Patent Application
20140174143
The present invention relates generally to extrusion and in particular, to an extrusion press container and a mantle for same.
Metal extrusion presses are well known in the art, and are used for forming extruded metal products having cross-sectional shapes that generally conform to the shape of the extrusion dies used. A typical metal extrusion press comprises a generally cylindrical container having an outer mantle and an inner tubular liner. The container serves as a temperature controlled enclosure for a billet during extrusion. An extrusion ram is positioned adjacent one end of the container. The end of the extrusion ram abuts a dummy block, which in turn abuts the billet allowing the billet to be advanced through the container. An extrusion die is positioned adjacent the opposite end of the container.
During operation, once the billet is heated to a desired extrusion temperature (typically 800-900° F. for aluminum), it is delivered to the extrusion press. The extrusion ram is then activated to abut the dummy block thereby advancing the billet into the container and towards the extrusion die. Under the pressure exerted by the advancing extrusion ram and dummy block, the billet is extruded through the profile provided in the extrusion die until all or most of the billet material is pushed out of the container, resulting in the extruded product.
In order to attain cost-saving efficiency and productivity in metal extrusion technologies, it is important to achieve thermal alignment of the extrusion press. Thermal alignment is generally defined as the control and maintenance of optimal running temperature of the various extrusion press components. Achieving thermal alignment during production of extruded product ensures that the flow of the extrudable material is uniform, and enables the extrusion press operator to press at a higher speed with less waste.
As will be appreciated, optimal billet temperature can only be maintained if the container can immediately correct any change in the liner temperature during the extrusion process, when and where it occurs. Often all that is required is the addition of relatively small amounts of heat to areas that are deficient.
A number of factors must be considered when assessing the thermal alignment of an extrusion press. For example, the whole of the billet of extrudable material must be at the optimum operating temperature in order to assure uniform flow rates over the cross-sectional area of the billet. The temperature of the liner in the container must also serve to maintain, and not interfere with, the temperature profile of the billet passing therethrough.
Achieving thermal alignment is generally a challenge to an extrusion press operator. During extrusion, the top of the container usually becomes hotter than the bottom. Although conduction is the principal method of heat transfer within the container, radiant heat lost from the bottom surface of the container rises inside the container housing, leading to an increase in temperature at the top. As the front and rear ends of the container are generally exposed, they will lose more heat than the center section of the container. This may result in the center section of the container being hotter than the ends. As well, the temperature at the extrusion die end of the container tends to be slightly higher compared to the ram end, as the billet heats it for a longer period of time. These temperature variations in the container affect the temperature profile of the liner contained therein, which in turn affects the temperature of the billet of extrudable material. The temperature profile of the extrusion die generally conforms to the temperature profile of the liner, and the temperature of the extrusion die affects the flow rate of extrudable material therethrough. Although the average flow rate of extrudable material through the extrusion die is governed by the speed of the ram, flow rates from hotter sections of the billet will be faster compared to cooler sections of the billet. The run-out variance across the cross-sectional profile of a billet can be as great as 1% for every 5° C. difference in temperature. This can adversely affect the shape of the profile of the extruded product. Control of the temperature profiles of the liner and of the container is therefore of great importance to the efficient operation of the extrusion process.
One approach to achieving such temperature profile control of the liner and the container involves introducing cooling to the container. Cooling in extrusion press containers has been previously described. For example, U.S. Pat. No. 5,678,442 to Ohba et al. discloses an extruder having a cylindrical container into which a billet is loaded; a two-piece seal block disposed on an end surface of the container at an extruding stem side; a vacuum deaerating hole formed in the seal block; and a fixed dummy block, having an internal cooling function, fixed to an end of the extruding stem, wherein the seal block is allowed to be opened and closed in a direction perpendicular to the axial direction of the container and the seal block comes in close contact with an outer surface of the extruding stem and the end surface of the container when the seal block is closed.
