Plastic coating device and method applied to inner wall of metal pipe

Abstract

The invention provides a plastic coating device and method applied to the inner wall of a metal pipe, and particularly relates to the technical field of plastic coating of the inner wall of the pipe. The device comprises a pit, a PLC (Programmable Logic Controller) and a device body, the device body comprises a base installed next to the ground on the rear side of a pit. A mounting vertical frame is arranged on the side, close to the pit, of the top of the base. A rotary disc is rotationally arranged on the side, away from the base, of the mounting vertical frame. A connecting disc is fixed to the side, close to the pit, of the rotary disc. A stock bin box is arranged in the pit; a fixed table is arranged at the top of the stock bin box; the rear end of the fixing table is fixed to the bottom of the front end of the connecting disc. The stock bin box rotates clockwise or anticlockwise by 360 degrees along with the rotating disc through the connecting disc. Compared with a traditional plastic coating process and equipment, the requirement for cleanliness of the inner surface of the metal pipe is low, plastic coating materials are convenient to recycle, the plastic coating effect is uniform, and the plastic coating process can be suitable for the plastic coating process of pipes of multiple sizes and multiple shapes.

Description

Technical Field

[0001] The patent of this invention relates to the technical field of plastic coating on the inner wall of pipes, and specifically to a plastic coating device and method applied to the inner wall of metal pipes. Background Art

[0002] Traditional metal pipe inner wall plastic coating processes mostly fall into the following four categories, each with varying drawbacks: Process 1, manual spraying: This relies on operator experience, resulting in uneven coating thickness and prone to dripping or missing coatings; Process 2, electrostatic adsorption: This requires high pipe inner wall cleanliness, and incomplete pretreatment can easily lead to poor coating adhesion; Process 3, plastic dipping: This has a low plastic powder utilization rate (only 30%-50%) and imposes significant restrictions on pipe shape and size; Process 4, curing: Traditional hot air curing consumes a lot of energy and is prone to coating embrittlement due to temperature fluctuations. Furthermore, existing inner wall powder spraying devices also suffer from issues such as uneven coating caused by eccentric pipe rotation and difficulty recovering excess plastic powder.

[0003] Therefore, there is an urgent need for an efficient, energy-saving, and adaptable pipe inner wall plastic coating equipment for various pipe diameters and shapes. Summary of the Invention

[0004] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a device and method for coating the inner wall of a metal pipe with plastic. The specific technical solution is as follows:

[0005] A plastic coating device for the inner wall of a metal pipe comprises a pit, a PLC controller and a device body; the device body comprises a base mounted on the ground immediately behind the pit; a mounting stand is provided on the top of the base close to the pit; a turntable is rotatably provided on the side of the mounting stand away from the base; a connecting disk is fixed to the side of the turntable close to the pit; a silo box is provided in the pit; a fixing platform is provided on the top of the silo box; the rear end of the fixing platform is fixed to the front bottom of the connecting disk; the silo box rotates 360° clockwise or counterclockwise along with the turntable via the connecting disk.

[0006] Preferably, a servo motor is installed on the top of the base, and the output shaft of the servo motor is connected to the central axis of the turntable through a reducer.

[0007] Preferably, a pipe fixing opening is provided in the middle of the fixing platform; the silo box is provided with a silo opening corresponding to the pipe fixing opening, and a silo door is provided at the silo opening, and the opening and closing of the silo door is controlled by a pneumatic cylinder or an oil cylinder.

[0008] Preferably, at least two independently controlled hydraulic clamps are arranged at equal intervals on the top of the fixing platform around the pipe fixing opening.

[0009] Preferably, the servo motor, air cylinder or oil cylinder are all electrically connected to a PLC controller.

[0010] Preferably, the connecting plate includes a support frame and an arc-shaped pipe frame installed on the edge of the support frame; a counterweight fixing plate is provided on the top of the side of the support frame away from the fixed platform.

[0011] Also preferably, a ladder is provided on the left or right side of the mounting stand.

