CN113600989B

CN113600989B - Welding host and welding equipment

Info

Publication number: CN113600989B
Application number: CN202110971532.XA
Authority: CN
Inventors: 陈罗; 裴娟苗
Original assignee: Zhuhai Zhuxiang Cloud Technology Co ltd
Current assignee: Sany Zhugong Technology Miluo Co ltd
Priority date: 2021-08-20
Filing date: 2021-08-20
Publication date: 2023-05-12
Anticipated expiration: 2041-08-20
Also published as: CN113600989A

Abstract

The invention relates to the technical field of reinforcing mesh welding, in particular to a welding host and welding equipment. The welding host computer includes frame and electrode assembly, and electrode assembly includes: two groups of first electrode assemblies arranged on the frame, wherein each first electrode assembly comprises a plurality of first electrodes which are electrically connected; the second electrode assembly is arranged on the rack and comprises a plurality of second electrodes which are electrically connected, and the second electrodes are arranged in one-to-one correspondence with the first electrodes; the transformer is provided with an anode and a cathode, wherein the anode is connected with one group of first electrode assemblies, and the cathode is connected with the other group of first electrode assemblies; the movable electrode assembly comprises a movable electrode and a driving piece, wherein the movable electrode is movably arranged on the rack and is correspondingly arranged with the pair of first electrodes and the second electrodes, and the driving piece is connected with the movable electrode so as to enable the movable electrode to be contacted with or far away from the corresponding first electrodes and second electrodes. The invention can conduct two electrodes through the movable electrode during single-point welding, thereby avoiding serious damage to the electrodes and the reinforcing steel bars.

Description

Welding host and welding equipment

Technical Field

The invention relates to the technical field of reinforcing mesh welding, in particular to a welding host and welding equipment.

Background

The reinforcing steel bar mesh welding host is automatic welding equipment for welding reinforcing steel bars in the longitudinal and transverse directions into a grid shape, the reinforcing steel bar mesh welding host is pressurized on the reinforcing steel bars which are longitudinally and transversely crossed in the welding process, and the reinforcing steel bars are directly contacted with the longitudinal bars and the transverse bars through electrode heads which are arranged up and down, and the longitudinal bars and the transverse bars are welded.

At present, the welding host comprises upper electrodes and lower electrodes which are arranged in pairs, each pair of upper electrodes and lower electrodes is provided with a transformer, when welding spots are more, a plurality of pairs of upper electrodes and lower electrodes exist, one transformer can only weld one spot at a time, the production efficiency is low, the number of transformers is large, the number of independent conductive loops is large, the structure is complex, the production cost is high, and the maintenance cost is also high.

In order to improve production efficiency, the welding host adopts the mode of establishing ties to weld two points simultaneously, when there is not the longitudinal reinforcement between upper electrode and the lower electrode of pair, then need electrically conduct through horizontal muscle, can produce the spark between upper electrode and horizontal muscle when welding, cause the damage to upper electrode and horizontal muscle, influence the intensity of reinforcing bar net piece, upper electrode damage is serious, and electrode change frequency is high, and manufacturing cost is high.

Disclosure of Invention

The invention mainly aims to provide a welding host and welding equipment, which are used for solving the problem that the upper electrode and the transverse ribs are seriously damaged when the transverse ribs conduct electricity in the prior art.

In order to achieve the above object, the present invention provides a welding host, including a frame and an electrode device, the electrode device includes: two groups of first electrode assemblies are arranged on the rack, and each group of first electrode assemblies comprises a plurality of first electrodes which are arranged side by side and are electrically connected; the second electrode assembly is arranged on the rack and comprises a plurality of second electrodes which are arranged side by side and are electrically connected, and the second electrodes are arranged in one-to-one correspondence with the first electrodes; the transformer is provided with an anode and a cathode, wherein the anode is connected with one group of first electrode assemblies, and the cathode is connected with the other group of first electrode assemblies; the movable electrode assembly comprises a movable electrode and a driving piece, wherein the movable electrode is movably arranged on the rack and is correspondingly arranged with the pair of first electrodes and the second electrodes, and the driving piece is connected with the movable electrode so as to enable the movable electrode to be contacted with or far away from the corresponding first electrodes and second electrodes.