U.S. Pat. No. 4,829,802 to Baumann discloses an apparatus comprising a region of an extrusion chamber immediately ahead of an extrusion die that is cooled by placing a cooling ring between the bore of an extrusion cylinder in which a ram piston operates. The cooling ring may be a unitary structure, or a multi-part structure, in which an independent inner ring is located within the cooling ring. For mechanical strength, a prestressing outer ring is shrink-fitted around the cooling ring. The outer ring is retained, for example by screws, on a cylinder within which the extrusion chamber is located. The cooling fluid may be water, a vaporizable liquid, or a gas, and is separated from the billet within the extrusion chamber.
Improvements are generally desired. It is therefore an object at least to provide a novel extrusion press container and a mantle for same.
In one aspect, there is provided a container for use in a metal extrusion press, the container comprising: a mantle having an elongate body comprising an axial bore; an elongate liner accommodated within the axial bore, the liner comprising a longitudinally extending passage through which a billet is advanced; and a fluid channel in thermal communication with the mantle through which a fluid for cooling the container flows.
The fluid channel may comprise at least one groove formed in the outer surface of the mantle. The at least one groove may be a serpentine groove. The mantle may have a generally cylindrical shape, and at least a portion of the at least one groove may extend in a circumferential direction. The fluid channel may further comprise a cover plate covering the at least one groove.
The container may further comprise a fluid guide configured for one or more of: directing fluid into the fluid channel, and directing fluid out of the fluid channel.
The fluid channel may be adjacent a die end of the container. The fluid channel may be adjacent an upper portion of the container.
The fluid may be a gas. The gas may be air.
The mantle may be configured for connecting to an extrusion press.
In another aspect, there is provided a mantle for an extrusion press container, the mantle comprising: an elongate body comprising an axial bore for accommodating a liner through which a billet is advanced, the body having a fluid channel in thermal communication therewith through which a fluid for cooling the container flows.
The fluid channel may comprise at least one groove formed in an outer surface of the mantle. The at least one groove may be a serpentine groove. The mantle may have a generally cylindrical shape, and at least a portion of the at least one groove may extend in a circumferential direction. The mantle may be configured to receive a cover plate for covering the at least one groove. The at least one groove may be adjacent a die end of the mantle. The at least one groove may be formed in an upper portion of the mantle. The mantle may be configured to have a fluid guide mounted thereto, the fluid guide being configured for one or more of: directing fluid into the fluid channel, and directing fluid out of the fluid channel.
In another aspect, there is provided a method of controlling temperature of a container of a metal extrusion press, comprising: flowing fluid through a fluid channel that is in thermal communication with a mantle of the container for cooling the container; and controlling flow rate of the fluid to adjust the temperature of the container.
The method may further comprise controlling thermal energy supplied by at least one heating element accommodated within the mantle.
Embodiments will now be described more fully with reference to the accompanying drawings in which:
a and 6b are side sectional views of a mantle forming part of the container of
a to 8c are rear perspective, rear elevational, and top sectional views, respectively, of a fluid guide forming part of the container of
During operation, once the billet 26 is heated to a desired extrusion temperature (typically 800-900° F. for aluminum), it is delivered to the extrusion press. The extrusion ram 28 is then actuated to abut the dummy block 30, thereby to advance the billet 26 into the container and towards the extrusion die 32. Under the pressure exerted by the advancing extrusion ram 28 and dummy block 30, the billet 26 is extruded through the profile provided in the extrusion die 32 until all or most of the billet material is pushed out of the container 20, resulting in the extruded product 34.
The container 20 may be better seen in
The mantle 22 also comprises a plurality of longitudinal bores 38 extending from the ram end 40 of the mantle 22 to the die end 36 of the mantle 22, and surrounding the liner 24. Each longitudinal bore 38 is shaped to accommodate an elongate heating element, described further below, that can be energized to provide thermal energy to the mantle 22 in the vicinity of the liner 24 during use. The number of longitudinal bores 38 needed depends on the size of the container 20 and on the voltage used to energize the elongate heating elements. In this embodiment, the mantle comprises 22 ten (10) longitudinal bores 38. In the embodiment shown, the container 20 has an end cover plate installed 41 on its die end 36 that covers the ends of the longitudinal bores 38.
