Powder inner spraying device for straight pipe with elbow

Abstract

The utility model relates to a powder internal spraying device for a straight pipe with an elbow, which comprises an elbow end powder recoverer, a straight pipe end powder recoverer, a workpiece trolley, the straight pipe with the elbow and a spraying unit, the straight pipe with the elbow is placed on the workpiece trolley, the elbow end powder recoverer is mounted at the elbow end of the straight pipe with the elbow, and the straight pipe end powder recoverer is mounted at the straight pipe end of the straight pipe with the elbow. The straight pipe end powder recoverer is installed at the straight pipe end of the straight pipe with the elbow, the position and posture of the spraying unit are adjusted to be aligned with the straight pipe with the elbow, and the spraying unit stretches into the straight pipe with the elbow to conduct spraying. Compared with the prior art, the device has the advantages that the bent pipe end powder recoverer and the straight pipe end powder recoverer are arranged, redundant powder can be collected in the bent pipe spraying process, meanwhile, the spraying unit can be automatically aligned to the center of a straight pipe with an elbow, and spraying is convenient.

Description

Technical Field

[0001] This utility model relates to the field of internal spraying technology; in particular, it relates to a powder internal spraying device for a straight pipe with an elbow. Background Technology

[0002] Powder coating technology is widely used in industrial manufacturing, especially for the corrosion protection and decoration of the inner surfaces of pipes and containers. Traditional internal coating processes mostly use straight-line spraying equipment, which is effective for treating the inner walls of straight pipes, but has significant limitations when dealing with pipes with bends. The special geometry of bends makes it difficult for powder coating to adhere evenly, easily leading to problems such as coating accumulation, exposed substrate, or uneven thickness, affecting corrosion protection performance and service life.

[0003] Existing solutions include segmented disassembly and spraying, and flexible hose extension spraying, but the former increases process complexity and labor costs, while the latter reduces powder delivery efficiency due to friction on the inner wall of the hose and makes it difficult to accurately control the spraying trajectory. In addition, changes in the radius of curvature at bends place higher demands on the dynamic adjustment of spraying parameters, and traditional equipment lacks adaptive adjustment capabilities, resulting in insufficient coating quality stability.

[0004] Utility model patent CN211070588U discloses a fully automatic bent pipe powder coating device, including a workbench, a powder coating unit, and a powder recovery unit. The workbench is used to place the heated bent pipe to be coated. The powder coating unit includes a traveling assembly, a powder supply assembly, and a high-temperature resistant flexible tube powder spray gun mounted on the traveling assembly. The high-temperature resistant flexible tube powder spray gun includes a high-temperature resistant flexible tube, a powder nozzle with multiple nozzles at the end of the high-temperature resistant flexible tube, multiple sets of centering guide wheels wrapped around the outside of the high-temperature resistant flexible tube, and multiple powder supply pipes inside the high-temperature resistant flexible tube. One end of each powder supply pipe is connected to a corresponding nozzle, and the other end is connected to the powder supply assembly. The powder recovery unit is located on both sides of the workbench and is used to collect excess powder during the powder coating process. Although this patent can achieve bent pipe powder coating, it lacks a device for automatically aligning the coating unit with the bent pipe and cannot adjust the position in real time.

[0005] Therefore, providing a nozzle device that can adjust the alignment position in real time is an urgent problem to be solved. Utility Model Content

[0006] The purpose of this invention is to overcome the defects of the prior art and provide a powder internal spraying device for a straight pipe with an elbow.

[0007] The objective of this utility model can be achieved through the following technical solutions:

[0008] According to one aspect of the present invention, a powder coating device for an internal spraying of a straight pipe with an elbow is provided, comprising a powder collector at the elbow end, a powder collector at the straight pipe end, a workpiece carriage, a straight pipe with an elbow, and a spraying unit. The straight pipe with an elbow is placed on the workpiece carriage, the powder collector at the elbow end is installed at the elbow end of the straight pipe with an elbow, the powder collector at the straight pipe end is installed at the straight pipe end of the straight pipe with an elbow, the spraying unit is adjusted to align with the straight pipe with an elbow, and the spraying unit extends into the straight pipe with an elbow to perform spraying.

[0009] As a preferred technical solution, the spraying unit includes a powder rotary cup, a copper material tube, a spraying motor, a tank chain, a powder supply pipe, a lifting unit, and a spraying trolley. The powder supply pipe is installed in the tank chain and communicates with the spraying trolley. The spraying motor is installed on the tank chain and communicates with the powder rotary cup. The copper material tube is installed on the spraying motor and communicates with both the powder rotary cup and the powder supply pipe. The tank chain is placed on the lifting unit and connected to the spraying trolley.

