EP0707907A1 - Method for the production of mesh panels - Google Patents

Abstract

Long wires (3.1-3.8) are fed from spools (2.1-2.8) in a welding machine (12) along a corresponding number of paths, and are welded into a strip via transverse wires (16.1-16.4). Mat sections of the desired lengths are then parted off from the continuous strip so formed. Two or more spools are provided for each path. The changeover between the wire from an exhausted spool and that from the fresh one is carried out by parting off the former before the machine at the point where a complete mat section is to be parted off after it. Between the spools and the machine, the lengthwise wires can be passed through a buffer zone (7.1,7.8), whose capacity is at least equal to a mat-section length.

Description

Technical field

The invention relates to a method for producing lattice mats, in which longitudinal wires are fed from wire spools to a lattice welding machine with n longitudinal wire paths, are welded by the latter to a lattice belt by transverse wires and are then cut off along a cutting line corresponding to a desired mat length for producing the lattice mats.

The invention further relates to a plant for carrying out the method.

State of the art

Processes and plants for the production of wire mesh mats, in particular structural steel mats, with longitudinal wire feed from wire spools are generally known (cf., for example, brochure "Schlatter, PG-System", No. 4.103D, 4.1984).

A problem with the known systems is that the entire system has to be switched off in order to replace a wire coil. This means an undesirable loss of efficiency, which is particularly important in high-performance systems.

Presentation of the invention

The object of the invention is to provide a method of the type mentioned at the outset which eliminates or at least significantly reduces the downtimes mentioned without impairing the quality of the mesh mats produced.

According to the invention, a method of the type mentioned is characterized in that at least two wire coils are provided per longitudinal wire path and in that the change from a first, empty wire coil to a second, full wire coil is determined by deliberately severing the longitudinal wire fed to the mesh welding machine on the input side of the mesh welding machine is that a transition between the cut longitudinal wire of the first wire coil and the inserted longitudinal wire of the second wire coil on the output side of the grid welding machine coincides with the cutting line for severing the desired mat length.

The main idea is that the transition from one wire spool to the other is defined in such a way that the (not welded) transition between the "old" wire and the "new" wire is laid in such a way that it is to be cut with the cut side that is to be made anyway on the output side of the mesh welding machine coincides. Within a finished mesh mat, there are neither double guided nor interrupted longitudinal wires.

, wobei m = Anzahl Querdrähte pro Gittermatte und d = Querdrahtabstand.)A buffer zone for the longitudinal wires is preferably provided between the wire coils and the grid welding machine. The buffer capacity of this zone corresponds to at least about one mat length. This allows the end of the wire (the empty wire spool) for the subsequent welding of the new wire start to be clamped on the input side of the buffer zone and to supply the wire-mesh welding machine with wire from the buffer zone until the time for cutting the "old" and inserting the "new" longitudinal wire is there . It is clear that with a buffer capacity of one mat length there is always enough reserve. (Strictly speaking, a somewhat smaller buffer capacity of $\text{(m-1) * d}$

, where m = number of cross wires per grid mat and d = cross wire spacing.)

There is always a piece of wire in the buffer zone, which is welded onto the "new" wire as a leader. The switchover from one line wire to the other on the input side of the grid welding machine can be carried out very quickly. It is sufficient to cut the currently fed line wire and to add the one in the waiting position. In principle, there is enough time to replace the empty (first) wire spool with a new (third) until the full (second) wire spool is empty.

The system knows the length of the mesh belt at all times in order to be able to initiate the process of cutting off a mesh mat in good time. As a result, it can also be calculated when or where a fed line wire has to be cut on the input side of the mesh welding machine so that the separation point coincides with a mat end. The interface is located at a point whose distance from the end of the grid corresponds to an integral multiple of a mat length. If the mat length varies, the so-called mat grid can be assumed in a general manner.

A system for carrying out the method comprises a grid welding machine with n line wire paths, a line wire feed system with exchangeable wire coils and a (first) cutting device arranged on the output side of the grid welding machine for cutting the line wires according to the desired mat length. According to the invention, the line wire feed system is designed for two wire coils per line wire. On the input side of the grid welding machine, a wire changing system is provided with a switch per line wire and a (second) cutting device for cutting through a selected line wire. The wire changing system is controlled in such a way that the selected longitudinal wire is cut at a point that coincides with a selected mat length grid.

