Patent Application
20120273539
The invention generally relates to a support structure for use in a vehicle, and a method of manufacturing the support structure.
Motor vehicles, including but not limited to passenger cars and light trucks, may include several different support structures for supporting various components of the vehicle. An example of such a support structure is an instrument panel support beam. These support structures may be manufactured completely from a metal, and include a primary tubular support to which various different support plates and/or mounts are welded. Alternatively, in order to reduce weight of the vehicle, the various different support plates and/or mounts may be overcast onto the tubular support from a lightweight material. For example, the tubular support may include a simple round cylindrical metal tube, to which the various different support plates and/or mounts are overcast onto the cylindrical tube from magnesium, or some other lightweight metal, thereby forming a support structure.
A method of manufacturing a support structure is provided. The method includes forming a tubular support member to define a plurality of undulations. The undulations extend longitudinally along a longitudinal axis of the tubular support member, and are angularly spaced about the longitudinal axis. A cast member is then overcast around an outer periphery of the tubular support member such that the cast member is overcast in interlocking engagement with the plurality of undulations in the tubular support member.
A support structure is also provided. The support structure includes a tubular support member. The tubular support member includes a plurality of undulations that extend along a longitudinal axis of the tubular support member. The undulations are angularly spaced about the longitudinal axis. The tubular support member is formed from a metal. A cast member is cast about an outer periphery of the tubular support member in interlocking engagement with the plurality of undulations. The cast member extends transversely away from the longitudinal axis to a distal end. The cast member is overcast onto the tubular support member from a molten metal.
Accordingly, the position of the cast member is rotationally fixed relative to the tubular support member about the longitudinal axis because the cast member is cast around the undulations in interlocking engagement. Furthermore, the undulations increase the rigidity of the tubular support member against localized collapse of the tubular support member during the overcasting process, thereby preventing localized depressions or indentations in the tubular support member and/or the cast member. Additionally, the undulations allow for the tubular support member to flex radially inward as the cast member cools during the overcasting process, thereby preventing hot tearing of the cast member, and reducing fatigue stresses caused by thermal cycling.
The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.
Those having ordinary skill in the art will recognize that terms such as “above,” “below,” “upward,” “downward,” “top,” “bottom,” etc., are used descriptively for the figures, and do not represent limitations on the scope of the invention, as defined by the appended claims.
Referring to the Figures, wherein like numerals indicate like parts throughout the several views, a support structure is generally shown at 20. The support structure 20 may include any size, shape, and/or configuration suitable for multiple different uses. For example and as shown in
Referring to
The support structure 20 and a method of manufacturing the support structure 20 are described herein. The method includes forming the tubular support member 22. The tubular support member 22 is formed to define a plurality of undulations 34, shown in
Referring to
The peaks 38 and the valleys 40 may each define a radius. The radius 42 of the peaks 38 is preferably, but not necessarily, equal to the radius 44 of the valleys 40. Preferably, the radii 42 of the peaks 38 is between the range of three millimeters (3.0 mm) and ten millimeters (10 mm), and the radii 44 of the valleys 40 is between the range of five millimeters (5 mm) and twenty millimeters (20 mm). However, it should be appreciated that the radii 42 of the peaks 38 and the radii 44 of the valleys 40 may differ from the preferred range described above.
The tubular support member 22 may be formed through any suitable process. For example, the tubular support member 22 may be extruded, stamped, bent and/or folded to define the final shape of the tubular support member 22. Preferably, the tubular support member 22 is formed from a metal, including but not limited to steel or aluminum.
The method further includes overcasting the cast member 24 onto the tubular support member 22. The cast member 24 may be overcast onto the tubular support member 22 with any suitable casting process, including but not limited to a die casting process, a sand casting process, a precision sand casting process, a permanent mold casting process, or a lost-foam casting process. The cast member 24 is overcast around an outer periphery 46 of the tubular support member 22 such that the cast member 24 is overcast in interlocking engagement with the undulations 34 in the tubular support member 22. As such, the interlocking engagement between the cast member 24 and the undulations 34 in the tubular support member 22 rotationally fix the cast member 24 relative to the tubular support member 22. Additionally, the undulations 34 increase the strength of the tubular support member 22 to better resist localized depressions and/or indentations in the tubular support member 22 that may occur during the overcasting process.
Overcasting the cast member 24 around the outer periphery 46 of the tubular support member 22 includes positioning the formed tubular support member 22 in a mold. The mold defines a shape of the cast member 24. For example, the mold may define the shape of the cast member 24 to extend outward away from the tubular support member 22 to a cantilevered distal end 48. Due to the interlocking engagement between the undulations 34 and the cast member 24, the cantilevered distal end 48 is restricted from rotation relative to the tubular support member 22. It should be appreciated that the mold may define any suitable and/or desirable shape for the cast member 24, and may further define multiple cast members 24.
Once the tubular support member 22 is positioned within the mold, a molten metal is injected into the mold around the outer periphery 46 of the tubular support member 22. Preferably, the molten metal includes magnesium. However, it should be appreciated that the molten metal may include some other metal, including but not limited to aluminum. After the molten metal is injected into the mold, the molten metal is cooled to form the cast member 24. The molten metal may be cooled in any suitable manner, dependent upon the specific casting process utilized.
The undulations 34 act as an accordion like device to allow radial contraction of the tubular support member 22. As such, the tubular support member 22 is radially compressible inward toward the longitudinal axis 36. During overcasting of the molten metal onto and around the outer periphery 46 of the tubular support member 22, the molten metal heats the tubular support member 22, thereby urging the tubular support member 22 to expand radially outward away from the longitudinal axis 36 and toward the cast member 24. As the molten metal cools, the cast member 24 contracts in opposition to the expansion of the tubular support member 22. However, the geometric configuration of the undulations 34 in the tubular support member 22 allow the tubular support member 22 to flex radially inward about and toward the longitudinal axis 36 while the molten metal cools to form the cast member 24, thereby preventing tearing and/or cracks in the cast metal. Similarly, during use of the support structure 20 in which the support structure 20 is subjected to repeated thermal expansion and contraction cycles, the undulations 34 allow the tubular support member 22 to flex radially inward toward the longitudinal axis 36, thereby preventing damage to the support structure 20 from the repeated expansion and contraction cycles. This is particularly beneficial when the tubular support member 22 and the cast member 24 are formed from different materials having different coefficients of thermal expansion.
While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.