The mantle 22 further comprises a plurality of bores 42 and 44 adjacent the liner 24 and extending partially into the length of the mantle 22. In this embodiment, the mantle 22 comprises two (2) bores 42 extending from the die end 36 approximately four (4) inches into the mantle 22, and two (2) bores 44 extending from the ram end 40 approximately four (4) inches into the mantle 22. Each bore 42 and 44 is shaped to accommodate a temperature sensor (not shown). The bores 42 and 44 are positioned in a manner so as to avoid intersecting any of the longitudinal bores 38 configured for accommodating the heating elements. In this embodiment, one (1) of the bores 42 is positioned above the liner 24 while the other bore 42 is positioned below the liner 24, and one (1) of the bores 44 is positioned above the liner 24 while the other bore 44 is positioned below the liner 24.
The liner 24 comprises a billet receiving passage 46 that extends longitudinally therethrough and, in the embodiment shown, the passage 46 has a generally circular cross-sectional profile.
The container 20 also comprises a heat sink that is in thermal communication with the mantle, and which is configured for cooling the container 20. In this embodiment, the heat sink comprises a fluid channel 50 adjacent an upper surface of the container 20 at the die end 36. The fluid channel 50 comprises a circumferentially-oriented, serpentine groove 52 formed in an upper portion of the outer surface of the mantle 22, and a cover plate 54 that is sized to cover the groove 52. When the cover plate 54 is installed so as to cover the groove 52, the fluid channel 50 provides a generally enclosed, continuous channel through which fluid may flow to cool the container 20.
The fluid channel 50 is in fluid communication with a supply of pressurized fluid via an elongate fluid guide 60 accommodated within a longitudinal groove 61 that extends along a side of the mantle 22. The fluid guide 60 comprises an input port 62 that is in fluid communication with a first end 64 of the fluid channel 50, and that is also in fluid communication with a supply of pressurized fluid (not shown) via a supply line (not shown). In this embodiment, the fluid is air. A flow rate control apparatus (not shown) is connected to the supply of pressurized fluid and/or the supply line, and is configured to allow the flow rate of fluid entering the input port 62 to be controlled by an operator. The fluid guide 60 also comprises an output port 66 that is in fluid communication with a second end 68 of the fluid channel 50, and which is also in fluid communication with an exhaust line (not shown).
Each temperature sensor (not shown) is configured to monitor the temperature of the container during operation. The positioning of the two (2) bores 42 enables one (1) temperature sensor to be placed in the upper die end zone 72d, and one (1) temperature sensor to be placed in the lower die end zone 72c. Similarly, the positioning of the two (2) bores 44 enables one (1) temperature sensor to be placed in the upper ram end zone 72f, and one (1) temperature sensor to be placed in the lower ram end zone 72e. In this embodiment, the sensing elements are thermocouples. The temperature sensors feed into the controller, providing the operator with temperature data from which subsequent temperature adjustments can be made. As will be appreciated, the positioning of temperature sensors in the mantle 22 both above and below the liner 24 advantageously allows the vertical temperature profile across the liner 24 to be measured, and moreover allows any vertical temperature difference that arises during extrusion to be monitored by the operator.
During operation, temperature data output from the temperature sensors is monitored by the operator. The position of the fluid channel 50 advantageously allows any temperature increase within the upper die end zone 72d to be reduced or eliminated by increasing the fluid flow rate therethrough. As will be understood, fluid provided by the pressurized fluid supply line enters the first end 64 of the fluid channel 50 via the input port 62 of the fluid guide 60. As the fluid travels along the length of fluid channel 50 to the second end 68, heat is transferred from the mantle 22 to the flowing fluid. The fluid exits from the fluid channel 50 via the output port 66 and enters the exhaust line. As will be appreciated, the transfer of heat from the mantle 22 to the flowing fluid results in a temperature reduction within the upper die end zone 72d of the container 20.
