ZA200209685B

ZA200209685B - Multispot welding machine for producing wire mesh mats.

Info

Publication number: ZA200209685B
Application number: ZA200209685A
Authority: ZA
Inventors: Klaus Ritter
Original assignee: Evg Entwicklung Verwert Ges
Priority date: 2001-03-07
Filing date: 2002-11-28
Publication date: 2004-02-12
Also published as: EP1368145A1; WO2002070168A1; EP1368145B1; DE50200963D1; ATA3562001A; AT409941B

Description

000027 9a § ® 1 PCT/AT02/00035

Multispot Welding Machine for Producing Wire Mesh Mats

The invention relates to a multispot welding machine operating according to the electrical resistance method, for producing wire mesh mats from a sheaf of parallel longitudinal wires and cross-wires crossing the former at a right angle, which are arranged above and underneath the longitudinal wires opposite one another and are welded to the longitudinal wires, with a cross-wire channel each arranged above and underneath a horizontal longitudinal wire feeding plane on the outlet side of the finished welded wire mesh mat, with cross-wire feeders that feed the cross-wires from the cross-wire channels into the welding plane between the sheaf of longitudinal wires and rows of top welding electrodes and bottom welding electrodes, that can be raised and lowered, arranged on either side thereof, and with a current bridge each for the top electrodes passing through the longitudinal wire feeding plane.

A mesh welding machine of this type is known from the AT - 398 920. With this machine the cross-wire feeders are arranged on the outlet side of the finished welded wire mesh mat and additional cross-wire stops are arranged on the inlet side of the longitudinal wires. The top cross-wires are moved into the welding position by the effect of gravity, whereas the bottom cross-wires are lifted by fork- shaped feeder elements along a specific feeder path into the welding position. This machine has the disadvantage that the cross-wire feeders are arranged on the outlet side of the wire mesh mat and the wire mesh mat can, therefore, after the welding only be moved on when the feeder elements have completely freed the movement path of the welded-on cross-wires, as a result of which the next welding cycle can only take place correspondingly later. To be able to produce wire mesh mats with small cross-wire spacing, the feeder elements must be moved extremely far out of the welding plane, due to which the time between the welding operations is also prolonged accordingly. Furthermore the top cross-wires are moved into the welding plane only under the effect of gravity, so that the feeding speed of these cross-wires is relatively slow. Moreover, additional cross-wire stops

530027 8:85 ® 2 PCT/AT02/00035 are required in the welding plane, which must also be moved when changing the longitudinal wire spacing.

It is the object of the invention to avoid the described disadvantages and to provide a machine of the type mentioned at the outset, which makes it possible to economically produce a wire mesh mat at a high production speed, wherein an extremely small cross-wire spacing and in addition a quick and technically simple changing of the longitudinal wire spacing in the wire mesh mat should be possible.

The machine according to the invention has the characteristics that a cross-wire channel each above and underneath the longitudinal wire feeding plane is arranged, seen in the production direction, on the inlet side of the sheaf of longitudinal wires in front of the welding plane defined by the top and bottom electrodes, that every cross-wire feeder comprises a simultaneously swivelable and advanceable feeder arm and that the two feeder arms in a synchronous feeding movement simul- taneously move the cross-wires from the cross-wire channels into the welding plane, wherein the top cross-wire is placed on the longitudinal wires and the bottom cross-wire on the bottom electrodes.

A preferred embodiment of the invention is characterised in that the feeder arms execute a simultaneous advancing and tilting movement, wherein a movement device is provided which is controlled by an advancing cam and a tilting cam, which are arranged in a fixed relation in a non-turning manner on a common, continuously driven drive shaft.

According to a further characteristic of the invention, the advancing cam and the tilting cam are designed in such a way that after placing the cross-wires in their welding positions in the welding plane, notwithstanding a continued driving of the drive shaft, the feeder arms stand still until the cross-wires are securely clamped between the longitudinal wires and the top and bottom electrodes.

Preferably, the turning movement of the drive shaft for the advancing cam and tilting cam is adapted to the movements for feeding the cross-wires into the

® . 3 PCT/AT02/00035 cross-wire channels and with the advancing movements of the longitudinal wires and the wire mesh mat with the aid of a central control unit.

According to a further development of the invention it is provided that, in order to change the longitudinal wire spacing, the top electrodes are arranged in a top welding head that can be moved horizontally in the welding plane and the bottom electrodes in a bottom welding head that can be moved horizontally in the welding plane, wherein the top welding head and the bottom welding head are connected by two side plates, and the feeder arms, each with the aid of a clamp fastener, are arranged in such a way that they can be moved horizontally parallel to the welding plane and be fixed on their feeder bar.

