Intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh

Abstract

The present invention relates to the field of welding process equipment, and discloses an intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh, which includes a container body, a welding equipment system, a welding fixture system, a data acquisition and display system, a track inside the box, an electrical control box, an environmental protection facility system, and a track outside the box. The workstation uses two welding robots to weld simultaneously, and is provided with two flexible workbenches, so that the workpiece welding and the positioning and assembly processes of the welded parts are cycled and alternated, thereby improving production efficiency. Through the two welding robots and the data acquisition and display system, the automation and intelligent management of the welding operation are realized, the conformity and consistency of the product welding quality are ensured, and the environmental impact and occupational hazards to the operators are eliminated. Moreover, the workstation has the characteristics of strong versatility and can be applied to the production of nearly 100 kinds of products. The workstation uses a load-carrying vehicle to transfer with the high-speed railway box girder construction site, and can be operated without reinstallation and debugging.

Description

Technical Field

[0001] The invention relates to the field of welding process equipment, and in particular to an intelligent integrated welding workstation for high-speed railway box girder pipeline positioning meshes. Background Art

[0002] The roadbed of high-speed railway is a reinforced concrete structure with a box-like appearance and a hollow interior, so it is called a box girder. The length of the high-speed railway box girder is divided into two types: 24m and 32m. A box girder pipeline positioning mesh is set every 0.5m section in the length direction. The positioning mesh is a flat grid-type welded assembly made of Φ12mm steel bars after cutting, bending and spot welding. At present, the positioning mesh is made by manual welding in an open operation room built on site. This working method is inefficient and often becomes a bottleneck process in the construction progress of the box girder. In addition, manual welding is difficult to ensure the quality and consistency requirements of the product welding size and appearance. In addition, the smoke generated by on-site arc welding will affect the surrounding environment, cause environmental pollution, and endanger the health of the operator. Summary of the invention

[0003] The purpose of the present invention is to provide an intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh. By adopting two welding robots to weld at the same time and setting two flexible workbenches, workpiece welding and workpiece positioning and assembly can be carried out simultaneously, while improving production efficiency, ensuring product welding quality, and reducing the impact on the environment and occupational hazards of operators.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: an intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh, including a container body 9, wherein the container body 9 is provided with a welding equipment system, a welding fixture system, a data acquisition and display system 10, an inner box track 11, an electrical control box 12, and an environmental protection facility system, and a detachable outer box track 15 is provided outside the container body 9; the welding fixture system includes: a flexible workbench A5, a flexible workbench B6, a workbench driving device 7, and a workbench positioning device 8, wherein the flexible workbench A5 and the flexible workbench B6 are frame structures composed of a workbench skeleton 18, which are respectively in a concave shape, and the workbench skeleton 18 is composed of multiple The flexible workbench B6 is composed of a lower cross bar 22, an upper cross bar 26 and a straight bar 27; the workbench driving device 7 can move along the lateral direction of the container body 9; the welding equipment system includes: a welding robot A1, a welding robot B2, a robot control box A3, and a robot control box B4. The welding robot A1 and the welding robot B2 are installed and fixed in the middle position of the container body floor 17, and the distance between the two should match the welding range of the workpiece. The robot control box A3 and the robot control box B4 are installed and fixed side by side on the container body floor 17 on the right side of the flexible workbench B6; the environmental protection facility system includes: a welding fume purifier 13 and a welding fume and arc isolation cover 14.

[0005] Furthermore, an electrical control box 12 is fixedly installed above the robot control box A3 and the robot control box B4, and a plurality of touch switches 16 for controlling related motors or electrical appliances are arranged on the surface of the electrical control box 12.

