Railcar couplers are used to connect railcars together. Typical couplers used throughout North America are the Type-EF and Type-F couplers, also referred to as SBE60, SBE69, and or E69 couplers, respectively. These couplers are normally produced through a sand casting process, which offers a low-cost, high-production method for forming complex shapes.
In sand casting, a mold is created using a sand and binder mixture (i.e., molding sand). The binder allows the sand to retain a shape. The most common sand/binder mixture used for casting couplers is green sand, which consists of silica sand, organic binders and water. Green sand is used primarily due to its lower cost.
The mold typically comprises a cope portion (i.e., top half) and a drag portion (i.e., bottom half), which are separated along a straight or offset parting line. To form the cope and drag portions, patterns that define cope and drag portions, respectively, of the coupler and a gating system are placed into separate flasks. Molding sand is then packed around the patterns, to define mold cavities for the coupler and gating system. Draft angles of 3 degrees or more are machined into the pattern to ensure the pattern releases from the mold.
In some instances, two or more couplers may be cast simultaneously by forming the mold around two or more patterns that define multiple couplers in a single flask. For example, two patterns may be arranged side-by-side within the flask. A common gating system may be formed along the longitudinal axis of each pattern and may be configured to feed molten metal to both the head and shank regions of the mold (i.e., those areas of the mold that will correspond to the head and shank sections.)
The patterns are then removed from the mold, and cores for defining various internal cavities of the coupler are placed into the mold. The mold is then closed and filled with hot liquid metal, which is poured into the mold via a down sprue.
After the metal has been poured into the mold, the casting cools and contracts as it approaches a solid state. Risers, which are reservoirs of molten material, are placed at those areas of the casting that exhibit the highest contraction. The risers feed those areas as the casting cools to help minimize the formation of voids, which would otherwise occur. The risers are formed in the cope portion of the mold and typically define openings, which may allows gasses to escape during pouring and cooling.
After solidification, the metal (i.e., raw casting) is removed by breaking away or burning off the rigging. The casting is then finished and cleaned via grinders, blasting, welding, heat treatment, or machining.
The casting techniques described above have several disadvantages. First, the binders used in the in the molding sand can have a significant effect on the final product, as they control the dimensional stability, surface finish, solidification, and casting detail achievable in each specific process. In particular, couplers cast in green sand have a relatively poor dimensional stability and surface finish. These couplers may also exhibit a higher rate of defects due to solidification issues.
As noted above, two or more couplers are sometimes formed in a single flask. However, the size of the flask has to be relatively large because of the way in which the gating system is arranged with respect to the coupler cavities. Other problems with these casting operations will become apparent upon reading the description below.
An object of the invention is to provide a casting mold with the rigging and/or gating system for casting a railcar coupler. The railcar coupler includes a shank portion and a head portion. The casting mold includes cope and drag portions that define an external shape of the coupler. The casting mold assembly also includes one or more cores that define an interior of the shank portion and a separate head core with an exterior that defines at least an interior of the head portion including the lock chamber, guard arm side portion, and knuckle side portions of the head. The head core comprises at least one portion that defines a front face gating system that includes a channel that runs in a generally vertical direction through a center of the portion and at least one in-gate configured to direct molten material to top and bottom regions of the head to define the lock chamber, guard arm side portion, and knuckle side of the head.
Another object of the invention is to provide the casting mold with the rigging for casting a railcar coupler that includes a shank portion and a head portion. The casting mold includes cope and drag portions that define an external shape for each of at least two couplers. The couplers are nested together and oriented in opposite directions to one another along respective longitudinal axes. A down sprue is centered between the first and second couplers and is configured to direct molten material to a gating system positioned between the at least two couples.
Another object of the invention is to provide a casting method for casting a railcar coupler. The coupler includes a shank portion and a head portion. The casting method includes providing cope and drag portions of the mold that define an external shape of the coupler, providing one or more cores that define at least an interior of the shank portion, and providing a separate head core with an exterior that defines an interior of the head portion including the lock chamber, guard arm side portion, and knuckle side portions of the head. The head core comprises at least one portion that defines a front face gating system that includes a channel that runs in a generally vertical direction through a center of the at least one portion and at least one in-gate configured to direct molten material to top and bottom regions of the head to define the lock chamber, guard arm side portion, and knuckle side of the head.
