according to claim 1 or 2, characterized in that when the metal has solidified in the mold (22,24), the upper mold part (22) is pushed upwards while the produced castings are exposed, and a briquette (SO), which has remained in the filling chamber (20) is affected by the upper piston (18) and its cylinder (14) during this upward pushing movement by the piston rod (17) in the cylinder (14) being pushed outwards at least to such a distance that the briquette (SO) leaves the filling chamber (20), whereby the upper piston cylinder ( 14) is activated to push the piston rod (17) inward to a starting position for a new casting cycle.

4. Method according to one of claims 1 to 3, characterized in that the lower piston (43) in connection with or at the same time as the raising of the same caused by the movement of its cylinder (14), is moved upwards to the calculated or programmed starting position for a new molding cycle.

5. Method according to one of claims 1 to 4, characterized in that the inner wall of the filling chamber (20) and/or the lower piston (43) is thermally insulated, and/or that at least the free end surface of the upper piston is made sufficiently thermally conductive, whereby the thermal insulation is preferably carried out by means of a ceramic material, while the thermal conduction advantageously takes place by means of a molybdenum alloy, e.g. an alloy with the trade name TZM (Mo-0.5Ti-0.07Zr-0.01C).

6. Device designed to carry out the method according to claim 1, comprising a stationary lower machine bench (5) provided with a stationary lower mold part (24), which is designed to cooperate with an upper mold part (22), mounted under an upper machine bench ( 10), vertically movable by means of hydraulic cylinders (7), whereby the machine bench together with the upper mold part exhibits a filling chamber (20) designed to receive liquid metal to be cast, where a hydraulic cylinder-actuated upper piston (18 ) and a hydraulic cylinder-actuated lower piston (43) passed through the lower mold part (24) designed to temporarily carry the filled liquid metal, characterized in that the lower piston (43) and the upper piston (18) are connected by an adjustment device, such as an electronic programmable control panel, so that the upper piston (18) at the start of a casting operation can contact the surface of the molten metal located in the filling chamber (20) located above the casting position substantially free of entrapped air, and is fed together with the lower piston (43), and molten metal (49) located between the pistons, to the casting position whereby the upper piston (18) is designed to continue its downward moving and pressing molten metal between the mold parts (22,24); and an ejector mechanism (29,37) designed to remove solidified castings.

7. Device according to claim 6, characterized in that the lower machine bench (5), supported by feet or similar (6), by means of machine supports (4) together with the upper machine bench (10) which is vertically adjustable, supports an upper support plate (3), to which cylinders ( 7) are mounted, designed to drive the upper mold part (22), the upper machine bench (10) carries a yoke (13) by means of spacer bars (12), on which the upper piston cylinder (14) with its upper piston (18) is mounted, where the resulting unit is preferably vertically movable through an opening (15) in the carrier plate (3).

8. Device according to claim 6 or 7, characterized in that a holding plate (27) is mounted under the lower machine bench (5), at a distance from it by means of spacer bars (26), where ejector cylinders (28) are mounted under the holding plate and are designed to be able to be moved vertically by by means of a bridge (31) mounted between the lower machine bench (5) and the holding plate (27) and which carries a lower piston cylinder (38), mounted below the bridge (31), as well as upper ejector rods (32), which project through it the lower machine table and which again preferably carries a common connecting plate (34) as well as ejector plates (35), preferably mounted in groups, and ejector pins (37), which are inserted into the lower mold part (24).

9. Device according to one of claims 6 to 8, characterized in that the mold parts (22,24) and the upper machine bench (10) and/or the lower piston (43) and the upper piston (18) are each equipped with cooling devices (46,47).

10. Device according to one of claims 6 to 9, characterized in that the filling chamber (20) and/or preferably the free end surface and the surrounding surface of the lower piston (43) are made of a material and are equipped with a coating which reduces wear and/or contributes to heat insulation, in particular made of a ceramic material, and/or that the upper piston (18), especially its free end surface, is made of or is coated with a material that exhibits a satisfactory heat conduction coefficient, preferably an alloy of molybdenum, e.g. the alloy with the trade name TZM (Mo-0.5Ti-0.07Zr-0.01C).