BRIEF DESCRIPTION OF THE DRAWINGS
The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein:
FIG. 1 is a representative side elevational view of a prior art hydroformed automotive frame component formed from a tubular blank;
FIG. 2 is an end view of the prior art hydroformed component depicted in FIG. 1;
FIG. 3 is a side elevational view of a hydroformed automotive frame component formed from a tubular blank manufactured through a roll-forming process in accordance with the principles of the instant invention to establish a double cell frame component with an integral internal reinforcement separating the two cells;
FIG. 4 is an end view of the hydroformed frame component depicted in FIG. 3;
FIG. 5 is a diagrammatic end view of a first embodiment of the roll-formed tubular blank used to create the hydroformed frame component depicted in FIGS. 3 and 4;
FIG. 5A is a diagrammatic end view of a second embodiment of the roll-formed tubular blank used to create the hydroformed frame component depicted in FIGS. 3 and 4;
FIG. 6 is a cross-sectional view of a tubular blank formed by welding together tubular members, an optional third tubular member being shown in phantom;
FIG. 7 is a diagrammatic end view of the tubular blank depicted in FIG. 5 placed into a hydroforming die to start the hydroforming process;
FIG. 8 is a diagrammatic end view of the deformation undertaken by the tubular blank during the hydroforming process;
FIG. 9 is a diagrammatic end view of the finished hydroformed component formed with dual cells and an internal reinforcement rib between the two cells;
FIG. 10 is a diagrammatic end view of the tubular blank depicted in FIG. 6 placed into a hydroforming die to start the hydroforming process;
FIG. 11 is a diagrammatic end view of the deformation undertaken by the tubular blank during the hydroforming process with differential pressure placed in the two cells of the tubular blank; and
FIG. 12 is a diagrammatic end view of the finished hydroformed component formed with dual cells and a displaced internal reinforcement rib between the two cells.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1-2, a known representative frame component used in the manufacture of an automobile can be seen. The final hydroformed component 10 is formed through the known hydroforming process into a shaped member having a predetermined shape and size, as reflected in the cross-sectional view of FIG. 2. The automobile into which this frame member 10 is utilized has a frame design that requires a component with this particular shape, size and configuration. This prior art frame component 10 has certain structural properties defining the strength, rigidity and stiffness for the component 10. To increase the strength or other properties of this particular component 10, external reinforcements (not shown) or additional parts (not shown) would be added strategically to the component 10 as needed. Such additional parts or reinforcements add manufacturing steps, and additional materials to attain the requisite structural properties, and thus, increase the cost of manufacturing the component and the automotive vehicle into which this component 10 is assembled.
Referring to FIGS. 3 and 4, a dual cell hydroformed automotive frame component 20 incorporating the principles of the instant invention can be seen. The dual cell component 20 has the same exterior predetermined size, shape and configuration as the previously known component 10, depicted in FIGS. 1 and 2, but is formed with a first cell 21, a separate second cell 22 and a reinforcement rib 25 dividing the two cells 21, 22. This dual cell component 20, due to the internal reinforcement rib 25, has greater strength, rigidity and stiffness as compared to the conventional hydroformed member 10 shown in FIGS. 1 and 2, yet has the same external appearance and can be easily substituted into the automotive design. The dual cell member 20 is manufactured through a hydroforming process that will be described in greater detail below.
The instant invention combines two distinct manufacturing processes to create the dual cell hydroformed component 20. The tubular blank 30 is formed in multiple cells prior to be subjected to the hydroforming process. The tubular blank can be created through a roll-forming process that creates a dual cell tubular blank 30, as can be seen best in FIGS. 5 and 5A. In FIG. 5, the roll-forming process starts with a flat piece of sheet metal parent material (not shown) and instead of rolling the sheet metal into a simple hollow tube, forms a dual cell blank 30. The sheet metal parent material that is formed into the blank 30 begins with a first end 31 and an opposing second end 32. From the first end 31, the parent material is rolled into a circular configuration that forms the upper cell 36 from a portion of the sheet metal. The roll-forming process continues to form the lower cell 37 in a generally circular configuration terminating with the second end 32 mating against the side of the upper cell 36 where the second end 32 is welded to the outside of the second cell 36. The first end 31 is then welded to the outside of the lower cell 37 at a position that is spaced from the second end 32 with an intermediate strip 35 of the parent material extending between the first and second ends 31, 32. Since the dual cell blank 30 is formed from a continuous piece of sheet metal parent material extending from the first end 31 to the second end 32, the strip 35 is an integral part of the blank 30. Furthermore, the strip 35 forms the barrier between the upper and lower cells 36, 37.