Another object of the invention is to provide a casting method for casting a railcar coupler. The coupler includes a shank portion and a head portion. The casting method includes providing cope and drag portions of the mold that define an external shape for each of at least two couplers. The couplers are nested together and oriented in opposite directions to one another along respective longitudinal axes. Also provided is a down sprue that is centered between the first and second couplers configured to direct molten material to a gating system positioned between the at least two couplers.
Other features and advantages will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional features and advantages included within this description be within the scope of the claims, and be protected by the following claims.
The accompanying drawings are included to provide a further understanding of the claims, are incorporated in, and constitute a part of this specification. The detailed description and illustrated embodiments described serve to explain the principles defined by the claims.
a illustrates a side view of fin in-gates of the gating system;
b illustrates a section of the drag mold that forms that the fin in-gates;
The embodiments below generally describe a rigging system for manufacturing railcar couplers. The rigging may be arranged within an outer mold that includes a cope portion and a drag portion. The cope and drag portions may be formed from a relatively low-cost molding material, such as no-bake or air-set sand, which may have a grain fineness number (GFN) in the range of 44-55 GFN. The molding material may be new sand or reclaimed sand. That is, sand that has been previously used to make castings. The reclaimed sand may be obtained by subjecting used molds to various shaking, thermal, and/or crushing operations that break down the sand into finer and finer constituent sizes until a desired grain size is obtained. Screening operations facilitate separation of the sand by size. Finally, the sand is subjected to high temperatures to burn off any residual coating or other impurities, such as the binder material. The reclaimed sand is then mixed with new binder at a ratio of about 99:1 and placed into a mold and allowed to set. Once set, the new mold is ready to receive a molten material.
In some implementations, two or more grades of molding material may be used to form the outer mold. For example, an outer layer of the mold (i.e., that defines the exterior of the outer mold may be formed from less-refined sand and/or relatively small blocks broken from used molds. The less-refined material may not be subjected to the various separation operations described above. For example, thermal operations may not be carried out to save time. Moreover, a lesser amount of binder material may be utilized to bind the less-refined material. For example, the ratio of sand to binder may be greater than 99:1.
An inner layer of the mold may be formed from the more-refined sand reclaimed via the separation processes described above. Utilizing the different grades of reclaimed material reduces overall manufacturing costs associated with the outer mold as less refined sand is required. The more-refined sand may be reserved for just those portions of the mold that require improved surface finish and/or greater dimensional accuracy, such as the internal cavities, gating system, and the like.
The disclosed rigging system includes a one-piece head core 225 that defines the interior of the head of a coupler along with a front face gating system that is configured to feed molten material throughout the head. While a one-piece head core is shown, it is understood that the head core could comprise more than one portion.
The rigging system also facilitates the casting of two couplers via a common gating system positioned in-between the couplers. In particular, two rigging system embodiments are disclosed. The first embodiment is configured to cast Type E couplers. The second embodiment is configured to cast longer Type EF couplers. For example, the first embodiment may be used for casting SBE60EE and SBE67DE couplers. The second embodiment may be used for casting E69CE, EF601AE, EF528CE, SBE69CE, and EF5110E. It is understood, however, that these casting embodiments may be adapted to cast a greater number of couplers simultaneously and/or different types of couplers.
Referring to the figures, the rigging 200 includes a head core 225 and a butt-end core 230. The head core 225 is configured to define interior features of the coupler 100. The butt-end core 230 is configured to define the exterior features of the back end of the shank 110. The head core 225 may be formed from one unitary body of material or may be formed from smaller core sections that combine to form the head core 225. Other cores for defining other interior features may be provided. Further details of the head core 225 and butt-end core 230 are described in U.S. application Ser. No. 13/337,558, which is incorporated by reference in its entirety.
The rigging 200 also includes a front face riser 235, a knock-off top riser 205, a tail riser 210, a down sprue 215, and a gating system 240. The outer mold defines the exterior features of the coupler 100 along with various portions of the rigging 200 including the gating system 240, knock-off top riser 205, and tail riser 210, front face riser 235, and down sprue 215.
The tail riser 210 has a height of about 10.9 in and a top diameter of about 5 in that tapers to a smaller diameter towards the coupler 100. The tail riser 210 is positioned over the tail end of the shank 110 of the coupler 100, and is configured to feed molten material to the solid tail end of the shank 110 while the casting cools.
The fin in-gates 405 may be entirely formed in the drag portion of the outer mold. Referring to
In some implementations, the fin cores 505 are formed by an opening 515 defined between a fin core 505 and an in-gate channel 510 of the drag portion. The fin cores 505 are configured to be inserted into in-gate channels 510 of the drag portion. Each fin core 505 and in-gate channel 510 combination defines an opening 515 that matches the cross-sectional width and height of a fin in-gate 405.