[0012] Also preferably, the plastic coating material in the silo box is one of linear low-density polyethylene powder, high-density polyethylene, polypropylene or polytetrafluoroethylene.

[0013] Further preferably, the device also includes a plurality of sealing plates that match the diameter of the metal pipe flange, a plurality of pipe fixing port adjustment plates and a plurality of C-type clamps.

[0014] A method for coating the inner wall of a metal pipe with plastic, using the above-mentioned plastic coating device, specifically comprises the following steps:

[0015] S1 Sandblast the metal pipe to be coated with plastic to remove the surface oxide layer and blow away the surface residue with compressed air;

[0016] S2 puts the surface pretreated metal pipe into the heating furnace and heats it to the melting temperature of the plastic coating material in the silo box, ensuring that the temperature difference does not exceed ±10℃;

[0017] S3 Select the pipe fixing port adjustment plate and plugging plate that match the diameter of the metal pipe flange, and place the pipe fixing port adjustment plate at the pipe fixing port;

[0018] S4 uses lifting equipment to align one of the pipe end flanges of the heated metal pipe with the pipe fixing adjustment plate and adjusts the hydraulic clamp to firmly fix the metal pipe at the pipe fixing port; then uses C-clamps to seal the sealing plate and the other pipe end flanges of the metal pipe; and determines whether to install a counterweight block on the counterweight fixing plate based on the weight of the metal pipe to ensure that there is no imbalance during rotation;

[0019] S5 opens the device. In the initial state, the silo box is located in the pit and the silo door is closed. The connecting disk rotates clockwise through the turntable. When the silo box rotates to the highest point, the PLC controller controls the air cylinder or oil cylinder to open the silo door, and the plastic-coated material in the silo box enters the inner cavity of the metal pipe. The first silo door opening time lasts for 5 to 15 seconds to ensure that the plastic-coated material can completely fill the inner cavity of the metal pipe; then the silo door is closed, and the connecting disk continues to rotate clockwise to carry out the inner wall plastic coating process; when the silo box rotates again to a position 10° close to the highest point, the silo door opens. When the silo box rotates 10° away from the highest point, the silo door automatically closes, completing one filling of the inner cavity of the metal pipe. After that, the material is replenished every time it rotates one circle to ensure that the plastic-coated material in the inner cavity is always filled;

[0020] S6 keeps rotating clockwise for 3 to 5 turns until the silo box returns to the lowest point in the pit, ensuring that the inner wall of the metal pipe is completely covered with the plastic coating material, thus ending the filling and plastic coating stage;

[0021] S7 enters the plastic coating material recovery stage: the connecting plate drives the silo box to rotate counterclockwise and then clockwise for 2 to 4 turns each. Whenever the silo box rotates to a position close to the lowest point of 60 degrees, the silo door opens. When the silo box rotates 60 degrees away from the lowest point, the silo door automatically closes, allowing the plastic coating material in the inner cavity of the metal pipe to be recovered into the silo box;

[0022] S8: The metal pipe with the inner wall plastic coating is removed and its surface temperature is measured with a temperature measuring pen. If it is lower than the melting temperature of the plastic coating material, a handheld heating gun is used to perform a secondary heating treatment on it to further fuse the plastic coating material and the inner wall of the metal pipe.

[0023] S9 performs water cooling on the metal pipe after secondary fusion in S8;

[0024] S10 grinds the end face of the metal pipe connected to the pipe fixing adjustment plate and detects the thickness of the end face along the circumference, with an allowable error of ±0.5mm;

[0025] S11 performs an electric spark test to check if there are any defects in the plastic coating and perform repairs;

[0026] S12 performs sandblasting, painting and packaging on the outer surface of metal pipes.