[0006] Furthermore, the flexible workbench B6 is a workbench frame 18 frame structure formed by welding and assembling square steel pipes, presenting a "concave" shape, and a plurality of middle welding fixtures 19, a left welding fixture 20, and a right welding fixture 21 are arranged on the workbench frame 18; the lower cross bars 22 at the two outer ends of the workbench frame 18 are respectively installed with two mutually symmetrical inverted V-shaped rollers 23, and an inverted V-shaped roller 23 is installed on the inner side of the lower cross bar 22 in the middle of the workbench frame 18, and the installation position of the inverted V-shaped roller 23 matches the track 11 in the box, so The inner rail 11 has three parallel rails and are fixed to the container body floor 17 with multiple bolts. The inner rail 11 and the outer rail 15 are X-shaped steel with a V-shaped top. The bottom surface of the inner rail 11 and the bottom surface of the outer rail 15 are connected at the edge of the container body floor 17 by a dovetail groove. An adjustment seat 24 is provided at the lower part of the outer end of the outer rail 15, and a baffle 25 is welded on the upper surface; the left welding fixture 20 and the right welding fixture 21 have the same structure and are symmetrically arranged at both ends of the workbench frame 18 of the flexible workbench B6.

[0007] Furthermore, the flexible workbench A5 and the flexible workbench B6 have the same structural form and are arranged relative to each other, but the length, width and height of the flexible workbench A5 are larger than those of the flexible workbench B6. Therefore, when there is no welding operation, most of the flexible workbench B6 can be stored inside the flexible workbench A5 to achieve overlapping placement.

[0008] Furthermore, the intermediate welding fixture 19 includes an intermediate plate 191, a large bolt 192, an intermediate longitudinal positioning block 193, an intermediate transverse positioning block 194, a small bolt A195, and a workpiece clamp A196; the intermediate plate 191 is fixed to the workbench frame 18 by large bolts 192 at four corners, and a plurality of intermediate longitudinal positioning blocks 193 and intermediate transverse positioning blocks 194 are installed and welded on the upper surface of the intermediate plate 191 according to the specifications of the workpiece, and a plurality of grooves for movable cooperation with the workpiece are arranged on the intermediate longitudinal positioning blocks 193 and the intermediate transverse positioning blocks 194, and one or more workpiece clamps A196 are fixedly installed on the intermediate plate 191 by small bolts A195 next to the intermediate longitudinal positioning blocks 193 and the intermediate transverse positioning blocks 194.

[0009] Furthermore, the left welding fixture 20 includes an end plate 201, a positioning protrusion 202, a manual fastener 203, a buckle 204, an end longitudinal positioning block 205, an end transverse positioning block 206, a small bolt B, and a workpiece clamp B208; the end plate 201 is provided with four notches for active cooperation with four positioning protrusions 202 welded and fixed on the workbench frame 18, and is connected with the buckle 204 installed on the side of the end plate 201 through multiple manual fasteners 203 fixedly installed on the side of the upper cross bar 26; multiple end longitudinal positioning blocks 205 and end transverse positioning blocks 206 are installed and welded on the upper surface of the end plate 201 according to the specifications of the workpiece, and multiple grooves for active cooperation with the workpiece are provided on the end longitudinal positioning blocks 205 and the end transverse positioning blocks 206, and multiple workpiece clamps B208 are fixedly installed on the end plate 201 by small bolts B next to the end longitudinal positioning blocks 205 and the end transverse positioning blocks 206.

[0010] Furthermore, the workbench driving device 7 includes: a rack 701, a reduction motor 702, and a gear 703; the rack 701 is fixedly mounted on the lower surfaces of the auxiliary lower crosspiece 22 on both sides of the workbench frame 18, and the gear 703 is fixedly mounted on the protruding end of the rotating shaft of the reduction motor 702, and should be able to maintain good meshing with the rack 701 throughout the entire length, and the reduction motor 702 is fixedly mounted on the container body floor 17.

[0011] Furthermore, the flexible workbench A5 and the flexible workbench B6 are respectively provided with two sets of workbench driving devices 7 .

