RU2847589C1 - Laser-arc module for orbital laser-arc welding of non-rotary circular pipe joints, a laser-arc welding device used in the laser-arc module, and a method for orbital laser-arc welding of non-rotary circular pipe joints using same - Google Patents

Abstract

FIELD: performing operations.

SUBSTANCE: invention relates to automatic welding of steel pipe joints by means of orbital welding using arc, laser or laser-arc welding technology and can be used for welding of fixed pipe circular joints, including with walls thickness of more than 15 mm. Laser-arc module comprises, at least, two laser-arc welding devices arranged on guide belt to displace clockwise and counter clockwise in one welding cycle. Proposed device comprises carriage arranged to be driven by bearing rollers and gear wheel. Carriage base accommodates laser welding head with optical system provided with focusing element, arc welding torch, sensors of angular position and pipe edge butt tracking sensors. Laser welding head is equipped with device for focusing element oscillatory movements. Laser-arc welding method is implemented by at least two devices, which are installed on the guide belt with possibility of moving clockwise and counter-clockwise in one welding cycle, wherein initial and final positions of devices are set so that weld seams overlap each other at the beginning and at the end of welding cycle. After welding cycle is completed, carriages are moved to initial position at maximum allowable speed. In welding, laser head focusing elements are oscillated in direction perpendicular to welding direction and device angular position is continuously controlled.

EFFECT: reduced time of welding, synchronous movement of devices during welding and reduced concentration of energy in welding bath.

8 cl, 3 dwg

Description

The invention relates to automatic welding of steel pipe joints by means of orbital welding using arc, laser or laser-arc welding technology and can be used for welding non-rotating circumferential pipe joints, including those with a wall thickness of more than 15 mm.

An orbital welding device for pipeline construction is known, which can be used in the construction of main pipelines (RU Patent No. 2355569, B23K 26/30, B23K 26/42, published on May 20, 2009). The device includes a guide hoop oriented relative to the first end of the pipe and the annular joint, and a trolley mounted so as to be moved by an electric motor along the guide hoop via a feed device. A laser welding head for laser welding is mounted on the trolley, which is configured to be oriented along the annular joint. The laser beam is generated by a high-power fiber laser located on a mobile vehicle, directed along a waveguide to the trolley and fed to the welding head. A welding head for MSG arc welding can be mounted on the trolley, with the possibility of combined action of the laser beam and the MSG arc in the laser welding zone or in separate process zones.

A laser-arc module for orbital welding of non-rotating circumferential pipe joints is known, selected as a prototype (RU Patent No. 2548842, B23K 26/02, published April 20, 2015). The module comprises a guide belt located on the pipe, a movable carriage mounted on the guide belt and capable of moving along the belt. The carriage contains a movement device mounted on the carriage base in the form of a system of supporting rollers and a gear wheel. Mounted on the carriage are a pipe joint tracking sensor and a manipulator consisting of two mutually perpendicular transverse and vertical linear guides that move relative to each other and are equipped with motors. A laser welding head and an arc welding torch are mounted on the transverse guide. During the welding process, a joint tracking sensor monitors the pipe joint; after processing, signals from this sensor are sent to a controller, which sends control signals to motors located on linear guides.

The disadvantage of known modules and devices for orbital welding of circumferential joints is the long time required for orbital welding and the occurrence of weld defects (burn-through, pores) due to the high specific energy density of the laser beam.

A device for the automatic welding of curved surfaces (USSR Author's Certificate No. 656776, B23K 31/08, published April 15, 1979) is known. It features a movement mechanism comprising a movement drive, a system of rollers, and gears. A welding head with a drive is mounted on the device in such a way that the welding head's coordinates are maintained during movement.

A laser-arc module is known, including a device for welding non-rotating circumferential pipe joints (RU Patent No. 2548842, B23K 26/02, published April 20, 2015), chosen as the prototype. The device comprises a carriage with a system of support rollers and a gear mounted on the carriage base. A laser welding head with an optical system featuring a focusing element and an arc welding torch are mounted on the device.

A disadvantage of the known device for orbital welding of circumferential joints is the inability to control its angular position and perform oscillatory movements of the laser welding head, which leads to defects in the weld (burn-through, pores) due to the high specific energy density of the laser beam.

