Patent Application
20180029109
Aspects described herein generally relate to the side frames for railway trucks and fabrication of side frames. More specifically, aspects relate to center core construction and implementation in the fabrication of railway truck side frames.
Railway cars typically consist of a rail car that rests upon a pair of truck assemblies. The truck assemblies include a pair of side frames and wheelsets connected together via a bolster and damping system. The car rests upon the center bowl of the bolster, which acts as a point of rotation for the truck system. The car body movements are reacted through the springs and friction wedge dampers, which connect the bolster and side frames. The side frames include pedestals that each define a jaw into which a wheel assembly of a wheel set is positioned using a roller bearing adapter. Additionally, the side frames include bolster openings through which the bolster, and the springs and friction wedge dampers attached thereto, are assembled into.
The side frames may be formed via various casting techniques. The most common technique for producing these components is through sand casting. Sand casting offers a low cost, high production method for forming complex hollow shapes such as a side frame. In a typical sand casting operation, (1) a mold is formed by packing sand around a pattern, which generally includes the gating system; (2) The pattern is removed from the mold; (3) cores, which may form the interior cavity or profile of the casting, may be formed separately and then placed into the mold, which is then closed; (4) the mold is filled with hot liquid metal through the gating; (5) the metal is allowed to cool in the mold; (6) the solidified metal referred to as raw casting is removed by breaking away the mold and/or sand mold cores; (7) and the casting is finished and cleaned which may include the use of grinders, welders, heat treatment, shot blasting, and machining.
In a sand casting operation, the mold is created using sand as a base material, mixed with a binder to retain the shape. The mold is created in two halves—cope (top) and drag (bottom) which are separated along the parting line. The sand is packed around the pattern and retains the shape of the pattern after the pattern is extracted from the mold. Draft angles of 3 degrees or more are machined into the pattern to ensure the pattern releases from the mold during extraction. In some sand casting operations, a flask is used to support the sand during the molding process through the pouring process.
The mold typically contains the gating system which provides a path for the molten metal, and controls the flow of metal into the cavity. This gating consists of a sprue, which controls metal flow velocity, and connects to the runners. The runners are channels for metal to flow through the gates into the cavity. The gates control flow rates into the cavity, and prevent turbulence of the liquid.
After the metal has been poured into the mold, the casting cools and shrinks as it approaches a solid state. As the metal shrinks, additional liquid metal must continue to feed the areas that contract, or voids will be present in the final part. In areas of high contraction, risers are placed in the mold to provide a secondary reservoir to be filled during pouring. These risers are the last areas to solidify, and thereby allow the contents to remain in the liquid state longer than the cavity of the part being cast. As the contents of the cavity cool, the risers feed the areas of contraction, ensuring a solid final casting is produced. Risers that are open on the top of the cope mold can also act as vents for gases to escape during pouring and cooling.
When casting a complex or hollow part, cores are used to define the hollow interior portions, or complex sections that cannot otherwise be created with the pattern. These cores are typically created by molding sand and binder in a box shaped as the feature being created with the core. These core boxes are either manually packed or created using a core blower. The cores are removed from the box, and placed into the mold. The cores are located in the mold using core prints to guide the placement, and prevent the core from shifting while the metal is poured. Additionally, chaplets may be used to support or restrain the movement of cores, and fuse into the base metal during solidification.
In side frame casting operations, multiple cores are used to aid in the formation of the structure of the frame. Traditionally, the mold of the side frame is fitted with a pair of pedestal & window cores, a lower tension member core, a pair of inner jaw cores, and a bolster core or bolster opening core including a spring seat core and a plurality of pin cores. The cores serve to provide structure in the formation of aspects of the frame including the bolster opening, compression member, spring seat, pedestal jaws, and so on.
While the usage of multiple cores is commonplace in side frame fabrication, the number of cores used increases the complexities of the manufacturing process, probability of manufacturing defects, and overall costs of production.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. The Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
Aspects of the disclosure are directed to center core construction and implementation in the fabrication of railway truck side frames. In certain examples a center core for manufacturing a side frame of a rail car, where the side frame includes a bolster opening configured to receive an outboard end of a bolster is disclosed. The center core may include a first side wall having an inside surface and an outside surface; a second side wall having an inside surface and an outside surface; a top wall having an inside surface and an outside surface; and a bottom wall having an inside surface and an outside surface; wherein the outside surfaces of the first side wall, the second side wall, the top wall and the bottom wall define the bolster opening; wherein the inside surfaces of the first side wall, the second side wall, the top wall and the bottom wall define at least one aperture; and wherein the first side wall includes at least one aperture configured to accept a pin core, and wherein the second side wall includes at least one aperture configured to accept a second pin core.
