GB2266945A - Tank furnace for low pressure injection casting - Google Patents
Tank furnace for low pressure injection casting Download PDFInfo
- Publication number
- GB2266945A GB2266945A GB9218589A GB9218589A GB2266945A GB 2266945 A GB2266945 A GB 2266945A GB 9218589 A GB9218589 A GB 9218589A GB 9218589 A GB9218589 A GB 9218589A GB 2266945 A GB2266945 A GB 2266945A
- Authority
- GB
- United Kingdom
- Prior art keywords
- furnace
- heating element
- tank furnace
- low pressure
- pressure injection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000002347 injection Methods 0.000 title claims abstract description 22
- 239000007924 injection Substances 0.000 title claims abstract description 22
- 238000005266 casting Methods 0.000 title claims abstract description 8
- 238000010438 heat treatment Methods 0.000 claims abstract description 26
- 239000002184 metal Substances 0.000 claims abstract description 20
- 230000002093 peripheral effect Effects 0.000 claims 1
- 238000001816 cooling Methods 0.000 abstract description 2
- 238000007711 solidification Methods 0.000 abstract 1
- 230000008023 solidification Effects 0.000 abstract 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 2
- 238000007664 blowing Methods 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000003467 diminishing effect Effects 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D18/00—Pressure casting; Vacuum casting
- B22D18/04—Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
- F27B3/08—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces heated electrically, with or without any other source of heat
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D11/00—Arrangement of elements for electric heating in or on furnaces
- F27D11/02—Ohmic resistance heating
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D2003/0034—Means for moving, conveying, transporting the charge in the furnace or in the charging facilities
- F27D2003/0054—Means to move molten metal, e.g. electromagnetic pump
- F27D2003/0056—Means to move molten metal, e.g. electromagnetic pump through a syphon in a vacuum chamber, e.g. involving aspiration or pressure on the bath
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D99/00—Subject matter not provided for in other groups of this subclass
- F27D99/0001—Heating elements or systems
- F27D99/0006—Electric heating elements or system
- F27D2099/0008—Resistor heating
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Crucibles And Fluidized-Bed Furnaces (AREA)
- Resistance Heating (AREA)
- Vertical, Hearth, Or Arc Furnaces (AREA)
Abstract
In a tank furnace (F) for low pressure injection casting, one or more heating element loops (R) that maintain the metal at a temperature higher than the solidification temperature extend round the interior of the furnace, just above the maximum level of the molten metal. This allows the furnace (F) to be compact, makes efficient use of the energy radiated by the heating element loops (R) and permits an injection duct (I) to be of short length, thereby reducing the likelihood of bubbles forming in or metal cooling too much in the injection duct (I). <IMAGE>
Description
TANK FURNACE FOR LOW PRESSURE INJECTION CASTING
The invention relates to a tank furnace for low pressure injection casting.
At present, a holding furnace for low pressure injection casting comprises a crucible, isolated from the atmosphere, which is separate from the surrounding housing and cover (a "crucible" furnace) or provided directly by a layer of appropriately shaped thermoinsulating refractory material (a "tank" furnace). A vertical duct connects the liquid metal within the crucible to a die on the cover of the furnace. The liquid metal is introduced into the crucible and is kept in the liquid state by means of electric heating devices, such as (i) wire-wound resistances arranged like a cylinder along the external wall of the crucible (an independent crucible furnace) or (ii) heating bars (plugs) placed transversely above the melted metal (a tank furnace).
By blowing compressed air into the furnace, the metal is pushed along the injection duct and into the die.
In the injection phase, the air in the duct and in the die is evacuated by means of special orifices, but air and/or gas bubbles can form along the vertical duct. Their quantity and dimensions are directly correlated to the temperature and length of the injection duct itself. Furthermore, there can be a subcooling of the metal along the duct, mainly in independent crucible furnaces, which can cause injection difficulties and be prejudicial to the quality of the finished product. Such subcooling is dependent on the distance between the heating elements and the injection duct.
According to the present invention, there is provided a tank furnace for low pressure injection casting, wherein one or more heating element loops for heating molten metal extend round the interior of the furnace, above a maximum level for the molten metal.
The heating element loops heat the molten metal and the injection duct and, even though in the interior of the furnace, they do not touch the molten metal. The furnace may be made with a reduced height, thereby diminishing the distance travelled by the metal when it is injected into a die. This reduces the risk of bubbles forming.
The heating element loops may be provided by separate heating elements or a single spiral heating element. In any event, because the injection duct is inside the heating element loops, it is heated by them. In an embodiment, the heating element loops are housed in suitable seats around the internal wall of the furnace, just above the maximum level that can be reached by the molten metal. Their position is such as to ensure maximum protection against being splashed by molten metal during filling of the furnace. A cover of the furnace is just above the heating element loops, and the refractory covering of the cover has a section like a downwardly pointing frustum of a cone.
The heat produced by the heating element loops is directed to the molten metal and the injection duct. The result is a reduced loss of heat, uniform heating and a considerable energy saving compared with traditional methods.
The invention will now be described by way of non-limiting embodiments with reference to the accompanying drawings, in which
Figures 1 and 2 are cross-sections through respective embodiments of tank furnaces in accordance with the invention.
The Figures show alternative configurations of the heating system.
For the sake of clarity, only the parts most relevant to the invention will be described. Less relevant parts, such as temperature sensors, gauges, various levers, dies etc. will not be described.
