JP2011502051A - Ventilation unit for die casting equipment - Google Patents

Abstract

  The present invention is for a die casting apparatus having a mold cavity adapted to be filled with a liquid casting material, and a gas suction device connected to the mold cavity for extracting gas from the mold cavity by suction. The flow unit includes a flow labyrinth, and an inlet of the flow labyrinth is connected to the mold cavity, and an outlet of the flow labyrinth is connected to the gas suction device. It relates to the ventilation unit. In order to improve the ventilation unit so that the exhaust of the mold cavity can be improved without risking that liquid casting material may escape from the ventilation unit, according to the present invention, the flow labyrinth of the flow labyrinth is improved. It is proposed that the flow cross section is variable. Furthermore, a die casting apparatus provided with this kind of ventilation unit is proposed.

Description

  The present invention is for a die casting apparatus having a mold cavity adapted to be filled with a liquid casting material, and a gas suction device connected to the mold cavity for extracting gas from the mold cavity by suction. The flow unit includes a flow labyrinth, the flow labyrinth inlet is adapted to be connected to the mold cavity, and the flow labyrinth outlet is connected to the gas suction device. Relates to a ventilation unit adapted to

  The invention also relates to a die-casting device provided with this type of ventilation unit.

  For example, a die casting apparatus is known from DE 20 2005 019288 U1. These die casting devices have a mold cavity into which a liquid casting material such as molten aluminum or magnesium can be injected. By means of a gas suction device, the bubbles are trapped in the casting material (initially liquid and then cured in a very short time), to avoid the trapped bubbles from degrading the quality of the castings that are sometimes produced. Air can be extracted from the mold cavity. Extraction of air from the mold cavity can be performed before and during filling of the mold cavity. In order to avoid liquid casting material escaping from the mold cavity and reaching the gas suction device or a vent valve located upstream of the gas suction device, between the mold cavity and the gas suction device, A ventilation unit forming a flow labyrinth is arranged, the flow labyrinth inlet is adapted to be connected to the mold cavity and the flow labyrinth outlet is adapted to be connected to a gas suction device. For example, the inlet can be connected to the mold cavity via a vent channel and the outlet of the flow labyrinth can be connected to a gas suction device via a suction line. Flow labyrinth can be used to extract gas from the mold cavity. As the liquid casting material enters the flow labyrinth, it solidifies inside the flow labyrinth, thus interrupting the flow connection between the mold cavity and the gas suction device. This type of ventilation unit can be used to extract gas from the mold cavity, and the casting material that penetrates into the flow labyrinth of the ventilation unit solidifies, but is also referred to as a chill block system or corrugated plate.

  The main task of the gas suction device of the die casting apparatus is to exhaust a certain amount of air from the mold cavity in a short time, ie in a few seconds. In this case, air is drawn from the mold cavity through a relatively narrow gap. Narrow gaps impair extraction ability. In many cases, it has been found that even with a powerful gas suction device, exhaust from the mold cavity is insufficient.

EP 0 930 114 A1 EP 0 878 255 A2 & A3 JP 04 013464 A EP 1 074 321 A1 JP 61 038769 A EP 0 342 872 A2 DE 20 2005 019 288 U1 DE 102 52 183 B4 DE 37 87 507 T2 & EP 0 268 113 A2

  The object of the present invention is to develop a vent unit of the type mentioned at the outset so that an improvement in the exhaust of the mold cavity is possible without risking that liquid casting material can escape from the vent unit. That is.

  This object is achieved according to the invention in that, in the case of a ventilation unit of the kind mentioned at the outset, the flow cross section of the flow labyrinth is variable. This provides the possibility of reducing flow losses inside the flow labyrinth when gas is extracted from the mold cavity. This is because a relatively large flow cross section can be selected for the flow labyrinth to extract gas from the mold cavity. As a result, the exhaust of the mold cavity can be significantly improved. On the other hand, in order to avoid that the liquid casting material can flow through the flow labyrinth and escape from the ventilation unit, the flow cross section of the flow labyrinth can be reduced, so that the casting material flowing in is surely inside the flow labyrinth. It is guaranteed to solidify.

