Patent Application
20170037852
Pumps for pumping molten metal are used in furnaces in the production of metal articles. Common functions of pumps are circulation of molten metal in the furnace or transfer of molten metal to remote locations along transfer conduits or risers that extend from a base of the pump to the remote location.
Currently, many metal die casting facilities employ a main hearth containing the majority of the molten metal. Solid bars of metal may be periodically melted in the main hearth. A transfer pump is located in a separate well adjacent the main hearth. The transfer pump draws molten metal from the well in which it resides and transfers it into a ladle or conduit and from there to die casters that form the metal articles. The present invention relates to pumps used to transfer molten metal from a furnace to a die casting machine, ingot mould, DC caster or the like.
A traditional molten metal transfer pump is described in U.S. Pat. No. 6,286,163, the disclosure of which is herein incorporated by reference. Referring to
Another exemplary transfer pump is described in CA 2284985. The pump consists of two main parts, an upper tube portion which is suspended above the molten magnesium bath during operation and lower tube portion which is immersed in the bath. A motor is positioned at the top of the upper portion. A coupling attaches an auger shaft to the motor. The coupling holds the weight of the auger shaft and positions it in place inside the tube. The auger shaft is centered within the internal diameter of the two portions, running the length of both, and is held in position by a set of guide bearings. The lower portion is comprised of a cylindrical casing in which the auger is located and aligned. Several inlet holes are located in the walls of the cylindrical casing. A second set of inlet holes in the cylindrical casing are located near the base of the pump. These inlet holes permit the surrounding molten metal to enter the pump.
The auger comprises a shaft, upon which are welded flutes. The pitch of the flutes preferably varies between 2 to 4 inches. The auger acts like a positive displacement pump. The rotation of the auger shaft by the motor supplies a steady force to the molten magnesium, forcing the molten liquid to the bottom of the pump and out of an elbow shaped connector located at the outlet end of the cylindrical casing at the base of the pump. The molten magnesium displaced to the bottom of the pump is downwardly forced out through the connector by means of the rotation of the auger. The connector is attached to a heated transfer tube which will convey the molten magnesium from the holding furnace to the die of a casting machine.
A further alternative transfer pump is described in U.S. Published Application 2008/0314548. The system comprises at least (1) a vessel for retaining molten metal, (2) a dividing wall (or overflow wall) within the vessel, the dividing wall having a height H1 and dividing the vessel into a least a first chamber and a second chamber, and (3) a molten metal pump in the vessel, preferably in the first chamber. The second chamber has a wall or opening with a height H2 that is lower than height H1 and the second chamber is juxtaposed another structure, such as a ladle or lauder, into which it is desired to transfer molten metal from the vessel. The pump (either a transfer, circulation or gas-release pump) is submerged in the first chamber (preferably) and pumps molten metal from the first chamber past the dividing wall and into the second chamber causing the level of molten metal in the second chamber to rise. When the level of molten metal in the second chamber exceeds height H2, molten metal flows out of the second chamber and into another structure. If a circulation pump, which is most preferred, or a gas-release pump were utilized, the molten metal would be pumped through the pump discharge and through an opening in the dividing wall wherein the opening is preferably completely below the surface of the molten metal in the first chamber.
Various details of the present disclosure are hereinafter summarized to provide a basic understanding. This summary is not an extensive overview of the disclosure, and is intended neither to identify certain elements of the disclosure, nor to delineate the scope thereof. Rather, the primary purpose of this summary is to present some concepts of the disclosure in a simplified form prior to the more detailed description that is presented hereinafter.
According to one embodiment of this disclosure, a molten metal pump comprising an elongated tube having a base end and a top end is provided. A shaft extends into the tube and rotates an impeller proximate the base end. The tube has a diameter at least 1.1 times the diameter of the impeller. The tube has a length at least three times the height of the impeller. The base end includes an inlet and the top end includes an outlet.
According to an alternative embodiment, a molten metal pump comprised of an elongated refractory body is provided. The refractory body includes an inlet region having an inlet region diameter, a vortex region having a vortex region diameter, and an outlet region having an outlet region diameter. The outlet region diameter is greater than the vortex region diameter which is greater than the inlet region diameter. An impeller is disposed in or adjacent the inlet. A shaft extends through the vortex region and the outlet region and includes a first end engaging the impeller and a second end adapted to engage a motor.
The following description and drawings set forth certain illustrative implementations of the disclosure in detail, which are indicative of several exemplary ways in which the various principles of the disclosure may be carried out. The illustrated examples, however, are not exhaustive of the many possible embodiments of the disclosure. Other objects, advantages and novel features of the disclosure will be set forth in the following detail description of the disclosure when considered in conjunction with the drawings, in which:
One or more embodiments or implementations are hereinafter described in conjunction with the drawings, where like reference numerals are used to refer like elements throughout, and where the various features are not necessary drawn to scale.
With reference to
Although depicted as a volute cavity, an alternative mechanism could be utilized to divert the rotating molten metal vortex into the trough. In fact, a tangential outlet extending from even a cylindrical cavity will achieve molten metal flow. However, a diverter such as a wing extending into the flow pattern or other element which directs the molten metal into the trough may be preferred.
In addition, in certain environments, it may be desirable to form the base of the tube into a general bell shape, rather than flat. This design may produce a deeper vortex and allow the device to have improved function as a scrap submergence unit.
Turning now to
Referring now to
Referring now to
Referring now to
The invention has many advantages in that its design creates an equilibrium vortex at a low impeller RPM, creating a smooth surface with lithe to no air intake. Accordingly, the vortex is non-violent and creates little or no dross. Moreover, the present pump creates a forced vortex having a constant angular velocity such that the column of rotating molten metal rotates as a solid body having very lithe turbulence.
Other advantages include the elimination of the riser component in traditional molten metal pumps which can be fragile and prone to clogging and damage. In addition, the design provides a very small footprint relative to the traditional transfer pump base and has the ability to locate the impeller very close to the bay bottom, allowing for very low metal draw down. As a result of the small footprint, The device is suitable for current refractory furnace designs and will not require significant modification thereto.
The pump has excellent flow tunability, its open design structure provides for simple and easily cleaning access. Advantageously, only shaft and impeller replacement parts will generally be required. In fact is generally self-cleaning wherein dross formation in the riser is eliminated because the metal level is high. Generally, a lower torque motor, such as an air motor, will be sufficient because of the low torque experienced.
Optional additions to the design include the location of a filter at the base of the inlet of the pumping chamber. It is further envisioned that the pump would be suitable for use in molten zinc environments where a very long, pull (e.g. 14 ft.) is required. Such a design may preferably include the addition of a bearing mechanism at a location on the rotating shaft intermediate the motor and impeller. Furthermore, in a zinc application, the entire construction could be manufactured from metal, such as steel or stainless steel, including the pumping chamber tube, and optionally the shaft and impeller.
The exemplary embodiment has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
| Number | Date | Country | |
|---|---|---|---|
| 61187457 | Jun 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13378078 | Jun 2012 | US |
| Child | 15298349 | US |
