CZ2012966A3 - Process for producing railway car swing beam - Google Patents

Abstract

A method of manufacturing a railcar cradle that includes a pair of friction shoe recesses arranged at respective ends to allow insertion of the cradle into the cradle mounting hole provided in the respective side frames includes providing a bogie cradle model for forming the bottom and top of the casting mold and providing one or more cores that define an inner region of the cast bogie cradle, wherein the bogie cradle model and one or more cores are arranged in a first embodiment variant such that the margin of tolerance of the recess angle for the friction shoe is in the range of about + -. And in a second embodiment variant, the width variation between the individual recesses forming the pair of recesses for the friction shoes is in the range. + -. 0.063 inches, which is 1.600 mm. A third embodiment of the method of manufacturing a railcar cradle includes providing a bogie cradle model to form a bottom and top of the casting mold and providing one or more cores that define an inner area of a cast bogie cradle, at least some of the cores defining one or more stamps to accommodate one or the plurality of cores inside the bottom of the casting mold and wherein the distance between the outer surface of the one or more marks and the bottom surface of the casting mold, which is closest to the outer surface of the one or more marks, is less than 0.030 inches, or equal to or equal to 0.762 mm.

Description

Railway cars generally consist of a railway car body which rests on a pair of bogie assemblies. The chassis assemblies include a pair of side frames and wheelsets interconnected via a cradle and suspension system. The car body is mounted on the center mandrel of the cradle, which acts as the center of rotation of the chassis system. Springs and friction wedge dampers respond to the movements of the car body, by means of which the cradle and side frames are connected. The side frames include axle bearing housings, each of which defines the extent to which the wheel assembly of the respective wheelset is mounted by means of a roller bearing extension.

Chassis side frames and cradles can be manufactured using a variety of die casting processes. The most common process used in the manufacture of these components is sand casting. Sand casting technology is an inexpensive, highly productive way of producing castings with complex hollow shapes, including the side frames and cradles of railway car chassis. In a typical sand casting process, a mold is formed by compacting sand around a model, which generally includes an inlet system, then the model is removed from the mold, the cores are placed in the mold and the mold is closed, then the mold is filled with hot liquid metal through the inlet system. , φ the metal is allowed to cool in the mold, then the φ solidified metal, referred to as the raw casting, is removed by breaking the mold and finally the casting is subjected to finishing and cleaning, which may include the use of grinders, cutting torches, heat treatment equipment and machine tools. In carrying out the sand casting process, the required mold is formed using sand as the base material, which is mixed with the binder needed to maintain the shape. The mold is composed of two halves, which are the top of the mold (upper part) and the bottom of the mold (lower part) and which are separated from each other by a dividing plane. The sand is compacted around the model and retains the obtained shape even after pulling the model out of the mold. Bevels are created on the model, the angles of which are at least 3 degrees and which ensure the release of the model surfaces from the mold walls during the drawing of the model. Some sand casting technologies use a molding frame to support the sand during the molding process as well as during the casting process. After inserting the cores into the mold, it is closed by placing the top of the mold on the bottom of the mold.

In the casting of a complex or hollow part, cores are used to define the hollow inner parts.

spaces or complex cross-sections that cannot be created in any other way, ie using a model. These cores are usually formed by forming sand and binders in a core, the shape of which corresponds to the shape of the element formed by the core. The compaction of the molding mixture in these feeders is carried out either manually or mechanically, using a blower. After removal from the core, the cores are inserted into the mold. The cores are positioned in the mold by means of marks which, when the cores are inserted, ensure that they are guided and subsequently prevented from moving during the casting of the metal. In addition, supports can be used to support or restrict the movement of the cores and dissolve into the parent metal during solidification.

The mold generally includes an inlet system that forms a path for feeding molten metal and regulates the flow of this metal into the mold cavity. This inlet system consists of an inlet channel, which regulates the flow rate of the metal, and of points for connecting the pouring channels. The casting channels serve to guide the metal into the inlet notches leading to the mold cavity. The inlet notches regulate the amount of metal fed into the mold cavity and prevent swirling of the liquid metal.

The casting of the metal into the mold is followed by a cooling phase of the casting, which gradually shrinks during solidification. During the shrinkage of the metal, additional liquid metal must continue to be fed to the areas where this shrinkage occurs, as otherwise there would be shrinkage in the finished part. In areas with a high degree of shrinkage, risers are placed in the mold, which serve as auxiliary containers for the material to be filled during casting. These risers are the last areas to solidify, allowing their contents to remain in a liquid state for longer than the cast part located in the main cavity of the mold. During the cooling of the contents of the main cavity of the mold, these risers then supply the areas in which shrinkage takes place and thus ensure the production of a complete finished casting. The risers, which are open at the top of the top of the mold, can also act as vent vents to allow gases to escape during casting and cooling.

Different casting processes use different binders that allow the sand to retain the shape specified by the model. These binders have a great influence on the final product, as they determine the dimensional stability and surface properties of the casting as well as the possibility of casting details in each specific process. The most typical methods of sand casting include the use of raw sand consisting of silica sand, organic binders and water, and materials based on chemical or resin binders consisting of silica sand and fast-setting chemical binder adhesives, such as phenolic urethane. Chassis side frames and cradles are traditionally manufactured using a raw mold casting process, i.e., raw sand molds, due to lower molding costs. Although this method of manufacturing these components has been considered efficient for many years, it has several disadvantages.

There are several problems with side frames and bogie cradles manufactured using the above-mentioned green casting process. First of all, relatively large bevel angles are needed on the models, which means that bevels with the appropriate size of angles must also have castings produced in this way. In areas where straight cross-sections are required, for example in the area of the axle bearing housings at the side frames and in the area of the friction shoe recesses at the chassis cradle, cores must be used to form these shaped elements. These cores tend to move and lift during casting due to buoyancy. These movements can result in unstable dimensions of the final products, prolongation of the surface treatment time or even scrapping of the part, if the range of dimensional tolerances is not observed. Other problems associated with these casting procedures will become apparent upon reading the description below.

