Automatic welding machine for processing vertical fins on pipes

Abstract

The automatic welding machine can be used for longitudinal finning of pipes, including small diameters with closely spaced "narrow" trough-like ribs. The automatic welding machine includes a number of clamping units arranged symmetrically around the circumference, each of which includes a pressurized pneumatic cylinder, a compression driver, and a resistance welding roller for applying pressure and supplying the welding current, and a die for positioning the ribs relative to the pipe and the clamping units, and for passing the rollers. Each clamping unit includes a mechanism for adjusting the position of the longitudinal axis of the compression driver of the resistance welding roller, which includes a compression driver guide, two eccentric adjusters, a compression driver housing, a ball joint, an adjustment lock nut, a mounting screw, and two bronze nuts, and a mechanism for adjusting the resistance welding roller, which includes left and right bushings, left and right nuts, left and right cheeks, a mounting screw, and a mounting bolt. The die includes a mechanism for positioning the rear of the die relative to the axis of the resistance welding roller, which includes a die body, a die body centralizer, a radial rack, an axial rack, a turnbuckle, a turnbuckle centralizer, a resistance welding roller, and a plate. The number of clamping units corresponds to the number of 8 ribs to be welded simultaneously.

Description

[Technical field]

[0001] The present invention relates to an automatic welding machine for manufacturing heat exchangers, which can be applied in various fields of power engineering where longitudinally finned pipes are used.

[0002] Automatic welding machines can be used for longitudinal finning of pipes, including small diameters with closely spaced "narrow" trough-like ribs (Figure 1).

[0003] To increase the thermal efficiency of a vertically finned pipe, it is necessary to weld as many trough-shaped ribs as possible to the pipe surface, the number of ribs depending on the width of the rib and the feasibility of making a quality weld by resistance seam spot welding. [Background technology]

[0004] Highly efficient longitudinally finned pipes are currently designed with "narrow" trough-like ribs, where the width of the fin flange (Fig. 2, width "a") where the rib is welded must not exceed 10% of the minimum width of the welding roller. For high-quality welding of such ribs to the pipe, the axes of symmetry of the welding rollers must be precisely aligned.

[0005] An automatic welding machine is known, in which six welding rollers are arranged circumferentially, and a rib with a trough-like profile is pressed out by the action of a pneumatic cylinder (USSR Authorship Certificate No. 454617, V23K 31 / 08, issued on January 30, 1989).

[0006] The closest in technical essence and achieved results is the technical solution implemented in the design of the vertical fin processing machine (OC-1414, Technical Specification TU10-13-102-83, 1983). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] USSR Patent Invention No. 1454617 Summary of the Invention [Problem to be solved by the invention]

[0008] The technical problem of the proposed solution is to improve the quality of the resulting longitudinally finned pipe by increasing the joining accuracy of the welded parts.

[0009] The technical result is to improve the quality of the finned pipe and improve the heat transfer performance. [Means for solving the problem]

[0010] The object is achieved by an automatic welding machine for processing vertical fins on pipes, comprising: a plurality of clamping units arranged symmetrically along a circumference, each of which includes a pressurized pneumatic cylinder, a compression driver, and a resistance welding roller for pressurizing and supplying a welding current; and a die for positioning a rib relative to the pipe and the clamping units, the die having a window for the passage of the rollers, each clamping unit having a mechanism for adjusting the position of the longitudinal axis of the compression driver of the resistance welding roller, the mechanism including a compression driver guide, two eccentric adjusters, a compression driver housing, a ball joint, an adjusting lock nut, a mounting screw, and two bronze nuts; and a mechanism for adjusting the resistance welding roller, the mechanism including left and right bushings, left and right nuts, left and right cheeks, a mounting screw, and a mounting bolt; the die including a mechanism for positioning the rear of the die relative to the axis of the resistance welding roller, the mechanism including a die body, a die body centralizer, a radial rack, an axial rack, a turnbuckle, a turnbuckle centralizer, a resistance welding roller, and a plate; and the number of clamping units corresponds to the number of 8 ribs to be welded simultaneously.

[0011] This allows the position of the longitudinal axis of the compression driver of the resistance welding roller to be adjusted, for example during initial start-up of the machine or when servicing the compression driver, and also allows adjustment of the position of the compression driver guide relative to the compression driver as necessary to compensate for uneven wear of the bronze nut.