The system according to the invention can basically be assembled from components known per se. A significant difference to the known systems, however, lies in the control and monitoring (typically implemented in software).

The cutting device of the wire changing system preferably has a controlled crosswise to the longitudinal wire cores movable scissors. The scissors are positioned on the wire that will end next. As soon as the pre-calculated point of the line wire to be cut comes, the scissors are actuated. Instead of a single pair of scissors, several scissors, in particular one for each line wire, can also be provided.

A buffer zone can be realized by providing a storage space for each longitudinal wire to accommodate one (or more) wire loop (s). The so-called fill level of the storage space can be determined with sensors. The wire drives provided on the input side of the buffer zone are corresponding to the fill level or. the required replenishment speed. The input wire drives mentioned preferably work continuously. A particularly simple embodiment results, for. B. if two wire drives with slightly different speeds are provided one behind the other. Depending on whether the replenishment speed should be higher or lower, the faster or the slower wire drive is used on the line wire.

The decision as to which of the wire coils will be empty next can be made by the operating personnel or on the basis of an automatic control. In the latter case, sensors for monitoring the wire coils are to be provided. These detect e.g. B. optically or via a weight measurement, which of the coils is next empty. A line wire change can then be prepared on the basis of the sensor signals (positioning of the scissors, etc.).

A synchronous drive for the gradual advancement of the longitudinal wires is preferably arranged on the input side of the grid welding machine and in front of the wire changing system. He pushes the longitudinal wires to be welded into the grid welding machine. The waiting wires are not in contact with the drive. If a change is made from one line wire to the other, the severed line wire is released from engagement with the drive and the new line wire is pushed.

The synchronous drive has z. B. a transport roller extending over an entire width of the system and an individually lifting or lowering pinch roller for each line wire. By lowering the pinch roller, the corresponding line wire is brought into engagement with the transport roller. So that the line wire does not drag on the drive roller when the pinch roller is lifted, means can be provided to lift the corresponding line wire from the transport roller.

A sensor or switch for detecting the end of the longitudinal wire and a clamping device for holding the end are provided in the vicinity of each interchangeably mounted wire coil. The longitudinal wire end is held until the beginning of a new, full wire spool is welded on.

It is known to arrange two conventional lattice welding machines head to head and to operate them synchronously in order to increase the processing speed. In this way, two cross wires are welded one after the other per welding cycle. The feed per welding cycle then corresponds to twice the mesh size of the mesh. In such welding systems operating with a double stroke, the cutting devices are preferably longitudinally displaceable (namely by half a stroke), around both mesh mats with an even number of transverse wires and with an odd number To be able to produce number of cross wires. Instead of making the cutting devices displaceable in the longitudinal wire direction, drives with half-step feeds can also be provided.

Further advantageous combinations of features result from the detailed description and the entirety of the claims.

Brief description of the drawings

Fig. 1

Eine schematische Darstellung einer erfindungsgemässen Anlage;

Fig. 2

eine schematische Darstellung einer bevorzugten Vorrichtung zum selektiven Schneiden von Längsdrähten;

Fig. 3a, b

eine Vorrichtung zum selektiven Antreiben der Längsdrähte eingangsseitig der Gitterschweissmaschine.

The drawings used to explain the exemplary embodiments show:

Fig. 1

A schematic representation of a system according to the invention;

Fig. 2

a schematic representation of a preferred device for selective cutting of longitudinal wires;

3a, b

a device for selectively driving the longitudinal wires on the input side of the grid welding machine.

Ways of Carrying Out the Invention

Fig. 1 shows schematically a frame 1 with z. B. eight coils 2.1, ..., 2.8. (In the practical version, the number of coils will generally be considerably larger, for example 10 to 40.) The coils 2.1, ..., 2.8 are easily replaceable. The wires wound on them are called Line wires 3.1, ..., 3.8 used to manufacture the mesh.

