WO2013085401A1

WO2013085401A1 - Cooling plate

Info

Publication number: WO2013085401A1
Application number: PCT/PL2011/000140
Authority: WO
Inventors: Piotr Kowalski; Zbigniew PĄCZEK; Krzysztof WAŃCZYK; Józef GALON
Original assignee: Przedsiębiorstwo Innowacyjne Odlewnictwa Specodlew - Sp. Z O. O.
Priority date: 2011-12-05
Filing date: 2011-12-21
Publication date: 2013-06-13
Also published as: PL397245A1; PL219714B1

Abstract

The present invention refers to a cooling plate for the material casted in casting moulds. The cooling plate (7) has the base of any shape. Inside the body of the plate (7) there is a hollow channel (12) in the shape of a double coil through which a cooling agent flows. Between the channel (12) there is a channel (13) through which a cooling agent with a lower temperature flows. Along the path of the channel (12) there are ports in which slot nozzles (11) and/or straight nozzles (8) and/or nozzles with an adjusted flow direction (9) and/or multipoint nozzles (10) are installed. Under the bottom of the sand mould (1) mounted on the cooling plate (7) between the bottom of the mould (1) and the upper surface of the cooling plate (7), there is a cooling agent flow chamber (5). The cooling plate (7) is mounted at the casting station, where under the bottom of the cooling plate (7) there is a chamber through which the agent cooling the bottom surface of the cooling plate (7) flows. Between the cooling plate (7) and the bottom of the casting (2) there is a separating layer (3) of the sand mould (1) inside which/ in the sand channels (4), there are straight nozzles (8), slot nozzles (11), and nozzles with an adjusted flow direction (9). For castings that are oval in shape, the cooling element is equipped with additional multipoint nozzles (10).

Description

Cooling Plate

The present invention refers to a cooling plate that is used to control the casting solidification and cooling process, preferably installed at the casting station.

The invention is used, in particular, during casting in sand moulds and in ceramic moulds, where it is also used for the so-called treatment of materials.

The casting in casting moulds consists in feeding liquid metal into a mould, where the metal solidifies and transfers heat to the mould. During this solidification, complex chemical and physical processes occur in the mould. The process of solidification of the casted material distributed in space and time has a deciding impact on the created structure of the obtained casting and its mechanical properties.

During the casting solidification in the mould, the mechanical properties of the casting, including the casting stresses, are significantly affected by the space and time of the cooling of the casted material. When the mould is filled with liquid metal, the casted material heats the mould within a short period of time. The longer the cast stays in the mould, the longer the cooling time of the casting. The cooling time of the casted material is relatively long compared to its solidification time. For the castings of significant volumes, the cooling of the casting to the temperature that enables the commencement of the process of knocking the casting out, usually takes several days, or even several weeks.

In the well-known state of the art, the materials accelerating heat transfer from the castings include chills arranged in the sand mould. The used chills are usually made of materials with significant heat accumulation, which in most cases is cast iron or the same material as the casting. The chills are arranged in the mould outside and inside the casting. The external chills are placed in the moulds in such a way so that they fit tightly to the casting surface without fusing with the casting. Internal chills are placed directly inside the mould cavity. After filling the mould with the liquid metal, they form an internal part of the casting. The size of each chill is selected taking into account the casting thickness and the size of hot spots. However, the chills are very often used to limit the hot spots and quite often to the separate feeding zones of the casting.

The Polish patent specification No. 186378 entitled "Metal casting method", presents a bottom cooler used for transferring heat from the casting, which forms an independent pipe system for the local or bottom transfer of heat from the casting. Local or bottom heat removal from the casting takes place as a result of the flow of compressed air through the pipe system. Independent local pipe systems and the bottom pipe system form the casting cooling system executed in several designated spatial zones of the mould and it is controlled in each zone separately.

A disadvantage of the devices and materials accelerating heat transfer from the casting, known from the state of the art, is an excessively slow process of cooling the casted material. When using the cooling system known from the state of the art by applying independent local pipe systems, the following turns out to be unsatisfactory: the speed of the cooling process and a complex structure of assembly of the local pipe systems. These devices and materials known from the state of the art fail to eliminate stresses that occur inside the casting during solidification and then cooling.

