DE102019107325A1 - Melting unit for a molding machine and molding machine with such - Google Patents

Abstract

Melting unit for a molding machine, with - a melting chamber (4), the melting device (1) being designed to melt a material to be arranged in the melting chamber (4), - a discharge device (8), which discharge device (8) is designed to to bring out a melted material from the melting chamber (4), and an evacuation device (12) and / or protective gas flooding device, which is designed to subject at least the melting chamber (4) to a negative pressure, the melting chamber (4) on its inner wall and / or the discharge device (8) has at least one recess on an outer surface, so that between the inner wall of the melting chamber (4) and the outer surface of the discharge device (8) in at least one position of the discharge device (8) relative to the melting chamber (4) there is a fluid connection for evacuating the Melting chamber (4) and / or for flooding the melting chamber (4) with a protective gas through the evacuation ngsvorrichtung (12) and / or protective gas flooding device.

Description

The present invention relates to a melting unit for a shaping machine with the features of the preamble of claim 1, and to a shaping machine with such a melting unit.

Shaping machines can be understood to mean die casting machines, transfer presses, injection molding machines or the like. The state of the art is presented below using a die-casting machine. The same applies to general molding machines.

Die-casting machines known from the prior art generally have a melting chamber, the melting unit being designed to melt a material to be arranged in the melting chamber. This material to be melted (can also be regarded as raw material) can be provided in the form of bars, which are also referred to as ingot (ingot) and can be fed to the melting chamber via a pick-and-place handling system. Such an ingot already has the precisely dosed mass of material to be processed during a cycle.

The inductive heating of the material to be melted in the melting chamber can be done by an induction coil assigned to the melting unit, which is at least partially arranged around the melting chamber. The ingot (also called raw material or material to be melted in the following) can thus be melted by induction.

In order to prevent the melted material from reacting with the ambient air - more precisely with the oxygen contained in the ambient air - it can be provided that the melting chamber is evacuated during the cycle and / or is flooded with a protective gas.
Consequently, the die-casting machines known in the prior art have an evacuation device, which evacuation device is designed to apply a negative pressure to at least the melting chamber. It can be provided that for such a purpose the die casting machine has a vacuum pump for sucking the ambient air out of the melting chamber.

In addition, it can be provided that the melting chamber is flooded with a protective gas or completely flushed with protective gas. This provision of a protective gas in the melting chamber during melting also prevents the melted material from reacting with the ambient air (and the oxygen contained in the ambient air).

Furthermore, die casting machines known from the prior art have a discharge device which is designed to discharge a melted material from the melting chamber. With such a discharge device, it can be provided that the melted material is pushed out of the melting chamber, for example, and is introduced into a cavity of a molding tool.

Since the evacuation of the melting chamber and / or the flooding of the melting chamber with a protective gas is an essential part of the cycle in the die-casting machine, this evacuation and / or flooding process of the evacuation device and / or protective gas flooding device also takes up a substantial proportion of the time of the cycle. However, since production is always about the number of pieces to be produced per unit of time, it is important to reduce cycle times.

For example, it is from the WO 2011/035765 A1 It is known to establish flow connections in the injection piston - more precisely the associated piston rod of the injection piston - which represent an increased flow cross-section between an annular gap and an evacuation device, so that a longer evacuation time can be achieved.

However, it is disadvantageous that the annular gap shows a cutting cross-sectional tapering, which allows a shortened cycle time.

The object of the invention is to provide a melting unit for a shaping machine and a shaping machine with such a melting unit which allows a more rapid evacuation of a melting chamber and / or flooding of a melting chamber with a protective gas.

This object is achieved by a melting unit with the features of claim 1.

This is done in that the melting chamber has at least one recess on its inner wall and / or the discharge device has at least one recess on an outer surface, so that a fluid connection for evacuating the melting chamber and / or between the inner wall of the melting chamber and the outer surface of the discharge device in at least one position of the discharge device relative to the melting chamber for flooding the melting chamber with a protective gas through the evacuation device and / or protective gas flooding device.

By providing at least one such recess, an enlarged flow cross section can be provided for the medium to be evacuated and / or flooded, whereby the melting chamber can be evacuated and / or flooded at an increased speed and the cycle time of the molding machine can be significantly reduced.