[0010] As a preferred technical solution, the lifting unit includes a lifter and a placement plate, the placement plate being mounted on the lifter and the tank chain being placed on the placement plate.

[0011] As a preferred technical solution, the powder rotary cup and the straight pipe with elbow are aligned at their centers.

[0012] As a preferred technical solution, the spraying trolley includes a powder spray gun and a frame, the powder spray gun is mounted on the frame, the powder spray gun is connected to the tank chain and communicates with the hose.

[0013] As a preferred technical solution, the painting trolley further includes a base, wheels, and guide rails. The base is mounted on the frame, the wheels are mounted on the base, and the wheels are mounted on the guide rails.

[0014] As a preferred technical solution, the spraying trolley also includes a spray gun column for the powder spray gun, the spray gun column includes a transverse rotating shaft, and the powder spray gun is placed on the transverse rotating roller of the spray gun column.

[0015] As a preferred technical solution, the spraying trolley also includes a venturi tube, a stainless steel powder box, an air storage pipe, and an air circuit control unit. The stainless steel powder box, the air storage pipe, and the air circuit control unit are all mounted on the frame. The venturi tube is connected to the powder supply pipe and the air circuit control unit respectively. The powder supply pipe is connected to the powder spray gun. The air circuit control unit is connected to the air storage pipe and the stainless steel powder box respectively.

[0016] As a preferred technical solution, the painting trolley further includes a first air collecting block and a second air collecting block, which are installed on the air circuit control unit.

[0017] As a preferred technical solution, the spraying trolley further includes a dilution channel and a powder supply channel, both of which are installed on the air circuit control unit. The dilution channel is connected to the second gas collecting block and the Venturi tube, respectively, and the powder supply channel is connected to the first gas collecting block and the Venturi tube, respectively.

[0018] Compared with the prior art, the present invention has the following beneficial effects;

[0019] 1. This utility model is equipped with a powder collector at the bent end and a powder collector at the straight end, which can collect excess powder during the spraying process of the bent pipe. At the same time, the spraying unit can automatically align with the center of the straight pipe with the bend, which facilitates spraying.

[0020] 2. This utility model is equipped with a lifting unit, which can adjust the position of the metal tank chain so that it is always aligned with the center of the straight pipe with bend, and can adapt well to straight pipes with bends of different sizes.

[0021] 3. This utility model is equipped with a dilution channel, which can dilute the powder supply gas containing powder according to the actual situation, reduce the powder concentration, and avoid waste.

[0022] 4. This utility model is equipped with a metal tank chain. While ensuring flexibility, the tank chain has higher strength and can prevent the pipeline from shaking under spraying pressure during the spraying process. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0024] Figure 2 This is a schematic diagram of the installation of the spraying unit and the straight pipe with elbow of this utility model;

[0025] Figure 3 This is a schematic diagram of the structure of the painting cart of this utility model;

[0026] Figure 4 This is a front view of the overall structure of this utility model;

[0027] Figure 5 This is a left view of the overall structure of this utility model;

[0028] Figure 6 This is a right view of the overall structure of this utility model;

[0029] Figure 7 This is a top view of the overall structure of this utility model;

[0030] Figure 8 This is a schematic diagram of the spraying unit and the alignment of the straight pipe with the elbow of this utility model.

[0031] Figure 9 This is a front view of the painting cart of this utility model;

[0032] Figure 10 This is a right view of the painting cart of this utility model;

[0033] Figure 11 This is a left view of the painting cart of this utility model;

[0034] Figure 12 This is a first-view structural schematic diagram of the painting cart of this utility model;

[0035] Figure 13 This is a schematic diagram of the painting cart of this utility model from another perspective.