[0012] The invention is illustrated by the drawings. [Brief description of the drawings]

[0013] [Figure 1] Figure 1 shows a 16 mm diameter finned pipe with eight closely spaced "narrow" trough-like ribs. [Diagram 2] FIG. 1 shows a "narrow" rib for vertical finning of a pipe. [Diagram 3] FIG. 1 shows a resistance welding roller for welding eight trough-shaped ribs to a pipe. [Figure 4] FIG. 13 illustrates a mechanism for adjusting the position of the longitudinal axis of the compression driver of the resistance welding roller. [Diagram 5] FIG. 13 illustrates a mechanism for fine-tuning the position of the compression driver guide of the resistance welding roller. [Figure 6] FIG. 13 is a diagram showing a mechanism for adjusting the position of the resistance welding roller. [Figure 7] FIG. 13 shows the mechanism for positioning the rear of the die relative to the axis of the resistance welding roller. [Figure 8] FIG. [Figure 9] FIG. 13 shows the position of the resistance welding rollers and liners in the die. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The mechanism for adjusting the position of the longitudinal axis of the compression driver of the resistance welding roller (FIG. 4) comprises a compression driver 19, a compression driver guide 1, an eccentric adjuster 2, a compression driver housing 3, a ball joint 4, a pneumatic cylinder 5, and a mounting screw 6.

[0015] The alignment of the longitudinal axis 43 (FIGS. 4, 6) of the compression driver of the resistance welding roller with the corresponding machine axis 44 (FIG. 3) is carried out by rotating the eccentric adjuster 2 (FIG. 4) within an angle of ±90°.

[0016] To adjust the compression driver, the four mounting screws 6 are loosened and the rotation of the eccentric adjusters 2 is adjusted to rotate or move the compression driver the required amount. The angle of rotation or amount of movement is controlled by a suitable measuring device. The hole where the driver is mounted to the housing 3 is larger in diameter than the mounting screws 6 by the amount of eccentricity of the eccentric adjusters 2.

[0017] The mechanism for fine-tuning the position of the compression driver guide of the resistance welding roller (FIG. 5) comprises an adjustment screw 7, a mounting bolt 8, a lock nut 9, a left bronze nut 10, a right bronze nut 11, the compression driver guide 1, and the compression driver housing 3.

[0018] When fine adjustment of the position of the resistance welding roller compression driver guide 1 (FIG. 5) relative to the compression driver housing 3 is performed to compensate for uneven wear of the bronze nuts 10, 11, first loosen the lock nuts 9 on each mounting bolt 8 and each adjustment screw 7.

[0019] The holes for the mounting bolts 8 are oval to allow for positional displacement of the nuts 10, 11 by each adjustment screw 7. Each adjustment screw 7 tightens the bronze nuts 10, 11 evenly onto the compression driver guide 1. The evenness is assessed by the rotation angle of the adjustment screw 7.

[0020] Afterwards, the contact accuracy of the resistance welding roller with the control die and the smoothness of the operation of the compression driver at a pressure of 0.5 atm are checked. To reduce the adverse effects on the operation of the compression driver due to possible misalignment of the axis, a ball joint 4 is installed between the pneumatic cylinder 5 (Fig. 4) and the compression driver guide 1. After adjustment and checking, the lock nuts 9 (Fig. 5) are tightened on each adjustment screw 7 and each mounting bolt 8 is fixed.

[0021] The mechanism for adjusting the position of the resistance welding roller (FIG. 6) includes a resistance welding roller 12, a right bushing 13, a right nut 14, a right cheek 15, a left cheek 16, a left nut 17, a left bushing 18, a compression driver element 19, a mounting screw 6, and a central bolt 20.

[0022] The mechanism for adjusting the position of the resistance welding rollers works as follows.

[0023] By loosening the central bolt 20 and the screws 6 of the right cheek 15 and the left cheek 16, the right nut 14 and the left nut 17 can be freely adjusted. To move the resistance welding roller 12 to the right, the right nut 14 must be loosened as much as necessary and the left nut 17 must be tightened until it stops. The threaded connections of the nuts 14, 17 with the parts of the compression driver element 19 allow the resistance welding roller 12 to move the required amount together with the bushings 13, 18.

[0024] The correct position of the resistance welding roller is controlled by equalizing the distance between the resistance welding roller 12 and the left and right ribs. A template, dipstick or other measuring device can be used to measure the distance.

[0025] After the resistance welding roller 12 is mounted in the required position, the bolt 20 must be tightened to fix the relative position of the nuts 14 and 17, and then the cheek tightening screw must be tightened for good current supply to the nuts. The nut-bushing system constitutes a plain bearing that transmits the current.

[0026] The mechanism for positioning the rear of the die 42 (FIG. 7) relative to the axis of the resistance welding roller includes the die body centralizer 21, die 22, die body 23, radial rack 24, axial rack 25, turnbuckle centralizer 26, turnbuckle 27, resistance welding roller 12, and plate 29. Because each compression driver 19 (FIG. 3) is located close to each other, the radial fixed rack 24 of the die extends well beyond the dimensions of the compression drivers. This is to allow for proper maintenance of the compression drivers.

