Roll-formed tube manufacturing

Abstract

A seam guide assembly (1) configured to maintain longitudinal edges (101) of a metal strip (102) in position prior to welding the edges together in a welding section (201) of a welded pipe roll forming apparatus (200), comprising a front seam guide tip component (2), a through channel (6) provided in a holder (3), said channel having an inlet opening (7) located on a first side (5) of the holder and adjacent to the front seam guide tip component (2), and an outlet opening (8) located on a second side (9) of the holder, said outlet opening adapted to be connected to a vacuum source. a welded pipe roll-forming apparatus (200) including a seam guide assembly (1); a vacuum extraction section (205) configured to extract solid particles generated inside the pipe (100) during high frequency induction welding of the pipe edges, the vacuum extraction section (205) being positioned within the apparatus at a location where the rolled-formed pipe edges (101) have not yet been welded together; and a method of manufacturing a pipe, comprising: extracting solid particles generated inside the pipe (100) during high frequency induction welding by applying a vacuum to the section (205) of the pipe where the rolled-formed pipe edges (101) have not yet been welded together.

Description

[Technical Field]

[0001] The present disclosure relates to roll forming and the production of welded pipe, and more particularly to a seam guide assembly configured for use in a welded pipe roll forming apparatus, a roll forming apparatus including a seam guide assembly, and a method of producing pipe comprising aluminum or an alloy thereof by rolling strip in a welded pipe roll forming apparatus. [Background technology]

[0002] Welded pipes and tubes are typically manufactured by longitudinally forming a flat metal strip into a nearly complete tube and then welding two edges together. For example, there are many applications for roll-formed piping in the HVAC&R market (heating, ventilation, air conditioning, and refrigeration). In this technology field, environmental demands motivate developments toward more efficient air conditioning and refrigeration equipment. In response, efforts have been made to provide small-diameter copper tubes with various internal enhancements that can increase the heat transfer coefficient compared to standard smooth solutions. The use of advanced products, such as small-diameter welded tubes with internal patterning, requires the tubes to meet strict requirements in terms of internal contamination levels. With increasing demands for cost reduction, there is interest in providing an alternative to the traditionally dominant copper piping for use in air conditioning and refrigeration equipment, in the form of aluminum piping. However, it has proven difficult to manufacture aluminum tubes with competitive properties for each application, such as in the HVAC&R field. Summary of the Invention [Means for solving the problem]

[0003] The present disclosure relates to tools and methods for manufacturing welded pipe that provide efficient production of advanced pipe products formed from aluminum or its alloys. According to the present disclosure, a seam guide assembly is provided that is configured to maintain the longitudinal edges of a metal strip being rolled into a tubular shape in a predetermined position before the edges are welded together in a welding section of a welded pipe roll-forming apparatus. The seam guide assembly includes a front seam guide tip component mounted to a holder with an elongated tip extending from a first side of the holder, the tip configured to be inserted between the pipe edges to be welded. A through channel is provided in the holder, the channel having an inlet opening located on the first side of the holder and adjacent the front seam guide tip component longitudinally of the holder, and an outlet opening configured to be connected to a vacuum source by a connection fitting, such as a threaded or bayonet coupling, to which a suitable connection component can be connected. The seam guide assembly preferably includes a rear seam guide tip component attached to the holder such that its elongated tip protrudes from a first side of the holder. The rear seam guide tip component is positioned on the holder longitudinally away from the front seam guide tip component, with the channel inlet opening located between the front and rear tip components. Thus, the seam guide tip is divided into two sections, with the channel inlet opening located between them. The channel inlet opening preferably does not exceed the outer diameter of the tube and more preferably has a width approximately corresponding to the distance between the edges of the generally tubular shaped strip. The channel inlet opening preferably has an elongated shape oriented in the longitudinal direction of the holder to fit the opening between the strip edges to be welded. The holder may preferably include guide flanges located on each side of the channel inlet opening.

