Patent Application
20240124064
The invention pertains to the manufacture of motor vehicles, and more particularly to structural designs and manufacturing methods suited for making delivery and utility vehicles with an aluminum unibody.
Body-On-Frame (BOF) Design
From the earliest years of the auto industry, cars were designed around a separate body structure attached to a steel ladder frame that held the powertrain and suspension. The detachable body provided seating space and protection for occupants, while the ladder frame handled all the suspension loads, powertrain loads, and supported and distributed the overall vehicle weight and loads.
With the advent of the assembly line process, vehicle bodies were constructed and fully framed, they were then painted, and sometimes pre-assembled with certain interior parts. Then the pre-assembled, painted body would be lowered down onto and attached to the ladder frame, usually with shims sandwiched in between the body and the frame. This refers to the chassis marriage process. The steel ladder frame in turn carried the powertrain, cooling system, drivelines, axles, suspension, steering, brakes, etc. which were all pre-assembled to the frame, referred to as a rolling chassis. The BOF vehicle architecture and assembly approach continues today for pickup trucks and many large SUVs. The major difference from the earliest BOF vehicles is that large elastomeric bushings are sandwiched today between the frame and body to help isolate the occupants from road impacts and vibrations absorbed by the frame. Since the body is only attached with a limited number of elastomeric mounts the body and frame do not act as one in terms of vehicle stiffness. To meet stiffness requirements the frame generally requires additional members and patches adding cost and weight to the vehicle. Overall, BOF allows for increased trailer towing capacity since it can easily distribute trailer tongue weight between front and rear axles. And for off-road use the full frame is better at protecting the vehicle underside and absorbing impacts. Meanwhile for the vehicle manufacturer, a range of wheelbases and vehicle configurations can be accommodated with common BOF platform elements maximizing revenues from their initial capital investment. However, recognizing that the frame rails need a fair amount of section height to generate longitudinal stiffness for the vehicle, and having the body mounted on top of the frame, BOF vehicles inherently feature a higher center of gravity, leaving them more prone to rollovers.
Unibody (Monocoque) Design
The first vehicles to pioneer and introduce this method of construction entered the market at the same time: the '34 Citroen Traction Avant and the '34 Chrysler Airflow. Over succeeding decades, unibody architecture increasingly displaced BOF designs among sedans and light vehicles. A unibody has the main frame rail elements integrated directly into the underbody structure together with various stampings welded together contributing to the overall structure and stampings acting as a shear panels. Unibody vehicles are lighter than BOF designs by at least 200 lbs., they are lower cost, they are more fuel efficient, and overall they offer better handling with better ride quality. In more recent decades, the increased concern over occupant safety accelerated adoption of unibody architecture. Crash impacts are better managed when the forces and loads are reliably dispersed and distributed from the front rails into the side sills, the mid rails and tunnel, and the pillars and roof rails. (With body on frame designs, frontal impact loads can't be directly routed from the frame rails into the body structure since the body and frame are attached through elastomeric body mounts. BOF designs therefore need additional structure and weight to meet today's crash test standards.) A significant drawback of the unibody is the cost and difficulty of repair following a substantial crash event due to the inherent shingling and welded nature of body elements. Unibody creates some concern with vehicle alignment since the underbody is generally build in sub-assemblies often leading to variation. The suspension subframes precisely located to their area on the body may still need adjustment due to body variation. In most cases the front strut mount, critical to wheel alignment is associated with another body sub-assembly, therefore creating another potential point of variation.
For unibody assembly, the sheet metal body in white is typically spot welded, and joined followed by painting of the unibody. After painting, the vehicle assembly can start where all the wiring, suspension, powertrain, cooling system, interior, etc., are fitted. Similar to BOF, the modern unibody has not one, but two suspension sub-frames (front and rear) which are only connected through the unibody. Harsh jolts to the suspension are initially absorbed by the sub-frame prior to dispersion into the unibody. No one element in the unibody could handle such a force directly. Like BOF there are many systems requiring connections when chassis marriage is performed.