The center core may include a center column located between the first side wall and the second side wall. The center column may be substantially parallel with the first side wall and with the second side wall. The center column may be substantially centered between the first side wall and the second side wall.
The first side wall may include two apertures configured to accept the first pin core and a third pin core, and the second side wall may include two apertures configured to accept the second pin core and a fourth pin core.
In another example the disclosure provides a system for manufacturing a side frame of a rail car, where the side frame includes a bolster opening configured to receive an outboard end of a bolster. The system may include a center core comprising: a first side wall having an inside surface and an outside surface and having at least one aperture passing between the inside surface and the outside surface; a second side wall having an inside surface and an outside surface and having at least one aperture passing between the inside surface and the outside surface; a top wall having an inside surface and an outside surface; a bottom wall having an inside surface and an outside surface; at least a first pin core configured to engage the at least one aperture in the first side wall; and at least a second pin core configured to engage the at least one aperture in the second side wall. The outside surfaces of the first side wall, the second side wall, the top wall and the bottom wall may define the bolster opening; and the inside surfaces of the first side wall, the second side wall, the top wall and the bottom wall may define at least one hollow volume. Each of the first and second pin cores may also be engaged with a core adjacent to the center core.
The system may also include a center column located between the first side wall and the second side wall. The center column may be substantially parallel with the first side wall and with the second side wall. The center column may be substantially centered between the first side wall and the second side wall.
The system may also include a first aperture in the first side wall passing between the inside surface and the outside surface of the first side wall; a second aperture in the first side wall passing between the inside surface and the outside surface of the first side wall; a third aperture in the second side wall passing between the inside surface and the outside surface of the second side wall; a fourth aperture in the second side wall passing between the inside surface and the outside surface of the second side wall; a first pin core engaged with the first aperture; a second pin core engaged with the second aperture; a third pin core engaged with the third aperture; and a fourth pin core engaged with the fourth aperture.
The first and second pin cores may be substantially cylindrically shaped. The first and second pin cores may each include a center core engagement portion configured to engage the center core; a fastening hole portion configured to form a fastening hole in a finished side frame; and an adjacent core engagement portion configured to engage a core adjacent the center core.
The center core engagement portion and the adjacent core engagement portion may be substantially frustoconically shaped. The fastening hole portion may be substantially cylindrically shaped.
The first and second pin cores may each include at least one alignment feature. The alignment feature may include a first side ridge; a second side ridge; and a bottom ridge.
In another example, the disclosure provides, a method for manufacturing a side frame of a rail car, where the side frame includes a bolster opening configured to receive an outboard end of a bolster. The method includes providing a first portion of a mold; inserting a center core in the first portion of the mold, the center core comprising: a first side wall having an inside surface and an outside surface and having at least one aperture passing between the inside surface and the outside surface; a second side wall having an inside surface and an outside surface and having at least one aperture passing between the inside surface and the outside surface; a top wall having an inside surface and an outside surface; a bottom wall having an inside surface and an outside surface, wherein outside surfaces of the first side wall, the second side wall, the top wall and the bottom wall define the bolster opening; and wherein the inside surfaces of the first side wall, the second side wall, the top wall and the bottom wall define at least one hollow volume; inserting a first pin core through the at least one hollow volume into the at least one aperture in the first side wall and engaging the first pin core with a core adjacent to the center core; and inserting a second pin core through the at least one hollow volume into the at least one aperture in the second side wall and engaging the second pin core with a core adjacent to the center core.
The method may also include inserting a third pin core through the at least one hollow volume into a third aperture in the first side wall; and inserting a fourth pin core through the at least one hollow volume into a fourth aperture in the second side wall. The method may also include aligning an alignment feature of each of the pin cores with an alignment feature of each of the respective apertures. The method may also include securing each of the pin cores into the respective aperture by using adhesive. The method may also include securing each of the pin cores into the respective aperture by packing sand adjacent a distal end of each of the pin cores.