Optionally, the movable electrode is movably disposed on the housing.

Optionally, the driving member is a telescopic cylinder.

Alternatively, the movable electrode is swingably provided on the frame.

Optionally, the driving member is a rotary cylinder.

Alternatively, two movable electrode assemblies are provided, and the two movable electrode assemblies are respectively arranged corresponding to one first electrode in the two groups of first electrode assemblies.

Optionally, the welding host further includes a fixed electrode fixed to one of the pair of first and second electrodes, the movable electrode being disposed proximate the other of the pair of first and second electrodes.

Optionally, the transformer is disposed on a side of the first electrode remote from the second electrode.

Optionally, the second electrode assembly further comprises a second electrode holder, and the plurality of second electrodes are mounted on the second electrode holder.

The invention also provides a welding device comprising: the welding host machine.

The technical scheme of the invention has the following advantages: when the first electrodes in one group of first electrode assemblies and the corresponding second electrodes are simultaneously provided with longitudinal ribs and transverse ribs, and the first electrodes in the other group of first electrode assemblies and the corresponding second electrodes cannot simultaneously meet the conditions that the longitudinal ribs and the transverse ribs are arranged, the movable electrodes corresponding to the first electrodes in the other group of first electrode assemblies are driven to move, when the two first electrodes are simultaneously pressed down, the first electrodes in one group of first electrode assemblies, the corresponding second electrodes, the transverse ribs and the longitudinal ribs, and the first electrodes in the other group of first electrode assemblies, the corresponding second electrodes and the movable electrodes form a series welding loop, the first electrodes and the second electrodes can be conducted through the movable electrodes in the single-point welding process, the condition that the electrodes and the transverse ribs are seriously damaged when the transverse ribs are conducted is avoided effectively, the service life of the first electrodes is prolonged, the electrode frequency is low, and the production cost is reduced effectively.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a partial perspective view of a first embodiment of a welding host of the present invention;

FIG. 2 shows an enlarged schematic view of the welding host machine of FIG. 1 at A;

FIG. 3 illustrates a schematic front view of the welding host of FIG. 1;

FIG. 4 illustrates a side schematic view of the welding host of FIG. 1;

FIG. 5 illustrates a schematic diagram of the welding host of FIG. 1;

FIG. 6 is a schematic diagram showing the principle of conduction of two pairs of upper and lower electrodes of the welding host of FIG. 5 through transverse and longitudinal ribs;

FIG. 7 is a schematic diagram showing the principle of conducting one pair of upper and lower electrodes through transverse and longitudinal ribs and another pair of upper and lower electrodes through movable electrodes of the welding host of FIG. 5;

FIG. 8 illustrates a side view schematic of a movable electrode assembly of the welding host of FIG. 1;

fig. 9 shows a side view of a movable electrode assembly of a second embodiment of a welding host of the present invention.

Reference numerals illustrate:

10. a frame; 11. a right body; 12. an upper cross beam; 13. a lower cross beam; 20. a first electrode assembly; 21. a first electrode; 30. a second electrode assembly; 31. a second electrode; 40. a transformer; 50. a movable electrode assembly; 51. a movable electrode; 52. a driving member; 53. a fixing plate; 60. fixing the electrode; 71. longitudinal ribs; 72. transverse ribs.

Detailed Description

The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.