[0012] Furthermore, the workbench positioning device 8 comprises: a positioning plate 801, a cylinder 802, a cylinder bracket 803, a positioning pin 804, a sensor bracket 805, and a limit sensor 806; the positioning plate 801 is welded and fixed on the upper surface of the straight gear 27, the protruding end of the cylinder 802 serves as a positioning pin 804 and is movably matched with the positioning hole on the positioning plate 801, the cylinder 802 is fixed on the cylinder bracket 803, and a sensor bracket 805 and a limit sensor 806 installed on its upper surface are also arranged next to the cylinder bracket 803, and the bottom ends of the cylinder bracket 803 and the sensor bracket 805 are fixed to the container body floor (17).

[0013] Furthermore, the flexible workbench A5 and the flexible workbench B6 are respectively provided with two sets of workbench positioning devices 8 , and the two sets of workbench positioning devices 8 are symmetrically installed on the inner side of the straight block 27 of the workbench frame 18 .

[0014] Furthermore, the welding fume purifier 13 is bolted to the top of one end of the container body 9, and the welding fume and arc isolation cover 14 is installed on the top of the two inner side walls of the container body 9, and the retraction and extension are controlled by the corresponding touch switch 16 on the electrical control box 12. Further, the data acquisition and display system 10 includes a robot control box A3, a robot control box B4, a programmable controller, an intelligent electronic signboard and a server (not shown in the figure outside the container body 9), the programmable controller and the intelligent electronic signboard are fixedly installed in the middle position of the top of the container body 9, the output end of the programmable controller is connected to the input end of the intelligent electronic signboard, the output end of the intelligent electronic signboard is connected to the server, and the input end of the programmable controller is connected in parallel with the robot control box A3 and the robot control box B4, and the electrical control box 12.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. By using two welding robots to perform welding operations at the same time and setting up two flexible workbenches, the welding, positioning and assembly processes of the workpiece to be processed can be carried out alternately and cyclically at the same time, greatly improving the utilization efficiency of the workstation and achieving a production efficiency that is about ten times higher than that of the existing technology.

[0017] 2. Through the welding equipment system and data acquisition and display system, the welding operation is automated and intelligently managed. Through the control of pre-input welding operation data, the welding quality is greatly improved, ensuring product compliance and consistency.

[0018] 3. Since the entire welding work is automated and an environmental protection facility system is installed in the welding workstation, the impact of welding smoke on the surrounding environment is reduced, and the occupational hazards caused by operators inhaling welding smoke during on-site processing operations are avoided.

[0019] 4. The welding workstation of the present invention has strong versatility. By quickly exchanging the left welding fixture and the right welding fixture on the flexible workbench, the workstation can be applied to the production of nearly 100 kinds of specifications of products, thus achieving the purpose of universal production.

[0020] 5. The workstation is based on a container and is moved to the construction site of the high-speed railway box girder using a load-carrying truck. The workstation can be conveniently and quickly transferred to the new site, and there is no need to reinstall or debug at the new site, and operations can be carried out directly. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 : Schematic diagram of the structure of the intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh;

[0022] Figure 2 : Schematic diagram of the structure of flexible workbench B;

[0023] Figure 3 : Schematic diagram of the structure of the intermediate welding fixture;

[0024] Figure 4 : Schematic diagram of the structure of the left welding fixture or the right welding fixture;

[0025] Figure 5 : Schematic diagram of the workbench driving device structure;

[0026] Figure 6 : Schematic diagram of the workbench positioning device structure;

[0027] Figure 7 : Block diagram of the working unit of the data acquisition and display system;