“Skateboard” Chassis Concept
This vehicle architecture was originally proposed in the General Motors AUTOnomy concept, a vehicle that would be powered by fuel cells and have many other features that were radically advanced for its time. The innovative “skateboard” style chassis concept housed all the car's working parts in its wheelbase. This meant that the same platform could be used for numerous different models.
Although the AUTOnomy project was never realized, the Skateboard concept and nomenclature nonetheless has stuck and today refers to a powered EV chassis that can have a range of bodies attached to it. The Tesla Model S to a large extent pioneered that approach. A key challenge all the early EV automakers faced was deciding how much range ICE customers would require in their EV, and based on that, where should the batteries be packaged? Tesla's Model S pioneered a shallow battery system that could be neatly packaged under the floor of the vehicle. The flat pack took up the entire volume between both sills and front and rear crossmembers. Other automakers agree and that has now proven to be the optimal approach for battery packaging so it is being adopted en masse. A shallow and flat under floor mounted 1200 to 1300 lb. battery package yields a much lower vehicle center of gravity, enabling superior vehicle handling and stability. Meanwhile the occupant space above the battery pack supports a flat floor with no tunnel structure intruding.
Various companies (Rivian, Canoo, REE, Pininfarina, Byton, Atlis, Rinspeed) have proposed making and selling a flat, shallow battery pack attached to a frame supporting and surrounding the pack, and integrated with front and rear suspension and drive modules. They hope to sell that platform to various automakers who just have to add their “tophat” or body to the “skateboard”. It potentially reduces the capital investment cost for the automaker, while the variable cost leverages volume manufacturing costs when more EV makers adopt someone's skateboard platform.
Current Status
Heavy trucks and semitrailers still rely on the rigid chassis, which typically consists of I-beam or box section elements welded into a ladder arrangement, onto which a planar deck is attached and then any superstructure such as side walls, top, etc. The superstructure plays a limited structural role, for load bearing and for torsional rigidity, with the primary longitudinal rigidity provided by the ladder frame.
Smaller delivery vehicles have begun to incorporate unibody design, but those remain all-steel construction. For lighter-weight delivery vehicles, Grumman aircraft started building aluminum bodied delivery trucks on steel ladder frames after the Second World War. Grumman had acquired extensive expertise working with aluminum, and leveraged that in launching the Grumman Olson truck business making aluminum bodied step vans. That business grew over the years and included producing over 140,000 aluminum bodied LLV (long life vehicle) mail trucks in the 1980s on the Chevrolet S10 steel rolling chassis. But those aluminum-bodied vehicles relied on body-on-frame architecture and not a unibody. To Applicant's knowledge, no one has successfully disclosed or executed an aluminum unibody delivery vehicle, and steel ladder frames continue to provide the load carrying structure with any aluminum body simply attached to the rolling chassis. The rolling chassis Grumman vehicles struggle with outright corrosion of the steel frame and lack galvanic isolation between the aluminum and steel frame where aluminum oxidation is accelerated. In northern climates where salt is used for winter road de-icing, the steel frames have to be completely replaced as often every 8-10 years. The Grumman bodies, in addition, were pop-rivet joined which is difficult if not impossible to automate in a high-volume production process.
Furthermore, delivery vehicles are very different from passenger cars because they commonly lack window and door openings, which in an automobile allow access for the automated assembly machines, spot welders, etc. What is needed, therefore, is a better way to design and build delivery vehicles that allows the use of an all-aluminum unibody that is manufacturable by traditional automated assembly-line methods.
Objects of the present invention include the following: providing a delivery vehicle with improved structural rigidity and reduced weight; providing methods of manufacturing a delivery vehicle having an all-aluminum unibody; providing means for making an aluminum unibody structure formed from prefabricated structural modules and employing both structural adhesives and self-tapping fasteners to join the modules together to form a rigid space frame; providing means for manufacturing a rigid platform and load deck by joining structural extrusions; and providing fixturing means so that complex extruded sub-assemblies may be rapidly assembled using standard joining methods. These and other objects and advantages of the invention will become apparent from consideration of the following specification, read in conjunction with the drawings.