Example 1

As shown in fig. 1 to 5, the welding host of the present embodiment includes: a housing 10 and an electrode assembly comprising: two sets of first electrode assemblies 20, a second electrode assembly 30, a transformer 40 and a movable electrode assembly 50, wherein the two sets of first electrode assemblies 20 are arranged on the frame 10, and each set of first electrode assemblies 20 comprises a plurality of first electrodes 21 which are arranged side by side and are electrically connected; the second electrode assembly 30 is arranged on the frame 10, the second electrode assembly 30 comprises a plurality of second electrodes 31 which are arranged side by side and are electrically connected, and the second electrodes 31 are arranged in one-to-one correspondence with the first electrodes 21; the transformer 40 has an anode connected to one set of the first electrode assemblies 20 and a cathode connected to the other set of the first electrode assemblies 20; the movable electrode assembly 50 includes a movable electrode 51 movably disposed on the frame 10 and disposed in correspondence with the pair of first and

second electrodes

21 and 31, and a driving member 52 connected to the movable electrode 51 so that the movable electrode 51 contacts or is spaced apart from the corresponding first and

second electrodes

21 and 31.

When the welding host machine of the embodiment is applied, the longitudinal ribs 71 and the transverse ribs 72 are simultaneously formed between the first electrodes 21 in one group of first electrode assemblies 20 and the corresponding second electrodes 31, and when the longitudinal ribs 71 and the transverse ribs 72 cannot be simultaneously met between the first electrodes 21 in the other group of first electrode assemblies 20 and the corresponding second electrodes 31, the movable electrodes corresponding to the first electrodes 21 in the other group of first electrode assemblies 20 are driven to move, when the two first electrodes 21 are simultaneously pressed down, the first electrodes 21 in one group of first electrode assemblies 20, the corresponding second electrodes 31, the transverse ribs 72, the longitudinal ribs 71, the first electrodes 21 in the other group of first electrode assemblies 20, the corresponding second electrodes 31 and the movable electrodes 51 form a series welding circuit (as shown in fig. 7), and the structure can conduct the two electrodes through the movable electrodes in single-point welding without conducting through the transverse ribs, so that severe damage to the electrodes and the transverse ribs is effectively avoided, the strength of the electrodes is ensured, the service life of the first electrodes is prolonged, the production cost is effectively reduced, and the production cost of the first electrodes is effectively reduced. When there are longitudinal ribs and transverse ribs between the first electrodes 21 of the two groups of first electrode assemblies 20 and the corresponding second electrodes 31, when the first electrodes 21 of the two groups of first electrode assemblies 20 are pressed down simultaneously, the first electrodes 21 of one group of first electrode assemblies 20 and the corresponding second electrodes 31, transverse ribs and longitudinal ribs thereof, and the first electrodes 21 of the other group of first electrode assemblies 20 and the corresponding second electrodes 31, transverse ribs and longitudinal ribs thereof form a series welding loop (as shown in fig. 6), and one welding loop can weld two points simultaneously.

In the present embodiment, as shown in fig. 1, 2 and 8, the movable electrode 51 is movably provided on the frame 10. The movable electrode 51 is driven to move by the driving piece 52, so that the movable electrode 51 is contacted with or separated from the first electrode 21 and the second electrode 31, and when the movable electrode 51 is contacted with the corresponding first electrode 21 and second electrode 31, the first electrode 21 and the second electrode 31 can be contacted and conducted by the movable electrode 51, and the situation that the first electrode and the transverse ribs are seriously damaged when conducting by the transverse ribs is effectively avoided.

In this embodiment, the driving member 52 is a telescopic cylinder, a piston rod of the telescopic cylinder is connected with the movable electrode 51, and the linear motion of the movable electrode is realized through the telescopic motion of the piston rod, so that the cylinder is convenient to use and low in cost. As an alternative embodiment, the driving member is a telescopic cylinder or a linear motor, etc.

In this embodiment, the movable electrode assembly 50 further includes a fixing plate 53, the driving member 52 is fixed on the fixing plate 53, and the fixing plate 53 is fixedly connected to the second electrode 31, so that the fixing is simple. Alternatively, the driving member 52 may be directly secured to the frame.

In the present embodiment, two movable electrode assemblies 50 are provided, and the two movable electrode assemblies 50 are provided corresponding to one first electrode 21 of the two sets of first electrode assemblies 20, respectively. The movable electrode 51 is correspondingly arranged on one first electrode 21 in each group of first electrode assemblies 20, so that the method can be applied to the situation that transverse ribs and longitudinal ribs cannot be simultaneously met between two pairs of first electrodes and two pairs of second electrodes.

