Patent Application
20060277960
The present invention relates to a roll-forming apparatus with a sweep station adapted to impart multiple sweeps (i.e., non-uniform longitudinal curvatures) into a roll-formed beam.
Roll-formed bumper beams have recently gained wide acceptance in vehicle bumper systems due to their low cost and high dimensional accuracy and repeatability. Their popularity has increased due to the ability to sweep (i.e., provide longitudinal curves) in the roll-formed beam sections in order to provide a more aerodynamic appearance. For example, one method for roll-forming a constant longitudinally curved beam is disclosed in Sturrus U.S. Pat. No. 5,092,512.
The aerodynamic appearance of vehicle bumpers is often further enhanced by forming a section of the front surface at ends of the bumpers rearwardly at an increased rate from a center of the bumper beam. This is typically done by secondary operations on the bumper beam. Exemplary prior art secondary operations for doing this are shown in Sturrus U.S. Pat. No. 5,092,512 (which discloses deforming/crushing ends of tubular beam), and are also shown in Sturrus U.S. Pat. No. 6,240,820 (which discloses slicing ends of a beam and attaching brackets), Heatherington U.S. Pat. No. 6,318,775 (which discloses end-attached molded components), McKeon U.S. Pat. No. 6,349,521 (which discloses a re-formed tubular beam), and Weykamp U.S. Pat. No. 6,695,368 and Reiffer U.S. Pat. No. 6,042,163 (which disclose end-attached metal brackets). However, secondary operations add cost, increase dimensional variability, and increase in-process inventory, and also present quality issues. It is desirable to eliminate the secondary operations required to form the bumper ends with increased rearward sweep. At the same time, vehicle manufacturers want to both maintain low cost and provide flexibility in bumper beam designs. Thus, there are conflicting requirements, leaving room for and a need for the present improvement.
It is known to provide computer controls for bending and roll-forming devices. See Berne U.S. Pat. No. 4,796,399, Kitsukawa U.S. Pat. No. 4,624,121, and Foster U.S. Pat. No. 3,906,765. It is also known to make bumper beams with multiple radii formed therein. For example, see Levy U.S. Pat. No. 6,386,011 and Japan patent document JP 61-17576. Still further, it is known to bend tubing and beams around the arcuate outer surface of a disk-shaped mandrel by engaging the tube to wrap the tube partially around the mandrel until a desired permanent deformation occurs. For example, see Miller U.S. Pat. No. 1,533,443 and Sutton U.S. Pat. No. 5,187,963. Nonetheless, it is important to understand that bumper beams for modern vehicles present a substantial increase in difficulty due to their relatively large cross-sectional size and non-circular cross-sectional shape, the high strength of materials used herein, the very tight dimensional and tolerance requirements of vehicle manufacturers, the cost competitiveness of the vehicle manufacturing industry, and the high speed at which modern roll-forming lines run.
Notably, existing sweep mechanisms on roll-forming equipment are often made to be adjustable. For example, Sturrus '512 discloses a manually adjustable sweep station. (See as Sturrus '512, FIGS. 10-11, and column 6, lines 1-9.) However, even though the sweep station is adjustable, it does not necessarily mean that the apparatus is able to manufacture beams having multiple sweep radii therein. For example, since the sweep station in the apparatus of Sturrus '512 is manually adjustable, as a practical matter it cannot be adjusted quickly enough to allow formation of regularly-spaced different curves in a single vehicle bumper beam section. Notably, bumper beams are usually only about 4 to 5 feet long and roll-forming line speeds can reach 4000 to 5000 feet per hour, such that any change in sweep must be accomplished relatively quickly and very repeatably. Certainly, non-uniform longitudinal curvatures cannot be uniformly repeated formed along a length of a continuous beam by manual means and further cannot productively and efficiently be made in high speed rollforming operations using slow-acting automated equipment. Accordingly, there remains a need for a method and roll-forming apparatus capable of manufacturing a roll-formed beam with different radii along its length “on the fly” (in other words simultaneously as part of the roll-forming process), where the method and apparatus do not require substantial secondary operations (or at least they require less secondary processing), such as cutting, fixturing, welding, secondary forming and/or post-roll-forming attachment of bracketry.
