Patent Application
20210197253
This invention benefits from my existing design and utility patents and improves the invention.
Not applicable
The subject matter of the claimed invention falls within the US patent classification definition, F27D 99/00, F27D 2001/0063, F27D/0066.
The invention Ceramic Metal Riser Tube stalk is concerned with Low Pressure Die Casting (LPDC) process. Molten metal is transferred under gas pressure from furnace to casting die through Ceramic Metal Riser Tube stalk.
The invention provides extended service life and improves casted part quality. It can replace existing riser tubes without any modification to casting machines, casting dies or feeder systems.
As used herein the term molten metal means any metal or combination of metals in liquid form such as aluminium, copper, iron and their alloys in thereof. The term gas means any gas or combination of gases including atmospheric air, argon, nitrogen or other gasses applied onto molten metals. The subject matter (
Conventionally two types of riser tubes are used in process of Low Pressure Die Casting. These riser tubes have a short and unpredictable life, causing quality problems in products being cast and major down time problems. Riser tubes made from metallic materials tend to dissolve in molten metal being transferred, leading to contamination of molten metal and riser tube failure. Riser tubes made from ceramic materials have resistance to molten metals but are mechanically weak and easily damaged by mechanical loading, mechanical shock, thermal shock and oxidised metal accumulation on its surfaces. Metallic insert application on a ceramic tube leads to cracking, caused by different rates of expansion. Metallic insert application suffers with problems of gas leak into the product being cast. These tubes are often very expensive, require special skills to assemble and carry all the problems of ceramic riser tubes. Once any part of the riser tube is damaged or cracked, it becomes unusable and must be replaced. Damaged tubes are not re-usable.
The invention is designed with a combination of metallic materials and ceramic materials, providing both properties of mechanical strength and resistance to molten metal. The function of invention is not affected by mechanical loading, mechanical shock or damage to the ceramic materials, for example cracks and chips. Gas leak into products being cast is not possible. It is possible to reuse metallic components of the invention.
Various materials are disclosed in the following detailed description and accompanying drawings.
Design of Riser tube stalk consists of following components
(1) Neck; it is shapped to match various casting machine designs and is part of the main body of riser tube. Neck-less design is also adopted when interagted flange (3) is designed within the main body (4) of the Riser tube stalk.
(2) Sealing slots; Feature provided in the form of slots to hold sealing material between metallic and ceramic parts of the riser tube. Mechanical sealing is achieved by using very high temperature sealing compounds. The sealant has working temperatures of over 1200° C. and is shapped to the slot profile. Shape and quantity of slots vary according to level of sealing required. Some riser tubes may not require sealing slots where a different type of sealant can be applied in the form of expansion filler (10).
(3) Integrated flange; The flange is an integrated feature of this design. It can be of any dimension in shape, diameter and height. Since the flange is cast or machined with the main body (4) of riser tube stalk, it does not require any assembly, sealing or preparation therefore providing a gas tight operation and better quality of castings made on Low Pressure Die Casting machines. Integrated flange can bear high mechanical loads without damaging the tube.
(4) Main body; made from metal that is resistant to wear and chemical reaction from molten metal. It provides gas tight function for Low Pressure Die Casting process while molten metal is being transferred through the Ceramic steel riser tube stalk. The main body metallic design also provides mechanical strength and support to ceramic components of riser tube stalk. The main body is further treated to improve its strength and chemical properties. It can be made from various specifications of iron (Fe) alloys or other metals according to operational environment and cost constraints. It can be cast or machined in to the required shapes including tubular shapes to match various casting machine designs. The bottom end of main body is designed for securing parts to the main body. Threaded holes (8) are used for assembling retainer cap (7) to the main body (4).
(5) outer protection; Riser tube stalk operates in direct contact with molten metals at temperatures over 700° C. leading to wear caused by chemical reactions. A protection layer of barrier materials is applied in the form of a coating or sleeve. Barrier materials range from brush on coatings to advanced thermal or plasma sprayed metallic oxides and metallic ceramic sleeves, for example aluminium oxides, Zirconium, Tungsten, Molybdenum refractory materials or other compositions that are resistant to molten metals. Outer protection (5) when used as sleeve can be installed in single, double or multiple pieces. Outer protection is designed in a manner so it can be replaced.
(6) inner protection; Internal diameter or shape of main body (4) is protected from chemical and heat reaction of molten metals by using barrier materials. Barrier can be designed in any shape to match internal shape of the main body (4). Barrier materials range from brush on coatings to advanced thermal or plasma sprayed metallic oxides and metallic ceramic sleeves, for example aluminium oxides, Zirconium, Tungsten, refractory materials or any other compositions that are resistant to molten metals. Inner protection (6) when used as sleeve can be installed in single, double or multiple pieces. Inner protection is designed in a manner so it can be replaced.
(7) Retainer cap; Is a part of the Riser tube stalk to keep ceramic sleeves or tubes (5) and (6) in assembled position. Retainer cap also retains any bottom filter elements used in Low Pressure die casting process. Removeable or sacrificial retainer cap allows additional filter replacement. Retainer cap is made from metallic ceramics or metals with melting points above 1400° C. The main body of the Riser tube (4) can be designed in a manner that no retainer cap is neccesory or other retaining methods can be applied.
(8) Retainer cap fasteners; Retainer cap (7) is assembled to the main body (4) by using screw, bolts or pins made from metallic ceramics or metals with melting temperatures above 1500° C. Other cements, high temperature adhesives, ceramic fasteners and other securing methods are also used to fasten the retainer cap (8) to the main body (4).
(9) Lifting bolt holes; bolt holes are provided in the riser tube main body (4) flange area (3) for safe lifting. An eye bolt or other lifting accessory can be screwed in for lifting device coupling.
(10) Expansion filler;
The invention Ceramic Metal Riser Tube stalk uses material that are strong and resistant to molten metal and corrosion. Materials used in this invention may have different rates of thermal expansion, a layer of expansion absorbing material is used to compensate for the size changes without damaging the components in Ceramic Metal Riser tube stalk. Filler materials range from ceramic fibres, cements, clays and high temperature materials such as graphite and graphite impregnated ceramic fibres or combination. benefits.