According to one aspect of the invention, a vehicle body comprises a rigid aluminum space frame, the space frame comprising:
The load floor and underbody may optionally comprise aluminum structural castings, forgings, or other components welded or joined to the structural aluminum platform to attach suspension components, battery packs, and other functional modules needed to complete the vehicle. Furthermore, the underbody may function as the enclosure on three sides of the battery pack to be installed from below.
According to another aspect of the invention, a method for making a unitary vehicle body comprises the following steps:
According to another aspect of the invention, a method for manufacturing an aluminum load floor and underbody module comprises:
According to another aspect of the invention, a trailer chassis comprises a rigid aluminum structure, the structure comprising:
According to another aspect of the invention, a trailer body comprises a rigid aluminum structure, the structure comprising:
The drawings accompanying and forming part of this specification are included to depict certain aspects of the invention. A clearer conception of the invention, and of the components and operation of systems provided with the invention, will become more readily apparent by referring to the exemplary, and therefore non-limiting embodiments illustrated in the drawing figures, wherein like numerals (if they occur in more than one view) designate the same elements. The features in the drawings are not necessarily drawn to scale.
The combination of unibody construction and automated assembly has revolutionized the auto industry, not only from a manufacturing aspect but also from a performance aspect. Modern cars are lighter, more agile, safer, and more efficient compared to body-on-frame vehicles. A critical stage in conventional light vehicle construction is joining the various body subassemblies, as shown generally in
The typical assembly approach for holding vehicle body sides, underbody, roof, front of dash, etc., to each other is a framing station. These are large moving “gates” or fixtures carrying the body subassemblies into position. When the gates come together and interlock all subassemblies are temporarily locked in relation to each other. At that point spot welding or rivet setting robots come in to quickly set the geometry so the gates can unclamp and release the body. After the initial critical spot welds are made and the geometry is set, the body advances to other robot stations for more spot welds (known as re-spot stations)
Delivery truck bodies present a unique challenge however. They don't have window and door openings like typical light duty vehicles allowing access to robots or operators with spot weld guns, rivet setting guns, or servo driven self drilling screw guns. Lacking access to these joining flanges, many builders have to assemble the skeleton or space frame first, and then in a second operation attach the exterior skins, as shown generally in
The modular vehicle chassis and body system.
Although Applicants refer in some cases to a “delivery truck” in the generic sense of a boxlike structure including a compartment for the driver, it will be understood that the invention includes vehicles of various sizes and configurations, including such things as mail delivery trucks, small buses, recreational vehicles, cars, all-terrain vehicles (ATVs), utility task vehicles (UTVs), and vans. In some examples, certain aspects of the invention will be shown to offer particular benefits for electric vehicles, but the invention is not limited only to EVs and hybrids, but may also be used for traditional IC engine powered vehicles.
Those skilled in the art of vehicle design will appreciate that the chassis shown and described in the two preceding examples have some characteristics in common with a skateboard architecture, and at the same time, some characteristics of a unibody architecture once the other modules are joined together. The Invention may further be adapted to make the chassis of a unibody automobile, in which case the floor plate made from extrusions would replace the conventional stamped floor pan. The floor plate would preferably be provided with sills on each side edge to engage with corresponding sills on the body side panels.
It will be further appreciated that the Invention lends itself to making the walls and roof self-locating during the assembly process. The Inventive underbody module is one rigid, continuous product after fabrication, so the final machining when complete would be held to machined tolerances as opposed to stamped tolerances. The wall modules would be handled in much the same way. Both the underbody subassembly and wall subassembly would have the critical datum points machined into the modules; therefore, they would be self-locating to each other such as using a self-centering screw fastener in a particular location at the front and having a slot for driving the screw fastener through at the rear of the wall. This aspect greatly simplifies the assembly process known as framing the body. The framing process is then only responsible for keeping the body from being assembled in a “matchboxed” condition in which some of the corners are not square.
All wall and roof modules can be made by creating an extruded aluminum skeletal frame or sections to be sandwiched in a hollow-core composite. The process includes a fiber resin skin layer, hollow-core material, aluminum sections and another resin skin layer to be formed in a heated or microwaved in a mold to cure the composite and form the permanent shape. The process requires skin layers to closely match the thermal expansion of aluminum.
