OA12813A

OA12813A - System, method and device for producing a supporting framework or rigid Girder.

Info

Publication number: OA12813A
Application number: OA1200400292A
Authority: OA
Inventors: Ulrich Wallner
Original assignee: Heike Wallner Automation Gmbh
Priority date: 2002-04-25
Filing date: 2003-04-24
Publication date: 2006-07-10
Also published as: BR0309496A; NO20045127L; AU2003232501A1; ZA200409432B; JP4399274B2; ES2282651T3; NO332216B1; EP1497504B1; AU2003232501B2; DE10218597A1; JP2005528541A; DE20215594U1; MXPA04010588A; CA2483531C; WO2003091507A2; KR20050016356A; NZ536705A; WO2003091507A3; ATE354001T1; CN1650074B

Abstract

The invention relates to a system, a method, and a device for producing a supporting framework or a rigid girder comprising rods and connecting elements which are optionally arranged therebetween at connecting points. The rod-shaped elements are respectively made of at least one segment of a material stemming from climbing plants and the connecting elements are made of a solid, re-newable material. According to the invention, the ends of the rod-shaped elements and/or the connecting elements are treated in such a manner that they comprise surfaces extending at least in certain areas along clearly defined geometric bodies such that in the connecting area of a rod-shaped element and a connecting element or another rod-shaped element, each of the bodies comprise respectively a surface which extends at least in certain areas along the covering surface of a cylinder, conical-shaped element, prism or a pyramid and at least partially along a hollow cylinder, conical-shaped element, prism and/or hollow pyramid. Said surfaces are or can be assembled according to a coupling process with adjacent surfaces. The tool used therefor consists of at least one tool embodied as a removing tool, especially as a cutting tool for machining at least one connecting element and/or the ends thereof in order to obtain connectable rod-shaped elements.

Description

01281 3

System, Method and Device for Producinga Supporting Framework or Rigid Girder 5 The invention relates to a System, a method and a device for producing a truss frombar-elements, which are joined or joinable, and from connection-elements located orplaceable between those at their joint places, whereby the bar-elements consist of atleast one segment of a material of high-growing plants each, and the connection-elements consist of a rigid, regenerative material. Preferably, connection-elementsίο are provided wherever two or more bar-elements meet whose longitudinal axes are not coaxial to each other. DE-PS 43 33 029 C2 describes a truss made from bamboo culms, which areconnected to each other via connection-elements, whereby the connection-elements 15 exhibit at least one drill hole each, in which a free end of an unprocessed bambooculm each is inserted, and whereby the connection-elements are die-casted orcasted at frie free ends of the bamboo culm or are fixed at the free ends of thebamboo culm by a glueing or casting agent Thereby the irregularities of the bambooculm are compensated by the die-casting-, glueing- or casting-agent. For this 20 purpose, the drill holes in the connection-elements hâve to be muchoverdimensioned, because the cross-sectional areas of bamboo culms can vary in awïde range. This leads to a huge demand for die-casting-, glueing- or casting-agent.Since, owing to the great volume of the used material, the mechanical properties ofthe die-casting-, glueing- or casting-agent are of high importance for the stability of 25 the framework, besides their adhesive properties, too, a material of very high qualityis required so that the total expenses are heavily increased. Furthermore, theassembly is very work-intensive.

From the disadvantages of the described prior art, there arises the problem initiating 30 the invention, to improve a generic System for producing a truss in such a way, thatthere results an optimum ratio between efforts and achievement, i.e. that the costsand/or the expenditure of work for producing a building can be decreased, without itsstability suffering therefrom. 0128 1 3

At a generic System, the solution of this problem is achieved by the characterisingfeatures of patent daim 1. Preferred Systems can be seen from the daimssubordinated to said daim 1. 5 High growing plants are reinforced with fibres running in longitudinal diredion andtherefore show an optimum stability for (tensile) stress along their longitudinaldirection. On the other hand, since buildings produced by the System according tothe invention are broken up into trusses with nodes and straight connectionsbetween those, it is not required that the bar-elements hâve a high bending strength.îo Therefore, fibres running slantwise or transversal with regard to the longitudinal axisof the bar element, and in particular those running in radial directions or crosswisewith regard to each other, can be renounced. By using regenerative raw materials forthe bar-elements, the use of expensive Chemicals can be saved, which furthermorecorne from fossil and therefore only limited available materials. Furthermore, 15 regenerative raw materials are built up by photosynthesis, whereby the carbon,which is required for a multitude of organic compounds, is abstracted from thecarbon diofcide of the air; therefore, its climate-changing effect as a greenhouse gasis reduced. Biological materials can also be disposed of more easily without pollutionof the environment. 20

For the System according to the invention, it is of central importance that at the jointbetween a bar-element and a connecting element or a further bar-element, each ofboth bodies exhibits at least in a selected area a surface which runs along thesurface generated by a cylinder, cône, prism or a pyramid, as well as at least in 25 another selected area a surface which runs along a hollow cylinder, hollow cône,hollow prism and/or a hollow pyramid respectively. On the one hand, these arebodies which can be produced with relatively simple processes like milling or lathing.On the other hand, this enables a connection by plugging with closely adjoiningsurfaces, which are suitable for a locking by clamping and/or glueing. By utilization of 30 a press fit an even higher strength of the bonding is achievable. For instance, at abar-element a convex hollow element (inside) is always présent within a concavesolid element (outside), so that two standardized surfaces lying in each other can becreated easily by processing the inner and the outer side. If two surfaces, which areapproximately complementary, are created at the connection-element, whereby the 3 012813 convex hollow element is located outside of the concave solid element (core), thenthe potential bonding area and therefore the strength of the joint can beapproximately doubled. Furthermore, a bar-element inserted into the recess iscompletely covered at its face side, and therefore is always firmly pressed to bothbonding areas even during different expansions, e.g. caused by moisture (swelling).

The invention recommends that the two different geometrical shapes, along whichthe surface of a body runs, are aligned concentrically to each other. Such anarrangement of spécial homogeneity can be produced in a very simple way, and, forinstance, it cornes closest to the natural geometry of a bamboo culm.

If the two different, but somehow symmetric shapes, along which the surface of thebody runs, exhibit constant distances from each other, then the resuit is an isotropiestructure, which permits an arbitrary rotation of the bamboo culm around its axis, andtherefore offers an additional degree of freedom to enable a fine adjustment atdifficult nodes of the truss.

The joint of a bar-element with a connection-element can be constructed as a plug-connection to relieve additional locking-means by an intensive positive joint.Clamping joints as well as adhesive joints, for instance with the help of wood glue,can be used as locking means. Additionally to the positive locking of the pluggingconnection, threaded sleeves and/or screwing bolts can be arranged to transmitforces acting along the longitudinal direction of the plugging connection (partially) viaa screwed joint.

For clamping a bar-element at a connection-element or at an additional bar-element,a core, which is integrated there and designed for engagement with the bar-element,can be spreaded and thereby pressed from the inside against the inner side of thebar-element. To spread the core a continually widening element, e.g. of the shape ofa cône or of a frustum of a pyramid, can be pushed or pulled into an inner, preferablycentric recess of the spreadable core. Thereby, this element transforms an actuatingforce of axial direction into a radial deformation of a spreadable core. For thispurpose, connection-element can hâve a cut-out running through its core, into whichthe shaft of a screw, a threaded boit or the like is insertable. The latter dérivés its 4 0 î 28 1 3 axial force from a self-locking twist with regard to another threaded element, whichthereby receives the counter-force appearing during the pulling of an element with awidening cross-section into the core. 5 If a connecting element is in the shape of a ring, then not only bar-elements directedto said connecting element from arbitrary directions within the base plane of the ringcan be accommodated and securely anchored. Moreover, it is possible to prolongthe recesses for accommodation of a screw-like spreading element each as far as tothe inner side of the ring, in order to be able to apply a threaded element or anotherîo clamping element there, which in turn can be comfortably actuated after theconcemed connections hâve been made. However, preferably the longitudinal axesof ail connected bar-elements are directed towards a central point of the connection-element, so that no torque appears in the truss which could lead to flexural stress of the bar-elements. 15

Preferably, a connection-element has a discoid shape, for instance with a circular ortriangular, Quadrilatéral or hexagonal base. Such a connection-element is especiallysuitable for planar trusses, as ail connections lie within one plane there. If, forinstance, a crossbar to a parallel planar truss is to be made, then it is advisable to 20 design these connections not to be perpendicular to a planar truss. The slantedanchoring structures required for this can be accommodated at a variety of locationsat a discoid connection-element, but also at a further connection-element affixed toit. The thickness of such a discoid connection-element should be greater 4han themaximum diameter of a bar-element, so that its ending région is completely 25 embedded into the connection-element. Thereby, if for instance bamboo is used forthe bar-elements, the more sensitive inner side of the bamboo culm is not accessiblefrom outside.