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention requires a lower cleanliness level for the inner surface of the metal pipe than the general coating requirement, and it only needs to meet Sa2.0 or above;

[0029] 3. The coating of the present invention is uniform and will not cause sagging or missing coating problems;

[0030] 4. The present invention facilitates the recycling of residual plastic coating materials, effectively increasing the reuse rate of plastic powder;

[0031] 5. The present invention can be applied to the inner wall plastic coating requirements of metal pipes of various shapes and sizes;

[0032] 6. The present invention does not require repeated heating and can effectively avoid the problem of coating embrittlement caused by temperature fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings constituting the description of the present invention are used to provide further understanding of the present application and do not constitute an improper limitation to the present application.

[0034] Figure 1 It is a front cross-sectional view of the present invention;

[0035] Figure 2 is a side sectional view of the present invention;

[0036] Figure 3 A top cross-sectional view of the present invention

[0037] In the figure, 1-pit; 2-base; 3-servo motor; 4-reducer; 5-turntable; 6-arc pipe rack; 7-silo box; 701-fixed platform; 7011-pipe fixing port; 8-hydraulic clamp; 9-mounting stand; 10-support frame; 1001-counterweight fixing plate; 11-ladder. DETAILED DESCRIPTION

[0038] The specific implementation of a plastic coating device and method for the inner wall of a metal pipe provided by the present invention is further described in conjunction with the accompanying drawings and embodiments.

[0039] like Figure 1-3 As shown, a plastic coating device for the inner wall of a metal pipe includes a pit 1, a PLC controller, and a device body. The device body includes a base 2 installed on the ground close to the rear side of the pit 1; a mounting stand 9 is provided on the side of the base 2 close to the pit 1; a turntable 5 is rotatably provided on the side of the mounting stand 9 close to the pit 1; a connecting disk is fixed on the side of the turntable 5 away from the mounting stand 9. A silo box 7 is provided in the pit 1; a fixed platform 701 is provided on the top of the silo box 7; the rear end of the fixed platform 701 is fixed to a position near the bottom of the front end of the connecting disk. When in use, the silo box 7 rotates 360° clockwise or counterclockwise along with the turntable 5 through the connecting disk.

[0040] Preferably, a servo motor 3 is installed on the top of the base 2 , and the output shaft of the servo motor 3 is connected to the central axis of the turntable 5 through a reducer 4 , thereby realizing the rotation of the turntable 5 .

[0041] Preferably, a pipe fixing opening 7011 is provided in the middle of the top wall of the fixing platform 701; the silo box 7 is provided with a silo opening corresponding to the position of the pipe fixing opening 7011, and a silo door is provided at the silo opening, and the opening and closing of the silo door is controlled by a pneumatic cylinder or an oil cylinder (not shown in the figure).

[0042] Preferably, the silo box 7 is filled with a plastic powder selected from linear low-density polyethylene powder (LLDPE), high-density polyethylene (HDPE), polypropylene (PP) or polytetrafluoroethylene (PTFE), which is used for coating the inner wall of the pipe.

[0043] Preferably, the top wall of the fixing platform 701 is provided with at least two independently controlled hydraulic clamps 8 around the pipe fixing port 7011 (the specific number of hydraulic clamps is determined according to the pipe diameter size, which is not further limited to the present invention here), which are used to firmly fix the metal pipe to be plastic-coated on the device.

[0044] Preferably, the servo motor 3, air cylinder or oil cylinder are all controlled and operated by a PLC controller.

[0045] Preferably, the connecting plate includes a support frame 10 and an arc-shaped pipe support 6 mounted on the edge of the support frame 10. To prevent rotational imbalance caused by heavy pipes, a counterweight fixing plate 1001 is provided on the top of the support frame 10, away from the fixed platform 701. If the metal pipes are heavy, a counterweight block is required on the counterweight fixing plate 1001.

[0046] In order to facilitate operators to seal the pipe openings of large-sized pipes, a ladder 11 is provided on one of the left or right sides of the mounting stand 9 .

[0047] Further preferably, the device also includes a number of sealing plates that match the diameter of the flange of the metal pipe to be plastic-coated, a number of pipe fixing port adjustment plates, and a number of C-clamp accessories for fixing the sealing plates.

