Welding machine

Abstract

There is provided a welding machine, preferably of the flash welding type, designed to facilitate the maintenance of clamping means 3, 4, 6, 7, for example clamps, for clamping two elongate metal products to be welded. Advantageously, a first structure 2 provided with first clamping means 3, 4 and a second structure 5 provided with second clamping means 6, 7 are supported in a first part 10 of the carriage 1 defined by a first beam 9 and a second beam 8 of the carriage 1 parallel to the feed direction X, and at least one transformer 36 is fixed to the carriage 1 and is supported in a second part 11 of the carriage 1 located laterally outside the first part 10. Further, two upset cylinders 23, 24 are inclined by a non-zero acute angle with respect to the horizontal plane and are located along a plane Y passing through a passage region of the elongate metal product along the feed direction X.

Description

Technical Field

[0001] The present invention relates to a welding machine, preferably of the flash welding type, suitable for welding the ends and tips of two successive long products to each other along a roller table, usually placed upstream of a rolling mill, for long metal products such as billets, bars or blooms.

Background Art

[0002] Particularly in the case of continuous rolling mills, metal products from a casting machine or an external storage location are welded and then continuously rolled.

[0003] The metal products to be welded are typically metallurgical semi-finished products such as billets, bars or blooms.

[0004] Welding is performed by joining the end of one product to the tip of the next product.

[0005] Welding is done by an electric shock generated by a power source connected to the products to be welded. This technique is known as flash welding.

[0006] During welding, the products must be effectively fixed. Therefore, clamping means are provided which serve to keep the products in place during welding and often also act as conductors of the welding current.

[0007] Conventionally, such clamping means include elements that come into direct contact with the products to be welded, especially clamps. During welding, gradually, the clamps holding the tips and ends of the products to be welded are brought closer together by a hydraulic cylinder called an upset cylinder. This operation is necessary to join the ends to be welded in order to eliminate inclusions and air bubbles, to compensate for the loss of material in the form of burrs determined by melting, and to enable effective adhesion between the two members to be welded that form the welded joint.

[0008] Flash welding machines of known designs generally include two structures each provided with a pair of clamps. The structures are substantially parallel to each other and are inclined at an angle of about 45° with respect to the plane defined by the carriage supporting the machine. This inclination enables the clamping force on the product to be applied uniformly to the surface of the product, thereby enabling optimal holding and centering.

[0009] Generally, a transformer provided with conductors connected to the two structures to supply current to the ends and tips of the two products to be welded is arranged on the inclined upper surfaces of the two structures, making access to the internal parts of the machine and consequently its maintenance difficult.

[0010] As described in WO2021156738A1, in recent years, a welding machine has been developed that provides a transformer supported by a carriage at a portion of the carriage located laterally outside another portion that supports both structures fixed to the carriage and provided with clamps. The portion of the carriage that supports the two structures is defined by a first beam and a second beam of the carriage parallel to the feed direction of the metal product.

[0011] In this solution, two upset cylinders are placed parallel to each other on a horizontal plane. The first upset cylinder is placed below the shoulders of the two structures, i.e., below the lower inclined surfaces. In contrast, the second upset cylinder is substantially placed at the feet of the two inclined structures on the side opposite to the side where the first cylinder is arranged.

[0012] While this solution enables upper access to some internal parts of the machine that can be accessed and lifted from above by an overhead crane and thus facilitates maintenance, on the other hand, the clamps are the most worn parts of the machine, requiring maintenance and manual replacement by the operator, and since the operator has to enter the machine, the maintenance of the clamps remains not easy, which is a disadvantage.

[0013] In fact, to access the clamp maintenance area, the operator comes in front of a second upset cylinder located at the feet of two inclined structures. This second upset cylinder occupies an area that is completely or at least partially below the lower clamp. Therefore, in order to obtain a space that allows comfortable access to the clamp maintenance area, the disassembly of the second upset cylinder is necessary.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0015] Therefore, there is a felt need to solve at least the above-mentioned drawbacks by providing a welding machine that can make clamp maintenance easier by facilitating access to the working space for maintenance.