During the solidification of castings as a result of metal crystallisation, a specific metallographic structure is formed in the casted product. The relation between the grain structure refinement and the increase in the speed of heat transfer is known. The refined structure formed in the casting results in an increase in the strength and hardness of the material fed to the mould.

The acceleration of the process of solidification and, in particular, the process of solidification and cooling in casting moulds is specifically important in the areas of hot spots, in which the use of feedheads is impossible for technological reasons.

The plate for cooling the material casted in the casting moulds, according to the invention, has an appropriately adjusted structure and its base may be of any shape depending on the size and shape of the casting. The cooling plate enables the control of the process of solidification and the process of cooling castings in casting moulds, in particular in sand moulds. The cooling plate is made of a material that easily absorbs heat energy, such as steel or another alloy, among others. Preferably, the cooling plate forms the bottom part of the mould or the base placed under the moulds before they are fed with liquid metal. At the place of mould feeding, one or more cooling plates are installed. A casting mould or casting moulds are placed on the installed cooling plate, depending on the size of its surface. An appropriate structure of the cooling plate is adjusted to the shape of the casting for which the casting mould is designated, in particular a sand mould. Preferably for the needs of the invention, there is also a cooling agent flow chamber constructed between the cooling plate and the casting mould. Preferably, the cooling agent flow chamber is constructed under the bottom of the cooling plate installed at the place of mould feeding, below the installed cooling plate. In this chamber there is additional cooling of the bottom surface of the cooling plate. Inside the metal body of the cooling plate, there are hollow channels, the shape of which depends on the type of the cooled casting, the assumed speed of casting cooling and the location of hot spots in the casting. These channels form openings along the cooling plate and/or across the cooling plate and/or they form a spiral and/or coil or have another shape that is required to accelerate heat removal by the cooling agent flowing through the channel (s) . Preferably, the cooling plate has two types of channels independent of each other with a properly adjusted shape of the path inside the body. The agent, cooling the plate body and the external walls of the casting, flows through one of these channels, and the cooling agent with a lower temperature for cooling the metal body of the cooling plate flows through the other channel. To accelerate the cooling of the casting, the internal channels have properly selected ports for the cooling agent, to which the nozzles of a different structure are mounted. These ports are placed from the side of interface between the cooling plate and the layer of the moulding sand separating the cooling plate from the external walls of the casting and they are in the immediate proximity of the ceramic wall of the casting mould. The ports for the mounting nozzles are plugged or open, as required, especially in places where hot spots of the casting occur. Once the port is opened, cool compressed air or other gas agent is blown down into the direction of the separating layer and thereby causes its additional cooling. Nozzles installed in the ports have tips that help direct the blown agent vertically up or perpendicularly to the nozzles and/or are set at the required angle to the casting walls. For ceramic moulds, the agent blown down through the nozzles in the direction of ceramic walls of the mould is preferably constituted by very cold water that is poured or sprayed over the walls of the ceramic mould already during the process of feeding the liquid metal into the mould. The nozzles installed in the ports of the cooling plate have a different height depending on the height of the casting itself and on the location of the casting mould on the cooling plate. Preferably, in the layer of the moulding sand separating the cooling plate from the walls of the casting there are channels for blowdown nozzles installed in the ports of the cooling plate.

To ensure the proper capacity of heat energy absorption by the cooling plate and accelerate the cooling process, the following is used as an agent flowing through the channels of the cooling element: the flow of gas, preferably air with pressure and temperate adjusted to a given casting, in relation to the size of the casting and/or in relation to the number of hot spots in the casting. Preferably, for the needs of this invention, liquefied gases, preferably liquefied nitrogen or other liquids with high heat accumulation capacity, are used as an agent flowing through the channels of the cooling plate.