[0004] The present disclosure also provides a welded pipe roll-forming apparatus including a roll-forming section configured to form a metal strip into a tubular shape, followed by a welding section. The welding section includes a seam guide assembly, a high-frequency induction welding coil, and a pair of welding rollers, and is configured to weld together the longitudinal edges of the metal strip being rolled into a tubular shape while the tubing is advanced through the apparatus in a direction of travel. The apparatus further includes a vacuum extraction section configured to extract solid particles generated inside the tubing during high-frequency induction welding of the tubing edges, the vacuum extraction section being positioned on the apparatus at a location where the edges of the rolled tubing have not yet been welded together. The vacuum extraction section may preferably include the aforementioned seam guide assembly disposed between the welding coil and the roll-forming section. The vacuum extraction section may advantageously include a gap vacuum nozzle configured to be connected to a vacuum source and disposed rearward of the seam guide assembly in the direction of travel of the tubing, the gap vacuum nozzle configured to extract solid particles through an opening between the unwelded edges of the tubing. The vacuum extraction section may further comprise a tube vacuum nozzle configured to be connected to a vacuum source and positioned rearward of the seam guide assembly in the direction of tube travel, the tube vacuum nozzle configured to be positioned within the roll-formed, yet unwelded tube to extract solid particles present within the tube.

[0005] The apparatus may further advantageously include a backflushing device comprising a tubular member having a gas valve attached to its outlet end and a coupling attached to its inlet end, the coupling configured to be connected to a pressurized gas source. The backflushing device is configured to apply a gas flow in a direction opposite to the tube travel direction at a position before the welding coil in the tube travel direction, pushing any remaining solid particles in a direction opposite to the direction of travel of the tube being formed, thereby allowing them to be extracted by the vacuum section. The gas may preferably be a reverse flow nozzle. The tubular member of the backflushing device may include a straight first section having a front end to which the reverse flow nozzle is attached, the straight section having a length greater than the distance from the rear end of the seam guide assembly to a position before the welding coil in the tube travel direction. The straight first section has an outer diameter smaller than the inner diameter of the tube to be welded, so that it can be inserted into the finished tube. The tubular member may further include a second section having a rear end carrying the coupling. The second section may be angled relative to the first section. The backflushing device is preferably arranged within the apparatus so that the metal strip is rolled around the straight first section of the tubular member and the backflushing nozzle is positioned in front of the welding coil in the direction of travel of the tube.

[0006] The present disclosure further relates to a tube produced by the above-described apparatus, wherein the metal strip comprises aluminum or an alloy thereof.

[0007] The present disclosure also provides a method for producing a tube comprising aluminum or an alloy thereof. The method includes rolling a strip comprising aluminum or an alloy thereof into a tube in a roll-forming section of a welded tube roll-forming apparatus and welding the tube edges together in a high-frequency induction welding section of the apparatus, the high-frequency induction welding section including a welding coil and a pair of welding rollers. The welding includes extracting solid particles generated inside the tube during high-frequency induction welding by applying a vacuum to a section of the tube where the longitudinal edges of the metal strip being rolled into the tube have not yet been welded together. The method may also include backflushing the solid particles by applying pressurized gas in a direction opposite to the direction of tube travel, preferably at a location ahead of the welding coil in the direction of tube travel.

[0008] The detailed description and specific examples given below disclose preferred embodiments of the present disclosure by way of example only. Those skilled in the art will understand based on the detailed description that changes and modifications can be made within the scope of the present disclosure. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a forming and welding apparatus. [Figure 2] FIG. 1 is a schematic diagram of a high frequency welding setup. [Figure 3] FIG. 1 is a schematic diagram showing the location of the vacuum extraction section in the forming and welding apparatus. [Figure 4] FIG. 1 is a perspective view of a welding section of a forming and welding apparatus including a seam guide assembly. [Figure 5] 3 is a cross-sectional view of the seam guide assembly in the longitudinal direction of the seam guide assembly. FIG. [Figure 6a] FIG. 10 is a view showing the seam guide assembly from the tip end side of the seam guide. [Figure 6b] 1A and 1B show the components of a seam guide assembly. [Figure 7a] FIG. 1 shows a backflushing device. [Figure 7b]FIG. 1 shows a gas valve of a backflushing device. [Figure 8] FIG. 1 is a schematic diagram of a portion of the forming and welding apparatus showing the location of the tube vacuum nozzle and the gap vacuum nozzle. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present disclosure relates to tools and methods for manufacturing tubes that enable the production of advanced small diameter aluminum tube products having diameters of 20 mm or less, preferably 5-10 mm. The tube products are preferably manufactured as continuous tube coils having lengths greater than 500 m, preferably greater than 1000 m. Such tube products are used, for example, in the fields of heating, ventilation, air conditioning, or refrigeration.