SUMMARY OF THE INVENTION

The object of the invention is to provide a method of manufacturing a mold for casting a side frame of a railway car bogie. The side frame includes front and rear axles defined by an axle bearing housing for mounting the wheel assembly of the respective wheelset. The method includes forming the bottom and top of a mold from a foundry molding material, which mold parts define an outer surface of the bottom and bottom, respectively. the upper part of the side frame. The mold includes a section for casting the area of the axle bearing housing on the side frame, including the ceiling of the axle bearing housing, the contact surfaces, the outer vertical portion of the axle and the inner vertical portion of the axle. The bottom and top of the mold are then cured.

Another object of the invention is to provide a method of manufacturing cores used in connection with a mold for casting a railway car bogie side frame, the side frame comprising front and rear axles defined by an axle bearing housing for mounting a wheel set of a respective wheelset. extends from the respective end of the side frame to the opening of the side frame for accommodating the bogie cradle. The method includes forming separate lower and upper core portions for at least one axle bearing housing. The lower and upper parts of the axle box core define the inner region of the at least one axle box on the side frame. The method further includes joining the lower and upper portions of the axle box core to form an axle box core assembly for insertion into a mold.

Another of a number of objects of the invention is to provide a method of manufacturing a side frame of a railway car bogie, said side frame comprising front and rear axles defined by an axle bearing housing for mounting a wheel assembly of a respective wheelset. The method involves the preparation of a mold which, with its bottom resp. the top defines the outer surface of the at least one axle bearing housing. The molten steel is then poured into a mold and allowed to solidify. The cast side frame, which consists of the final part, the risers and the inlet system, is then removed from the mold. Subsequently, the excess material is abraded from the side frame casting to form a finished side frame. The amount of excess material to be removed from the casting, consisting of burrs at the core points, bulges at the parting plane, risers, inlet system and vents, is less than 10% of the gross weight of the steel that was originally cast in the mold side frame.

Another of the many objects of the invention is to provide a side frame of a railway car chassis which comprises on the one hand a pair of frame webs defining a cradle mounting opening and on the other hand a pair of axle bearing housings which extend in the direction away from the respective side frame webs. Each axle bearing housing defines an area that is arranged to allow the wheel assembly of the respective wheelset to be attached. The side frame further comprises a first rib which is located on the inside of each of the frame webs, i.e. on the side which is opposite to the side of the frame web facing the cradle. An opening is created in each of the webs of the side frame. This opening extends from the side of the respective frame web facing the cradle to the inside of the same frame web. The hole passes through the first rib and its size is selected to allow the insertion of bolts for attaching the wear plate to the side of the frame web facing the cradle.

Another of a number of objects of the invention is to provide a method of manufacturing a railway car bogie cradle. The method includes preparing the bottom and top of the mold. A parting plane is formed in the section of the main mold body which separates the lower half from the upper mold half and which is substantially centered between the two mold halves, these mold halves defining the openings for accommodating the brake device in the sides of the cradle. The method further includes inserting one or more cores into a mold and casting the cradle.

Another of a number of objects of the invention is to provide a core assembly for use in the manufacture of a railway car bogie cradle. The core assembly includes a core for the main body that defines substantially the entire inner region of the cradle that extends from the center of the cradle toward inwardly directed wedge protrusions located at the outer end sections of the cradle and that partially defines an inner end portion of the cradle that extends from the inward. facing wedge lugs towards the outer ends of the cradle. The set of cores also includes end cores

-5-cores that define an inner region of the end section of the cradle end section that is not defined by the core for the main body.

Another of a number of objects of the invention is to provide a method of manufacturing a mold for casting a cradle of a railway car bogie. The method includes forming the bottom and top of a mold from a foundry molding material, which mold parts define the bottom and bottom, respectively. the upper part of the cradle surface. The parting plane which separates the bottom of the mold from the top of the mold is substantially centered between these mold halves, which define the openings for accommodating the brake device in the sides of the cradle. The method also includes curing the bottom and top of the mold.

Another of a number of objects of the invention is to provide a core assembly for use in the manufacture of a railway car bogie cradle. The core assembly includes a core for the main body that defines substantially the entire inner region of the cradle that extends from the center of the cradle toward inwardly directed wedge protrusions located at the outer end sections of the cradle and that partially defines an inner end portion of the cradle that extends from the inward. facing wedge protrusions towards the respective ends of the cradle. The core assembly also includes end cores that define an inner region of the end portion of the end portion of the cradle that is not defined by the core for the main body.

Another of a number of objects of the invention is to provide a method of manufacturing a mold for casting a cradle of a railway car bogie. The method includes forming the bottom and top of a mold from a foundry molding material, which mold parts define the bottom and bottom, respectively. the upper part of the cradle surface. The parting plane which separates the bottom of the mold from the top of the mold is substantially centered between these mold halves, which define the openings for accommodating the brake device in the sides of the cradle. The method further includes curing the bottom and top of the mold.

Another of a number of objects of the invention is to provide a method of manufacturing a railway car bogie cradle. The method involves preparing a mold that includes a bottom and a top of the mold. The parting plane which separates the bottom of the mold from the top of the mold is substantially centered between these mold halves, which define the openings for accommodating the brake device in the sides of the cradle. The method further includes casting the molten steel into a mold and allowing the casting to subsequently solidify. The cradle casting, which is then removed from the mold, consists of a cradle body having a final shape, risers and an inlet system. Subsequently, the excess material is removed from the cradle casting by grinding, thus creating a finished chassis cradle. The amount of excess material to be removed from the casting, which is formed by lumps at the cores, risers and inlet system, is less than 15% of the gross weight of the steel that was originally cast in the mold to produce the bogie cradle.

.! ··;

Another of a number of objects of the invention is to provide a method of manufacturing a railway car bogie cradle, which method comprises preparing the bottom and top of a mold. A dividing plane is formed in the section of the main mold body which separates the lower half from the upper half of the mold and which is substantially centered between the two mold halves, these mold halves defining openings for accommodating the brake device in the sides of the cradle. Next, one or more cores are inserted into the mold, and then molten metal is poured into the mold, thereby casting the bogie cradle. Another of a number of objects of the invention is to provide a method of manufacturing a side frame of a railway vehicle bogie, said side frame defining an opening through which the bogie cradle is located. The opening is defined by a pair of facing webs, a spring carrier and a pressure transfer member. The side frame model for forming the bottom and top of the casting mold is prepared together with one or more cores that define the inner area of the side frame casting. The side frame model and the one or more cores are arranged to define a spacing of the facing webs with a tolerance of about ± 0.038 inches.

