Patent Application
20220241847
In a sand casting process, an expendable mold package is assembled from a plurality of resin-bonded sand cores that define internal and external surfaces of a device, wherein each of the sand cores may be formed by blowing resin-coated foundry sand into a core box and curing it therein. One example includes a sand casting process for an internal combustion engine block.
In one embodiment, the mold assembly method involves positioning a base core on a surface and building up or stacking separate mold elements to shape such casting features. When casting an internal combustion engine block, elements may include sides, ends, valleys, water jackets, cam openings, and a crankcase of the cylinder block, with additional cores being present depending on the engine design.
Removal of thermal energy from liquified metal in a mold package is an important consideration in the foundry process. Rapid solidification and cooling of the cast device promotes a fine grain structure in the solidified metal, leading to desirable material properties including high tensile strength, high fatigue strength, and good machinability. By way of a non-limiting example, dendrites may be formed during solidification of the liquified metal when the liquified metal is an aluminum alloy. The length, orientation, and configuration of the dendrites may affect structural and material properties of the cast device. Excess dendrite lengths, orientations, and configurations may negatively affect tensile strength and fatigue strength, thus affecting the service life of the cast device. Achieving smaller DAS (Dendrite arm spacing) in a sand cast block may be challenging in certain locations, such as near vent windows and cam bore regions of an engine block.
As such, there is a need for improved cooling of a cast device during solidification of the liquified metal in order to reduce DAS and porosity particularly in the high-stressed bulkhead areas. Furthermore, it is desirable to produce a cylinder block cast device in a manner that enhances material mechanical properties in the bulkhead area, increases casting efficiency, and improves casting accuracy.
The concepts provided herein provide a profiled chill for improved cooling of a cast device during solidification of liquid metal. The improved cooling afforded by the profiled chill refines the cast aluminum microstructure by improving cooling during solidification of the liquid metal. The improvement to quickly cooling liquid metal during solidification refines the cast aluminum microstructure by decreasing Dendrite Arm Spacing (DAS) and reducing porosity, resulting in improved mechanical properties in-use.
When the cast device is an engine block for an internal combustion engine, the profiled chill may be employed to improve material properties in a bulkhead area. The profiled chill is much more thermally conductive than foundry sand to conduct heat from portions of the cast device. The profiled chill includes one or more thermo-conductive elements that are assembled in a mold in a manner to shape some portion of the features of the cast device. The profiled chill may be placed into base core tooling with a base core formed about it, or it may be assembled into the base core during mold assembly.
An aspect of the disclosure includes a mold package for casting an engine block, wherein the mold package includes a profiled chill and a mold core assembly that is disposed on the profiled chill. The mold core assembly defines a plurality of bulkheads of the engine block. The profiled chill includes a first chill portion having a second chill portion and a plurality of third chill portions arranged thereon, wherein the second chill portion is a semicylindrical element. The third chill portions are arranged to be adjacent to the plurality of bulkheads of the engine block.
Another aspect of the disclosure includes the first chill portion being arranged as a rectangular prism, and wherein the semicylindrical element of the second chill portion is arranged on a surface of the first chill portion.
Another aspect of the disclosure includes the semicylindrical element of the second chill portion being adjacent to saddle regions of the plurality of bulkheads of the engine block.
Another aspect of the disclosure includes a front bulkhead, a rear bulkhead, and a plurality of intermediate bulkheads, wherein the plurality of third chill portions includes one of the third chill portions being arranged adjacent to an inner side portion of the front bulkhead, one of the third chill portions being arranged adjacent to an inner side portion of the rear bulkhead, and paired sets of the third chill portions being arranged adjacent to first and second side portions of each of the plurality of intermediate bulkheads.
Another aspect of the disclosure includes each of the plurality of bulkheads having an end portion, wherein the first chill portion is adjacent to the end portions of the plurality of bulkheads of the engine block.
Another aspect of the disclosure includes a front bulkhead, a rear bulkhead, and a plurality of intermediate bulkheads, wherein each includes a saddle portion, an end portion, and side portions, and wherein the first chill portion is arranged as a rectangular prism, wherein the semicylindrical element of the second chill portion is arranged on a surface of the first chill portion, and wherein the third chill portion is arranged on the semicylindrical element of the second chill portion.
Another aspect of the disclosure includes the semicylindrical element of the second chill portion being arranged adjacent to the saddle portion of each of the plurality of bulkheads of the engine block.
Another aspect of the disclosure includes the plurality of third chill portions being arranged adjacent to the sides of the plurality of bulkheads of the engine block.
Another aspect of the disclosure includes one of the third chill portions being disposed adjacent to an inner side portion of the front bulkhead, one of the third chill portions being disposed adjacent to an inner side portion of the rear bulkhead, and paired sets of the third chill portions being disposed adjacent to first and second side portions of each of the plurality of intermediate bulkheads.
Another aspect of the disclosure includes the first chill portion being disposed adjacent to the end portions of the plurality of bulkheads of the engine block.
Another aspect of the disclosure includes the profiled chill being disposed on a profiled chill plate.
Another aspect of the disclosure includes the profiled chill being fabricated from a thermally conductive material.
Another aspect of the disclosure includes the thermally conductive material being one of copper alloy, an aluminum alloy, a steel alloy, or an iron alloy.
Another aspect of the disclosure includes the first, second and third chill portions being fabricated from a solid material.
