EP0030669A1 - Apparatus for low-pressure casting - Google Patents

Abstract

Automatically controlled low-pressure casting process, in which in a casting station (G) a first (1) a number of molds (1, 1 ', 1 ") arranged at regular intervals on a rotary table (21), through the riser pipe (6) of a low-pressure casting furnace (2) is filled with molten metal (3) while simultaneously immersing a second opened mold (1 ') in an immersion station (T) in an immersion bath (20) and at the same time in a preparation station (V) a third partially opened mold (1 " ), for which casting is being prepared. The molds are then moved on a circular path until further molds have reached the described stations (G, T, V), whereupon the processes are repeated and the filled mold (1) in each case before reaching the immersion station (T) in a demolding station ( E) automatically opened and emptied, the one (1 ') coming from the immersion bath (20) is tilted into a horizontal position, and the one (1 ") prepared for the casting is pivoted vertically and lowered onto the furnace nozzle (7). Advantageously The movement of the molds (1, 1 ', 1 ") is interrupted when one of them is in the demolding station (E).

Description

The object of the invention is to fully or at least largely automate the known manual casting processes in which a number of casting molds arranged on a casting carousel are successively filled with metal, i.e. To limit the use of human labor, for example, to the simple insertion of mold cores and the monitoring of the device, or to completely forego human activity during the course of the process.

To fill the molds moving on a circular path, the invention uses a low-pressure casting furnace known per se (DE-PS 20 41 588, DE-C _S 21 28 425) in a modification which has been adapted in particular with regard to the automatic function of the invention.

• a) In einer Gießstation wird eine erste einer Anzahl von in gleichmässigen Abständen auf einem Drehtisch angeordneten Kokillen, während sie über einem an sich bekannten Niederdruckofen steht, durch dessen Steigrohr mit geschmolzenem Metall gefüllt, während gleichzeitig eine zweite, geöffnete Kokille in einer Eintauchstation automatisch in ein Tauchbad eingetaucht und wieder aus dem Bad herausgehoben wird und ebenfalls gleichzeitig in einer Vorbereitungsstation eine dritte, teilgeöffnete Kokille, z.B. durch Einlegen von Gusskernen für den Guss vorbereitet wird.
• b) Danach werden die Kokillen auf einer Kreisbahn bewegt, bis weitere Kokillen in den beschriebenen Stationen an^ge-langt sind, wobei sich die Vorgänge wiederholen und jeweils die gefüllte Kokille vor Erreichen der Eintauchstation in einer Entformungsstation automatisch geöffnet und entleert, die aus dem Tauchbad kommende in eine waagrechte Lage gekippt und die für den Guss vorbereitete geschlossen in die Senkrechte geschwenkt und auf die Ofendüse abgesenkt wird.

To achieve this object, the invention proposes an automatically controlled low-pressure casting process, which is characterized by the following process steps:

• a) In a casting station, a first of a number of in uniform Ab stood on a rotary table arranged molds, while it stands over a known low-pressure furnace, filled with molten metal through its riser, while at the same time a second, opened mold is automatically immersed in an immersion station and lifted out of the bath again and also simultaneously in a preparation station, a third, partially open mold is prepared for casting, for example by inserting cast cores.
• b) Thereafter, the molds are moved on a circular path, are arrived e-bis more molds in the described stations ^g, wherein repeat the operations and respectively automatically open the filled mold before reaching the immersion station in a demolding station and discharged from the The immersion bath is tilted into a horizontal position and the one prepared for casting is swung into a vertical position and lowered onto the furnace nozzle.

Advantageously, the movement of the molds on the circular path is interrupted when one of them is in the demolding station.

For automatic and mark-free demolding of the castings, the opened mold can be subjected to violent vibration in the demolding station.

The invention also relates to a device for carrying out the aforementioned method, which is characterized by a turntable, on the periphery of which a number of identical or different molds with associated devices for automatic opening and closing, tilting, and lifting and lowering of the molds are arranged at regular intervals. and around which a casting station with a known low-pressure furnace with riser pipe and furnace nozzle, an immersion station with an immersion bath and a preparation station and between the casting furnace and the immersion bath are grouped a demolding station; a drive for moving the molds from station to station and a control system for automatically triggering the individual functions.

In order to adapt to the automatic operation of the device, the known low-pressure casting furnace is preferably provided with a siphon-like filling chamber, the connection of which to the metering chamber is below the lowest level of the molten metal, as a result of which an escape of the protective gas used as pressure medium for the casting during refilling of the oven is prevented.