Further characteristics and advantages of the invention will be explained in more detail in the following with reference to exemplified embodiments illustrated in the drawings, wherein: Fig. 1 is a side view of an exemplified embodiment of a machine according to the invention with stationary welding unit, Fig. 2 a side view of another exemplified embodiment of the machine according to the invention with an infinitely adjustable welding unit, Fig. 3a is a diagrammatic side view of the movement devices of the cross-wire feeder arms for the exemplified embodiments according to Fig. 1 and 2, and Fig. 3 b shows the feeder paths of the two cross- wires.

The devices illustrated in Fig. 1 to 3 are used in a resistance mesh-welding machine for producing wire mesh mats G from steel wire, which consist of longitudinal wires L, and top cross-wires Q1 and bottom cross-wires Q2 that cross the longitudinal wires L at a right angle. With this machine several longitudinal wires L are fed parallel and together, at a lateral distance from one another, i.e. with a preset longitudinal wire spacing, along the horizontally extending longi- tudinal wire feeding plane E-E in the arrow direction P1. The top cross-wires Q1 are placed at a right angle to the longitudinal wires L on the latter in the vertical welding plane S-S that extends at a right angle to the longitudinal wire feeding plane E-E, whereas the bottom cross-wires Q2 are placed, at a right angle to the

® . 4 PCT/AT02/00035 lohgitudinal wires, underneath the longitudinal wires, simultaneously with the top cross-wires Q1, in the welding plane S-S. The cross-wires Q1, Q2 are welded jointly and simultaneously at the crossing points to all longitudinal wires L. The surface of the wires L, Q1, Q2 can be smooth or, as is common with reinforcing steel, ribbed.

The device illustrated in Fig. 1 comprises per longitudinal wire L a stationary welding unit 1, which serves for producing wire mesh mats G with a fixed, unchangeable longitudinal wire spacing. The welding unit 1 has a stationary top welding head 3 arranged above the longitudinal wire feeding plane E-E, and a stationary bottom welding head 4 arranged underneath the longitudinal wire feeding plane E-E. The top welding head 3 has a top electrode holder 5 that can be raised and lowered in the directions of the double arrow P2, and the bottom welding head 4 has a stationary bottom electrode holder 6. Within the framework of the invention it is also possible, however, to also make the bottom electrode holder 6 such that it can be raised and lowered. At the bottom end of the top electrode holder 5 a top electrode 7 is arranged, and at the top end of the bottom electrode holder 6 a bottom electrode 8. The top electrode 7 and the bottom electrode 8 have the shape of a circular disc and are screwed to their electrode holders 5, 6 by screw connections 9 and 9’ respectively. The top and bottom electrodes 7’, 8° can, as illustrated in Fig. 2, be disk-shaped in the form of a polygon, e.g. an octagon or dodecagon. Within the framework of the invention these top and bottom electrodes 7°, 8’ can comprise at their periphery a cross-wire groove at every polygon face, which serves to hold the cross-wires Q1 and Q2 respectively during the welding, and which is V-shaped and is adapted to the dimensions of the cross-wire Q.

The power supply of all bottom electrode holders 6 takes place via a front bus bar 10, which is connected to the front connection 11 of a welding transformer or the front connections of several welding transformers. The power supply of all top electrode holders 5 takes place via a rear bus bar 12, which is connected to the rear connection 13 of a welding transformer or the rear

® 5 PCT/AT02/00035 connections of several welding transformers. The power connection to the top electrode holder 5 takes place with the aid of a current bridge 14, which seen in the production direction P1 is arranged on the inlet side of the longitudinal wire sheaf L in front of the welding plane S-S, passes through the longitudinal wire feeding plane E-E and in the area of the longitudinal wires L has suitable through- openings for these. The current bridge 14 is connected to the top movable electrode holder 5 by a flexible current lead 15. The one half of the welding circuit of the welding unit 1 is formed by the front bus bar 10, the bottom electrode holder 6 and the bottom electrode 8, whereas the other half of the circuit is formed by the rear bus bar 12, the current bridge 14, the current lead 15, the top electrode holder 5 and the top electrode 7. The rear bus bar 12 and the current bridge 14 are fastened to the front bus bar 10 and the bottom electrode holder 6 respectively, electrically separated by an insulating layer 16 indicated by hatching.