The wall panel known as the front of dash may be made from a stamping or a hollow-core composite. Applicants contemplate that this wall panel and the others can be fully sub-assembled with all components prior to framing and installed as a complete assembly. As shown in
It will be appreciated that the modular aspect of the body allows each module to manufactured and painted individually and, in some cases, the underbody for instance, may not be painted at all. The repair of such body becomes substantially easier due to the production process availability of the complete painted and possibly fully general assembled modules.
It will be further appreciated that the invention provides a great deal of flexibility in the manufacturing process. In the traditional unibody,
Applicants prefer to join the individual extrusions that form the floor or underbody module by continuous full-penetration welds along their abutting edges. The welds are preferably done by laser welding or FSW, magnetic pulse welding, or other suitable structural welding technology, and more preferably by FSW. FSW is a familiar method for joining long seams in aluminum plates to make large planar structures, and this method has been used to make load floors for semitrailers, for example. However, for that application, the aluminum structure doesn't provide the main structural support for the trailer; instead it is just replacing wood planks, which form the traditional load floor in most semitrailers, so consequently the individual extrusions are all of the same cross section making it simple to clamp the extrusions together on a flat tool and form the welds. Conventionally, friction stir welding is done on a planar object in which at least one of the two surfaces is flat, so the assembly can be clamped down and easily held in position. However, Applicants contemplate that the different extrusions will have different profiles in order to achieve the necessary flexural strength, provide mounting points where suspension components will be rigidly attached to the underside of the underbody module, and provide mounting rails for joining the wall modules. So the ideal cross section of the complete platform will not be flat on either surface, making it difficult to establish a flat plane for FSW. Applicants therefore contemplate a welding system and fixture that is custom designed for a particular underbody and has a contour on its upper surface that accommodates whatever protuberances have been formed on the underside of the module.
As shown schematically in
Applicants therefore contemplate using a fixture or cradle, as shown schematically in
The underbody module may further contain structural components attached by welding, mechanical fasteners, structural adhesives, or other familiar means. Such components may be die castings, sand castings, forgings, machined parts, and welded subassemblies. They may serve as mounting points for various other modules such as suspension assemblies, spring mounts and shackles, etc.
Shorter planks may also be arranged to create a space in the middle of the front end of the underbody module to accommodate a forged or cast component welded into place to form the transmission tunnel in the case of an ICE powered vehicle. Those skilled in the art will appreciate that the Inventive assembly process can therefore be viewed as a form of additive manufacturing where the builder will weld in extrusions only of the lengths needed and then attach castings and other elements where they are needed.
Applicants contemplate that the proposed underbody can function as the enclosure on three sides of the battery pack to be installed from below, as shown schematically in
Applicants further contemplate that the channels in the underbody extrusions can potentially be filled with foam material for both insulation and reduction of noise, vibration, and harshness (NVH). One or more of the extrusions may have openings on one surface to allow the interior space within the extrusion to serve as a cable run.
The modular nature of the inventive unibody system allows a manufacturer to customize a truck for particular uses or customers. The following table summarizes some of the options one can choose.
The inventive concept can also be applied to vehicles such as small buses, as shown schematically in
All-terrain vehicles (ATVs) and utility task vehicles (UTVs) often have a floor pan and a tubular space frame, which may be mostly open and serves, in some cases, as a roll cage. Such a structure lends itself well to the Inventive manufacturing process.
Although many examples described herein pertain to the use of aluminum, and more particularly to aluminum extrusions, the invention is not limited only to aluminum alloys nor is it limited only to extrusions. In particular, the basic structural assembly concept may also be achieved using roll-formed steel sections that would be joined to create hollow longitudinal box sections (analogous to the previously described aluminum extrusions) by any suitable joining process, preferably brazing.
Advanced high strength steels up to 1700 MPa, with grade and gauge variation possible in the same set of tooling, are manufactured by Shape Corp., Grand Haven, MI. Roll formed steel components are also manufactured in a variety of sizes and shapes by Advanced Vehicle Assemblies, Rochester Hills, MI, and by voestalpine Roll Forming Corporation, Shelbyville, KY.
Roll formed steel tubes may be joined by any of several brazing processes, such as MIG brazing and plasma brazing.