Another of a number of objects of the invention is to provide a method of manufacturing a side frame of a railway vehicle chassis, the method comprising preparing a side frame model for forming the bottom and top of a mold and preparing one or more cores defining an inner area of the side frame casting. one of these cores is defined by one or more marks for determining the position of the respective cores inside the bottom of the mold. The distance between the outer surface of the one or more stamps and the bottom surface of the mold which is closest to the outer surface of the respective stamps is less than or equal to about 0.030 inches.

Another of the many objects of the invention is to provide a method of manufacturing a railway car bogie cradle, which comprises a pair of friction shoe recesses arranged at respective ends so as to allow insertion of the cradle into cradle mounting holes which are formed in the respective side frame. The method includes preparing a cradle model to form the bottom and top of the mold and preparing one or more cores that define the inner region of the cradle casting. The cradle model and one or more cores are arranged to define recess angles for the feet with a tolerance of about ± 0.5 °.

Another of the many objects of the invention is to provide a method of manufacturing a railcar bogie cradle, which comprises a pair of foot recesses at respective ends and which is arranged to be inserted into cradle mounting holes which are formed in respective side frames. . The method includes preparing a cradle model to form the bottom and top of the mold and preparing one or more cores that define the inner region of the cradle casting. The cradle model and one or more cores are arranged to define a width between the recesses forming a pair of recesses for the feet with a tolerance of about ± 0.063 inches.

Another of a number of objects of the invention is to provide a method of manufacturing a railway car bogie cradle. The method includes preparing a cradle model to form the bottom and top of the mold and preparing one or more cores that define the inner region of the cradle casting. For at least some of these cores, one or more marks are defined to determine the position of the respective cores inside the bottom of the mold. The distance between the outer surface of the one or more stamps and the bottom surface of the mold which is closest to the outer surface of the respective stamps is less than or equal to about 0.030 inches.

Another of the many objects of the invention is to provide a mold for casting a side frame of a railway car bogie. The side frame includes front and rear axles defined by an axle bearing housing for mounting the wheel assembly of the respective wheelset, the mold comprising a bottom and a top of the mold which are formed by a foundry molding material and define an outer surface of the bottom and bottom, respectively. the upper part of the side frame. The mold further comprises a section for casting at least one surface defined by the axle bearing housing on the side frame.

Another of a number of objects of the invention is to provide a cradle for a railway car chassis which is formed by casting into a mold. The chassis cradle includes a lower part and an upper part. The parting plane which defines the lower part and the upper part of the casting is arranged so that in the area of the main body of the cradle it is substantially centered between the openings for accommodating the brake device in the sides of the cradle.

Another of a number of objects of the invention is to provide a mold for the production of a railway car bogie cradle. The mold includes the bottom of the mold and the top of the mold. The parting plane which separates the bottom of the mold and the top of the mold is arranged so as to be substantially centered between the sections of the mold which define the openings for accommodating the brake device in the sides of the cradle.

Another of a number of objects of the invention is to provide a cradle for a railway car chassis which is formed by casting into a mold. The chassis cradle includes a lower part and an upper part. The parting plane which defines the lower part and the upper part of the casting is arranged so that the outer end sections are essentially defined by the lower part of the casting.

Another of a number of objects of the invention is to provide a mold for the production of a railway car bogie cradle. The mold includes the bottom of the mold and the top of the mold. The respective mating surfaces of the bottom of the mold and the top of the mold have a non-planar complementary shape.

Other features and advantages will or will be apparent to those skilled in the art upon review of the following figures and detailed description. In doing so, all such additional features and advantages set forth in this specification are considered to fall within

of the overall scope defined by the following claims and protected by those claims.

DRAWINGS

The purpose of the accompanying drawings, which form a part hereof, in which they are incorporated, is to provide a clearer explanation of the claims. The detailed description of the preferred embodiments of the invention, which refers to the illustrations, serves to clarify the principles defined in the claims.

FIG. 1A and IB show in perspective respectively side view example of a side frame of a railway car chassis.

FIG. 2A and 2B show an example of an inner surface of a side frame web that includes a pair of frame web reinforcements.

FIG. 3 shows an example of the extent defined by the axle bearing housing on the cast side frame.

FIG. 4 shows an example of a sequence of operations included in the side frame manufacturing process.

FIG. 5A shows an example of the bottom and top of a casting mold for making a side frame casting.

FIG. 5B shows examples of risers and inlet system on a side frame casting.

FIG. 6 shows an example of cores that can be used in conjunction with a mold.

FIG. 7 shows an example of a chassis cradle that can be used in combination with the above-mentioned side frame.

FIG. 8 shows the risers and the inlet system on the bogie cradle casting.

FIG. 9A shows an example of a mold for making a bogie cradle casting.

FIG. 9B shows an example of a bogie cradle casting made in the mold of FIG.

9A.

FIG. 9C shows an example of a partial cross-section of a mold for casting a bogie cradle and a core mounted therein.

FIG. 10A shows a cross section of the bogie cradle in the area of the opening for accommodating the brake device.

FIG. 10B is a cross-sectional view of a friction shoe recess formed in a bogie cradle. FIG. 11 shows a core assembly that can be used in conjunction with a mold to make a bogie cradle.

FIG. 1 shows a perspective view of a side frame 100 of a railway car bogie. A railroad car may correspond to a rail freight car, such as is used in the United States to transport loads with a total weight in excess of 220,000 pounds. The side frame 100 includes an opening 110 for receiving a bogie cradle and a pair of axle bearing housings 105. The bogie cradle mounting hole 110 is defined by a pair of side frame webs 120, a pressure transfer member 125, and a spring carrier 127. The size of the bogie cradle mounting hole 110 is determined so that the outer end portion 705 (Fig. 7) of the cradle 700 (Fig. 7) can be accommodated therein. Between the outer end sections 705 of the cradle 700 and the spring carrier 127, a spring group (not shown) is located, which forms a resilient bond between the cradle 700 and the side frame 100.