The device has a crosshead 17 extending over the entire width of the welding machine, which with the aid of lateral electrode bar cheeks 18 is fastened to a machine frame - not illustrated - of the welding machine. Every top electrode holder 5 is fastened to an electrode push rod 19, which is mounted in the crosshead 17 and can be moved in the directions of the double arrow P2. The movement in the direction of the longitudinal wire feeding plane E-E is produced by a hydraulically actuated working cylinder, while the electrode push rod 19 is moved in the opposite direction into its starting position by a return spring 20.

The longitudinal wires L are pushed ahead in the arrow direction P1, during which they are guided by a top and bottom longitudinal wire guide 21 and 21’ respectively exactly in the longitudinal wire feeding plane E-E. The longitudinal wire guides 21, 21’ are spring-mounted, so that during the welding of the cross-wires

Q1, Q2 to the longitudinal wires L they can move slightly downwards and if need be upwards. The top cross-wire Q1 is moved with the aid of several top cross-wire feeder arms 22 and the bottom cross-wire Q2 with the aid of several bottom cross- wire feeder arms 22’ from a top cross-wire channel 23 and bottom cross-wire channel 23’ respectively into the welding plane S-S. Every welding unit 1 is

® 6 PCT/AT02/00035 associated with a feeder arm 22 and 22’. The top cross-wire channel 23, which seen in the production direction P1 is arranged on the inlet side of the longitudinal wire sheaf L above the longitudinal wire feeding plane E-E and between the current bridge 14 and the welding plane S-S, i.e. inside the power circuit, and extends over the entire width of the welding machine, is closed off at the bottom by several cross-wire flaps 24, which are mounted in an upper flap shaft 25, swivelable in the directions of the double arrow P3. The bottom cross-wire channel 23’, which seen in the production direction P1 is arranged on the inlet side of the longitudinal wire sheaf L underneath the longitudinal wire feeding plane E-E and between the current bridge 14 and the welding plane S-S, i.e. inside the power circuit, and also extends over the entire width of the welding machine, is in a corresponding manner closed off at the top by several cross-wire flaps 24’, which are mounted in a bottom flap shaft 25’, swivelable in the directions of the double arrow P3’. Every top and bottom cross-wire feeder arm 22, 22’ has at its front end a fork 26 with a V- shaped opening (Fig. 3b), wherein the bottom of the fork opening serves to accommodate the respective cross-wire Q1, Q2. The bottom of the fork opening, in order to feed the top cross-wire Q1, describes a movement path P4 from the starting position A via the cross-wire channel 23 to the welding position Q1’ in the welding plane S-S and back, and in order to feed the bottom cross-wire Q2 it describes a movement path P5 from the starting position A’ via the cross-wire channel 23’ to the welding position Q2’ in the welding plane S-S and back. During these feeding movements the top cross-wire Q1 is additionally guided by a top cross-wire guide 27 and the bottom cross-wire Q2 by a bottom cross-wire guide 27'. The exact course of the movement paths P4, P5, as well as the movement devices for producing these movement paths P4, P5, are described in more detail in Fig. 3a and 3b.

The exemplified embodiment of the device illustrated in Fig. 2 serves to produce wire mesh mats G with changeable longitudinal wire spacings per wire mesh mat G and comprises per longitudinal wire L a horizontally movable welding unit 2. The welding unit 2 consists of a top welding head 3’ arranged above the longitudinal wire feeding plane E-E and a bottom welding head 4’ arranged

® 7 PCT/AT02/00035 underneath the longitudinal wire feeding plane E-E, which can be moved jointly transversely to the longitudinal wire direction P1 horizontally in the longitudinal wire feeding plane E-E and can be fixed in position for the welding. The top welding head 3’ has a top electrode holder 5’ that can be raised and lowered in the directions of the double arrow P2, and the bottom welding head 4’ has a stationary bottom electrode holder 6’. Within the framework of the invention it is also possible, however, to also make the bottom electrode holder 6’ such that it can be raised and lowered. At the bottom end of the top electrode holder 5’ a top electrode 7’ is arranged, and at the top end of the bottom electrode holder 6’ a bottom electrode 8’. The top electrode 7’ and the bottom electrode 8’ have the shape of a polygon, e.g. an octagon or dodecagon, and are screwed to their electrode holders 5’, 6’ by screw connections 9 and 9’ respectively. Within the framework of the invention these top and bottom electrodes 7’, 8’ can comprise at their periphery a cross-wire groove on every polygon face, which serves to hold the cross-wires Q1 and Q2 respectively during the welding, and which is V-shaped and is adapted to the dimensions of the cross-wire Q. Within the framework of the invention, the top and bottom electrodes 7, 8 can have the shape of a circular disc, as illustrated in Fig. 1.