It should be noted that, when the first electrodes of the two sets of first electrode assemblies 20 and the corresponding second electrodes have the transverse ribs and the longitudinal ribs, the movable electrodes of the two sets of movable electrode assemblies 50 are respectively away from the corresponding first electrodes and second electrodes; when the transverse ribs and the longitudinal ribs cannot be met between the first electrodes and the second electrodes corresponding to one group of movable electrode assemblies 50, the driving piece of the group of movable electrode assemblies 50 drives the movable electrodes to move, so that the movable electrodes are in contact with the first electrodes and the second electrodes corresponding to the movable electrodes, and the movable electrodes of the other group of movable electrode assemblies 50 are far away from the first electrodes and the second electrodes corresponding to the movable electrodes.

In this embodiment, the welding host further includes a fixed electrode 60, the fixed electrode 60 is fixed on the first electrode 21 of the pair of first electrodes 21 and second electrodes 31, the movable electrode 51 is disposed near the second electrode 31 of the pair of first electrodes 21 and second electrodes 31, and the fixed electrode 60 is disposed to facilitate the conduction between the first electrode and the movable electrode. Alternatively, the fixed electrode may not be provided, or the fixed electrode may be provided and fixed to the second electrode of the pair of first and second electrodes, and the movable electrode may be provided near the first electrode of the pair of first and second electrodes.

In this embodiment, as shown in fig. 1, the transformer 40 is disposed on the side of the first electrode 21 away from the second electrode 31, and the required copper connection is short, low in cost, short in conductive loop, and high in welding quality.

In the present embodiment, the second electrode assembly 30 further includes a second electrode holder on which a plurality of second electrodes 31 are mounted. Because the positive pole and the negative pole of the transformer are communicated with the first electrode, a plurality of second electrodes 31 only need to be arranged on one second electrode seat and are conducted through the second electrode seat, any copper strips, copper plates and the like do not need to be connected, and the structure is compact and simple, and the cost is low. The electrode device is provided with a plurality of second electrode holders of a plurality of second electrode assemblies 30 which can be integrally formed, namely, the second electrodes of the plurality of electrode devices are arranged on one second electrode holder and are mutually conducted through the second electrode holder.

In this embodiment, a plurality of electrode devices are arranged in proper order, can weld the unidimensional net piece, and equipment availability factor is high.

In this embodiment, the number of the first electrodes 21 and the number of the second electrodes 31 of each electrode device are equal and are even, the first electrodes 21 are divided into two groups, the first electrodes 21 between each group are mutually conducted through a soft copper strip and a copper bar, one group of the first electrode assemblies 20 is connected with the positive pole of the secondary winding of the transformer 40, and the other group of the first electrode assemblies 20 is connected with the negative pole of the transformer 40.

In the present embodiment, as shown in fig. 1, the frame 10 includes a left body, a right body 11, an upper beam 12, a lower beam 13, and the like, and the upper beam 12 and the lower beam 13 are connected to the left body and the right body 11, respectively; the number of transformers 40 and the number of electrode devices are 1, 2, 3 or 4 or more, and the transformers 40 are fixed to the upper portion of the frame 10.

In this embodiment, the first electrode assembly is disposed above the second electrode assembly 30, and the first electrode assembly is an upper electrode assembly, and the second electrode assembly 30 is a lower electrode assembly.

It will be appreciated that the upper electrode assembly includes an upper electrode, a cylinder, an upper electrode holder, a longitudinal rib limiting device, etc., the upper electrode is fixed on the upper beam 12 through the upper electrode holder, the welding action is realized through the extension and contraction of the cylinder, the number of the upper electrodes of each electrode device is even, the upper electrodes are equally divided into two groups, the upper electrodes in each group of upper electrode assemblies are mutually communicated through a copper plate, one group of upper electrode assemblies is connected with the positive pole of the secondary winding of the transformer 40, and the other group of upper electrode assemblies is connected with the negative pole of the transformer.

