Method and apparatus for manufacturing lattice girders from wires

Abstract

The invention relates to a method for producing lattice girders (1) from wires, wherein the lattice girders (1) comprise: chords, with a lower chord arrangement having at least one lower chord (2), in particular two lower chords (2), and an upper chord (3) which is arranged at a specific height (H) relative to the lower chord arrangement; and at least one, in particular two, diagonal chords (4) which extend, for example, in a zigzag manner back and forth between the lower chord arrangement and the upper chord (3), wherein the wires for the chords are fed in a forward direction (V), and the at least one diagonal chord (4) is welded to the lower chord arrangement and to the upper chord (3), wherein the height (H) is adjusted to produce lattice girders of different heights. In order to achieve efficient production of lattice girders in a simple manner, according to the invention, in order to adjust the height (H) between successive lattice girders (1), a completed lattice girder (1) is positioned with a feed-side end (6) at a cutting position (5), whereupon the height (H) is adjusted, after which the completed lattice girder (1) is severed, and the severed wires are retracted in a reverse direction (R) in order to produce the next lattice girder (1) with the adjusted height (H). The invention also relates to an apparatus for carrying out such a method.

Description

[0001] Method and apparatus for manufacturing lattice girders from wires

[0002] The invention relates to a method for manufacturing lattice girders from wires, wherein the lattice girders comprise chords with a lower chord arrangement having at least one lower chord, in particular two lower chords, and a top chord which is arranged at a certain height to the lower chord arrangement, as well as at least one, in particular two, diagonal chords running back and forth between the lower chord arrangement and the top chord, for example in a zigzag pattern, wherein the wires for the chords are fed in a forward direction and the at least one diagonal chord is welded to the lower chord arrangement and to the top chord, wherein the height is changed to manufacture different lattice girders.

[0003] Furthermore, the invention relates to a device for manufacturing wire lattice girders, wherein the lattice girders comprise chords with a lower chord arrangement having at least one lower chord, in particular two lower chords, and an upper chord which is arranged at a certain height relative to the lower chord arrangement, as well as at least one, in particular two, diagonal chords running back and forth between the lower chord arrangement and the upper chord, for example in a zigzag pattern, in particular for carrying out a method of the above type, comprising a wire reservoir, at least one transport device for feeding the wires for the chords from the wire reservoir in a forward direction, and at least one bending device for bending the wire(s) for the diagonal chord.at least one bottom chord welding device for welding the diagonal chord to the bottom chord assembly and at least one top chord welding device for welding the diagonal chord to the top chord and a cutting device for cutting a constructed lattice girder to length.

[0004] Lattice girders with a bottom chord arrangement consisting of two parallel bottom chords, a top chord typically positioned centrally but higher between them, and two diagonal chords connecting one of the bottom chords to the top chord and running in a zigzag pattern between the bottom chord and the top chord, are used, for example, in the production of precast concrete elements for buildings. Depending on the type of precast concrete element being manufactured, the height between the top chord and the bottom chords varies and must be adjusted during production. Different wire gauges may also be used when adjusting the height. Manufacturers of precast concrete elements have the necessary equipment to produce the lattice girders on-site according to current demand.

[0005] Changing the height between the bottom and top chords presents several challenges. First, the necessary device should be as simple as possible to ensure cost-effectiveness. Furthermore, the process should be designed to minimize waste. Finally, cycle times for manufacturing lattice girders should be short. In particular, height changes should be relatively quick to avoid production downtime.

[0006] It is known from the prior art to manufacture truss girders using appropriate devices with a continuous wire feed. For example, a device from the company Filzmoser, designated GH300 / 400 "Truss Girder Welding Line GH300 / 400", is known, which enables the production of truss girders with a continuous wire feed. The individual wires for the bottom chord, diagonal chords, and top chord are fed continuously, with the wire for the diagonal chords being bent. The diagonal chords are welded to the bottom chords and top chord using a bottom chord welding device and a top chord welding device. Once a truss girder of the desired length has been produced, it is advanced to a cutting position and then cut or deflected there by a cutting device.Until the wires are cut to length, they are pulled along by the lattice girder, although the wires for the diagonal chord are no longer bent. After the lattice girder is cut to length, the process starts again. However, this results in wire waste, as the wire sections pulled along by the lattice girder up to the cutting position must be cut off.