[0016] An object of the present invention is to enable easy lateral access to the clamp maintenance area while minimizing the need for disassembly, reassembly, and alignment of parts, thereby enabling rapid maintenance and cleaning, and at the same time, being able to operate to remove heavy parts from the clamp holder structure using common aids such as cranes and overhead cranes. Preferably, it is to make a flash welding type welding machine.

[0017] Another object of the present invention is to make a welding machine that is simple from a structural point of view and yet capable of performing the necessary operations of known welding machines.

[0018] A further object of the present invention is to make a welding machine that can improve the safety of the operator.

Means for Solving the Problems

[0019] The present invention achieves at least one of such objects and other objects that will be apparent by referring to this specification, and is a welding machine, preferably a flash welding type, for welding the end of a first long metal product and the tip of a second long metal product along the feed direction X of the long metal product, The welding machine includes a carriage adapted to slide along the feed direction X, The carriage is, - a first structure connected to the carriage, - a first clamping means provided on the first structure for clamping the end of the first metal product or the tip of the second metal product, - a second structure slidable parallel to the feed direction with respect to both the first structure and the carriage, - a second clamping means provided on the second structure for clamping the tip of the second metal product or the end of the first metal product, - at least one transformer provided with conductors connected to the first clamping means and the second clamping means respectively for supplying current to the end and the tip, and is supported by, The first structure and the second structure are supported in a first part of the carriage defined by a first beam and a second beam of the carriage parallel to the feed direction X, and at least one transformer is fixed to the carriage and supported in a second part of the carriage located laterally outside the first part, The first structure and the second structure define respective longitudinal axes Z, Z' inclined at a first acute angle with respect to the horizontal plane, Two upset cylinders are provided parallel to the feed direction X for moving the second structure towards or away from the first structure along the feed direction X, The axes of the two upset cylinders are located along a plane Y passing through the passage region of the long metal product along the feed direction X, and the passage region is defined by the first clamping means and the second clamping means, The first upset cylinder is at least partially disposed under the first side of the first and second structures on one side of the passage region, and the second upset cylinder is substantially disposed on the feet of the second side opposite to the first side of the first and second structures on the other side of the passage region. In a welding machine, the plane Y is inclined by a second acute angle that is smaller than the first acute angle and different from zero with respect to the horizontal plane. Characterized by a welding machine.

[0020] In order to appropriately distribute the upset force without applying force to the structure, it is preferable that the plane Y includes the longitudinal central axis of the passage region of the long metal product along the feed direction X, and the passage region is defined by the lower clamping means and the upper clamping means at the metal product clamping position. This longitudinal passage region will be occupied by the metal product in the welding region. Therefore, it is preferable that the lower clamping means occupies a fixed position and the upper clamping means is adjustable along the respective longitudinal axes Z, Z' of the corresponding structures.

[0021] A further advantage is given by the fact that the maintenance of the lower upset cylinder, which is similarly possible, is easier. In fact, the new position of the lower upset cylinder makes its removal easier.

[0022] Furthermore, the new position of the upset cylinder makes it possible to install a larger spark confinement device that is more effective in protecting the machine and the operator.

[0023] Further features and advantages of the present specification will become clearer with reference to the detailed description of non-exclusive exemplary embodiments.

[0024] The dependent claims describe specific embodiments of the present invention.

[0025] In the description of the present invention, reference is made to the accompanying drawings, which are provided as non-limiting examples.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 2a

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0027] The same reference numerals and letters in the drawings identify the same elements or parts.

[0028] With reference to the drawings, some examples of a flash welding type welding machine according to the present invention are illustrated.

[0029] In all embodiments of the present invention, a welding machine suitable for welding the end of a first long metal product along the feed direction X of the long metal product to the tip of a second long metal product includes a carriage 1 adapted to slide along the feed direction X on a roller table (not shown) on which a long metal product such as a billet, bloom or bar advances.