It will be appreciated that the lower electrode assembly is fixed on the lower beam 13, and the lower electrode assembly includes lower electrode holders, lower electrodes, etc., the number of the lower electrodes is the same as and corresponds to the number of the upper electrodes one by one, and all the lower electrodes are mounted on one lower electrode holder and are conducted with each other through the lower electrode holder.

It will be appreciated that the movable electrode assemblies 50 are also fixed on the lower beam 13, the movable electrode assemblies 50 include movable electrodes 51 and cylinders, the number of the movable electrode assemblies 50 is the same as that of the upper electrode assemblies, one movable electrode assembly 50 corresponds to one group of upper electrode assemblies, the movable electrodes 51 can move to the lower electrodes through the expansion and contraction of the cylinders, and when the upper electrodes are pressed down, the upper electrodes and the lower electrodes can be conducted.

It will be appreciated that the transformer 40 is disposed above the first electrode 21, requiring a short copper connection, low cost, short conductive loop, and high weld quality.

Note that, the solid circles above the horizontal ribs 72 in fig. 5 to 7 refer to the vertical ribs 71, the dotted circles above the horizontal ribs 72 in fig. 5 to 7 refer to another position where the vertical ribs 71 may be placed, and two vertical rib limiting grooves are provided on the upper electrode at this time, so that the position of the vertical ribs 71 may be adjusted according to the specific situation.

Example two

As shown in fig. 9, the welding host of the second embodiment is different from the first embodiment in that the movement mode of the movable electrode 51 is different, in the second embodiment, the movable electrode 51 is swingably disposed on the frame 10, and the movable electrode 51 is driven to swing by the driving member 52, so as to achieve contact or separation of the movable electrode 51 from the upper electrode and the lower electrode.

In the present embodiment, the driving member 52 is a rotary cylinder, an output shaft of which is connected to the movable electrode 51, and the swing of the movable electrode is achieved by the rotary motion of the output shaft. As an alternative embodiment, the driving member is a motor or the like.

As an alternative embodiment, the first electrode assembly is disposed below the second electrode assembly, where the first electrode assembly is a lower electrode assembly and the second electrode assembly is an upper electrode assembly, the upper electrode assembly includes a plurality of upper electrodes, the lower electrode assembly is provided with two groups each including a plurality of lower electrodes, the lower electrodes of each group of lower electrode assemblies are conducted with each other, the transformer is disposed below the lower electrode assemblies, and all the upper electrodes are conducted with each other.

The present invention also provides a welding apparatus comprising: the welding host machine. When the horizontal rib and the vertical rib cannot be met between a pair of upper electrodes and a lower electrode, the movable electrode can move or rotate to the lower electrode through the expansion or rotation of the air cylinder, the upper electrodes and the lower electrodes can be contacted through the movable electrode when the upper electrodes are pressed down, and then a welding loop is conducted, so that the situation that the upper electrodes and the horizontal rib are seriously damaged when the upper electrodes and the lower electrodes are conducted through the horizontal rib is avoided effectively, the strength of a reinforcing steel bar net sheet is ensured, the service life of the electrodes is prolonged, the electrode replacement frequency is low, and the production cost is effectively reduced.