[0036] Figure 14 This is a top view of the nozzle carriage of this utility model;

[0037] 1. Powder collector at elbow end; 2. Powder collector at straight pipe end; 3. Workpiece trolley; 4. Straight pipe with elbow; 5. Powder rotary cup; 6. Copper material pipe; 7. Spraying motor; 8. Metal tank chain; 9. Lifting unit; 10. Electrical control cabinet; 11. Powder spray gun; 12. Spray gun column; 13. Powder supply pipe; 14. Venturi tube; 15. Stainless steel powder box; 16. Air pressure regulating valve; 17. First air collection block; 18. Second air collection block; 19. Cable plastic drag chain; 20. Base; 21. Reducer; 22. Wheel; 23. Air pressure knob; 24. First pneumatic ball valve; 25. Air tank; 26. Second pneumatic ball valve; 27. Air tank pressure gauge; 28. Powder supply pressure gauge; 29. ​​Dilution pressure gauge; 30. Guide rail;

[0038] 31. Air inlet of the gas storage tank; 32. Pressure gauge port of the gas storage tank; 33. Air inlet of the first pneumatic ball valve on the gas storage tank; 34. Air inlet of the solenoid valve of the first pneumatic ball valve on the gas storage tank; 35. Air inlet of the solenoid valve of the second pneumatic ball valve on the gas storage tank; 36. Air inlet of the second pneumatic ball valve on the gas storage tank; 37. Air inlet of the pressure regulating valve on the gas storage tank; 38. Air inlet of the stainless steel powder box; 39. Air outlet of the pressure regulating valve; 40. Air inlet of the pressure regulating valve; 41. Air inlet of the first pneumatic ball valve; 42. Air outlet of the first pneumatic ball valve; 43. Air inlet of the solenoid valve of the first pneumatic ball valve; 44. Air outlet of the second pneumatic ball valve; 45. Air inlet of the second pneumatic ball valve; 46. Air inlet of the solenoid valve of the second pneumatic ball valve; 47. 48. Venturi tube powder outlet; 49. Venturi tube powder supply gas inlet; 50. Venturi tube dilution gas inlet; 51. Second pneumatic ball valve inlet of the second gas collector; 52. First pneumatic ball valve inlet of the first gas collector; 53. Powder supply gas outlet of the first gas collector; 54. Dilution gas outlet of the second gas collector; 55. Powder supply gas inlet of the pressure knob; 56. Powder supply pressure gauge outlet of the pressure knob; 57. Powder supply pressure gauge inlet; 58. Dilution gas outlet of the pressure knob; 59. Dilution gas inlet of the pressure knob; 60. Dilution pressure gauge outlet of the pressure knob; 61. Dilution pressure gauge inlet. Detailed Implementation

[0039] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present utility model.

[0040] With the development of industrial automation and intelligent manufacturing, the market demand for efficient and precise internal spraying equipment is becoming increasingly urgent. Developing an adaptive spraying device that can adapt to complex pipeline structures requires solving key technical challenges such as adaptive elbow curvature, dynamic powder conveying control, and rapid one-time molding, so as to achieve uniform coverage and precise thickness control of the powder coating, thereby improving production efficiency and product quality.

[0041] This invention enables rapid internal powder coating of a straight pipe with bends placed horizontally on a workpiece carriage, with powder being collected at both ends of the pipe. The coating process is highly automated, saving manpower and significantly improving production efficiency.

[0042] Example 1

[0043] like Figures 1-8As shown, a powder coating device for a straight pipe with an elbow includes a powder collector 1 at the elbow end, a powder collector 2 at the straight pipe end, a workpiece carriage 3, a straight pipe with an elbow 4, and a coating unit. The straight pipe with an elbow 4 is placed on the workpiece carriage 3. The powder collector 1 at the elbow end is installed at the elbow end of the straight pipe with an elbow 4, and the powder collector 2 at the straight pipe end is installed at the straight pipe end of the straight pipe with an elbow 4. The coating unit is adjusted to align with the straight pipe with an elbow 4, and the coating unit extends into the straight pipe with an elbow 4 to perform coating.

[0044] The spraying unit includes a powder rotary cup 5, a copper feed tube 6, a spraying motor 7, a tank chain 8, a powder supply pipe 13, a lifting unit, and a spraying trolley. The powder supply pipe 13 is installed in the tank chain 8 and communicates with the spraying trolley. The spraying motor 7 is installed on the tank chain 8 and communicates with the powder rotary cup 6. The copper feed tube 6 is installed on the spraying motor 7 and communicates with both the powder rotary cup 5 and the powder supply pipe 13. The tank chain 8 is placed on the lifting unit and connected to the spraying trolley. The lifting unit includes a lifter 9 and a placement plate. The placement plate is installed on the lifter 9, and the tank chain 8 is placed on the placement plate.

[0045] The powder rotary cup 5 and the straight pipe with elbow 4 are aligned at their centers.