Every top electrode holder 5’ is fastened to an electrode push rod 19, which is mounted in a push-rod frame 28 and can be moved in the directions of the double arrow P2. The movement in the direction of the longitudinal wire feeding plane E-E is produced by a hydraulically actuated working cylinder, while the electrode push rod 19 is lifted in the opposite direction into its starting position by a return spring 20. Over the entire operating width of the welding machine there extends a stationary electrode bar 29, on which the push rod frames 28 of the top electrode holders 5’ are arranged in such a way that they can be moved horizontally transversely to the longitudinal wire direction P1 and can be fixed in place in the welding position. The fixing of the top electrode holder 5’ in the welding position takes place with the aid of a fixing device 30.

® . 8 PCT/AT02/00035 ’ To every push rod frame 28 two side plates 31 are fastened, which produce a mechanical fixed connection between the top welding head 3’ and the bottom welding head 4’. The fastening of the side plates 31 comprises a swivel guide 32, which makes it possible to swivel the top and bottom welding heads 3’, 4’ out of the welding plane S-S for maintenance purposes or when this welding unit 2 is not : used. Also fastened to the side plates 31 are the longitudinal wire guides 21, 21°.

The bottom welding head 4’ rests on a stationary support centre part 33 of the machine frame of the welding machine, which extends horizontally transversely to the longitudinal wire advancing direction P1, wherein the support centre part 33 has a longitudinal groove 34, in which a sliding block 35 of the fixing device 36 of the bottom welding head 4’ slides. To move the bottom welding head 4’ horizon- tally in the direction transversely to the longitudinal wire direction P1, the fixing device 36 is loosened, the bottom welding head 4’ is moved into its new welding position and fixed in this position with the aid of the fixing device 36.

The power supply of the top electrode holder 5’ and of the bottom electrode holder 6’ takes place by means of a two-wire power cable 37, which is connected to the welding transformer. The power connection to the top electrode holder 5’ takes place with the aid of a current bridge 14’, which is arranged, seen in the production direction P1, on the inlet side of the longitudinal wire sheaf L in front of the welding plane S-S, passes through the longitudinal wire feeding plane E-E and in the area of the longitudinal wires L has suitable through-openings for these.

The current bridge 14’ is connected to the top movable electrode holder 5’ by a flexible current lead 15. The bottom electrode holder 6’ and the current bridge 14’ are electrically separated by an insulating layer 16’, while the current bridge 14’ and the support centre part 33 are electrically separated by an insulating layer 16°’.

With the aid of the fixing device 37, the bottom electrode holder 6’, the current bridge 14’ and the support centre part 33 are fixedly connected to one another in the welding position.

® . 9 PCT/AT02/00035 : The feeding of the longitudinal wires L and of the cross-wire Q1 and Q2 to the movable welding unit 2 essentially corresponds to the feeding to the stationary welding unit 1 described in Fig. 1. However, because the welding units 2 can be moved horizontally, also the longitudinal wire feeders 21, 21’, the cross-wire feeder arms 22, 22’ and the cross-wire flaps 24, 24’ must be made to move hori- zontally together with the welding units 2. Every top cross-wire flap 24 is mounted swivelable in the directions of the double arrow P3 in a bearing 38 fastened in the side plates 31. Every bottom cross-wire flap 24’ is mounted swivelable in the directions of the double arrow P3’ in a bearing 38’ fastened in the side plates 31.

All top cross-wire flaps 24 are opened by an actuating unit 39 extending over the entire operating width of the welding machine, which unit is arranged stationary on the machine frame of the welding machine. The closing of the top cross-wire flaps 24 takes place by an air hose 40 filled with compressed air, which also extends over the entire operating width of the welding machine and which either constantly under pressure acts only passively as a spring element or is actively pneumatically operated. A centring lug 41 per side plate 31 ensures the lateral guiding of the welding unit 2 during the moving.

All bottom cross-wire flaps 24’ are opened by an actuating unit 39’ extending over the entire operating width of the welding machine, which unit is arranged stationary on a fastening bracket 42 of the machine frame of he welding machine. The closing of the bottom cross-wire flaps 24’ also takes place by an air hose 40’ filled with compressed air, which also extends over the entire operating width of the welding machine and which either constantly under pressure acts only passively as a spring element or is actively pneumatically operated.