Renzzulla U.S. Pat. No. 6,820,451 is of interest for disclosing a power-adjusted sweep station. As best understood, Renzzulla '451 discloses an adjustable sweep station for a roll-forming apparatus where an upstream roller (16) is followed by an adjustable carriage adjustment assembly (14) that incorporates a primary bending roller (18) and an adjustable pressure roller (20) forming a first part of the sweep mechanism (for coarse adjustment of sweep), and also an auxiliary roller (22) forming a second part (for fine adjustment of sweep) (see Renzzulla '451, column 14, lines 20-22.). In Renzzulla '451, the lower primary roller (18) (i.e., the roller on the downstream/convex side of the swept beam) is preferably positioned above the line level of the beam being roll-formed (see FIG. 1, “flexing roller 18 is vertically higher than the line level”, see column 10, line 65 to column 11 line 1.) The second roller (20) (i.e., the roller on the concave side of the swept beam) is supported for adjustable arcuate movement around the axis (shaft 90) of the first roller (see FIGS. 15-16) to various adjusted positions for putting pressure on the continuous roll-formed beam. Actual flexure of the beam occurs upstream of the rollers (18/20) at location 143. (See column 12, line 45-46.) A control assembly (130) is adapted to move the roller (20) along its arcuate path of adjustment. (See column 8, line 62+, and see FIGS. 1-2). An auxiliary carriage assembly (110) is positioned to adjust roller (22) on the primary carriage assembly (14) and is adjustable by operation of an adjustment assembly (137). The patent indicates that both adjustments can be done “on the fly” (see column 14, line 4), and that the primary and auxiliary assemblies can be adjusted for coarse and fine sweep adjustments, respectively. (See column 14, line 22).
Although the device disclosed in the Renzzulla '451 patent can apparently be power-adjusted while the roll-forming apparatus is running, the present inventors find no teaching or suggestion in Renzzulla '451 for providing a controlled/timed adjustment function nor coordinated control function for repeatedly adjusting the device to provide a repeated series of dissimilar sweeps (i.e., different radii) at selected relative locations within and along the length of a single bumper beam segment (e.g., within a span of about 4 to 5 feet as measured along a length of the roll-formed continuous beam). Further, there is no teaching in Renzzulla '451 to form a multi-swept beam using a computer controlled sweep apparatus in continuation with a coordinated computer-controlled cut-off device adapted to cut off individual bumper beam sections from the continuous beam at specific locations related to particular sweep regions. Further, based on the density of threads suggested by the FIGS. 1-2 (and also based on the lack of any discussion in Renzzulla '451 regarding automated “cyclical” adjustment), it appears that the device of Renzzulla '451 suffers from the same problem as manually adjustable sweep stations—i.e., that it cannot be adjusted fast enough to cause multiple sweeps within a 4 to 5 foot span along the continuous roll-formed beam, given normal relatively fast linear speeds of roll-forming mills.
There is potentially another more fundamental problem in sweep station of the Renzzulla '451 patent when providing tight sweeps (i.e., sweeps with short radii) along a continuous beam. The Renzzulla '451 patent focuses on a sweep station where a first relatively stationary (primary) forming roller (18) is positioned above a line level of the continuous beam (see column 10, line 65 to column 11 line 1) to deflect a continuous beam out of its line level, and discloses a second movable/adjustable pressure roller (20) that is adjustable along an arcuate path around the axis of the first relatively-stationary (primary) roller (18) in order to place bending forces at a location (143) forward of (upstream of) the primary roller (18) . . . the upstream location (143) being generally between and upstream of the primary roller (18) and the upstream support roller (16). (See FIG. 16, and column 12, lines 45-46). As the Renzzulla sweep mechanism is adjusted to form tighter and tighter sweeps (i.e., sweeps with increasingly smaller radii), the location (143) of bending potentially moves even farther upstream and away from the primary roller (18). By forcing flexure and deformation of the beam to occur at an unsupported upstream location (143), the beam walls effectively are allowed to bend in an uncontrolled fashion. This makes it very it difficult to control twisting and snaking, difficult to control undesired warping and wandering, and also difficult to control dimensional variations. These variables combine and lead to unpredictability of deformation in the beam and the beam walls. In other words, as the unsupported distance increases (i.e., as tighter sweeps are formed), the problem of uncontrolled movement and deflection of the beam walls becomes worse . . . potentially leading to dimensional and quality problems. Compounding this problem is the fact that the diameter of rollers 16 force the rollers 16 to be positioned away from the rollers 18 and 20 . . . which results in the contact points of the rollers 16 and 18 against the beam to be a relatively large distance equaling basically the distance between the axles on which the rollers 18 and 20 rotate. This large unsupported distance allows the walls of the roll-formed beam to wander and bend uncontrollably as deformation occurs in this area of no support.
Thus, a system having the aforementioned advantages and solving the aforementioned problems is desired.