[0011] The welded pipe roll forming process involves rolling a strip into a tubular shape, welding the strip's longitudinal edges together, and then high-frequency welding the resulting tube with an induction-heated welding coil. To achieve this, the strip is fed into a forming mill or apparatus, which shapes the strip through various successive forming steps, each performed by the same number of forming rolls as there are steps, as shown diagrammatically in Figure 1. As the strip passes through the welding coil, an electromagnetic field is induced around the welding coil, which induces a current that flows through the strip and is concentrated approximately at the edges to be joined. The resistance of the metal to the current generates the necessary heat at these edges, causing them to rapidly reach their melting point. While still in a molten state, the edges are pressed together by interaction with side squeeze rolls, which apply force to the strip, thus creating the required pressure at the interface between the two edges. As the strip passes through the welding rolls, the oxidized and molten metal are forced out of the joint, joining the underlying clean metal. After welding, roll sizing completes the process, giving the tube its desired final shape.

[0012] In radio frequency welding, current flowing through a work coil generates a magnetic field that intersects with the open tube being approximately formed. The use of high frequency alternating current results in two important physical phenomena: the "skin effect," which describes the tendency of induced radio frequency currents to flow in the shallow skin of a conductor, and the "proximity effect," which describes the tendency of the proximity of two conductors through which an induced current flows to concentrate the current on opposing surfaces of the conductors. Due to the skin and proximity effects, the induced current concentrates in the "V," i.e., the V-shaped space formed between the longitudinal strip edges just before the weld point, and in the edge "skin" volume, i.e., the outside of the strip in the area located within the welding coil. Figure 2 shows a schematic diagram of a radio frequency welding setup.

[0013] In the production of aluminum tubes by high-frequency welding, the presence of electromagnetic forces applied to the liquid phase at the apex of the V where the strip edges meet causes the emission of solid particles, i.e., atomization of aluminum particles. This solid particle emission is sprayed in all directions from the weld point, meaning that it also reaches the interior of the welded tube. As the tube moves at high speed through the manufacturing equipment, solid contaminant particles move with the tube through openings between the unwelded strip edges.

[0014] The manufacture and use of advanced products, such as small-diameter welded aluminum pipe with internal patterning, requires strict requirements for internal contamination levels for the pipe, with cleanliness limits typically set at less than 0.5 mg / ft of solid particle internal contamination. However, high-frequency welding of small-diameter aluminum pipe (having a diameter of 10 mm or less) results in solid particle contamination levels that can typically be 25 to 100 times higher than acceptable levels in the final pipe product. This presents a problem when manufacturing significant lengths of small-diameter piping because it is difficult to flush these particles from the finished pipe. Avoiding the presence of contaminants, for example in the form of particles, in the final pipe product is important to ensure adequate flow characteristics within the pipe when installed in, for example, heating, ventilation, air conditioning, or refrigeration equipment. Therefore, the present disclosure aims to provide a solution that facilitates the manufacture of roll-formed welded aluminum piping. This solution relies on the removal of internal solid particle contamination, performed inline during the manufacture of the welded pipe by vacuum extraction. This can improve the product quality of the resulting pipe product, thereby enabling the manufacture of advanced small-diameter pipe from aluminum or its alloys.

