WO1998031907A1

WO1998031907A1 - Overhead door track

Info

Publication number: WO1998031907A1
Application number: PCT/US1998/000884
Authority: WO
Inventors: Carlos M. Ochoa
Original assignee: Ochoa Carlos M
Priority date: 1997-01-22
Filing date: 1998-01-20
Publication date: 1998-07-23
Also published as: AU5922098A

Abstract

A garage door support structure (200) having an open-section tubular bead formed on at least one edge, with the tubular bead having a cross-sectional diameter which is large enough to substantially change the characteristic failure mode normally associated with the unreinforced edge stress concentration for a conventional overhead door support structure. The tubular bead can be used on a door track (10) or on an angle beam (110) used to support the door track. The tubular bead is designed to spread out the edge stresses. The addition of the tubular bead has the effect of changing the conventional track failure mode of crimping or buckling at relatively lower roller loads due to an edge stress concentration near the applied roller load or in the section of maximum bending moment. The tubular bead serves to reinforce the edge such that the edge stress concentration is substantially reduced both in terms of the maximum stress and the actual gradient of stress near the edge.

Description

TITLE OF THE INVENTION Overhead Door Track

BACKGROUND OF THE INVENTION The present invention is in the field of support members or structures for supporting an overhead door. More specifically, the present invention applies to the door track in which the wheels of an overhead door rides, or to the angle beam which can be used to support the door track.

Structural strength and integrity in overhead door track structures is closely related to two factors. The first is failure initiation, which is the mechanism by which the failure sequence begins. The second is failure propagation, which is the sequence of events leading to failure of the structure.

In a conventional track, failure is associated with two fundamental regions of high stress. The first region is associated with failure initiation, and the second is associated with failure propagation. The first region is an inherently characteristic region of edge stress concentration at the "blade edge" nearest to the roller contact point. This edge stress concentration is characteristic of the overall cross-sectional geometry of the "trough" of the track in which the roller rides. The second region is located along a line where the plane of the blade edge intersects the plane of the surface on which the roller rides. In most commonly found overhead door sizes, this region is approximately one inch wide. This region is characterized by two stress peaks separated by a short distance along the line of roller travel. In most commonly found overhead door sizes, these two points are separated by approximately three- fourths of an inch, with one peak located symmetrically on either side of the point of roller contact.

Failure initiation in a conventional track depends upon yield occurring in a very localized region. This yielding permits an edge imperfection to be created in the form of a local out-of-plane deformation. The overall geometry and the stress pattern causes this imperfection to grow as a local "bulge" of the plane of the blade edge, in the direction away from the roller contact point. It is significant that this stress concentration is made worse by the presence of relatively small local imperfections, even those on the order of size of the thickness of the track itself. The existence of any edge imperfections in a conventional track has the effect of enhancing an already established process of failure initiation. Even the most perfect, smooth edge of conventional track will experience a very localized point of high stress gradient due to the characteristic edge stress concentration. Initiation of an edge "bulge" or "crimp" on a perfect smooth edge is nothing more than the creation of an edge imperfection that is large enough to grow or "propagate" easily. This is the established process. The existence of any prior imperfections serves to greatly add to the already existing failure initiation process. The importance of this lies in the fact that imperfections do not add linearly to the already present stress concentration, but serve to compound its effect.

These imperfections can be in the form of edge notches, waviness (in-plane or out-of-plane), local thickness variations, local residual stress variations, or variations in material yield strength. Where multiple imperfections occur together, they all compound together to further increase the stress concentration effect, and thus lower the roller load level at which failure initiates. Even imperfections on the order of the size of the thickness of the track can compound in this manner to reduce track load carrying capability.

In a conventional overhead door track, failure propagation follows failure initiation in the following manner. Once a local "bulge" initiates at the blade edge, in the direction away from the roller contact point, the existence of the second region of high stress enables crimping of the blade edge to propagate. The result is a triangular "tea pot spout" shape which is formed as the edge folds distinctly along two lines connecting the first region of high stress with each of the two peaks of the second region. This propagation can be described as a local "edge buckling" since it is an instability of the sheet at the edge. Once initiated, the propagation stage can occur quite rapidly.