Advantageous embodiments of the invention are defined in the dependent claims.
The melting chamber can be evacuated and / or flooded through an annular gap. This annular gap is formed by the dispensing device (which in most exemplary embodiments is formed by the injection piston) and the surrounding wall of the dispensing device. However, there is an endeavor to keep this annular gap as small as possible, since it is important in the subsequent process cycle to maintain the negative pressure, whereby this annular gap must be sealed.

It is preferably provided that the at least one recess enlarges an annular gap fluid connection for evacuating the melting chamber and / or flooding the melting chamber with a protective gas through the evacuation device and / or protective gas flooding device, which is formed by an annular gap between the inner wall of the melting chamber and the outer surface of the discharge device.

In other words, it can thus be provided that the annular gap is supplemented by at least one recess according to the invention, whereby the cross-section for evacuation and / or flooding is significantly increased in at least one position of the dispensing device.

It can be provided that several recesses are provided on the inner wall of the melting chamber and / or the outer surface of the discharge device. The sum of the recesses and the size of the recesses can depend, for example, on a maximum output of the evacuation device and / or protective gas flooding device.

It can particularly preferably be provided that the at least one recess is formed by a groove.

It can be provided that the at least one recess is formed by at least one bore. This at least one bore can be provided in the discharge device or in the wall surrounding the discharge device in order to provide a fluid connection for evacuating the melting chamber and / or for flooding the melting chamber with a protective gas through the evacuation device and / or the protective gas flooding device. In other words, a bypass bore can be provided through the at least one bore in at least one position of the dispensing device.

Grooves, bores and other types of recesses can of course be combined.

It is preferably provided that the at least one recess only releases the fluid connection for evacuating and / or flooding the melting chamber in a retracted position of the discharge device from the melting chamber.

Since the at least one recess releases the fluid connection for evacuation and / or flooding in a retracted position of the discharge device from the melting chamber, the essential advantage can be created that this "additional" at least one recess - for example in addition to the annular gap - is only released in one position and this position is only taken when the melting chamber is evacuated and / or flooded. In the remaining positions (for example a melting position or a discharge position) of the discharge device, this at least one recess is not released, which means that the at least one recess does not have to be sealed (to maintain a negative pressure) or even with an inadequate seal the melting chamber by a flowing fluid (for example ambient air) is slowed down.

It can be provided that the melting unit has an induction coil which surrounds the melting chamber at least in some areas for inductive melting of a material to be arranged in the melting chamber. It can be provided that a separating agent can be applied to an inside of the melting chamber, with the separating agent being able to prevent a chemical reaction between the melted material and a material of the melting chamber.

It is preferably provided that the discharge device has an injection piston which is designed to push the melted material out via a discharge opening in the melting chamber.

In a preferred embodiment of the invention it can be provided that the melting chamber is made of a non-metallic material - preferably graphite, stone, ceramic, a ceramic alloy or a glass.

It can preferably be provided that the melting chamber has a cylindrical, in particular circular cylindrical, inner wall.

Accordingly, it can also or alternatively be provided that the dispensing device - preferably an injection piston - has a cylindrical, in particular circular cylindrical, outer surface.

Both the inner wall and the outer surface can have further structures in addition to the cylindrical basic shape. For example, the inner wall can have a recess for introducing the ingot and seals or the like can be attached to the outer surface.

It can be provided that the discharge device is arranged concentrically in the melting chamber.

Furthermore, protection is sought for a molding machine, preferably a vacuum pressure casting machine, with a melting unit according to the invention, whereby it can preferably be provided that a cavity is provided, whereby melted material from the melting chamber can be introduced into the cavity for a molding process by the discharge device.

• 1a ein Ausführungsbeispiel einer erfindungsgemäßen Aufschmelzeinheit,
• 1b einen Schnitt durch die Aufschmelzeinheit der 1a,
• 2 eine Detailansicht einer Eindüsvorrichtung,
• 3a eine Detailansicht der Evakuierungsvorrichtung,
• 3b die in 3a gekennzeichnete Schnittdarstellung,
• 3c eine alternative Evakuierungsvorrichtung zu 3a und
• 4 eine Detailansicht einer Dichtung

Further advantages and details of the invention emerge from the figures and the associated description of the figures. Show:

• 1a an embodiment of a melting unit according to the invention,
• 1b a section through the melting unit of 1a ,
• 2 a detailed view of an injection device,
• 3a a detailed view of the evacuation device,
• 3b in the 3a marked sectional view,
• 3c an alternative evacuation device 3a and
• 4th a detailed view of a seal

1a shows an embodiment of a shaping machine in the area of a melting device 1 . This In 1a Melting unit shown 1 has a bearing housing 3 on, the bearing housing 3 with cooling fins 2 Is provided. These cooling fins 2 allow an effective dissipation of heat, which in use of the melting unit 1 is produced.