Between the friction shoe recesses 710 formed in the outer end sections 705 of the cradle 700 and the side frame web 120, a pair of wear plates 135 are located. In Fig. 1a, only a single wear plate 135 is shown in a separate state for illustrative purposes. The wear plates 135 and friction wedges (not shown) act as shock absorbers that prevent permanent transmission of vibration between the side frame 100 and the cradle 700. Each wear plate 135 may be made of metal. The abrasion plates 135 are arranged to be attached to the side of the side frame web 120 that faces the cradle 700 (i.e., to that side of the side frame web 120 that is on the cradle mounting side). The wear plates 135 may be secured by fasteners, such as bolts or bolt and nut assemblies, that allow the wear plates 135 to be removed.

In operation, the movement of the cradle 700 within the cradle mounting hole 110 creates a pressure that acts on the wear plates 135. In known side frames, the webs 120 of these frames tend to elastic deformation as a result of these wedge pressures. As a result, the connecting parts by means of which the wear plates 135 are attached to the webs 120 of the side frame are loosened. In order to overcome these problems, one variant of the embodiment of the side frame 100 according to the invention comprises reinforcements 205 of the frame webs (Fig. 2), which are designed as ribs 205 located on the webs 120 of the side frame.

FIG. 2A and 2B show an example of an inner surface 130 of a side frame web 120 that includes a pair of frame web reinforcements 205. The frame web reinforcements 205 are arranged on the inner surfaces of the side frame webs 120 and extend between the side surfaces of the side frame 100. centered between holes 110 formed in the side frame webs 120 for the connecting members described above. The thickness T, which is indicated by reference numeral 203, of the side frame webs 120 may be about 1.125 in the area of the frame web reinforcements 205, as opposed to 0.625 which is used for known side frame webs that are not frame reinforced. The frame reinforcements 205 increase the rigidity of the side frame webs 120, thereby preventing the side frame webs 120 from deforming under the pressures described above. In addition, the frame reinforcements 205 increase the length over which the fasteners are clamped. In other words, the clamped part of the connecting part is longer than with the known side frames. This allows the fasteners to be prestressed over a longer section during fastening, creating a greater clamping force and extending the fatigue life of the bolted joint.

It is further apparent from the illustration in Fig. 1A that each axle bearing housing 105 defines an area 140 into which the wheel assembly of the respective bogie wheels is mounted. Each axle 140 defined by the axle box includes the axle box stop 116, the outer vertical arm 117 and the inner vertical arm 118 and the inner and outer contact surfaces 115, which together form support brackets in a known manner and which are in direct contact with the respective assembly surfaces. extensions and wheels with which they complement each other. The contact surfaces 115 are crucial for aligning the wheel assemblies within the ranges 140 defined by the axle bearing housings. To allow proper alignment, the mating surfaces 115 are cleaned during the finishing process to remove defects remaining after the casting process.

FIG. 3 shows an example of the elevation 140 defined by the axle bearing housing on the side frame 100 after the side frame has been removed from the mold 500 (FIG. 5A), but before finishing finishes. In this state, the contact surfaces 115 are not planar. Instead, the contact surfaces 115 are chamfered at an angle whose magnitude D, indicated by reference numeral 305, corresponds to the bevel angle of the casting mold for making the side frame 100, as will be described in more detail below. The bevel angle D can be about 1 ° or less, which is less than the bevel angles of known cast side frames, which can be larger than 3 °. In one preferred embodiment of the invention, the bevel angle is about 3/4 °. Other parts of the casting may also have smaller bevel angles. Bevel angle less than 3/4 °,

For example, the ceiling 116 may have an axle bearing housing ceiling 116. Also, the bevel angles of the vertical arms 117 and 118 may be less than 3/4 °. The smaller the bevel angle, the smaller the amount of finishing required to create a planar surface. The contact surfaces 115 of the side frame 100 therefore require a shorter finishing time than the corresponding surfaces of the known cast side frames, because in the area of the axle bearings there are no leaks which otherwise occur at the core locations.

FIG. 4 shows an example of a sequence of operations included in the manufacturing process of the side frame 100 described above. The description of the operations is better understood with reference to FIGS. 5 and 6. In block 400, a mold 500 for manufacturing the side frame 100 is formed. 5A, it will be appreciated that the mold 500 may include a mold bottom 505 and a mold top 510. The bottom 505 of the mold 500 includes a cavity formed to have a shape corresponding to the lower portion 102 of the side frame 100. The top 510 of the mold includes a cavity formed to have a shape corresponding to the upper portion 103 of the side frame 100.

The respective mold halves can be formed using pre-prepared first and second models (not shown), which define the outer circumference of the lower part 102 and 102, respectively. the upper portions 103 of the side frame 100. The models may also partially define one or more paths 540 for supplying and distributing molten material within the mold 500. This path or paths 540 for supplying material may preferably be located in the central region of the mold 500. which allows the molten material to be evenly distributed throughout the mold 500. The material supply paths 540 may be located, for example, in the area of the mold 500 that defines the bogie cradle housing opening 110 that is formed in the side frame 100.

Models (not shown) also define a shaped section 520 to form an axle 140 defined by the axle box on the side frame 100. In known molding methods, these models do not define details of the dimension 140 defined by the axle box. Instead, a core having the shape generally of the inner region of the ridge 140 defined by the axle bearing housing is inserted into the mold before casting. However, the cores tend to change position during the casting process, resulting in a casting with inaccurate dimensions and crevices that need to be removed.

The above model and group of risers 535 can then be inserted into respective molding frames 525 and 526, which are intended to be filled with molding material 527. The risers 535 can be inserted into the top 510 of the mold. The risers 535 correspond to hollow cylindrical structures into which molten material is filled during the individual operations of the casting process. The risers 535 are located in the mold areas that correspond to the areas

-12 * »· ':>' r”: * «. ·. ·· * :. ··:« ······ ·· · ♦ ·· * ·· side frame with larger thicknesses that cool more slowly than other areas of the side frame. The bosses 535 act as reservoirs for molten material, which compensates for volume losses of molten material in areas where the material shrinks, thereby preventing shrinkage or cracking due to shrinkage, which could otherwise occur in areas where the side frame casting is thicker. to occur. Examples of risers 550 on the side frame casting 100 are further shown in Fig. 5B.