It should be noted that the propagation process described here corresponds to the case of a roller which is not rolling, but stays in the same position on the track as the load is increased until failure is reached. Actual in-service failures which may involve moving rollers will display variations of this basic propagation mechanism. In this way, multiple edge crimps with softened, nondistinct folds as opposed to sharp ones may form as multiple failure sites initiate and grow to various extents under repeated loading during service. This process will continue until either a single dimple forms that is large enough to impede roller travel, or until significant local track deflections impede normal door operation. Alternatively, a line of dimples may form which may cause the roller to interact with adjacent dimples in such a way as to lead to "track rollout".

The object of the present invention is to provide an overhead door support structure consisting of one or more structural elements which eliminate the tendency toward edge failures in such structures.

BRIEF SUMMARY OF THE INVENTION

The present invention is a garage door support structure having a tubular bead, or edge curl, formed on at least one edge, with the tubular bead having a cross- sectional diameter which is large enough to substantially change the characteristic failure mode normally associated with the unreinforced edge stress concentration for a conventional overhead door support structure. For manufacturing ease, the tubular bead can preferably be an open-section bead, meaning that the sheet metal is formed in an almost complete curl, but the curl need not be closed at its outer edge, such as by welding. A closed section tubular bead would work equally well, at a slightly higher manufacturing cost. The tubular bead can be used on a door track or on an angle beam used to support the door track. The tubular bead has a section diameter of the same order of magnitude as the other dimensions of the support structure, such as the widths of flanges on the door track or angle beam, where the tubular bead is formed on one or more of the flanges. The tubular bead is designed to spread out the edge stresses. The addition of the tubular bead has the effect of changing the conventional track failure mode of crimping or buckling at relatively lower roller loads due to an edge stress concentration near the applied roller load or in the section of maximum bending moment. The tubular bead serves to reinforce the edge such that the edge stress concentration is substantially reduced both in terms of the maximum stress and the actual gradient of stress near the edge. The upper and lower edge curls are tubular features, preferably open-section, that are made by shaping the edges of overhead door track or attached angle beam cross-sections into an elliptical, preferably circular, cross-sectional shape. For the purpose of the present application, a circular cross-section is considered to be a special case of an elliptical cross-section. The term "characteristic diameter" referring to a constant diameter in the case of a circle, while other elliptical shapes will have major and minor diameters, with the major diameter being the "characteristic diameter". Even though some configurations of a slightly non-circular elliptical shape may be more desirable in some applications, the circular cross-section is generally preferable, because it is simpler to manufacture, while still achieving the desired benefits to a significant degree.

The novel features of this invention, as well as the invention itself, will be best understood from the attached drawings, taken along with the following description, in which similar reference characters refer to similar parts, and in which:

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a section view of an overhead door track according to the present invention;

Figure 2 is a section view of an angle beam according to the present invention; and

Figure 3 is a section view of an overhead door support assembly according to the present invention, combining a door track as shown in Figure 1 with an angle beam as shown in Figure 2.

DETAILED DESCRIPTION OF THE INVENTION For the present invention, the structural performance benefit of using edge curls consists of a fundamental change in failure mode, which permits the track or angle beam to sustain substantially higher loads, thus permitting the use of thinner materials. This allows a savings in weight, therefore saving material. For the angle beam, the structural benefit includes increased bending and torsional rigidity, especially in combination with a track according to the present invention, incorporating the edge curl features. Again, substantial weight and material savings are possible. This innovation represents a substantial cost savings for the track and angle beam, since material cost is a substantial portion of total manufacturing costs for overhead door hardware. The elliptical or circular open-section tubular shape or "edge curl" is contrasted to tubular sections of rectangular cross-sectional shapes, including folded edges, and to open-section tubular shapes of softened corner rectangular cross- sectional shapes in that the characteristic diameter will be defined in each of these other cases by the fold diameter or by the softened corner diameter nearest to the track edge, as opposed to the overall diameter of the edge curl section. It may be noted that in this context a rectangular cross-section with very softened corners is in effect an imperfect ellipse or circle. This contrast is important because it is only with a characteristic edge section diameter of the same order of magnitude as the other track dimensions that the characteristic failure mode of conventional track may be changed to a great extent in a favorable manner without introducing other failure modes that are similar to the original. In this important sense, the present edge curl is unique when contrasted to quasi-elliptical or quasi-circular cross-sections.

The quasi-elliptical or quasi-circular cross-sections, imperfect ellipses, and imperfect circles, in the form of rectangular cross-sections with very softened corners, are less than adequate. This is because the ability to address the failure mode is somewhat less than that of the elliptical cross-section, and because the susceptibility of these other shapes to manufacturing imperfections and to in-service induced imperfections, such as dents, are compromised. The characteristic diameter of the section defines the order of size of the imperfection that may cause failure to initiate, thus degrading structural performance.