Next to the described embodiment of a connection-element made as one piece, it 30 could also be made from two pièces, so that the two halves initially separated fromone another can be put around a continuous bar-element in order to completelysurround it after joining, and, for instance, to anchor a further bar-element at a placeof a truss where previously no node was présent. In this way such a „half“connection-element can also be fixed to the shaft of a bar-element, e.g. with , 012813 adhesives. For this purpose, such connection-element comprises a concaveconnecting surface which encloses the concerned bar-element partially. In order toproduce such a bonding joint, the concerned area of the shaft of a bar-elementshould be machined at its outer side, too, especially milled to a round shape. 5

It is in the scope of the invention that a bar-element can be inserted between twoconnection-elements, or between two other bar-elements in order to prolong these incoaxial direction. While in the first case both ends of the bar-element should exhibitthe same plug-connection-structure (e.g. annular tongue - annular tongue), it is 10 advisable in the latter case that principally complementary plug-connection-structuresare designated at both ends (e.g. annular tongue - annular groove), so that theresuit are normed bar-elements matching to each other.

Moreover, the invention suggests the utilization of stems, stalks or shanks of high- 15 growing plants, which can be easily processed to elongated éléments for trusses.Besides the Dicotylédones prévalent in Europe, especially the deciduous andconiferous trees, where thin trunks with a diameter up to approximately 10 or 15 cm(so-called weak-wood) are especially suitable, also plants of the species of theMonocotyledones (palm trees, grasses, etc.) can be used, as the vascular bundles of 20 said Monocotyledones are spread so irregularly that no xylem rays appear. As aresuit the fibres are not arranged in a regular pattern side by side. As ail fibres runparallel to each other, a configuration for instance in isogonal rows or even in onesingle ring would lead to layers of bonding agent which are not reinforced, alongwhich a peeling-off, i.e. the formation of cracks would be considerably facilitated. 25 Therefore, such fibreless central or xylem rays should be avoided where possible.Further, an increase of the density of the fibres is désirable from the center to theouter circumference of the bar-element, where naturally the highest forces appear inthe case of still appearing flexural stress. Following this idea of the invention, amongthe family of the Gramineae one will find the so-called giant grasses or bamboo 30 plants, which hâve the further advantage of an increase of vascular bundles orvascular fibres at the outer circumference and therefore feature a high flexuralstrength despite of fibres running in longitudinal direction. Certainly, the stems orstalks of bamboo plants are divided in their longitudinal direction into nodes (nodelevels) and into internodes (tube-like areas). The cross-linking of the fibres at the 012813 6 nodes shall increase the elasticity of the living bamboo; however, in harvested anddried bamboo those can cause tensions, and therefore they should be pierced. Anexcessive impairment of the stability of such bamboo culm is not to be expectedtherefrom. As the internode-segments hâve a structure of extreme homogeneity andas the nodes as centres of growth constitute only thin iayers, the properties of thetubes are dominated by the segments, i.e. the intemodes. Merely the tensile strengthis decreased in the nodes, but not compressive, shear and flexural strength, so thatthe stability of a truss which is predominately subjected to compressive forces doesnot suffer from this.

Some bamboo plants grow within one year to a height of up to 30 meters, while inthe following years only a lignification without additional growth occurs. With thehigh-growing bamboo-plants the diameter of the trunk is between 5 and 20centimètres, and the wall-thickness of the tube is approximately between 0.5 and 8.0centimètres. With the exception of the regularly appearing nodes, Bamboo has nodefects like they are found at Dicotylédones, for instance in the form of startingpoints of branches (so-called knotholes), and which additionally impair the stability.Due to its high mechanical strength, a bamboo culm can absorb high tensile and/orcompressive forces in longitudinal direction, which are comparable to those of steelin the area of the intemodes. The flexural stress is only limited by a tendencytowards the création of bucklings when high flexural forces are applied. Althoughbamboo plants are growing slightly more straight than most types of trees, almostalways inestimable curvatures are présent as well as considérable irrégularitésregardtng the diameter of the tube. For this reason, until now bamboo culms werealways bound together with strings, fibres or the like, which again is absolutelyinsufficient for the production of a framework or truss, as with this no forces inlongitudinal direction of the involved bamboo culms can be transmitted.

As the outside of the stem is covered by a hard, water-repellent and extremelylasting layer, which contains silicates, while the inside bears a wax-like coating, theseareas cannot be wetted by many adhesives and therefore would impair the durabilityof a bonded joint. Furthermore, as these Iayers are relatively smooth, the achievablefrictional connection is relatively low, and so the invention suggests to ablate these 7 012813 layers, but only at an area which is not subjected to the atmosphère so that no watercan enter at the areas which are not protected against moisture anymore.

The shape of the bar-elements themselves may be manifold. According to the 5 chosen material a bar-like structure, i.e. with a massive core like it results forinstance from deciduous or coniferous wood, can be preferred, or a tube-likestructure, which présents itself when using bamboo culms. Furthermore, core drillingof solid log wood bars has the advantage of a steady drying across the diameter withconsequently steady and therefore crack-free shrinking. 10 A further aspect is that bamboo is a biological material, which shrinks or swells underthe influence of its environmental conditions and therefore tends to develop cracks inthe course of time, for example when a rigid end-piece, for instance made from métalor plastic, is inserted. This in tum would hâve disastrous conséquences, as 15 afterwards the water-repellent surface would be interrupted and after that watercould enter and cause rottenness or the like. For this reason, the invention prefersthe use of Connection-elements of a comparable biological material like for instanceDicotylédones, especially deciduous or coniferous wood. Those exhibit similarreactions to changed environmental conditions as Monocotyledones and therefore 20 can shrink or swell in the same fashion, so that the inner tensions in the materialremain comparably low. However, to insure this any intermediate pièces between theMonocotyledone tubes and the connection-elements hâve to be avoided as possible.Therefore, the invention provides a direct joint, either as a plugging, clamping and/ora bonding joint. On the other hand, such joining technique which is industrially 25 applicable with justifiable effort requires standardized contact surfaces, which are notoffered by a naturally grown giant grass. This is remedied by the invention in thatinitially the irregular ends of a bamboo culm which is to be used are treated in such away that surfaces running along well-defined géométrie bodies are created. Thiswork step can be integrated with the aforementioned ablating of the outward surface 30 layers in the proximity of the joining area.

As mentioned before, for the sake of optimal compatibility of a connection-elementwith a bar-element the former can consist of wood. Although wood and bamboo bothare organic materials, they hâve fundamental différences. Therefore also panelling 01281 3 8 matériel made of multi-layer glued bamboo can be used if necessary, so that thematerial properties are identical to that of the bamboo culms.

As the joint element is connected for instance by a sealing adhesive with a tube-like 5 bar-element, for instance a bamboo tube, and features internally connected channelswhich lead to the cavities of the connected, tube-like bar-elements, whereby in thecase of bamboo tubes their nodes are drilled, so a closed cavity with an intentionallyinfluenced sub-climate is created within a framework or truss produced in such way.This sub-climate can be influenced in a multitude of ways in order to control and/orîo monitor the behaviour of the truss, or to keep potentially destroying influences likeinfestation of pests from the inside, fire or the like away from the truss. For this it hasproven pertinent if at least one joint element and/or tube-like bar-element comprisesa port at which gases, foams and/or liquids can be fed into the cavity of the System,for example moist or dry air to keep the bamboo flexible through a controlled climate, 15 further toxins as well as hot, cold or compressed air for pest control, fireextinguishing agents like for instance nitrogen, foams or water or the like.

To solve the set problem, a generic manufacturing process is embodied according tothe characterizing part of the co-ordinated process claim. In the daims subordinated 20 to that further, preferred features of the process according to the présent inventionare described.

The requirement of standardized surface areas which is at first not fulfrfled withnaturafly grown materials, for instance wood or bamboo culms, is indispensable for 25 their employment in the scope of the production of a truss, so that the individualparts fit exactly to each other and are pluggable in the desired way. Furthermore it isof great benefit if also the alignment of the standardized end areas relative to eachother is exactly specified. Especially favourable conditions are created if the endareas are machined in such a way that the géométrie bodies defining their surfaces 30 at least in selected areas exhibit at least one axis of symmetry each which can bearranged in mutual relation, for instance to share a common alignment. Only throughthis it becomes possible to comply with precisely specified angles of inclination ofbar-elements in order to bring them together at predetermined nodes of the truss.These requirements enable the production of trusses according to plan which are 9 012813 calculated in advance with regard to their statics, what is the more important thebigger a building is. Again, the possibility of the use of (wooden) bars and/or(bamboo) tubes of variable length is not impaired, as the machining of the ends cantake place at the construction site after a (tube-like as applicable) bar-element waseut to the desired length. Further, at least one latéral surface area has to be createdat a connection-element, which permits the plugging with a latéral surface of the endof a bar-element. The diameter of this latéral surface and therefore the sélection ofthe tool required for its création is determined by the classification, if applicable, ofthe end of the concerned wooden bar or bamboo tube. As this is determined usuallyonly directly preceding to the mounting of the concerned bar-element, the suitableplug-structure is formed at the concerned connection-element only on the site.

Preferably the bodies and/or surfaces of the parts which hâve to be joined aremachined by ablating, especially by cutting. This technology is equally suitable forbamboo and wood. The tools required for this are handy and therefore they cancomfortably be carried along at a construction side. For this reason, the machining orrework of afready assembled connection-elements is possible, for instance by meansof hand drillïng- or hand milling-machines. Bar-elements like wooden bars or bambootubes are machined before assembly, but after appropriately cutting them to length.Therefor, a clamping apparatus is required.

In order to allow (selected areas of) a latéral surface of a connection structure,especially a core, of connecting éléments (but also of bar-elements which are to bedirectly joined), which are designated for (détachable) clamping joints, a spring likemovement, slots which are preferably parallel to the longitudinal axis of theconcerned plugging connection can be formed in areas close to said latéral surface.These slots can also be designated already in a factory. As a part of the connection-element has to be removed anyway during the (later) preparing of a ring-shapedrecess as a connection structure, an exact radial extension of the slots is notrequired; those just hâve to be sized in such a way that they always reach theconcerned latéral surface.

Previous to the mounting of a bar-element, at such clamping joint first a spreadingelement has to be inserted into a bore directed in parallel or in coaxial alignment to 10 0128 1 3 the longitudinal axis of the connection-element, which can be used after theassembly to exert (radial) pressure to (selected areas of) the concemed latéralsurface in direction of the latéral surface at the end of a bar-element which is to beconnected. 5

After that the bar-elements are plugged together with the concerned connection- orbar-elements and glued or clamped to each other. Naturally, these work steps areexecuted partly in parallel, as almost every nodal connection-element is on the onehand supported by bar-elements, on the other hand it is bearing further bar- îo éléments, so that some connections are formed sooner, others later.

Along the longitudinal edges of a truss or framework, connection-elements are usedas end pièces, which are attachable to a foundation, a ceiling, a roof or the like.These are equipped with a preferably planar base surface having an anchoring 15 facility, for instance one or more bore(s) for passing through mounting screws. A panelling^ or the like can be attached to the joints of a truss to obtain a wall-likestructure, like it is required for example for the construction of houses. While acorresponding anchoring takes place exclusively at the connection-elements, but not 20 at the bar-elements, the latter remain uninjured and therefore conserve their water-repellent properties of their outer surface where applicable, and a cavity containedinside the truss remains sealed. If relatively délicate panellings, for instanceplasterboards, hâve to be fixed to the truss, then either the distances of the nodescan bé reduced, or first a sub-batten is fixed to those, onto which the concerned 25 panelling can be mounted at short intervals.

The inner and/or outer latéral surface at the end parts of a tubular bar-element,especially of a bamboo tube, can be machined. The machining of one latéral surfaceeach, for instance of the outer, may suffice for smaller trusses, while for highly 30 stressable trusses both latéral surfaces at each end of a bamboo tube each shouldbe machined, in order to optimize the stability of each individual connection by anincrease of the potential bonding surface and by an additional positive lock in bothradial directions (inside and outside). 11 012813

By doing so, it has to be taken into account that the radius varies with lumbers orbamboo tubes, additionally, with bamboo tubes or core-driiled lumbers even the wallthickness varies. For instance, considering a 30 m high bamboo tube, the outerdiameter decreases from bottom to top, but especially the wall thickness, too. Due to 5 this réduction of the wall-thickness, usually only the lower 10 m of a bamboo tubecan be used for the purpose of the présent invention. If, for example, this section issawn into single parts with a length of 1.5 m each, then each short bamboo-tube stillhas different wall-thicknesses and eventually different outer diameters. As the casemay be, these déviations can be so significant, that the outer diameter of a eutîo bamboo tube is smaller than the inner diameter of another bamboo tube. Therefore,a common machining with identical tools is out of question. For this purpose, theinvention suggests to create different classes for (the ends of) pièces of bambootubes with regard to their wall thickness and/or regarding their inner and outerdiameter or circumference. In doing so, the (minimum) inner diameter as well as the 15 (maximum) outer diameter can easily be determined with one gauge each. Suchgauges can hâve the shape of a cylinder or of a fiat rectangle (for the inside) or theshape of atiollow cylinder or of a fork (for the outside). Of course, these dimensionscan be measured in different ways also. Each (end of a) bamboo tube is sorted intoa more or less finely graded System of classification, according to which the sélection 20 of the further treatment tool(s) is decided. Thereby, the invention recommends thatthe latéral surface(s) of the end of a bamboo tube are machined in such a way, thatthe wall-thickness of the bamboo-tube is equal to or smaller than a wall-thicknesspreviously selected (according to the System of classification). 25 Before mounting a bamboo tube, eventually présent diaphragms should be bored ormade passable Otherwise in order to create a cavity within the finished truss which isusable for a variety of purposes. To obtain a connection of the cavities of thebamboo tubes which are connected to one connection-element, drillings hâve to bemade, which join inside of the connection-element and which lead to the surface 30 areas of the connection-element covered by a face side of a connected bambootube. On the other hand, if required, the complété cavity of a truss can be dividedinto multiple sections, which can be influenced independently from each other, byusing spécial connection-elements without such continuous channels. Moreover, theboring is intended to provide a homogeneous shrinking of the bamboo tube during 12 012813 the seasoning after the harvesting, and therefore to prevent tensions and therewithcracks in the bamboo.

On the other hand, the diameter of internai channels connecting cavities is entirely 5 independent from the diameter of a wood or bamboo tube which is to be connected.Provided that it is known from the completed design data under which inclinationangles tubular bar-elements meet with a connection-element, the necessaryconnecting channels can be created during the manufacturing of the connectingéléments and thus before their mounting. For this purpose, the raw connection-îo element can be exactly clamped, so that the drillings placed from different sides infact do meet in the centre. For this, preferably a mobile machining centre with guidesof aluminium profiles and multi-axled servo drives is used, which works according tothe spécifications of a design software. The like drillings for the connection of cavitiescan serve as tool-guidings at the construction site during the création of the 15 concemed latéral surface(s) for the connection of one bar-element each. Atconnecting éléments without cavity-connecting channels, drillings may be providedduring their4 production, which are specially intended for the purpose of acting as atool-guiding. 20 If at least one tubular bar-element, especially bamboo tube, and/or preferably atleast one connection-element is provided with a port to the cavity within the tubularbar-elements and connection-elements, different media can be conducted into thiscavity as necessary. In order to permit an exhaustion of a medium which is alreadycontairîed within the cavity, for instance air, it is advisable to always designate at 25 least two such ports at a cavity closed apart from that. Those should be arranged atdistant places to create defined flow conditions. Thereby, it has proven bénéficiai toarrange one such port at the lowest position and as necessary another port at thehighest position of a section of a truss, so that on the one hand liquids, and on theother hand gases each can be completely removed from the cavity. 30

An apparatus for carrying out the process according to the présent invention isdescribed by the characterising features of the independent apparatus claim. 01281 3 13

The utilization of such an apparatus simplifies the production of a truss insofar, asthereby a time-consuming, manual individual treatment respectively rework of thedifferent nodes of the truss can be omitted because surface areas which arecompatible to each other are created. As a machining apparatus according to the 5 présent invention is configured as an ablating tool, especially as a cutting tool, it canbe configured to be mobile due to its small required space, and therefore it can betransported to the construction site without problems.

An apparatus for machining of the ends of a bar-element is characterised by aîo device for clamping a bar-element in such a way, that both of its ends are asconcentrically as possible aligned to a longitudinal axis of the machining apparatus.

Thus, the actual machining-tools always corne across a bar-element which is to beprocessed at one and the same predetermined position, so that they can be adjustedwith regard to the body of the machine in a defined way. Thereby, in general a 15 holding and/or fixing device for each treatment tool is placed at each end of theclamping device. Such a fixing device can, for example, be configured as a slide,which is mdveable in a defined way through a guide in the feeding direction along thelongitudinal axis of the machining apparatus, and which on the other hand is carryingthe actual holding and/or mounting for the machining tool and/or its drive motor. 20 A cutting tool, for example in the form of a milling head, which is configured for thesimultaneously Processing of the inner and outer latéral surfaces of the ends of abar-element, in particular of a bamboo tube, serves for the Processing of the latéralsurfaces at the ends and, for this purpose, is equipped with two separate machining 25 areas, in particular cutting areas. The actual cutting areas can be detachably andthus exchangeably fixed to a base body of the tool, or they can be adjustable withregard to it so that the tool can be adapted to differently classified ends of bambootubes. 30 A preferred apparatus for the machining of a connection-element is characterised bya tool rotating around at least one axis with at least one cutting area for the créationof a rotational symmetric recess of defined cross section. Preferably, the tool can beconfigured to be clampable into a hand drilling machine or the like, in order to beutilizable also for nodal connection-elements which are already mounted in the truss. 14 012813

With a different configuration, the bar-element, in particular a bamboo tube, canrotate, and the tool can be fixed in such a way that it only perforais feed motionsimilar to the fonction of a classical lathe machine.

According to a further aspect of the invention, the cutting area is arranged at aperipheral latéral surface area of the base body of the tool, which encircles a centralguiding device, for example a forward protruding pin. By means of such a guidingdevice, the tool can be centred at a predrilled hole, for instance at a cylindricalguiding recess, in order to assure that the bar-element which is to be inserted exactlytakes up a specified inclination angle, and thus its opposed end is preciselyinsertable into the nodal connection-element there.

Finally, according to the teaching of the invention, the central guiding device isconfigured as a drill, so that the guiding drill hole and the guiding recess can beproduced in one work step. This embodiment is in particular intended for nodes ofthe truss which hâve not been calculated in advance and where no guiding drill holescan be prôduced at the connection-elements in the factory. In those cases thedirection of the plugging connection which receives a bar-element can be adjustedby an assembly mechanic on his own; however, he has to work very carefully inorder to fmd a central cavity-channel and to exactly détermine the right orientation ofthe bar-element.

Further features, details, advantages and effects on the basis of the invention resuitfrom the following description of preferred embodiments of the invention as well asfrom the drawing. There,

Fig. 1 shows a perspective view of the first connection-element of a truss- system according to the présent invention;

Fig. 2 shows a modified embodiment of a connection-element in an illustrationcorresponding to fig. 1 ;

Fig. 3 is a section through two connection-elements according to fig 2 fixed toeach other; 15 012813

Fig. 4 shows a modification of the connection-element from fig 2 in aperspective view; 5 Fig. 5 is an exploded view of a pluggable connection with the connection-element from fig. 4 as well as a partly eut and broken bamboo tube; Fig. 6 shows the composition from fig. 5 after assembly of the connection; îo Fig. 7 shows a different configuration of the invention; Fig. 8 shows a connection-element, which is for instance usable as a base element, in a perspective view; 15 Fig. 9 is a side-view to a planar truss, built with the System according to theprésent invention; $ Fig. 10 shows a connection-element from the truss in fig. 9 in broken and partly 20 eut view, together with a tool applied at a latéral surface to create thecavity for receiving a bamboo tube; Fig. 11 is a longitudinal section through the tool from fig. 10; Fig. 12 25 is a broken side-view to an apparatus for clamping and Processing theends of a bamboo tube; Fig. 13 is a perspective view of a clamping device of the apparatus from fig. 12; Fig. 14 30 is a front view in the direction of the arrow XIV to the tool from fig. 12; as well as Fig. 15 is a section through two coaxially joined bar-elements. 01281 3 16

The perspective view of a connecting element 1 in fig. 1 is intended to illustrate thebasic principle of the présent invention. An arbitrarily or randomly shapedconnection-element 1 exhibits at its surface 2 one or more three-dimensionalstructures 3 for the connection of one bamboo tube 4 each. By assembly of multiple 5 bamboo tubes 4 at such a connection-element 1, the latter becomes a node in atruss or framework 5.

The connection-element 1 from fig. 1 has the basic shape of a rectangularparallelepiped with four equally sized latéral faces 6 and one square top and bottomîo side 7 each. The epipedal-shaped connection-element 1 consists of many layers ofplywood 8 glued on top of each other with crossed direction of fibres each. As theseglued layers of plywood 8 run parallel to the square top or bottom side 7, theconnection-element 1 has a high tensile strength in directions running parallel to those planes. 15 A structure 3 for the connection of one bamboo tube 4 each is arranged at ail sixfaces 6, 7 of the. connection-element 1, so that six bamboo tubes 4 can be broughttogether at such node of the truss, of which two each are aligned with each other andare standing perpendicularly to the plane spanned by the remaining four bamboo 20 tubes 4. Thus a three-dimensional truss is feasible.

As is further shown in fig. 1, each structure 3 for the mounting of a bamboo tube 4has approximately the shape of an annular recess 9 with two bounding surfaces 10,11 in the shape of latéral surfaces of cylinders which are concentrical to each other. 25 The outer diameter of this recess 9 corresponds approximately to the outer diameterof the concerned bamboo tube 4, and the constant distance of the boundingsurfaces 10, 11 with the shape of latéral surfaces of cylinders correspondsapproximately to the standardized maximal thickness of an end area of a bambootube 4 which is insertable into this recess. 30

With the embodiment according to fig. 1, the ends of the bamboo tubes 4 are gluedinto the annular recesses of the connection-element 1, so that a rigid and non-detachable connection is obtained. As fig. 1 further shows, a cylindrical core 12remains within each annular recess 9, which is adhesively connected to the inside of 17 012813 a bamboo tube 4 and thus additionally fixes and stabilizes this bamboo tube 4. Aswood exhibits comparable température coefficients and swelling phenomena due tomoisture as bamboo, a formation of cracks is thus effectively prevented.

Further, each of the cylindrical cores 12 is penetrated by a drilling 13 in itslongitudinal direction. Ail of these drillings 13 join within the connection-element 1and thus create a System of connecting channels between the cavities of ailconnected bamboo tubes 4.

If - as the invention further provides - ail diaphragms of the bamboo tubes 4 arepierced, these cavities are connected with the connection-elements 1 présent acrossthe bamboo tubes 4 and in this way also with ail other cavities of suchlike producedtruss or framework 5. As otherwise the cavities within the bamboo tubes 4 arehermetically sealed by their air-tight outer surface, a purposefully influenceable sub-climate is obtained in the connected cavities of a truss or framework 5 accord ing tothe présent invention. %

For instance, toxins, hot or cold air or other agents for pest control can be conductedinto this cavity to prevent an infestation of pests of such a truss or framework 5,without the utilized agent for pest control ever coming in contact with the outerenvironment. Therefore, the System according to the présent invention has theadvantage that the agents are always highly efficient in the smallest doses,regardless of their composition, without ever affecting the environment. Fora similarpurpose heavy temporal fluctuations of pressure can be created.

Furthermore, this cavity can be filled with a non-flammable gas, for examplenitrogen, under positive pressure, so that in the case of a fire a significant amount ofnitrogen is released at the source of the fire in order to extinguish the burning. At thesame time the sudden decrease of pressure caused by this can be measured inorder to thus infer a fire and to be able to make provisions against a furtherspreading of the fire by conducting water into the cavity. As soon as the fire isextinguished the water can be drained again, and the inner cavity of the truss orframework 5 can be dried again by conducting hot air. 012813 18

The connection-element 14 from fig. 2 has a cubical shape and is modified insofar,as there a structure 3 for connecting a bamboo tube 4 each is provided only at thetop and bottonn side 15, while at the latéral faces 16 oniy central dritlings 17 areprovided which penetrate the connection-element 14. This connection-element 14 5 also consists of layers of plywood 18 giued to each other, which are runningperpendicular to the top or bottom side 15.

The connection-element 14 serves mainly for the extension of bamboo tubes 4. Inorder to also réalisé nodes of a truss with this, two or more such connection-îo éléments 14 are fixed to each other as shown in fig. 3. For this purpose, theconnection-elements are put together in the desired orientation in such a way thatone drilling 17 each is aligned with the other. A screw or threaded boit 19 is insertedin the two aligned drillings and is locked at both sides with a threaded element 20, so that the connection-elements 14 are fixed to each other. 15

Now bamboo tubes 4 can be inserted into the accessible connection structures 3and glued there in the desired manner. This arrangement has the further speciaiity,that at such node of a truss a rotation is possible for adaptation to frameworkstructures running in slanted directions with regard to each other. 20

At the connection-element 1, the bamboo tubes 4 agglutinated to the structures 3 atthe top and bottom sides are only glued to a part of the layers of plywood 8 each, sothat for instance the concerned core 12 and thus the whole bamboo tube 4 could betorn oùt when exposed to high tensile forces. This can be prevented by fixing a 25 connection-element 14 each at the top and/or bottom side 7 of a connection-element1 as required, for instance by means of an inserted and locked threaded boit 19.Thereby, the connection-elements 14 can be aligned in such a way, that theiragglutinated layers of plywood 8 are running perpendicular to the top and bottomside 7 of the connection-element 1 and therefore almost ail layers are glued to the 30 concerned bamboo tube 4.

The connection-element 21 from fig. 4 has the same cubical shape as theconnection-element 14. As with this, the three-dimensional structure 22 for theconnection of a bamboo tube 4 also comprises an annular recess 9 with two bonding 012813 19 surfaces 10, 11 which are concentrical to each other. The core 23 remaining withinthis recess is penetrated by a central drilling 13. However, contrary to theconnection-element 14, the core 23 is provided with two slittings 24 along thelongitudinal axis of the drilling 13, which extend approximately to the base of the core 5 23 respectively of the annular recess 9, so that the remaining quarters 25 of the core can spring to the outside in a limited way.

The central drilling 13 in the core 23 exhibits a conical countersinking 26, in whichthe head of a countersunk screw 27 with a machine thread 28 inserted into theîo drilling can be positioned. A threaded element 29 is screwed on this thread 28 at theouter surface 7 of the connection-element 21 opposite to the connection unit 22.

After the insertion 30 of a bamboo tube 4 into the annular recess 9 this threadedelement 29 is firmly secured. Thereby the head of the screw 31 is pushed deeperand deeper into the conical countersinking 26 and thereby spreads the quarters 25 15 of the core to the outside. Those in tum are pressed with their outsides 11 againstthe inner side 32 of the latéral surface 33 of a bamboo tube 4, clamping it tightly.Therefore, the gluing of a bamboo tube 4 is not required with this type of connection21, and the connection can always be detached in a non-destructive way. Instead ofa countersunk screw 27, a conical boit or the like can be used, too. 20 A further connection-element 34 is shown in fig. 7. This has the shape of an annulus35 with rectangular or square cross-section. At the outer surface 36 of this ring 35 sixthree-dimensional structures 22 are located equidistantiy distributed over thecircumference for the connection of one bamboo tube 4 each. The three-dimensional 25 connection structures 22 are identical to the concemed structures 22 of theconnection-element 21 regarding their topology and function, so that a cross sectionthrough the ring 35 at a connection point 22 rather corresponds to fig. 6, with theexception of the fact that here the crossways running drilling 17 as well as aconnection structure at the inner side 37 of the ring is missing. 30

The ring 35 offers the advantage, that an almost arbitrary number of connectionpoints - only one up to six or possibly even more - can be provided as required,whereby ail connections 22 can be implemented to be détachable. « 012813

With such a ring for instance planar tinsses or frameworks 5 can be produced, likeshown in fig. 9. Thereby, connection-elements 38 of the kind illustrated in fig. 8 serveas base éléments. Those consist of one cuboid 39 each, whose length isapproximately double than its height and width. They feature a central, continuous 5 vertical drilling 40 for the fixing by screws to a foundation 41 or the like. At the area oftheir upper narrow edges 42 a three-dimensional structure 43 is provided each forthe connection of a bamboo tube.

The structure 43 corresponds to the structure 3 of the embodiments 1 and 14îo regarding its fonction, where a bamboo tube is not fixed by clamping, but by glueing.

However, here the annular recess 44 and the drilling 45 concentrical to it are notlocated perpendicular to a surface of the connection-element 38, but inclined underan angle of 30° to the outside diverging from the vertical drilling 40 to the top.Moreover, the structure 43 overlaps the upper narrow edge 42, so that in particular 15 the face side of the core 46 of the connection structure 43 is composed of two partialsurfaces 47, 48 perpendicular to each other, which form a remaining part of theoriginal surface 49, 50 of the connection-element 38. However, this fact does notimpair the fonction of the three-dimensional structure 43 as a connecting and fixationpoint for a bamboo tube 4. 20

As shown in fig. 9, initially a sériés of joint éléments 38 is screwed or otherwise fixedto a foundation 41 in order to build a truss or framework 5. After the connectingstructures 43 are brushed with glue, the ends of bamboo tubes 4 diverging from eachother to the top at together 60° are inserted. Two bamboo tubes 4 are joined at their 25 adjacent upper ends 51 by one nodal connection-element 52 each.

The connection-element 52 forming a node of the truss 5 has a similar base shapeas the connection-element 1, however, unlike that it has a hexagonal base area witha constant thickness, which is greater than the maximum diameter of a bamboo tube 30 4. Like ail other connection-elements 1, 14, 21, 34, 38, this also consiste of layers of plywood crosswise laminated together, whose planes are parallel to the hexagonalbase faces 53. Accordingly, the circumference 54 of such connection-element 52consists of six equally sized rectangles. 21 072813

Before the curing of the glue, adjoining nodal connection-elements 52 are connectedby one bamboo tube 4 running in horizontal direction each, which is glued at thesame time. Thus the first layer of the truss 5 is created. As soon as this is stiffeneddue to the curing of the glue, which can take approximately 15 minutes if wood glue 5 is used, another layer of the truss can be put on it according to the same principle,as it is indicated at in fig. 9. The completed truss 5 consiste of many identical cellswhich hâve the shape of an équilatéral triangle, and obtains thus optimal stability. Ofcourse, another, also three-dimensional structure of a truss 5 can be chosen ifrequired, for instance in the form of two planar and parallel trusses connected toîo each other or the like. Favourably the bamboo tubes 4 always hâve a length of onlyapproximately 1 to 2 m, so that no buckling effects can appear due to a excessive flexural stress at a too long bamboo tube 4.

The node éléments 52 can be individually finished on the spot at the construction 15 site like ali other connection-elements 1, 14, 21, 34, 38. For this purpose, initiallybase bodies 55 of the desired circumferential shape are eut out of a plate ofpreferably wood,. in particular of moulded plywood, which can take place at a factoryor sawmill as applicable. The required connecting structures 3, 22, 43 are thenworked into these base bodies 55 on the spot, even in already mounted condition as 20 required. A cutting tool 56, shown in fig. 10 and 11, serves for this purpose.

The cutting tool 56 comprises a rotating tool-head, which features a connection for adriving engine at the back. The connection can be embodied for instance as acylindrical appendix 58 coaxial to the longitudinal axis of the tool 57, which is 25 insertable into the chuck 59 of a hand drilling machine. With the illustratedembodiment this cylindrical mounting appendix 58 is a part of the shaft of a (wood)drill 60, with which the central cavities 13, 45 of a connecting structure 3, 22, 43 aredrilled. An approximately bell-shaped tool-component 62 is detachably fixed at theshaft of this drill 60 by means of a clamping screw 61. 30

This bell-shaped tool-component 62 consists of a part 63 which is shaped like anannular dise, and a part 64, which is shaped like the latéral surface of a cylinder andextends from the periphery of the first part to the front, carrying at its front side theactual cutting tools 65 for the création of the annular recess 9 of the connection 01281 3 22 ' structure 3, 22, 43. The part shaped like an annular dise has a inner diameter whichcorresponds to the diameter of the drill 60, and an outer diameter, whichapproximately corresponds to the outer diameter of a bamboo tube 4. At its backside66 this part 63 is provided with an appendage 67 of reduced cross-section, but 5 likewise cylindrical-shaped, through which a threaded hole with radiai directionextends to accommodate the clamping screw 61. Thus the part 63 shaped like anannular dise can be plugged over the shaft of a drill 60, whereby it is alignedperpendicular to the longitudinal axis of the drill 57 by means of a fit almost free ofplay, in order to be locked in this position afterwards by tightening the clamping îo screw 61.

The part 64 shaped like the latéral surface of a cylinder can be integrallymanufactured with the part shaped like an annular dise, for instance casted togetherwith the latter, or, for example, it can be produced from a tubuiar part, which is 15 screwed to the part 63 shaped like an annular dise from the backside 66 of this partwith screws 68 parallel to the axis of the drill 57, as shown in fig. 11. In the area of itsfront side the part 64 shaped like the latéral surface of a cylinder is fumished with anumber of equidistantly distributed rectangular recesses, so that approximately theshape of a crown is obtained. 20

At multiple cutting areas 69 of the part 64 shaped like the latéral surface of acylinder, which are parallel to the longitudinal axis of the tool 57, one cutting tip 70each is fixed, préférable with a screw 71 passing through a central bore of theconcerned cutting tip 70. As shown in fig 11, it is the object of this cutting tip 70 to eut 25 the annular recess 9 into the body of a connection-element 1, 1.4, 21, 34, 38 duringthe rotation of the Processing tooi 56 as well as under the influence of asuperimposed feeding motion 72. Thereby, the drill 60, whose front area is locatedbefore the cutting tip 70, can take over a guiding function. 30 With other embodiments of the invention, the recess of the connection structure canbe bounded by bounding surfaces which are overall conical or bevelled at their base;for the production of such recesses the cutting tools hâve to feature an accordinggeometry; if required, the cross-section of the part 64 shaped like the latéral surfaceof a cylinder has to be adapted. 01281 3

As previously explained, the growth of a bamboo tube 4 is always more or lessirregular. As the annular recess 9 of a connection structure 3, 22, 43 according to theprésent invention is optimum round due to the use of a Processing tool 56 revolvingaround an axis 57, normally a bamboo tube 4 cannot be inserted flush with it: Eitherthe bamboo tube does not fit at ail in the designated recess 9, or it is seated muchtoo tight or - if the recess is dimensioned larger - too loose, so that no clampingeffect is created respectively vast quantities of glue are required, which not onlyincreases the costs, but also the labour time due to the increased curing times.

For this reason, the invention provides that the ends 73 of bamboo tubes 4, whichhâve been eut to the desired length, are treated before they are mounted in a trussor framework 5. Therefore, a standardized geometry has to be applied to those, sothat they fit into the designated recesses 9 of the concemed connection-elements 1,14, 21, 34, 38. However, in general this is not sufficient for the production of anexactly pre-planned truss 5, as often both ends 73 of a eut bamboo tube 4 are notcoaxial to each other. This in tum would lead to displacements and/or tensions withina truss 5, which would gradually sum up themselves during the course of theconstruction, so that a bigger building would become more and more skewed withthe progress of the construction. Therefore it is the additional object of an apparatus74 for the machining of the ends 73 of a bamboo tube 4 to assure that not only thetwo end areas 73 of a bamboo tube 4 exhibit surfaces 75, 76 running along latéralsurfaces of cylinders (with other types of connections for instance latéral surfaces ofcônes)' in selected areas, but also that the longitudinal axes of those cylindrical(conical, etc.) areas of both ends 73 are aligned to each other in coaxial relation. Anapparatus 74, which is capable of this, is shown in fig. 12.

In the strict sense, only approximately half of this machine 74 is visible; the left partof the machine, which is laterally reversed with regard to the symmetry plane 77, wasomitted for reasons of space. The machine 74 basically consists of four components:An elongated, rigid profile 78, which is used as a reference for the longitudinal axis ofthe machine 74 as well as for mounting of the further components of the machine.Approximately in the middle of the profile 78 a device 79 for clamping a bamboo tube4, which is to be processed, is mounted to it. At last there are two Processing devices 24 012 8 13 80, which are located at both sides of the clamping device 79, and which are likewisesupported by the profile 78. In the scope of a simpler version one Processing device 80 can be saved if the remaining one can be relocated to the other end of the profile 81 in a simple way, or, for instance, if the clamping device is designed to be rotatable 5 by 180° together with a clamped bamboo tube 4. A commercially available constructional element can be used as the profile 78.Preferably this consists of a four-cornered profile with a square cross-section, whoselong sides 82 comprise a T-shaped undercut mounting groove 83 each, which isîo running along the longitudinal direction of the profile, compare fig. 13. Blocks, whichare not shown, can be mounted at those grooves 83 for example at both end areas of the profile to support the machine 74.

The clamping device 79 comprises two sets of grippers 84 as well as a common 15 actuating mechanism 85. A set of grippers 84 is shown in fig. 13. At both ends of the supporting profile 78, aboit 87, which is parallel to the supporting profile 78, each is fixed in a not rotatablemanner by means of latéral fastening angles 86. Onto those thus fixed bolts 87, 20 there is plugged an upright standing plate 88 each, which comprises a through-holefor this purpose of a diameter corresponding to the diameter of the boit. The plates88 are limited by the concerned fastening angle 86 and are fixed at the other end ofthe concerned boit 87 by a pinion 89 each which is non-tumably fixed to the boit, forinstance crimped, so that they are able to pivot around the concerned boit 87, but not 25 to loosen from it. The plates 88 are embodied as two-armed levers with a shorterarm 90 which protrudes downwards from the concerned mounting hole, and a longerarm 91, which protrudes upward. Both lower lever arms 90 are connected with eachother through a tension spring 92, which is routed under the supporting profile 78,and are thus pulled to each other, until they are stopped by the long side 82 of the 30 carrying profile 78. In a such case, the upper arms 91 of the plates 88 take amaximum spreaded position.

Approxîmately at the upper end of each plate 88, another through-hole is located fora rotating axis 93, which is pivoted there. Each of these rotating axes 93 carries a 01281 3 25 pinion 94 at one end, and, at the other end, a plate 95 whose circumferencecomprises a concave side 96, for instance with a course like a hyperbola.

The gear 94 as well as the plate 95 each are unturnably fixed at the rotating axis 93,respectively crimped, clamped (clamping screw), soldered and/or welded. Otherwisethe pinion 94 is coupled with regard to the rotational movement with the pinion 89 atthe stationary boit 87 through a toothed belt 97, which is kept tense by a device 98.Thus it is achieved that the spatial orientation of the upper plates 95 is keptindependently from the pivoted position of the lower plates 88. This function has thesame effect as a parallel guide by means of a leverage with two pivotable barsparallel to each other.

The upper plates 95 are aligned in such a way, that their concave sides 96 face eachother. Therefore, when the upper lever arms 91 of the lower plates 88 are broughttogether, these sides 96 can approach each other in order to clamp a bamboo tube 4in between them.

An appendix, for instance a screwed boit 99, protruding downwards each is providedat the lower face sides of the lever arms 90 of the plates 88 for the actuation of suchset of grippers 84. Here, the actuating device 85 engages.

The actuating device 85 comprises a pneumatic cylinder 100 which is located underthe supporting profile 78 and which is aligned parallel to it. A conical apex .104, 105each facing axially to the outside is fixed at the casing of the cylinder 101 as well asat the piston through a rod 102, 103 each which is coaxial to the axis of the cylinder.The two rods 102,103 pass through one bearing block 106,107 each, through whichthe complété actuating device 85 is supported at the underside of the supportingprofile 78 so that it is movable in its longitudinal direction in a guided manner.

As the casing of the cylinder 101 itself is not fixed, it can move in the longitudinaldirection of the supporting profile 78 in a limited way. If the pneumatic cylinder 100 isextended pneumatically, the conical apexes 104, 105 move in between the pair ofappendices protruding downside, in particular in between the bolts 99, of one set ofgrippers 84 each, and press those apart. Thus the upper levers 91 are pivoted to the 0128 1 3 26 inside, and the bamboo tube 4 is clamped in the area of both of its ends 73 inbetween two concave brackets 95, 96, each. Thereby, a centrification of the twoends 73 symmetrical to the vertical longitudinal plane of the supporting profile 78takes place, because the conical apexes 104, 105 act evenly on the two arms 90 ofa set of grippers 84. The centrification with regard to the height is obtained throughthe concave shape of the clamping brackets 96. Thereby, the exact dimensions, forinstance the diameter of a bamboo tube 4, are not important, as the pneumaticcylinder 100 moves in the longitudinal direction by itself until equal forces açt on ailarms 90. A bamboo tube 4 centred in such manner is afterwards machined in the area of itsboth ends, i.e. surface areas 75, 76 which are projecting above a predeterminedmeasure are ablated. This is achieved by one machining device 80 each.

Each machining device 80 comprises a slide 108, which is movable along thesupporting profile 78, having a device 109 for mounting a drilling machine 110 undersimultaneous alignment of the drill chuck coaxial to a Processing axis, which isrunning in the centre above the supporting profile 78 as well as at a heightdetermined by that area of the concave clamping brackets 96, which is receded themost.

If the slide 108, which for instance is movable in parallel orientation through latéralrolls 111 engaging into the longitudinal groove 83, is moved to the concemad end 73of a clamped bamboo tube 4, thus the rotational axis of a machining tool 113 whichis clamped into the chuck 112 of the drilling machine 110 remains always coaxial tothe longitudinal axis of the bamboo tube 4, which is predetermined by the previouslyexplained clamping.

The machining tool 113, which acts on the inner and outer side 75, 76 of the bambootube 4 at the same time, is shown in fig. 14 in a front view. It comprises an inner andan outer cutting tool 114, 115, to which the machining of the inner side 75respectively of the outer side 76 of the bamboo tube 4 is allotted. 012813

The inner cutting tool 114 has the shape of a milling cutter, in particular of a shellend mill, with a backward mounting dppendix for ciamping it into the chuck 112. Thiscutting tool 114 enters into the cavity of a bamboo tube 4 in order to process itsinside wall 75 at least in selected areas to a cylindrical shape. 5

Another part is fixed at the shaft of cutting tool 114, which has a bell-shaped formsimilar to the outer part of the tool 56. Although it could be casted integrally forexample, the illustrated embodiment consists of a part shaped like an annular ring116 at the one hand and at the other hand of a cylindrical part 118 which is fixed to îo the first.

At the part shaped like an annular ring 116, a backward, cylindrical appendix 117 islocated which is penetrated by a threaded hole running in a radial direction in orderto accommodate a ciamping screw. With this ciamping screw the part shaped like an 15 annular ring 116 is fixed at the shaft of the cutting tool 114.

By means <?f screws which are penetrating the part shaped like an annular ring 116,this is fixed to the cylindrical part. At the front side 119 of the latter, several teeth 120are eut out, whose edges respectively tips are slightly bent inwards. When feeding 20 the Processing tool 113, the outer surface 76 of the bamboo tube 4 is machined bythese teeth 120 in order to create surfaces which run along latéral surfaces ofcylinders at least in selected areas, and which permit the insertion of the end 73 of abamboo tube into a corresponding recess 9 of a connection-element 1, 14, 21, 34,38. - 25

In order to prevent that the cutting tools 114, 115, which as necessary due to anirregular growth act asymmetrically upon the end 73 of the bamboo tube 4 during thismachining, may generate vibrations of the machining tool 113, this is additionallysupported at the outer latéral surface 121 of the cylindrical part 118. This is 30 accomplished by another trestle 122 fixed to the supporting profile 78, which isencasing the cylindrical part 118 and comprises several, preferably three or four rolls123, which can revolve around rotating axes 124 parallel to the rotational axis of theProcessing tool 113 respectively parallel to the longitudinal axis of the supportingprofile 78. These rolls 123 push against the outer latéral surface 121 of the 28 0128 1 3 machining tool 113 from different sides, for instance from directions displaced by 90°or 120° against each other, so that vibrations are reliably prevented.

When producing bamboo tubes 4 and connection-elements 1, 14, 21,34, 38, 52 5 fitting into each other, it should be kept in mind that the axial length of an end area73 of a bamboo tube 4 machined by ablation is equal or preferably slightly shorterthan the depth of the annular recess 9 in the concerned connection-element 1,14,21, 34, 38, 52 which should accommodate it, so that the area 73 of a bamboo tube 4exposed in this manner, i.e. liberated of its water-repellent coating, is covered by theîo connection-element 1,14, 21, 34, 38, 52 and a layer of glue or the like as applicable.

Besides bamboo tubes 4 also wooden bars 125,126, for instance of weak wood, canbe used as bar-elements with the System according to the présent invention, whichmay either be directly employed as solid wooden bars or can be furnished with a 15 coaxial drilling 127 completely or partly passing through it, for instance in order tofavour a crack-free shrinking during the seasoning.

As necessary, such wooden bars 125, 126 can be put together in coaxial alignmentfor the purpose of elongating them, as shown in fig. 15. For this purpose, the ends of 20 adjoining bars 125,126, which are to be put together, hâve embodiments fitting intoeach other: For example, an annular groove 128 is located at the face side of onebar 125, a complementary annular tongue 129 is located at the face side 126 of theother bar. Together, those form a form-fitting plugging connection, which can.be fixedfor instance by applying glue at the surfaces of a plugging element 128, 129. 25 Besides, it is also possible to press or glue one threaded element each into a central drill hole 127 - a threaded nut in the first and a threaded boit in the other -, so that such bar-elements 125, 126 can also be screwed together- additionally to the form- fitting plugging connection. 29 012813 cfrilf hoie 127 - a threaded nut in the first and a threaded boit in tfte other-, so thatsuch bar-elements 125, 126 can also be screwed together- additionaily to the form-fitting piugging connection.