[0015] Thus, a seam guide assembly is provided that can be used in a welded pipe forming apparatus to enable solid particle emissions generated inside the welded pipe by high-frequency welding to be removed by applying a vacuum. The seam guide is positioned immediately before the welding coil in the direction of tube travel (T) and is provided to guide the weld seam and prevent sliver formation at the strip edges, avoiding seam rolling and providing good electrical insulation before the welding coil. Thus, the seam guide assembly is configured to maintain the longitudinal edges of a metal strip being rolled into a tube in a predetermined position before the edges are welded together in the welding section of the welded pipe roll forming apparatus. The seam guide assembly includes a forward seam guide tip component attached to a holder such that an elongated tip protrudes from a first side of the holder in a direction away from the first side, the tip configured to be inserted between the pipe edges to be welded.

[0016] The holder may typically have a generally elongated shape suitable for positioning along a pipe, with the first side being the side of the holder intended to face the pipe to be welded during the welding process. During the welding process, the longitudinal pipe edges are pressed against the side of the tip as they are squeezed toward each other by the squeeze rolls, and are thereby held in place by the tip of the seam guide assembly, assisted by the squeeze rolls. The forward seam guide tip component may extend from the holder in the longitudinal direction of the holder, allowing its outermost tip edge to extend further forward along the pipe than would be possible for the holder due to lack of space. The holder is provided with a through channel. The channel has an inlet opening located on the first side of the holder, i.e., the side facing the pipe to be welded, and an outlet opening located on the second side of the holder, i.e., the side of the holder not facing the pipe, for example, perpendicular to the first side or opposite the first side.

[0017] The through channel has an inlet opening positioned adjacent to the forward seam guide tip component in the longitudinal direction of the holder, and an outlet opening configured to be connected to a vacuum source that allows particles sprayed onto the interior of the tube by high frequency welding to be removed from the interior of the formed and welded tube through the channel of the seam guide assembly. A connector can be attached to the outlet opening to facilitate connection to the vacuum source.

[0018] The seam guide assembly preferably includes a rear seam guide tip component attached to the holder such that its elongated tip protrudes from a first side of the holder. The rear seam guide tip component is positioned on the holder longitudinally away from the front seam guide tip component, with the channel inlet opening located between the front and rear tip components. The seam guide tip is thus divided into two sections, with the channel inlet opening located between them. This allows the strip edges to be welded to be properly guided along the greater length of the rolled strip. The holder of the seam guide assembly may preferably be formed from brass, and the seam guide tip component is preferably formed from an electrically insulating material, preferably a ceramic material. The channel inlet opening preferably does not exceed the outer diameter of the tube, and more preferably has a width that corresponds approximately to the distance between the edges of the strip formed into a generally tubular shape. This allows the vacuum applied through the channel to effectively act on the interior of the rolled strip. The channel entrance opening preferably has an elongated shape oriented in the longitudinal direction of the holder to fit the opening between the strip edges to be welded. To facilitate accurate positioning of the seam guide, the holder preferably includes guide flanges located on each side of the channel entrance opening. The seam guide assembly does not include any components that must move within the pipe during the welding process. This allows for the welding of very small diameter pipes, such as 20 mm or less, preferably 5-10 mm.

[0019] The present disclosure also provides a welded tube roll-forming apparatus including a roll-forming section configured to form a metal strip into a tubular shape, followed by a welding section. The welding section includes a seam guide assembly, a high-frequency induction welding coil, and a pair of welding rollers configured to weld together the longitudinal edges of the metal strip being rolled into a tubular shape while the tubing is advanced through the apparatus in a travel direction. The welding coil is typically a copper tube bent to create multiple windings perpendicular to the tubular direction.

[0020] The apparatus further includes a vacuum extraction section configured to extract solid particles generated within the tube during high-frequency induction welding of the strip edges. The vacuum extraction section is located within the apparatus at a position where the edges of the roll-formed strip have not yet been welded together, i.e., after the welding section (201), i.e., upstream of the welding section in the direction of tube travel. The vacuum extraction section is preferably positioned within the apparatus so as to cover the gap between the unwelded strip edges adjacent to the welding coil. The vacuum reduction should be selected to sufficiently remove particles present within the tube, e.g., a pulling force of approximately 10 m / s or more for a vacuum pipe with a diameter of 2 to 5 cm.