In carrying out the operations of known technological processes, specific locations requiring precise dosing of the material are generally not known. Therefore, relatively large risers (e.g., 6 inches or larger) are used to cover larger areas. In contrast, in the described preferred embodiments of the invention, it is possible to determine the specific location requiring accurate dosing of the material by means of the various analytical procedures described below. As a result, it is possible to use risers 435 that have a significantly smaller diameter (e.g., about 4 inches or less), thereby increasing casting economy. The heights of the risers can range from approximately 4 to 6 inches. In one preferred variant of the invention, less than 10% of the gross weight of the starting foundry material cast in the mold falls on the risers. This results in a more efficient use of foundry material.

The molding frames 525 and 526 are generally sized to follow a model shape that is different from the shape of the molding frames used in known casting processes. These molding frames are generally dimensioned to accommodate the largest cast object that is formed during the casting process. Thus, in known casting processes, the molding frame can be dimensioned, for example, to match the size of the bogie cradle or even a larger object. The molding frames 525 and 526 according to the preferred embodiments described with reference to Fig. 5A have, in contrast to known molding frames, a shape that generally follows the shape of the cast article. For example, the mold frames 525 and 526 shown in Fig. 5A have the general shape of the side frame 100. The maximum distance L 530 between the edge of the respective mold frame 525, 526 and the part of the model closest to such edge of the mold frame may be less than 2 inches. Such molding frames 525 and 526 minimize the amount of molding sand required to form the mold 500. The ratio of the amount of molding sand to the amount of molten material cast in the mold in subsequent process operations may be less than 5: 1, for example. This is an important consideration given that the mold 500 can only be used once during casting.

A molding material 527 is then placed in the molding frame 525, which is compacted around and above the model until the molding frame 525 is filled. The molding material is then withdrawn

or it aligns with the forming frame and is then allowed to cure. After the molding material 527 has hardened, the model is removed from the molding frame.

The molding material 527 may correspond in composition to a material containing a chemical or resin binder, such as phenolic urethane, instead of the raw sand-based material used in known casting processes. The material containing the chemical binder allows the creation of casting molds with higher precision and with finer details.

In order to facilitate the removal of the models (not shown), the sides of the respective cavities in the lower and upper halves of the mold 500 are formed with a bevel whose angle D 515 is 1 °, 3/4 ° or less. These bevels prevent damage to the mold 500 when the model is removed. The bevel angle of the casting mold then corresponds to the bevel angle D 305 of the sidewalls of the cast side frame 100. For most surfaces of the side frame 100, bevel formation will have only insignificant consequences. However, bevel angles that are greater than 1 ° cannot be tolerated in certain areas, such as the contact surfaces 115 and areas 140 defined by the axle bearing housings. A material containing a chemical or resin binder, such as phenolic urethane, facilitates the formation of mold sides with bevel angles of 1 ° or less, which cannot be achieved with raw sand-based materials that use bevel angles to prevent damage to the casting mold. size of 3 ° or more. In addition, when using molds made of raw sand materials, additional cores are required in the areas 140 to be defined by the axle bearing housings, which allow the flatness requirements to be complied with when forming these shaped elements. These cores cause large leaks and dimensional fluctuations between castings.

In block 405, a core assembly 545 is formed that defines the inner region of the side frame 100. It will be apparent from the illustration in Fig. 6 that the core assembly 545 may include one or more portions. Thus, the core assembly 545 may include, for example, a pair of cores 605 for the axle bearing housing and associated bore, a core 610 for the cradle, a core 615 for the spring carrier, a core 620 for the lower tension member, and a pair of cores 625 for the inner arms. Each of the axle box cores 605 defines the interior of the axle box on the side frame, from the end frame 101 (Fig. 1A) of the side frame to the inner end of the respective side frame web 120 (Fig. 1A). The axle bearing housing core 605 may define one or more marks that form holes in the side frame casting. For example, the first set of marks 630 may form holes in the ends of the axle bearing housing that correspond to the ends of the side frame. The second mark 632 may form holes in the diagonal tension members 141 (Fig. 1A) of the side frame. The third core 634 may form end openings 142 (Fig. 1A) in the side frame webs.

For example, a forming tool may be formed that defines the upper half and lower half of a given core. Molding sand is inserted into the thus formed core, which is allowed to harden. The core is then removed, exposing the cured core. The respective cores can be formed individually, as a whole or as a combination formed by individual cores and subunits. The respective cores can consist of two parts. For example, each of the cores (i.e., axle box core, bogie cradle core, etc.) may be formed of an upper part and a lower part, which are formed separately in separate cores (i.e., in the upper and lower molding tools). After curing, the parts thus formed can be joined. For example, the top and bottom of a given core may be glued together to form a unitary core.

In block 410, the core assembly 545 is inserted into a mold, after which the side frame 100 is cast. The core assembly 545 may be inserted, for example, in the bottom 505 of the mold 500. A mold top 510 may then be placed on the bottom 505 of the mold, which may be attached to the bottom 505 of the mold by means of clamps, yokes or similar means. In this connection, positioning elements can be formed in the bottom 505 of the mold as well as in the top 510 of the mold, which ensure precise alignment of the two mold parts.

After securing the respective parts of the casting mold 500 relative to each other, molten material, in particular molten steel, is poured into this mold through an opening in its top 510. The molten material then flows through the inlet system 540 and the entire mold 500 into the space between the mold 500 itself and the core assembly 545.

In block 415, the side frame casting 100 is removed from the mold 500 and subjected to finishing. In this case, for example, the contact surfaces 115 can be machined in order to remove parts of the residual bevel D 305 which have arisen as a result of the existence of the bevel D 515 of the casting mold. Other material may be removed. For example, the material collected in the risers 535 is removed. In some embodiments, the mold 500 is arranged to form a wedge-shaped depression or recess in the riser material immediately adjacent the surface of the side frame 100. This wedge-shaped recess or recess then allows the material of the risers to be removed by hammering instead of the time-consuming flame cutting used in known casting finishing processes.

It follows from the above description of the various processes that the side frames 100 can be manufactured with a minimum of waste material and with a low time requirement. For example, said molding frame arrangements minimize the amount of molding material required to form the mold 500. Smaller bosses mean that less material (i.e., solidified steel) must be removed during finishing. The precision of the casting mold allows for dimensional production

-15 exact parts of the side frame, for example the dimensions defined by the axle bearing housings.

As a result of these improvements, less than 10% of the material is removed during finishing.

In addition to these advantages, other advantages can be realized. As mentioned above, molding frames 525 and 526 are not required when casting the side frame 100. Thus, molding frames 525 and 526 can be used to mold new casting molds during casting of the side frame 100.

