Patent Application
20190062129
Example embodiments relate to a lightweight crane.
Conventional cranes are designed to carry relatively heavy loads. As a consequence, conventional cranes are designed using steel due to steel's high strength and stiffness. Steel, however, is a relatively heavy metal adding significant weight to the crane. Other materials, for example, aluminum, while light in weight, have traditionally been ignored as a material suitable for crane designs due to its relatively low strength and high flexibility.
Example embodiments relate to a lightweight crane. In one nonlimiting embodiment the crane is comprised of a telescoping boom having a first boom nested in a second boom which, in turn, is nested in a third boom. The first, second, and third booms may be made from aluminum to reduce the weight of the crane. The first boom may have a first section and a second section. The first section may be an open section and may be configured to accommodate a structural member to which an actuator may be attached. The second section may be a closed section configured to carry shear loads. The first and second booms may have inclined lower surfaces so that the first boom self-aligns with the second boom and the second boom self-aligns with the third boom.
The disclosure will be better understood and when consideration is given to the drawings and the detailed description which follows. Such description makes reference to the annexed drawings wherein:
Example embodiments will now be described more fully with reference to the accompanying drawings, in which example embodiments of the invention are shown. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the sizes of components may be exaggerated for clarity.
It will be understood that when an element or layer is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it can be directly on, connected to, or coupled to the other element or layer or intervening elements or layers that may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, and/or section from another elements, component, region, layer, and/or section. Thus, a first element component region, layer or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of example embodiments.
Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the structure in use or operation in addition to the orientation depicted in the figures. For example, if the structure in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The structure may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Embodiments described herein will refer to plan views and/or cross-sectional views by way of ideal schematic views. Accordingly, the views may be modified depending on manufacturing technologies and/or tolerances. Therefore, example embodiments are not limited to those shown in the views, but include modifications in configurations formed on the basis of manufacturing process. Therefore, regions exemplified in the figures have schematic properties and shapes of regions shown in the figures exemplify specific shapes or regions of elements, and do not limit example embodiments.
The subject matter of example embodiments, as disclosed herein, is described with specificity to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. Rather, the inventors have contemplated that the claimed subject matter might also be embodied in other ways, to include different features or combinations of features similar to the ones described in this document, in conjunction with other technologies. Generally, example embodiments relate to a light-weight crane.
In example embodiments, the crane 1000, as described above, may include the second actuator 5000. The second actuator 5000 may be at least partially enclosed by the first, second, and third booms 2100, 2200, and 2300. For example, as shown in
In example embodiments the first boom 2100 may slide along the second boom 2200 in a telescoping manner. This is possible due to the open section 2110 of the first boom 2000. That is, the structure 2250 and rod of the second actuator 5000 may be accommodated within the open section 2110 as the first boom 2100 moves within the second boom 2200. In example embodiments the first boom 2100 may be connected to the second boom 2200 via a pin. For example, the first boom 2100 may include a first aperture 2102 near a first end thereof and a second aperture 2104 near a second end thereof (see
In the conventional art, telescoping boom members of a crane are generally made of steel or some other relatively heavy metal. However, the crane 10000 of example embodiments may be made from material typically not suitable for cranes. For example, in one nonlimiting example embodiment, the booms 2100, 2200, and 2300 are made from aluminum. This is only possible in consideration of the various inventive design features cited herein. Furthermore, the example booms 2100, 2200, and 2300 may be made from an extrusion process which allows great flexibility in the design of the sections. For example, if necessary, certain elements may be thickened to reduce stress and/or increase stiffness of an element.
In example embodiments the walls of the booms 2100, 2200, and 2300 may have varying thickness. Small strips of thicker wall can be added to the inside of boom 2200 to add stability to boom 2100. Since the primary bending load on the booms may be in one direction, more material may be placed at the top and bottom of the sections to maximize resistance to bending in the direction needed.
As previously explained, substantially V-shaped profile bottoms may allow the booms 2100, 2200, and 2300 to center themselves. This may prevent them from sliding side to side within one another. This shape may also reduce stress concentration that would otherwise occur at the ninety degree corners of a flat bottom design.
Traditional manufacturing techniques used for steel mechanics cranes do not directly carry over to aluminum cranes. For example, crater cracks tend to form when using traditional welding methods such as MIG (metal inert gas). Traditional welding of tempered aluminum may also result in the loss of temper and therefore a weaker heat affected zone around the weld. To reduce those issues the inventors have used friction stir welding (FSW) as an alternative to traditional fusion techniques. FSW is a solid state process which may avoid melting the material and therefore may maintain much of the original strength. It has a much smaller heat affected zone. FSW doesn't create crater cracks or stress concentrations as may be created using traditional welding techniques.
Designing with a lower strength material also presents a challenge in a confined area. There may not be enough room for the additional material needed for strength. Also, tapped holes may not be an option for high load applications. Structural fasteners in this application used through-holes and bolts with nuts, however, this is not intended to limit the invention.
One more concern with using aluminum is the potential for galvanic corrosion created when steel and aluminum parts are in contact with one another. This corrosion can weaken the structure of the crane as well as damage the appearance. To mitigate these corrosion issues electrically insulating barriers can be placed between the dissimilar metals in vulnerable areas. Minimizing the contact area and also using materials less reactive to one another are other methods used to limit corrosion.
Two main benefits of Applicant's invention in which aluminum is used as the structural material are weight savings and corrosion resistance. Weight reduction increases the carrying capacity of trucks. This may allow for more tools or parts while staying under weight limits. A lighter manual extension (for example, manually moving boom 2100 within boom 2200) decreases the operator effort needed to extend or retract the boom. The natural corrosion resistance of aluminum may help extend the lifespan and maintain the appearance of the crane. Anodizing is one coating option with aluminum that can help retain a new appearance, increase corrosion resistance, increase surface hardness, and electrically insulate.
Initially, the inventor sought to reduce crane weight and increase corrosion resistance while maintaining current cost. Fiberglass composite materials as well as aluminum were two of the alternate materials first investigated. The inventor found early on that aluminum would be more cost effective and gave more freedom in profile design. The first draft of the inventor's design was an aluminum crane using a traditional tube design. The main differences between the inventor's new design and the conventional art were the lack of spacers needed to create the proper clearances between profiles and then being slightly optimized for resistance for bending in the primary load direction. However, the original approach resulted in a disadvantage of having taller than necessary boom and boom profiles only for the purpose of housing the extension cylinder. This problem discouraged the use of aluminum as a material for the crane design. Because the original design utilized a case-fed cylinder, traditional structural members and traditional crane design methods presented no effective way of reducing this section height while keeping the cylinder inside of the booms. Given that the cylinder was to be case-fed for cost and that the cylinder was to be housed inside of the booms for appearance, the inventor departed from traditional crane design concepts and, instead, designed the boom profile around the extension cylinder. Continuing down that path, the inventor realized that all that was necessary was a small opening in the boom profile to allow the mounting of the cylinder rod to boom.
The foregoing is considered as illustrative only of the principles of the disclosure. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the disclosed subject matter to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to that which falls within the scope of the claims.
| Number | Date | Country | |
|---|---|---|---|
| 62552898 | Aug 2017 | US |