[0021] The vacuum extraction section may preferably include the aforementioned seam guide assembly, located between the welding coil and the roll-forming section, preferably as close as possible to the welding coil. The vacuum extraction section may advantageously include a gap vacuum nozzle, configured to be connected to a vacuum source and located behind the seam guide assembly in the direction of tube travel, configured to extract solid particles through an opening between the not-yet-welded edges of the tube. The gap vacuum nozzle may preferably be positioned over the opening between the edges of the generally tubular strip, have a width no greater than the outer diameter of the tube and greater than the distance between the edges, and cover all or part of the length of the generally tubular strip contained between the tube roll-forming section and the seam guide tip assembly of the apparatus. The vacuum extraction section may further include a tube vacuum nozzle, configured to be connected to a vacuum source and located behind, i.e., upstream of, the seam guide assembly in the direction of tube travel, configured to be positioned within the roll-formed, not-yet-welded tube to extract solid particles present within the tube. In this way, internal particle contamination can be further reduced.

[0022] As mentioned above, cleaning small-diameter pipes having a considerable length is difficult. However, according to the present disclosure, the apparatus can advantageously include a backflushing device to further improve the removal of any particles within the finished pipe. The backflushing device includes a tubular member having a gas valve attached to its outlet end and a coupling attached to its inlet end, the coupling configured to be connected to a pressurized gas source, preferably a neutral gas such as nitrogen gas. The backflushing device is configured to apply a gas flow in a direction opposite to the tube travel direction at a position before the welding coil in the tube travel direction, pushing any remaining solid particles in a direction opposite to the travel direction of the tube being formed, thereby allowing those particles to be extracted in the vacuum section, thereby further facilitating the removal of particles within the welded pipe that still remain after the weld point, i.e., downstream of the weld point, preferably downstream of the squeeze roll, which may also be part of the welding section. Therefore, backflushing of gas from a position inside the pipe beyond the forging point ultimately improves vacuum efficiency and bubble removal.

[0023] The gas valve may suitably be a reverse flow nozzle. The tubular member may be a flexible pipe made of a heat-resistant material such as PTFE. The tubular member of the backflushing device may include a straight first section having a front end to which the reverse flow nozzle is attached, the straight section having a length greater than the distance from the rear end of the seam guide assembly to a position in front of the welding coil in the direction of tube travel. The straight first section has an outer diameter smaller than the inner diameter of the tube to be welded, so that it can be inserted into the finished tube. The tubular member may further include a second section having a rear end carrying a coupling. The second section may be angled relative to the first section. The backflushing device is preferably positioned within the apparatus so that the metal strip is rolled around the straight first section of the tubular member and the reverse flow nozzle is positioned in front of the welding coil in the direction of tube travel. The portion of the tubular member of the backflushing device closest to the induction coil can be made of glass-fiber-reinforced epoxy or ceramic material to withstand the high temperatures generated locally during welding and avoid damage from contact with solid particles. The gas valve may have an outer diameter smaller than the inner diameter of the pipe. Note that the backflushing device can be used independently in equipment for producing roll-formed and welded pipe, i.e., it does not necessarily require the presence of a vacuum device or seam guide assembly.

[0024] The present disclosure further relates to a tube produced by the above-described apparatus, wherein the metal strip comprises aluminum or an alloy thereof.

[0025] A method for producing a tube comprising aluminum or an alloy thereof is also provided. The method includes rolling a strip comprising aluminum or an alloy thereof into a tube in a roll-forming section of a welded tube roll-forming apparatus and welding the tube edges together in a high-frequency induction welding section of the apparatus, which includes a welding coil and a pair of welding rollers. The welding includes extracting solid particles generated inside the tube during high-frequency induction welding by applying a vacuum to a section of the tube where the longitudinal edges of the metal strip being rolled into the tube have not yet been welded together. The method may also include backflushing the solid particles by applying pressurized gas in a direction opposite to the direction of tube travel, preferably at a location ahead of the welding coil in the direction of tube travel. The strip from which the tube is formed preferably has an enhanced surface, obtained by embossing a pattern to enhance the heat transfer properties of the tube product. The strip width is selected so that the formed tube achieves a desired diameter, preferably 20 mm or less, preferably 5-10 mm.

