GB2459432A - Pre-stressed elements of an assembly - Google Patents

Abstract

A sub-frame is pre-loaded, preparatory to assembly with other (pre-loaded or unloaded) elements or sub-frames into larger sub-assemblies, culminating with a full or completed frame assembly, along with junctions, links, transitions or joints between elements and/or sub-assemblies, such as flanges or hinges, between elements. The methodology may be applied to a pre-fabricated collapsible flat-rack container with a platform deck chassis support structure and/or folding end walls. A space frame may comprise longitudinal beams 10 and transverse members (11, 13 fig 1B), the beams having a longitudinal curvature or set. The beams 10 may be subjected to local point pre-stressing at intervals, the levels and timing of which may vary. Various apparatus for pre-stressing elements is shown in for example figures 10, 12, 13, 16, 17 and, 18. These may use multiple jacks 31, which may include rotary crank arms (fig 17B).

Description

Pre-Loading

Background -Prior Art

The Applicant has previously devised pre-loading for pre-stressing of individual beams or elements for subsequent assembly in a pre-fabricated lattice frame. A particular use s is in the manufacture of flat bed containers or so-called flat racks in which a deck features an array of interconnected beams and elements. Generally, longitudinal beams on opposite deck sides are bridged by transverse beams.

Decks are subject to considerable passive or dead weight cargo loads and operational handling and stacking loads so are susceptible to flex and permanent bending set, which taken to extremes can lead to misalignment in handing and stacking fittings.

The rationale of pre-loading is to create a counter-set or curvature which is taken up when the container is put into active service.

Such beam pre-loading is selectively applied at strategic locations along beam length.

Pre-calculated forces are applied locally at a series of target locations for a certain is time period to deform the beam by a prescribed amount. The force applied locally and collectively is sufficient for local bending to achieve a permanent' memory or set'. This is offset upon working loading of the pre-stressed beam in operational use.

Pre-loading has implications not only for the element itself, but for interfaces, (rigid) connections, or joints with other elements. Live' working stresses are accommodated by relieving and/or re-distributing some or all of the stored' pre-loading stress.

Assembly Pre-loading Wholesale composite or synchronised loading of a complete interconnected frame assembly in its entirety, as a containment boundary', but applied over multiple distributed contact points, has also been proposed, but stress distribution is constrained in less predictable ways with less predictable consequences.

Thus conventional frame element interconnections are primarily intended and designed at the outset to achieve a desired frame configuration or layout and combined operational rigidity, rather than to address transfer of pre-loading stresses to preface operational use.

Pre-loading has hitherto been used in the context of the extremes of container pre-fabrication, that is individual elements and completed frame assemblies. In contrast the present invention envisages intermediate frame sub-assemblies of part-completed frames. This poses unique problems not previously addressed. Thus the effect of pre-loading sub-assemblies per se and assembling and possible further pre-loading of multiple sub-assemblies into a complete final assembly. Further loading risks undermining the effect of previous pre-loading, with unpredictable outcomes.

Statement(s) of Invention

The present invention applies pre-loading to a sub-frame, preparatory to sub-frame assembly with other (pre-loaded or unloaded) elements or sub-frames into larger sub-assemblies, culminating with a full or completed frame assembly, along with junctions, links, transitions or joints between elements and/or sub-assemblies, such as flanges or hinges, between elements.

As to what constitutes a sub-assembly is otherwise moot, but the intention is sub-assemblies to which further elements or sub-assemblies are to be secured.

Staging, staggering or phasing pre-stressing from or beyond individual elements, through intermediate combinations of elements, allows greater control over both the application of pre-stressing loads and the internal accumulated stress effect.

Intermediate checks can be made and further correction applied preparatory to continuing assembly.

Elements may be joined before, during or after sub-assembly. In an assembly, locally applied stresses are distributed between and among elements. A prime pre-stressing mode is over the longitudinal span of an elongate beam, between opposite beam ends, with intermediate support and/or bracing. Loading is applied at one or more locations along the beam, typically by individual loading jacks. A splayed, multi-head, bifurcated or offset jack end fitting can be employed to distribute applied pre-load stress to spaced points.

Statement of Invention (2)

A method of pre-loading a sub-frame, preparatory to sub-frame assembly with other pre-loaded or unloaded elements or sub-frames into larger sub-assemblies, culminating with a full or completed frame assembly, along with junctions, links, transitions or joints between elements and/or sub-assemblies, such as flanges or hinges, between elements whereby to introduce and/or retain internal stresses better to accommodate and counter operational loading stress arising.

is A sub-frame pre-loaded by the method.

A pre-fabricated container incorporating a pre-loaded sub-frame.

A collapsible flat-rack configuration container with a platform deck chassis support structure and/or folding end walls pre-loaded by the method.

A method of manufacturing flatrack base, comprising the following steps: (a) Fabricate bottom side rails with upward camber.

(b) Fix cross members transversely between two bottom side rails related in step (a) to form a original flatrack base.

(c) Install corner castings on the original flatrack base related in step (b) according to different types of flatracks.

(d) Place the flatrack base related in step (c) on work beds at four corners, and depress the flatrack base by plural cylinders which distributed by the center of bottom side rails on different points.

The method of manufacturing flatrack base, wherein the step (c) comprising: firstly weld the corner castings at the bottom of fixed hinge plate, then weld the welded corner castings and fixed hinge plate to the two ends of the sill respectively, finally weld the union of the said three parts to the two ends of the bottom side rails of the original flatrack base.