  Advantageously, the liquid casting material flowing into the flow labyrinth is adapted to change the flow cross section of the flow labyrinth. This gives the possibility of choosing a relatively large flow cross section at the beginning of the casting operation in order to be able to extract gas effectively from the mold cavity. The extraction operation can be continued until the casting material filled in the mold cavity enters the flow labyrinth. At that time, for example, the inflowing casting material collides with a wall portion of the flow labyrinth with a strong force, so that the inflowing casting material can reduce the flow cross section of the flow labyrinth. At that time, the flow cross-section can be reduced by utilizing the fact that the casting material that flows in impinges and collides with the portion of the wall.

  For example, the flow labyrinth has first and second protrusions, and the first and second protrusions are opposed to each other and are offset with respect to each other in the flow direction, and between the first and second protrusions. It can be realized that the interval is variable. In any case, the flowing casting material is changed in direction by the first and second protrusions, and a considerable amount of momentum is transmitted to the protrusions, so that the first and / or second protrusions are relative to each other. As a result, the flow cross section of the flow labyrinth is reduced.

  The first protrusion is preferably adapted to be offset with respect to the second protrusion in the flow direction. Therefore, the first protrusion is held in a movable manner, whereas the second protrusion is formed in a fixed manner. When the incoming casting material collides with the first projection, the first projection changes position with respect to the second projection, thereby reducing the flow cross section of the flow labyrinth.

  When the ventilation unit according to the present invention is structurally particularly simple, the first protrusion is held on a movable base. The platform can take the form of, for example, a displaceable sliding part, the sliding part having a first end position where the flow labyrinth has a relatively large flow section and a flow section where the flow labyrinth is relatively small. It is movable back and forth between the second end position. The sliding part is preferably held on a linear guide, which can be formed as a dovetail-shaped guide, for example.

  As already explained, it is advantageous if the first projection is adapted to be displaced by a liquid casting material flowing into the flow labyrinth. For example, the first protrusion can be displaced by the liquid casting material, and as a result, the flow cross section of the flow labyrinth can be reduced.

  It is advantageous if the first protrusion is adapted to shift against an elastic restoring force. As a result, the first protrusion is shifted from a stop position taken as long as the liquid casting material does not collide with the first protrusion to an operation position in which the flow labyrinth has a reduced flow cross section compared to the stop position. Can do. The transition from the stop position to the action position is performed against the action of the elastic restoring force. When the casting material no longer collides with the first protrusion, the first protrusion automatically returns to its stop position due to the restoring force acting on the first protrusion.

  It is particularly advantageous if the first projection is adapted to be constrained at the operating position of the first projection. This has been found to facilitate the removal of the solidified casting material from the flow labyrinth. This is because constraining the first protrusion means that the solidified casting material is not subjected to any force by the elastically stressed first protrusion.

  Normally, liquid casting material is injected into the mold cavity by an injection piston, after which the liquid casting material fills the mold cavity as completely as possible and then flows at a very high speed to the inlet of the flow labyrinth. In order to avoid damaging the movable first projection by the casting material flowing into the flow labyrinth at a high speed, the liquid casting material first collides with the stationary projection, and only after that the movable projection becomes the movable projection. It is advantageous if they collide and are turned at each of the protrusions. Therefore, the casting material that flows in first collides with the fixed projection and changes direction with the fixed projection, thereby transmitting a considerable momentum to the fixed projection. When the liquid casting material further flows into the flow labyrinth, the liquid casting material collides with the movable protrusion at a reduced speed and is re-oriented by the movable protrusion. At the same time, the movable protrusion is This reduces the flow cross section of the flow labyrinth while deviating with respect to the fixed projection. Subsequently, the liquid casting material, which is clearly decelerated at that time, can collide with further fixed projections, the liquid casting material is redirected again with further fixed projections and subsequently movable. It collides again with the protrusion. This process can be repeated over and over, and the casting material changes direction at each of the movable protrusions, so that the movable protrusions move further because the momentum is transmitted, and hence the flow labyrinth. This further reduces the flow cross section.

  Inside the flow labyrinth, the intruding casting material cools down and eventually solidifies. Accordingly, the flow labyrinth is advantageously formed of a material that conducts heat as much as possible, as a result of which particularly effective heat removal can be ensured.