[0046] In this embodiment, the operating principle of the device is as follows: The workpiece carriage 3 transports the straight pipe 4 with bends, whose surface has reached the set temperature, to the powder spraying station. Then, the suction hoods of the powder collector 1 at the bend end and the powder collector 2 at the straight pipe end are adjusted. These suction hoods and pipelines have a certain rigidity and can be placed vertically, horizontally, or vertically at both ends of the straight pipe 4 with bends. The suction hood of the powder collector 1 at the bend end needs to be vertically aligned with the pipe opening at the bend end. It is mainly responsible for absorbing excess powder suspended inside the pipe during the spraying process. The powder absorption function of this suction hood plays an important role in the uniformity of the film thickness on the inner wall of the bend pipe. The suction hood of the powder collector 2 at the straight pipe end is placed on the upper part of the straight section and does not affect the movement of the spray gun. The purpose of this suction hood is to absorb the residual powder thrown out by the powder cup of the spray gun after the powder spraying is completed.

[0047] The copper material tubes 6 are evenly distributed along the axial direction of the spraying motor 7 on its outer surface and are fixed by a bracket. Each copper material tube 6 is 150mm long, with one end machined into a spoon shape, which extends into the powder swivel cup 5 as a powder outlet. Powder is thrown into the powder swivel cup 5 along the spoon opening; the other end is connected to the powder supply tube 13 (flexible tube). The spraying motor 7 is installed on the port of the tank chain 8. The electrical wires of the spraying motor 7, together with the powder supply tubes, pass through the inside of the tank chain 8 and the straight pipe of the spray gun, and are connected to the powder supply system and electrical system at the powder supply trolley.

[0048] These two suction hoods ensure that any escaping powder is absorbed. The handwheel at the front of the lifting unit is then manually cranked to adjust the metal tank chain 8 up and down, thereby adjusting the powder spray gun 11 up and down to ensure that the powder cup 5 on the powder spray gun 11 is centered on the straight pipe 4 with the bend. Multiple support wheels on the tank chain 8 ensure good contact with the inner wall of the straight pipe 4 with the bend. Adjusting the distance between the wheels on both sides of the metal tank chain 8 at the front of the powder spray gun 11 ensures that the metal tank chain 8 can smoothly pass through the bend. The wheels are located on the left, right, and bottom sides of the tank chain 8, allowing for three-sided contact when the tank chain 8 enters the pipe, providing good support. The tank chain 8 can also be positioned in more directions. The lifting unit uses a dual-axis linkage screw auger 9.

[0049] The painting trolley includes a powder spray gun 11 and a frame. The powder spray gun 11 is mounted on the frame and is connected to the tank chain 8 and communicates with a hose.

[0050] The painting trolley also includes a base 20, wheels 22 and guide rails 30. The base 20 is mounted on the frame, the wheels 22 are mounted on the base 20 and the guide rails 30.

[0051] The spraying trolley also includes a spray gun column 12 for the powder spray gun 11. The spray gun column 12 includes a transverse rotating shaft, and the powder spray gun 11 is placed on the transverse rotating roller of the spray gun column 12.

[0052] The spraying trolley also includes a venturi tube 14, a stainless steel powder box 15, an air storage pipe 25, and an air circuit control unit. The stainless steel powder box 15, the air storage pipe 25, and the air circuit control unit are all mounted on the frame. The venturi tube 14 is connected to the powder supply pipe 13 and the air circuit control unit respectively. The powder supply pipe 13 is connected to the powder spray gun 11. The air circuit control unit is connected to the air storage pipe 25 and the stainless steel powder box 15 respectively.

[0053] The painting trolley also includes a first air collecting block 17 and a second air collecting block 18, which are installed on the air circuit control unit.

[0054] The spraying trolley also includes a dilution channel and a powder supply channel, both of which are installed on the air circuit control unit. The dilution channel is connected to the second gas collecting block 18 and the venturi tube 14, respectively, and the powder supply channel is connected to the first gas collecting block 17 and the venturi tube 14, respectively.

[0055] In this embodiment, the fluidization pressure, powder supply pressure, and dilution pressure of the stainless steel powder box 15 are set according to the diameter of the pipe. The spraying carriage is started, and the spraying carriage moves forward, driving the powder spray gun 11 into the straight pipe 4 with an elbow. When the powder rotary cup 5 extends completely out of the other end of the elbow, the spraying carriage stops moving forward. According to the characteristics of the straight pipe 4 with an elbow, the spraying carriage is set to a multi-stage speed for automatic reversal. At the beginning of the reversal spraying, it is at a high speed; when it reaches the middle of the pipe, it switches to a medium speed; and when it reaches about 1m from the pipe opening, it switches to a slow speed. This multi-stage speed setting is to ensure the uniformity of the overall film thickness of the straight pipe with an elbow. Spraying is started, and after the powder from the high-speed rotation of the powder rotary cup 5 is uniformly atomized, the spraying carriage reverses at multiple speeds until the powder rotary cup 5 is completely out of the straight pipe 4 with an elbow, and the spraying stops. The residual powder on the surface of the spray gun 11 and the lifting unit is then cleaned before the next straight pipe with an elbow is sprayed.