The method of manufacturing flatrack base, wherein the step (c) comprising: weld the corner castings at the bottom of fixed hinge plate, then directly weld the union of welded fixed hinge plate and corner castings at the two sides of the ends of the original flatrack base.

The method of manufacturing flatrack base, wherein the base is jacked up at the middle of two longitudinal sides of the flatrack base before implementing the said step (d).

The method of manufacturing flatrack base, wherein the said flatrack base is jacked up to make the camber be a 3mm-5mm permanent deflection upwards.

The method of manufacturing flatrack base, wherein the said bottom side rails are welded rails, comprising top flange, bottom flange and at least one web which is between the top flange and bottom flange, and the web is an arch with camber.

The method of manufacturing flatrack base, wherein when the said welded rails are shaped, firstly depress or jack up the top flange and bottom flange to an arched plate which conforms with the camber of web, then separately weld the top flange, bottom flange with the top and bottom of web, so the welded bottom side rails have a certain camber.

The method of manufacturing flatrack base, wherein the camber of the web for 4Oft flatrack is 5Omm.-8Omm, while the camber of the web for 2Oft flatrack is 1 5mm-.45mm.

The method of manufacturing flatrack base, wherein depressing the flatrack base on different points in step (d) is finished by several times, the camber of shaped base for 40ft flatrack is 40mm-65mm, while the camber of shaped base for 20ft flatrack is 10mm-30mm.

S The method of manufacturing flatrack base, wherein the said bottom side rails are hot rolled beams and cambered upwards previously so that the bottom side rails have an upward camber.

The method of manufacturing flatrack base, wherein the camber of the bottom side rails for 40ff flatrack is 5Omm-8Omm, while the camber of the bottom side rails for 2Oft flatrack is l5mm-45mm.

The method of manufacturing flatrack base, wherein depressing the base on different points in step (d) is finished by several times, the camber of shaped base for 4Oft flatrack is 4Omm-65mm, while the camber of shaped base for 2Oft flatrack is 10mm-30mm.

Layered Frame Assembly A stacked, layered or tiered frame assembly can be loaded together as a unitary (cohesive) group, with forces applied to or between outermost frames. Intermediate frame sub-assemblies, such as a peripheral outer bounding frame, can be loaded as an entity.

Similarly, even more basic or primitive' frame elements can be loaded individually; such as longitudinal and transverse beams, before joining in a peripheral sub-frame assembly. Intermediate transverse rib or spar in-fill can be loaded individually before fitting within, and joining to, a bounding peripheral sub-frame. Application of local force is distributed throughout the structure. Internal stresses are thus both introduced and adjusted to a new (temporary) medium.

A slight (initial) profile curvature or bow can be introduced by pre-loading. This can settle or flatten out under active working loads in use. The attendant profile change can be used to advantage to achieve a long term desired form; such as a straighter or more rectilinear form, rather than one with a sag or deformation curvature.

Distributed Loading Distributed multi(ple)-point (contact) loading can collectively and cumulatively create a desired loading pattern and thus in turn a derivative internal stress or stress (re-) distribution and stored energy. This can be adjusted or relieved by loading subsequently applied in active use.

Connectors, Junctions or Joints Prospective junctions with other elements or sub-assemblies can be fitted and subject to pre-load, particularly if they or some part of them link elements within that sub-assembly. As overall strength of a completed assembly is contingent upon that of the weakest part, or the weakest joint, the contribution of that pre-loaded joint is material.

A common such joint,, coupling or connector is configured as a flat plate.

For flanged members, loading is conveniently applied to flange faces which present an accessible contact surface. That, said other webs or web faces can be used. In the case of common I-beam structural members, only an accessible, say, top flange need be directly loaded.

Incremental Loading A progressive continuous or incremental (stepped) pre-load can be implemented with frame assembly from individual beam elements through to a lattice grid. Successive step loads might be interspersed with rest' periods to allow internal stress adjustment.

The pattern or profile of applied loading vs time affects accumulated internal stress.

Similarly, the distribution of applied stress affects accumulated re-distribution of internal stress.

Deflection Containment S The profile of a stressed member sets a deflection containment or curtailment boundary' for internal stress, with any interconnected member representing a supplementary external local constraint or diversion routing path.

Thus, as compared with, say, a stand-alone beam pre-stressed as with the Applicant's original formative work, a multi-element or composite beam has somewhat modified freedom' at each point of connection to another frame member.

Overall deflection may differ from an unencumbered' or stand-alone beam. If the connecting frame is orientated with a component opposed to the load and feeds to a support point, it can provide a bracing to deflection.

There is also the opportunity of applying stress loading through and/or between is interconnected members. A connector could thus be used as a route to apply loads to elements to be assembled together.

Closed vs Open Frame An open frame may leave unresolved' elements or limbs free at one (outboard) end, which may not lend themselves readily to pre-loading or rather retention of pre-loads.

With a closed' or bounded frame assembly, with no such loose' ends, greater opportunity for mutual bracing and restraint may arise.

A lattice beam is a common cost-effective wholly or partially closed' configuration for bolstering beam section bending stiffness without undue weight penalty compared to a solid beam. A peripheral or bounding portion is braced by in-fill.

Non-rectangular lattice formats, such as diagonal criss-cross intersection lattice intersection, and/or curved (say, oval or circular) peripheral bounding frames, can be pre-loaded.

Frame Element Interconnection The mode of interconnection has a bearing upon load transfer. In particular any bracing, such as a gusset or flange helps resist relative bending and thus contributes to stiffness of the assembly. On the other hand, say, a pin-jointed connection allows or accommodates relative movement of elements and thus overall assembly flexing, whilst bolstering strength and fatigue resistance.