The upper and lower edge curls are also unique tubular shapes in that they are designed to serve multiple roles simultaneously. This multifunctionality is important because each role is independently vital to the success of the product throughout its life, including manufacture, handling, storage, transportation, installation, and in- service performance. This successful multifunctionality is an important part of what makes the curl feature such a substantial innovation, and enables significant weight savings over conventional door track and angle beam structures, through the use of thinner materials. Finally, the tubular shape is unique in that it is a substantially new piece of structure that can be added to the general conventional track shape without any new joining operations. This is particularly true in the case of the preferably open-section tubular shape. This is accomplished by simply using a wider sheet stock to accommodate the added width that is dedicated to the edge curl. Nevertheless, adding a tubular bead structure to the track or angle beam edges is also encompassed within the spirit of the present invention. The new structure simultaneously addresses a host of important considerations related to overhead track performance such as manufacturing (accommodating edge non-uniformity), safety in handling(exposed edge roughness), stress concentrations, reliability (imperfection size sensitivity of the edge), and aesthetics (smooth appearance).

The manufacturing method for creating the edge curl geometry is consistent with conventional roll forming and stretch forming manufacturing methods that are commonly used for the manufacture of overhead door track. The edge curl itself is designed to accommodate slight dimensional width variations or imperfections in raw sheet metal stock that are on the order of 1/32 inch or less. This is important for the following reasons: 1. Safety in handling of the product throughout its life is greatly enhanced by concealing edge imperfections and roughness from exposure to personnel during subsequent handling. The edge curl thus simplifies achieving a product that can be handled safely during manufacture, transportation, installation, and service. 2. The edge curl permits a reduction in required manufacturing operations.

These operations include deburring and smoothing of the edges as well as monitoring the sheet roll stock for width uniformity and edge quality. The edge curl thus simplifies achieving a product that will have edge dimensional uniformity and an attractive, smooth appearance. 3. The overall structural strength and integrity implications of addressing sheet stock edge imperfections to achieve manufacturing or safety improvements. These improvements must be accomplished at little or no expense to structural performance. In this regard, the edge curl approach is successful from two different standpoints: a. The curl geometry places edge imperfections in a relatively low stress location (i.e. the portion of the edge curl closest to the roller contact surface). This is in contrast to conventional track where the sheet edge itself and any imperfections that remain on it (or any that are introduced later during subsequent handling) are positioned at the outer edge, which is where the highest in-service stresses occur, b. The characteristic stress concentration present in conventional track is addressed very effectively by the reinforcing presence of the curl. This stress concentration in conventional track is of tremendous importance because it is actually compounded by the presence of edge imperfections which themselves have a stress concentration effect. Overcoming not one but two stress concentration problems, along with rendering them unable to compound in the new track design, is of tremendous importance with far reaching structural weight saving implications. The edge curl is designed to spread out the track edge stresses of the edge that is nearest to the roller contact surface. The addition of the curl has the effect of changing the conventional track failure mode of crimping or buckling at relatively lower roller loads due to an edge stress concentration near the applied roller load or in the section of maximum bending moment. The curl does more than just place more material at the edge. It also serves to reinforce the edge, such that the edge stress concentration is substantially reduced both in terms of the maximum stress and the actual gradient of stress near the edge.

The presence of the edge curl, whether open or closed section, has three primary effects upon failure initiation. Each of these effects diminishes failure initiation factors in order to reinforce the edge against failure. The first effect is to spread the edge stresses out, in effect eliminating to a great extent the edge stress concentration. The "open section tube" form of the edge curl geometry is especially well suited for this task in that spreading stresses is characteristic of this geometry. In this way, the sheet edge crimping or buckling of the conventional track shape is fundamentally and effectively changed. This is because the initiation process of crimping or buckling at the edge of conventional track relies upon a very localized point of high stress gradient at the very edge in order to initiate.

The second effect is to make the edge insensitive to imperfections that are of the same order of size as the thickness of the sheet. This is characteristic of the "open section tube" geometry and the way that it spreads stresses, even in the presence of local imperfections. The modified edge, including the edge curl, is thus only sensitive to imperfections that are of the same order of size as the curl diameter itself. This is a substantial change in that larger imperfections are not only less common and thus fewer in number, but are also much easier to detect visually. The ability to detect the kinds of imperfections that lead to failure is of fundamental importance to product reliability, maintenance and safety concerns. The result is a substantially safer and more failure resistant product.