[0028] Figure numerals: welding robot A1, welding robot B2, robot control box A3, robot control box B4, flexible workbench A5, flexible workbench B6, workbench driving device 7, workbench positioning device 8, container body 9, data acquisition and display system 10, track inside the box 11, electrical control box 12, welding fume purifier 13, welding fume and arc isolation cover 14, track outside the box 15, touch switch 16, container body floor 17, workbench frame 18, middle welding fixture 19, left welding fixture 20, right welding fixture 21, lower cross bar 22, inverted V-shaped roller 23, adjustment Seat 24, baffle 25, upper cross bar 26, straight bar 27; middle plate 191, large bolt 192, middle longitudinal positioning block 193, middle transverse positioning block 194, small bolt A195, workpiece clamp A196; end plate 201, positioning protrusion 202, manual fastener 203, buckle 204, end longitudinal positioning block 205, end transverse positioning block 206, workpiece clamp B208; rack 701, reduction motor 702, gear 703; positioning plate 801, cylinder 802, cylinder bracket 803, positioning pin 804, sensor bracket 805, limit sensor 806. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] See also Figure 1-7In the embodiment of the present invention, firstly, the six outer rails 15 respectively arranged on both sides of the container body 9 are installed and adjusted, the power is turned on for the entire welding workstation, and the touch switches 16 on the surface of the electrical control box 12 are turned on in sequence. The workbench driving device 7 starts the flexible workbench B6 to move along the inner rail 11 and the outer rail 15 to the outside of the container body 9. At this time, the operator positions and clamps the steel bars of various specifications of the positioning mesh on the middle welding fixture 19, the left welding fixture 20, and the right welding fixture 21 of the flexible workbench A5. When the positioning and clamping work of the steel bars is completed, the welding robot A1 and the welding robot B2 perform welding construction operations on the workpiece according to the pre-set process parameters. At the same time, the welding fume purifier 13 and the welding fume and arc isolation cover 14 are started to control the fume generated during the welding operation and reduce the pollution of the fume to the surrounding environment. When the flexible workbench A5 is welding the positioning mesh inside the container body 9, the operator will position and clamp the steel bars of various specifications of the positioning mesh on the middle welding fixture 19, the left welding fixture 20, and the right welding fixture 21 of the flexible workbench B6 outside the container body 9. When the welding of the workpiece on the flexible workbench A5 is completed, the workbench driving device 7 is started to move the flexible workbench A5 along the inner track 11 and the outer track 15 to the outside of the container body 9 until it stops at the baffle of the outer track 15, and then the operator will remove the processed workpiece from the middle welding fixture 19, the left welding fixture 20, and the right welding fixture 21. At the same time, the workbench driving device 7 moves the flexible workbench B6 and the steel bars to be processed clamped on the flexible workbench B6 into the interior of the container body 9 until the positioning pin 804 at the protruding end of the cylinder 802 is inserted into the positioning hole on the positioning plate 801 under the action of the limit sensor 806. After ensuring the precise positioning of the flexible workbench B6, the welding robot A1 and the welding robot B2 start welding the workpiece on the flexible workbench B6 according to the pre-set process parameters. At the same time, the welding fume purifier 13 and the welding fume and arc isolation cover 14 are started.

[0031] While the flexible workbench B6 is welding steel bars inside the container body 9, the operator can position and clamp the steel bars of various specifications of the positioning mesh on the middle welding fixture 19, the left welding fixture 20, and the right welding fixture 21 of the flexible workbench A5, respectively, to prepare for the next round of welding machine processing. The above operations are repeated in a cycle, so that two welding robots can work at the same time. With the two flexible workbenches, the welding, positioning, and assembly of the workpieces to be processed can be carried out simultaneously, and the utilization rate of the welding robot equipment is increased to more than 80%. The process parameters and production information of the welding process are controlled by the data acquisition and display system 10. The process and environmental parameters pre-input by the robot control box A3 and the robot control box B4, as well as the product code and quantity controlled by the electrical control box, the equipment operation status and other information are displayed on the intelligent electronic signboard through the programmable controller, which is convenient for the operator to timely understand the implementation of the welding operation, and transmit all relevant product production, equipment operation and other information of the welding operation to the server for storage and ordering.