[0026] Description of exemplary embodiments The tools and methods of the present disclosure will now be described with reference to the accompanying drawings, in which preferred exemplary embodiments of the present disclosure are shown. However, the present disclosure may be embodied in other forms and should not be construed as limited to the embodiments disclosed herein. The disclosed embodiments are provided so that the scope of the present disclosure will be fully conveyed to those skilled in the art.

[0027] 1 shows a schematic diagram of a conventional welded pipe roll forming apparatus 200 including a roll forming section 202 configured to form a metal strip into a tubular shape, followed by a welding section 201, a high frequency induction welding coil 203, and a pair of welding rollers 204. The apparatus does not include a seam guide assembly.

[0028] 2 shows a more detailed schematic of the radio frequency welding setup, with a metal strip 102 being approximately formed into a tube 100. The figure shows how the strip is formed so that the longitudinal edges abut each other, and how the approximately closed tube is moved through a welding coil.

[0029] 4 is a perspective view of a welding section of a forming and welding apparatus including a seam guide assembly of the present disclosure. FIG. 4 also shows how the backflushing device 300 is inserted into a substantially closed tube. The opening between the longitudinal side edges of the strip is somewhat exaggerated for illustrative purposes.

[0030] Figure 5 is a cross-sectional view of the seam guide assembly in the longitudinal direction of the seam guide assembly. The small arrows in Figure 5 indicate the path of travel of the solid particles to be extracted. Figure 6a shows the seam guide assembly from the seam guide tip side, and Figure 6b shows the components of the seam guide assembly.

[0031] The seam guide assembly 1 is configured to hold the longitudinal edges 101 of a metal strip 102 being rolled into a tube 100 in place before the edges are welded together in a welding section 201 of a welded tube roll forming apparatus 200. The seam guide assembly 1 includes a front seam guide tip component 2 mounted in a holder 3, with an elongated tip 4 extending from a first side 5 of the holder. The tip 4 is configured to be inserted between the tube edges 101 to be welded. The holder 3 is provided with a through channel 6. The channel has an inlet opening 7 located on the first side 5 of the holder, adjacent the front seam guide tip component 2 in the longitudinal direction of the holder, and an outlet opening 8 located on a second side 9 of the holder. The outlet opening is configured to be connected to a vacuum source. A connecting piece 18 can be coupled to the outlet opening, for example, by a screw thread. The rear seam guide tip component 10 is mounted in the holder 3 such that the elongated tip 11 extends from the first side 5 of the holder. The rear seam guide tip component 10 is positioned in the holder longitudinally away from the front seam guide tip component 2, and the channel entrance opening 7 is located between said front and rear tip components 2, 10. The holder 3 comprises guide flanges 12 arranged on each side of the channel entrance opening 7.

[0032] FIG. 3 schematically illustrates a welded tube roll-forming apparatus 200, including a roll-forming section 202 configured to form a metal strip 102 into a tube 100, followed by a seam guide assembly and / or vacuum extraction section 205, and a welding section 201 including a high-frequency induction welding coil 203 and a pair of welding rollers 204. The apparatus is configured to weld together the longitudinal edges 101 of the metal strip 102 being rolled into a tube 100 while the tube is advanced through the apparatus in a travel direction (T). FIG. 3 also illustrates the location of the vacuum extraction section 205 in the forming and welding apparatus. This figure shows how the vacuum extraction section, which can include both a seam guide and a vacuum application device, is positioned on a tube that has not yet been closed and welded. Details regarding the equipment are not shown and will be more clearly illustrated in the following figures. The high-frequency induction welding coil 203 can be variously designed, as shown, for example, in FIGS. 2-4 and 7a.