[0056] In this utility model, six Venturi tubes 14 are provided. The dilution channels are respectively connected to the second gas collecting block 18 and the dilution ports of the six Venturi tubes 14. The powder supply channels are respectively connected to the first gas collecting block 17 and the powder supply ports of the six Venturi tubes 14.

[0057] The internal spraying device contains 6 powder supply pipes 13, but the spraying trolley has reserved air passages for 8 powder supply pipes 13 so that when internal spraying larger pipes (outer diameter φ600mm or more), 8 more powder supply pipes can be installed on the spraying device to meet the powder supply requirements.

[0058] The first gas collecting block 17 and the second gas collecting block 18 are both gas collecting blocks with one inlet and eight outlets.

[0059] Example 2

[0060] like Figures 9-14As shown, the air circuit principle of this utility model is as follows: the spraying system receives air from the outside through the air inlet 31 of the air tank; the pressure gauge port 32 of the air tank serves as the system air pressure indicator; the air inlet 33 of the first pneumatic ball valve on the air tank is connected to the air inlet 45 of the second pneumatic ball valve, supplying air to the second pneumatic ball valve 26; the air inlet 34 of the first pneumatic ball valve's solenoid valve on the air tank is connected to the air inlet 46 of the second pneumatic ball valve's solenoid valve, supplying air to the second pneumatic ball valve 26; the air inlet 35 of the second pneumatic ball valve's solenoid valve on the air tank is connected to the air inlet 46 of the first pneumatic ball valve... The air inlet 43 of the electrically controlled valve is connected to supply air to the first pneumatic ball valve 24; the air inlet 36 of the second pneumatic ball valve on the air storage tank is connected to the air inlet 41 of the first pneumatic ball valve, supplying air to the first pneumatic ball valve 24; the air inlet 37 of the air pressure regulating valve on the air storage tank is connected to the air inlet 40 of the air pressure regulating valve, supplying air to the air pressure regulating valve 16; the air outlet 39 of the air pressure regulating valve is connected to the air inlet 38 of the stainless steel powder box, supplying air to the stainless steel powder box 15. The gas enters the fluidizing plate at the bottom of the powder box through the air inlet 38 of the stainless steel powder box, so that the powder in the powder box is... Uniform mixing and atomization; the outlet 42 of the first pneumatic ball valve is connected to the inlet 51 of the first pneumatic ball valve of the first gas collecting block, and the powder supply gas enters the first gas collecting block 17 through the outlet 42 of the first pneumatic ball valve; the outlet 52 of the powder supply gas of the first gas collecting block is connected to the inlet 55 of the powder supply gas of the pressure knob, the outlet 56 of the pressure knob is connected to the inlet 57 of the pressure gauge, and the outlet 54 of the pressure knob is connected to the inlet 48 of the venturi tube, and the powder supply gas from the first gas collecting block 17 enters... After setting the powder supply pressure using the air pressure knob on the powder supply pressure gauge, the powder supply gas enters the venturi tube powder supply gas inlet 48. The venturi tube powder outlet 47 is connected to the powder supply pipe 13, which is a flexible tube. The other end of the powder supply pipe 13 is connected to the copper material pipe 6. The copper material pipe 6, which is evenly installed around the spraying motor, propels the powder and gas mixture into the spraying rotary cup 5. The powder passes through the high-speed rotating spraying rotary cup 5 and is evenly ejected from the small hole on the outer cylindrical surface of the rotary cup, coating the inner surface of the tube.