A combination of elongate struts and plates could be contrived for greater sophistication in stiffness and strength. Plates could themselves be complex forms, such as multi-layer, sandwich or hollow fabricated or extruded forms.

The relative orientation of interconnected elements, for example co-planar or mutually orthogonal, allows local adjustment of behaviour.

Sub-Assembly Interconnection A similar consideration applies to the relative orientation and interconnection of sub-assemblies. In that regard, two or more elements can be regarded as a sub-assembly.

Similarly for two or more sub-assemblies or element and sub-assembly combinations.

Although loading' jacks mounted externally of the structure are convenient, they may also be mounted within' the structure, that is installed (albeit temporarily) in between elements or sub-assemblies and subsequently removed.

Loading Mode or Pattern A continuous, constant or variable, such as phased intermittent or cyclical repeated (pulsating) loading mode or pattern may be achieved by regulating (say hydraulic) power or energisation charge to loading jacks.

Jacks might also be carried upon adjustable or movable mountings, such as eccentric s cams upon a rotary drive shaft as a mechanical means of relative positioning and thus displacement and loading variation. A reciprocating loading could be achieved upon mounting shaft rotation.

Alternatively, or additionally, for relative movement, jacks could be stationary and the subject frames moved or a combination motion performed.

Absolute, or change in, relative disposition of elements upon loading can be used as a raw' indicator to determine loading or induced stress. Figures 19 through 22 sequences lend themselves to this.

Loading Restraints or Deflection Limits It might be contrived that certain elements will touch upon a certain pre-loading, for which a visible check can be made by an operator controlling applied load.

Such inter-element contact might also be used as an initial cushion buffer, ultimate deflection travel abutment limit, or as a trigger' to inhibit jack energisation and further loading. Ongoing loading beyond this might still be countenanced to apply more severe and/or re-directed (say compressive or bending) internal stress.

Displacement or Buckling In the case of a plate element, lateral buckling can be used as a visual loading deflection indicator or limit. Thus, say, juxtaposed plates buckled into mutual contact could serve as an initial limit. Loading within or even in certain instances beyond, elastic limit could be utilised.

When elements are displaced, buckled or deformed under pre-loading, some residual resilience may be relied upon in any inter-element contact. This, rather than a sudden rigid contact and abrupt change in load transfer.

The spacing and bending of (restraint or travel limit) elements could be contrived such that progressively and successively more come into contact upon loading -offering an accumulated buffer resistance. The bending profile could be determined by multiple distributed such loading restraints, which effectively act as local limits, say by disposition in co-operative initially spaced pairs which come into contact upon loading deflection of a carrier beam. Figures 19 through 21 sequences are examples of this.

A combination of deflectable and rigid or (more) obstructive element relative dispositions could be arranged for such deformation modes. Thus, say, certain elements could be set (mutually) orthogonal to others. A strut, brace, link or tie element could be set orthogonal to a plate element, or different plate elements, ties, props or struts set mutually orthogonal. Ties could be semi-rigid rods or flexible cables with fixed or adjustable end mountings.

Load Timing & Phased Element Loading It may well be that in a composite' structure and attendant complex(pre-) loading pattern, elements are differentially stressed according to their disposition, orientation or loading phase.

That is some elements can take a lead or precedence in absorbing the initial effect of applied loading, with other elements in a peripheral support role. Other elements can take up the (pre-)Ioad only after some initial deflection of lead' elements. Relative primary and secondary roles can thus be allocated to elements for pre-loading.

Provision may be made to alter the disposition of elements after initial pre-loading.

Thus local disconnection and re-connection might be contemplated. This along with selective local admission or removal of elements at intervals in the loading phase and any intervening relaxation or recovery stage.

Successive Interleaved Pre-loading and Assembly The invention embraces part-assembly and pre-loading; with further assembly and pie-loading repeated until a full assembly is achieved, with our without final pre-loading. Thus it is unnecessary to complete an assembly before pre-loading. Rather, part-completed and part pre-loaded frame structures are tenable.

Subsequent assembly and pre-loading can be undertaken at different stages and at remote sites. Part-assembled and pre-loaded material can be held or distributed as stock ready to serve different roles in diverse overall assembly forms.

Active' pie-loading by (powered) jacks aside, passive' pie-loading can be contrived by using the inherent mass or weight of a structure. Similarly, temporary cargo load can contribute to pre-loading simply by appropriate local mounting support or capture, such as stacking, hanging or cantilever action. Figures 25A and 25B depict this.

Such passive' loading can be adjusted by interconnecting elements, so some elements carry some part of the passive weight load of others. Overall, elements could carry the entirety of their own weight, some part or all of the weight of other elements, or be relieved of some part of their own weight.

The relative passive and active pie-loads can be adjusted by jacking and/or propping between elements and support structures or jigs and between elements themselves.

Retention elements can be attached to a frame assembly after pie-loading in order to capture or retain internal stress from pre-loading either in whole or in part. Such retention elements could include cables or stays under tension.

Whatever the mode of pre-loading, the active working loads to which a frame assembly is subjected in operational use can act at least partially to relieve stress previously induced by pie-loading. Or put another way, pie-loading can offset, counter or ameliorate the effect of working loads.

Thus deflections or profile changes or departures, such as curvature or bow, from a straight or linear orientation, which would otherwise be associated with or arise from working loads are countered by opposite deflections associated with or arising from pie-loading.