[0032] By matching the manual fastener 203 with the buckle 204 on the left welding fixture 20 and the right welding fixture 21, the left welding fixture 20 and the right welding fixture 21 on the flexible workbench can be quickly switched, so that one workstation can be suitable for producing nearly 100 kinds of straight and curved positioning meshes of two types of high-speed railway box girders with lengths of 24m and 32m. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

Claims

1. An intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh, comprising a container body (9), characterized in that: The container body (9) is provided with a welding equipment system, a welding fixture system, a data acquisition and display system (10), an inner track (11), an electrical control box (12), and an environmental protection facility system, and a detachable outer track (15) is provided outside the container body (9); The welding fixture system comprises: a flexible workbench A (5), a flexible workbench B (6), a workbench driving device (7), and a workbench positioning device (8); the flexible workbench A (5) and the flexible workbench B (6) are frame structures formed by a workbench frame (18), each of which is in a concave shape; the workbench frame (18) is composed of a plurality of lower cross bars (22), an upper cross bar (26), and a straight bar (27); the workbench driving device (7) can move in the lateral direction of the container body (9); The welding equipment system comprises: a welding robot A (1), a welding robot B (2), a robot control box A (3), and a robot control box B (4); the welding robot A (1) and the welding robot B (2) are installed and fixed in the middle position of the container body floor (17); the distance between the two should match the welding range of the workpiece; the robot control box A (3) and the robot control box B (4) are installed and fixed side by side on the container body floor (17) on the right side of the flexible workbench B (6); A left welding fixture (20) and a right welding fixture (21) are respectively arranged at the two ends of the workbench frame (18), and a plurality of middle welding fixtures (19) are arranged in the middle of the workbench frame (18); the left welding fixture (20) and the right welding fixture (21) have the same structure and are symmetrically arranged at the two ends of the workbench frame (18) of the flexible workbench B (6); two mutually symmetrical inverted V-shaped rollers (23) are respectively installed on the lower crosspieces (22) at the two outer ends of the workbench frame (18), and an inverted V-shaped roller (23) is installed on the inner side of the lower crosspiece (22) in the middle of the workbench frame (18). shaped roller (23), the installation position of the inverted V-shaped roller (23) matches the inner rail (11), the inner rail (11) has three parallel rails and is fixed to the container body floor (17) with a plurality of bolts, the inner rail (11) and the outer rail (15) are V-shaped steel with a top, the bottom surface of the inner rail (11) and the bottom surface of the outer rail (15) are connected at the edge of the container body floor (17) by a dovetail groove, the lower part of the outer end of the outer rail (15) is provided with an adjustment seat (24), and a baffle (25) is welded on the upper surface; The workbench driving device (7) comprises: a rack (701), a reduction motor (702), and a gear (703); the rack (701) is fixedly mounted on the lower surface of the auxiliary lower crosspiece (22) on both sides of the workbench frame (18), respectively; the gear (703) is fixedly mounted on the protruding end of the rotating shaft of the reduction motor (702) and should be able to maintain good meshing with the rack (701) over the entire length; the reduction motor (702) is fixedly mounted on the floor (17) of the container body; The workbench positioning device (8) comprises: a positioning plate (801), a cylinder (802), a cylinder bracket (803), a positioning pin (804), a sensor bracket (805), and a limit sensor (806); the positioning plate (801) is welded and fixed on the upper surface of the straight gear (27); the protruding end of the cylinder (802) serves as a positioning pin (804) and is movably matched with the positioning hole on the positioning plate (801); the cylinder (802) is fixed on the cylinder bracket (803); a sensor bracket (805) and a limit sensor (806) mounted on its upper surface are also arranged next to the cylinder bracket (803); the bottom ends of the cylinder bracket (803) and the sensor bracket (805) are fixed to the floor (17) of the container body; The environmental protection facility system comprises: a welding fume purifier (13) and a welding fume and arc isolation cover (14).

2. The intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh according to claim 1 is characterized by: An electrical appliance control box (12) is fixedly mounted above the robot control box A (3) and the robot control box B (4), and a plurality of touch switches (16) for controlling related motors or electrical appliances are arranged on the surface of the electrical appliance control box (12).