By providing cooling fins 2 a bearing housing 3 can be an existing cooling system of a melting unit 1 be supplemented or improved. It can even be provided that through the cooling fins 2 individual or even all fluid cooling circuits (as known from the prior art) which work with a fluid cooling medium can be dispensed with. It is also quite conceivable that the cooling fins 2 the melting unit 1 Equip with additional fans or fans to increase the efficiency of heat dissipation through the cooling fins 2 to increase.

1b shows a section through the melting unit of FIG 1a so that the individual components of the melting unit 1 are easier to see. These are to be explained in more detail below using a generally described process flow.

In a first step of the melting unit 1 becomes the melting unit 1 a material to be melted (also called ingot 5 called) supplied. This loading with the ingot 5 in the present exemplary embodiment via a pick-and-place handling system for the melting chamber 4th via the discharge opening 9 supplied, this discharge opening 9 on a side of the melting unit facing the cavity 1 is located.

The ingot 5 is in the melting chamber 4th in the effective range of an induction coil 6th filed. The injection piston is used for this 7th moved to a storage reference position and serves as a mechanical stop or additional positioning aid for the loading system. After placing the ingot 5 in the melting chamber 4th the loading system extends again.

The next step is the melting chamber 4th in which the ingot 5 located, evacuated and / or flooded with a protective gas, so that the ingot 5 During the subsequent melting, more precisely the melted material, does not react with the ambient air (more precisely with the oxygen in the ambient air), which would result in impurities (for example through the reaction of iron-containing melted material with oxygen to form iron carbide).

In order to generate a large flow cross-section, so that when the melting chamber is evacuated 4th A negative pressure can be generated in a short time are recesses (here as grooves 15th designed) provided.

In addition, air or gas is passed through an annular gap 17th (Annular gap fluid connection) between injection piston 7th and the melting chamber 4th from the melting chamber 4th discharged. The However, thanks to a large flow cross-section, recesses allow much faster evacuation than just an annular gap 17th .

Alternatively or in addition, a feed device can be provided which the melting chamber 4th floods with a protective gas.

Around the melting chamber 4th to be sealed against the environment are in a rear area of the injection piston 7th two seals 11 provided which the piston rod 13 of the injection piston 7th opposite the bearing housing 3 seal (in relation to these seals 11 is on the 4th referenced, which shows a detailed view).

After introducing a protective gas and / or evacuating the melting chamber 4th becomes the ingot 5 via the induction coil 6th inductively heated and melted.

After the ingot 5 melted, the injection piston 7th by means of a linear drive, not shown, linearly in the direction of the discharge opening 9 moves, removing the melted material from the melting chamber 4th is pushed out and optionally injected into a cavity of the molding machine (not shown for reasons of clarity).

After the molten material has been discharged from the melting chamber 4th a finished workpiece can be removed from the cavity of a molding tool of the molding machine and the injection piston 7th is driven back.

Because the injection piston 7th however not always all of the melted material from the melting chamber 4th to be applied (sometimes due to the annular gap 17th ), becomes the injection piston 7th Brought into a (retracted) blow-out position, creating an opening 10 the melting chamber 4th is released.

The injection device 14th it is thus made possible to introduce a medium (in this exemplary embodiment compressed air) into the melting chamber 4th over the opening 10 blown in and thus residues of the melted material from the melting chamber 4th via the discharge opening 9 blow out.

After the blowout is complete, the injection piston can 7th can be moved back into a storage reference position (as shown by FIG. 1b) and the cycle can begin again.

2 shows a detailed view of the injection device 14th It is easy to see how the injection piston 7th by means of its piston rod 13 is placed in a retracted position so that an opening 10 the melting chamber 4th is released. The melting chamber 4th is thereby through the inner wall of the melting cylinder 16 educated.