A method for joining steel pipe ends using orbital welding using hybrid technology is known (EA Patent No. 017579, B23K 9/028, B23K 26/28, published January 30, 2013). The pipe ends, preferably with a wall thickness greater than 6 mm and a diameter greater than 150 mm, are joined with one or more weld layers. The laser welding head and the electric arc welding head are mounted on separate carriages on a ring rail, fixed in the welding zone around the pipe end, and during welding, they are independently moved and adjusted around the pipe circumference on the ring rail.

A known method for orbital laser-arc welding of non-rotating circumferential pipe joints (RU Patent No. 2548842, B23K 26/02, published April 20, 2015), adopted as a prototype, uses a movable carriage mounted on a guide belt located along the circumference of the pipe and moved by a movement device alternately in opposite directions, with the carriage moving in one direction per pass. The first welding pass is performed by moving the carriage clockwise from the 12 o'clock position to the 6 o'clock position. After completing the first pass, the carriage is repositioned. The second pass is performed by moving the carriage counterclockwise from the 12 o'clock position to the 6 o'clock position. During welding, the pipe joint is monitored using a sensor.

The disadvantages of known methods of orbital laser-arc welding include low productivity, especially when welding pipes with a wall thickness of more than 15 mm, due to the need to increase the number of welding cycles and, accordingly, carriage repositioning and the occurrence of weld defects (burn-through, pores) due to the high specific energy density of laser radiation.

The technical challenge is to develop a design for a laser-arc module for using at least two welding devices and the ability to move them clockwise and counterclockwise during one welding cycle and the ability to control the angular position of the welding devices.

The technical challenge is to develop a laser-arc welding device used in a laser-arc module, which consists of reducing the specific energy density of laser radiation in the weld zone and increasing the size of the weld pool.

The technical challenge is to develop a method for orbital welding of non-rotating circumferential pipe joints, including those with wall thicknesses greater than 15 mm, using a laser-arc module.

The technical result achieved by the laser-arc module for orbital welding of non-rotating circumferential joints of pipes consists in providing the possibility of moving each device clockwise and counterclockwise in one welding cycle, which reduces the welding time, and the focusing element of the optical system of the laser welding head to perform oscillatory movements, which makes it possible to reduce defects in welds (burn-throughs, pores) made by each device, due to a decrease in the specific energy density of laser radiation in the weld zone, an increase in the size of the weld pool and the elimination of non-fusion of the edges.

The technical result is achieved due to the fact that the laser-arc module for orbital welding of non-rotating circumferential pipe joints includes a guide belt, a laser-arc welding device placed thereon, comprising a carriage mounted so as to be able to move along the belt by means of a movement device implemented in the form of a system of supporting rollers and a gear mounted on the base of the carriage. A laser welding head with an optical system having a focusing element, an arc welding torch, and a sensor for tracking the joint of the pipe edges are also placed on the base of the carriage. According to the invention, the module comprises at least two devices, wherein each device is mounted so as to be able to move on the guide belt clockwise and counterclockwise during one welding cycle, and an angular position sensor, and the laser welding head is provided with a device for oscillating the focusing element of the optical system.

In a particular case, an optical system oscillation module is used as a device for performing oscillatory movements of the focusing element of the optical system of the laser welding head.

The technical result achieved by the device for laser-arc welding of non-rotating circumferential joints of pipes, used in the laser-arc module, consists in reducing defects in the weld seam (burn-throughs, pores) by reducing the specific energy density of laser radiation in the weld seam zone, increasing the size of the weld pool and eliminating lack of edge fusion.

A technical result achieved by a laser-arc welding device comprising a carriage movable by means of a movement device in the form of a system of supporting rollers and a gear mounted on the carriage base. A laser welding head with an optical system having a focusing element, an arc welding torch, and a pipe edge joint tracking sensor are also mounted on the carriage base. According to the invention, the device is equipped with an angular position sensor, and the laser welding head comprises a device for oscillating the focusing element of the optical system.

In a particular case, an optical system oscillation module is used as a device for oscillatory movements of the focusing element of the optical system of the laser welding head.

The technical result achieved by implementing the method for welding non-rotating circumferential joints, including those with wall thicknesses greater than 15 mm, using a laser-arc module and the device used in it, consists in reducing the welding time due to the formation of a weld seam during multidirectional movement of the carriages in one welding cycle and eliminating their reinstallation, as well as reducing weld defects (burn-through, pores) due to a decrease in the specific energy density of laser radiation in the weld zone and eliminating incomplete fusion of the edges.