MIG brazing operates much like MIG welding, but the wire is typically silicon bronze, with a melting temperature of 840° F.; therefore the base metal is not melted. One suitable wire material is ML CuSi3 (MIGAL.CO GmbH, Wattstrasse 2, 94405 Landau/Isar, Germany). When using Si bronze alloys it is recommended that pure argon should be used as the cover gas.
Plasma brazing may employ either pulsed or continuous arc currents. Flat- and vertical-down welding positions are recommended. In opposite to MIG brazing the filler wire is fed into the arc without any current into the focused arc. The deposit of the filler wire is therefore (nearly) independent from the heat input. This makes the seam geometry variable within large boundaries. Plasma brazing with current on the wire is called Plasma hotwire brazing. This variant differs basically only in the additional power provided by another current through the wire. The increased temperature of the filler wire can be used to increase the brazing speed and reduce distortion.
The modular trailer chassis and body system.
The modular design concept of the invention may also be adapted to the construction of small trailers, where several elements of the design make it very easy to configure a trailer to order, even as far as providing options and modifications that may be installed by a local dealer. At the factory, trailer length is selected by the length of the extrusions forming the load platform and underbody, and the width is selected by the number of extrusions laid side-to-side and then welded together. The two outermost extrusions (on the left and right sides of the platform) are preferably constructed as in the previous example of the modular truck, to include structural reinforcements for the attachment of selected side wall modules.
Side wall modules may be factory-built in various heights, with or without solid side panels. Roof modules may also be factory-built, and all modules will preferably have common elements on their mating edges so that a trailer can be configured completely at the factory, or a trailer may be configured at the dealership using factory-supplied modules so that a customer may select a particular configuration or customize a basic configuration in various ways. For example, wall modules may be full height and the skin may be sheet metal, polymer composite, wood composite, or other suitable sheet material. Alternatively, wall modules may be only a foot or more in height and may comprise open frames offering convenient tie down points, or may be covered by a solid skin, expanded mesh, or other surface as needed by the user. The roof module may be covered with an opaque material (sheet metal, polymer composite, wood composite with a polymer outer skin, etc.) or it may be covered with translucent fiberglass or similar material to provide usable natural light inside the trailer.
It will be appreciated that applying the inventive concepts to the design of a trailer chassis creates the equivalent contrast of BOF vs Unibody in vehicles. Traditional trailer manufacturing requires a frame section and a load floor attached to a “body” that typically contributes little to the overall stiffness and rigidity.
Trailers are manufactured in many configurations and weight classes (see https://www.curtmfg.com/trailer-weight for a detailed discussion of trailers and towed campers trailers, the entire contents of which are incorporated herein by reference for background purposes). Data for many trailers are presented in the following table.
It will be appreciated that the modular trailer may further include interior modules to form a camper, or may be outfitted with various fittings on the wall modules in a “camper prep” format so that it is ready for a dealer or user to customize and furnish into a selected camper interior. Trailer floors for the purpose of enclosed trailers, in particular for RV types, can be manufactured and machined creating precise locations for passing plumbing or wiring through the floor where needed and are preferably designed to use standard grommets for sealing these locations. This aspect of the invention eliminates a shortcoming in the current coach building process, which is typically done manually using templates; openings are often hacked out, and not sealed, leaving large openings for insects and vermin to enter.
Furthermore, additional tracks can be designed into the floor for mounting requirements, hidden wire ways with snap lids, and/or tie-down needs. As in the truck chassis, the floor channels can be foam filled for insulation and NVH reduction.
The foregoing process of customization may thus be described as shown in the following table.
There is a growing interest in powered travel trailers that have an on-board battery pack and motors, in order to avoid reducing the range of the tow vehicle [see, e.g., the L1 Travel Trailer, Lightship RV, San Francisco, CA]. The inventive trailer architecture may also be adapted to this application, replacing the ladder chassis used in conventional products. In this case, the space between the two longitudinal structural members again serves as part of a battery enclosure and the interior space of one or both members may serve as a cable run or accommodate coolant piping.