Additionally, the positioning of the elongate heating elements also advantageously allows any temperature increase within the upper die end zone 72d to be reduced or eliminated by reducing the thermal energy supplied by heating elements 70 positioned above the liner 24. Thus, as each of the heating elements are individually controllable, and as the flow rate of fluid through the fluid channel 50 is also controllable, the thermal profile across the liner 24 and within the container 20 can be accurately controlled. As will be understood, one or both of control of the fluid flow rate through the fluid channel 50, and control of the thermal energy supplied the heating elements, may be used to control the thermal profile across the liner 24 and within the container 20.
It will be understood that the liner is not limited to the configuration described above, and in other embodiments, the liner may alternatively have other configurations. For example, the liner may alternatively comprise a billet receiving passage having a generally rectangular cross-sectional profile that may comprise any of flared ends, rounded corners, and rounded sides, as described in U.S. Application Publication No. 2013/0074568, filed Sep. 17, 2012, entitled “EXTRUSION PRESS CONTAINER AND LINER FOR SAME”, the content of which is incorporated by reference herein in its entirety.
Although in the embodiment described above, the fluid channel comprises a circumferentially-oriented, serpentine groove formed in the upper portion of the outer surface of the mantle, in other embodiments, the groove may have other configurations. For example, in other embodiments, the fluid channel may alternatively comprise a longitudinally-oriented, serpentine groove formed in the upper portion of the outer surface of the mantle. Those skilled in the art will understand that still other groove configurations are possible. Additionally, the groove need not necessarily be serpentine, and in other embodiments, the groove may alternatively have a non-serpentine configuration.
Although in the embodiment described above, the longitudinal bores for the elongate heating elements extend the length of the mantle, in other embodiments, the longitudinal bores for the elongate heating elements may alternatively extend only partially the length of the mantle. For example, in one embodiment, the longitudinal bores may alternatively extend from the ram end of the mantle to approximately one-half (0.5) inches from the die end of the mantle.
Although in the embodiment described above, the elongate heating elements are configured with die end heating sections and ram end heating sections, in other embodiments, the elongate heating elements may alternatively be configured with additional or fewer heating sections, and/or may alternatively be configured to heat along the entire length of the heating cartridge.
Although in the embodiment described above, the elongate heating elements in the vicinity of the lower die end zone and the lower ram end zone are described as being configured to be controlled by the operator to provide added temperature, it will be understood that these elongate heating elements are also configured to be controlled by the operator to provide reduced temperature. Similarly, although in the embodiment described above, the elongate heating elements in the vicinity of the upper die end zone and the upper ram end zone are described as being configured to be controlled by the operator to provide reduced temperature, it will be understood that these elongate heating elements are also configured to be controlled by the operator to provide added temperature.
Although in the embodiment described above, the mantle comprises four (4) bores for accommodating temperature sensors, in other embodiments, the mantle may alternatively comprise additional or fewer bores for accommodating temperature sensors.
Although in the embodiment described above, the bores for accommodating temperature sensors extend partially into the length of the mantle, in other embodiments, the bores may alternatively extend the full length of the mantle. In related embodiments, the temperature sensors may alternatively be “cartridge” type temperature sensors, and may alternatively comprise a plurality of temperature sensing elements positioned along their length.
Although in the embodiment described above, the fluid is air, in other embodiments, one or more other suitable fluids may alternatively be used. For example, in other embodiments, the fluid may be any of nitrogen and helium. In other embodiments, the fluid may be cooled by a cooling apparatus prior to entering the fluid channel.
Although in the embodiment described above, the fluid channel comprises a groove formed in an upper portion of the outer surface of the mantle, in other embodiments, other configurations in which the fluid channel is in thermal communication with the mantle are possible. For example, in other embodiments, the fluid channel may alternatively comprise a groove formed in one or more other portions of the outer surface of the mantle. In still other embodiments, the fluid channel may alternatively comprise a fluid channel passing through the interior of the mantle.
Although embodiments have been described above with reference to the accompanying drawings, those of skill in the art will appreciate that variations and modifications may be made without departing from the scope thereof as defined by the appended claims.
This application claims the benefit of provisional U.S. application Ser. No. 61/745,121 filed on Dec. 21, 2012, the content of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61745121 | Dec 2012 | US |
