The invention concerns a method of continuously producing a mesh-type support or lattice girder by welding a lower chord arrangement which includes at least one lower chord, in particular two lower chords, and an upper chord which is arranged at a specific height in relation to the lower chord arrangement to at least one diagonal member which extends back and forth between the at least one lower chord and the upper chord, in particular in a zig-zag form, wherein welding of the at least one lower chord and the upper chord to the at least one diagonal member is effected by means of a lower chord welding device and an upper chord welding device.
The invention further concerns an apparatus for continuously producing a lattice girder comprising a lower chord arrangement which includes at least one lower chord, in particular two lower chords, an upper chord arranged at a specific height relative to the lower chord arrangement and at least one diagonal member which extends back and forth between the at least one lower chord and the upper chord, in particular in a zig-zag form, wherein the at least one lower chord and the upper chord are welded to the at least one diagonal member and the apparatus for that welding operation includes a lower chord welding device and an upper chord welding device.
Lattice girders are reinforcement elements prefabricated in the factory for use by prefabrication plants. They are used in prefabrication plants in particular for the production of element slabs (floor slabs, semi-manufactured slabs, filigree floor slabs) and double-shell walls. Lattice girders usually comprise two lower chords comprising generally profiled or ribbed concrete reinforcing steels, two zig-zag-shaped diagonal members which are welded thereto and which comprise generally smooth concrete reinforcement steels and an upper chord which is welded to the diagonal members and which comprises generally smooth concrete reinforcement steels.
Lattice girders are generally available only in certain standard sizes. The characteristic sizes of a lattice girder include in particular the height at which the upper chord is arranged relative to the lower chord arrangement, the length of the lattice girder and the wire diameter of the chords and struts. Only few manufacturers of lattice girders are in a position to meet the specific demands of a customer who is subjecting the lattice girders to further processing. This means that the customer has to accept a series of disadvantages:
There are initial approaches for making the production of lattice girders more flexible in order better to meet the specific needs of a customer who is subjecting the lattice girders to further processing. WO 2005/021181 A1 shows for example a method and an apparatus for producing lattice girders of any length. For that purpose the lattice girders are cut from the continuously produced line of material at predetermined cutting positions. It will be noted however that in this case changing the other dimensions of a lattice girder, in particular the height at which the upper chord is arranged relative to the lower chord arrangement, involves a comparatively high level of complication and expenditure in conversion. Usually production also has to be interrupted for that purpose.
The object of the present invention is to avoid the above-described disadvantages and to provide a method of the kind set forth in the introductory part of this specification, which is simplified and improved over the state of the art, as well as a corresponding apparatus.
According to the invention that object is attained by the features of the two independent claims 1 and 10.
One of the basic ideas of the invention is therefore that the height of the upper chord relative to the lower chord arrangement is changed during the continuous production of the lattice girder. The apparatus according to the invention for which protection is also claimed besides the method according to the invention, for that purpose has a device for height adjustment of the upper chord during the continuous production of the lattice girder. The device for height adjustment of the upper chord can be for example a height-adjustable carrier on which is arranged a holding device for the upper chord. Advantageously that holding device includes a gripper, clamp or another technical solution which is usually employed by a man skilled in the art for that purpose, for releasably fixing the upper chord.
To avoid bending of the upper chord during the change in its height relative to the lower chord arrangement it can be provided that the upper chord is cut prior to such a change in height. For that purpose the apparatus according to the invention desirably includes a cutting device for cutting the upper chord. That cutting device can be arranged for example on the above-mentioned height-adjustable carrier.
A further substantial advantage arising out of the combination of the device according to the invention for height adjustment of the upper chord during the continuous production of the lattice girder and the presence of a cutting device for cutting the upper chord is that ‘ad hoc’ conversion to the production of a lattice girder involving an altered upper chord height is possible without any loss of material worth mentioning. In that case the change in height can be effected completely between two welding cycles (for welding the upper chord to the diagonal members). It is also possible in that way to implement a product-related ‘just in time’ manner of production: more specifically it is frequently the case that, for a given concrete mold, lattice girders of different upper chord heights are required, in differing numbers. It is possible to comply with that wish in timely fashion by the flexible capacity for conversion.