Finally, the third effect is that the curl geometry places sheet stock edge imperfections, such as in-plane or out-of-plane waviness or edge notches, in a relatively benign location. This location corresponds to the portion of the curl section geometry nearest to the roller contact surface, where it experiences relatively lower stresses as compared to the region farthest away from the roller contact surface. Thus, the curl permits some imperfections to remain without reducing structural performance, while achieving substantial positive impacts in other important product areas such as safety, reliability, maintenance, manufacturing and handling.

The curl geometry has the effect of spreading stresses out in the region of the edge near the point of roller contact on the track. This is important from three standpoints. The first is that the maximum stress is substantially reduced, thus increasing the load carrying capability of the same thickness track. The second is that the mechanism that existed for the first and second regions of high stress to link up and thus propagate, has been substantially eliminated by spreading out the peak stresses of the region affected. This has the effect of inducing a much greater resistance to failure. This is because the stresses of the high stress region of conventional track are now spread over a region that is larger than the commonly found 3/4 inch characteristic dimension. It is significant to note that this effect is enabled by the fact that the edge curl diameter which will be used in many common overhead door applications is 3/16 inch, which is of the same order of size as each of the following dimensions which will be appropriate for a large number of commonly found doors: the track trough dimension (about 1/2 inch diameter), the blade edge length (about 1/2 inch), and the characteristic dimension of the propagated failure of a conventional track, which is about 3/4 inch. This curl geometry combines with the characteristic behavior of open or closed section tubes to spread stresses over the affected region, especially near the failure stress. This mechanism is discussed in more detail below. It is important to contrast the edge curl approach against other possible reinforcement approaches by noting that the dimensional order of size effect described above for the curl can not be achieved by simply folding the edge over, either once or multiple times, because in this case the characteristic dimension will be defined by the fold edge diameter and not by the length of overlap of the fold. This is because the overlap direction is transverse to the edge and quickly moves out of the peak stress region, and because in this case the edge fold diameter defines the maximum distance over which the edge stresses may be effectively spread.

The edge failure mode of a design incorporating the present invention is governed by the failure mode of the tubular bead, or edge curl. This failure mode is typical of tubes and beams, in bending, where local buckling or crimping of the curl itself may be avoided by choosing the ratio of curl diameter to wall thickness to be less than 50 for steel alloys. The curl which will be suitable for most commonly found door sizes has been sized at 3/16 inch diameter, which is consistent with this criterion, enabling greater load carrying capability. Thus, the curled edge will develop a modulus of rupture exceeding the ultimate tensile strength for the full range of track material thicknesses that are typically used for overhead doors, while remaining fully retrofitable with other associated hardware in terms of thickness and clearance requirements. This design advantage is over and above the substantial reduction in edge stress concentration.

The resulting design is more robust in that track edge crimping occurs only at much higher loads. It is also more robust because the order of magnitude of minimum imperfection size to which the edge is sensitive has been effectively changed to the order of size of the curl diameter. This favorable synergistic combination of resistance to crimping and relative insensitivity to edge imperfections has the same degree of compounding advantage as the conventional track's compounding disadvantage of low resistance to crimping combined with sensitivity to relatively small edge imperfections. Of further advantage is that the minimum size of detrimental imperfections which may significantly contribute to the degradation of structural performance has been greatly increased. These minimum size imperfections are now of a size that may be detected much more easily by the naked eye during visual inspection at any time during the life of the product for quality control, field maintenance, or safety purposes.

Finally, it may be noted that by increasing the minimum size of detrimental imperfections which may significantly contribute to the degradation of structural performance, the total number of imperfections that may affect the structure has been greatly reduced, from a statistical standpoint. This has the effect of commensurably increasing structural reliability.

The upper and lower edge curls help the track and angle beam sections to more effectively resist bending and torsion due to roller loads. This is because of the placement of the curl relative to the centroid of the structure, and the ability of the curl to spread stresses, since it is placed in positions associated with maximum structural stresses.

The contoured lower section minimizes the moment arm of applied roller loads with respect to the geometric plane of the vertical edge of track section, while maintaining required clearances for smooth operation of the roller. In addition, as the local track section deflects slightly under load, the lower section shape actually deforms in a way that diminishes the moment arm, thereby improving performance.