In one aspect of the present invention, an apparatus includes a roll-forming apparatus adapted to roll-form a sheet of material into a continuous beam having a longitudinal line level, the continuous beam having a first surface and an opposing second surface. The apparatus further includes a sweep station in-line with the line level and adapted to form a longitudinal shape into the continuous beam. The sweep station includes a primary bending roller tangentially engaging the continuous beam along the line level and an armature for holding the continuous beam tightly against the primary bending roller for a distance partially around a downstream side of the primary bending roller to form a sweep. The sweep station further includes actuators for adjustably moving the armature at least partially around the downstream side of the primary bending roller between at least first and second positions for imparting at least first and second different longitudinal shapes, respectively, into the continuous beam.
In another aspect of the present invention, an apparatus includes a roll-forming apparatus adapted to roll-form a sheet of material into a continuous beam having a line level, the continuous beam having a first surface and an opposing second surface. A sweep station is positioned in-line with and downstream of the roll-forming apparatus and adapted to form a longitudinal shape into the continuous beam. The sweep station includes a first roller and a second roller opposite the first roller that opposes the first roller to pinch the continuous beam therebetween and also includes a mechanism for controllably adjusting a position of the second roller. The first roller is positioned to tangentially engage the first surface of the continuous beam and is maintained in a relatively stationary position when roll-forming the continuous beam. The second roller is also positioned to tangentially engage the second surface of the continuous beam. The first roller defines a first axis of rotation and the second roller is movable by the mechanism along an arcuate path around an adjustment axis that is on a same side of the continuous beam as the first axis and that is located at or upstream of the first axis so that, upon adjustment, the second roller moves toward a position that is more downstream relative to the first roller.
In another aspect of the present invention, an apparatus includes a sweep apparatus including axles for supporting rollers that are adapted to form a sweep into a continuous beam. An armature is operably mounted on a stationary one of the axles, the armature supporting at least a particular one of the rollers for imparting a sweep into the continuous beam. An automated adjustment device is provided for repeatedly arcuately adjusting an angular position of the armature to create a repeating pattern of longitudinal shapes in the continuous beam, including automatically moving the particular one roller toward different downstream positions relative to the other roller to change the sweep being imparted into the continuous beam.
In yet another aspect of the present invention, an apparatus includes a sweep apparatus having a primary bending roller tangentially engaging the continuous beam. An opposing holding roller is adjustable to different positions downstream of the primary bending roller and holds the continuous beam against the primary bending roller to cause a desired sweep to be imparted into the continuous beam. At least one stabilizing roller tangentially engages the continuous beam upstream of the primary bending roller. First, second, and third drive motors drive the primary bending roller, the holding roller and the stabilizing roller, respectively. A controller independently controls a drive speed of each of the first, second, and third rollers to control and manage stress on the continuous beam while in the sweep station in order to form a more consistent swept shape of the continuous beam.
In still another aspect of the present invention, a method includes steps of providing a sheet of high strength material having a tensile strength of at least 80 KSI; providing a roll-forming apparatus capable of forming the sheet at speeds of at least about 900 feet per hour, the roll-forming apparatus including an adjustable sweep station, an actuator, and a controller operably connected thereto for automatically rapidly adjusting the sweep station to generate different sweep radii; and roll-forming the sheet to form a continuous beam having a continuous cross section and, simultaneous with and near an end of the roll-forming, sequentially and repeatedly imparting different sweeps while running the roll-forming at a line speed of at least about 900 feet per hour.
The present apparatus focuses on a sweep station where a roll-formed continuous beam is received and tangentially engages a first forming roller, and draws or “wraps” the continuous beam partially around the stationary roller, doing so by moving the gripping point circumferentially around a downstream side of the primary roller until the continuous beam takes on enough permanent deformation to retain the desired amount of sweep. The present apparatus focuses on gripping the beam at a tangential position at the primary roller, with the primary roller being tangentially in-line with the line level of the continuous beam. The present apparatus then provides structure for wrapping the continuous beam partially around the stationary roller downstream of the primary roller as the continuous beam continues to tangentially/circumferentially engage the primary roller, with the pinch point moving circumferentially around the stationary roller toward a downstream side of the primary roller during any adjustment of the sweep function on the continuous beam.
These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.
The present roll-former mill apparatus 19 (
The illustrated roll-formed segmented beam 21′ (
The illustrated roll-forming apparatus is capable of line speeds that can reach 5000 feet per hour (or more), and is adapted to make tubular or open beam sections having cross-sectional dimensions of, for example, up to 4×6 inches (more or less). The illustrated sweep station 20 (
The sweep station 20 (
The top bearing 29 is manually vertically adjustable by a threaded support mechanism 29A in order to manually change a distance between the axles 27 and 28 (i.e., to change a “pinch” pressure of the rollers). Similar manual adjustment designs are known in the prior art, and are used on roll-forming machines to accommodate different sized roll dies for making different size beam cross sections. Notably, adjustment is typically done manually as part of setting up the roll-forming apparatus and during initial running of the roll-forming apparatus, and is typically not done as part of operating the roll-forming apparatus in production to form beams with constantly changing sweeps and repeated sweep profiles.