This in turn allows straighter or more rectilinear framework profiles or profiles more consistent with a target profile, such as a flatter format or one without undue sagging deflection or deformation under working loads.

A contribution to stiffness can be achieved by mounting frame assemblies in mutually orthogonal juxtaposition and to which the frame assembly pre-loading technique of the present invention can be applied.

Thus longitudinal and/or transverse frame up-stands can be mounted upon, alongside and/or beneath a deck frame to bolster deck loading capability.

(Supporting) Embodiments There now follows a description of some particular embodiments of the invention, by way of example only, with reference to the accompanying diagrammatic and schematic drawings, in which: Figure 1A shows a space-frame assembly of opposed longitudinal beams with intervening transverse strut bracing intermediate the longitudinal span. The assembly has a modest longitudinal curvature set' or adopts a slightly bowed profile; emphasised visually by reference to a straight broken reference line; that is the actual departure may be exaggerated over reality; Figure 1 B shows a frame assembly of Figure 1 A, undergoing local point pre-stressing at intervals along the longitudinal beams, at points indicated by solid in-fill arrows; again these are merely indicative, rather than necessarily literal or actual positions, similarly with the applied force level which may be uniform or varied over length; similarly, loads can be relatively phased in timing and strength; Figure 2A shows a frame assembly, as a at Figure 1A, but adapted, by installation of side leaf spring control cushions or dampers, for hinged end walls at opposite deck ends; Figure 2B shows a frame assembly of Figure 2A, undergoing pre-stressing at intervals along the longitudinal beams; the intervals can be varied according to frame Figure 3A shows a side elevation view of a frame assembly of Figure 2B with opposite end walls collapse in-folded within the frame depth about hinge assemblies at each beam end; Figure 3B shows a frame assembly of 3A settled flat after pre-loading and with opposite end walls folded out to an upright disposition.

Figure 4A shows a composite side elevation, depicting an individual deck frame and end frame stood upright at one end and stacked deck frames with respective end frames in-folded at the opposite end; Figure 4B shows a plan view of an individual flat-rack in the stack of Figure 4k with end wall in-folded over a base deck; Figure 4C shows an end view of an individual flat rack of Figure 4A with end wall out-folded to stand upright; Figure 4D shows an end view of stacked flat racks of one end of Figure 4A with in-folded end walls; Figure 5A shows a part cut-away 3D depiction of the lattice or open space frame deck and folding end wall flat rack assembly of Figures 3A and 3B; Figure 5B shows a part cut-away 3D depiction of the other end of the frame of Figure 3B to that of Figure SA, so collectively Figures 5A and 5B reflect a completed deck frame for a flat rack; Figure 6A shows an upper three-quarter perspective view of a peripheral deck frame for a flat rack, under pre-load to adopt an initial curvature or set; Figure 6B shows a side elevation of the frame assembly of Figure 6A; Figure 7A shows a view corresponding to Figure 6A, but with longitudinal stringers set within a peripheral deck frame; Figure 7B shows a side elevation of the deck frame of Figure 7A; Figure 8A shows a stack of frame assemblies undergoing pre-loading applied along the top assembly.

Figure 7B shows a stack of frame assemblies undergoing pre-loading from both above and below the stack.

