DE102016123595B4 - Casting furnace for low pressure casting - Google Patents

Abstract

Casting furnace (1) for low pressure casting, with:
an oven pan (2) for receiving a melt (8);
a housing (3) having a chamber (4) for receiving a melt (8), wherein the housing (3) is at least partially disposed within the furnace trough (2) such that a portion of the housing (3) is within an operating range the casting furnace (1) in the furnace trough (2) contained melt (8), the housing (4) comprising:
a first valve (17) for controlling a flow of melt (8) from the furnace trough (2) into the chamber (4);
a riser (13) for feeding melt (8) from the chamber (4) into a mold; and
a channel (18) for supplying and discharging gas into or out of the chamber (4); and one
in the housing (3) arranged dividing wall (25) dividing the chamber (4) into a first (24) and a second region (26), wherein the first valve (17) in the first region (24) and the riser (13) are arranged in the second region (26).

Description

area

The invention relates to a casting furnace for low pressure casting.

background

Low-pressure casting is a frequently used process for the production of castings, in particular of light metals such as aluminum or magnesium. Usually, pressure-tight furnace containers with or without crucible are used for this process. During the casting process, the entire furnace body is pressurized to allow the melt to rise through a riser into the mold.

Out EP 0 609 196 A1 a casting furnace is known, in which the melt is passed from a storage container via a lock into a removal chamber.

Out EP 1 894 648 A1 is a casting furnace comprising a dip cylinder and a pressure piston known. By the pressure piston, the melt can be actively pressed into a riser. As a result, volume shrinkage during casting can be compensated.

The other pamphlets DE 32 14 922 C2 . DE 694 25 443 T2 . DE 23 04 257 A and DE 10 2009 051 879 B3 also show exemplary casting furnaces from the prior art.

The casting furnaces from the prior art have the disadvantage that high volume flows of compressed and pre-dried compressed gas are required. The compression and drying of the compressed gas is very energy-consuming. This results in high operating costs. In addition, the quality of the melt deteriorates due to oxidation processes on the surface of the melt. This has the consequence that the melt must be treated during the casting process. In addition, the deposition of oxides creates an increased cyclic cleaning requirement.

The invention therefore has for its object to provide a casting furnace which avoids or reduces this disadvantage.

Brief description of the invention

This object is achieved by the invention specified in the independent claims. Advantageous developments can be found in the dependent claims.

According to the invention, there is provided a casting furnace for low-pressure casting, comprising a furnace trough for receiving a melt, a housing having a chamber for receiving a melt, wherein the housing is at least partially disposed within the furnace trough, so that a part of the housing within a during operation of the Casting furnace contained in the furnace trough melt, the housing comprising a first valve for controlling a flow of melt from the furnace trough into the chamber, a riser for supplying melt from the chamber into a mold; and a passage for supplying and discharging gas into and out of the chamber, and a partition disposed in the housing dividing the chamber into first and second regions, the first valve in the first region and the riser in the first region second area is arranged.

The invention is based on the finding that for the actual casting process, the "shot", substantially smaller amounts of melt are required than are usually kept in a furnace. By using a further housing in the furnace trough, it is achieved that only one quantity of melt required in each case for one shot has to be moved. In other words, in the housing, as in a pump, only a small portion of the entire melt is pressurized and moved. For this purpose, on the one hand much smaller amounts of preheated, dried compressed gas necessary and on the other hand, the casting process can run faster. This saves energy and reduces the cost of ownership of the caster. Another advantageous effect is that in the housing a much lower surface of the melt is exposed to the compressed gas. As a result, oxidation processes and associated impurities are reduced. In particular, oxidations of the melt occurring in the furnace tub are reduced because they do not come into contact with pressurized gas. This leads to significantly longer cleaning cycles and thus improved utilization of the caster. By arranging the first valve in the first region of the chamber, the second region is filled by flowing melt from the first region via the dividing wall into the second region. The second area is dimensioned such that sufficient melt is available in it for the casting process. If a pressure is built up in the chamber for the casting process, only the melt from the second region escapes through the riser pipe into a casting mold. If the first valve has a leak in the first area, then it is ensured that only the melt from the first area flows back into the furnace trough. This has the advantage that, even with leaks in the valve, sufficient melt is always available for the casting process.