The advantages of the invention lie not only in the saving of operating personnel, but at most a man for inserting the cores and the over of the system is necessary, but also in that it saves the workplaces that were physically exhausting, uncomfortable and also not physically demanding in the usual manual casting process with casting carousels, from which the invention is based, namely manual handling of the molten metal and the associated noise, heat and exhaust emissions. The invention thus also meets modern demands for humanization of the workplace and relief for the environment.

In addition, the adaptation of the low-pressure casting process to the automatic mode of operation according to the invention brings the advantages of a controllable mold filling, the control of the solidification in the base storage position of the casting, the limitation of the burn-up to a minimum and the reduction of the circulating proportion, a uniformly good one Casting quality, reduced risk of foaming due to casting under a protective gas atmosphere and metal savings in the gate and feed system.

• Fig. 1 und 2 in stark vereinfachter Darstellung einen Schnitt durch die Gießstation einer erfindungsgemäßen Vorrichtung mit dem Niederdruckgiessofen und auf dessen Steigrohr aufgesetzter Kokille.
• Fig. 3 eine stark vereinfachte Aufsicht auf eine erfindungsgemässe Vorrichtung zur Verdeutlichung der Anordnung der Giess-, Entformungs-, Eintauch- und Vorbereitungsstation.
• Fig. 4 einen den Fig. 1 und 2 entsprechenden Schnitt in etwas grösserem Maßstab, mit mehr Einzelheiten.
• Fig. 5 einen Schnitt entlang der Linie V - V in Fig. 4.
• Fig. 6 einen Schnitt entlang der Linie VI - VI in Fig. 4.
• Fig. 7 eine Aufsicht auf den Ofen der Fig. 4 mit Mehrfachdüse.
• Fig. 8 eine in Giessposition befindliche Kokillenanordnung, teilweise geschnitten.
• Fig. 9 eine Aufsicht auf den Gegenstand der Fig. 8.
• Fig.10 eine der Fig. 8 entsprechende Darstellung mit zum Auswerfen der Gussteile geöffneter Kokille.
• Fig.11 die Kokille in Tauchposition und in gegenüber Fig. 10 vergrössertem Maßstab.
• Fig. 12 eine Aufsicht auf die Eintauchstation.
• Fig. 13 eine den Fig. 8 und 10 entsprechende Darstellung der Kokillen in der Vorbereitungsstation und
• Fig. 14 eine Aufsicht auf die Vorbereitungsstation.

The invention is explained in more detail below with reference to the drawings using an exemplary embodiment. They represent:

• 1 and 2 in a highly simplified representation, a section through the casting station of a device according to the invention with the low-pressure casting furnace and mold placed on the riser pipe.
• Fig. 3 is a greatly simplified plan view of a device according to the invention to illustrate the arrangement of the casting, demolding, immersion and preparation station.
• 4 shows a section corresponding to FIGS. 1 and 2 on a somewhat larger scale, with more details.
• 5 shows a section along the line V - V in FIG. 4.
• 6 shows a section along the line VI - VI in FIG. 4.
• Fig. 7 is a plan view of the furnace of FIG. 4 with a multiple nozzle.
• Fig. 8 is a mold arrangement in the casting position, partially cut.
• 9 is a plan view of the subject of FIG. 8.
• 10 shows a representation corresponding to FIG. 8 with the mold open to eject the cast parts.
• 11 shows the mold in the diving position and on an enlarged scale compared to FIG. 10.
• Fig. 12 is a plan view of the immersion station.
• 13 shows a representation of the molds in the preparation station corresponding to FIGS. 8 and 10
• 14 is a top view of the preparation station.

1, 2, 4, 6 and 8, the mold 1, which consists of two halves 1a and 1b, is in the closed position in the casting station G (FIGS. 3 and 9) and is on the furnace nozzle of the low-pressure casting furnace 2 lowered. This is filled with molten metal 3 and has a cylindrical metering chamber 5 above the melting mirror 4, which is filled with a protective gas, for example nitrogen.

The placement of the mold 1 automatically increases the protective gas pressure in the metering chamber 5 by means of a magnetic valve, as a result of which the melting level 4 is lowered and the molten metal 3 slowly through the riser pipe 6 and the furnace nozzle 7, which, depending on the type and complexity of the castings to be produced, as usual, can be designed as an immersion or, as shown, as a multiple nozzle, into the cavities 8 of the mold 1 corresponding to the castings. The parameters of casting speed and casting time, which are decisive for void-free casting, can be used for different molds as part of the automatic control can be freely programmed.