Each furnace F has a side hole A with a lock, so as to permit the introduction of molten metal into the furnace. The furnace F is closed by a cover C in which, at the centre or offcentre, is a vertical injection duct I for transferring the molten metal from the furnace to a die on the cover.
Resistive heating elements R on the internal wall of the furnace F are arranged on circumferences with equal diameters, on circumferences with diameters which decrease in the upward direction, or in a spiral. The part of the heating element housing above each heating element extends towards the centre of the tank, so as to better direct the thermic radiation of the heating element towards the molten metal and the injection duct.
The thickness of the cover C of the furnace F is not constant: it is thinner around the edge and thicker in the middle.
The arrangement of the heating elements R and the shape of the cover C allow a reduction in height of the furnace, with a consequent decrease in length of the injection duct I. This reduces the risk of bubbles forming during injection and the risk of excessive cooling of the metal in the duct I
The above schematic embodiments are sufficient for the skilled person to implement the invention. Furthermore, modifications may be made to the illustrated embodiments without thereby departing from the invention.
Claims (6)
1. A tank furnace for low pressure injection casting, wherein one or more heating element loops for heating molten metal extend round the interior of the furnace, above a maximum level for the molten metal.
2. A tank furnace according to claim 1, wherein a plurality of the heating element loops have diameters which decrease in the upward direction.
3. A tank furnace according to claim 1 or 2, wherein a spiral heating element provides a plurality of the heating element loops.
4. A tank furnace according to claim 1, 2 or 3, further comprising a cover whose bottom surface is lower at a central portion than at a peripheral portion which supports the central portion.
5. A tank furnace for low pressure injection casting, substantially as herein described with reference to, or with reference to and as illustrated in, the accompanying drawings.
6. All novel features and combinations thereof.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ITPD920082A IT1259097B (en) | 1992-05-08 | 1992-05-08 | LOW PRESSURE BASIN OVEN ELECTRICALLY HEATED BY SPIRAL HEATING ELEMENTS ABOVE THE BATH LEVEL |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9218589D0 GB9218589D0 (en) | 1992-10-14 |
| GB2266945A true GB2266945A (en) | 1993-11-17 |
Family
ID=11389923
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9218589A Withdrawn GB2266945A (en) | 1992-05-08 | 1992-09-02 | Tank furnace for low pressure injection casting |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA2075269A1 (en) |
| GB (1) | GB2266945A (en) |
| IT (1) | IT1259097B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0697577A1 (en) * | 1994-04-28 | 1996-02-21 | NIPPON MINING & METALS COMPANY, LIMITED | Vacuum melting - pressure pouring induction furnace |
| CN105987597A (en) * | 2015-01-29 | 2016-10-05 | 边仁杰 | Bottom plate of regenerative furnace |
| CN105987596A (en) * | 2015-01-29 | 2016-10-05 | 边仁杰 | Bottom coil of heat-insulation furnace |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB468997A (en) * | 1935-10-19 | 1937-07-16 | Saint Gobain | Improvements relating to electric radiation furnaces |
| GB788525A (en) * | 1955-05-20 | 1958-01-02 | Ferdinand Leferrer | Improvements in or relating to the recovery of zinc from the zinc crust obtained in the separation of silver from lead |
| GB1539412A (en) * | 1975-01-17 | 1979-01-31 | Schaefer Inc F | Metallurgical furnaces |
| GB1561786A (en) * | 1976-12-09 | 1980-03-05 | Ass Eng Ltd | Heating vessles for molten metal |
-
1992
- 1992-05-08 IT ITPD920082A patent/IT1259097B/en active IP Right Grant
- 1992-08-04 CA CA002075269A patent/CA2075269A1/en not_active Abandoned
- 1992-09-02 GB GB9218589A patent/GB2266945A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB468997A (en) * | 1935-10-19 | 1937-07-16 | Saint Gobain | Improvements relating to electric radiation furnaces |
| GB788525A (en) * | 1955-05-20 | 1958-01-02 | Ferdinand Leferrer | Improvements in or relating to the recovery of zinc from the zinc crust obtained in the separation of silver from lead |
| GB1539412A (en) * | 1975-01-17 | 1979-01-31 | Schaefer Inc F | Metallurgical furnaces |
| GB1561786A (en) * | 1976-12-09 | 1980-03-05 | Ass Eng Ltd | Heating vessles for molten metal |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0697577A1 (en) * | 1994-04-28 | 1996-02-21 | NIPPON MINING & METALS COMPANY, LIMITED | Vacuum melting - pressure pouring induction furnace |
| US5559827A (en) * | 1994-04-28 | 1996-09-24 | Nippon Mining & Metals Co., Ltd. | Vacuum melting-pressure pouring induction furnace |
| CN105987597A (en) * | 2015-01-29 | 2016-10-05 | 边仁杰 | Bottom plate of regenerative furnace |
| CN105987596A (en) * | 2015-01-29 | 2016-10-05 | 边仁杰 | Bottom coil of heat-insulation furnace |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9218589D0 (en) | 1992-10-14 |
| ITPD920082A1 (en) | 1993-11-08 |
| CA2075269A1 (en) | 1993-11-09 |
| IT1259097B (en) | 1996-03-11 |
| ITPD920082A0 (en) | 1992-05-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |