System for joining beams with square or rectangular cross-sections
The invention constitutes of a system for detachable joining of beams with square and/or rectangular cross-section. The system comprises for respective beams, two or more fixing plates mounted in pairs on opposite sides of the beam and fixed along the beam by a friction joint maintained by tightening bolts. Respective fixing plate comprises a first surface the extension of which in at least one direction corresponds to a multiple of a beam width and a second surface turned away from the beam. The system is characterised in that two or more beams are arranged to be joined in perpendicular and/or parrallel directions by at least two opposite each other arranged fixing plates. These fixing plates are arranged to bear on each other along respective second surface. The mutual positions of the fixing plates are fixed by locking elements in through recesses in the each other facing second sides of the fixing plates. These locking elements also constitute anchoring of the tightening bolts.
The invention relates to a system for detachable joining of beams with square or rectangular cross-sections in accordance with the preamble of claim 1.
STATE OF THE ARTSteel beams with square or rectangular cross-sections are common construction elements in high performance static frameworks. In the automotive industry, such beams are used in the foundations of special machines for metal cutting. In the aerospace industry applications are found in jigs for assembling fuselage and wing sections of airplanes. In the processing industry such steel beams are used to support vessels and pipes in specific positions.
Advantageous for said kind of steel beams is:
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- 1. high strength and stiffness relative to their weight
- 2. smooth surfaces facilitating cleaning.
- 3. availability on the market in a great number of sizes.
- 4. relatively low prices.
Disadvantageous for this kind of steel beams is that joints of the beams into frameworks have, until now, not been possible to make with strength values comparable to the capability of the beams, when used in applications where claims also are put on good possibilities of reconstruction and adjustment. It is then a requirement that the fixing devices comply with a combination of properties implying that:
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- 1. they reach a strength comparable with the beams to be joined
- 2. they are detachable.
- 3. they are adjustable.
- 4. they are able to join beams of significantly different dimensions
- 5. they allow different perpendicular or parallel mounting positions
- 6. they are preferably available in the shape of cheap standard components in stock
At present, welded joints is the most common type of joints for tubular steel beams. They are of high strength and could be made at relatively low cost. However, they are not detachable and therefore they don't comply with the requirements for reconstruction. Bolt joints are also common and provide joints of high strength as well. The can be made with bolts through holes in the sides of the beams or through holes in flanges welded to the sides of the beams. The possibility of reconstruction will, however, be heavily restricted by that as a rule new holes have to be drilled for every new mounting position. Thus they don't comply with the requirements for reconstruction.
Friction joints, the field of the present invention, principally result in good possibilities of reconstruction and adjustment. Several successful construction kits for aluminium profiles utilizes friction joints to assemble the parts, which is illustrated in US2001/0025406A1.
In these profiles fixing devices in the shape of for instance anchoring nuts with fastening elements are engaging grooves extending in the longitudinal direction of the profile. The fixing devices can be displaced into optional positions leading to good possibility of reconstruction.
However, the types of friction joints having been developed for joining aluminium profiles cannot be used with steel profiles having square or rectangular cross-section. These profiles are missing the longitudinal grooves where fixing devices can engage. As an alternative for the steel profiles in question friction joints have sometimes been designed with encircling devices that apply force across the cross-section of the beams and thereby create the required friction forces.
Such wholly or partially encircling fixing devices are in some cases formed like yokes that keep steel beams pressed against each other by means of tightening bolts. They are also applied by means of common clamps pressing beams against each other and thereby keeping them interlocked by friction.
The problem with the aforementioned fixing devices is that in the present shape they have large dimensions relative their strength. Therefore in most cases one hasn't been able to provide them with strength values equal to the beams. It hasn't either been possible to give them a general shape to correspond to the demands for variation in applications where possibilities of reconstruction are required. The requirement of connecting a large number of beams of varying dimensions in different mounting positions with a reasonable number of different fixing devices has not been met. For the same reasons keeping prefabricated fixing for this purpose devices in stock hasn't been possible.
DESCRIPTION OF THE INVENTIONAn object with the invention is to solve the problems existing in known solutions for detachable joining of steel beams. This is carried out by a system according to claim 1.
The present invention relates to a modular fixing system for joining steel beams of square or rectangular cross-section for frameworks for supporting functions in machines and other industrial equipment.
Through a combination of locking by friction and locking by shape the fixing system provides a possibility to achieve the strength values corresponding to the requirements in demanding industrial applications. At the same time it gives possibility to detach the joints so that the frameworks can be reconstructed into new structures and also be adjusted to an increased accuracy. Beams of different dimensions and different perpendicular mounting positions can thanks to the modular design according to the thought of the invention be joined into extensive variations of structures for frameworks. By this modular design a reasonable number of different components required in the system can be achieved. In turn this results in that the parts of the fixing system can be manufactured as standard products, whereby the manufacturing cost will be reduced and storing facilitated. The parts can even be stored whereby access for use is achieved at short notice.
The invention is composed of a system of fixing devices for joining beams into frameworks of variable structures for industrial applications. The beams consist of square or rectangular profiles of steel with edge lengths being multiples of a certain module length.
The fixing devices comprises specifically designed fixing plates whose main dimensions constitutes multiples of half the module length. They are mounted in pairs on opposite sides of the beams and are tightened by bolts. The thrust in the bolts provides holding friction forces on the contacting surfaces between the fixing plates and the beams. The holding is further strengthened by stop screws or wedge devices extending from protruding edges or shoulders at the fixing plates and provide a shape determined locking of the beams. Joining locations for beams in frameworks are created by fixing plates at respective beam are put into contact with each other and locked in perpendicular or parallel positions by means of locking elements in the neutral plane between the contacting fixing plates. These locking elements are made of internal threaded sleeves fitting recesses in the fixing plates. At the same time the sleeves provide anchoring of the bolts that tightens the fixing plates to the respective beam.
The invention enables frameworks of high quality to be constructed in variable embodiments by means of a small number of fixing elements of different sizes. They will thereby be of low cost and quickly available for use.
SHORT DESCRIPTION OF THE FIGURES
The design of the invention and further advantages are described more in detail below in connection with the
The secondary alternative for tightening the fixing plates towards each other is illustrated to the right in
Through the secondary joining alternative mounting of beam joints on locations accessible from only one direction is enabled. It also enables that by means of further lengthened bolts joint corners with three or more joined beams can be constructed.
The length of the sleeves 6 and 13 are in the recommended design somewhat shorter than the added up depths of the recesses 10, where they are located. A minor axial play 20 is thus created at the end surfaces 31 of the sleeves 6 and 13 with respect to the bottom surface 32 of the recesses 10. The resisting force to the tightening force in the bolts 3 or 9 will thus in the recommended embodiment of the invention not pass through the sleeves 6 and 13. Instead it passes over the outer surfaces 30 of the adjacent fixing plates and makes these surfaces contacting each other in the parting plane 7. Thereby the position of the beams 2 with respect to their mutual distance is determined by the thickness of the fixing plates. Friction forces are created between the two outer surfaces 30, which contribute to the strength of the joint.
The components of the fixing system are comprised in a superior modular system that increases the possibilities of combinations and reduces the number of varieties of components in the system. This modular system has a common module length m, which in practice can be an even dimension, for instance 50 mm. The width of the beams and a height should be multiples of the chosen module length m and can then be expressed as m*B respective m*H.
From
Another design of the sleeves 6 and 13 that by the sleeves themselves gives a certain distance between the adjacent fixing plates is illustrated to the left in
The number of different fixing plates for covering of the size alternatives in crossing points for beams will thereby be further reduced.
However, the space available for mounting stop screws for shape determined fixing at side forces of the kind described in connection with
Claims
1. System for detachable joining of beams with square and/or rectangular cross-section for respective beam comprising two or more fixing plates mounted in pairs on opposite sides of the beam and fixed along the beam by a friction joint maintained by tightening bolts, whereby respective fixing plate comprises a first surface, the extension of which in at least one direction corresponds to a multiple of one beam width and a second surface turned away from the beam, wherein two or more beams are arranged to be joined in perpendicular and/or parallel directions by at least two opposite to each other arranged fixing plates, which are organized to bear on each other along the respective second surface and whose mutual positions are fixed by locking elements in recessions in the each other facing sides of the fixing plates and which locking elements also constitute anchoring of the tightening bolts.
2. System according to claim 1, wherein the locking elements are made of inner threaded sleeves.
3. System according to claim 2, wherein the fixing plate comprises projections arranged at respective corner of the plate.
4. System according to claim 3, wherein stop screws, extending from the projections are arranged to fix the position of the beams in a transverse direction in the friction joint, whereby a shape determined locking of the beams is achieved.
5. System according to claim 3, wherein wedges, extending from the projections are arranged to fix the position of the beams in a transverse direction in the friction joint, whereby a shape determined locking of the beams is achieved.
6. System according to claim 2, wherein the sleeves have longitudinal slots.
7. System according to claim 1, wherein the beams are tubular beams.
Type: Application
Filed: Jun 4, 2004
Publication Date: Oct 12, 2006
Inventor: Gilbert Ossbahr (Linkoping)
Application Number: 10/559,611
International Classification: E04B 1/26 (20060101);