In Fig. 3a the movement devices for producing the movement paths P4, P5 during the feeding of the cross-wires Q1 and Q2 from the cross-wire channels 23, 23’ into the positions Q1’ and Q2' respectively in the welding plane S-S for the movable welding units 2 are described in more detail. The top cross-wire feeder arms 22 are arranged movable on a top feeder bar 43, which extends horizontally parallel to the welding plane S-S over the entire operating width of the welding

® . 10 PCT/AT02/00035 machine. The moving takes place along a dovetail guide 44 of the top feeder bar 43 and the fixing of the feeder arms 22 in the respective welding position takes place with the aid of a clamp fastener 45. The bottom cross-wire feeder arms 22’ are arranged movable on a bottom feeder bar 46, which extends horizontally parallel to the welding plane S-S over the entire operating width of the welding machine. The moving takes place here along a dovetail guide 44’ of the bottom feeder bar 46 and the fixing of the feeder arms 22 in the respective welding position takes place with the aid of a clamp fastener 45’.

The two feeder bars 43, 46 are each mounted at their ends swivelable in a bearing 47, which in each case is arranged at one end of a one-armed, outside advancing lever 48. The other end of the outside advancing lever 48 is in each case connected in a non-turning manner to a stationary shaft 49 extending over the operating width of the welding machine, which is mounted swivelable in the side plates of the machine frame of the welding machine. Also connected to the shaft 49 in a non-turning manner is a one-armed, inside advancing lever 50, at the free end of which a cam follower 51 is arranged. The cam follower 51 rests on an advancing cam 52, which is fixedly connected to a drive shaft 53 that turns continuously in the arrow direction P6. To avoid a lifting of the cam follower 51 from the advancing cam 52, the inside advancing lever 50 is pressed against it with the aid of a working cylinder, which engages the inside advancing lever 50 at the contact point 54.

Also connected in a non-turning manner to the drive shaft 53 is a tilting cam 55, which is arranged in a fixed relation to the advancing cam 52. One end of a one-armed, inside tilting lever 56 is connected in a non-turning manner to a revolving shaft 57 mounted in the machine frame of the welding machine. The free end of the inside tilting lever 56 carries a roller 58 which rests on the tilting cam 55. To avoid a lifting of the roller 58 from the tilting cam 55, the inside tilting lever 56 is pressed against it with the aid of a working cylinder, which engages the inside tilting lever 56 at the contact point 59. Also connected to the shaft 57 in a non-turning manner is a one-armed, outside tilting lever 60, the free end of which

® . 11 PCT/AT02/00035 has one connection point 61 and 61’ for each of a cylinder bracket 62 and 62’ respectively. The cylinder bracket 62 carries a working cylinder 63, which at the connection point 64 is connected to the top feeder bar 43. The cylinder bracket 62’ carries a working cylinder 63°, which at the connection point 64’ is connected to the bottom feeder bar 46. Both working cylinders 63, 63’ are acted upon by compressed air and serve as spring elements so as to softly cushion the movement of the cross-wires Q1, Q2 in the area of the welding plane S-S at the end of the movement paths P4, P5.

The movement devices for feeding the cross-wires Q1, Q2 to the stationary welding units 1 are identical to the movement devices described for the movable welding units 2. Because the stationary welding units 1 are not moved and always remain stationary, the dovetail guides 44, 44’ and the clamp fasteners 45, 45’ for the cross-wire feeder arms 22, 22’ can fall away.

Fig. 3b illustrates the exact course of the feeder paths P4 and P5 from their starting positions A and A’ via the cross-wire channels 23, 23’ to the respective welding positions Q1°, Q2’ in the welding plane S-S.

The top cross-wire Q1 and the bottom cross-wire Q2 are fed simultaneously in the following manner:

By turning the drive shaft 53, the advancing cam 52 and the tilting cam 55 are turned along in the arrow direction P6 in a fixed relation to one another, wherein the two movement paths P4 and P5 are a combination of simultaneous advancing and tilting movements of the feeder arms 22, 22’. The portion of the advancing movement is produced here by the advancing cam 52, the inside advancing lever 50 and the outside advancing lever 48, whereas the portion of the tilting movement is produced by the tilting cam 55, the inside tilting lever 56 and the outside tilting lever 60.