From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

1. the welding host comprises a frame and a plurality of electrode devices, each electrode device comprises an upper electrode, a lower electrode, a transformer, movable electrodes and the like, the upper electrodes are divided into two groups and form upper electrode assemblies, the upper electrodes among the upper electrode assemblies of each group are mutually conducted through a soft copper strip and a copper bar, one upper electrode assembly is connected with the positive electrode of a secondary winding of the transformer, the other upper electrode assembly is connected with the negative electrode of the transformer, the number of the movable electrodes in each electrode device is 2, and the two movable electrodes are respectively and correspondingly arranged with one upper electrode of the two upper electrode assemblies, so that the positive electrode of the transformer can be conducted, and the negative electrode of the transformer can be conducted. When one upper electrode is pressed down in the two groups of upper electrode assemblies and the transverse ribs and the longitudinal ribs are arranged between the lower electrodes corresponding to the upper electrodes, a series welding loop is further formed, two points can be welded at the same time in one conductive loop, and the production efficiency is high; when the condition that transverse ribs and longitudinal ribs are simultaneously unavailable between a pair of upper electrodes and a pair of lower electrodes is met, the movable electrodes corresponding to the upper electrode assemblies without transverse ribs and longitudinal ribs or without longitudinal ribs rotate or move between the upper electrodes and the lower electrodes corresponding to the upper electrode assemblies, when the two upper electrodes are pressed down, a welding loop is formed through the movable electrodes, only one point is welded at the moment, so that the condition that the upper electrodes and the transverse ribs are seriously damaged when the upper electrodes and the lower electrodes are electrically conductive through the transverse ribs is avoided, the strength of a reinforcing mesh is ensured, the service life of the electrodes is prolonged, the electrode replacement frequency is low, the production cost is effectively reduced, and the problems of low welding efficiency, poor welding quality, high cost and the like in the prior art are solved.

2. The transformer is arranged above the upper electrode, and has the advantages of less copper connecting pieces, short conductive loop, simple structure, low cost and high welding quality.

3. All lower electrodes are arranged on the same lower electrode seat and are mutually conducted through the lower electrode seat, any copper strips, copper plates and the like are not needed to be connected, and the structure is compact and simple, and the cost is low.

4. The movable electrode is made of materials with good conductivity, good machining performance and moderate price, such as chromium, zirconium, copper and the like, and the driving piece is a telescopic cylinder, a rotary cylinder and the like.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.

Claims

1. A welding host machine comprising a frame (10) and an electrode arrangement, the electrode arrangement comprising:

two groups of first electrode assemblies (20) arranged on the frame (10), each group of first electrode assemblies (20) comprising a plurality of first electrodes (21) arranged side by side and electrically connected;

the second electrode assembly (30) is arranged on the rack (10), the second electrode assembly (30) comprises a plurality of second electrodes (31) which are arranged side by side and are electrically connected, and the second electrodes (31) are arranged in one-to-one correspondence with the first electrodes (21);

a transformer (40) having a positive electrode connected to one set of the first electrode assemblies (20) and a negative electrode connected to the other set of the first electrode assemblies (20);

a movable electrode assembly (50) comprising a movable electrode (51) and a driving member (52), the movable electrode (51) being movably disposed on the frame (10) and being disposed in correspondence with a pair of the first electrode (21) and the second electrode (31), the driving member (52) being connected to the movable electrode (51) so that the movable electrode (51) is in contact with or away from the corresponding first electrode (21) and second electrode (31), the movable electrode (51) being movably disposed on the frame (10), or the movable electrode (51) being swingably disposed on the frame (10);

the second electrode assembly (30) further comprises a second electrode holder, and a plurality of second electrodes (31) are mounted on the second electrode holder and conducted through the second electrode holder.

2. Welding master according to claim 1, characterized in that the driving element (52) is a telescopic cylinder when the movable electrode (51) is movably arranged on the frame (10).

3. Welding master according to claim 1, characterized in that the driving element (52) is a rotary cylinder when the movable electrode (51) is arranged swingably on the frame (10).

4. A welding host as claimed in any one of claims 1 to 3, wherein two of said movable electrode assemblies (50) are provided, said two movable electrode assemblies (50) being arranged in correspondence with one first electrode (21) of two sets of first electrode assemblies (20), respectively.

5. A welding host as claimed in any one of claims 1 to 3, further comprising a fixed electrode (60), said fixed electrode (60) being fixed to one of a pair of said first (21) and second (31) electrodes, said movable electrode (51) being disposed adjacent to the other of a pair of said first (21) and second (31) electrodes.

6. A welding host as claimed in any one of claims 1 to 3, characterized in that the transformer (40) is arranged on the side of the first electrode (21) remote from the second electrode (31).

7. A welding apparatus, comprising: the welding host of any one of claims 1 to 6.