A load floor and underbody would be formed as described earlier using longitudinal extrusions and containing an integral battery enclosure. Two axles incorporating electric drive systems are preferably mounted to the underbody such that a user may adjust the position of one or both axles, thereby increasing or decreasing the wheelbase in order to optimize ride characteristics and maneuverability. Side walls and other body modules would be attached as described earlier to form the complete vehicle.
Applicants contemplate that the drive control system will preferably communicate with that of the tow vehicle, whether the tow vehicle is an EV or is ICE-powered, so that the two vehicles are coordinating their speed, braking, etc. The communication system may be wireless or may comprise a detachable cable physically connecting the tow vehicle and trailer. A separate control system, e.g., a handheld module, may be provided so that a user can independently guide the trailer into a parking space or garage.
Communication with the tow vehicle would typically exploit the tow vehicle's OBD port to obtain wheel speed data, torque demanded data from the ECU based on the accelerator pedal position, etc.; brake pedal position and brake pressure data would be obtained from the ABS controller, and there would be data on the Controller Area Network (CAN bus) on deceleration levels and acceleration levels in terms of g forces from the Electronic Spark Controller (ESC) or vehicle stability controller, and so on. One could monitor messages from the various sensors and modules exchanging info over the tow vehicle CAN bus to gain near real time access through the CAN bus OBD connector port. In turn those CAN signals may be sent through a wireless connection from an OBD CAN connector/relay module to the trailer powertrain controller, telling it how much power and speed to command, either positive for acceleration or negative for braking or deceleration. Those skilled in the art will appreciate that carefully developed firmware will be needed to avoid instabilities that arise from latency and differences in response time. The challenge is to have firmware to work with specific tow vehicles. Each OEM has proprietary CAN messages and these must be available to develop a control program for the powered trailer, allowing for difference in latency, driveline backlash, etc.
Alternatively, the drive control system on the trailer may be configured to have some degree of autonomy to allow the trailer to respond to conditions as they arise. For example, the tongue may be fitted with one or more load cells so that the trailer can apply more or less power to the wheels to minimize tension or compression on the tongue as a way to match trailer and tow vehicle. In the event that the tow vehicle suddenly decelerates, compression on the load cell would signal the trailer drive system to engage regenerative braking, and in extreme conditions to apply brakes as well. Furthermore, the tongue may contain other load cells to detect moments that indicate the tow vehicle is turning, and these signals can cause the trailer drive system to increase the drive level on one side or the other to minimize the lateral load on the tongue and thereby work cooperatively with the tow vehicle to execute turning maneuvers.
Further examples and variations of the invention.
A vehicle body may include a rigid aluminum frame, the frame comprising:
The extrusions may be any suitable aluminum alloy as are familiar in the art. Common aluminum extrusions used in vehicle structures are 6063, 6005, 6105, 6061, 6082, 6110 and some custom alloys with special additions or tighter chemistry specs. The invention could also make limited use of 7003 and 7046 extrusions, with the understanding that they are more expensive to extrude and offer much lower corrosion resistance than 6XXX series grades. So they would preferably be used more in vehicle sides and roof modules where higher yield strength could be exploited without risk of exposure to corrosion.
Each module or subassembly may be formed by placing individual extruded components into a locating fixture and securing the joints using any conventional means, including rivets, screws, structural adhesives, welding, brazing, etc., alone or in combination. Suitable welding processes may include spot welding, MIG welding, ultrasonic welding, or magnetic pulse welding. Subassemblies may further include sheet metal components such as corner gussets, and holes, hardware, or other features particular to the selected configuration and joining methods
The wall and roof modules may further comprise a skin, which may be sheet metal, polymer composite, wood composite faced with an exterior polymer or sheet metal layer, or other suitable sheet-like material. The roof module may have a skin of translucent fiberglass composite to admit natural light into the interior.
The load floor/underbody module may be formed from a series of extrusions, each having a rectangular cross section, and oriented longitudinally, i.e., running from the front to the rear of the vehicle. The extrusions may preferably have different profiles depending on their location. The extrusions may be joined by friction stir welding, laser welding, brazing, or other suitable means. The underbody module may further have hardware rigidly attached to the underside for various purposes, such as the attachment of suspension components. Such hardware may include aluminum castings, forgings, machined subassemblies, or other structural members.