  In a particularly preferred configuration of the ventilation unit according to the invention, the ventilation unit comprises a ventilation block comprising first and second block parts, the first block part being on the first die half of the die casting apparatus. The second block portion can be fixed on the second die half of the die casting apparatus, the two block portions form a flow channel between the block portions, and the first block portion A first protrusion disposed on the block portion and a second protrusion disposed on the second block portion protrude into the flow channel to form a flow labyrinth, and the first protrusion and / or the second protrusion Protrusions are movably held on the first and second block parts, respectively. The mold cavity of the die casting apparatus is usually formed by two die halves, the first die half is held movable, and the second die half is held fixed, completing the casting operation. Later, by moving the first die half away from the second die half, the manufactured casting can be easily removed from the mold cavity. The ventilation unit forms a ventilation block having two block portions. In this case, the first block portion can be disposed on the movable die half portion, and the second block portion can be disposed on the fixed die half portion. By opening, the flow labyrinth arranged between the two block portions can also be opened. The flow labyrinth is formed by the protrusions disposed on the respective block portions, and the first and / or second protrusions are used to change the flow cross section of the flow labyrinth. Above, it is held movable.

  In an advantageous embodiment of the invention, the first and / or second protrusions are movably mounted on the first or second block part or in the first or second block part, respectively. Fixed on the board. The holding plate may take the form of a sliding portion that is detachably mounted on or in each block portion by, for example, a linear guide portion.

  It is advantageous if the holding plate can be displaced against the action of the elastic restoring force. Since the elastic restoring force acts on the holding plate, the holding plate automatically assumes the first end position as long as the liquid casting material has not yet entered the flow labyrinth. When the liquid casting material enters, the holding plate can be displaced from the first end position, which reduces the flow cross section of the flow labyrinth.

  Preferably, at least one end position of the holding plate is adjustable. For this purpose, adjustment elements, such as adjustment screws, can be used. This adjustment element forms a stop for the holding plate against which the holding plate is pressed so long as casting material has not yet entered the flow labyrinth, since the elastic restoring force acts on the holding plate.

  Advantageously, the position of the first and / or second protrusion can be sensed by a measuring sensor. This allows the measurement records of the manufactured castings that can obtain the position of the first and / or second protrusions during the manufacture of the castings to be always prepared, Improved monitoring and verification of casting operations.

  For example, an electrical signal transmitter can be used as the measurement sensor, and in particular, it can be realized that the position of the first and / or second protrusion can be sensed by a position encoder. The signal transmitter can be connected to the control unit of the die casting apparatus via a signal line.

  Advantageously, the holding plate on which the first or second protrusion is held can be restrained. This makes it easier to open the flow labyrinth and remove the cast material solidified within the flow labyrinth.

  As explained at the outset, the present invention relates not only to the above-mentioned type of ventilation unit, but also to a die casting apparatus comprising this type of ventilation unit. The die casting apparatus includes a mold cavity adapted to be filled with a liquid casting material, and a gas suction device connected to the mold cavity, wherein the venting unit includes the mold cavity and the gas suction device. Connected between. The mold cavity can be connected to the inlet of the flow labyrinth of the ventilation unit via the ventilation channel of the die casting device, and the outlet of the flow labyrinth can be connected to the gas suction device via a suction line. it can. In this case, it is advantageous if a suction valve is connected in the suction line.

  For a more detailed description, a preferred embodiment of the present invention is described below in conjunction with the drawings.

1 is a schematic view of a die casting apparatus according to the present invention comprising a ventilation unit according to the present invention. The enlarged view in the 1st end position of the ventilation unit of FIG. 1 provided with the movable protrusion. The enlarged view in the 2nd end position of the ventilation unit of FIG. 1 provided with the movable protrusion.

  FIG. 1 schematically shows a die casting apparatus 10 according to the present invention. The die casting apparatus 10 has a movable first die half 11 and a fixed second die half 12, and a first die. The half 11 and the second die half 12 interact in a customary manner with a clamping unit which is known per se and which is not shown in the drawing. The mold clamping unit includes a movable platen and a fixed platen. Although the movable platen and the fixed platen are not shown in the drawings for improving the appearance, two die halves 11 are provided on each of the movable platen and the fixed platen. , 12 is held in a known manner. A clamping force that can be determined in advance can be exerted on the two die halves 11 and 12 by the clamping unit. The two die halves 11, 12 form a mold cavity 14 between them, the mold cavity 14 having the form of a casting to be cast, in which the casting material, eg a melt, preferably a liquid, is formed. Aluminum material or liquid magnesium material can be injected. For this purpose, the mold cavity 14 has an inlet opening, which is commonly referred to as a “gate” and is provided with the reference numeral 15 in FIG. The gate 15 is connected to the casting chamber 18 via the inlet channel 17. The casting chamber 18 has a filling opening 19, and an injection piston 21 is mounted in the casting chamber 18 so as to be displaceable.