To feed the cross-wires Q1, Q2, the inside advancing lever 50 is lowered by the corresponding shape of the advancing cam 52, as a result of which the outside

® . 12 PCT/AT02/00035 advancing levers 48 are swivelled in the direction of the welding plane S-S, so that the feeder arms 22, 22’ also move in the direction of the welding plane S-S. At the same time the inside tilting lever 56 is lifted by the corresponding shape of the tilting cam 55, as a result of which the outside tilting lever 60 moves upwards, sO that the top feeder arms 22 are swivelled downwards, whereas the bottom feeder arms 22’ are swivelled upwards. During the feeding movement every fork 26 of the top feeder arm 22 grips the top cross-wire Q1 positioned in the top cross-wire channel 23, removes it in the transverse direction out of the cross-wire channel 23 and moves it, guided by the top cross-wire guide 27, downwards up to the longitudinal wires L and along the longitudinal wires L up to the welding position

Q1’ in the welding plane S-S. The horizontal course of the movement path P4 in the area of the longitudinal wires L is produced by the fact that the top cross-wire

Q1 is not held tight by the fork 26, but can freely fall downwards onto the longitudinal wires L. The feeding movement of the bottom feeder arm 22’ for feeding the bottom cross-wire Q2 essentially takes place in the same manner and simultaneously with the feeding of the top cross-wire Q1. During the feeding movement every fork 26 of the bottom feeder arm 22’ grips the bottom cross-wire

Q2 positioned in the bottom cross-wire channel 23’, removes it in the transverse direction out of the cross-wire channel 23’ and moves it, guided by the bottom cross-wire guide 27’, upwards up to the welding position Q2’ in the welding plane

S-S, wherein the bottom cross-wires Q2 are placed on the bottom electrodes 8, 8’.

By a suitable shaping of the advancing cam 52 and tilting cam 55, the forks 26 of the feeder arms 22, 22’, notwithstanding the continuous turning movement of the drive shaft 53, remain in the welding positions Q1’, Q2’ until the cross-wires

Q1, Q2 have been clamped tight by the top electrodes 7, 7° and the bottom electrodes 8, 8’. After the clamping tight of the cross-wires Q1, Q2, the feeder arms 22, 22’ are returned to their starting position A, A’ as follows: The inside advancing lever 50 is lifted by the corresponding shape of the advancing cam, as a result of which the outside advancing levers 48 are swivelled away from the welding plane S-S, so that the feeder arms 22, 22’ also move away from the

® . 13 PCT/AT02/00035 welding plane S-S. At the same time the inside tilting lever 56 is lowered by the corresponding shape of the tilting cam 55, as a result of which the outside tilting lever 60 moves downwards, so that the top feeder arms 22 are swivelled upwards, whereas the bottom feeder arms 22’ are swivelled downwards.

Fig. 3b in addition illustrates diagrammatically for the top cross-wire channel 23 several top cross-wire brake levers 65 and for the bottom cross-wire channel 23’ several bottom cross-wire brake levers 65’, which each comprise at their end a brake shoe 66, with the aid of which during the cutting of the respective cross- wire Q1, Q2 from the fed material strands, the cross-wire Q1, Q2 is held tight in the respective cross-wire channel 23, 23’. Per welding unit 1 and 2 respectively, a top and a bottom cross-wire brake lever 65, 65’ is provided. During the moving of the cross-wires Q1, Q2 out of the cross-wire channels 23, 23’, the cross-wire brake levers 65, 65’ are swivelled away in the directions of the double arrows P7,

P7’, and then swivelled back again into their starting position.

The machine according to the invention operates as follows:

Along the longitudinal wire feeding plane E-E, the longitudinal wires are fed in a fixed cycle, in the desired longitudinal wire spacing, guided by the longitudinal wire guides 21, 21’, in the arrow direction P1 to the welding units 1, 2 in the welding plane S-S. At the same time the top cross-wire Q1 and the bottom cross- wire Q2 are shot perpendicularly to the longitudinal wire feeding direction P1 into the cross-wire channels 23, 23’ and cut off from the material strand. By the movement mechanism described in the foregoing, the feeder arms 22, 22’ grip the cross-wires Q1, Q2, remove them from the cross-wire channels 23, 23’ and bring them into the welding plane S-S, where they are arranged above and underneath the longitudinal wires L, exactly vertically above one another, on and under the longitudinal wires L respectively. As soon as the cross-wires Q1, Q2 have left the cross-wire channels 23, 23’, new cross-wires can be fed into them. For welding the cross-wires Q1’, Q2’ to the longitudinal wires L, the electrode holders 5, 5’ are moved downwards in the corresponding direction of the double arrow P2 until the cross-wires Q1’, Q2’ are clamped tight between the welding electrodes 7, 7’; 8,