[0007] From WO 2013 / 000551 A1, a further method for the continuous production of lattice girders and a device for this purpose are known. The device is designed such that a cutting device is provided on the infeed side and a device for adjusting the height of the top chord is also included. When this device is operated, a manufactured lattice girder is cut at the top chord before the height is adjusted. This makes it possible to produce essentially waste-free, since work can continue at the position of the cut wires after the height adjustment. However, this requires a relatively high level of design complexity, as a manufactured lattice girder is cut at the infeed side and the height adjustment for the top chord and the associated top chord welding device is carried out separately.

[0008] This is where the invention comes in. The object of the invention is to provide a method of the type mentioned above with which lattice girders of different heights can be manufactured in a simple manner with essentially no waste.

[0009] A further objective of the invention is to provide a device of the type mentioned above with which lattice girders of different heights can be produced in a structurally simple manner with essentially no waste. This methodological problem is solved when, to change the height between successive lattice girders, a completed lattice girder is positioned with its feed-side end at a cutting position, whereupon the height is changed, the completed lattice girder is cut, and the cut wires are drawn back in a reverse direction to produce the next lattice girder with the changed height.

[0010] An inventive method allows for the structurally simple production of lattice girders of varying heights with virtually no waste. For this purpose, the lattice girder is positioned at a cutting position and cut at this position using one or, optionally, several cutting devices. This process cuts through the bottom chord assembly, the top chord assembly, and the diagonal chord(s). However, before the individual chords are cut, the height is adjusted so that the lattice girder, which is yet to be cut, remains connected to the individual wires at the feed-side end. Thus, the wires are held in place at one end of the lattice girder during the height adjustment, which is a structural advantage. Furthermore, cutting at the cutting position can be performed using one or more discharge-side cutting devices, which is preferred for space reasons.The outgoing cutting devices can be positioned at approximately the same height in the wire flow direction at the cutting position. Preferably, no cutting devices are provided on the incoming side. After the produced lattice girder is cut, it is free at both ends. The incoming wires are then drawn in backwards to produce the next lattice girder at the adjusted height. The next lattice girder can then be produced, and the process repeats, again with the adjusted height. The adjusted height can be greater or less than the previously set height. Although drawing the wires in backwards does not provide a continuous, uninterrupted movement of the wires, this apparent disadvantage is more than compensated for by the simple design and the elimination of wire waste.

[0011] The cutting position is the position at which a fabricated lattice girder, whose first, leading end is free, is cut to length or cut at the opposite, feed-side end. For this purpose, the fabricated lattice girder can be moved forward with its feed-side end to the cutting position. No welding takes place during this forward movement. In this case, a bottom chord welding unit, like a top chord welding unit, is passive. This also applies to a bending unit used to bend the diagonal wire(s). However, the fabricated lattice girder remains connected to the wires required for the individual chords on the feed side during the forward movement and pulls these wires along with it. After the lattice girder is cut, the individual wires are then retracted.By moving forward to a cutting position, one or more cutting devices can be positioned on the outgoing side at the cutting position to cut the belts.

[0012] The cut wires are preferably drawn into a wire reservoir. This wire reservoir typically comprises several spools or coils on which the wires are stored and from which they are supplied. The coils are connected to motors that can rotate them in the opposite direction to the feed motion, thus drawing in the wires. It is further preferred that the wires are fed from a wire reservoir. This wire reservoir can also include spools or coils that are held in reserve and are only used when other wire diameters are required.

[0013] After a completed lattice girder is cut, the cut wire for the top chord is preferably pulled in up to a top chord welding unit. Similarly, the cut wire(s) for the bottom chord are pulled in up to a bottom chord welding unit. The cut wire(s) for the diagonal chord can be pulled in up to a bending unit. If the individual wires are located in the area of ​​the top chord welding unit, bottom chord welding unit, and bending unit, the creation of the next lattice girder begins, which will have a different height than the previously created lattice girder if the height has been changed. The individual positions (top chord welding unit, bottom chord welding unit, bending unit) thus represent the starting position when lattice girders with a different height are to be created after a height change.During ongoing operation, when vertical beams of the same height are created, they are cut off at one end using one or more cutting devices on the outward side.