The technical result is achieved due to the fact that the method of orbital laser-arc welding of non-rotating circumferential joints of pipes, including laser and arc welding, which are carried out using a laser-arc module with a device for laser-arc welding, containing a carriage mounted on a guide belt with the possibility of moving along it by means of a moving device made in the form of a system of bearing rollers and a gear wheel mounted on the base of the carriage, a laser welding head with an optical system having a focusing element and an arc welding torch are also placed on the base of the carriage, while during welding, monitoring of the pipe joint is carried out. According to the invention, welding is performed by at least two devices, each of which is mounted with the possibility of movement on a guide belt in opposite directions during one welding cycle, wherein the initial and final positions of the devices are set in such a way that at the beginning and at the end of the welding cycle the welds overlap each other, oscillations of the focusing elements of the optical systems of the laser welding heads are set in a direction perpendicular to the direction of welding, while the angular position of the devices is controlled.

In a particular case of performing the method, after welding, the carriages are moved to the initial position at the maximum permissible speed.

In a particular case of implementing the method, oscillatory movements of the focusing element of the optical system of the laser welding head are carried out with a frequency of at least 25 Hz.

In a particular case of the method implementation, during each subsequent welding cycle, the initial and final positions of the carriages are shifted in one direction along the weld seam to reduce its local thickenings in the places where the seams overlap.

Welding pipe joints using at least two devices in a laser-arc module, movable clockwise and counterclockwise during a single welding cycle without repositioning the devices. The initial and final positions of the devices are set so that the welds they produce overlap at the beginning and end of the welding cycle. This reduces welding time by more than half. By staggering the device start times in each welding cycle, the welds produced by each device overlap. Upon completion of the welding cycle, the devices are moved to their initial positions on the guide belt at the maximum permissible speed, allowing the second and subsequent welding cycles to begin earlier and reducing overall welding time. During each subsequent welding cycle, the initial and final positions of the devices are shifted in the same direction along the weld to reduce localized thickening at the points of weld overlap.

Control of the angular position of the laser-arc welding device using sensors installed on them is necessary for the coordinated and synchronized movement of the devices along the guide belt, preventing their collision.

A laser welding head with an optical system featuring a focusing element contains an electromechanical device, such as an oscillating module, that oscillates the focusing element. Oscillating movements of the laser welding head's focusing element, performed in a direction perpendicular to the welding direction, cause periodic displacement of the laser beam and increase the width of the weld pool, reducing the specific energy density of the laser radiation (the concentration of light energy). This reduces the likelihood of weld defects (burn-through, pores) and edge failure.

The focusing element's oscillation frequency must be at least 25 Hz. Increasing the oscillation frequency reduces the performance of the optical system's oscillation module, while decreasing it leads to instability of the weld pool's geometry.

The proposed invention is illustrated by drawings, where Fig. 1 schematically shows a laser-arc module with a device, Fig. 2 shows the initial position of the devices on the guide belt, and Fig. 3 shows the trajectories of movement of the devices during orbital welding.

In the figures shown, positions 1-13 show: 1 - pipe, 2 - guide belt, 3 and 4 - devices for laser-arc welding, 5 - carriage base, 6 - support rollers, 7 - gear wheel, 8 - arc welding torch, 9 - laser welding head with an optical system, 10 - focusing element of the laser head, 11 - swing module of the focusing element, 12 - edge joint tracking sensor, 13 - orbital carriage angular position sensor.

The laser-arc module contains a guide belt 2 located around the pipe 1 at a certain distance from the joint, and at least two devices 3 and 4 mounted on the guide belt with the ability to move along it in opposite directions - clockwise and counterclockwise in one welding cycle.

The device for laser-arc welding includes a carriage with a base 5, support rollers 6 and a toothed wheel 7. On the base of the carriage 5 there is an arc welding torch 8, installed in front of (along the welding direction) a laser welding head 9 with an optical system and a focusing element 10, provided with a device for swinging the focusing element 11 (for example, a swing module, an electromechanical device with an electronic control circuit) in a direction perpendicular to the welding direction, as well as a sensor for tracking the edge joint 12, providing guidance to the edge joint (welding seam) of the electrodes of the arc welding torch and the laser beam of the welding head, and an angular position sensor 13 for coordinated and synchronized movement of the device along the guide belt 2.