A more complete understanding of aspects described herein and the advantages thereof may be acquired by referring to the following description in consideration of the accompanying drawings, in which like reference numbers indicate like features, and wherein:
In the following description of the various embodiments, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration various embodiments in which aspects described herein may be practiced. It is to be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the described aspects and embodiments. Aspects described herein are capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. Rather, the phrases and terms used herein are to be given their broadest interpretation and meaning. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. The use of the terms “mounted,” “connected,” “coupled,” “positioned,” “engaged” and similar terms, is meant to include both direct and indirect mounting, connecting, coupling, positioning and engaging.
Also, while the terms “top,” “bottom,” “front,” “back,” “side,” “rear,” “upward,” “downward,” and the like may be used in this specification to describe various example features and elements of the disclosure, these terms are used herein as a matter of convenience, e.g., based on the example orientations shown in the figures or the orientation during typical use. Additionally, the term “plurality,” as used herein, indicates any number greater than one, either disjunctively or conjunctively, as necessary, up to an infinite number. Nothing in this specification should be construed as requiring a specific three dimensional orientation of structures in order to fall within the scope of this disclosure. Also, the reader is advised that the attached drawings are not necessarily drawn to scale.
The bolster opening 110 may be defined by a pair of side frame columns 120, a compression member 125, and a spring seat 127. The bolster opening 110 may be sized to receive an outboard end section 205 of a bolster 200 (
A pair of wear plates 135 and a pair of wedges (not shown) may be positioned between shoe pockets 210 of the outboard end sections 205 of the bolster 200 and the side frame columns 120. The side frame columns 120 may include one or more fastening holes 133 configured to receive fasteners to attach the the wear plates 135 to the side frame columns 120 A single exemplary wear plate 135 is illustrated in
Returning to
The mold may be formed by providing patterns (not shown) that define features of the drag side 102 and cope side 103, respectively, of the first side frame 100A and the second side frame 100B. The patterns may additionally define one or more gates 415A and 415B for distribution of molten material within the mold 400. The one or more gates 415A/415B may be positioned in a center region of the mold 400 in between the first side frame 100A and the second side frame 100B to provide for an even distribution of the molten material throughout the mold 400 during casting. For example, gates 415A/415B may be positioned in an area of the mold 400 bordering the compressive member 125 of each of the side frames.
Additionally, one or more risers 425 may be inserted into the cope portion 410 of the mold 400. The risers 425 may be insulating hollow cylindrical structures into which molten material fills during casting operations. The risers 425 may be positioned at areas of the mold that correspond to thicker areas of the side frame that cool more slowly than other areas of the side frame. The risers 425 function as reservoirs of molten material that compensate for contraction that occurs in the molten material as the molten material cools, and thus prevent shrinkage, or hot tearing of the cast side frame in the thicker areas that might otherwise occur. In addition, risers which are open to atmosphere on top work with vents to allow air and mold gas to escape during pouring and filling.
Molding material 420 is then packed over and around the pattern and risers 425 until the mold is filled. The molding material 420 may correspond to a chemical or resin binder material such as phenolic urethane, rather than green-sand products utilized in known casting operations. The chemical binder material product enables forming molds with greater precision and finer details. The molding material 420 is then leveled off and cured to harden. The patterns are removed once the molding material 420 cures.
At block 305, one or more core assemblies 430 that define the interior region of the side frames 100A and 100B are formed. The core assemblies 430 may include a center core 500.
Front, bottom, and side views of center core (which may also be referred to as the bolster core or bolster opening core) 500 are depicted, respectively, in
Regardless of the fabrication method used, center core 500 may include a first side wall 520, a second side wall 540, a bottom wall 550 and top wall 555. Each of the first side wall 520, second side wall 540, bottom wall 550, and top wall 555 may have an inner surface 520a, 540a, 550a, and 555a respectively and an outer surface 520b, 540b, 550b, and 555b respectively. The center core 500 may also include a center column 530 having a first surface 530a and a second surface 530b. One or more apertures or hollow center volumes 510 may be created in center core 500. In one embodiment, the center core 500 may include a first hollow center volume 510a located between the first side wall 520 and center column 530, and a second hollow center volume 510b location in between the second side wall 540 and center column 530. The first hollow center volume 510a may be defined by inner surfaces 520a, 555a, 530a, and 550a, and the second hollow center volume may be defined by inner surfaces 530a, 555a, 540a, and 550a. The outer surfaces 520b, 555b, 540b, and 550b may define the bolster opening 110. The outer surfaces 520b and 540b of the first side wall 520 and the second side wall 540 respectively may be configured to form the side frame columns 120 of the side frame 100.