The invention enables the track gage thickness to be reduced by an amount up to 40%. This enables a weight savings of up to 33% for typical overhead door applications, while preserving normal operational and structural capability. In addition, the track is retrofitable to conventional overhead door hardware.

When the edge curl feature is applied to the angle beam which is commonly attached to overhead door horizontal track, an additional increment of weight savings on the angle beam is achievable. When this increment is combined with the weight savings achieved with the new track design, a total weight savings of up to 40%> may be achieved while preserving normal operational and structural capability. In this case the track thickness remains the same as for the case where the new track design might be combined with a conventional angle beam. The following description of a preferred embodiment of the present invention will incorporate dimensions which are representative of the dimensions which will be appropriate for most commonly found overhead door sizes. Recitation of these dimensions is not intended to be limiting, except to the extent that the dimensions reflect relative ratios between the sizes of various elements of the invention, as will be explained where appropriate.

As shown in Figure 1, a door track 10 incorporating the present invention consists of a first track flange 12, a second track flange 14 substantially orthogonal to the first track flange 12, and one or more open-section tubular beads or edge curls 20, 22. It should be noted that a garage door track 10 typically has a vertical portion alongside the door opening, and a horizontal portion extending from the top of the door opening. This allows the door track 10 to guide the door rollers (not shown) during travel of the door alongside the door opening and out away from the door opening. In the vertical portion of the door track 10, the first flange 12 will be substantially vertical, but in the horizontal portion of the door track 10, the first flange 12 will be substantially horizontal. The second flange 14 will be substantially vertical in both the vertical and horizontal portions of the door track 10. At all points along the door track 10, the first flange 12 will be substantially parallel to supported portions of the overhead door, while the second flange 14 will be substantially orthogonal to supported portions of the overhead door. The door track 10 can be constructed of a sheet metal, such as steel.

The first flange 12 is joined to the second flange 14 along a common edge, with both flanges 12, 14, preferably being formed from a single piece of sheet metal. The second flange 14 can incorporate a first section 16 orthogonal to the first flange 12, and a trough 18 formed along the free edge of the first section 16. The first tubular bead 20 can be formed as a part of, or added to, the free edge of the first flange 12, and a second tubular bead 22 can be formed on or added to the free edge of the second flange 14, specifically on the free edge of the trough 18. The illustrated example of the first tubular bead 20, being of the open-section type, has a gap 24 between the free edge of the bead 20 and the first flange 12. Similarly, the second tubular bead 22 shown, being of the open-section type, has a gap 26 between the free edge of the bead 22 and the second flange 14. The tubular beads 20, 22 are elliptical in cross-section, with the cross-section of the specific beads shown here being a special case of the ellipse, namely circular.

In a representative door track 10 suitable for most commonly found overhead door applications, the first flange 12 will have a width 32 on the order of 1 inch, while the second flange 14, including the trough 18, will have an overall width 34 on the order of 2 inches. The first section 16 of the second flange 14 in such a representative door track 10 will have a width on the order of 1 1/2 inches. The common edge between the first and second flanges 12, 14 will have a radius on the order of 1/8 inch.

The trough 18 has a first wall 36 adjoining the first section 16 of the second flange 14, a second wall 38 opposite the first wall 36, and a rounded bottom contour 39 therebetween. The rounded contour 39 of the bottom of the trough 18 will have a radius 40 on the order of 1/4 inch. The horizontal distance between the lowermost portion of the bottom contour 39 and the plane of the first section 16 of the second flange 14 is on the order of 3/8 inch. The horizontal distance between the second bead 22 and the first wall 36 of the trough 18 is a minimum of 1 7/16 inch, with this gap being centered over the lowermost portion of the bottom contour 39. The second wall

38 of the trough 18 lies in a plane at an acute angle with the plane of the first section

16 of the second flange 14. This acute angle can be on the order of a 45° angle.

In such a representative door track 10, the first tubular bead 20 will have a characteristic diameter 28 of 3/16 inch. Similarly, the second tubular bead 22 will have a characteristic diameter 30 of 3/16 inch. If a non-circular elliptical shape were to be used, the characteristic diameter would be the major diameter of the ellipse, but it would still be sized on the order of 3/16 inch. For steel alloys, this characteristic diameter is no more than 50 times as great as the thickness of the sheet metal of which the respective flange 12, 14 is formed. Significantly, the characteristic diameter of each tubular bead 20, 22 is of the same order of magnitude as the width of the flange 12, 14 on which the bead 20, 22 is formed.

