TECHNICAL FIELD OF THE INVENTION
- BACKGROUND OF THE INVENTION
The present invention relates generally to the field of railcars, and more particularly to a railcar draftsill and method of forming a railcar draftsill.
A railcar may have a draftsill at each end of its box frame for accepting couplers. Draftsills are currently built by welding together two rolled structural shapes, such as Z-sections, or by casting.
Manufacturing difficulties exist in producing draftsills of these designs. Current draftsill fabrication requires special welding considerations to accommodate distortion from welding. In addition, the grade of material for the structural shapes is limited. Also, the weight of the draftsill is limited by the properties of the available structural shapes.
- SUMMARY OF THE INVENTION
Draftsills that are cast require extensive gauging and finishing or machining, all of which are cost-prohibitive. In addition, the grade of material for cast sections is subject to casting restrictions, such as feeding and subsequent heat treating to develop strength. Also, the minimum weight of the draftsill is limited by minimum section sizes required to pour castings of acceptable solidity.
According to one embodiment of the invention, a method of forming a sill of a railcar draftsill includes providing a single plate of material having predetermined dimensions, bending the single plate to form a first leg, bending the single plate to form a second leg and a web disposed between the first and second legs, bending the first leg to form a first flange, and bending the second leg to form a second flange. The single plate of material may be formed into the desired configuration according to a method having a single forming step.
Embodiments of the invention provide a number of technical advantages. Embodiments of the invention may include all, some, or none of these advantages. A draftsill manufactured according to the teachings of one embodiment of the present invention may be more efficiently designed because both the type of material and the thickness of material can be specified with fewer restrictions than structural sections. This significantly reduces the weight of a draftsill, strengthens the draftsill, and reduces cost. In addition, dimensions and tolerances can be tightened and met more easily because of less welding distortion. No full-length, full-penetration weld is required for the sill, which reduces distortion and cost.
BRIEF DESCRIPTION OF THE DRAWINGS
Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.
For a more complete understanding of the invention, and for further features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a bottom plan view of a draftsill coupled to a railcar box frame according to one embodiment of the present invention;
FIG. 2 is an exploded, bottom perspective view of the draftsill of FIG. 1;
FIGS. 3A through 3C illustrate one method of forming a sill of the draftsill of FIGS. 1 and 2 according to one embodiment of the present invention; and
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION
FIG. 4 illustrates another method of forming a sill of the draftsill of FIGS. 1 and 2 in accordance with one embodiment of the present invention.
Example embodiments of the present invention and their advantages are best understood by referring to FIGS. 1 through 4 of the drawings, in which like numerals refer to like parts.
FIG. 1 is a bottom plan view of a draftsill 200 coupled to a box frame 100 of a railcar 102 according to one embodiment of the present invention. Railcar 102, which may be any suitable vehicle that rides along rails, has draftsills 200 coupled at each end of box frame 100; however, only one draftsill 200 is shown for description purposes. Draftsill 200 may be coupled to box frame 100 in any suitable manner, such as welding.
FIG. 2 is an exploded, bottom perspective view of draftsill 200. The general function of draftsill 200 is to aid in coupling railcars 102 together. Draftsill 200 includes a sill 202, a striker face assembly 204, a pair of front draftstops 206 (only one is shown), a pair of rear draftstops 208 (only one is shown), and a center plate 210.
According to the teachings of the present invention, sill 202 is formed from a single plate of material 212. Forming sill 202 from plate of material 212 eliminates the need of having to weld together plate sections, angles, or other structural sections, such as Z-sections. Eliminating welding saves time and money, and also allows a design engineer to specify tighter dimensions and tolerances. In addition, forming sill 202 from plate of material 212 eliminates having to cast sill 202, which also saves time and money associated with casting. For example, cast sections require extensive gauging and finishing operations, which are cost-prohibitive. In addition, the strength and toughness of a sill formed from a plate material rather than a casting is much greater. In one embodiment, plate of material 212 is formed from a structural steel (e.g., ASTM A572, A1, and A36) having a thickness between approximately one-quarter inch and one inch. However, plate of material 212 may be formed from different suitable materials and different thicknesses, depending upon the application.
Sill 202 includes a web 214, a first leg 216, a second leg 218, a first flange 220, a second flange 222, a plurality of holes 224, and a plurality of slots 226. Although sill 202 may be formed in various shapes, the illustrated embodiment is an example configuration for sill 202. In one embodiment, draftsill 200 is approximately five foot in length; however, other suitable lengths for draftsill 200 may be utilized. In the illustrated embodiment, first leg 216 and second leg 218 extend outwardly from web 214 such that substantially 90° angles are formed between the plane of web 214 and the planes of first and second legs 216, 218, respectively. Both first leg 216 and second leg 218 may be any suitable height 217 and their thickness is governed by the thickness of plate of material 212. Similarly, first flange 220 is formed outwardly from first leg 216 and second flange 222 is formed outwardly from second leg 218 such that substantially 90° angles are formed between the planes of each flange 220, 222 and the respective planes of legs 216, 218. Both first flange 220 and second flange 222 may be any suitable width 221 and their thickness is governed by the thickness of plate of material 212. As described below, other suitable angles may be formed between the above described elements of sill 202.
A plurality of holes 224 are formed in first flange 220 and second flange 222. Holes 224, which may be any suitable diameter, may be located in other suitable locations on sill 202. In addition, there may be any number of holes 224. Holes 224 function to accept cross-members (not shown) for structural stability for draftsill 200 and for additional support for a coupler's draft gear.