[0048] The following is a detailed description of the specific working principle and coating process of the device, which specifically includes the following steps:

[0049] S1 Sandblast the metal pipe to be coated with plastic to remove the surface oxide layer and blow away the surface residue with compressed air;

[0050] S2 puts the surface pretreated metal pipe into the heating furnace and heats it to the melting temperature of the plastic coating material in the silo box (240℃~320℃, specifically set according to the type of plastic coating material), ensuring that the temperature difference does not exceed ±10℃;

[0051] S3 Select the pipe fixing port adjustment plate and plugging plate that match the diameter of the metal pipe flange, and place the pipe fixing port adjustment plate at the pipe fixing port;

[0052] S4 uses lifting equipment to align one of the pipe end flanges of the heated metal pipe with the pipe fixing adjustment plate and adjusts the hydraulic clamp to firmly fix the metal pipe at the pipe fixing port. At the same time, a C-clamp is used to seal the sealing plate and the other pipe end flanges of the metal pipe. The actual weight of the metal pipe determines whether a counterweight block needs to be installed on the counterweight fixing plate to ensure that there is no imbalance during rotation.

[0053] S5 opens the device (in the initial state, the silo box is in the pit and the silo door is closed), the connecting disk rotates clockwise through the turntable, and when the silo box rotates to the highest point, the PLC controller controls the servo motor to stop and controls the cylinder to open the silo door at the same time. A large amount of plastic coating material in the silo door enters the inner cavity of the metal pipe. In order to ensure that the plastic coating material completely fills the inner cavity of the pipe, the silo door is opened for 5 to 15 seconds (the specific feeding time is set according to the size, length and film thickness of the pipe); then the silo door closes automatically, and the connecting disk continues to rotate clockwise to coat the inner wall; in each subsequent round of the plastic coating process, the silo box opens when it rotates to a position 10° close to the highest point, and closes automatically when the silo box rotates 10° away from the highest point to feed the inner cavity of the metal pipe. Feeding is performed once each round of rotation to ensure that the plastic coating material in the inner cavity is always filled (it is worth noting that after the first round of plastic coating material filling is completed, each round of rotation will no longer stop, and only the switch state of the silo door needs to be changed).

[0054] S6 keeps the current state and rotates clockwise for 3 to 5 turns (the specific number of fusion turns is set according to the size, length and film thickness of the pipe) until the silo box returns to the initial position at the lowest point in the pit. The centrifugal force and gravity are used to ensure that the inner wall of the metal pipe is completely melted and covered with the plastic coating material. The plastic coating of the inner wall surface is completed and then the plastic coating material recovery stage begins.

[0055] The S7 connecting plate drives the silo box to rotate counterclockwise and then clockwise for 2 to 4 turns each (the specific number of recycling turns is set according to the size, length and film thickness of the pipe to ensure that the plastic coating material remaining in the inner cavity of the special-shaped pipe can be recycled as much as possible). Unlike the plastic coating process, during the recycling process, the silo box opens every time it rotates to a position close to the lowest point of 60 degrees. When the silo box rotates 60 degrees away from the lowest point, the silo box automatically closes, allowing the plastic coating material in the inner cavity of the metal pipe to be recycled into the silo box;

[0056] S8: The metal pipe with the inner wall plastic coating is removed and its surface temperature is measured with a temperature measuring pen. If it is lower than the melting temperature of the plastic coating material, a handheld heating gun is used to perform a secondary heating treatment on it to further fuse the plastic coating material and the inner wall of the metal pipe.

[0057] S9 performs water cooling treatment on the metal pipe after secondary fusion in S8 to improve the corrosion resistance, wear resistance and impact resistance of the coating;

[0058] S10 grinds the end face of the metal pipe connected to the pipe fixing adjustment plate and detects the thickness of the end face along the circumference, with an allowable error of ±0.5mm;

[0059] S11 performs an electric spark test to check whether the plastic coating layer has defects such as welding pores and protrusions and repairs the defects;

[0060] S12 performs subsequent treatments such as sandblasting, painting, and packaging on the outer surface of metal pipes according to user needs.