As also mentioned above, different analytical procedures can be used to accurately determine different dimensions. To achieve tighter tolerances than those commonly achieved using raw sand molds or molding materials containing chemical or resin binders, such as phenolic urethane, an iterative casting and three-dimensional scanning process is used to measure critical dimensions and monitor dimensional instability. . This method can be used throughout the production process of cores, models, cores, top and bottom of the mold and the final casting. Due to the possibility of performing accurate measurements at each step of the production process, the shrinkage rates in all three directions (i.e. in the vertical, longitudinal and transverse directions) as well as the boron and core courses during solidification of the casting are known.

In one variant of the implementation of this method, the scanning can be performed by means of a three-dimensional point field sensor, for example by means of a scanning device Z Scanner, a Faro Laser Scanner or similar devices. Data obtained from three-dimensional point fields can be analyzed using software such as Geomagic®, Cam2® or Solidworks® to measure and compare tooling, cores and finished parts. The results of these comparisons can then be used to perform calculations of the actual shrinkage of the castings, which is usually expressed as a percentage. A typical shrinkage allowance in the production of carbon steel casting models can be about 1.56%. This typical shrinkage allowance is inaccurate and varies depending on the complexity of the cast shape. In some cases, the shrinkage allowance can be up to 2%. For large castings, such as the side frame or the bogie cradle, this size range of the shrinkage allowance can result in differences in the dimensions of the castings of up to 0.5 and thus non-compliance with the permitted tolerances.

In the described variants of the invention, the actual shrinkage rates in the vertical, longitudinal and transverse directions were determined using the above procedure and taken into account in the dimensions of the tooling.

In addition to calculating the shrinkage of the casting as it cools, it is important to know the warping process of the cores and the mold during solidification of the casting. The ability to control the course of core warping and casting mold allows

-16 gaining control over achievable tolerance ranges. This can be achieved through a combination of molding materials and the geometry of the cores and the mold. For the critical dimensions of the side frame, which are the distance A 170 between the webs (Fig. 1B), the distance B 175 between the axle bearing housings (Fig. IB) and the spacing C 270 of the web wear plate bolts (Fig. 2A), shrinkage of the casting utilizes relief holes 550 (Fig. 5A), which are formed in the cores and casting mold. By forming the axle box housings directly in the mold instead of using outer cores, a tolerance of ± 0.038 can be achieved with the distance shown between the axle box centers. By adding a pair of symmetrical relief holes 550 to the core 610 for the cradle mounting hole (Fig. 6), these holes being centered at a distance of about 10.6 above the spring carrier and at a distance of about 2 from the facing surfaces of the frame webs. the distance between the frame webs, which is also ± 0.038. This means that dimensions A 170 and B 175 can be limited by a tolerance range of ± 0.038. In other words, the error of these dimensions can be within ± 0.038. In addition, it is possible to achieve a uniform pitch C 270 (Fig. 2A) of the bolt holes in all castings, thus allowing the production of castings with differences in spacing between the bolt holes 210 in the frame webs of ± 0.020. This means that the C 270 dimension can be limited by a tolerance range of ± 0.020. This precision in the location of the holes 210 allows the use of smaller cores to form these holes 210, which are then only 0.050 larger than the respective fasteners, thus making it possible to obtain more precisely matched screw connections.

In addition to determining the achieved range of manufacturing variations of the molds and cores, which is used to perform shrinkage and boron calculations, it is also possible to reduce the size of the stamps. The reduction of the clearance in the area of contact between the mark formed in the mold at the corresponding core protrusion limits the range of movement of the core during casting. The smaller range of motion of the core then allows to achieve more accurate wall thicknesses and tolerances of other dimensions of castings. In addition to increasing the accuracy of the casting mold and narrowing the tolerances of the tooling, it is possible to obtain the possibility of controlling the extent of the casting of the casting mold, thus minimizing fluctuations in the dimensions of the stamps. The clearance used in this process was 0.030, with the casting mold being 0.030 larger than the insert formed on the core, as illustrated by dimension F 561, which is shown in a section taken along line 555 (Fig. 5A). That is, the distance F 561 between the edge of the mark 630 and the portion of the mold that is closest to the mark 630 is about 0.030. This value can be converted to an achievable wall thickness tolerance E 560 (Fig. 5A) of the finished casting of ± 0.020. This further means that the wall thickness E 560 (Fig. 5A) can be limited by a tolerance range of ± 0.020.

-17 • · * · * *. ·. · · I:. · ·:

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Another advantage of said processes is that the final surface of the side frame casting has a lower roughness than castings produced by known casting processes. The smaller the surface roughness of the casting, the longer the fatigue life of the part. The above procedures facilitate machining of side frames with an effective surface roughness value of less than about 750 microinches, and a surface roughness of less than about 500 microinches is even achieved in the area of the axle bearing housings.

FIG. 7 shows an example of a cradle 700 that can be used in combination with a side frame 100 as part of a railway car chassis. The bogie cradle 700 includes a main body section 715 and first and second outer end sections 705. The section 715 defines a turret section 707 on which the rail car body rests. On the longitudinal side of the cradle 700, pairs of holes 725 for accommodating the brake device and relief holes 720 are defined. for the manufacture of a bogie cradle, as will be described in more detail below. The first and second outer end portions 705 are arranged to allow connection to a pair of side frames 100. Specifically, each outer end portion 705 is located within a cradle mounting hole 110 that is formed in the side frame 100 and defines a pair of side support rails 706. , which are located below the respective bearing surfaces of the railway car body. Inside the cradle receiving hole 110, a group of springs is located below the outer end sections 705.

Each outer end section 705 includes a pair of friction shoe recesses 710. The surfaces of the respective friction shoe recesses 710 are known to be a critical area of the chassis cradle 700 in terms of finishing, as the friction shoe recesses 710 are arranged to abut the wear plates 135 and interact with these wear plates 135 so that these the elements work together as the shock absorbers described above. Friction feet in the form of wedges are mounted in the recess for the friction feet, which abut the wear plates arranged on the frame webs and slide along their surface.

It follows from the above description that the main body section 715 of the chassis cradle 700 defines a pair of holes 725 for accommodating a brake device, which are arranged to allow the use of brake equipment. These holes also act as marks for the core mold for the main body.