As already stated hereinbefore welding of the at least one lower chord and the upper chord to the at least one diagonal member is effected by means of a lower chord welding device and an upper chord welding device. If now the height of the upper chord relative to the lower chord arrangement is changed during the continuous production of the lattice girder it is advantageous for the angle position of the lower chord welding device and/or the height of the upper chord welding device and/or the angle position of the upper chord welding device to be changed in the course of the change in the height of the upper chord relative to the lower chord arrangement. It is possible in that way to ensure that the welding operation is always effected in the optimum fashion. The apparatus according to the invention, for carrying out those two welding steps, advantageously includes a device for adjusting the angle position of the lower chord welding device and/or a device for adjusting the height and/or the angle position of the upper chord welding device.
It has proven to be particularly desirable if the upper chord and/or the at least one lower chord is fed stepwise to the upper chord welding device or the lower chord welding device respectively. Ideally that stepwise feed is matched to the welding cycle of the two welding devices. For technical implementation of the stepwise feed of the upper chord and/or the at least one lower chord to the upper chord welding device and the lower chord welding device respectively the apparatus according to the invention can for example include an advance device. In the simplest case that advance device is arranged on a linear carriage and is preferably movable by way of an eccentric lever. For releasably fixing the upper chord and/or the at least one lower chord the advance device can include grippers, clamps or other technical solutions which are usually employed by a man skilled in the art for that purpose. If the device for height adjustment of the upper chord includes a height-adjustable carrier it is advantageous for the advance device also to be arranged on that height-adjustable carrier.
To ensure that the upper chord is fed to the upper chord welding device in the optimum fashion it can be provided that the upper chord is centered prior to welding thereof to the at least one diagonal member, in the course of the method according to the invention. For that purpose the corresponding device according to the invention ideally includes a centering device which is preferably equipped with a gripper, clamp or another technical solution usually employed by a man skilled in the art for that purpose, for releasably fixing the upper chord. From a structural point of view it is advantageous for that centering device for the upper chord also to be arranged on the height-adjustable carrier which has already been mentioned a number of times.
The method according to the invention can further be developed by one or more of the following steps and in that way can be categorised in a wider overall context:
To carry out those three method steps the corresponding apparatus according to the invention preferably includes:
Further details and advantages of this invention are described more fully hereinafter by means of the specific description with reference to the embodiments by way of example illustrated in the drawings in which:
a and 3b show two diagrammatic side views of the welding machine to illustrate the stepwise advance of the upper chord and the two lower chords,
a through 4f show a succession of six diagrammatic side views of the welding machine to illustrate the procedure for increasing the height of the upper chord relative to the lower chord arrangement during the continuous production of the lattice girder,
a through 5f show a succession of six diagrammatic side views of the welding machine to illustrate the procedure for reducing the height of the upper chord relative to the lower chord arrangement during the continuous production of the lattice girder,
a and 6b show two diagrammatic side views of the lower chord welding device to illustrate the change in the angle position of that welding device in the course of the change in the height of the upper chord relative to the lower chord arrangement,
a and 7b show two diagrammatic side views of the upper chord welding device to illustrate the change in the height and the angle position of that welding device in the course of the change in the height of the upper chord relative to the lower chord arrangement, and
To produce such a lattice girder 1 the upper chord 3, the two lower chords 2 and the two diagonal members 4 are firstly unwound from drums 7 and 7′ in an unwinding device 22. The chords 2 and 3 and the struts 4 are delivered to the lattice girder manufacturer in the form of wound-on steel wires on those drums 7 and 7′. Depending on the respective nature of the lattice girder type to be produced the steel wires can be of different diameters and/or can involve different surface properties (profiled, ribbed or smooth).
Following the operation of unwinding from the drums 7 and 7′ the lower chords 2 and the upper chord 3 are fed to a straightening machine 23 and the two diagonal members 4 are fed to a bending machine 24. In the straightening machine the lower chords 2 and the upper chord 3 are deformed substantially to form straight bars while the two diagonal members 4 receive a predetermined zig-zag form in the bending machine 24. In that case the lengths L of the individual limbs of that zig-zag form or the bending angle α between the limbs can be freely selected.