3. The intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh according to claim 1 is characterized by: The flexible workbench A (5) and the flexible workbench B (6) have the same structural form and are arranged relative to each other. The length, width and height of the flexible workbench A (5) are all larger than those of the flexible workbench B (6). Therefore, when there is no welding operation, most of the flexible workbench B (6) can be stored inside the flexible workbench A (5) to achieve overlapping placement.

4. The intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh according to claim 1 is characterized in that: The intermediate welding fixture (19) comprises an intermediate plate (191), a large bolt (192), an intermediate longitudinal positioning block (193), an intermediate transverse positioning block (194), a small bolt A (195), and a workpiece clamp A (196); the intermediate plate (191) is fixed to the workbench frame (18) by using large bolts (192) at four corners; a plurality of intermediate longitudinal positioning blocks (193) and intermediate transverse positioning blocks (194) are installed and welded on the upper surface of the intermediate plate (191) according to the specifications of the workpiece; a plurality of grooves for movably cooperating with the workpiece are provided on the intermediate longitudinal positioning blocks (193) and the intermediate transverse positioning blocks (194); and one or more workpiece clamps A (196) are fixedly installed on the intermediate plate (191) by using small bolts A (195) next to the intermediate longitudinal positioning blocks (193) and the intermediate transverse positioning blocks (194).

5. The intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh according to claim 1 is characterized by: The left welding fixture (20) comprises an end plate (201), a positioning protrusion (202), a manual fastener (203), a buckle (204), an end longitudinal positioning block (205), an end transverse positioning block (206), a small bolt B, and a workpiece clamp B (208); the end plate (201) is provided with four notches for active cooperation with four positioning protrusions (202) welded and fixed on the workbench frame (18), and is connected to the end plate through a plurality of manual fasteners (203) fixedly mounted on the side of the upper crossbar (26) and the manual fasteners (203) mounted on the end plate. The end plate (201) is connected by a buckle (204) on the side; a plurality of end longitudinal positioning blocks (205) and end transverse positioning blocks (206) are installed and welded on the upper surface of the end plate (201) according to the specifications of the workpiece, and a plurality of grooves for active cooperation with the workpiece are provided on the end longitudinal positioning blocks (205) and the end transverse positioning blocks (206); beside the end longitudinal positioning blocks (205) and the end transverse positioning blocks (206), a plurality of workpiece clamps B (208) are fixedly installed on the end plate (201) by small bolts B.

6. The intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh according to claim 1 is characterized by: The flexible workbench A (5) and the flexible workbench B (6) are respectively provided with two sets of workbench driving devices (7).

7. The intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh according to claim 1 is characterized by: The flexible workbench A (5) and the flexible workbench B (6) are respectively provided with two sets of workbench positioning devices (8), and the two sets of workbench positioning devices (8) are symmetrically installed on the inner side of the straight block (27) of the workbench frame (18).

8. The intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh according to claim 1 is characterized by: The welding fume purifier (13) is bolted to the top of one end of the container body (9), and the welding fume and arc isolation cover (14) is installed on the top of the two inner side walls of the container body (9). The retraction and extension are controlled by the corresponding touch switch (16) on the electrical control box (12).

9. The intelligent integrated welding workstation for high-speed railway box girder pipeline positioning mesh according to claim 1 is characterized by: The data acquisition and display system (10) comprises a robot control box A (3), a robot control box B (4), a programmable controller, an intelligent electronic signboard and a server. The programmable controller and the intelligent electronic signboard are fixedly mounted at the middle position of the top of the container body (9). The output end of the programmable controller is connected to the input end of the intelligent electronic signboard, the output end of the intelligent electronic signboard is connected to the server, and the input end of the programmable controller is connected in parallel with the robot control box A (3), the robot control box B (4) and the electrical control box (12).

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