Figure 8A shows a side elevation of a stack of deck frames undergoing pre-loading from the uppermost frame; Figure 8B shows a side elevation of the deck frame stack of Figure 8A undergoing pre-loading from both above and below the stack; Figure 9 shows a co-ordinated frame assembly and pre-loading sequence, starting with spaced longitudinal deck beams and culminating in frame assembly with transverse bridging in-fill beams; Figures 1 OA through 1 OC depict frame loading upon a setting rig with an elongate support bed carriage for movable loading jacks; Figures 1 lAthrough hG depict pre-loading of diverse configuration deck frame assemblies with variant in fill bracing between opposed longitudinal members; More specifically Figure ilAshows corrugated lattice in-fill bracing 16 to longitudinal side beams; Figure 11 B shows diagonal cross-beams ** between longitudinal side beams; Figure 11 C shows a platform deck in-fill between longitudinal side beams; such in-fill could itself be panel subject to pre-loading along with or separately from beam pre-load; Figures 12A through 12D depict variant loading jack formats; More specifically Figure 1 2A shows a screw pillar jack with offset clamp head to bear upon a workpiece; Figure 12B shows a screw pillar jack with selectively dis-engageable clamp head; Figure 12C shows a hydraulic actuator with offset swivel-mounted clamp head; Figures 13A and 13B depict an open area matrix mounting platform rig for jigs, fixtures clamps, restraints and loading jacks juxtaposed with a subject frame assemblies, in this case of continuous curved closed loop format; More specifically Figure 13A shows a perforated jig bed with jacks disposed about the outer circumference of a frame; Figure 13B shows adjustable disposition of a frame upon a mounting platform, with restraint ties ** selectively deployed; thus frame deformation can be curtailed or (re-) directed within the jig; Figures 14 and 1 5A through 1 5F show pre-loading with local frame bracing by plates and struts, including layered or sandwich disposition; More specifically Figure 14 shows a frame with local bracing elements in longitudinal side frames; variant examples of which are detailed in Figures 15A through 15F; Figure l5Ashowsa single sided gusset plate to an I-beam section; Figure 15B shows a reinforcement gusset plate upon a top flange; Figure 15D shows a stacked web gusset plates; Figure 1 5D shows a diverse cluster of gusset plates inboard and outboard of flanges and webs; Figure 15E shows a ribbed gusset plate; Figure 1 5F shows a hollow section gusset element; Figures 16A through 16D show variable phase loading from continuous to cyclical; More specifically Figure 1 6A shows a side elevation of a pre-loaded frame Figure 1 6B shows a temporarily increased loading in one direction; Figure 1 6C shows reversed loading from that of Figure 1 6B; Figure 16D shows reinstated loading in the sense of Figure 16B; Figures 1 7A through 1 7D show movable loading jack mounting arrangements; More specifically Figure 1 7A shows a side elevation of a frame with a juxtaposed overlying loading rig of multiple individual adjustable jacks; Figure 1 7B shows a cross-sectional view of a rotary crank arm mounting of a jack to achieve an eccentric adjustable linear displacement or reciprocatory action; is Figure 17C shows an intermediate jack displacement; Figure 1 7D shows a more extreme jack displacement; Figures 1 8A and 1 8B show a frame loading pattern from one side; using the overhead rig of Figure 17A; More specifically Figure 18A shows an initial loading phase; Figure 1 8B shows a subsequent loading phase; Figures 1 9A and 1 9B show pre-loading between juxtaposed restraint elements fitted outboard of longitudinal deck beams More specifically Figure 1 9A shows an initial pre-loading stage with an interval between restraints allowing some beam flexing; Figure 1 9B shows beam deflection curtailed by abutment of the restrains; Figures 20A through 20C develop the bending restraint proposition of Figures 1 9A and 1 9B, with repeated restraint element co-operative pairs along the side beams; More specifically Figure 20A shows an interval between all restraints preparatory to initial beam loading and bending deflection; Figure 20B shows a reduce interval between some restraints, with others in limiting contact under further beam loading and bending deflection; Figure 20C shows limit contact of all restraints under final beam loading and bending deflection; Figures 21A through 21C show restraints differently orientated to those of Figures 20A through 20C; More specifically Figure 21A shows mutually orthogonal restraint elements disposed along a beam sides for co-operative interaction with a continuous limit bar; in an unloaded condition; Figure 21 B shows the arrangement of Figure 21A under initial loading, with some restraint elements at a limit condition in abutment with the common overlying limit bar; Figure 210 shows further if not full deflection with most if not all restraints in limiting abutment with the common overlying limit bar; Figures 22A through 220 show yet another restraints disposition to that of Figures 20 and 21 sequences; More specifically Figure 22A shows selective installation of restraints along a deck beam in relation to a common juxtaposed overlying (travel) limit bar; this in an unloaded condition; is Figure 22B shows a variant of Figure 22A with additional restraints installed; Figure 22C shows a variant of Figures 22A and 22B with sporadic restraints; Figures 23A through 230 show alternative frame loading and bending arrangements; More specifically Figure 23A shows bending restraint through stacked frames; each frame has an effect upon bending of superimposed underlying and/or overlying frames and thus upon the overall stack deflection; Figure 23B shows bending leverage applied from opposite beam ends; Figure 23C shows cantilever support from one end with bending from the opposite outboard end; Figures 24A through 24C show bending determination through side mounted elements; More specifically Figure 24A shows longitudinal ties alongside a beam, which through which loading could be applied and/or by which loading could be resisted; Figure 24B shows a longitudinal side plate applied to a beam for loading restraint; Figure 240 shows a pre-formed side bar for loading restraint; Figures 25A and 25B show gross distributed beam loading;; More specifically Figure 25A shows a distributed cargo payload sitting upon a pre-loaded beam with counter-curvature; Figure 25B shows the beam of Figure 25A sagging under a cargo load; Generally, the scale and/or proportion of illustration is for adapted for ease of comprehension and so is not necessarily to scale, or uniform scale, with some judicious local exaggeration (or contraction) introduced where convenient.

Thus fitting a large frame illustration on a modest page span is inherently incompatible with clarity of local detail, so selective focus and distortion is used.

Similarly, some simplification is used for ease of illustration; Referring to the drawings: A diversity of frame, frame sub-assembly and pre-loading configurations are depicted by way of example, with a certain self-explanatory simplicity and commonality of form, so not described in detail. Corresponding components are given the same reference.

Forces applied are indicated by solid in-fill single-headed arrows.

Generally, a partial or sub-frame assembly 20 is pre-loaded by multiple discrete, but co-ordinated, applied forces to introduce and (re-)distribute internal stresses, preparatory to active working loading in operational use. Thus the frame has a 3-D disposition in space -as do the applied loading vectors. Load forces not immediately braced or countered by a support frame result in frame bending stress.

A minimalist open format perimeter frame is depicted in Figures 6A through 7B. A frame with certain in-fill is depicted in Figures lAand lB. A rectangular format primary perimeter structure comprises opposed longitudinal side beams 10 with cross-beams 11 at opposite ends. This has basic structural integrity along with bending and torsional stiffness, bolstered by intervening intermediate cross-braces 12 and 13.

Local loading 30 is applied by individual actuators 31, such as linear hydraulic or pneumatic jacks as depicted in Figures 1 OA through 1 OC and are generally represented as bending loads about a point of beam contact in relation to a work-piece counter-brace or support.

For convenience of mounting, multiple jacks depicted in a common mounting bed ** or carriage, with provision for individual jack movement and orientation adjustment.

Jacks can be mounted at opposite frame sides, with a work-piece located within the frame embrace. Loading force and travel regulation for individual jacks can also be imposed, along with harmonisation of loading cycles.

A regulator could be fitted to each actuator for ease of setting and adjustment, or reliance placed upon remote control of applied energisation.