After the time required for solidification has elapsed, the gas pressure is reduced again, and the non-solidified metal in the furnace nozzle drops, while the melting level 4 in the metering chamber rises at the same time. The protective gas removed from the dosing chamber during this process is absorbed without loss by a special container. After the casting process, the mold 1 is automatically lifted from the furnace.

The low pressure casting furnace 2 is designed as an induction channel furnace with a melting channel 9, coil 10 and iron yoke 11. The melting chamber of the induction channel furnace is formed here by the metering chamber 5 located above the channel 9.

In order to keep the melting level 4 at the same level for each casting, that is to say to compensate for the metal consumed during the casting process, a displacement body 12 is used, which is automatically readjusted by means of a rod 13 from a working cylinder 14, not shown, depending on the volume of the casting.

After a certain number of castings, the displacer 12 reaches a predetermined lowest position, in which a signal is triggered which signals the need to refill the casting furnace 2 and at the same time sets the displacer 12 in its uppermost position. The pouring furnace is filled with liquid metal via a _s i Filling chamber 15 arranged in a phonetic manner, the connection 16 of which to the metering chamber 5 lies below the lowest level 17 of the molten metal 3. This prevents the protective gas from escaping from the metering chamber 5 when the working cover 18 of the filling chamber 15 is opened. The direct connection of a melting furnace has proven to be an economical solution for a clean transfer of the melted material into the low-pressure casting furnace, which can be designed both as a fixed compressed-air-empty furnace and as a tilting furnace. So much metal is refilled through the filling chamber 15 until the melting mirror 4 has reached a predetermined height when the displacement body 12 is in the uppermost position.

During the above-described casting process, a second opened mold 1 'is located in an immersion station T (FIGS. 3, 10, 11, 12), where it is lowered from the raised position shown in FIG. 10 to the position shown in FIG. 11 immersion bath 20 contained in a plunge pool 19 is immersed.

The immersion bath, e.g. a size bath is equipped with an agitator and can also be preheated by a built-in heater (both not shown). The immersion depth and the immersion time are pre-programmed depending on the size of the mold so that the mold temperature remains constant.

After this time, the mold is raised again to the position shown in FIG. 10.

A third mold 1 "is located during the above-described processes in the partially opened position shown in FIG. 13 and tilted into the horizontal position in a preparation station V (FIGS. 3 and 14) in which an operator, who is primarily responsible for the smooth operation of the automatic operations are monitored, the mold can be blown out with compressed air and the casting cores can be inserted, provided that these operations are not carried out automatically.

After completion of the longest of the three aforementioned processes, with the rotary table 21 carrying the mold standing still, it is driven in the direction of arrow A, and with it the molds 1, 1 ', 1' 'are moved in a circular path until the on the following three molds have reached the described stations, whereupon the processes are repeated. It should be noted that the invention is not limited to the arrangement shown in FIG. 3 with three molds 1, 1 ', 1' 'distributed on the turntable 21 at an angle of 120 °, but between them with a correspondingly larger turntable diameter one or more additional molds can be provided.

After leaving the casting station G, the filled mold 1 is reached before reaching the immersion station T in a demolding station (FIG. 3) opens and empties, taking the position shown in Fig. 10. The mold 1 'coming from the size bath is brought into the semi-open horizontal position shown in FIG. 13 during this movement on a circular path, while the third mold 1''is closed and pivoted vertically, after which it reaches the casting station G after it has been reached the furnace nozzle is lowered.

In order to avoid markings on the surfaces of the finished castings, which markings can be caused, for example, by the usual ejector pins, the castings are ejected according to the invention in that the opened mold is subjected to violent vibration in the demolding station. For this purpose, compressed air knockers 22 are used on clamping plates 23 (FIG. 11) to which the mold halves 1a and 1b are exchangeably fastened, for example by screws.

The demolded castings fall on a conveyor belt. 24 (Fig. 3). The conveyor belt 24 moves the castings over a cooling section in the direction of a collecting container. It can be controlled in such a way that it automatically switches on after the cast parts are ejected and transports them to the collecting container in cycles. The removal can be adapted to the existing working conditions, whereby there is not only the possibility to extend the cooling section, but by extending the conveyor belt to the To give the operator the opportunity to carry out intermediate checks on the castings by switching the direction of the conveyor belt.