About residues from the melting chamber 4th can be blown out by the injection device 14th a medium in the melting chamber 4th blow in, removing residue from the melting chamber 4th via the discharge opening 9 from the melting chamber 4th be blown out.

These residues are characterized by high surface hardness and sharp burrs or edges. By moving these residues with the injection piston 7th there is increased wear between the injection piston 7th and the inner wall of the melting cylinder 16 when these residues from the melting chamber 4th cannot be removed. As a result, the service life of the melting unit suffers 1 drastically below.

Because the residue in the melting chamber 4th do not adhere, they can be injected using an injection device 14th easily removed and thus blown out. For this reason, a single compressed air nozzle can be provided directly on the melting chamber 4th on the bearing housing 3 that blows in compressed air are sufficient. Of course, several compressed air nozzles can also be used.

3a shows a detailed view of the evacuation device 12th in the area of the suction opening 18th through which the evacuation device 12th builds up a negative pressure.

3b shows the in 3a marked sectional view AA.

When a negative pressure builds up in the melting chamber 4th (and / or when flooding the melting chamber 4th with a protective gas) is over the recess (which as a groove 15th is formed) and the ring channel 17th , which is between the injection piston 7th and the inner wall of the melting cylinder 16 trains ambient air from the melting chamber 4th discharged and / or the melting chamber 4th a protective gas supplied.

The evacuation and / or the supply of protective gas is carried out either by an evacuation device 12th and / or running a feed device, which via the suction opening 18th Removes air or other gases or supplies a protective gas. The grooves are used to accelerate this approach of feeding or removing 15th provided, which has the cross-section for evacuation or for the supply of protective gas, for example compared to an embodiment with only one annular gap 17th greatly enlarged.

By providing such as grooves 15th formed recesses can optionally also on the annular gap 17th be waived. In this exemplary embodiment, the recesses are in the form of grooves 15th formed, which in the inner wall of the melting cylinder 16 are provided.

Particularly favorable in this embodiment of the 3a and 3b is that the as grooves 15th formed recesses only in a certain position of the injection piston 7th are released. When the injection piston 7th over the piston rod 13 linear in the direction of the discharge opening 9 is moved, the recesses are covered, whereby the cross-section for evacuation or supply to the annular gap 17th is reduced. As a result, ambient air can flow into the melting chamber during the discharge cycle 4th be slowed down.

3c shows an alternative embodiment to the evacuation device in FIG 3a . To evacuate and / or flood the melting chamber with a protective gas 4th to accelerate are holes 22nd provided, which has the cross-section for evacuation or for the supply of protective gas, for example compared to an embodiment with only one annular gap 17th greatly enlarge.

The holes 22nd are in this embodiment in the the melting chamber 4th forming wall (which through the melting cylinder 16 is formed). Since it is not always possible in terms of production technology, the holes 22nd to be arranged in such a way that they only connect to the environment at a predetermined point, sealing plugs can 23 proceed to direct a current individually.

Similar to the 3a are also in this embodiment as bores 22nd formed recesses only in a certain position of the injection piston 7th Approved. When the injection piston 7th over the piston rod 13 linear in the direction of the discharge opening 9 is moved, the recesses are covered, whereby the cross-section for evacuation or supply to the annular gap 17th is reduced.

The 4th shows a detailed view of two identical seals 11 , whereby by means of the seals 11 the bearing housing 3 opposite the piston rod 13 is sealed.

In this particular embodiment, the seals are 11 formed with a tubular cross-section, which is annularly attached to the piston rod 13 applies. The seals 11 also has cavities 20th on which via feed lines 21st forming valve bodies 19th are connected to a supply device for supplying compressed air.

The seals 11 are formed from an elastic rubber material, such as rubber, polyethylene or polytetrafluoroethylene.

By supplying or removing a filling medium (in this embodiment, air), a pressure can be created in the cavities 20th of the seals 11 can be influenced, more precisely even adjusted or regulated, creating a cross-section of the seals 11 can be influenced.

So by pressurizing the seals 11 , more precisely the cavities 20th of the seals 11 , the cross section of the seals 11 can be enlarged or reduced. The cross section of the seals 11 can change due to the installation situation in the bearing housing 3 do not enlarge, which leads to an increased contact pressure of the seal 11 to the piston rod 13 when the pressure in the cavity increases 20th leads.