[0014] As mentioned, the wire reservoir's spools or coils are designed for threading the wires. This offers a further advantage when changing to a different wire diameter. In this case, a wire can be completely pulled through, and a new wire with a different diameter is threaded and fed in. If necessary, several wires can be changed before the next lattice girder is created.

[0015] It is further preferred that the cut wire(s) for the diagonal chord are bent before being welded to the top chord, and that bending of the wire(s) for the diagonal chord is stopped before welding a lattice girder when the height is changed. After cutting and retracting the wire(s) for the diagonal chord(s), preferably to the bending device, bending can be resumed for the next lattice girder to be produced.

[0016] The further objective of the invention is achieved if, in a device of the type mentioned at the outset, the device has an adjustment device for adjusting the height before the constructed lattice girder is cut to length.

[0017] An apparatus according to the invention offers the advantage of a simple design. In particular, one or more discharge-side cutting devices can be used in the usual manner, which allows for a simple design. The corresponding cutting devices are arranged in the same position on the discharge side both during operation when producing lattice girders of the same height and after a height adjustment. Furthermore, if the wire reservoir is configured to draw wires into a reverse feed mechanism, wire waste can be essentially avoided. In addition, only one feed device is required for each wire.The wire feed devices are arranged, in the direction of wire flow, upstream of the bending device for bending the wire(s) for the diagonal chord, the at least one lower chord welding device for welding the diagonal chord to the lower chord assembly, and the at least one upper chord welding device for welding the diagonal chord to the upper chord. The wire(s) can thus be retracted for height adjustment without having to rethread a wire.

[0018] Preferably, a feed device is provided with which the manufactured lattice girder can be moved forward with its feed-side end to a cutting position. During the feed, the fixed, feed-side end of the lattice girder remains connected to the individual wires for the chords. After adjusting the height and cutting the lattice girder at the feed-side end, the wires are free and can be retracted to the desired positions. For this purpose, a pulling and control unit is preferably provided with which cut wire for the top chord can be retracted to a top chord welding device and positioned there with a free wire end. Similarly, a pulling and control unit can be provided with which cut wire for the bottom chord arrangement can be retracted to a bottom chord welding device and positioned there with a free wire end.Furthermore, a drawing and control unit can be provided analogously, with which cut wire for the diagonal belt arrangement can be drawn in up to the bending device.

[0019] Furthermore, the coils for the individual wires can be designed so that the wires can be completely retracted onto the coils. This allows for easy wire replacement.

[0020] The individual drawing and control units can be designed so that the coils are configured to move both clockwise and counterclockwise, for which the coils are appropriately mounted and for which motors are provided that are appropriately controlled. Furthermore, the drawing and control units can each include one or more sensors with which position detection of the cut wires, in particular their free ends, is possible.

[0021] The device according to the invention is particularly designed for carrying out a method according to the invention. Conversely, a method according to the invention is preferably carried out with a device as described above and below.

[0022] Further features, advantages, and effects of the invention will become apparent from the exemplary embodiment described below. The drawings referred to therein show:

[0023] Fig. 1 shows a schematic representation of a device for manufacturing a lattice girder;

[0024] Fig. 2 shows a conversion process to a lattice girder of lower height; Fig. 3 shows a conversion process to a lattice girder of greater height.

[0025] Figure 1 schematically depicts a device for manufacturing a lattice girder 1. The lattice girder 1 typically comprises two bottom chords 2, a single top chord 3, and two diagonal chords 4, which connect the top chord 3 to the bottom chords 2. Due to the schematic representation and the side view in Figure 1, only one bottom chord 2 and one diagonal chord 4 are visible at any given time. The bottom chords 2 together form a bottom chord assembly and can be considered the base. The top chord 3 is located opposite this base. The distance between the bottom chord assembly and the top chord 3 determines a height H. In plan view, the top chord 3 is typically positioned centrally above the bottom chord assembly and thus has the same distance to both bottom chords 2.