[0033] The apparatus further comprises a vacuum extraction section 205 configured to extract solid particles generated inside the tube 100 during high frequency induction welding of the tube edges, the vacuum extraction section 205 being positioned on the apparatus at a location on the roll-formed tube where the edges 101 have not yet been welded together. The vacuum extraction section 205 comprises a seam guide assembly 1 disposed between the welding coil 203 and the roll-forming section 202.

[0034] As shown schematically in FIG. 8 , the weld vacuum extraction section 205 of the tube roll forming apparatus can include a gap vacuum nozzle 206 and a tube vacuum nozzle 207. The arrows in the figure indicate the travel path of the solid particles to be extracted. The gap vacuum nozzle 206 is connected to a vacuum source and is positioned behind the seam guide assembly 208 in the direction of travel (T) of the tube 100 and is configured to extract solid particles through openings between the edges of the tube 100 that have not yet been welded. The tube vacuum nozzle 207 is also connected to a vacuum source and is positioned behind the seam guide assembly 208 in the direction of travel (T) of the tube 100. The tube vacuum nozzle 207 is positioned within the roll-formed, yet-to-be-welded tube to extract solid particles present within the tube.

[0035] FIG. 7a shows a backflushing device, and FIG. 7b shows its gas valve 302, which is in the form of a reverse flow nozzle. The backflushing device 300 comprises a tubular member 301 having a gas valve 302 attached to an outlet end 303 and a coupling 304 attached to an inlet end 305. The coupling is connected to a pressurized gas source, and the backflushing device applies a gas flow in a direction opposite to the direction of tube travel (T) at a position (P) before the welding coil 203 in the direction of tube travel (T). In the illustrated example, the tubular member 301 of the backflushing device 300 includes a straight first section 306 having a front end 303 to which the reverse flow nozzle 302 is attached. This straight section has a length L that exceeds the distance from the rear end 13 of the seam guide assembly 1 to a position (P) before the welding coil 203 in the direction of tube travel (T) (as seen, for example, in FIG. 8). The tubular member 301 comprises a second section 307 having a rear end carrying a coupling 304, said second section 307 being angled relative to the first section 306. As shown in Figures 4 and 8, the backflushing device 300 can be arranged so that the metal strip 102 is rolled around the straight first section 306 of the tubular member 301 and the backflow nozzle 302 is positioned in front of the welding coil in the direction of travel (T) of the tube 100.

[0036] Those skilled in the art will understand that the present disclosure is not limited to the preferred embodiments described above, and will further understand that modifications and variations are possible within the scope of the appended claims.

Claims

1. 1. A seam guide assembly (1) configured to maintain longitudinal edges (101) of a metal strip (102) being rolled into a tube (100) in position prior to welding the edges together in a welding section (201) of a welded tube roll forming apparatus (200), the seam guide assembly comprising: a front seam guide tip component (2) attached to a holder (3) such that an elongated tip (4) projects from a first side (5) of the holder (3), the tip (4) configured to be inserted between the tube edges (101) to be welded; A seam guide assembly (1), wherein the holder (3) is provided with a through channel (6), the channel having an inlet opening (7) located on the first side (5) of the holder and adjacent to the front seam guide tip component (2) in the longitudinal direction of the holder, and an outlet opening (8) located on the second side (9) of the holder, the outlet opening being configured to be connected to a vacuum source, A seam guide assembly (1) characterized in that the inlet opening (7) of the channel (6) has an elongated shape oriented in the longitudinal direction of the holder (3).

2. a rear seam guide tip component (10) attached to said holder (3) such that an elongated tip (11) protrudes from said first side (5) of said holder (3); 2. The seam guide assembly of claim 1, wherein the rear seam guide tip component (10) is positioned in the holder away from the front seam guide tip component (2) in the longitudinal direction of the holder, and the channel inlet opening (7) is located between the front tip component (2) and the rear tip component (10).

3. 3. The seam guide assembly according to claim 1 or 2, wherein the inlet opening (7) of the channel (6) has a width that does not exceed the outer diameter of the tube (100) and preferably corresponds approximately to the distance between the edges of the strip (102) that is formed into a substantially tubular shape.

4. The holder (3) is provided with a guide flange (12), The guide flanges (12) are located on each side of the channel inlet opening (7). The seam guide assembly according to any one of claims 1 to 3.