Slots 226, which may be any suitable size and shape, function to accept front draftstops 206 and/or rear draftstops 208. Slots 226 facilitate the coupling of front draftstops 206 and rear draftstops 208 to sill 202. This coupling may be accomplished by welding.
Striker face assembly 204 couples to one end of sill 202 and flnctions to accept a coupler of an adjacent railcar 102. Striker face assembly 204 may be any suitable size and shape and may be, in some embodiments, combined with front draftstops 206 and cast as one unit. Striker face assembly 204 is coupled to sill 202 in any suitable manner such as, for example, by welding.
Front draftstops 206 and rear draftstops 208 function to retain a draft gear of a coupler that is inserted through striker face assembly 204 into sill 202. Only one front draftstop 206 and one rear draftstop 208 are shown to be coupled to first leg 216 for clarity purposes. Preferably, an additional front draftstop 206 and an additional rear draftstop 208 exist on the inside of second leg 218. Any suitable front draftstops 206 and rear draftstops 208 may be utilized in accordance with the present invention and may be coupled to sill 202 in any suitable manner, such as by welding.
Center plate 210 is coupled to sill 202 in any suitable manner such as, for example, by welding. An aperture 211 functions to accept a pin existing on a truck assembly (not shown) of railcar 102. Center plate 210 may be any suitable size and shape.
Now that the details of one embodiment of draftsill 200 have been described, one method of forming draftsill 200 is described below in conjunction with FIGS. 3A through 3C. An additional method of forming draftsill 200 is also described below in conjunction with FIG. 4.
FIG. 3A illustrates plate of material 212 having holes 224 and slots 226 formed therein. Having holes 224 and slots 226 formed in plate of material 212 before forming sill 202 eliminates the need of having to drill or form holes 224 or 226 after the forming of sill 202. This saves considerable time and money because it is easier to work with plate of material 212 as a planar element as opposed to an element that has already been formed with angles. However, holes 224 and slots 226 may be formed at any time during the forming of sill 202. As described above, plate of material 212, in one embodiment, is structural steel; however, other suitable materials that are available in plate form may also be used. Plate of material 212 may be of any suitable thickness; however, a preferred thickness for plate of material 212 is approximately one-quarter inch to one inch. As illustrated in FIG. 3A, plate of material 212 is cut according to predetermined dimensions. The predetermined dimensions are such that after bending operations are carried out on plate of material 212, as described below, plate of material 212 will be in the final form of sill 202 without having to do any subsequent finishing operations. Eliminating finishing or follow-up operations saves considerable time and money. Also, full-length, full-penetration welding is eliminated, which results in many advantages as described above.
FIG. 3B illustrates bending plate of material 212 to form a first leg 216 and a second leg 218. The forming of first leg 216 and second leg 218 also results in the forming of web 214, which is disposed between first leg 216 and second leg 218 as illustrated. As described above, in one embodiment, an angle of approximately 90° is formed between both first leg 216 and web 214, and second leg 218 and web 214. Other suitable angles may be formed between legs 216, 218 and web 214. Any suitable forming operation may be utilized to form legs 216, 218. For example, a press or press brake may be utilized. In addition, legs 216, 218 may be cold formed, warm formed, or hot formed, depending on the type of material of plate of material 212 and its thickness.
FIG. 3C illustrates the bending of first leg 216 to form first flange 220 and the bending of second leg 218 to form second flange 222. As described above, a substantially 90° angle is formed between first flange 220 and first leg 216 and also between second flange 222 and second leg 218. However, other suitable angles may be utilized depending upon the final desired configuration of sill 202. Similar to the bending of legs 216, 218, flanges 220, 222 may be formed using any suitable forming operation, such as by using a press or press brake. In addition, flanges 220 and 222 may be cold formed, warm formed, or hot formed, depending on the type of material of plate of material 212 and its thickness. After flanges 220 and 222 are formed, this ends one method of forming sill 202. No other finishing operations are needed, which saves considerable time and money. In addition, dimensions and tolerances of sill 202 may be more tightly specified and may be met more easily by forming sill 202 out of a single plate of material 212. Sill 202 as illustrated in FIG. 3C will then be in its final form (for example, as that shown in FIG. 2).
FIG. 4 illustrates another method of forming sill 202 of draftsill 200. In the illustrated embodiment, sill 202 is formed in a one-step forming operation by sandwiching plate of material 212 between a top surface of a female die 400 and a bottom surface of a male die 402. Female die 400 and male die 402 may be coupled to any suitable press. Other suitable forming operations may be utilized to form sill 202 to its final non-planar configuration in a one-step forming operation. In the method shown in FIG. 4, sill 202 is hot formed; however, depending on its thickness and material type, sill 202 may also be warm formed or cold formed. As in the embodiment illustrated in FIGS. 3A through 3C, holes 224 and slots 226 may be formed in plate of material 212 before or after the forming step illustrated in FIG. 4 is performed. Once the forming step is finished, sill 202 takes on its final non-planar configuration, such as that shown in FIG. 2. Again, no further finishing operations are required. However, other finishing operations may be performed, such as heat treating and surface treating.
Although embodiments of the invention and their advantages are described in detail, a person skilled in the art could make various alterations, additions, and omissions without departing from the spirit and scope of the present invention as defined by the appended claims.