The movements of laser-arc welding devices 3 and 4 at the beginning and at the end of welding in the initial and next cycle are indicated by solid (A and B) and dashed (A' and B') lines, respectively, in Fig. 3.

The method of orbital laser-arc welding of non-rotating circular joints of pipes using a laser-arc module and a welding device is carried out as follows.

Before welding, laser-arc welding devices 3 and 4 with an arc welding torch 8, a laser welding head 9, a pipe joint tracking sensor 12 and a device angular position sensor 13 placed thereon are installed on a guide belt, with device 3 in the 12 o'clock position and device 4 in the 1 o'clock position. Welding is started by moving device 3 counterclockwise along trajectory A and, after it reaches the 10 o'clock position, device 4 is moved in idle mode to the 11 o'clock position and welding is started by moving clockwise along trajectory B.

When device 3 reaches the 5 o'clock position, welding is stopped and the device is moved at the maximum permissible speed to its starting position, the 12 o'clock position. Device 4 completes welding at the 6 o'clock position and is moved at the maximum permissible speed to its starting position, the 1 o'clock position. The welds produced by devices 3 and 4 overlap each other at the beginning and end of the welding cycle at the 11-12 o'clock and 5-6 o'clock positions. After welding, devices 3 and 4 are returned to their starting position at the maximum possible speed.

To perform the next welding cycle, the laser arc welding devices are placed in their initial positions and moved accordingly: device 3 to the 11 o'clock position and trajectory A', device 4 to the 12 o'clock position and trajectory B'. Welding begins with device 3 rotating clockwise, and after it reaches the 9 o'clock position, device 4 is moved in idle mode to the 10 o'clock position and begins counterclockwise welding. Welding ends with device 3 at the 4 o'clock position and device 4 at the 5 o'clock position. The welds overlap at the 10-11 o'clock and 4-5 o'clock positions.

Shifting the initial and final positions of laser arc welding devices prevents the formation of local thickenings of the seam during subsequent cycles.

During welding, the position of devices 3 and 4 is continuously monitored using an angular position sensor 13, for example, an inclinometer, to ensure coordinated and synchronized movement of the devices along the guide belt 2, preventing their collision, and continuous guidance of the laser head and arc torch to the welded joint is also carried out using a sensor 12 for tracking the joint of the pipe edges using, for example, a triangulation sensor.

During the welding process, both laser welding heads continuously oscillate the focusing element of the optical system at a frequency of at least 25 Hz in a direction perpendicular to the welding direction, causing periodic shifts of the laser beam across the weld joint. This increases the width and volume of the weld pool, preventing excessive energy concentration within the weld pool and reducing the likelihood of weld defects such as burn-through, pores, and edge incompleteness.

The proposed method of orbital welding of non-rotating circumferential pipe joints using a laser-arc module with a laser-arc welding device was tested by welding pipes with a diameter of 1420 mm and a wall thickness of 15.7 mm.

Before welding, the following parameters were set: laser power - 6 kW, arc power - 4 kW, welding speed - 0.6 m/min. Welding was performed in a shielding gas (80% argon, 20% carbon dioxide). The diameter of the Sv-08G2S welding wire was 1.2 mm. The oscillation frequency of the oscillation module was 25 Hz, the oscillation amplitude was 1.5 mm.

Before welding, two laser arc welding devices were placed on a guide rail mounted on the pipe. The devices were moved along the guide rail using a system of supporting rollers and a gear wheel mounted on the carriage base. The arc welding torch, mounted in front of (in the direction of welding) the laser welding head, was mounted on the carriage base. The torch had an optical system equipped with a focusing element and an oscillating module for oscillating movements perpendicular to the welding direction. A pipe joint tracking sensor and an angular position sensor for the device were mounted on the guide rail.

The devices were positioned at the 12 o'clock and 1 o'clock positions, respectively. Welding was initiated by moving the first device counterclockwise at the 12 o'clock position. Once it reached the 10 o'clock position, the second device was moved to the 11 o'clock position in an idle mode and began welding clockwise. When the first device reached the 5 o'clock position, welding was stopped and it was moved to its initial position, the 12 o'clock position, in an idle mode at a speed of 4 m/min, which was the maximum possible for the given pipe diameter and carriage design. Welding was completed by the second device at the 6 o'clock position and moved to its initial position, the 1 o'clock position, at the same speed. The weld pool length was 5 mm, and its width was 3 mm. The welds produced by the first and second devices at the beginning and end of the welding cycle overlapped each other at the 11-12 o'clock and 5-6 o'clock positions, respectively.