5. 1. A welded pipe roll forming apparatus (200) comprising a roll forming section (202) configured to form a metal strip (102) into a tube (100) followed by a welding section (201), the welding section (201) comprising a high frequency induction welding coil (203) and a pair of welding rollers (204) configured to weld together the longitudinal edges (101) of the metal strip (102) being rolled into the tube (100) while the tube is advanced through the apparatus in a direction of travel (T), a vacuum extraction section (205) configured to extract solid particles generated inside the tube (100) during high frequency induction welding of the tube edges; the vacuum extraction section (205) is located between the high frequency induction welding coil (203) and the roll forming section (202) where the edges (101) of the roll formed tube are not yet welded together; A welded pipe roll forming apparatus (200) characterized in that the vacuum extraction section (205) comprises a seam guide assembly according to any one of claims 1 to 4.

6. 6. The apparatus of claim 5, wherein the vacuum extraction section (205) is configured to be connected to a vacuum source and comprises a gap vacuum nozzle (206) arranged rearward of the seam guide assembly (208) in the direction of movement (T) of the pipe (100), the gap vacuum nozzle (206) being configured to extract solid particles through the opening between the edges of the pipe that are not yet welded.

7. the vacuum extraction section (205) comprises a tube vacuum nozzle (207) configured to be connected to a vacuum source and positioned rearward of the seam guide assembly (208) in the direction of movement (T) of the tube (100); 7. The apparatus of claim 5 or 6, wherein the tube vacuum nozzle (207) is configured to be positioned within the roll-formed, yet unwelded tube to extract solid particles present within the tube.

8. a backflushing device (300) comprising a tubular member (301) having a gas valve (302) attached to an outlet end (303) and a coupling (304) attached to an inlet end (305); the coupling is configured to be connected to a source of pressurized gas; The apparatus (200) according to any one of claims 5 to 7, wherein the backflushing device is configured to apply a gas flow in a direction opposite to the direction of movement (T) of the tube (100) at a position (P) in front of the welding coil (203) in the tube movement direction (T).

9. The apparatus (200) of claim 8, wherein the gas valve (302) is a reverse flow nozzle.

10. the tubular member (301) of the backflushing device (300) includes a straight first section (306) having a front end (303) to which the backflow nozzle (302) is attached; the straight section (306) has a length (L) that exceeds the distance from the rear end (13) of the seam guide assembly (1) to a position (P) in front of the welding coil (203) in the direction of movement (T) of the tube; 10. The apparatus of claim 8 or 9, wherein the first straight section (306) of the tubular member (301) has an outer diameter that is smaller than the inner diameter of the pipe (100) to be welded.

11. the tubular member (301) comprises a second section (307) having a rear end carrying the coupling (304); the second section (307) is angled relative to the first section (306); The backflushing device (300) preferably comprises a metal strip (102) rolled around the straight first section (306) of the tubular member (301); The device according to any one of claims 8 to 10, wherein the counterflow nozzle (302) is arranged in the device so as to be located in front of the welding coil in the direction of movement (T) of the tube (100).

12. A method for manufacturing a tube comprising aluminum or an alloy thereof, the method comprising the steps of: rolling a strip comprising aluminum or an alloy thereof into a tube (100) in a roll-forming section (202) of a welded tube roll-forming apparatus (200); and welding the tube edges (101) together in a high frequency induction welding section (201) of the apparatus, the high frequency induction welding section (201) comprising a welding coil (203) and a pair of welding rollers (204), 5. A method according to claim 1, wherein the welding step comprises extracting solid particles generated inside the tube (100) during the high frequency induction welding by application of a vacuum at a section (205) of the tube where the edges (101) of the roll-formed tube have not yet been welded together by the seam guide assembly according to any one of claims 1 to 4.

13. 13. The method of claim 12, further comprising backflushing the solid particles by applying pressurized gas in a direction opposite to the direction of movement (T) of the tube (100) at a position (P) in front of the welding coil (203) in the tube movement direction (T).

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