Jack and/or beam sensors (not shown) can be used to determine the level of applied force and consequent member movement. A common jack supply source can be harnessed for commonality of, synchronised or phased loading, but each jack can be individually regulated in down or upstroke force and extent of linear travel.

Primarily traditional rectilinear or rectangular cross-section elements, members and assemblies are depicted, such as might be derived from standard (steel) stockholding rolled or extruded profiles, for ease of sourcing and fabrication, but in principle any form could be adopted.

Phased progressive' loading might be given to more complex or vulnerable member forms, such as hollow round sections, to avoid irredeemable wall kinks or creases. Not all jacks fitted need be activated simultaneously, but rather a pie-programmed loading sequence could be applied.

The jack carriage could be combined upon a bed with a frame support and mounting jig or fixture, to hold frame elements in relative juxtaposition prior to interconnection and/or pre-loading. Automated feed and extraction of frames, co-ordinated with jack deployment, charge and release, could be employed for repetitive tasks.

Pre-loading can be applied between a base plane or support bed and a frame or between frame elements themselves. Temporary bridging elements could be used to span and transfer loads between otherwise remote parts of the frame.

Similarly, supports or braces could be fitted between jacks for additional rigidity in bracing against loading applied to a frame.

With a jack, or opposed jacks, carried upon a frame, some (modest) jack movement relative articulation or spread could be allowed between jacks to follow frame deflection upon applied loading.

Jacks could be carried, say by local clamping in adjustable jaws, between frame elements and allowed to free-float to adjust their disposition and orientation according to relative frame deflection. With a double-action internal mechanism, jack loading could reinforce clamping to framework members.

Jacks themselves could be secured together of upon a jack mounting framework in complex dispositions for pre-loading a subject frame sub-assembly. Similarly, for assembling multiple pre-loaded sub-frames jacks could be deployed between them for further pre-load of the larger assembly.

Component List longitudinal beam 11 end beam 12 cross-brace 13 ribs 14 hinge end wall (folding) 16 corrugated lattice beam 17 hinge 20 sub-assembly 21 frame (sub-)assembly 22 frame stack 23 platform deck pre-load force 31 loading jack 32 screw pillar jack 33 jack clamp arm 34 hydraulic jack frame support and jack mounting bed 41 curvilinear loop frame A method of maunifacti*ring flatrack base

Field of invention

The present invention relates to a proceasing method kr oversize col1psib1e rigidity container paits in transporting cargo, and more particularly to a method of manufacturing flatrack base.

Background of art

in the container industy, flatrack is widely used because of loading & unloading cargo conveniently, and its large carrying capability. Generally, flatrack Includes collapsible ends flatrack and fixed ends t]ntruclc As shown in Ilgure I * it is the collapsible ends flatrack.

As shown in figure 1, the parts of collapsible container mainly comprise base 10', ends wall ii at two ends of base; As shown in figure 2 and 3, base 10' including bottom side rail 101' at its two sides, cross member 102' fixed between two bottom side rails 102', and the end sill 103' at two ends; corner casting 12' at bottom of four ends of base 10'.

Coiasidering protecting cargos and container, the container standards in ISO stipulates that any container's spare parts can not exceed the bounds formed by outside of corner castings when the container is empty, and the space between underside of bottom side rails and horizontal plane can riot exceed 1 l'-j7znm. For the collapsible container base, because of no side wall and top plate structure, the deflection of the base downwards at the effect of loading cargos is often mote than 30mm. Therefore, If ntannfacturing the collapsible container like figure 4, the space between underside of base 10' arid horinrntal plane meets the requirement of container standards in ISO. Despite the fact that the base 10' is within the bounds of the underside of bottom comet castings 12' when the container is empty, the base 10' will become bending when it is loading. Then the base exceeds the bounds of the underside of bottom corner castings 12'. In this case, it will be harm.fizl for the cargo security and container life. Obviously, the design of flat base is inadvisable.

Therefore1 the common technology option is to make the bottom side rail with camber. As shown in figure 5&6, the bottom side rail 101' of base 10' is welded with top flange 1011', bottom flange 1012'and web 1013'.

Making the web 1013'with upward camber a before fabricating. During the using of collapsible container, the base 10' bends downwards as it loading like arrowhead in figure 7 showing. At the same time, the end wall 11' inclines to the container body inside-Though it can ensure that the max downward bending deformation of base 10' iS no more than 6mm required in container standards in ISO about the underside of bottom corner castings 12'.

But because the welding residual stress in welded bottom side rails easily make the said rails plastic deformation under loading, that cause the base 10' and end walls ii' can not resume to the original state when unloading.

Especially the end walls' incline brings The space between the tops of two ends decreases, which become an obstacle for transfening container. At the same tune, due to the decrease of arched degree of the base, the downward bending deformation of base 10' exceeds the underside of bottom corner castings 12' more than 6mtn,whlcb fanned from circle loading. So the space between the tops of two ends decreases further, which become an obstacle for lifting and yarding container, even destroying the cargos or containers beneath. As fbi this technical solution, if inalce the deformation caused by the first loading little affects the future use, it should ensure the dimension of the container in the range of the size standard required in ISO under 1)111 leading back and forth.

So design the base and eM wall strong enough to ensure the stress of container not exceeding the material yield limit when mufl loading. So it will never deform or has little possibility of defonning. But it's quite clear to increase the weight of container itself reduce the height of cargos, increase cost and reduce loading capacity to do that.