[0030] The carriage 1 includes - a first structure 2 connected to the carriage 1, - first clamping means 3, 4 provided on the first structure 2 for clamping the end of the first metal product or the tip of the second metal product, - a second structure 5 slidable parallel to the feed direction X with respect to both the first structure 2 and the carriage 1, - Second clamping means 6, 7 provided on the second structure 5 for clamping the tip of the second metal product or the end of the first metal product; - At least one transformer 36 provided with conductors 37, 38, 39, 40 (Figs. 2 and 3) connected to the first clamping means 3, 4 and the second clamping means 6, 7 respectively for supplying current to the end and the tip; which supports them (Fig. 1).

[0031] The first structure 2 defines a longitudinal axis Z (Figs. 1 and 3) which is inclined with respect to the horizontal plane by a first acute angle, preferably between 40° and 70°, for example 45°. The second structure 5 defines its own longitudinal axis Z' (Figs. 1 and 2) parallel to the longitudinal axis Z and is spaced parallel to the first structure 2 along the feed direction X of the products to be welded.

[0032] In particular, the first clamping means 3, 4 of the first structure 2 include an upper clamp 3 and a lower clamp 4. Each clamp 3, 4 can be moved along the axis Z by respective movement systems provided on the structure 2.

[0033] The second clamping means 6, 7 of the second structure 5 include an upper clamp 6 and a lower clamp 7. Similarly in this case, each clamp 6, 7 can be moved along the axis Z' by respective movement systems provided on the structure 5.

[0034] Such movement systems include, for example, hydraulic cylinders or jacks or electric actuators, or mechanical movement devices such as cams or eccentrics.

[0035] It is advantageous in that it eliminates the need to tilt or slightly rotate the two structures 2, 5 in order to prevent a metal product such as a billet from being dragged on the lower clamp which is fixed in known machines of the prior art, by the movement and thus the adjustability of all the clamps of the clamping means.

[0036] In an alternative modification, only the upper clamp 3 is movable along the axis Z, and the lower clamp 4 is in a fixed position. Similarly, only the upper clamp 6 is movable along the axis Z', and the lower clamp 7 is in a fixed position.

[0037] The welding machine of the present invention provides adjustment means, and the adjustment means is for moving the second structure 5 so as to approach or move away from the first structure 2 along the feed direction X, and is placed parallel to the feed direction X. It includes, or consists of, two upset cylinders 23, 24 (Figs. 2 and 3). In particular, when two products are flash welded, an approach occurs.

[0038] The upset cylinders 23, 24 are axially placed on the first structure 2 at the first end and on the second structure 5 at the second end by respective pins.

[0039] The two upset cylinders 23, 24 are placed along a plane Y defined by the longitudinal axes of the two upset cylinders 23, 24 and passing through the passing region of the long metal product along the feed direction X (Figs. 2, 2a). This passing region is defined by the upper clamps 3, 6 and the lower clamps 4, 7.

[0040] In the illustrated modification, the first upset cylinder 23 is at least partially placed under the first side of the first structure 2 and the second structure 5 on one side with respect to the passing region, and the second upset cylinder 24 is on the other side with respect to the passing region. It is substantially placed on the foot of the second side opposite to the first side of the first structure 2 and the second structure 5.

[0041] Advantageously, the plane Y is inclined with respect to the horizontal plane by a second acute angle that is smaller than the first acute angle and different from zero. This configuration enables easy access from the lateral direction along the direction crossing the feed direction X to the clamp maintenance area, and enables rapid maintenance and cleaning. Preferably, the second acute angle is 30° or less.

[0042] In a modified example of the present invention, the first upset cylinder 23 is placed at a height higher than that of the second upset cylinder 24.

[0043] In a preferred modified example, the lower tightening means 4, 7 of the first tightening means 3, 4 and the second tightening means 6, 7 occupy fixed positions, and the upper tightening means 3, 6 are adjustable along the respective longitudinal axes Z, Z' of the corresponding structures 2, 5. The upper horizontal plane W which is the tangent plane of the second upset cylinder 24 is located above the upper ends 19 of the lower tightening means 4, 7. However, the distance between the upper horizontal plane W and the upper ends 19 of the lower tightening means 4, 7 is less than 20 mm, preferably less than 15 mm, and is included, for example, in the range of 8 to 12 mm.