An alternative configuration for the dual cell tubular blank 30 can be seen in FIG. 5A. The first end 31 is rolled into generally circular upper cell 36 and then into the generally circular lower cell 37. The first end 31 is welded to a point on the sheet metal to define the first cell 36, while the second end 32 is welded along the upper cell 36 at a distance spaced from the first end 31 such that the strip of sheet metal becoming the barrier 35 between the upper and lower cells 36, 37 extends from the first end 31, rather than along an intermediate strip of the sheet metal per the configuration of FIG. 5. Either configuration of the dual cell blank 30 works satisfactorily in the hydroforming process; however, certain characteristics of one configuration may be desired over the other, as can be recognized below.
Alternate, more conventional, manufacturing methods can be used to create the tubular blank 40. For example, as seen in FIG. 6, two tubular members 41, 43, particularly square tubing, can be welded together with the two co-joined sides 42, 44 of the respective tubes 41, 43 forming the internal rib 45 of the tubular blank 40. The two tubes 41, 43 do not have to be the same size, or even be rectangular, so long as two adjacent sides 42, 44 can be welded together to form a multiple cell tubular blank 40. This concept of welding tubes together can be expanded to create a tubular blank 40 with more than two cells by welding a third tube 46, shown in phantom in FIG. 6, or yet additional tubes (not shown) to the second tube 44.
The hydroforming process is substantially the same as the conventional process, except that special end caps (not shown) are required to permit the introduction of fluid under pressure into each of the cells 36, 37 of the dual cell blank 30 independently. The high pressure fluid in each of the cells 36, 37 acts to push the sheet metal defining each respective cell 36, 37 outwardly onto the surface of the die 15 so that the end result of the process is the desired exterior shape of the hydroformed component.
As can be seen in FIGS. 7-9, the dual cell tubular blank 30 is placed into the die 15 and fluid injected independently into each of the upper and lower cells 36, 37. The deformation induced by the high pressure fluid is reflected in FIG. 8. The barrier 35 can stretch with the expansion of the upper and lower cells 36, 37 to form the final hydroformed component 20 that has an upper cell 21, a lower cell 22 with an integral internal reinforcement rib 25 positioned between the two cells 21, 22, formed from the stretched barrier 35. The internal reinforcement rib 25 substantially adds to the strength of the component 20, as compared to the conventionally formed component 10, without adding significantly to the cost of producing the hydroformed component 20. Essentially the only extra costs associated with the production of such a dual cell hydroformed component 20 is the slightly additional length of sheet metal required to form the barrier 35 and the extra weld needed to weld the first and second ends 31, 32 to the sides of the cells 36, 37, as opposed to a single weld to each other to form a conventional single cell tubular blank.
One skilled in the art will recognize that a differential in the pressure exerted on the fluids in the respective cells 36, 37 during the hydroforming process can provide a surprising result. As can be seen in FIGS. 10-12, the dual cell tubular blank 30 can be placed into a forming die 15 and fluid injected under high pressure into each of the cells 36, 37 independently. By increasing the pressure of the upper cell 36 relative to the lower cell 37, the position of the barrier 35 forming the reinforcement rib 25 can be displaced or twisted within the die. As is reflected in FIG. 11, the deformation of the upper and lower cells 36, 37 due to the high pressure fluid injected therein expands the sheet metal cells 36, 37 outwardly against the surface of the forming die 15. However, a higher differential pressure in the upper cell 36 can push the unsupported first end 31 of the blank 30 into the lower cell 37 to cause a deflection or a twisting of the barrier 35. The final result is depicted in FIG. 12 with the integral internal reinforcement rib being oriented in a diagonally extending position to provide different strength and stiffness characteristics than the configuration depicted in FIG. 9.
It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention.
Patent Application
20080028614