  The injection piston 21 is held on a piston rod 22, and the end of the piston rod 22 that is remote from the injection piston 21 is fixed on the operation piston 24. The operation piston 24 is detachably mounted in an operation cylinder 26 of a drive unit provided with a reference numeral 27 as a whole. The drive unit 27 has a pressure cylinder 29. The pressure cylinder 29 is hydraulically coupled to the operation cylinder 26, and a pressure piston 30 is mounted in the pressure cylinder 29 so as to be displaceable. The pressure piston 30 has a thrust pin 31 on its end surface facing the operation cylinder 26, and the thrust pin 31 enters the operation cylinder 26 on the side of the operation cylinder 26 away from the piston rod 22.

  The pressure cylinder 29 receives hydraulic oil to be pressurized and is connected to a pressure accumulator (not shown in the drawing) via a pressure line 33 because it is known per se. An electrically controllable control valve 34 in the form of a solenoid is inserted into the pressure line 33 and uses the control valve 34 to flow between the accumulator (not shown in the drawing) and the pressure cylinder 29. The connection can be opened and closed in a defined manner.

  Since the operating cylinder 26 is flow-connected to the hydraulic oil storage tank 37 via the outlet line 36, the hydraulic oil can be sent from the operating cylinder 26 to the storage tank 37 via the outlet line 36.

  The piston rod 22 carries a bush 39 almost in the middle along the piston rod in the longitudinal direction, and a carrying arm 40 is fixed on the bush. The carrying arm 40 carries a ruler 41 at the end, and the ruler 41 Interacts with the position encoder 42.

  The position encoder 42 is connected to the electric control unit 46 via the signal line 44, and the control valve 34 is also connected to the electric control unit 46 via the control line 48.

  The die casting device 10 has a gas suction device 50, which is known per se and is only schematically represented in the drawing, but via a mold cavity 14 and a vent channel 52 extending from the mold cavity 14. A ventilation unit 55 is adjacent to the ventilation channel 52, and a suction line 57 is adjacent to the ventilation unit. An outlet valve 59 is connected in the suction line 57, but the outlet valve 59 is configured as a solenoid and is inserted into the control unit 46 via the control line 60.

  2 and 3 show the ventilation unit 55 in an enlarged manner. The ventilation unit 55 forms a ventilation block 62 including a first block part 63 and a second block part 64, and the first block part 63 is fixed on the movable die half part 11, and the second block part 64 is Fixed on a fixed die half 12. The two block parts 63 and 64 form a flow channel 66 therebetween, which is adjacent to the ventilation channel 52 and connected to the suction line 57 via an outlet channel 67 passing through the second block part 64. Is done. A rib-shaped first protrusion 69 and a rib-shaped second protrusion 70 protrude in the flow channel 66, and the first protrusion 69 and the second protrusion 70 are opposed to each other in the flow direction. The flow labyrinths 72 are formed between the first protrusions 69 and the second protrusions 70, which are arranged in a shifted manner and are inserted into each other in a comb-like manner.

  Since the first protrusion 69 is known per se, it is fixed on the holding plate 74 by a screw connection not shown in the drawing in order to improve the appearance, and the holding plate 74 is formed in the manner of a sliding part and is linear. The guide portion 75, for example, a dovetail-shaped guide portion, is detachably mounted in the concave portion 77 of the first block portion 63. A compression spring 80 having an elastic restoring force acts on the holding plate 74 via a thrust rod 79. The compression spring 80 is disposed in the spring housing 82, and the spring housing 82 is fixed to the side away from the movable die half 11 outside the first block portion 63. 79 passes, the free end of the thrust bar carries an extension arm 83, which interacts with the electrical position encoder 85 and switches in contact at the first end position of the holding plate 74 shown in FIG. It contacts the part 86. The position encoder 85 and the switching contact 86 are connected to the control unit 46 via respective signal lines 87 and 88, which are only partly shown in the drawing in order to improve the appearance.