The position of the devices on the guide belt was controlled using an angular position sensor, which ensured coordinated and synchronized movement of the devices along the guide belt.

At each subsequent welding cycle, the initial and final positions of the devices were shifted in one direction along the weld seam relative to the previous welding cycle.

The welding time for one circumferential joint using two devices with eight welding cycles was 32 minutes. When welding using conventional methods that require reinstallation of the welding devices, the welding time under the same process parameters is at least 2.0 hours.

Ultrasonic testing of the welded seam did not reveal any defects in the form of burn-throughs, pores, or unmelted edges.

Thus, when implementing the proposed method of orbital welding of non-rotating circumferential pipe joints, including those with a wall thickness of more than 15 mm, using a laser-arc module with a laser-arc welding device, the welding time is reduced by more than half, stable and synchronous movement of the devices clockwise and counterclockwise during welding in one welding cycle is ensured, the specific energy density of laser radiation in the weld zone is reduced, the size of the weld pool is increased, defects in the weld and lack of edge fusion are reduced.

Claims (8)

1. A laser-arc module for orbital welding of non-rotating circumferential pipe joints, comprising a guide belt, a device for laser-arc welding of non-rotating circumferential pipe joints placed thereon, comprising a carriage mounted with the possibility of movement along the belt by means of a movement device made in the form of a system of supporting rollers and a gear wheel mounted on the base of the carriage, a laser welding head with an optical system having a focusing element, an arc welding torch and a sensor for tracking the joint of the edges of the pipes are also placed on the base of the carriage, characterized in that the module contains at least two devices, wherein each device is mounted with the possibility of movement on the guide belt clockwise and counterclockwise in one welding cycle, and an angular position sensor, and the laser welding head is provided with a device for oscillatory movements of the focusing element of the optical system. 2. A laser-arc module according to paragraph 1, characterized in that a swing module of the optical system is used as a device for performing oscillatory movements of the focusing element of the optical system of the laser welding head. 3. A device for laser-arc welding of non-rotating circumferential joints of pipes, used in the module according to paragraph 1, containing a carriage, configured to move by means of a system of supporting rollers and a gear wheel mounted on the base of the carriage, a laser welding head with an optical system having a focusing element, an arc welding torch and a sensor for tracking the joint of the edges of the pipes are also placed on the base of the carriage, characterized in that the device is equipped with an angular position sensor, and the laser welding head contains a device for oscillatory movements of the focusing element of the optical system. 4. The device according to paragraph 3, characterized in that the device for performing oscillatory movements of the focusing element of the optical system of the laser welding head is an oscillating module of the optical system. 5. A method for orbital laser-arc welding of non-rotating circumferential pipe joints using a laser-arc module according to claim 1, comprising laser and arc welding, which are carried out using a laser-arc module with a device for laser-arc welding containing a carriage mounted on a guide belt with the ability to move along it by means of a moving device made in the form of a system of supporting rollers and a gear wheel mounted on the base of the carriage, a laser welding head with an optical system having a focusing element and an arc welding torch are also placed on the base of the carriage, wherein during welding, tracking of the pipe joint is carried out, characterized in that welding is performed by at least two devices, each of which is mounted with the ability to move on the guide belt in opposite directions in one welding cycle, wherein the initial and final positions of the devices are set in such a way that at the beginning and at the end of the welding cycle, the welds overlap each other, oscillations of the focusing elements are set optical systems of laser welding heads in a direction perpendicular to the welding direction, while controlling the angular position of the devices. 6. The method according to paragraph 5, characterized in that after welding the devices are moved to their original position at the maximum possible speed. 7. The method according to paragraph 5, characterized in that the oscillatory movements of the focusing element of the optical system of the laser welding head are carried out at a frequency of at least 25 Hz. 8. The method according to paragraph 5 or 6, characterized in that with each subsequent welding cycle, the initial and final positions of the devices are shifted in one direction to reduce local thickenings of the weld seam at the overlap points.