[0044] Preferably, the lower tightening means 4, 7 define a horizontal plane 25 for placing metal products, and the distance between the upper horizontal plane W and the horizontal plane 25 is within the range of 100 to 150 mm, preferably 110 to 140 mm, according to the size of a welded metal product having a polygonal cross-section, for example, a square cross-section, such as a billet, bar or bloom. For example, a billet or bloom having variable sides within the range of 100 to 250 mm can be welded using the machine of the present invention. The distance between the upper horizontal plane W and the horizontal plane 25 is maximum for a product having a side of 250 mm and minimum for a product having a side of 100 mm.

[0045] With the above configuration, it is possible to install a removable walking passage 20 above the second upset cylinder 24 and near the lower tightening means 4, 7, making it easier for the operator to access the lower tightening means 4, 7.

[0046] In particular, the walking passage 20 may be arranged above the frame 50 (Fig. 2a) in which the second upset cylinder 24 is accommodated. Preferably, the distance between the upper surface of the frame 50 and the upper ends 19 of the lower tightening means 4, 7 is less than 70 mm, preferably less than 50 mm.

[0047] At least one step 21 may be provided between the walking passage 20 and the lower clamping means 4, 7 in order to enable the operator to approach the clamp more easily and to access the clamp maintenance area without the volume of the lower upset cylinder 24. The step 21 is placed at a height lower than that of the walking passage 20.

[0048] In a preferred specific example, the longitudinal central axis of the longitudinal passing region of the metal product along the feed direction X is on the plane Y, and the passing region is defined by the lower clamping means 4, 7 and the upper clamping means 3, 6 at the clamping position of the metal product, and thus is occupied by the metal product in the welding region.

[0049] Also in this example, it is preferable that the lower clamping means 4, 7 occupy fixed positions and the upper clamping means 3, 6 are adjustable along the respective longitudinal axes Z, Z' of the corresponding structures.

[0050] In particular, in order to ensure that the longitudinal central axis of the passing region of the metal product remains fixed on the plane Y and is always on the plane Y even when the size of the metal product changes, it may be sufficient to use pads having different sizes, and thus different thicknesses, for at least the lower clamping means 4, 7 according to the size of the product to be welded.

[0051] Thus, advantageously, the size, in particular the thickness, of the pads attached to the clamping means, preferably the lower clamping means 4, 7, is such that the longitudinal central axis of the passing region of the long metal product is always on the plane Y.

[0052] Thus, when it is necessary to change the size of the product to be welded, - the operator accesses the area of the clamping means laterally - removes the pads from at least the lower clamping means 4, 7 - attaches new pads to at least the lower clamping means 4, 7 The operation is performed.

[0053] In a further modification of the present invention (not shown), the second upset cylinder 24 is located completely below the lower clamping means 4, 7 of the first clamping means 3, 4 and the second clamping means 6, 7, i.e., completely below the lower end of the lower clamp. In this example, the step 21 need not be provided, and the walking passage 20 may be provided.

[0054] Optionally, the walking surface for the operator includes a walking passage 20 arranged parallel to the feed direction X and two additional walking passages 22 arranged perpendicular to the walking passage 20 at the ends of the walking passage 20, defining a substantially U-shaped walking surface, enabling the operator to move laterally with respect to the two structures 2 and 5.

[0055] Optionally, at least one feed guide 17 and at least one discharge guide 18 are provided for the feeding and discharging of metal products to / from the welding machine, each guide being constrained to the respective structures 2, 5 along the feed axis X. Alternatively, the guides may be part of the carriage 1. If provided, the guides 17, 18 may be placed below the respective walking passages 22.