® . 14 PCT/AT02/00035 8" and the longitudinal wires L. At this moment the forks 26 of the feeder arms 22, 22’ detach themselves from the cross-wires Q1’, Q2’ and move back into their starting positions A, A’, so as to be ready to pick up new cross-wires. The top electrode holders 5, 5’ are acted upon by the required welding pressure, the welding current is switched on and with the aid of the welding electrodes 7, 7’; 8, 8’, the cross-wires Q1, Q2 are welded to the longitudinal wires L. After the welding has taken place, the welding current is switched off and the top electrode holders 5, 5° move upwards, as a result of which the pressure on the crossing points of the cross-wires with the longitudinal wires is released, and the crossing points come loose from the top electrodes 7, 7’. Because of the spring-mounted design of the longitudinal wire feeders 21, 21’, the wire mesh mat G is lifted slightly, so that the crossing points also come loose from the bottom electrodes 8, 8’. The wire mesh mat G is then pulled out of the welding plane S-S in the arrow direction P1 until the desired distance has been reached, so that in a next operating cycle further cross-wires Q1, Q2 can be welded to the longitudinal wires L. The top electrodes 7, 7’ are only lifted so far until the opening between the longitudinal wires L and the welding electrodes 7, 7’; 8, 8’ is large enough to be able to feed further cross-wires Q1, Q2 into the welding plane S-S.

To produce wire mesh mats G with different longitudinal wire spacings, the movable welding units 2 are beforehand moved into their new welding positions perpendicular to the longitudinal wire feeding direction P1 and fixed in position there, wherein the corresponding fixing devices 36 for the bottom welding heads 4', as well as the clamp fasteners 45, 45’ for the top and bottom feeder arms 22, 22’ must be actuated.

It goes without saying that the illustrated exemplified embodiments can be variously modified within the framework of the general idea of the invention, especially with regard to the design and execution of the feeder arms and the movement devices of the feeder arms. The movements of the feeder arms can take place by separate drives, which must however be synchronised by suitable control measures. Furthermore, the forks of the feeder arms can be made as tongs-like

® . 15 PCT/AT02/00035 gripping elements so as to accurately guide the cross-wires during their feeding movement. Moreover, it is possible within the framework of the invention to feed cross-wires Q1, Q2 that have been cut to length beforehand into the cross-wire channels 23, 23’, wherein the feeding can take place either perpendicular to the longitudinal wire advancing direction P1 from the side or parallel to the longitudinal wire feeding direction P1.

With the aid of suitable control elements, the turning movement of the drive shaft 53 for the advancing cam 52 and tilting cam 55 can be synchronised with the movements for feeding the cross-wires Q1, Q2 into the cross-wire channels 23, 23’ and the advancing movements of the longitudinal wires L and of the wire mesh mat G. By this synchronised control of all movements of the mesh welding machine, these are optimally adapted to one another and any dead times in the production cycle are avoided.

Claims

® . 16 PCT/AT02/00035 CLAIMS

1. Multispot welding machine operating according to the electrical resistance method, for producing wire mesh mats from a sheaf of parallel longitudinal wires and cross-wires crossing the former at a right angle, which are arranged above and underneath the longitudinal wires opposite one another and are welded to the longitudinal wires, with a cross-wire channel each arranged above and underneath a horizontal longitudinal wire feeding plane on the outlet side of the finished welded wire mesh mat, with cross-wire feeders that feed the cross-wires from the cross-wire channels into the welding plane between the sheaf of longitudinal wires and rows of top welding electrodes and bottom welding electrodes, that can be raised and lowered, arranged on either side thereof, and with a current bridge each for the top electrodes passing through the longitudinal wire feeding plane, characterised in that a cross-wire channel (23, 23’) each above and underneath the longitudinal wire feeding plane (E-E) is arranged, seen in the production direction (P1), on the inlet side of the sheaf of longitudinal wires (L) in front of the welding plane (S-S) defined by the top and bottom electrodes, that every cross-wire feeder comprises a simultaneously swivel- able and advanceable feeder arm (22, 22’), and that the two feeder arms (22, 22’) in a synchronous feeding movement (P4, P5) simultaneously move the cross-wires (Q1, Q2) from the cross-wire channels (23, 23’) into the welding plane (S-S), wherein the top cross-wire (Q1) is placed on the longitudinal wires (L) and the bottom cross-wire (Q2) on the bottom electrodes (8, 8’).