In alternate embodiments, as shown for example in
Each of the first side wall 520 and the second side wall 540 may include one or more apertures or pin core holes 560. The pin core holes 560 may extend through side walls 520 and 540. The pin core holes 560 may traverse the entirety of side walls 520 and 540 and may form openings on both inner (520a, 540a) and outer (520b, 540b) surfaces of the side walls 520, 540. Each of the one or more pin core holes 560 may be configured to receive or engage a pin core 600 through the inner surface 520a, 540a of the side walls 520 and 540.
Referring now to the pin core 600 in more detail, front, bottom, and side views of a pin core 600 are depicted, respectively, in
Once the pin core 600 is inserted into the center core, the center core engagement portion 606 is configured to be located substantially adjacent the center core 500. The center core engagement portion 606 may be substantially cylindrical or in other embodiments may be tapered forming a frustoconical shape. Additionally, the center core engagement portion 606 may include one or more alignment features 601. The alignment features 601 may reduce incorrect insertion of the pin core 600 into the center core 500. As shown in
The fastening hole portion 608 extends from the center core engagement portion 606. The fastening hole portion is configured to form the fastening hole 133 in the side frame column 120 of the finished side frame 100. The fastening hole portion 608 may be substantially cylindrically shaped and may have a diameter of about 0.081 inches or greater than 0.75 inches.
The adjacent core engagement portion 610 extends from fastening hold portion 608. The adjacent core engagement portion 610 may be substantially cylindrical or as shown in
Referring now primarily to
In other alternate embodiments, on the inner face of the first side wall 520 and second side wall 540, the pin core holes 560 may include indexed pin core slots. The indexed pin core slots may be configured to rotatably receive the one or more pin cores 600 during the installation of the pin cores. Through the rotational insertion, the one or more pin cores 600 may become rigidly fastened into the pin core holes 560. In such instances, adhesive and sand packing may further be used, but are not necessary.
As shown primarily in
The pin cores 600 may have different shapes and/or sizes. For example, as shown in
Returning back to
Once the center core 500 is placed in the mold, the pin cores 500 may then be inserted into the pin core holes 560 through the hollow volumes 510. In some embodiments, the pin cores 600 may be adhered to the center core 500 with an adhesive. The utilization of adhesive may prevent the one or more pin cores 600 from displacing, rotating, or otherwise being expelled from the pin core holes 560 during the pouring of the molten material into the mold 500. In some embodiments, after the pin cores 500 are installed in the pin core holes, sand may be packed over the pin core holes 560 to prevent the expulsion of the pin cores from the pin core holes 560 during the pouring of molten material into mold 500.
Once the cores are in place, the second portion or cope portion 410 may be placed over the drag portion 405 and secured to the drag portion 405 via clamps, straps, adhesive, or weights, and the like. In this regard, locating features may be formed in the drag portion 405 and the cope portion 410 to ensure precise alignment of the respective portions. Molten material, such as molten steel, may then be poured into the mold 400 via gates 415A and 415B at step 315. The molten material then flows through the mold 400 in the space between the mold 400 and the core assemblies 430. At block 320, the mold 400 is removed from the side frames 100A and 100B and the side frames are finished.
Advantageously, the one or more hollow center volumes 510, may provide advantages. For example, the hollow center volumes 510 may serve to reduce the overall weight of center core 500. In some embodiments the overall weight of the center core 500 may be reduced by about 25% to about 40%, or by at least 25%, or by at least 33% compared to known center cores. In some embodiments, the center core 500 may weigh about 150 lbs., or less than about 175 lbs. Additionally, in some embodiments, the pin core holes 560 may be utilized as attachment interfaces for machinery or users to grip the center core 500 while inserting the center core 500 into the mold 400. Further, in some embodiments, the one or more hollow center volumes 510 may allow for increased collapsibility of center core 500 as compared to conventional center cores. The increased collapsibility may provide for ease of removal of center core 500 after the fabrication of side frame 100 is completed. Additionally, the increased collapsibility of the core may reduce casting defects and improve the dimensional consistency of the finished side frame. As is well known, as the side frame casting cools it shrinks. The increased collapsibility may reduce the strain in the corners of the upper bolster opening and lower bolster opening. Additionally, the increased collapsibility may reduce the likelihood of hot tears which may increase the consistency of the side frame. Further, having a more consistent collapse in the bolster area, allows for more precise dimensional control and parallelism of the columns.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