In order to ensure that the cast parts on the conveyor belt 24 are accurately ejected, it may be expedient to briefly stop the circulation of the molds in the demolding station E. If you do not work with three or a multiple of three molds, but instead with four or a multiple of four molds, as shown, you can arrange the casting station, the immersion station, the preparation station and the demolding station offset by 90 ° , so that during a casting cycle the previously filled mold is automatically located in the demolding station E located between the casting station G and the immersion station T.

On the other hand, it is of course not necessary to arrange the removal station between the casting station and the immersion station halfway between the two, as shown, but rather, for example to ensure a longer solidification time after casting in the still closed mold, the demolding station E. be placed at the immersion station T.

Under these circumstances it is also possible to work with five or seven molds or a multiple thereof, as it is also conceivable, on the other hand, to use only two molds that are diametrically opposed to one another, especially if an An hold neither in the preparation station V nor in the demolding station E is required or the stopping in these stations is extremely short compared to the residence time in the casting station G.

The automatic control of the process sequence can be programmed so that the program ends when a mold has arrived in the preparation station and has to be started again by the operator, or it can run fully automatically with pre-programmed downtimes in the mentioned stations after starting until it is canceled by the operator or automatically due to a fault message.

As can be seen from the above functional description, the individual molds perform a series of opening and closing, tilting, as well as lifting and lowering movements which, controlled by electrically or electronically programmed pneumatic or hydraulic systems, the control details of which are not the subject of the present invention can be realized, for example with the aid of the following, in particular with reference to the arrangements described in FIGS. 11, 12 and 14.

As already mentioned, the two mold halves 1a and 1b are fastened to clamping plates 23, on which the compressed air knockers 22, which have also already been described, are attached. The clamping plates 23 are in turn via strips 25 with closing plates 26 connected, which are articulated with the aid of pins 27 on bearing plates 28.

Locking cylinders 29 are also arranged between these bearing plates 28 and movable in pivot bearings 30. The ends of the piston rods 31 of the locking cylinders 29 are articulated on the locking plates 26 by means of pins 32. Extending the piston rods 31 of the locking cylinders 29 causes the locking plates 26 and thus the molds 1a and 1b to pivot about the pins 27 into the open position shown in FIGS. 10 and 11, while the retraction of the piston rods swings back into the 8 results in the closed position shown. 13 shows the lower locking cylinder with the piston rod 31 retracted and the upper one with the piston rod 31 extended, and accordingly one of the molds (1a) in the closed position and the other (1b) in the open position.

Although the described pivoting device is already sufficient to open and close the molds 1, i.e. the casting, the demolding, the diving (with an additional lowering movement described later) and, apart from the tilting movement also described later, possibly also the preparation of the mold, it is particularly expedient in view of the preparation station V shown in FIGS. 13 and 14 to additionally provide a possibility by which the mold halves 1a and 1b can be moved towards and away from each other. For this purpose, the bearing plates 28 on _j are e-weils a die half 1a, 1b associated support plates 33 and 34 attached, which are interconnected by telescopic cylinders 35 provided on both sides of the locking cylinder 29, with the aid of which the plates 33 and 34 and with them the locking systems of the mold halves 1a and 1b can be approximated and removed from one another.

As already mentioned, to place the molds on the furnace nozzles 7 and to immerse them in the size bath, it is necessary to raise or lower the molds. For this purpose, the support plate 33 assigned to the mold half 1 a is connected to the upper ends of the guide bars 40 via frame parts 36, 3% and 38 and to the lower ends via angle pieces 39. The ends of the piston rods 41 of hydraulic lowering cylinders 42 also engage on the angle pieces 39, which are fastened on projecting tabs 43, which in turn are parts of guide blocks 44 for the bars 40. Extending the piston rods 41 thus causes, as shown in FIG. 10, a lowering of the angle pieces 39 and the spars 40, which are guided in the guide blocks 44 and, via the angle pieces 39 and the frame parts 36, 37 and 38, also a lowering of the Support plate 33, the mold half 1a connected to it and, via the telescopic cylinders 35, also the support plate 34 and the mold half 1b connected to it.

On the guide bushes 40 are also the journals 45 of tilting bearings provided in end shields 46 and 47, which make it possible to move the entire system described above from the vertical into FIG 13 and 14 to tilt the horizontal position shown. A swivel cylinder 48 serves this purpose, the end of which is fastened to the end shield 46 by means of a pin 49, while its piston rod 50 engages via a pin 51 on a swivel plate 52 which is rigidly connected to one of the guide blocks 44. The end shields 46 and 47 are fastened to the turntable 21 by means of screws 53.