A significant part of the present invention is the automatic “cyclical” adjustability and quick/accurate adjustability of the “second half” assembly 30A (
The location and timing of the angular movement of the armature (i.e., subframe 35 and roller 61) and also the timing of the cut-off device 22 is controlled by a controller 56 which controls the actuation system via circuit 55 (
Especially when a relatively sharp sweep (i.e., small radius sweep) is being formed, maximum control over the walls of the continuous beam 21 is required. This is particularly true when ultra high strength materials are used and/or when different sweeps are being imparted into the continuous beam 21, since these tend to result in greater dimensional variation in the walls. Notably, the axles 31/32 are preferably positioned as close as practical to the axles 27, 28 so that the distance between the rollers is minimized. Of course, the size of the rollers 60, 61, and 62, 63 affects how close the axles 27, 28 and 31, 32 can be positioned. It is noted that angular adjustment of the subframe 35 along path P1 (
It is also important to note that the amount of “wandering”, twisting, snaking, and uncontrolled back-and-forth bending of different walls on the continuous beam 21 can be minimized by maximizing tensile stresses during sweep-forming bending and minimizing compressive forces during sweep-forming bending. We, the present inventors, have discovered that independent drives on each of the axles for independently driving the rollers 60-63 can have a very advantageous effect. By driving each roller 60-63 at optimal speeds, stresses along the various walls of the continuous beam 21 can be optimally controlled. Notably, one reason that it is important to independently control individual roller rotation speeds is because it is not always easy to calculate exactly what speed individual rollers should be driven at. For example, a top roller (62) may contact the beam 21 along a top wall as well as along a bottom wall, such that one of the contact points must necessarily slip a small amount. Secondly, as a sweep is imparted into the continuous beam 21, the speed of rotation of rollers 62 and 63 will change, depending on the sweep. Still further, different cross-sectional shapes will undergo complex bending forces during the sweeping process, such that some on-the-floor adjustment of axle speeds will be necessary while operating the roll mill to determine optimal settings. It is important that compressive stresses be minimized, because compressive stresses (and not tensile stresses) have a greater tendency to cause the walls of the beam to form undulations and wave-like shapes that are difficult to predict or control. Accordingly, the independent drive motors allow the rollers to be rotated at individualized (different) speeds that “pull” top and bottom regions of the beam 21 through the sweep station, yet without causing any of the rollers to slip or spin or to “fight” each other. The drives for the different axles are independently controlled by the computer controller that is also operably connected to the roll mill, such that overall coordinated control of the machine is possible, including all aspects of the sweeping station.
In the illustrated arrangement of
The illustrated support is provided in the form of a sliding “bridge” support 70 (
Also, it is contemplated that support can be provided inside the tubular beam by an internal mandrel stabilized by an upstream anchor (see
A pair of actuators 50 (
By this arrangement, the degree of sweep (curvature) can be varied in a controlled cyclical/repeated manner as the beam 21′ is being made. For example, this allows the beams 21′ to be given a greater sweep at their ends and a lesser sweep in their center sections immediately “on the fly” while roll-forming the beams. Due to the fast-acting nature of the actuators 50 and the efficient and controlled nature of the sweep station including positioning of the rollers 62, 63, the changing sweeps can be effected quickly and accurately, even with line speeds of 2500 to 5000 feet per hour. Notably, the movement of the roller 63 around the axis of roller 62 imparts a natural wrapping action to the beam 21 as the beam 21 is “drawn” around the roller 62 . . . such that the sweeps formed thereby are well-controlled and the mechanism is durable and robust.
The adjustable bottom roller 63 effectively holds the continuous beam 21 tightly against a downstream side of the circumferential surface of the top roller 62 when the bottom roller 63 is rotated around the axis of the top roller 62. For this reason, the top roller 62 is sometimes called the “forming roller” and the adjustable bottom roller 63 is sometimes called the “pressing roller” or “retaining roller.” It is contemplated that the adjustable bottom roller 63 could potentially be replaced (or supplemented) by a separate holding device designed to grip and hold the continuous beam 21 against (or close to) the circumference of the top roller 62 as the continuous beam 21 wraps itself partially around the top roller 63. For example, the separate holding device could be an extendable pin or rod-like arm that extends under the beam 21 and is carried by rotation of the roller 62 partially around the axle to the roller 62, thus forming a short radius sweep. The “tight” sweep would be long enough such that, when the beam sections 21′ are cut from the continuous beam 21, half of the short radius sweep forms a last section of a (future) beam section 21′ and also the other half forms the first section of a (subsequent future) beam section 21.
It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.