[0056] In the first embodiment of the present invention, the first structure 2 and the second structure 5 are supported in a first portion 10 of the carriage 1 defined by a first beam 9 and a second beam 8 of the carriage, parallel to each other and to the feed direction X, and possibly included within the first portion 10. At least one transformer 36 is fixed to the carriage 1 and is supported in a second portion 11 of the carriage 1 located laterally outside the first portion 10, and possibly completely included within the second portion 11. The first upset cylinder 23 is placed in the first portion 10 of the carriage at a position between at least one transformer 36 and the structures 2, 5, and thus at a position between the second portion 11 of the carriage and the structures 2 and 5.

[0057] The transformer 36 may be a single transformer. Alternatively, a group of transformers that supply electricity in cooperation with the clamps 3, 4, 6, and 7 by means of the conductors 37, 38, 39, and 40 may be provided.

[0058] In a modification (not shown) of this first embodiment, for example, two or more transformers are provided that are fixed to the carriage 1, supported in the second portion 11, and possibly completely contained within the second portion 11.

[0059] In this first embodiment of the present invention, the second portion 11 of the carriage 1 may preferably be defined by the second beam 8 and the third beam 14 of the carriage 1 that are parallel to the second beam 8. The first beam 9 and the third beam 14 are outer peripheral beams of the carriage 1, and the second beam 8 is an intermediate beam. At least two additional outer peripheral beams that cross, preferably are perpendicular to, the beams 9, 8, 14 may be provided to define the outer periphery of the carriage 1 together with the beams 9 and 14.

[0060] The carriage 1 is preferably placed on two sliding guides 15, 16 that are fixed directly or by a frame to the floor under the welding machine, and the sliding guides are parallel to each other and to the axis X. In the modification shown in FIGS. 1 to 3, the first beam 9 and the second beam 8 of the carriage 1 are located at the respective sliding guides 16, 15. In this case, the first portion 10 of the carriage 1 is above and within the region defined by the sliding guides 15, 16.

[0061] Alternatively, the beams 9, 8 may be offset with respect to the sliding guides 16, 15.

[0062] Optionally, the conductors 37, 38 and the conductors 39, 40 pass under the first structure 2 and the second structure 5 respectively to connect the transformer 36 to the first clamping means 3, 4 and the second clamping means 6, 7, and have a space between the first clamping means 3, 4 and a space between the second clamping means 6, 7 that are freely accessible from above and below in the absence of a long metal product to be welded.

[0063] Since the transformer 36 is not arranged on the structures 2 and 5, it is advantageous that when there is no long metal product to be welded, the space between the first clamping means 3, 4 and the space between the second clamping means 6, 7 are freely accessible from both above and below.

[0064] For a modification (not shown) in which two or more transformers are provided in the second part 11 of the trolley 1, such as when only two transformers are arranged one above the other, the first upper conductor and the first lower conductor come out from their respective transformers and reach the clamps 3, 4 of the first structure 2 respectively, and the second upper conductor and the second lower conductor come out from their respective transformers and reach the clamps 6, 7 of the second structure 5 respectively.

[0065] In all modifications, the current paths are each closed between the upper clamps 3 and 6 and between the lower clamps 4 and 7.

[0066] In addition to being placed substantially parallel to each other, the first structure 2 and the second structure 5 are preferably placed across both the first beam 9 and the second beam 8, preferably orthogonally to both the first beam 9 and the second beam 8.

[0067] In particular, in the first modification, the first beam 9 and the second beam 8 have a first part each that is close to the first structure 2 and to which the first structure 2 is integrally fixed, and a second part each that is away from the first structure 2 and to which the second structure 5 is slidably connected.

[0068] In a modification of the present invention, the second part of the first beam 9 is inserted into a first through hole (FIG. 1) of the second structure 5 in which a first roller or pad 12 for the sliding of the second structure 5 on the first beam 9 is provided inside, and the second part of the second beam 8 is inserted into a second through hole of the second structure 5 in which a second roller or pad 13 (FIG. 1) for the sliding of the second structure 5 on the second beam 8 is provided inside.