In the present example, the coils 2.1, ..., 2.8 are arranged one behind the other in two rows of four. Each of the coils 2.1, ..., 2.8 is assigned a clamping unit 4.1, ..., 4.8, which (e.g. with a contact switch) can detect the end of the line wire and clamp it immediately.

The longitudinal wires 3.1, ..., 3.8 are aligned in eight wire straightening devices 5.1, ..., 5.8. The eight wire straightening devices 5.1, ..., 5.8 are devices of a known type.

Behind the wire straightening devices 5.1, ..., 5.8 follow individually controllable drives 6.1, ..., 6.8. They continuously pull the longitudinal wires 3.1, ..., 3.8. Its drive speed is preferably adjustable. At least two speed levels should be available. The meaning of the adjustable speed is explained below.

Next are eight buffers 7.1, ..., 7.8. You will e.g. B. formed by a box divided into a variety of high, narrow and long compartments. A wire loop can be placed in each compartment. The intermediate stores 7.1, ..., 7.8 form a buffer zone between the wire feed system (frame 1 with coils 2.1, ..., 2.8) and the downstream grid welding machine 12.

After the intermediate stores 7.1, ..., 7.8, wire straightening devices 8.1, ..., 8.8 can be provided again in order to improve or correct the longitudinal wire alignment.

Next is a step drive 9 for synchronously advancing four of the eight longitudinal wires 3.1, ..., 3.8. In the present example, the longitudinal wires 3.2, 3.4, 3.5 and 3.8 are conveyed. The other longitudinal wires 3.1, 3.3, 3.6, 3.7 are not in engagement with the stepping drive 9 and therefore stand still.

Immediately behind the stepping drive 9 is a wire cutter 10 with which longitudinal wires can be selectively cut.

In the present example, a wire mesh 14 with four longitudinal wire wires 15.1, ..., 15.4 is produced with a wire mesh welding machine 12. Of the eight longitudinal wires 3.1, ..., 3.8, only every second one is processed. Of the longitudinal wires 3.1 / 3.2, 3.3 / 3.4, 3.5 / 3.6, 3.7 / 3.8, which belong together in pairs, one is fed to the grid welding machine 12 via a switch device 11.1, ..., 11.4. This welds the mentioned longitudinal wires in a manner known per se with transverse wires 16.1, ..., 16.4.

The switch devices 11.1, ..., 11.4 are z. B. formed by funnel-shaped conductive guide elements. They bring the longitudinal wires 3.2, 3.4, 3.5, 3.8 to be welded onto the longitudinal wire paths of the lattice welding machine 12.

A longitudinal wire cutter 13 known per se is arranged on the output side of the grid welding machine 12. It separates mesh mats of a desired mesh length from the (four-wire) mesh belt supplied by the mesh welding machine 12.

The operation of the system will now be described in detail below.

For the sake of simplicity, it is assumed that all eight coils 2.1, ..., 2.8 are more or less full. 1, the four longitudinal wires 3.2, 3.4, 3.5, 3.8 are continuously unwound from the corresponding coils with the aid of the drives 6.2, 6.4, 6.5, 6.8 and pushed into the corresponding intermediate stores 7.2, 7.4, 7.5, 7.8. From there they are inserted into the grid welding machine 12 by the stepping drive 9 with a stroke which is predetermined by the mesh size (i.e. the spacing of the cross wires) via the switch devices 11.1, ..., 11.4. The four longitudinal wires 3.2, 3.4, 3.5, 3.8 are welded with cross wires in the grid welding machine 12. At regular intervals (corresponding to the desired mat length), the line wire cutters 13 cut through the line wires mentioned.

If one of the four active coils 2.2, 2.4, 2.5, 2.8 threatens to become empty, this will e.g. B. entered by the operating personnel at a control panel of the system. For the following explanations it is assumed that the coil 2.2 will be empty next.

First, e.g. B. the wire cutter 10 is positioned at the corresponding line wire 3.2. The clamping unit 4.2 monitors the line wire 3.2 and clamps it as soon as it detects the end of the wire.