Referring to
Referring to
Referring to
In operation, molten material is poured into the down sprue 215. The molten material then flows through the runners 410, through the fin in-gates 405 and then fills the cavities between the cores and the outer mold to define the couplers 100. As the cavity fills, the risers 220 begin to fill. The relative angles formed between the runners 410, fin in-gates 405, and shank 110, along with the dimensions of the fin in-gates 405, control the rate and location at which molten material flows in the respective cavities that define the first and second couplers 100, illustrated in
The molten material continues to fill the various components that define the head 105. For example, the molten material fills the knock-off top riser 205 and then the front face riser 235. As the casting solidifies, the molten material in the front face riser 235 flows through the front face gating system 705 and through the upper and lower in-gates 720 and 725 to fill the cavities that define the interior of the head 105.
As the molten material cools and begins to contract, molten material in the risers 210 and 205 and the front face riser 235 continue to flow into the cavities to thereby prevent voids from forming in the casting.
After the material hardens, the gating system 240, front face gating system 705, risers 210 and 205, and front face riser 235 may be removed from the cast coupler 100. The relatively small cross-section of the fin in-gates 405 facilitates easy separation of the fin in-gates 405 and, therefore, the gating system 240, from the cast coupler 100. For example, a relatively low amount of torque may be applied to the gating system 240 relative to the coupler 100 to simply crack the gating system 240 off of the coupler 100. The knock-off top riser 205 and the front face gating system 705 may be removed via impact or the like. The remaining portions of the casting (i.e., the gating system, risers, down sprue, etc.) may be melted down and used in subsequent casting operations.
As described above, the casting system advantageously allows for the casting of two couplers 100 in a single casting operation. Due to relative positioning of the couplers 100 and the gating systems 240 and 705, the size of the outer mold can be kept to a minimum. For example, the surface area of the cope of the outer mold may be about 13 ft2 as illustrated by reference B in
Referring to the figures, the rigging 1200 includes a head core 1225 and a butt-end core 1230. The head core 1225 is configured to define interior and exterior features of the coupler 1100. The butt-end core 1230 defines the exterior features of the back end of the shank 1110. Other cores for defining other interior features may be provided. Further details of the head core 1225 and butt-end core 1230 are described in U.S. application Ser. No. 13/337,558, which is incorporated by reference in its entirety.
The rigging 1200 also includes a front face riser 1235, a knock-off top riser 1205, a tail riser 1210, a down sprue 1215, and a center gating system 1240. The outer mold defines the exterior features of the coupler 1100 along with various portions of the rigging 1200, including the center gating system 1240, knock-off top riser 1205, tail riser 1210, front face riser 1235, and a down sprue 1215.
The head 1105 may be cast in a similar manner as described above. For example, a head core 1225 may define interior features of the head 1105 and may include a cavity and in-gates configured to feed molten material through the head 1105. A knock-off top riser 1205 and front face riser 1235 feed molten material to the head 1105 as the casting cools.
The center gating system 1240 includes a down sprue 1215, a pair of runners 1245, a pair of risers 1220, and a pair of in-gates 1250. The dimensions of the down sprue 1215 may be about the same as the down sprue 215 illustrated in
The runners 1245 couple the down sprue 1215 to the risers 1220 and run in a direction that is generally parallel to a longitudinal axis of the shank 1110. In a first runner section 1410 that connects to the down sprue, the diameter D1 of each runner 1245 is about 2.0 in. In a second runner section 1405 that connects to a riser, the diameter D2 of each runner 1245 is about 3.1 in. Referring to
The in-gates 1250 are coupled to first and second sections of the shank 1110 to facilitate more even distribution of molten material to the shank 1110 of the coupler 1100. A first in-gate is positioned between the midpoint of the shank 1110 and the head 1105. A second in-gate is positioned between the midpoint of the shank 1110 and the opposite end of the coupler 1100. This double feed to the shank 1110 facilitates even filling and cool down of the shank 1110 of the coupler 1100. The in-gates 1250 shown in the figures enter the shank 1110 from a side of the shank 1110. However, in alternative embodiments, the in-gates 1250 may be configured to enter the shank 1110 from a bottom side of the shank 1110 to bottom-feed the coupler. The principles and advantages of bottom feeding are described in U.S. application Ser. No. 13/194,704, which is hereby incorporated by reference.