The following is assumed for each shape of the casting: velocity, pressure, and temperature of the flow of the cooling agent as well as the velocity, pressure, and temperature of the agent discharged from the nozzles installed in the ports of the cooling element. The advantage of the cooling plate according to the invention is the acceleration of the process of solidification and cooling of the casting in sand moulds and in ceramic moulds, in particular in the areas of hot spots. The castings obtained by the acceleration of the solidification process with the possibility to control it are of high quality, and they are practically free of any casting defects. Moreover, the cooling of hot spots in the areas of the castings in which the use of feedheads is impossible for technological reasons is performed with a good result by the use of the cooling plate. In sand moulds, the casting is cooled evenly and under control, mechanical properties of the casting material are improved, and heat treatment of the casting is eliminated or significantly limited. The cooling plate according to the invention, depending on its size and the size of the mould, enables control over the casting cooling in one or several casting moulds at the same time. After being knocked out of the mould, the castings that have been cooled in a manner that was controlled by the cooling plate according to the invention are free of any shrinkage defects.

In the example of execution, the present invention was presented in the figure where Fig. 1 presents the top view of the cooling plate and its section with nozzles of different height and different direction of the cooling agent stream, Fig. 2A presents the cross section of the sand mould placed on the cooling plate equipped with nozzles of different height and mounted at the mould feeding station, Fig. 2B presents the top view of the mould and the cooling plate with marked internal channels, Fig. 3A presents the cross section of the sand mould with a casting round in shape, the mould of which is placed on the cooling plate equipped with nozzles with different stream directions, Fig. 3B presents the top view of the mould with marked shape of the casted element and the path of channels in the cooling plate.

A model cooling plate 7 is flat in shape with a rectangular base, in the body of which there is a hollow channel 12 in the shape of a double coil through which the cooling agent flows. Between the channel 12 there is a channel 13 through which the cooling agent with a lower temperature flows. Along the path of the channel 12 there are ports in which slot nozzles 11 and/or straight nozzles 8 and/or nozzles with an adjusted flow direction 9 and/or multipoint nozzles 10 are installed. Under the bottom of the sand mould 1 mounted on the cooling plate. 7, between the bottom of the mould 1 and the upper surface of the cooling plate 7, there is a cooling agent flow chamber 5. The cooling plate 7 is mounted at the casting station, where under the bottom of the cooling plate 7 there is a chamber through which the agent cooling the bottom surface of the cooling plate 7 flows. Between the cooling plate 7 and the bottom of the casting 2 there is a separating layer 3 of the sand mould 1, to the inside of which, to sand channels 4 the nozzles 8, 9, and 10 are inserted.

Claims

The cooling plate for the material casted in casting moulds, which is flat in shape, inside of which there are tubular elements in the shape of a coil through which air flows, characterised in that the flat shape of the plate has the base in any shape and the cooling plate (7) has the body inside which there is a hollow channel (12) with the path of any shape or channels (12) in the shape of a double coil and/or spiral and/or bored along or across the cooling plate (7), and between the channel (12) there is the channel (13), and along the path of the channel (12) on the interface between the cooling plate (7) and the separating layer (3) there are ports in which nozzles of different structure are mounted.

The plate according to claim 1, characterised in that to the ports in the channels (12) of the cooling plate (7) the slot nozzles (11) and/or straight nozzles (8) and/or nozzles with an adjusted flow direction (9) and/or multipoint nozzles (10) are mounted.

The plate according to claim 1 characterised in that under the bottom of the sand mould (1) mounted on the cooling plate (7) between the bottom of the mould (1) and the upper surface of the cooling plate (7) , there is a cooling agent flow chamber (5) . The plate according to claim 1 characterised in that it is mounted at the casting station, where under the bottom of the cooling plate (7) there is a chamber through which the agent cooling the bottom surface of the cooling plate (7) flows .

The plate according to claim 1 characterised in that between the cooling plate (7) and the bottom of the casting (2) there is a separating layer (3) of the sand mould (1) inside which, in the channels (4) there are straight nozzles (8), nozzles with an adjusted flow direction (9) and multipoint nozzles (10) are placed.