In one embodiment of the invention, the riser has a second valve to prevent backflow of melt from the mold into the chamber. When filling the chamber after a Geißvorgang the applied vacuum causes no backflow of (residual) melt from the riser into the chamber. This prevents "fresh" melt from being contaminated by "old" melt.

In one embodiment of the invention, the housing comprises a lid and is closed by pressure-tight means of the lid, in particular, the riser is passed through the lid. The lid is removable and allows access to the chamber and to the riser. This facilitates cleaning.

In one embodiment of the invention, the housing comprises probes, in particular temperature probes, for detecting states within the chamber. By means of the probes, for example, the temperature of the melt, the viscosity of the melt, the composition of the gas above the bath play gel in the chamber, or the fill level in the chamber can be detected. The probes make it possible to run the casting process in a controlled manner.

In one embodiment of the invention, the channel opens into the chamber in the region of the lid. The compressed gas is thus introduced above the Badspielgels in the chamber. This avoids blistering in the melt and reduces the oxidation processes in the chamber.

In one embodiment of the invention, the first valve is arranged in a bottom of the housing and the bottom of the housing is in the filled state of the cast furnace below a bath level of the melt in the furnace tub. The first valve is thus always below the bath level of the melt in the furnace tub. This ensures that when a vacuum is applied to the housing, melt will always flow from the furnace pan into the housing and fill the chamber.

In one embodiment of the invention, the channel is formed as at least partially extending in the cover tube coil. Accelerated pressurized gas is preheated within the lid by the autogenous temperature of the caster. As a result, the energy required to heat the compressed gas can be reduced.

In one embodiment of the invention, the housing is made of a thermally conductive material, in particular ceramic. There may be a heat transfer between the melt in the furnace tub and the housing. This can be dispensed with own heating elements in or on the housing. The housing is co-heated by the heating elements of the furnace tub. This additionally reduces the energy consumption.

In one embodiment of the invention, the furnace trough heating elements, in particular immersion heater, wherein the heating elements are arranged in the region of a trough bottom. The arrangement of the immersion heaters on a bottom of the furnace tub creates an uneven heat distribution within the melt. This creates a vertical circulation within the melt. The circulation prevents heavier components of the melt settling on the bottom of the furnace trough. The heavier components of the melt are held in suspension and co-processed. The quality of the melt can thus be kept constant high over a longer period.

According to a second aspect of the invention there is provided apparatus for receiving a melt for a low pressure casting casting furnace, the apparatus comprising a housing having a chamber for receiving the melt, the housing being at least partially disposable within a furnace trough of a casting furnace such that a portion of the housing is within a melt contained in the furnace trough during operation of the caster furnace, the housing comprising a first valve for controlling a flow of melt from the furnace trough into the chamber, a riser for feeding melt from the chamber into a casting mold, and a channel for supplying and discharging gas into or out of the chamber, and a partition disposed in the housing dividing the chamber into first and second regions, the first valve in the first region and the riser in the second region Area is arranged. According to this aspect, the device can be integrated into existing casting furnaces. Pouring furnaces are therefore retrofittable with the device and can be made more economical. The above-described optional design features of the caster are individually or in combination also applicable to the device according to the second aspect of the invention.

list of figures

• Die 1 eine beispielhafte Ausführungsform des erfindungsgemäßen Gießofens;
• die 2 eine beispielhafte Ausführungsform einer Kammer des erfindungsgemäßen Gießofens; und
• die 3 eine weitere beispielhafte Ausführungsform einer Kammer des erfindungsgemäßen Gießofens.

Hereinafter, exemplary embodiments of the invention are described in more detail with reference to the accompanying drawings. Show it:

• The 1 an exemplary embodiment of the casting furnace according to the invention;
• the 2 an exemplary embodiment of a chamber of the casting furnace according to the invention; and
• the 3 a further exemplary embodiment of a chamber of the casting furnace according to the invention.

figure description

1 shows an exemplary casting furnace 1 according to an embodiment of the invention. The casting furnace 1 has an oven tray 2 and a housing disposed therein 3 with a first chamber 4 on. The oven pan 2 has a filling opening 5 on. heating elements 6 are in the area of a floor 7 the furnace tub 2 arranged and in the filled state of the caster 1 always completely from a melt 8th surround. The heating elements 6 are immersion heaters and are in direct contact with the melt 8th , The oven pan 2 is from an insulation 12 surround.