As shown in Figure 2, an angle beam 110 incorporating the present invention consists of a first beam flange 112, a second beam flange 114 substantially orthogonal to the first beam flange 112, and one or more open-section tubular beads or edge curls 120, 122. It should be noted that a garage door angle beam 110 typically extends horizontally from the top of the door opening. This allows the angle beam 110 to support the portion of the door track 10 extending horizontally away from the door opening. In such a horizontal angle beam 110, the first flange 112 will be substantially horizontal. The second flange 114 will be substantially vertical. At all points along the angle beam 110, the first flange 112 will be substantially parallel to supported portions of the overhead door, while the second flange 114 will be substantially orthogonal to supported portions of the overhead door. The angle beam 110 can be constructed of a sheet metal, such as steel.

The first flange 112 is joined to the second flange 114 along a common edge, with both flanges 112, 114, preferably being formed from a single piece of sheet metal. The first tubular bead 120 can be formed as a part of, or added to, the free edge of the first flange 112, and a second tubular bead 122 can be formed on or added to the free edge of the second flange 114. The first tubular bead 120 shown here, being of the open-section type, has a gap 124 between the free edge of the bead 120 and the first flange 112. Similarly, the illustrated second tubular bead 122, being of the open- section type, has a gap 126 between the free edge of the bead 122 and the second flange 114. The tubular beads 120, 122 are elliptical in cross-section, with the cross- section of the specific beads shown here being a special case of the ellipse, namely circular.

In a representative angle beam 110 suitable for most commonly found overhead door applications, the first flange 112 will have a width 132 on the order of

1 inch, while the second flange 114 will have a width on the order of 1 1/2 inches.

The common edge between the first and second flanges 112, 114 can have a radius on the order of 1/8 inch, or it can be a sharp angle as shown.

In such a representative angle beam 110, the first tubular bead 120 will have a characteristic diameter 128 of 3/16 inch. Similarly, the second tubular bead 122 will have a characteristic diameter 130 of 3/16 inch. If a non-circular elliptical shape were to be used, the characteristic diameter would be the major diameter of the ellipse, but it would still be sized on the order of 3/16 inch. For steel alloys, this characteristic diameter is no more than 50 times as great as the thickness of the sheet metal of which the respective flange 112, 114 is formed. Significantly, the characteristic diameter of each tubular bead 120, 122 is of the same order of magnitude as the width of the flange 112, 114 on which the bead 120, 122 is formed. As shown in Figure 3, the door track 10 incorporating the present invention can be attached to and supported by the angle beam 110 incorporating the present invention, to form an overhead door support assembly 200.

While the particular invention as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages hereinbefore stated, it is to be understood that this disclosure is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended other than as described in the appended claims.

Claims

CLAIMS I claim:

1. An elongated overhead door support member, comprising: a first flange; a second flange joined to said first flange along a common edge; and a tubular bead on a free edge of at least one of said flanges, said tubular bead having an elliptical cross section, said elliptical cross section having a characteristic diameter of the same order of magnitude as the width of said flange on which said tubular bead is formed, said elliptical cross section having a characteristic diameter no greater than 50 times the thickness of said flange on which said tubular bead is formed.

2. An elongated overhead door support member as recited in claim 1, wherein said support member is configured and oriented for supporting at least one wheel of an overhead door.

3. An elongated overhead door support member as recited in claim 2, wherein said support member is a door track for supporting and guiding at least one wheel of an overhead door, said second flange comprising: a first section orthogonal to said first flange; and a trough formed on a free edge of said first section for receiving a wheel of an overhead door, at least one said tubular bead being formed on a free edge of said trough.

4. An elongated overhead door support member as recited in claim 3, wherein: said first flange extends in a direction substantially parallel to an overhead door being supported by said door track; and said second flange extends in a direction substantially orthogonal to an overhead door being supported by said door track.

5. An elongated overhead door support member as recited in claim 4, wherein said trough comprises: a substantially straight first wall joining said first section of said second flange, said first wall being oriented oblique to said first section of said second flange; a rounded cross sectional contour at the bottom of said trough for receiving a wheel of an overhead door; and a substantially straight second wall, said tubular bead being formed on a free edge of said second wall.