  A restraint mechanism 90 is disposed between the spring housing 82 and the extension arm 83, and the thrust rod 79 passes through the restraint mechanism 90. Since the restraining mechanism 90 is known per se and has restraining means, for example tension means, in a manner not shown in the drawings, the thrust rod 79 and thereby the holding plate 74 and the first projection 79 are also restrained. Means can be used to constrain at any desired position.

  A compression spring 80 having a spring force in the direction of the movable die half 11 acts on the holding plate 74. In the position shown in FIG. 2, the holding plate 74 is at an end face 92 remote from the thrust rod 79 and abuts an adjustable stop in the form of an adjusting screw 93, which adjusts the position of the holding plate 74. Therefore, the position of the first protrusion 69 is also determined in advance.

  The temperature measurement sensor 95 enters the first block part 63. The temperature measurement sensor 95 is connected to the control unit 46 via the signal line 96.

  The second protrusions 70 are fixed on the second block portion 64 in an immobile state, but it is also possible to use a screw connection not shown in the drawing since it is known per se for fixing these protrusions. Is possible.

  Therefore, the holding plate 74 can also be displaced back and forth between the first end position shown in FIG. 2 and the second end position shown in FIG. 3. Here, at the first end position, the holding plate 74 comes into contact with the adjustment screw 93 at its end face 92, and the end face 92 is spaced from the adjustment screw 93 at the second end position. At the first end position, the first protrusion 69 takes a relatively large distance from the second protrusion 70, so that the flow labyrinth 72 has a relatively large flow cross section. The flow cross section of the flow labyrinth 72 decreases as the displacement of the holding plate 74 to the second end position increases. This is particularly evident from FIG.

  In order to produce a casting, molten metal is injected into the mold cavity 14 by the injection piston 21. At the beginning of the casting operation, the injection piston 21 assumes a retracted position that exposes the filling opening 19, so that the casting chamber 18 can be filled with molten metal. Subsequently, the injection piston 21 is pushed into the casting chamber 18 by the drive unit 27. The path along which the injection piston 21 travels can be sensed by the position encoder 42. Initially, the liquid casting material is transported to the gate 15 by the injection piston 21 and at the same time air and casting gas are passed from the mold cavity 14 by the gas suction device 50 through the vent channel 52, flow labyrinth 72, outlet channel 67, and suction line 57. And the outlet valve 59 is opened.

  Once the injection piston 21 reaches the position where the molten metal has reached the gate 15 according to the signal of the position encoder 42, the injection piston 21 is further pushed into the casting chamber 18 at a high speed in a very short time, and the mold is exhausted in advance. The drive unit 27 is actuated by the control unit 46 via the control valve 34 so that the cavity 14 is completely filled with liquid casting material. The liquid casting material 100 finally reaches the inlet 98 of the flow labyrinth 72, first turned by the second protrusion 70, and then hits the first protrusion 69. This is represented in FIG. As a result, the liquid casting material 100 collides with the first protrusion 69 at a very high speed, and as a result, a considerable momentum is transmitted to the first protrusion. As a result, the first protrusion 69 is displaced in the direction away from the adjusting screw 93 against the action of the compression spring 80 together with the holding plate 74, so that the flow labyrinth 72 extracted from the mold cavity 14 via the gas is The result is a reduction in the flow cross-section that was initially significant. The liquid casting material 100 being continuously turned inside the flow labyrinth 72 has the effect of slowing the casting material 100. At the same time, heat from the liquid casting material 100 is dissipated to the block parts 63 and 64, to the projections 69 and 70, and to the holding plate 74, so that the temperature of the casting material 100 is greatly reduced and the casting material is finally reduced. The casting material 100 solidifies inside the flow labyrinth 72 before reaching the outlet 99 of the flow labyrinth 72.

  The casting material 100 that hardens in the mold cavity 14 can be subjected to very high pressure by the injection piston 21, and the casting material 100 is secondarily compressed.

  Once the casting operation has been carried out, the first block part 63 fixed on the movable die half 11 is brought together with the movable die half 11 to a distance from the second block part 64. Therefore, the mold cavity 14 can be opened by displacing the movable die half 11, and the flow labyrinth 72 can be opened simultaneously. Therefore, the casting material 100 cured inside the flow labyrinth 72 can be easily removed from the flow labyrinth 72. To make removal easier, the retaining plate 74 together with the first protrusion 69 is represented in FIG. 2 so that the cast material 100 cured in the flow labyrinth 72 is not subjected to any force by the first protrusion 79. What is necessary is just to restrain by the restraint mechanism 90 in the 2nd end position.