From the end of the wire mesh or wire mesh 14, the position of which is known to the system-internal control at any time due to monitoring, it is now calculated back when the desired interface of the longitudinal wire 3.2 arrives at the wire cutter 10. The interface searched has a distance from the end of the wire mesh 14 (and thus from the front end of the longitudinal wire 3.2), which corresponds to an integral multiple of the mat length to be produced. From The wire locations defined by this criterion are only of interest to those who are immediately in front of the wire cutter 10. which comes next to the wire cutter 10. It is obvious that the distance of the line wire sought from the wire cutter must be less than a mat length. In one extreme case, the interface sought is precisely the case with the wire cutter 10 when the clamping unit 4.2 detects the end of the longitudinal wire 3.2. In the other extreme case, the interface sought is at a distance which corresponds to the mat length reduced by a cross-wire subdivision.

Since the longitudinal wires 3.2, 3.4, 3.5, 3.8 are advanced by the stepping drive 9 by one cross wire pitch (= stroke), the distance of the sought location from the wire cutter 10 can be quantified by a number of steps. On the basis of the current position of the wire grating 14, the system controller thus determines the number of steps that have to be carried out until the desired interface of the longitudinal wire 3.2 has reached the wire cutter 10.

So while the clamping unit 4.2 now holds the line wire 3.2 at its rear end, the stepping drive 9 processes the required number of steps, the line wire 3.2 still being fed to the grid welding machine 12 using the buffer capacity of the buffer store 7.2.

If the desired, pre-calculated interface is located at the wire cutter 10, the line wire 3.2 is released from engagement with the stepper drive 9, clamped by clamping jaws and severed by the wire cutter. In return, the line wire 3.1 is brought into engagement with the stepper drive 9.

With the next stroke of the stepper drive 9, the longitudinal wires 3.1, 3.4, 3.5, 3.8 are now pushed. The line wire 15.1, which is formed by a cut off, front piece of the line wire 3.2, is of course drawn in synchronism with the line wires 3.1, 3.4, 3.5, 3.8 in the grid welding machine 12, since they have cross wires 16.1, ..., 16.4 with the Longitudinal wires 3.4, 3.5, 3.8 is connected. Immediately afterwards, but not overlapping, the line wire 3.1 is inserted into the grid welding machine 12 with the help of the switch device 11.1.

On the output side of the grid welding machine 12, the line wire 15.1 shows an interruption at a later point in time. However, since an entire mat length is always cut off from the mesh belt, and the interruption has been correctly calculated in advance, it coincides with an already required cutting line for severing a finished mesh mat. The transition from the line wire 3.2 of the one coil 2.2 to the line wire 3.1 of the other coil 2.1 does not appear at all in the finished grid mats.

The operating personnel now have time to replace the empty coil 2.2 with a full one and to weld the wire start of the full coil to the wire end held in the clamping unit 4.2. When this work is done, the drive 6.2 can be actuated in order to feed enough line wire into the buffer 7.2 so that its full buffer capacity is restored. (Before cutting the longitudinal wire 3.2, a certain length of this wire was subtracted from the buffer 7.2.)

The level of each buffer is z. B. monitored by sensors. If it is too small, the conveying speed of the corresponding drive 6.1, ..., 6.8 is increased. However, if the buffer 7.1, ..., 7.8 is full, the replenishment speed is reduced. According to a preferred embodiment, the retraction speed can be switched back and forth between a slightly higher and a slightly lower conveying speed (with respect to an average conveying speed of the stepping drive 9).

Preferred embodiments and variants for the individual system elements are to be explained below.

A specific embodiment of the wire cutter 10 will be explained by way of example with reference to FIG. 2. A bracket 18 is slidably mounted on a horizontal guide rail 17 which is transverse to the longitudinal wires 21.1, ..., 21.5. A drive, not shown, can move the bracket 18 along the guide rail 17 (in the direction of movement 22) and according to a control signal from the system control under a selected longitudinal wire z. B. Position 21.3.