[0026] For the production of a lattice girder 1, wires are required, which are fed via a wire reservoir 7 (not shown in Fig. 1). To move the wires in a forward direction V, an upper chord feeder 12, a lower chord feeder 13, and a diagonal chord feeder 14 are provided. The wires are transported in the forward direction V by the corresponding feeders. Furthermore, the device includes an upper chord welding device 8, a lower chord welding device 9, and a bending device 10. The wires for the diagonal chord 4 are bent by the bending device 10 so that a diagonal chord 4 can connect a lower chord 2 to the upper chord 3. For this purpose, the upper chord welding device 8 and the lower chord welding device 9 are provided, which connect the diagonal chord(s) 4 to the upper chord 3 on the one hand and the lower chord 4 on the other at the corresponding positions.The lattice girder 1 is formed by welding the straps together. As soon as the welding process is complete at one point, the lattice girder 1 is advanced again. This continues until the lattice girder 1 reaches the desired length. Once this length is reached, the lattice girder 1 can be cut. A cutting device 11 is provided for this purpose. With the cutting device 11, the lattice girder 1 is cut to length at a feed-side end 6 in a cutting position 5. After cutting, the lattice girder 1 is also free at the feed-side end 6 and can be removed. Meanwhile, the next lattice girder 1 is already being manufactured if it is to have the same height H.

[0027] However, it may be necessary to require lattice girders with a different height H for other precast concrete elements. In this case, a height adjustment is required. Figures 2 and 3 illustrate this height adjustment for various configurations. Figure 2 shows a change to a lower height H, with the wire reservoir 7 shown schematically. As shown and explained in Figure 1, a large number of lattice girders 1 with a specific height H are initially produced until the height H needs to be changed. The last lattice girder 1 produced is shown on the right in Figure 2. Once it is determined that the height H needs to be changed, the diagonal chord(s) 4 are no longer welded to the top chord 3 or the bottom chord(s) 2. The bending device 10 is stopped in time to ensure that the last bend for the produced lattice girder 1, shown on the right in Figure 2, is completed.Since the last truss 1 produced is moved forward to the cutting position 5 to be cut with the cutting device 10, the truss 1 remains connected to the wires for the individual chords at its feed-side end 6. The height H can now be adjusted, i.e., lowered. For this purpose, the top chord feed device 12 and the top chord welding device 8 can be lowered and the bending device 10 adjusted in position in one movement. Once this has been done, the truss 1 can be cut at its feed-side end 6 with the cutting device 11. Afterwards, the individual wires for the chords are retracted. For the top chord 3, the free wire end is retracted to the top chord welding device 8, for the bottom chord assembly to the bottom chord welding device 9, and for the diagonal chord(s) 4 at least to a starting point near the bending device 10.Afterwards, the production of lattice girders 1, now with a reduced height, can take place, as indicated by dashed lines for the diagonal chords in Fig. 2 (and analogously in Fig. 3). Despite the retraction of the wires in a reverse direction R, the changeover process is exceptionally fast because the individual components for the top chord 3 can be lowered in a single step. When starting up after the changeover process for a lattice girder 1 with a different height H, the diagonal chords are first conveyed and bent by the bending unit 10 until they can be welded to the top chord. The diagonal chords with the welded top chord are then produced up to the bottom chord welding unit 9, so that the bottom chord can also be welded to the diagonal chords. Afterwards, the wires or chords can be advanced together at the same speed.

[0028] Fig. 3 shows a changeover to a greater height H for the same device from Fig. 1 and Fig. 2 with the same device components. The process is essentially analogous to the process in Fig. 2, except that the height H is increased. Similar to the process shown in Fig. 2, the individual components for the top chord (top chord feed unit 12 and top chord welding unit 8) can be raised in a single movement. Another advantage is that a single cutting unit 11, located at the cutting position 5, can be used both during the ongoing operation of a sequential production of lattice girders 1 of the same height and in an unchanged position when changing the height H. Overall, this results in a structurally simple solution. At the same time, wire waste is essentially avoided due to the retraction of the wires to the starting position described above.Retracting the wire in the reverse direction (R) offers the additional advantage that wire changes can be made relatively easily when different wire diameters are required. In this case, one or more wires are not pulled all the way back to the starting position, but completely retracted onto a spool or coil. New wire can then be threaded on, and work can be carried out with a different wire diameter.