Invention content This invention is designed to overcome the shortage of current technology, providing a method for manufacturing flatrack, by which the base will never deform or has little possibility of deforrning, and will not increase the weight of container itself.

In order to achieve the above goal, this invention takes the following technical solution: A method of rnaxtufaauring itatrack base, comprising the following steps: (a) Fabricate bottom side tails with upward camber.

CU) Fix cross members transversely between two bottom side rails related in step (a) to form a original flatrack base.

(c) Install corner castings on the original flatrack base related in step (b) according to different types of flatracks.

Cd) Place the flatrack base Mated in step (c) on work beds at four comets, and depress the flatiack base by plural cylixiders which distributed by the center of bottom side rails on different points.

The method of manufacturing flatrack base in step (c) is difterent according to the different flatracks.

Such as to the flairack with end sill, the said (c) step is: fntly weld the bottom causer castingsl2 at the bottom of fixed hinge plate 13, then weld the welded bottom corner castings 12 and fixed hinge plate 13 to the two ends of the end sill 103 respectively, finally weld the union of the said three parts to the two ends of the bottom side rails 101 of the original flatack base.

But as to the method of manufacturing flatrack with hinge lack fitting longitudinally fixed at the bottom side rails, the above (c) step is: weld the bottom corner castings 12 at the bottom of fixed hinge plate 13, then directly weld the union of welded fixed hinge plate 13 and corner castings 12 at the two sides of the ends of the original flatrack base.

The said method of manufacturing flairack base, thereinto, jacking up the base 10 at the middle of two longitudinal sides to make the camber be a 3mm-'Smin permanent deflection upwards before implementing step Cd) to decrease or eliminate stress.

The said method of nianufacturing flatrack base, therehito, the bottom side rails can be welded beams and hot rolled beams, but the method of manufacturing base is different because of the beams used.

If the said bottom side rails are welded rails, they comprise top flange, bottom flange and at least one web which is between the top flange and bottom flange, and the web is an arch with camber. During the manuihruring, firstly depress orjaclc lip the top flange and bottom flange to sit arched plate which conforms with the camber of web, then separately weld the top flange, bottom flange with the top and bottom of web, so the welded bottom side rails have a. certain camber. Generally speaking, the camber of the bottom side rails for 4Oft flatrack is SOmni-SQmm, while the camber of the bouom side rails for 20ft flatrack is l5mm-45nimn.

Depressing the flatra.ck base on different points in step Cd) is finished by several times, the camber of shaped base decreases corresponding with flatracks of different size.flie camber of shaped base for 40ff flairack is 4Omm-45nun, while the camber of shaped base for 20ft flatrack is 10mm-30mm.

lithe said bottom side rails are hot rolled beams and cambered upwards previously so that the bottom side rails have an upward camber. Generally speakin the camber of the bottom side rails (hot rolled beams) for 4Oft flatrack is 50mm-BOnn, while the camber of the bottom side rails (hot rolled beams) for 20ft flatrack is 1 Smrn-45mm.

Same as adopting welded rails, depressing the flatrack base on different points in step (4) is finished by several times, the camber of shaped base decreases corresponding with flatracks of different size.The camber of shaped base for 40f1 flatrack is 4Omm-.óSnim, while the camber of shaped base for 2011 flatrack is 10mm-3Onun.

Comparing the prior art, the present invention adopts a method of preloading, after the finish of manufacturing base, and before the assembly of cud wall and binge, preloading the base, and make it deform down towards to achieve the designed shape of arch, and then assemble the end wall together with the base according to the size standard required in ISO. The size of the flairack after loading should keep unchanged and should be same as before loading. The essential is to itnprove the elasticity working limit of the base structure by preloading, and. make the designed load within the elasticity working limit. Middug use of this invention can comparatively reduce the weight of flatrack and the height of base (or containers same like collapsible container structure, and its bottom need to arch) when under the same load, thereibre, it incroase the loading weight and voLume efficiently, even with lower cost and better durability.

Brief description of the drawings

In order to further state the present invention relating to the technic method and efficacy fur achieving anticipate elan, the invention illustrates detailed with drawings. The purpose, feature and specialty of the invention will be deeply illustrated, But the drawings supplied only tbr consideration and explanation, not the limitation fur the invention.

The detailed illustration as follows FIG Lisa structure drawing about the prior art oTh flairacic PEG 2 is a base structure thawing about the prior art of a flatracic FIG I is an enlarged drawing of end FIG 4 is a structure drawing about one prior art of a flatracic FiG S is a structure drawing about another prior an of a flatrack FIG 6 is the sectional drawing of prior azt and present invention of flatrack FIG? is the drawing about the deformation of flatrack under loading.

FIG $ is the drawing about the deformation of Ilatrack under unloading.

FIG 9 is the structure drawing of bottom side rail web.

FIG 10 is the structure drawing of base under jacking up FIG 11 is theAdirectionview of the FIG 10 PIG j2 i the structure drawing of base under depressing FIG 13 is the B direction view of the FIG 12.

Each label in drawings is:

Prior art

IO'base 10j'hottotn side rail l0ll'top flange, 1012'bottom flange, lOliweb * 102cross member 103'end sill ll'endw-all 12'bottorn corner casting Present invention base 101 bottom side rail lOlltopf]ange, 1012 bottom flange, 1013 web 103 end sill 11 end wall 12 bottom corner casting 13 fIxed hinge plate 2 work beds 3 oil cylinder Mode of implementing A method of manufltcturing flatrack base as shown in figure 9 to 13, comprising the following steps: (a) Fabricate bottom side rails with upward camber.