[0069] For example, if it is necessary or desirable to slightly move two structures 2 and 5 to prevent a metal product such as a billet from being dragged on the lower clamp, in a second variant (not shown), the first structure 2 and the second structure 5 are not supported on the carriage 1 by the beams 8 and 9 of the carriage themselves, but are supported at a first portion 10 of the carriage 1 by a lifting system adapted to lift the first structure 2 and the second structure 5 together relative to the carriage 1 by rotation along a plane transverse to the feed direction X. Such rotation can be in the range of 1° to 25°, for example 1° to 15°. Thus, this lifting system makes it possible to move the structures 2 and 5 relative to the product to be welded.

[0070] Preferably, the lifting system is of a link type.

[0071] A further advantage of the present invention may be to provide at least one motor 31 connected to a gear 32 adapted to engage a rack 33 (Figure 2) provided on at least one of the sliding guides 15, 16, preferably on one side of the sliding guide 15, on the carriage 1.

[0072] A second embodiment of the welding machine of the present invention is shown in Figure 4. The above description of the first embodiment also applies to this second embodiment. The second embodiment is - a first transformer 36, which is fixed to the carriage 1 and is supported at a second portion 11 of the carriage 1 located laterally outside the first portion 10 defined by the first beam 9 and the second beam 8, and may possibly be completely contained within the second portion 11, - a second transformer 36', which is fixed to the carriage 1 and is supported at a third portion 11' of the carriage 1 on the opposite side of the second portion 11 located laterally outside the first portion 10, and may possibly be contained within the third portion 11', is different from the first embodiment in that it is provided with.

[0073] The first part 10 of the carriage 1 is defined by the first beam 9 and the second beam 8 of the carriage 1 parallel to the feed direction X.

[0074] The second part 11 of the carriage 1 is defined by the second beam 8 and the third beam 14 of the carriage 1 preferably parallel to the second beam 8.

[0075] The third part 11' of the carriage 1 is defined by the first beam 9 and the fourth beam 14' preferably parallel to the first beam 9.

[0076] The fourth beam 14' and the third beam 14 are outer peripheral beams of the carriage 1, and the first beam 9 and the second beam 8 are intermediate beams of the carriage.

[0077] At least two additional outer peripheral beams crossing the beams 14', 9, 8, 14, preferably perpendicular to the beams 14', 9, 8, 14, are provided to define the outer periphery of the carriage 1 together with the beams 14' and 14.

[0078] In this second embodiment, the upper conductor and the lower conductor exit from the first transformer 36 and reach the upper clamps 3 and 6 of the structures 2 and 5 respectively, and the upper conductor and the lower conductor exit from the second transformer 36' and reach the lower clamps 4 and 7 of the structures 2 and 5 respectively. Also in this case, the current paths are closed between the upper clamps 3 and 6 and between the lower clamps 4 and 7 respectively.

Claims

1. A welding machine, preferably a flash welding type, for welding the end of a first long metal product along the feed direction X of the long metal product to the tip of a second long metal product, the welding machine comprising a carriage (1) adapted to slide along the feed direction X, wherein the carriage (1) is provided with: - a first structure (2) connected to the carriage (1); - first clamping means (3, 4) provided on the first structure (2) for clamping the end of the first metal product or the tip of the second metal product; - a second structure (5) slidable parallel to the feed direction with respect to both the first structure (2) and the carriage (1); - second clamping means (6, 7) provided on the second structure (5) for clamping the tip of the second metal product or the end of the first metal product; - at least one transformer (36) provided with conductors connected to the first clamping means (3, 4) and the second clamping means (6, 7) respectively for supplying current to the end and the tip; and supporting; the first structure (2) and the second structure (5) are supported in a first part (10) of the carriage (1) defined by a first beam (9) and a second beam (8) of the carriage (1) parallel to the feed direction (X), the at least one transformer (36) is fixed to the carriage (1) and supported in a second part (11) of the carriage (1) located laterally outside the first part (10); the first structure (2) and the second structure (5) define respective longitudinal axes (Z, Z') inclined at a first acute angle with respect to the horizontal plane; two upset cylinders (23, 24) are provided parallel to the feed direction X for moving the second structure (5) towards or away from the first structure (2) along the feed direction X; the axes of the two upset cylinders (23, 24) define a plane Y passing through the passing region of the long metal product along the feed direction X, the passing region being defined by the first clamping means (3, 4) and the second clamping means (6, 7); The first upset cylinder (23) is at least partially placed under the first side of the first structure (2) and the second structure (5) on one side with respect to the passage region, and the second upset cylinder (24) is substantially placed on the foot of the second side opposite to the first side of the first structure (2) and the second structure (5) on the other side with respect to the passage region. In a welding machine, the plane Y is inclined by a second acute angle that is smaller than the first acute angle and different from zero with respect to the horizontal plane. A welding machine characterized by this.