2. Mesh welding machine according to claim 1, characterised in that every feeder arm (22, 22’) has at its free end a V-shaped fork (26) for gripping a cross-wire (Q1, Q2).

® 17 PCT/AT02/00035

3. Mesh welding machine according to claim 1 or 2, characterised in that the cross-wire channels (23, 23’) are arranged between the current bridge (14, : 14’) and the top electrodes (7, 7’) and bottom electrodes (8, 8’) respectively.

4, Mesh welding machine according to any one of the claims 1 to 3, characterised in that the feeder arms (22, 22’) execute a simultaneous advancing and tilting movement (P4, P5), wherein a movement device is provided which is controlled by an advancing cam (52) and a tilting cam (55), which are arranged in a fixed relation in a non-turning manner on a common, continuously driven (P6) drive shaft (53).

5. Mesh welding machine according to claim 4, characterised in that every feeder arm (22, 22’) is fastened on one each jointly mounted (47) feeder bar (43, 46), wherein every feeder bar (43, 46) can be simultaneously swivelled and moved ahead (P4, P5) by inside (52) and outside (48) advancing levers, mounted jointly in a non-turning manner and controlled by the advancing cam (53), as well as by inside (54) and outside (60) tilting levers, mounted jointly in a non-turning manner and controlled by the tilting cam (55).

6. Mesh welding machine according to claim 4 or 5, characterised in that for the soft cushioning of the cross-wires (Q1, Q2) during the positioning in the welding positions (Q1’, Q2’), the outside tilting lever (60) is connected to each of the feeder bars (43, 46) by a spring element (62, 62°).

7. Mesh welding machine according to any one of the claims 4 to 6, characterised in that the advancing cam (52) and the tilting cam (55) are designed in such a way that after placing the cross-wires (Q1, Q2) in their welding positions (Q1’, Q2') in the welding plane (S-S), notwithstanding the continuous driving of the drive shaft (53), the feeder arms (22, 22’) stand still until the cross-wires (Q1, Q2) are securely clamped tight between the longitudinal wires (L) and the top and bottom electrodes (7, 7’; 8, 8’).

® 18 PCT/AT02/00035

8. Mesh welding machine according to any one of the claims 4 to 7, characterised in that the turning movement of the drive shaft (53) for the advancing cam (52) and tilting cam (55) is adapted to the movements for feeding the cross-wires (Q1, Q2) into the cross-wire channels (23, 23’) and with the advancing movements of the longitudinal wires (L) and the wire mesh mat (G) with the aid of a central control unit.

9. Mesh welding machine according to any one of the claims 1 to 8, characterised in that the cross-wires (Q1, Q2) during the feeding are guided by guides (27, 27).

10. Mesh welding machine according to any one of the claims 1 to 9, characterised in that the cross-wire channels (23, 23’) can be closed off by cross-wire flaps (24, 24’) that can be swivelled away (P3, P3’) and in that the cross-wire channels (23, 23’) comprise several brake levers (65, 65’) with brake shoes (66) for stopping the cross-wires (Q1, Q2) during the cutting off from the material strand.

11. Mesh welding machine according to any one of the claims 1 to 10, characterised in that, in order to change the longitudinal wire spacing, the top electrodes (7, 7°) are arranged in a top welding head (3’) that can be moved horizontally in the welding plane {S-S) and the bottom electrodes (8, 8’) in a bottom welding head (4) that can be moved horizontally in the welding plane (S-S), wherein the top welding head (3’) and the bottom welding head (4') are connected by two side plates (31), and in that the feeder arms (22, 22’), each with the aid of a clamp fastener (45, 45’), are arranged in such a way that they can be moved horizontally parallel to the welding plane and be fixed on their feeder bar (43, 46).

\ ® 19 PCT/AT02/00035

12. Mesh welding machine according to claim 11, characterised in that the longitudinal wire guides (21, 21’) are arranged in the side plates (31) and in that the longitudinal wire guides (21, 21’), the cross-wire guides (27, 27’), the cross-wire flaps (24, 24’) and the brake levers (65, 65’) can be moved jointly with the welding heads (3’, 4’) horizontally parallel to the welding plane (S-S).