[0027] Due to the large dimensions of the structure consisting of radial racks 24 and axial racks 25 (Fig. 7) designed to hold and position the mold body 23 relative to the longitudinal axis of the welded pipe 44, the fixing of the rear part 42 of the mold is insufficiently rigid. Therefore, the rear part 42 of the mold can deviate up to 2 mm from the axis of the welding roller due to misalignment of the compression driver forces, leading to bending of the pipe with longitudinal fins, including unacceptable bending. Therefore, it is proposed to use a mechanism for positioning the rear part of the mold by providing the body with a second support with high rigidity at the point of maximum displacement of the mold body.

[0028] The mechanism works as follows.

[0029] The rear 42 of the mold body 23 fits tightly within the mold body centralizer 21, which is connected to the plate 29 by axial racks 25 at the attachment points to the body using turnbuckles 27 and turnbuckle centralizers 26, and further connected to the plate 29 and the front 41 of the mold body 23 by radial racks 24 at the attachment points to the body.

[0030] During the test run, the position of the rear part 42 of the mold body is adjusted by tensioning (twisting) the turnbuckles 27. The permissible displacement between the longitudinal axis of the rear part 42 of the mold body and the front part 41 of the mold body must not exceed 0.5 mm. All four turnbuckles 27 must be tightened.

[0031] The mold 22 (FIG. 8) comprises a mold base 32, an exchangeable module 23, liners 38, 39, a key 33, a screw 34 for fixing the key, a screw 35 for fixing the exchangeable mold module, a pin 36, and a screw or screw 37 for fixing the liner. The base of the mold body is reusable and made of austenitic steel. The exchangeable module is made of wear resistant steel type 40X hardened to 38-42 HRC.

[0032] Four liners 38 (FIG. 9) are made of insulating material and the other four liners 39 are made of metal having anti-friction properties.

[0033] An insulating liner 38 is placed between the ribs that are included in one welding circuit (the ribs being welded by the resistance welding rollers 12 from one welding transformer 40).

[0034] The insulating liner 38, due to its short service life, positions the ribs less properly on the pipe, but it eliminates shunts in the circuit along the "welding roller-rib-liner-rib-welding roller" chain and prevents defects such as "seizure" from appearing on the walls of the ribs.

[0035] The metal liner 39 has a long service life so that the ribs are properly positioned on the pipe.

[0036] By combining a metal liner 39 with an insulating liner 38 in the proposed sequence, the service life of the latter is increased by up to five times, reducing the line maintenance effort and improving the quality of the finned pipe.

[0037] Once the automatic welder is armed, it operates as follows.

[0038] Before the machine start-up and once a month, the alignment of the compression driver of the resistance welding roller is adjusted by adjusting its position using a mechanism that adjusts the position of the longitudinal axis of the compression driver of the resistance welding roller. Similarly, at the start of the machine and during open periods, for example once or twice a year, a positioning mechanism adjusts the alignment of the rear of the die with respect to the axis of the resistance welding roller. Before the start of welding, the position of the resistance welding roller with respect to the rib must be adjusted so that the deviation of the symmetrical axis does not exceed 0.2 mm for each shift.

[0039] The pipe and the eight trough-shaped ribs are simultaneously transported by a towing trolley to the welding zone under each resistance welding roller, where each trough-shaped rib is pressed against the pipe with a controlled force by a corresponding resistance welding roller, and a welding current is supplied to the rib through the rollers according to a set cyclogram.

[0040] The trolley included in the automatic welding machine allows uniform movement of the pipe and the weld rib with adjustable welding speed.

[0041] By using an automatic welding machine for processing longitudinal fins on pipes, it is possible to produce high-quality longitudinal finned pipes, and the design with eight ribs allows to increase the heat transfer characteristics of heat exchange equipment.

Claims

1. An automatic welding machine for processing vertical fins on pipes, a plurality of clamping units arranged symmetrically around a circumference, each of which includes a pressurized pneumatic cylinder, a compression driver, and a resistance welding roller for applying pressure to the welding current; a die for positioning the rib relative to the pipe and the clamp unit and for providing a window for the roller to pass through; Each clamp unit has a mechanism for adjusting the position of the longitudinal axis of the compression driver of the resistance welding roller, the mechanism including a compression driver guide, two eccentric adjusters, a compression driver housing, a ball joint, an adjustment lock nut, a mounting screw, and two bronze nuts, and a mechanism for adjusting the resistance welding roller, the mechanism including left and right bushings, left and right nuts, left and right cheeks, a mounting screw, and a mounting bolt; The automatic welding machine is characterized in that the die includes a mechanism for positioning the rear of the die relative to the axis of the resistance welding roller, the mechanism including a die body, a die body centralizer, a radial rack, an axial rack, a turnbuckle, a turnbuckle centralizer, a resistance welding roller, and a plate.

2. 2. The automatic welding machine according to claim 1, wherein the number of clamping units corresponds to eight ribs to be welded simultaneously.

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