A scissor head 19 is seated on the holder 18 and can be raised or lowered in the direction of movement 23 (perpendicular to the direction of movement 22 and to the longitudinal wires 21.1, ..., 21.4). In Fig. 2 the scissor head 19 is shown in the lowered position. To cut it, it is raised (by a drive mechanism, not shown in detail) in such a way that the selected longitudinal wire 21.3 comes to lie between the scissor arms 20.1, 20.2 of the scissor head 19 and can be cut by a scissor movement.

As part of the working method already described, the scissor head 19 is used to initiate a line wire change under the one to be cut (because it is coming to an end). Line wire 21.3 positioned. As soon as the end of the corresponding line wire is unwound from the empty spool and has been detected and held by the feed system and as soon as the pre-calculated separation point of the line wire has reached the wire cutter, the cutter head shoots up, performs the cut and is lowered again. Now the scissor head 19 can be controlled for the change of line wire of another pair of line wires.

3a, b shows a possible embodiment of the stepping drive 9 from the front and from the side. A roller 24, which extends over the entire width of the installation, is driven by a stepping drive 25 in accordance with the mesh size (spacing of the transverse wires). A roller 26.1, ..., 26.8 is provided for each line wire 27.1, ..., 27.8 in order to press the line wires 27.1, 27.3, 27.6, 27.7 to be advanced onto the roller 24. The rollers 26.1, ..., 26.8 can be raised. The mechanism for lifting and lowering the rollers 26.1, ..., 26.8 is not shown in detail and can, for. B. as explained in EP-0 073 336. On the output side of the roller 24, a clamping mechanism (not shown) with clamping jaws 28.11 / 28.12, ..., 28.81 / 28.82 is provided for each longitudinal wire 27.1, ..., 27.8. With the clamping jaws 28.21 / 28.22, 28.41 / 28.42, 28.51 / 28.52, 28.81 / 28.82 the waiting wires 27.2, 27.4, 27.5, 27.8 are held in such a way that they are lifted off the roller 24.

Z. B. the longitudinal wire 27.1 to the end, it is clamped with the clamping jaws 28.11 / 28.12 (at the same time the roller 26.1 is released) and severed by the wire cutters according to FIG. 2. The associated line wire 27.2 is released from the clamping jaws 28.21 / 28.22 by lowering the roll 26.2 pressed onto the roller 24 and advanced during the next stroke movement instead of the longitudinal wire 27.1.

As a grid welding machine 12, a so-called tandem welding system can also be used, as is the case, for. B. is described in DE-42 07 672. The stroke of the stepper drive must then be twice the mesh size. To ensure that not only mesh mats with even-numbered, but also with odd-numbered cross-wire divisions can be manufactured, z. B. the following measures are possible: longitudinal displaceability of the wire cutter 10 and the longitudinal wire cutter 13 or half and full stroke steps of the stepping drive 9 (corresponding to the single or double mesh size).

If it is foreseeable that two bobbins will be empty at the same time, a change can be forced prematurely for one line wire. This prevents the wire cutter 10 from having to make the cut at the same time on two longitudinal wires. This would lead to a temporary plant shutdown. If a separate pair of scissors is provided for each line wire instead of a single pair of scissors that can be moved transversely to the longitudinal wires, the simultaneous replacement does not pose any problems.

In summary, it can be stated that the invention has created an extremely simple and elegant solution for the essentially standstill-free changing of the longitudinal wires.

Claims (15)