The chassis cradle 700 may be formed in a manner similar to the method of forming the side frame 100. The top and bottom of the mold may be formed, for example, from

A foundry molding material that contains a chemical or resin binder, such as phenolic urethane. The models that define the outer surfaces of the respective upper and lower parts of the cast cradle 700 of the chassis can also be used to form the respective cavities in the top and bottom of the mold. The bevel angles of the sides of the models can be 1 ° or less. As with the side frame, the molds used to form the mold can be sized to follow the shape of the model that defines the casting of the bogie cradle. The molding frame, which is defined in this way, minimizes the amount of molding material required to cast the bogie cradle. In some embodiments, the ratio of the amount of molding sand to the amount of molten material cast into the mold in subsequent process operations may be less than, for example, 3: 1. This is an important circumstance, considering that casting molds can only be used once during casting.

The risers 805 (Fig. 8) can be located in strategic positions and at the same time dimensionally optimized to allow the supply of an optimal amount of additional material during solidification of the casting in order to prevent shrinkage or cracking due to shrinkage in critical areas of the cradle 700 casting. one or more paths 810 can be formed in the casting mold to feed the molten material and distribute it throughout the mold, and these paths may be located in areas of the mold that extend along the longitudinal axis of the cradle casting 700. Thus, for example, the paths 810 to The supply and distribution of molten material were formed in the area of the casting mold, which is intended to form holes 725 for accommodating the brake device and wedge elements 708 located on the inside of the cradle 700, as shown. The molten material supply paths 810 may advantageously be located in the central region of the casting mold, which results in an even distribution of the molten material throughout the casting volume of the cradle 700 during its casting. In known chassis cradle casting processes, the molten material, in contrast to the present invention, is fed to a respective casting mold in the outer end region 701. This results in uneven cooling of the material in the direction of the longitudinal plane of the chassis cradle. If the cradle mold material is cast in the region of its first end 701, the metal in the region of the opposite end of the cradle casting will cool faster than the metal in the region of said first end 701. The molding frames in which the bottom and top of the mold are formed removed as soon as the relevant parts of the mold have hardened.

FIG. 9A shows an example of the top 903 and bottom 902 of a mold 900 for casting a bogie cradle, the mold being in an open state. It is clear from the illustration that the dividing plane 905, which separates the respective mold halves, does not follow a line parallel to the edges of the top 903.

-19a of the bottom 902 of the mold, as in the case of known molds for casting bogie cradles, which is shown in Fig. 9A by the dashed line 901. Figs. 9B shows the relationship between the parting plane 905 and the cradle 700 cast in the mold 900. In the main body section 715 of the mold, the parting plane 905 is generally centered between the mold portions that define the openings 725 for the mounted brake device. Thus, the dividing plane 905 generally follows a path that is centered between the top and bottom of the cradle 700 casting. essentially inside the bottom of the mold. In other words, the dividing plane 905 does not pass through these friction foot recesses 710.

In known casting processes, the entire parting plane forms a plane which passes through the entire casting of the bogie cradle. For example, the dividing plane can extend between the end sections and can be centered inside these end sections so that it intersects the recesses for the friction shoes and passes through the upper parts of the openings for accommodating the brake device. In the case of green sand molds, said recesses are formed by means of cores, since this shape cannot be formed in any other way in this casting process.

The dividing plane arrangement according to the described preferred variants of the invention has several advantages over the known dividing plane arrangements. It is known, for example, that the upper and lower parts of the respective openings for accommodating the brake device are areas in which high internal stresses act. The location of the parting plane in the vicinity of such places, as in the case of known parting plane arrangements, makes the casting of the bogie cradle more prone to high internal stresses. In contrast, in the described preferred embodiments of the invention, the dividing plane 905 is located in the middle of the openings 725 for accommodating the brake device, where the values of the internal stresses are lower. The parting plane of the casting mold is also located at the same level as the parting planes of the cores. This makes it possible to obtain uniform sidewall thicknesses, thus promoting uniform cooling of the casting.

There is no need to perform any finishing treatment on the friction foot recess 710, because the dividing plane does not pass through these friction foot recesses 710. In known separating plane arrangements, this is generally formed by a planar surface which intersects the bogie cradle and passes through the central regions of the friction foot recesses. This may result in the need to carry out the finishing of the stumps remaining after the cores and the surrounding areas of the friction foot recesses. However, the dividing planes according to the described variant embodiment of the invention are arranged above the recesses 710 for the friction feet. That is, the friction shoe recesses 710 are formed either only at the top or only at the bottom of the mold. The friction shoe recess 710 includes both

-20 already mentioned, among the more critical areas of the cradle 700 of the chassis. Therefore, eliminating the need to perform their finishing operations is advantageous.

The cross-sectional thickness of the bogie cradle is more symmetrical with respect to the parting plane 905. It follows from the above description that models are used to form cavities in the top and bottom of the mold. Models are created with bevels that allow models to be removed from the mold. Bars are used to create cores that define the internal shapes of the chassis cradle. The two halves of the jambs meet in the region of the dividing plane, to which the bevel angles, which allow the core to be removed, are also related. Where the dividing plane of the core and the dividing plane of the mold itself do not coincide, uneven wall thicknesses occur. The displacement of the parting plane towards the upper part of the bogie cradle casting, as in the case of the known parting plane configurations, thus results in an uneven cross-sectional thickness of the bogie cradle casting. This uneven thickness then results in the need to supply additional material when casting the bogie cradle. This uneven thickness also prevents uniform cooling and can allow for excessive shrinkage and associated shrinkage. In order to prevent these shrinkages, large risers must be used from which the material fed to the critical sections is taken. On the contrary, the location of the dividing plane 905 according to the described variant embodiment of the invention allows the formation of a cradle 700 of the chassis with a wall thickness which is symmetrical with respect to the dividing plane 905, as shown by thicknesses Ti 1005 and T ₂ 1010 in Fig. 10A. This further minimizes the amount of material required to cast the chassis cradle 700 while allowing the casting to cool evenly throughout its volume. In some cases of practical use of this method of casting, it is then necessary to remove less than 15% of the material from the casting during the finishing of the bogie cradle. In addition, the uniform cooling rate throughout the volume of the casting allows the use of substantially smaller risers.