[0061] The outlet 44 of the second pneumatic ball valve is connected to the inlet 50 of the second pneumatic ball valve of the second gas collector. The diluent gas enters the second gas collector 18 through the outlet 44 of the second pneumatic ball valve. The outlet 53 of the diluent gas of the second gas collector is connected to the inlet 59 of the diluent gas of the pressure knob. The outlet 60 of the diluent pressure gauge of the pressure knob is connected to the inlet 61 of the diluent pressure gauge. The outlet 58 of the diluent gas of the pressure knob is connected to the inlet 49 of the diluent gas of the venturi tube. The diluent gas coming out of the second gas collector 18 enters the diluent pressure gauge 29. After the diluent pressure is set by the pressure knob, the diluent gas enters the inlet 49 of the venturi tube to dilute the powder supply gas containing powder after passing through the venturi tube 14.

[0062] The above gas path connection is only for one powder tube. The other five powder tubes are connected in the same way, which will not be repeated in this article. If two more powder tubes are added later, simply add two Venturi tubes to the stainless steel powder box 15 and connect them in the same way.

[0063] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A powder coating device for use with a straight pipe with an elbow, characterized in that, The device includes a bent-end powder collector (1), a straight-end powder collector (2), a workpiece carriage (3), a straight pipe with an elbow (4), and a spraying unit. The straight pipe with an elbow (4) is placed on the workpiece carriage (3). The bent-end powder collector (1) is installed at the bent end of the straight pipe with an elbow (4). The straight-end powder collector (2) is installed at the straight end of the straight pipe with an elbow (4). The spraying unit is adjusted to align with the straight pipe with an elbow (4). The spraying unit extends into the straight pipe with an elbow (4) to perform spraying.

2. The powder internal spraying device for a straight pipe with an elbow according to claim 1, characterized in that, The spraying unit includes a powder rotary cup (5), a copper material tube (6), a spraying motor (7), a tank chain (8), a powder supply pipe (13), a lifting unit, and a spraying trolley. The powder supply pipe (13) is installed in the tank chain (8) and communicates with the spraying trolley. The spraying motor (7) is installed on the tank chain (8) and communicates with the powder rotary cup (5). The copper material tube (6) is installed on the spraying motor (7) and communicates with both the powder rotary cup (5) and the powder supply pipe (13). The tank chain (8) is placed on the lifting unit and connected to the spraying trolley.

3. A powder internal spraying device for a straight pipe with an elbow, as described in claim 2, is characterized in that... The lifting unit includes a lifter (9) and a placement plate, the placement plate being mounted on the lifter (9), and the tank chain (8) being placed on the placement plate.

4. A powder internal spraying device for a straight pipe with an elbow, as described in claim 3, is characterized in that... The powder rotary cup (5) and the straight tube with elbow (4) are aligned at their centers.

5. A powder internal spraying device for a straight pipe with an elbow, as described in claim 2, characterized in that, The painting trolley includes a powder spray gun (11) and a frame. The powder spray gun (11) is mounted on the frame and is connected to the tank chain (8) and communicates with a hose.

6. A powder internal spraying device for a straight pipe with an elbow, as described in claim 5, is characterized in that... The painting trolley also includes a base (20), wheels (22) and a guide rail (30). The base (20) is mounted on the frame, the wheels (22) are mounted on the base (20), and the wheels (22) are mounted on the guide rail (30).

7. A powder internal spraying device for a straight pipe with an elbow, as described in claim 5, characterized in that, The spraying trolley also includes a spray gun column (12) for the powder spray gun (11), the spray gun column (12) includes a transverse rotating shaft, and the powder spray gun (11) is placed on the transverse rotating roller of the spray gun column (12).

8. A powder internal spraying device for a straight pipe with an elbow, as described in claim 2, characterized in that, The spraying trolley also includes a venturi tube (14), a stainless steel powder box (15), an air storage pipe (25), and an air circuit control unit. The stainless steel powder box (15), the air storage pipe (25), and the air circuit control unit are all mounted on the frame. The venturi tube (14) is connected to the powder supply pipe (13) and the air circuit control unit respectively. The powder supply pipe (13) is connected to the powder spray gun (11). The air circuit control unit is connected to the air storage pipe (25) and the stainless steel powder box (15) respectively.

9. A powder internal spraying device for a straight pipe with an elbow, as described in claim 8, characterized in that, The painting trolley also includes a first air collecting block (17) and a second air collecting block (18), which are mounted on the air circuit control unit.

10. A powder internal spraying device for a straight pipe with an elbow, as described in claim 9, characterized in that, The spraying trolley also includes a dilution channel and a powder supply channel. Both the dilution channel and the powder supply channel are installed on the air circuit control unit. The dilution channel is connected to the second gas collecting block (18) and the venturi tube (14) respectively. The powder supply channel is connected to the first gas collecting block (17) and the venturi tube (14) respectively.

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