2. The welding machine according to claim 1, wherein the first upset cylinder (23) is placed at a height higher than that of the second upset cylinder (24).

3. The lower clamping means (4, 7) of the first clamping means (3, 4) and the second clamping means (6, 7) occupies a fixed position, and the upper horizontal plane (W) serving as the contact plane of the second upset cylinder (24) is located above the upper end (19) of the lower clamping means (4, 7), and the distance between the upper horizontal plane (W) and the upper end (19) is preferably smaller than 20 mm, more preferably smaller than 15 mm. The welding machine according to claim 1 or 2.

4. The lower clamping means (4, 7) defines a horizontal plane (25) for supporting the metal product, and the distance between the upper horizontal plane (W) and the horizontal plane (25) is in the range of 100 to 150 mm, preferably 110 to 140 mm. The welding machine according to claim 3.

5. The welding machine according to claim 1 or 2, wherein the second upset cylinder (24) is completely located below the lower clamping means (4, 7) of the first clamping means (3, 4) and the second clamping means (6, 7).

6. The lower clamping means (4, 7) of the first clamping means (3, 4) and the second clamping means (6, 7) occupy a fixed position, and the size, particularly the thickness, of the pads of the clamping means (3, 6, 4, 7), preferably the lower clamping means (4, 7), is such that the longitudinal central axis of the elongate metal product passing region along the feed direction X lies on the plane Y, and the passing region is defined by the lower clamping means (4, 7) and the upper clamping means (3, 6) at the metal product clamping position, the welding machine according to any one of claims 1 to 5.

7. A removable walkway (20) is provided above the second upset cylinder (24) and near the lower clamping means (4, 7), and preferably at least one step (21) is provided between the walkway (20) and the lower clamping means (4, 7). The welding machine according to claim 3 or 4 or 5 or 6.

8. The first acute angle is included within the range of 40° to 70°, and the second acute angle is 30° or less, the welding machine according to any one of claims 1 to 7.

9. Only one transformer (36) or two or more transformers are provided, which are fully supported in the second part (11) of the trolley (1), or at least two transformers are provided, and a first transformer (36) of the two transformers is fixed to the trolley (1) and supported in the second part (11) of the trolley (1), and a second transformer (36') of the two transformers is fixed to the trolley (1) and is supported in the third part (11') of the trolley (1) which is on the opposite side of the second part (11) and located laterally outside the first part (10), the welding machine according to any one of claims 1 to 8.

10. The second part (11) is preferably parallel to the feed direction (X) and is defined by the second beam (8) and the third beam (14) of the trolley (1), the welding machine according to claim 1 or 9.

11. When only one transformer (36) or two transformers are completely supported in the second portion (11), the first beam (9) and the third beam (14) are the outer peripheral beams of the carriage (1), and the second beam (8) is the intermediate beam. Or, when the first transformer (36) is supported in the second portion (11) and the second transformer (36') is supported in the third portion (11') of the carriage (1), the third portion (11') is defined by the first beam (9) and the fourth beam (14'), and the fourth beam (14') and the third beam (14) are the outer peripheral beams of the carriage (1), and the first beam (9) and the second beam (8) are the intermediate beams of the carriage. The welding machine according to claim 10.

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