(b) Fix cross members transversely between two bottom side rails related in step (a) to fonn a original flatrack base.

Cc) Install corner castings on the original flatrack base related in step (b) according to different types of fiatmcks.

(d) Place the flatrack base related in step (c) on work beds at four corners, and depress the fiatrack base by plural cylinders which distributed by the center of bottom side rails on different points.

The method of installing bottom corner castingsl2 and fixed hinge plate 13 is different according to the diffezeut flatracks.

1, A method of manufacturing fiatraclc with end sill, the above (c) step Is: firstly weld the boftoin corner caatiugsl2 at the bottom of fixed hinge plate 13, then weld the welded bottom corner castings 12 and fixed hinge * plate 13 to the twc ends of the end sill 103 teapedvely, finally weld the union of the said three parts to the two ends of the bottom sjde rails 101 of the original flatrack base.

In addition, in order to dectense or elboinate stress, jacidog up the base 10 at the middle of two longitudinal sides to make the camber be a 3mni'-Sinm permanent deflection upwards before implementing step (d).

2, As for the method of manufacturing flatrack with hinge lock fitting longitudinally fixed at the bottom side [ails, the above (c) step is: weld the bottom corner castings 12 at the bottom of fixed hinge plate 13, then directly weld the union of welded fixed hinge plate 13 and corner castings 12 at the t*v sides of the ends of the original flatrack base.

The same wIth the first method, in order to decrease or eliminate stress, jacking up the base 10 at the middle of two longitudinal sides to make the camber be a 3mrn-5mm permanent deflection upwards before implementing step(d).

The detailed description about each iuanulcturing step as followst Firstly, (a) step is to ftbricate bottom side rail lot with upward camber.

In the invention, the bottom side rails 101 can be welded beams and hot rolled beams, but the method of manufacturing base is different because of the beams used.

As shown in figure 6, if the said bottom side rail 101 is weLded rail, it comprises top flangel 01l bottom flange 1012 and at least one web 1013 which is between the top flange and bottom flange, and the web is an arch with camber, Therefore, the bottom side rails 101 should be manufactured at first if use welded beams. As shown in figure 9, if make the bottom side rails 101 with I section. The web 1 013 should be made an upward camber c(c at first.

And the size of camber "C' is depending on designed load. The camber "c" of the bottom side rails for 40* flatntck is S0znm-8Omm, whilethe camber of the bottom side rails for 2Oftflstrack is lSmtn-45mm. After the said flange 1013 is shaped, firstly depress or jack up the top flange lOll and bottom web 1012 (flat plate) to an arched plate which conforms with the camber of web, then weld the bottom flange 1012 and web 1013 at first, then weld flange 1011 and web 1013 (see fIgure 6). To avoid the basins to be deformation, bornodromous welding, simultaneous welding and synunetry welding are adopted, so the welded bottom side rails 101 have a certain camber. Because of the effect of stress, the camber of welded bottom side rails 101 is a little smaller then the web 1013 before instalied. Therefore, the camber of shaped base for 40ft flatrack is 4Omin-'flSmm, while the camber of shaped base far 20* tlatrack is 10mm-30mm.

If the said bottom side rails are hot rolled beams, camber upwards previous]y so that the bottom side rails have an upward camber. Generally speaking, the camber "c" for 40ft flatrack is 50mm-SOmm, while the camber for 20* flatrack is lSmzn-4Smm. Because of the effect of stress, the camber of welded bottom side rails 10! is a little smaller then the web 1013 before installed. Therefore, the camber of shaped base for 40* flatrank is 4Omzn-65tnm, while the camber of shaped base fbr 20t� flatratk is lOnun-.. 30mm.

It can be known from mechanical common sense that the section of bottom side rafts ca be "C]" section arid CT" section, but it can be calculated from mechanical common sense that I section beam can save more material than a "section beam on the condition of the same resistance to bending. As for the "C"section beam welded, it IS easy to bend sideward at the effect of stress during welding web 1013 and top, bottom flange 1012.

Secondly, 1)) step is to tzaMversely weld cross member between two side rails t form original base.

Thirdly, (c) step is to set different parts on the original base according to the different functions. As for the common collapsible container with end sill like figure 10 showing, tlrstly weld the bottom corner castingsl2 at the bottom of fixed hinge plate 13, then weld the welded bottom corner castings 12 and fixed hinge plate 13 to the two ends of the end sill 103 respectively, finally weld the union of the said thee parts to the two ends of the bottom side rails 101 of the original flatrack base. But as to the other collapsible containers, the hinge lock fittings longitudinally fixed at the bottom side railsiOl, then directly weld the union of welded fixed hinge plate 13 and cont castings 12 at the two sides of the ends of the original flatack base.

To the above operation, there is a great stress in the welded base or original base, so the measure of decreasing or eliniiuating stress wiil be adopted. As shown in figure 10,11, lock the four bottom corner castings of jacking up the center of bottom side rails with oil cylinder, if jacking up the bottol side rails by plural cylinders, it should be distributed by the center of bottom side rails on different points Finally, (d) step: the essential of this method is to improve the elasticity working limit of the base structure, and make the designed load within the elasticity working limit So preloading the base is the core of' this invention. As shown in figure 12,13, place the flatiacic base on work beds at four corners, and depEess the flatrack base by plural cylinders which distributed by the center of bottom side rails on different points. Generally speaking, the camber of shaped base tr 20* flauck is 10mm'-3 0mm., while the camber of shaped base for 44th tlatrack is 4Onim-65tum.