Another aspect of the disclosure includes the first, second and third chill portions including an internal fluidic passage for accommodating a coolant fluid.
Another aspect of the disclosure includes a profiled chill for a mold package that is configured for casting a device having an interior bulkhead. The profiled chill includes a first chill portion having a second chill portion and a plurality of third chill portions arranged thereon. The first chill portion is a rectangular prism including a first surface, the second chill portion is a semicylindrical element that is arranged on the first surface of the first chill portion, and the plurality of third chill portions are arranged on the first chill portion and extend from the semicylindrical element of the second chill portion. The third chill portions are arranged to be adjacent to the interior bulkhead of the device.
The above summary is not intended to represent every possible embodiment or every aspect of the present disclosure. Rather, the foregoing summary is intended to exemplify some of the novel aspects and features disclosed herein. The above features and advantages, and other features and advantages of the present disclosure, will be readily apparent from the following detailed description of representative embodiments and modes for carrying out the present disclosure when taken in connection with the accompanying drawings and the claims.
One or more embodiments will now be described, by way of example, with reference to the accompanying drawings, in which:
The appended drawings are not necessarily to scale and may present a somewhat simplified representation of various preferred features of the present disclosure as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes. Details associated with such features will be determined in part by the particular intended application and use environment.
The components of the disclosed embodiments, as described and illustrated herein, may be arranged and designed in a variety of different configurations. Thus, the following detailed description is not intended to limit the scope of the disclosure, as claimed, but is merely representative of possible embodiments thereof. In addition, while numerous specific details are set forth in the following description in order to provide a thorough understanding of the embodiments disclosed herein, some embodiments can be practiced without some of these details. Moreover, for the purpose of clarity, certain technical material that is understood in the related art has not been described in detail in order to avoid unnecessarily obscuring the disclosure. For purposes of convenience and clarity, directional terms such as top, bottom, left, right, up, over, above, below, beneath, rear, and front, may be used with respect to the drawings. These and similar directional terms are not to be construed to limit the scope of the disclosure. The disclosure, as illustrated and described herein, may be practiced in the absence of an element that is not specifically disclosed herein. Furthermore, there is no intention to be bound by an expressed or implied theory presented herein. Corresponding reference numerals indicate like or corresponding parts and features throughout the drawings.
Referring to the drawings,
Referring again to
To form the engine block 10, a mold core assembly is formed onto the profiled chill 50 and the mold gate arrangement 92 within the engine block mold package 100. The mold core assembly includes, e.g., a crankcase core, end cores, side cores, water jacket slab core assemblies, a tappet valley core, and a cover core. The profiled chill 50 and the mold core assembly shape portions of the features of the cast device, including shaping the plurality of bulkheads. Liquid metal is poured into the engine block mold package 100 and cooled to form the cast device.
Referring again to
The first chill portion 52 is arranged as a rectangular prism having a top surface 54 and the bottom surface 56, previously shown with reference to
The second chill portion 60 is a semicylindrical element with a curved surface 62 in the xz-plane and is arranged on the top surface 54 of the first chill portion 52. The curved surface 62 of the semicylindrical element of the second chill portion 60 is adjacent to a plurality of saddle regions 26 of the plurality of bulkheads that are formed in the engine block 10 during casting. The saddle regions 26 are semi-cylindrical portions on which an engine crankshaft and associated bearings are assembled.
The plurality of third chill portions 64 are arranged on the top surface 54 of the first chill portion 52 on top of the second chill portion 60 and are arranged longitudinally to be adjacent to the plurality of bulkheads of the engine block 10. Each of the third chill portions 64 has a quasi-triangular shape in the xz-plane, including a flattened tip 65.
The profiled chill 50 with the first chill portion 52, the second chill portion 60 and the plurality of third chill portions 64 may be an assembly of components or may be formed as a unitary device with features as described herein.
The profiled chill 50 is advantageously fabricated from a thermally conductive material, such as an iron alloy, a steel alloy, a copper alloy, an aluminum alloy etc. In one embodiment, the profiled chill 50 is fabricated from a solid mass of material. Alternatively, one or more of the first, second and third chill portions may include an internal fluidic passage 58 that is capable of accommodating a circulating coolant.
Referring again to
Referring again to
Referring again to
The plurality of the third chill portions 64 are arranged as follows. One of the third chill portions 64 is arranged to be adjacent to an inner side portion 14 of the front bulkhead 12. One of the third chill portions 64 is arranged to be adjacent to an inner side portion 18 of the rear bulkhead 16. Paired sets of the third chill portions 64 are arranged to be adjacent to first and second side portions 21, 22, respectively, of each of the plurality of intermediate bulkheads 20.
The concepts described herein provide a profiled chill 50, such as is described with reference to
The profiled chill 50 provides improved cooling during solidification at the locations near to vent windows/holes and around the cam bore regions in the bulkhead, as compared to present chill. This serves to refine the cast aluminum microstructure by decreasing cast aluminum Dendrite Arm Spacing (DAS) and reducing porosity, resulting in improved mechanical properties in-use.
The detailed description and the drawings or figures are supportive and descriptive of the present teachings, but the scope of the present teachings is defined solely by the claims. While some of the best modes and other embodiments for carrying out the present teachings have been described in detail, various alternative designs and embodiments exist for practicing the present teachings defined in the claims.