The melt 8th is through the filling hole 5 in the oven pan 2 filled and forms a melt bath with a first bath level 9 , The filling opening 5 is through a melt 8th projecting wall element 10 from a second chamber 11 the furnace tub 2 separated. The filling opening 5 and the second chamber 11 are below the first bathroom mirror 9 communicating with each other.

Inside the second chamber 11 there is the first chamber 4 in the case 3 , The housing 3 consists of a good heat-conducting material. The housing 3 extends in the vertical direction in the melt 8th in the second chamber 11 , so it is at least partially melted 8th is surrounded. The bottom of the case 3 is in the filled state of the caster below the first bath level 9 ,

Inside the case 3 is a vertical riser 13 arranged. The housing 3 is with a lid 14 pressure-tight lockable, with the upper end of the riser 13 through the lid 14 extends. The lid 14 has as well as the furnace tub 2 an insulation 15 on. The housing 12 points to its underside 16 a feed valve 17 on. The housing 12 is in a ceiling area 19 the furnace tub 4 integrated and forms a kind of use in the second chamber 11 ,

2 shows a schematic representation of the housing 3 , In the area of the lid 14 there is a channel 18 , The channel 18 serves both to apply a pressure and to create a vacuum in the first chamber 4 , The channel 18 flows above a second bath level 20 the melt 8th in the second chamber 3 ,

The riser 13 is arranged vertically within the second chamber. The riser 13 just above the floor of the first chamber 4 an opening 21 on. The opening is through a second, passive valve 22 locked. The second valve 22 prevents when applying a vacuum, melt 8th from a (not shown) casting mold through the riser 13 in the first chamber 4 can flow back. Through the lid 14 through are probes 23 guided. The probes 23 serve to determine the height of the second bath level 20 and the temperature of the melt in the first chamber 4 ,

3 shows a further embodiment of the first chamber 4 , The housing 3 has in this variant a separate first area 24 and up. The first area 24 is through a partition 25 from a second area 26 the first chamber 4 separated. The valve 17 lies in the first area 24 and is thus through the partition wall 25 from the rest of the first chamber 4 separated.

In the operation of the caster is the housing 3 according to 1 in the oven pan 2 inserted and through the lid 14 sealed pressure-tight. The oven pan 2 is up to the first bathroom mirror 9 with melt 8th filled. The housing 3 is in the melt 8th immersed, so that the bottom of the case 16 below the first bath mirror 9 located. The first chamber 4 of the housing 3 is up to the second bathroom mirror 20 with melt 8th filled. For the actual casting process, the "shot", the first chamber 4 over the canal 18 pressurized by introducing a pressurized gas. The compressed gas presses on the second bath level 20 and shoot the melt 8th through the riser 13 in the mold (not shown). The valve 22 opens and allows the flow of melt 8th through the riser 13 , As long as an overpressure in the first chamber 4 exists, the valve locks 17 and prevents melt backflow 8th in the oven pan 2 , The outflow of melt ends when the second bath level reaches the level of the opening 21 of the riser 13 has fallen off. This is done by the probes 23 detected, and the influx of compressed gas is stopped. The inflow can also be stopped even if a defined volume of melt through the riser 13 has flowed into the mold.

To one according to 2 trained first chamber 4 back to a desired level with melt 8th to fill, is through the channel 18 created a vacuum. When the vacuum is applied, the valve opens 17 and allows the influx of melt 8th from the second chamber 11 the furnace tub 2 in the first chamber 4 , As soon as the second bathroom mirror 20 Once again reaches a desired level, the vacuum is reduced again. The desired level is also determined by the probes 23 detected and degraded the vacuum based on this detection.

To one according to 3 trained first chamber 4 back to a desired level with melt 8th to fill, is through the channel 18 created a vacuum. When the vacuum is applied, the valve opens 17 and melt 8th flows through the valve 17 first in the first area 24 , When the melt 8th in the first area 24 the level of the partition 25 has reached, this flows over the partition 25 in the second area 26 the first chamber 4 , The influx ends when the second bathroom mirror 20 in the first chamber 4 the level of the partition 25 has reached.