As already indicated, the above-mentioned working cylinders are controlled by pneumatic or hydraulic systems by means of valves controlled by electrical or electronic programming.

B e z u g s z e i c h e n l i s t e

• G = casting station
• T = immersion station
• V = preparation station
• E = demolding station
• 1, 1 ', 1' '= molds
• 1a = half of 1
• 1b = half of 1
• 2 = low pressure casting furnace
• 3 = molten metal
• 4 = melting level
• 5 = cylindrical Dosing chamber
• 6 = riser pipe
• 7 = furnace nozzle
• 8 = cavities in 1
• 9 = melting channel
• 10 = coil
• 11 = Eisenjoch
• 12 = sinker
• 13 = rod
• 14 = working cylinder
• 15 = filling chamber
• 16 = connection between 5 and 15
• 17 = lowest level of 3
• 18 = work cover
• 19 = plunge pool
• 20 = immersion bath
• 21 = rotary table
• 22 = air knocker
• 23 = clamping plate
• 24 = conveyor belt
• 25 = last
• 26 = strikers
• 27 = spigot
• 28 = bearing plates
• 29 = locking cylinder
• 30 = swivel bearing
• 31 = piston rod
• 32 = pin
• 33 = support plate
• 34 = support plate
• 35 = telescopic cylinder
• 36 = frame part
• 37 = frame part
• 38 = frame part
• 39 = elbow
• 40 = guide rails
• 41 = piston rods
• 42 = lowering cylinder
• 43 = tabs of 44
• 44 = guide blocks
• 45 = journal
• 46 = end shield
• 47 = end shield
• 48 = swivel cylinder
• 49 = spigot
• 50 = piston rod
• 51 = pin
• 52 = swivel plate
• 53 = screws

Claims (10)

1. Automatically controlled low-pressure casting process, characterized by the following process steps: a) In a casting station (G), a first (1) of a number of molds (1, 1 ', 1'') arranged at regular intervals on a rotary table (21) is placed over a low-pressure casting furnace (2) known per se stands, through the riser pipe (6) filled with molten metal (3), while at the same time a second open mold (1 ') is automatically immersed in an immersion station (T) in an immersion bath (20) and lifted out of the bath again, and likewise at the same time a third partially opened mold (1 '') is prepared for the casting in a preparation station (V), for example by inserting casting cores; b) then the molds are moved on a circular path until further molds have reached the described stations (G, T, V), whereupon the processes are repeated and the filled mold (1) in each case before reaching the immersion station (T) Ent Forming station (E) automatically opens and empties, the one (1 ') coming from the immersion bath (20) is tilted into a horizontal position and the one (1'') prepared for casting is swiveled vertically and lowered onto the furnace nozzle (7) becomes. 2. The method according to claim 1, characterized in that the movement of the molds (1, 1 ', 1' ') on the circular path is interrupted when one of them is in the demolding station (E). 3. The method according to claim 1, characterized in that the opened mold is subjected to violent vibration in the demolding station (E). 4. Device for automatically carrying out the low-pressure casting method according to claims 1 to 3, characterized by a rotary table (21), on the periphery of which, at regular intervals, a number of identical or different molds (1, 1 ', 1'') with associated devices for Automatic opening and closing, tilting as well as lifting and lowering arranged and around the a casting station (G) with a known low pressure casting furnace (2), with riser pipe (6) and furnace nozzle (7), an immersion station (T) with a Immersion bath (20) and a preparation station (V) and a demolding station (E) are grouped between the casting furnace (2) and the immersion bath (20); a drive for moving the molds from station to station and a control system for pre-programmed triggering of the individual functions. 5. The device according to claim 4, characterized in that the low pressure casting furnace (2) is provided with a siphon-like filling chamber (15), the connection (16) with a metering chamber (5) below the lowest level (17) of the molten metal (3) lies. 6. The device according to claim 4, characterized in that the furnace nozzle (7) is designed as a multiple nozzle. 7. The device according to claim 4, characterized in that the immersion bath (20) consists of a size bath in a plunge pool (19) provided with an agitator. 8. The device according to claim 7, characterized in that in the immersion bath (20) a temperature control device with a heating cartridge is provided to maintain a constant temperature. 9. The device according to claim 4, characterized in that in the demolding station (E) a conveyor belt (24) is provided for the automatic removal of the castings. 10. The device according to claim 4, characterized in that the mold halves (1a, 1b) are provided with compressed air knockers (22) for marking-free demolding.

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