The tail riser 1210 is positioned at the end of the shank 1110, opposite the head 1105, and offset to the side of the shank 1110 so that it feeds the end of the shank though a channel 1305. The longitudinal axis of the channel 1310 forms an angle E of less than 90° with the longitudinal axis of the shank 1110, as illustrated in
The in-gates 1250 are formed in both the drag portion and cope portion of the outer mold to promote bottom feeding of the metal into the shank 1110. The angle, B, formed between the longitudinal axis of a given in-gate 1250 and the longitudinal axis of a given runner 1245 may be about 90 degrees. Referring to
In operation, molten material is poured into the down sprue 1215. The molten material then flows through the runners 1245 and into the risers 1220. The molten material then flows through the in-gates 1250 and then into the cavities between the cores and the outer mold to define the couplers 1100. The molten material continues to flow into the head 1105 through the front face gating system 705. As the cavities in the mold fill, molten material starts to fill the risers 1220 in the center gating system 1240, front face riser 1235, knock-off top riser 1205, tail riser 1210, and finally through the front face gating system 705, as described above. The head pressure at the opening in the top of the down sprue 1215 forces substantially the entire space within the risers 1220 to fill with molten material.
The small diameter of the first runner section 1410 tends to control the rate at which molten material flows into the second runner section 1405, which is larger, and then into the respective cavities that define the first and second couplers 1100, illustrated in
As shown above, the casting system advantageously allows for the casting of two couplers 1100 in a single casting operation. Due to the relative positioning of the couplers 1100, the center gating system 1240, and the availability of the front face gating system 705, the size of the outer mold can be kept to a minimum. For example, the surface area of the top surface of the cope may be about 23 ft2, as illustrated by reference D in
The gating system is formed in both the cope and drag portions of the outer mold and is configured to direct molten material into two cavities that define the exterior of the couplers. The gating system includes a down sprue, a pair of runners, and fin in-gates or in-gates. The gating system is configured so that molten material poured via the down sprue travels through the runners, then the fin in-gates or in-gates, and finally into the cavities that define couplers.
In a first embodiment, fin in-gates 405 are utilized and may be entirely patterned in the drag portion of the outer mold. The fin in-gates are arranged so that an angle formed between the longitudinal axis of a given fin in-gate and the longitudinal axis of a runner may be about 60 degrees. Likewise, the angle formed between the longitudinal axis of a given fin in-gate and the longitudinal axis of the shank of the coupler may be about 60 degrees.
In a second embodiment, in-gates 1250 are utilized and may be entirely formed in one or the other portion of the outer mold. The angle formed between the longitudinal axis of a given fin in-gate 1250 and the longitudinal axis of a given runner may be about 90 degrees.
At block 1705, the head core, butt-end core, and other cores (e.g., fin cores etc.) may be inserted into the outer mold. The head core is configured to define the interior surface of the head of the coupler and also defines a cavity in an interior region of the head core configured to serve as a front face gating system for feeding molten material throughout the head. The front face gating system may include an upper in-gate and a lower in-gate configured to feed molten material into upper and lower portions, respectively, of the head of the coupler. The head core may include an opening positioned below a riser formed in the cope portion.
At block 1707 the mold is closed. At block 1710, molten material is poured into the down sprue of the outer mold. The molten material flows through the gating system and into the cavities formed between the outer mold and the cores, as well as the risers. Molten material also flows through the front face gating system to define the interior features of the head of the coupler.
At block 1715, the hardened casting is removed from the mold. For example, the mold may be broken apart to expose the casting. The spent mold may be broken down and reused to form subsequent molds.
At block 1720, the couplers are separated from the gating and risers. For example, the gating systems in the head and along the shank may be hammered to break the connection formed between the respective systems and the coupler.
At block 1725, the couplers are finished. For example, the sides of the coupler shanks to which the fin in-gates are connected may be ground to a relatively smooth finish. The inner surface of the head may be finished to remove residual material from the in-gates of the front face gating system. Residual material from the knock-off top riser may be ground as well. The remainder of the coupler may then be sand blasted to a smooth surface finish. Other finishing operations, such as weld repair, heat-treating, gauging, etc. may also be performed. The coupler may be ready for operational use after the finishing operations.
As described, the embodiments facilitate forming the couplers in a minimum of space and a minimum of finishing. While various embodiments of the embodiments have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the claims. The various dimensions described above are merely exemplary and may be changed as necessary to facilitate casting different components. Accordingly, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the claims. Therefore, the embodiments described are only provided to aid in understanding the claims and do not limit the scope of the claims.