Following the straightening machine 23 and the bending machine 24 the lower chords 2 and the upper chord 3 and the two diagonal members 4 respectively are fed to the welding machine 25 in which actual production of the lattice girder 1 is effected by welding the two lower chords 2 and the upper chord 3 to the two diagonal members 4 by means of a lower chord welding device and an upper chord welding device (not visible in this drawing). After they are produced the lattice girders 1 are transported into a storage location 9 by means of a robot device and set down there.
In addition arranged on the height-adjustable carrier 11 is a cutting device 14 for cutting the upper chord and an advance device 15 for stepwise feed of the upper chord and the two lower chords to the upper chord welding device 6 and the lower chord welding device 5 respectively (which can be seen at top right in the drawing). That advance device can be moved towards the right and left by way of a linear carriage 16 and a corresponding guide rail 30 by means of an eccentric lever 17 fixed to the frame 27 of the welding machine 25. The advance device 15 includes a gripper 18 for releasably fixing the upper chord and two grippers 19 for releasably fixing the two lower chords, only one of the lower chord grippers 19 being visible in this drawing (because of the side view). As the height of the upper chord relative to the lower chord arrangement during continuous production of the lattice girder is to be variable the gripper 18 of the upper chord, which is fixed to the advance device 15, is not only displaceable in the horizontal plane but is also adjustable in height. In comparison therewith, it is not provided that the height of the two lower chords is changed. This means that a device 31 for height compensation must be provided between the component on which the two lower chord grippers 19 are arranged and the component on which the upper chord tong gripper 18 is arranged. In the embodiment illustrated here that height compensation is effected by means of rails. In general it should also be noted that the grippers 18 and 19 function just like the gripper 13 arranged on the holding device 12 for the upper chord. The two possible operating conditions are illustrated in the same manner.
Finally also arranged on the height-adjustable carrier 11 is a centering device 20, by means of which the upper chord can be centered, before it is fed to the upper chord welding device 6. That centering device 20 also has a gripper 21 for releasably fixing the upper chord. Stationarily connected to the frame 27 of the welding machine 25 is a holding device 28 for the two lower chords, on which two further grippers 29 are arranged (in relation thereto the same applies as for the other grippers 13, 18 and 19). It should also be pointed out that the upper chord welding device 6 is adjustable in height, as indicated by the two arrows. The precise operating principle of that height adjustment is described in detail precisely like the change in the angle position of the upper chord welding device 6 and the lower chord welding device 5 by reference to
a and 3b serve to illustrate the mode of operation of the stepwise advance, by means of which the upper chord 3 and the two lower chords 2 are fed to the upper chord welding device 6 and the lower chord welding device 5 respectively. In principle this involves the same side view of the welding machine 25 as in
The sequence of the views shown in
Following the operation of cutting the upper chord 3 the lattice girder is transported stepwise towards the right, the advance being effected by means of the advance device 15 in the manner described with reference to
The end position of the upward movement of the height-adjustable carrier 11 is shown in
In a last step (which is to be seen in
Finally attention is also to be directed to the following points:
The succession of the six images of the welding machine 25, shown in
a and 6b and
The left-hand part of the apparatus further includes a wire change device 42, a cutting device 48 and a bending machine 24. They serve to process the diagonal members 4. The diagonal members 4 and the lower chords 2 are fed to the production process at the same height so that they appear to be in superposed relationship as
Upper chords and diagonal members respectively involving different wire diameters can be stored in the wire change devices 41 and 42. In that way it is possible to flexibly vary during the production process not only the height of the upper chord relative to the lower chord arrangement but also the wire diameter of the upper chord 3 and the diagonal members 4 respectively.
Number | Date | Country | Kind |
---|---|---|---|
951/2011 | Jun 2011 | AT | national |
Number | Date | Country | |
---|---|---|---|
Parent | PCT/EP2012/002634 | Jun 2012 | US |
Child | 14134193 | US |