The underbody module may further include a box structure defining a battery compartment if the body is intended for an electric or hybrid electric vehicle.
Joining of individual modules or subassemblies to one another may include fasteners, such as rivets or self-tapping or thread forming/thread rolling screws, and structural adhesives. When structural adhesives are used, means may be provided to maintain a uniformly thick bond layer in order to optimize the bond strength.
After assembly, the structure may be given a surface treatment such as painting or powder coating. The structural adhesive and powder coating may be selected such that the bake temperature for the powder coat is the same as the cure temperature of the structural adhesive, so that both process steps may be carried out simultaneously in one bake operation. Notablyly, the modules could be prepainted or coated, because the inventive assembly process is based on adhesives and fasteners to join the modules instead of MIG welding or spot welding, high temperature processes that would damage a prepainted component. This unique feature would allow for greatly reduced paint shop capital investment and almost zero paint shop VOC emissions while enabling use of superior durability powder paint coatings.
According to another aspect of the invention, a method for making a unitary truck body comprises the following steps:
The step of forming the load floor and underbody module may include friction stir welding adjacent extrusions to one another while supporting the extrusions in a fixture that compensates for their different cross sections to align the weld seams in a common plane.
The step of making wall and roof modules may include cutting extrusions to length and securing them in a fixture to set the frame dimensions, then joining the extrusions to one another with one or more of: fasteners, structural adhesives, and weld joints. It may further include the step of attaching a skin comprising sheet metal, wood composite, polymer composite, fiberglass, or other suitable sheet-like materials. The skin may include a precipitation hardening aluminum alloy, which may be installed in an untreated condition and then precipitation hardened during the curing of the structural adhesive. The skin may further be given a coating of paint, dry powder coat, etc. A dry powder coat may be formulated so that its bake temperature coincides with the cure temperature of the structural adhesive so that the two processes may be carried out in a single oven treatment.
The step of joining the different structural modules to one another may include the use of self-tapping or thread forming/thread rolling fasteners and thermosetting structural adhesive.
According to another aspect of the invention, a method for manufacturing an aluminum load floor and underbody module comprises:
The different cross sections of extrusions may include at least one extrusion that has a significantly deeper profile than others and thereby provides improved bending strength in the longitudinal direction. The extrusions running along the edges of the module may have cross sections containing structural reinforcements to engage mechanical fasteners for joining the wall modules. One or more extrusions may include ridges that may be partially removed after welding to provide tabs for attachment points or other purposes.
According to another aspect of the invention, a trailer chassis comprises a rigid aluminum structure, the structure comprising:
The different cross sections of extrusions may include at least one extrusion that has a significantly deeper profile than others and thereby provides improved bending strength in the longitudinal direction. The extrusions running along the edges of the load floor may have cross sections containing structural reinforcements to engage mechanical fasteners for joining wall modules. One or more extrusions may include ridges that may be partially removed after welding to provide tabs for attachment points or other purposes.
According to another aspect of the invention, a trailer body comprises a rigid aluminum structure, the structure comprising:
According to other aspects of the invention, a major advantage to the longitudinal FSW section platform is the many shapes and sizes that can be run on the same process equipment:
According to another aspect of the invention, when joining a body by means of adhesive and fasteners such as trilobular screws this step can be done either by robot or manually. An operator using a DC nutrunner can determine the number of screws run to a given torque curve which proves the number of screws required have been run to proper torque, thereby aiding in overall quality assurance processes. The process is low-cost in terms of capital expenditure, highly flexible, and adaptable to volume requirements. As volume increases the more difficult to reach fastened locations can be done by operators while the easiest locations can be completed with robots.
According to another aspect of the invention, a repair tool for cutting the adhesive in case of module replace is contemplated. The repair tool is preferably a battery-operated heated blade design with interchangeable blades of varying shape to separate all adhesive joint configurations. Referring to
This application claims the benefit of U.S. Prov. Pat. Appl. No. 63/416,570, entitled, “Unitary Truck Body and Associated Manufacturing Methods” and filed by Applicants on Oct. 16, 2022, the entire disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63416570 | Oct 2022 | US |