Claims

30 012813 Claims

1. System comprising bar-elements (4,125,126) joined or joinable to form a truss(5), and connecting éléments (1,14,21,34,38,52) inserted or insertable betweenthese bar-elements (4,125,126) at ail such joint places, where two or more bar-elements meet whose longitudinal axes are not coaxial to each other. whereby a) the bar-elements (4,125,126) consist of at least one segment of amaterial from high-growing plants each, and b) the connecting éléments (1,14,21,34,38,52) consist of a rigid,regenerative material, characterised in that c) at least one end of a bar-element (4,125,126), a connecting element (1,14,21,34,38,52) which is to be mounted to said bar-element, and/orthe end of a further bar-element (4,125,126) which is to be connected,are treated such that they exhibit surfaces running along well-defined 4 geometrical bodies at least in selected areas, d) such that at the joint between a bar-element (4,125,126) and aconnecting element or a further bar-element(1,14,21,34,38:4,125,126), each of both bodies(4,125,126:1,14,21,34,38,52) exhibits at least in a selected area asurface which runs along the surface (11 ;76) generated by a cylinder,cône, prism or a pyramid, as well as at least in another selected area asurface (11 ;75) which runs along a hollow cylinder, hollow corie, hollowprism and/or a hollow pyramid respectively, e) which surfaces permit an assembly by plugging together with closelyadjoining surfaces which are complementarv to each other andsuitable for locking by clamping and/or glueing like a fit.
2. System according to claim 1, characterised in that the joint between a bar-element (4,125,126) and a connecting element or a further bar-element(1,14,21,34,38:4,125,126) is designed as a plug-connection (30).
3. System according to claim 1 or 2, characterised in that the joint between a bar-element (4,125,126) and a connecting element or a further bar-element 31 012813 (1,14,21,34,38:4,125,126) is designed as a clamping (21,34) or glueing(1,14,38) connection.
4. System according to claim 3, characterised in that for mounting a bar-element 5 (4,125,126) by clamping, a core (23) at the connecting eiement or at the further bar-element (1,14,21,34,38;4,125,126) is designed to be spreadable andtherefore said core can be pressed against the inside (76) of the bar-element (4,125,126). io 5. System according to claim 4, characterised in that an eiement (31 ) wideningconically or like the frustum of a pyramid, is pushed or pulled into an inner,preferably centric cut-out (13) of said core (23), for spreading the core (23).
6. System according to claim 5, characterised in that the connecting eiement or 15 the further bar-element (1,14,21,34,38:4,125,126) exhibits a cut-out (13) penetrating the core (23) in which the shaft of a screw (27), of a boit or the likecan be inserted to pull an eiement (31) with widening cross-section into the core(23).
7. System according to one of the daims 4 to 6 characterised in that the connecting eiement (34) exhibits an annular shape (35), so that the cut-outs (13) for the insertion of a screw-like spreading eiement (27,31 ) can extend up tothe inside (37) of the ring (35), in order to apply a threaded eiement or otherdamping eiement at this location. 25
8. System according to one of the previous daims, characterised in that theconnecting eiement (1,52) exhibits a discoidal shape, e.g. with a circular or ring-shaped, or a triangular, quadrilatéral or hexagonal base (7,53).
9. System according to one of the previous daims, characterised in that one connecting eiement (1,14,21,34,38,52) exhibits at least one surface area ofconcave shape, in particular a shape which approximately corresponds to apart of the latéral surface of a hollow cylinder, for connecting to the shaft of abar-element (4,125,126). 32 0128 1 3
10. System according to one of the previous daims, characterised in that at leastone bar-eiement (4,125,126) exhibits a shaft milled to a round shape at its outersurface. 5
11. System according to one of the previous daims, characterised in that a bar-element (4,125,126), which is to be inserted between two connecting éléments (1,14,21,34,38,52), exhibits a principally similar structure at both of its ends, i.e.at both ends the surfaces (11;76) running along a cylinder, cône, prism or îo pyramid are arranged either within or without, respectively, of the surfaces (11 ;75), which run along a hollow cylinder, hollow cône, hollow prism and/orhollow pyramid in a selected area.
12. System according to one of the previous daims, characterised in that a bar- 15 element (4,125,126), which is to be inserted between two bar-elements (4,125,126), exhibits a principally different strudure at both of its ends, i.e. atone end the surface (11 ;76) running along a cylinder, cône, prism or pyramid isarranged within the surface (11 ;75), which runs along a hollow cylinder, hollowcône, hollow prism and/or hollow pyramid in a selected area, at the other end 20 this is the other way round.
13. System according to one of the previous daims, characterised in that the bar-elements (4,125,126) consist of tubes.
14. Process to produce a truss (5) from bar-elements (4,125,126), which are to be joined, and from connecting éléments (1,14,21,34,38,52), which are to beplaced between these bar-elements at ail such joint places, where two or morebar-elements meet whose longitudinal axes are not coaxial to each other. whereby 30 a) the rod-like -éléments (4,125,126) are made from at least one segment of a material from high-growing plants each, as well as b) the connecting éléments (1,14,21,34,38,52) consist of a rigid,regenerative material, characterised in that 33 012813 c) at least one end of a bar-element (4,125,126), a connecting element (1,14,21,34,38,52) which is to be mounted to said bar-element, and/orthe end of a further bar-element (4,125,126) which is to be connected,are treated such that they exhibit surfaces running along well-defined 5 geometrical bodies at least in selected areas, d) such that at the joint between a bar-element (4,125,126) and aconnecting element or a further bar-element (1,14,21,34,38,4,125,126), each of both element bodies(4,125,126:1,14,21,34,38,52) exhibits at least in a selected area a io surface which runs along the surface (11,76) generated by a cylinder, cône, prism or a pyramid, as wel, as at least in another selected area asurface (11 ;75) which runs along a hollow cylinder, hollow cône, hollowprism and or hollow pyramid respectively, e) and that surfaces (11:75) processed in such a way are assembled by 15 plugging them together with closely adjoining surfaces which are complementarv to each other and suitable for locking by clamping< and/or glueing like a fit.
15. Process according to claim 14, characterised in that the bodies and/or the 20 surfaces of the parts (4,125,126:1,14,21,34,38,52) which are to be connected are processed by ablating, particularly by cutting.
16. Process according to claim 14 or 15, characterised in that both ends .(73) of abar-element (4,125,126) are processed in such a way, that the (longitudinal) 25 symmetry axes of the processed areas (75;76) are in line with each other.
17. Process according to one of the daims 14 through 16, characterised in thatslots (24), which are preferably parallel to the longitudinal axis of the concernedplug-connection (3), are placed in an area, which adjoins the latéral surface 30 (11) of a connecting element or a further bar-element (1,14,21,34,38,52:4), in order to facilitate a radial spring-like movement of (areas 25 of) the concernedgenerated surface (11). 34 012813
18. Process according to claim 17, characterised in that a spreading element (31 ) isinserted in a bore (13), which is parallel or coaxial to the longitudinal axis of aplug-connection (3), in order to permit pressure being exerted in the direction of(areas 25 of) the generated surface (75) at the end of a bar-element (4) which 5 is to be connected.
19. Process according to one of the daims 14 to 18, characterised in that the bar-elements (4,125,126) are glued or clamped to the connecting éléments orfurther bar-elements (1,14,21,34,38,52;4,125,126) aller plugging (30) them îo together.
20. Process according to one of the daims 14 to 19, characterised in thatconnecting éléments (38) are used as end pièces along the longitudinal edge ofthe truss (5), which are connectable to a foundation (41), a ceiling, a roof or the 15 like.
21. Process according to one of the daims 14 to 20, characterised in that apanelling or the like is attached at the connecting éléments (1,14,21,34,38,52)of the truss (5). 20
22. Process according to one of the daims 14 through 21, characterised in thatbamboo culms (4) are used as bar-elements, whose inner and/or outer latéralsurfaces (75,76) at the culms' ends (73) are processed.
23. Process according to claim 22, characterised in that the latéral surface(s) (75,76) of the end (73) of a bamboo culm are processed in such a way, that thewall-thickness of the culm (4) is equal to or less than a predetermined wall-thickness.
24. Process according to one of the daims 22 through 23, characterised in that potentially présent diaphragme (nodes) in the bamboo culm (4) are pierced ormade passable otherwise. 01281 3 35
25. Process according to one of the daims 22 through 24, characterised in thatholes (13) are drilled into a connecting element (1,14,21,34,38,52), which leadinto a surface area (12) covered by the face-side of an attached bamboo culm(4), in such a way, that said holes join within the connecting element (1,14,21,34,38,52) in order to obtain a link between the cavities of the attachedbamboo-culms (4).
26. Process according to daim 25, characterised in that, during the création oflatéral surfaces (75,76) at a connection-element which can be plugged togetherwith a bamboo culm (4), the cavity-joining holes (13) drilled into the connection-element (1,14,21,34,38,52) are used as a tool-guiding.
27. Apparatus to produce a truss (5) from bar-eiements (4,125,126), which are tobe ioined, and from connecting éléments (1,14,21,34.38,52), which are to be placed between these bar-elements at ail such joint places, where two or more bar-elements meet whose longitudinal axes are not coaxial to each other. by carrying out the process according to one of the daims 14 through 26,characterised by at least one tool (56,113) designed as an ablating tool, inparticular as a cutting tool, for machining at least one connecting element (1,14,21,34,38,52) made from a rigid, regenerative material and/or the ends(73) of bar-elements (4,125,126) made from at least one segment of a materialfrom high-growing plants each, which are to be mounted to said connectingelement or to one another, in such a way that they obtain .surfaces(10,11,75,76) which run along well-defined geometrical bodies at least inselected areas, whereby at the processed body (4,125,126;1,14,21,34,38,52) inthe area of the joint of a bar-element (4,125,126) with a connecting element(1,14,21,34,38) there is formed simultaneously a surface which runs along thelatéral surface (11;76) of a cylinder, cône, prism or a pyramid at least inselected areas as well as a surface (11 ;75) which runs along a hollow cylinder,hollow cône, hollow prism and or hollow pyramid at least in selected areas,respectively.
28. Apparatus according to daim 27, comprising at least one tool (113) forProcessing the ends (73) of a bar-element (4,125,126), characterised by a » 012813 device (84) for clamping a bar-element (4,125,126) in such a way that both ofits ends(73) are as parallel respectively concentrical as possible aiigned to alongitudinal axis of the Processing apparatus (74).
29. Apparatus according to daim 28, characterised by a device (108) at each endof the clamping device (84) for holding and/or mounting of a processing-tool(113).
30. Apparatus according to one of the daims 27 through 29, characterised by adevice (111) to guide the Processing toois (113) or their holdings (108)respectively in the feeding direction along the longitudinal axis of the Processingapparatus (74).
31. Apparatus according to one of the clams 27 through 30, characterised by atleast one cutting too, in the shape of a milling head (113) for machining thelatéral surfaces (73) at the ends of the bar-elements (4,125,126), which isdesigned to process the inner and the outer surface (75,76) of a bar-element (4,125,126), in particulara bamboo culm, simultaneously.
32. Apparatus according to daim 27, comprising at least one tool (56) formachining a connecting element (1,14,21,34,38,52), characterised by its designas a tool (56) rotating around an axis (57), with a cutting edge for creating acavity (9) of rotational symmetry with defined cross-sectional area.
33. Apparatus according to daim 32, characterised in that the cutting région isarranged at a peripheral boundary surface (64) which surrounds a centricalguiding device (60).
34. Apparatus according to daim 33, characterised in that the centrical guidingdevice (60) is designed as a drill, so that the guiding drill-hole (13) and theplugging cavity (9) can be produced in one work step.