Another advantage of the arrangement of the dividing plane 905 according to the described variant embodiment of the invention is that this arrangement allows easy alignment of the top and bottom of the mold.

In known casting processes, the positioning elements, such as pins and openings, are arranged inside the upper and lower halves of the mold frame and thus allow the halves to be aligned with each other. However large the misalignment of the positioning elements results in incorrect alignment of the upper and lower parts of the bogie cradle castings. However, the described dividing plane 905, due to its geometry, is adapted so that the top and the bottom of the mold interlock in a manner which creates a self-contained effect by means of which the two mold halves are established. As a result, pins and bushings, i.e. elements for adjusting the relative position, are not known to maintain the mutual alignment of the top and bottom of the mold.

-21 from the prior art.

After the top and bottom of the mold are formed, one or more cores 1100 are formed which define the interior of the cradle 700 of the chassis. The cores 11, the description of which refers to Fig. 11, may be formed in the manner described above, which is performed in block 405. The cores 1100 may include an upper portion and a lower portion that together define substantially the entire interior of the chassis cradle 700. The cores may be embodied, for example, such that the one or more cores 1105 for the main body include an upper portion 1105a and a lower portion 1105b, which together define the entire inner region of the chassis cradle 700. In other practical applications, each of the main body core portions 1105a and 1105b may define a respective inner region in a direction from the center of the bogie cradle (i.e., from the center transverse planes that intersect the bogie cradle) to the inwardly directed wedge protrusions 709 (Fig. 7). located in the outer end sections 705 of the chassis elbow 700. The core body core portions 1105a and 1105b may also partially define an inner region between the inwardly directed wedge protrusions 709 and the end of the chassis cradle 700. Each of the main body core portions 1105a and 1105b may define first and second marks 1120 and 1115. The separate end cores 1110 may then define inner regions in the outer end sections 705 of the chassis cradle 700 that are not defined by the main body core portions 1105a and 1105b. . Thus, the end cores 1110 may be formed independently of the cores 1105 for the main body. The end cores 1110 may be attached to the cores 1105 of the main body in subsequent manufacturing operations, for example by means of an adhesive.

The procedures described above relating to the narrowing of the tolerances of the different dimensions of the side frame casting can also be applied to the chassis cradle casting. For critical chassis cradle dimensions, such as friction shoe recess angles N 1020 (Fig. 10B), friction shoe recess widths 1025 (Fig. 10B), and distances G 750 between inner and outer wedge protrusions (Fig. 9B), similar sub-procedures should be used to measure the true extent of core and casting warping. Taking this range into account when determining the dimensions of the tooling, tolerances of ± 0.5 ° can be achieved for finished castings at angles of N 1020 for friction feet and ± 0.063 ”for widths of M 1025 for recesses. In addition, the inner and outer wedge protrusions 708 and 709 (Fig. 9B) can be formed directly in the bogie casting molds (Fig. 9B), thereby reducing the tolerance distance G 750 between these wedge protrusions to ± 0.063 ".

The distance H 950 (Fig. 9C) between the respective chassis cradle core locks and those parts of the top and bottom of the mold which are closest to the surfaces of said marks can be adjusted with an accuracy of about 0.030 °.

Another advantage of these processes is that lower surface roughness values of the finished cast bogie cradle can be achieved than using known casting processes. The smaller the surface roughness of the casting, the longer the fatigue life of the part. The above procedures facilitate machining of side frames with an effective surface roughness value of less than about 750 microinches, with a surface roughness of less than about 500 microinches being achieved in the friction shoe recess area.

Although various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many other embodiments and practical uses may be practiced without departing from the scope of the appended claims. The various dimensions described above are to be construed as examples only, which means that they can be varied as needed. Therefore, it will be apparent to those of ordinary skill in the art that many other variations and practical applications are possible that do not depart from the scope of the claims. The described variants of the invention are therefore given only to facilitate the understanding of the claims, the scope of which is not limited by these variants.

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PATENT CLAIMS

Claims (9)

PATENT CLAIMS A method of manufacturing a railcar bogie cradle comprising a pair of friction shoe recesses arranged at respective ends so as to allow insertion of the cradle into cradle mounting holes formed in respective side frames, the method comprising: providing a bogie cradle model for forming the bottom and top of the mold, and providing one or more cores that define the inner region of the cast bogie cradle, wherein the bogie cradle model and the one or more cores are arranged such that the friction foot angle deviations are located in the range of about ± 0.5 °. The method of claim 1, wherein a surface roughness of the cast bogie cradle of less than 750 microinches is achieved. The method of claim 2, wherein the surface roughness of the pair of friction shoe recesses is achieved with an effective value of less than 500 microinches. The method of claim 1, wherein the bevel angle of the sidewall recess for the friction shoe of the cast bogie cradle is not greater than about% of a degree. The method of claim 1, wherein the bogie cradle model and the one or more cores are arranged such that the distance limits of the respective inner and outer wedge protrusions of the cast bogie cradle are in the range of about ± 0.063 inches. The method of claim 1, wherein the bevel angles of the respective inner and outer wedge protrusions are not greater than about% of a degree. A method of manufacturing a railcar bogie cradle, comprising a pair of friction shoe recesses arranged at respective ends so as to allow insertion of the cradle into cradle mounting holes formed in the side frames, the method comprising: providing a model of the bogie cradle to form the bottom and top of the mold, and providing one or more cores that define the inner region of the cast bogie cradle, C5006 19.2.2013 • · · * · · · 4k · * »··· ·» ····· »i í» t · ** ···· ·· «· 1 ·» At «O · Wherein the chassis cradle model and the one or more cores are arranged such that the width tolerance between the individual recesses forming the pair of friction shoe recesses is in the range of about ± 0.063 inches. A method of manufacturing a railcar bogie cradle, the method comprising: providing a bogie cradle model for forming the bottom and top of a mold, and providing one or more cores that define an inner region of a cast bogie cradle, wherein at least some of the cores define one or more marks for locating one or more cores within the bottom of the mold, and wherein the distance between the outer surface of the one or more marks and the bottom surface of the mold that is closest to the outer surface of the one or more marks is less than or equal to about 0.030 inches. The method of claim 8, wherein the chassis cradle model and the one or more cores are arranged such that the wall thickness variations of the cast chassis cradle are in the range of about ± 0.02 inches.