6. An elongated overhead door support member as recited in claim 5, wherein said elliptical cross section of said tubular bead has a characteristic diameter of the same order of magnitude as the width of said second wall.

7. An elongated overhead door support member as recited in claim 5, wherein said second wall of said trough lies in a plane forming an acute angle with the plane of said first section of said second flange.

8. An elongated overhead door support member as recited in claim 2, wherein: said support member is an angle beam for supporting a door track; and a tubular bead is formed on each of said flanges.

9. An elongated overhead door support member as recited in claim 8, wherein: said first flange extends in a direction substantially parallel to an overhead door being supported by said angle beam; and said second flange extends in a direction substantially orthogonal to an overhead door being supported by said angle beam.

10. An elongated overhead door support member as recited in claim 8, wherein said elliptical cross section of each said tubular bead has a characteristic diameter of the same order of magnitude as the width of said flange on which said tubular bead is formed.

11. An elongated overhead door support member as recited in claim 1, wherein said tubular bead is an open-section tubular bead.

12. An elongated overhead door support track for supporting and guiding at least one wheel of an overhead door, comprising: a first flange; a second flange joined to said first flange along a common edge; a trough on said second flange for receiving a wheel of an overhead door, said trough having an inner wall adjacent to said second flange, said trough having an outer wall, said trough having a rounded bottom contour between said inner and outer walls; a first tubular bead on a free edge of said first flange, said tubular bead having an elliptical cross section, said elliptical cross section having a characteristic diameter of the same order of magnitude as the width of said first flange, said elliptical cross section having a diameter no greater than 50 times the thickness of said first flange; and a second tubular bead on a free edge of said outer wall of said trough, said tubular bead having an elliptical cross section, said elliptical cross section having a characteristic diameter of the same order of magnitude as the width of said outer wall of said trough, said elliptical cross section having a characteristic diameter no greater than 50 times the thickness of said outer wall of said trough.

13. An elongated overhead door support track as recited in claim 12, wherein: said first flange extends in a direction substantially parallel to an overhead door being supported by said door support track; and said second flange extends in a direction substantially orthogonal to an overhead door being supported by said door support track.

14. An elongated overhead door support track as recited in claim 12, wherein: said inner wall is a substantially straight wall joining said second flange, said inner wall being oriented obliquely relative to said second flange; and said outer wall is a substantially straight wall lying in a plane forming an acute angle with the plane of said second flange.

15. An overhead door support assembly, comprising: a door track for supporting and guiding at least one wheel of an overhead door, said door track comprising: a first track flange; a second track flange joined to said first track flange along a common edge; a trough on said second track flange for receiving a wheel of an overhead door; and a first tubular bead on a free edge of said trough, said first tubular bead having an elliptical cross section, said elliptical cross section having a characteristic diameter of the same order of magnitude as the width of said second track flange, said circular cross section having a diameter no greater than 50 times the thickness of said trough; an angle beam fastened to and supporting said door track, said angle beam comprising: a first beam flange; a second beam flange joined to said first beam flange along a common edge; and an additional tubular bead on a free edge of at least one of said beam flanges, each said additional tubular bead having an elliptical cross section, said elliptical cross section having a characteristic diameter of the same order of magnitude as the width of said beam flange on which said additional tubular bead is formed, said elliptical cross section having a diameter no greater than 50 times the thickness of said beam flange on which said additional tubular bead is formed.

16. An overhead door support assembly as recited in claim 15, wherein: said first track flange and said first beam flange extend in a direction substantially parallel to an overhead door being supported by said support assembly; and said second track flange and said second beam flange extend in a direction substantially orthogonal to an overhead door being supported by said support assembly.

17. An overhead door support assembly as recited in claim 15, wherein said trough comprises: a substantially straight first wall joining said second track flange, said straight wall being oriented oblique to said second track flange; a rounded cross sectional contour at the bottom of said trough for receiving a wheel of an overhead door; and a substantially straight second wall, said tubular bead being formed on a free edge of said second wall.

18. An overhead door support assembly as recited in claim 17, wherein said elliptical cross section of said first tubular bead has a characteristic diameter of the same order of magnitude as the width of said second wall of said trough.

19. An overhead door support assembly as recited in claim 17, wherein said second wall of said trough lies in a plane forming an acute angle with the plane of said second track flange.

20. An overhead door support assembly as recited in claim 15, wherein each said tubular bead is an open-section tubular bead.