In the casting process, "the shot" both areas 24,26 of the first chamber 4 over the canal 18 pressurized by introducing a pressurized gas. When filled, there is a required amount of melt for the shot 8th in the second area 26 the first chamber 4 , The built-up pressure presses on the bathroom mirror 20 in the first area 24 and the second area 26 , This will cause the melt 8th from the second area 26 through the riser 13 pressed into the mold. The melt 8th in the first area 24 stays behind. If the valve 17 should be leaking, when applying a pressure, only the proportion of melt 8th from the first area 24 in the oven pan 2 flow back. This ensures that leaks of the valve 17 have no influence on the casting process.

LIST OF REFERENCE NUMBERS

1

casting furnace

2

furnace shell

3

casing

4

first chamber

5

fill opening

6

heating elements

7

ground

8th

melt

9

first bathroom mirror

10

wall element

11

second chamber (the furnace tub)

12

insulation

13

riser

14

cover

15

Insulation of the lid

16

Housing bottom

17

(Zustrom-) valve

18

channel

19

ceiling area

20

second bathroom mirror

21

Opening of the riser

22

second valve

23

probes

24

first area

25

partition wall

26

second area

Claims (10)

Casting furnace (1) for low pressure casting, with: an oven pan (2) for receiving a melt (8); a housing (3) having a chamber (4) for receiving a melt (8), wherein the housing (3) is at least partially disposed within the furnace trough (2) such that a portion of the housing (3) is within an operating range the casting furnace (1) in the furnace trough (2) contained melt (8), the housing (4) comprising: a first valve (17) for controlling a flow of melt (8) from the furnace trough (2) into the chamber (4); a riser (13) for feeding melt (8) from the chamber (4) into a mold; and a channel (18) for supplying and discharging gas into or out of the chamber (4); and one in the housing (3) arranged dividing wall (25) dividing the chamber (4) into a first (24) and a second region (26), wherein the first valve (17) in the first region (24) and the riser (13) are arranged in the second region (26). Casting furnace (1) after Claim 1 wherein the riser (13) has a second valve (22) to prevent backflow of melt (8) from the mold into the chamber (4). Casting furnace (1) according to one of the preceding claims, wherein the housing (3) comprises a cover (14) and by means of the lid (14) is pressure-tight lockable, in particular wherein the riser (13) is passed through the lid (14). Casting furnace (1) according to one of the preceding claims, wherein the housing (3) probes (23), in particular temperature probes, for detecting states within the chamber (4). Casting furnace (1) according to one of the preceding claims, wherein the channel (18) in the region of the lid (14) opens into the chamber (4). Casting furnace (1) according to one of the preceding claims, wherein the first valve (17) in a bottom (16) of the housing is arranged and the bottom of the housing (16) in the filled state of the caster (1) below a bath level (9) of the Melt (8) in the furnace tub (2) is located. Casting furnace (1) after Claim 1 wherein the channel (18) is formed as at least partially in the lid (14) extending tube coil. Casting furnace (1) according to one of the preceding claims, wherein the housing (3) made of a thermally conductive material, in particular ceramic, is formed. Casting furnace (1) according to one of the preceding claims, wherein the furnace trough (2) heating elements (6), in particular immersion heater, wherein the heating elements (6) are arranged in the region of a trough bottom. Apparatus for receiving a melt (8) for a casting furnace (1) for low-pressure casting, the apparatus comprising: a housing (3) having a chamber (4) for receiving the melt (8), wherein the housing (3) can be arranged at least partially within a furnace trough (2) of a casting furnace (2) so that a part of the housing (3 ) within a melt contained in the furnace trough (2) during operation of the caster (1), the housing (3) comprising: a first valve (17) for controlling a flow of melt (8) from the furnace trough (2) into the chamber (4); a riser (13) for feeding melt (8) from the chamber (4) into a mold; and a channel (18) for supplying and discharging gas into or out of the chamber (4); and one in the housing (3) arranged dividing wall (25) dividing the chamber (4) into a first (24) and a second region (26), wherein the first valve (17) in the first region (24) and the riser (13) are arranged in the second region (26).

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