  After removing the solidified casting material 100 from the flow labyrinth 72 and removing the casting from the mold cavity 14, the first block 63 together with the movable die half 11 either in the direction of the second block 64 or Since it can be moved again in the direction of the fixed die half 12, a new casting operation can then be carried out.

  Due to the movable platform of the first protrusion 69, the flow labyrinth 72 can have a considerable flow cross section at the beginning of the casting operation, so that the mold cavity 14 can be reliably evacuated by the gas suction device 50. On the other hand, in order to avoid that the liquid casting material 100 can flow through the flow labyrinth 72 during the casting operation, the flow cross-section is reduced because of the movable base of the first protrusion 69, and the first protrusion 69 is reduced to the flow labyrinth. It can be displaced by the casting material 100 entering the 72. This eliminates the need for electrical, hydraulic or pneumatic control of the movement of the first protrusion 69.

Claims (15)

A vent unit for a die casting apparatus, comprising: a mold cavity adapted to be filled with a liquid casting material; and a gas suction device connected to the mold cavity for extracting gas from the mold cavity by suction. There,
The vent unit includes a flow labyrinth, the flow labyrinth inlet is adapted to be connected to the mold cavity, and the flow labyrinth outlet is adapted to be connected to the gas suction device. In the ventilation unit,
The ventilation unit, wherein the flow cross section of the flow labyrinth (72) is variable.   Ventilation unit according to claim 1, characterized in that the flow cross section of the flow labyrinth (72) is adapted to be changed by the liquid casting material flowing into the flow labyrinth (72). unit.   3. A ventilation unit according to claim 1 or 2, wherein the flow labyrinth (72) has first and second projections (69, 70) which are opposed to each other and are offset relative to each other in the flow direction. The ventilation unit is characterized in that the interval between the protrusions is variable.   A ventilation unit according to claim 3, characterized in that the first projection (69) is adapted to be offset with respect to the second projection (70) in the flow direction.   The ventilation unit according to claim 3 or 4, wherein the first protrusion (69) is held on the movable base (74).   6. A ventilation unit according to claim 3, 4 or 5, characterized in that the first projection (69) is adapted to be displaced by a liquid casting material flowing into the flow labyrinth.   The ventilation unit according to any one of claims 3 to 6, wherein the first protrusion (69) is adapted to be displaced against an elastic restoring force. .   The ventilation unit according to any one of claims 3 to 7, wherein the first protrusion (69) is formed in the second protrusion (70) in the flow direction of the liquid casting material flowing into the flow labyrinth (72). A ventilation unit characterized by being arranged rearward.   The ventilation unit according to any one of claims 1 to 8, wherein the ventilation unit (55) includes a ventilation block (62) including first and second block portions (63, 64), The first block part (63) is fixable on the first die half (11) of the die casting apparatus (10), and the second block part (64) is a second die of the die casting apparatus (10). Can be fixed on the half (12), and the two block parts (63, 64) form a flow channel (66) between the block parts and are arranged on the first block part (63). A first protrusion (69) and a second protrusion (70) disposed on the second block portion (64) protrude into the flow channel (66), and the first protrusion (69) and / or The second protrusions (70) are respectively connected to the first and second bushes. Click portions (63, 64) on being held movably in a ventilation unit according to claim.   10. A ventilation unit according to claim 9, wherein the first and / or second protrusions (69, 70) are on the first or second block (63, 64) or the first or second. A ventilation unit characterized by being fixed on a holding plate (74) movably mounted in each of the two block parts (63, 64).   The ventilation unit according to claim 10, wherein the holding plate (74) is displaceable against the action of an elastic restoring force.   The ventilation unit according to claim 10 or 11, wherein at least one end position of the holding plate is adjustable.   The ventilation unit according to any one of claims 9 to 12, wherein the position of the first and / or second protrusion (69 or 70) can be sensed by a measurement sensor (85). unit.   The ventilation unit according to any one of claims 10 to 13, wherein the holding plate (74) can be restrained.   A mold cavity (14) adapted to be filled with a liquid casting material, and a gas suction device connected to the mold cavity (14) for extracting gas from the mold cavity (14) by suction. 50) and a ventilation unit (55) according to any one of claims 1 to 14, wherein the ventilation unit is connected between the mold cavity (14) and the gas suction device (50). 55).

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