Accordingly, there is a sealing factor through the seals 11 controllable or regulatable by means of the feed device, whereby a higher seal can be made. If necessary (if necessary when the piston rod moves 13 ) to reduce the sealing factor to avoid unnecessary wear of the seal 11 on the piston rod 13 by avoiding abrasion can reduce the pressure in the cavities 20th of the seals 11 be reduced.

List of reference symbols

1

Melting unit

2

Cooling fins

3

Bearing housing

4th

Melting chamber

5

Ingot

6th

Induction coil

7th

Injection plunger

8th

Application device

9

Discharge opening

10

Opening of the melting chamber

11

poetry

12

Evacuation device

13

Piston rod

14th

Injection device

15th

Groove

16

Melting cylinder

17th

Annular gap

18th

Suction opening

19th

Valve body

20th

cavity

21st

Feed line

22nd

drilling

23

Sealing plug

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2011/035765 A1 [0009]

Claims (15)

Melting unit for a shaping machine, with - a melting chamber (4), the melting unit (1) being designed to melt a material to be arranged in the melting chamber (4), - a discharge device (8), which discharge device (8) is designed to to bring out a melted material from the melting chamber (4), and - an evacuation device (12) and / or protective gas flooding device, which is designed to apply a negative pressure to at least the melting chamber (4), characterized in that the melting chamber (4) on its inner wall and / or the discharge device (8) has at least one recess on an outer surface, so that there is a fluid connection between the inner wall of the melting chamber (4) and the outer surface of the discharge device (8) in at least one position of the discharge device (8) relative to the melting chamber (4) for evacuating the melting chamber (4) and / or for flooding the melting chamber (4) with a Sc protective gas through the evacuation device (12) and / or protective gas flooding device. Melting unit after Claim 1 , characterized in that the at least one recess has a longitudinal gap fluid connection for evacuating the melting chamber (4) and / or flooding the melting chamber (4) with a protective gas through the evacuation device (12) and / or protective gas flooding device, which is passed through an annular gap (17) between the inner wall the melting chamber (4) and outer surface of the discharge device (8) is enlarged. Melting unit according to at least one of the preceding claims, characterized in that several recesses are provided on the inner wall of the melting chamber (4) and / or the outer surface of the discharge device (8). Melting unit according to at least one of the preceding claims, characterized in that the at least one recess is formed by a groove (15). Melting unit according to at least one of the preceding claims, characterized in that the at least one recess is formed by at least one bore (22). Melting unit according to at least one of the preceding claims, characterized in that the at least one recess only provides the fluid connection for evacuating the melting chamber (4) and / or for flooding the melting chamber (4) in a retracted position of the discharge device (8) from the melting chamber (4) ) with a protective gas. Melting unit according to at least one of the preceding claims, characterized in that the melting unit (1) has an induction coil (6) surrounding the melting chamber (4) at least in some areas for inductive melting of a material to be arranged in the melting chamber (4). Melting unit according to at least one of the preceding claims, characterized in that a separating agent can be applied to an inner side of the melting chamber (4), the separating agent being able to prevent a chemical reaction between the melted material and a material of the melting chamber (4). Melting unit according to at least one of the preceding claims, characterized in that the discharge device (8) has an injection piston (7) which is designed to push out the melted material via a discharge opening (9) in the melting chamber (4). Melting unit according to at least one of the preceding claims, characterized in that the melting chamber (4) is made of a non-metallic material, preferably graphite, stone, ceramic, a ceramic alloy or a glass. Melting unit according to at least one of the preceding claims, characterized in that the melting chamber (4) has a cylindrical, in particular circular-cylindrical, inner wall. Melting unit according to at least one of the preceding claims, characterized in that the dispensing device (8) - preferably an injection piston (7) - has a cylindrical, in particular circular-cylindrical, outer surface. Melting unit after Claim 11 and 12th , characterized in that the discharge device (8) is arranged concentrically in the melting chamber (4). Shaping machine, preferably vacuum pressure casting machine, with a melting unit (1) according to one of the preceding claims. Forming machine according to Claim 14 , characterized in that a cavity is provided, whereby the discharge device (8) molten material from the melting chamber (4) can be introduced into the cavity for a shaping process.

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