Claims

Patent claims 1. A method for manufacturing lattice girders (1) from wires, wherein the lattice girders (1) comprise chords with a lower chord arrangement having at least one lower chord (2), in particular two lower chords (2), and a top chord (3) which is arranged at a certain height (H) relative to the lower chord arrangement, and at least one, in particular two, diagonal chords (4) running back and forth between the lower chord arrangement and the top chord (3), for example in a zigzag pattern, wherein the wires for the chords are fed in a forward direction (V) and the at least one diagonal chord (4) is welded to the lower chord arrangement and to the top chord (3), wherein the height (H) is changed to manufacture different lattice girders, characterized in that, to change the height (H) between successive lattice girders (1), a manufactured lattice girder (1) is positioned with a feed-side end (6) at a cutting position (5), whereupon the height (H) is changed.whereupon the constructed lattice girder (1) is cut off and the cut wires are pulled in a reverse direction (R) to produce the next lattice girder (1) with the changed height (H).

2. Method according to claim 1, characterized in that the produced lattice girder (1) is moved forward with the feed-side end (6) to the cutting position (5).

3. Method according to claim 1 or 2, characterized in that the cut wires are drawn into a wire reservoir (7).

4. Method according to one of claims 1 to 3, characterized in that the wires are supplied from a wire reservoir (7).

5. Method according to one of claims 1 to 4, characterized in that the cut wire for the top chord is drawn in up to a top chord welding device (8).

6. Method according to one of claims 1 to 5, characterized in that the cut wire(s) for the bottom chord arrangement are drawn in up to a bottom chord welding device (9).

7. Method according to one of claims 1 to 6, characterized in that the cut wire(s) for the diagonal belt (4) are extended to a bending device (10) be confiscated.

8. Method according to one of claims 1 to 7, characterized in that the cut wire(s) for the diagonal chord (4) are bent before welding with the top chord (3) and, when the height (H) is changed, bending of the wire(s) for the diagonal chord (4) is stopped before welding a lattice girder (1).

9. Device for manufacturing lattice girders (1) from wires, wherein the lattice girders (1) comprise chords with a lower chord arrangement having at least one lower chord (2), in particular with two lower chords (2), and a top chord (3) which is arranged at a certain height (H) relative to the lower chord arrangement, and at least one, in particular two, diagonal chords (4) running back and forth between the lower chord arrangement and the top chord (3), for example in a zigzag pattern, in particular for carrying out a method according to one of claims 1 to 8, comprising a wire reservoir (7), at least one transport device for feeding the wires for the chords from the wire reservoir (7) in a forward direction (V), at least one bending device (10) for bending the wire(s) for the diagonal chord (4),at least one lower chord welding device (9) for welding the diagonal chord (4) to the lower chord assembly and at least one upper chord welding device (8) for welding the diagonal chord (4) to the upper chord (3) and a cutting device, (11) for cutting to length a constructed lattice girder (1), characterized in that the device has an adjustment device for adjusting the height (H) before cutting to length the constructed lattice girder (1).

10. Device according to claim 9, characterized in that the wire reservoir (7) is configured to draw in wires in a reverse direction (R).

11. Device according to claim 9 or 10, characterized in that a feed device is provided with which the produced lattice girder (1) can be moved forward with the feed-side end (6) to a cutting position (5).

12. Device according to one of claims 9 to 11, characterized in that a drawing and control unit is provided with which cut wire for the top belt can be drawn in up to the top belt welding device (8) and positioned with a free wire end on it.

13. Device according to one of claims 9 to 12, characterized in that a drawing and control unit is provided with which cut wire for the lower belt arrangement can be drawn in up to the lower belt welding device (9) and positioned with a free wire end on it.

14. Device according to one of claims 9 to 13, characterized in that a drawing and control unit is provided with which cut wire for the diagonal belt arrangement can be drawn in up to the bending device (10) and positioned with a free wire end on it.

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