Method for producing lattice mats, in which longitudinal wires (3.1, ..., 3.8) a) fed from wire coils (2.1, ..., 2.8) to a mesh welding machine (12) with n longitudinal wire paths, b) welded by this by cross wires (16.1, ..., 16.4) to a grid band and c) are then cut off along a cutting line corresponding to a desired mat length in order to produce the grid mats, characterized in that d) at least two wire coils (2.1 / 2.2, 2.3 / 2.4, 2.5 / 2.6, 2.7 / 2.8) are provided per line wire path and e) that the change from a first, empty wire spool (2.2) to a second, full wire spool (2.1) by deliberately severing the longitudinal wire (3.2) fed to the mesh welding machine (12) is determined on the input side of the mesh welding machine (12) such that a transition between the cut longitudinal wire (3.2) of the first wire coil (2.2) and the inserted longitudinal wire (3.1) of the second wire coil (2.1) on the output side of the grid welding machine (12) coincides with the cutting line for severing the desired mat length. Method according to claim 1, characterized in that the longitudinal wires (3.1, ..., 3.8) between the wire coils (2.1, ..., 2.8) and the grid welding machine (12) through a buffer zone (7.1, ..., 7.8) with a buffer capacity of at least about one mat length. Method according to Claim 2, characterized in that one end of the longitudinal wire (3.2) of the empty wire coil (2.2) is detected and held (4.2) on the input side of the buffer zone (7.2) in order to weld it onto a wire start instead of the first wire coil (2.2) third full wire coil used. Method according to one of claims 1 to 3, characterized in that the supplied longitudinal wire (3.2) is severed at a distance corresponding to an integral multiple of the desired mat length from a current end of the mesh belt. Plant for carrying out the method according to claim 1, comprising a) a grid welding machine (12) with n parallel longitudinal wire paths, b) a line wire feed system (1, 2.1, ..., 2.8) with interchangeable wire spools (2.1, ..., 2.8) and c) a first cutting device (13) for cutting arranged on the output side of the grid welding machine (12) the longitudinal wires (3.1, ..., 3.8) according to a desired mat length, characterized in that d) the line wire feed system (1, 2.1, ..., 2.8) is designed for two wire spools (2.1 / 2.2, 2.3 / 2.4, 2.5 / 2.6, 2.7 / 2.8) per line wire path and that e) on the input side of the mesh welding machine (12), a wire changing system (10, 11.1, ..., 11.4) comprising a switch (11.1, ..., 11.4) per line wire path and a second cutting device (10) for cutting through a selected line wire (e.g. B. 3.2) is provided, which is controlled such that the selected longitudinal wire (3.2) is cut at a distance corresponding to a certain mat length grid from a current end of the mesh belt. System according to claim 5, characterized in that the cutting device (10) of the wire changing system (10, 11.1, ..., 11.4) has a shear (19, 20.1, 20.2.) Which can be moved transversely to the longitudinal wires (3.1, ..., 3.8) ) having. System according to one of claims 5 or 6, characterized in that a buffer zone with separate storage spaces (7.1, ..., 7.8) for receiving at least one wire loop for each longitudinal wire (3.1, ..., 3.8) of the feed system (1, 2.1, ..., 2.8) is provided. Installation according to claim 7, characterized in that continuously pulling wire drives (6.1, ..., 6.8) are provided on the input side of the buffer zone. System according to claim 8, characterized in that the wire drives (6.1, ..., 6.8) have several, in particular two, discrete speed stages in order to feed the longitudinal wires (3.1, ..., 3.8) into the buffer zone in accordance with a feed speed currently required can. System according to one of claims 5 to 9, characterized in that a synchronous drive (9) for the gradual, simultaneous advancement of the processed longitudinal wires (3.2, 3.4, 3.5, 3.8) is arranged in front of the second cutting device (10) and that optionally one per longitudinal wire path Line wire (3.2, 3.4, 3.5, 3.8) can be transported. System according to claim 10, characterized in that the synchronous drive (9) has a transport roller (24) extending over an entire system width and for each longitudinal wire (27.1, ..., 27.8) an individually lifting or lowering clamping roller (26.1,. .., 26.8). Installation according to claim 11, characterized in that means (28.11 / 28.12, ..., 28.81 / 28.82) are provided for the corresponding longitudinal wire (27.2, 27.4, 27.5, 27.8) with the pinch roller (26.2, 26.4, 26.5, 26.8 ) from the transport roller (24). System according to one of claims 5 to 12, characterized in that the grid welding machine (12) welds two transverse wires (16.1, ..., 16.4) per cycle interval and that the first and second cutting devices (13 and 10) are displaceable in the direction of the longitudinal wire paths are. System according to one of claims 7 to 13, characterized in that sensors are provided for monitoring a filling level of the storage spaces (7.1, ..., 7.8). System according to one of claims 5 to 14, characterized in that sensors are provided to detect whether a coil (2.1, ..., 2.8) is empty or is empty in a predetermined time interval.

Images