[0061] It is worth noting that the various rotation nodes, durations, control switches, etc. in the present invention can be realized through known existing electrical components, control programs and program instructions. The specific known control programs and software will not be elaborated here.

[0062] The present invention has a reasonable structure, is easy to operate, does not require repeated heating, is applicable to multiple pipe diameters, and the coating process does not rely on manual operation experience; the cleanliness requirement for the inner wall of the metal pipe is lower than the general coating requirement, and it only needs to meet Sa2.0 or above; compared with the traditional coating process, the improved coating method of the present invention has a uniform coating effect and will not cause problems such as sagging or missing coating; and the excess plastic powder material is easy to recycle, which effectively improves the reuse rate of the plastic powder.

[0063] In the present invention, the orientation or positional relationship indicated by terms such as "upper", "lower", "bottom", "top", etc. is based on the orientation or positional relationship shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationship of the various parts or elements of the present invention. They do not specifically refer to any part or element in the present invention and cannot be understood as limiting the present invention. Terms such as "connected" and "connect" should be understood in a broad sense, indicating that they can be fixedly connected, integrally connected, or detachably connected; they can be directly connected or indirectly connected through an intermediate medium. For relevant scientific research or technical personnel in this field, the specific meaning of the above terms in the present invention can be determined according to the specific circumstances, and they cannot be understood as limiting the present invention.

[0064] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A plastic coating device applied to the inner wall of a metal pipe, characterized in that: It includes a pit, a PLC controller and the device body; The device body includes a base installed on the ground close to the rear side of the pit; a mounting stand is provided on the top of the base close to the pit; a turntable is rotatably provided on the side of the mounting stand away from the base; a connecting plate is fixed on the side of the turntable close to the pit; A silo box is provided in the pit; a fixing platform is provided on the top of the silo box; the rear end of the fixing platform is fixed to the front bottom of the connecting plate; The silo box rotates 360° clockwise or counterclockwise along with the turntable via the connecting disk.

2. The plastic coating device for the inner wall of a metal pipe according to claim 1, characterized in that: A servo motor is installed on the top of the base, and the output shaft of the servo motor is connected to the central axis of the turntable through a speed reducer.

3. The plastic coating device for the inner wall of a metal pipe according to claim 2, characterized in that: A pipe fixing opening is provided in the middle of the fixing platform; The silo box is provided with a silo opening at a position corresponding to the pipe fixing opening, and a silo door is provided at the silo opening, and the opening and closing of the silo door is controlled by a pneumatic cylinder or an oil cylinder.

4. The plastic coating device for the inner wall of a metal pipe according to claim 3, characterized in that: At least two independently controlled hydraulic clamps are arranged at equal intervals on the top of the fixing platform around the pipe fixing opening.

5. The plastic coating device for the inner wall of a metal pipe according to claim 4, characterized in that: The servo motor, air cylinder or oil cylinder are all electrically connected to a PLC controller.

6. The plastic coating device for the inner wall of a metal pipe according to claim 5, characterized in that: The connecting plate includes a support frame and an arc-shaped pipe frame installed on the edge of the support frame; A counterweight fixing plate is provided on the top of one side of the support frame away from the fixing platform.

7. The plastic coating device for the inner wall of a metal pipe according to claim 1, characterized in that: A ladder is provided on the left or right side of the mounting frame.

8. The plastic coating device for the inner wall of a metal pipe according to claim 1, characterized in that: The plastic coating material in the silo box is one of linear low-density polyethylene powder, high-density polyethylene, polypropylene or polytetrafluoroethylene.

9. The plastic coating device for the inner wall of a metal pipe according to claim 6, characterized in that: It also includes several sealing plates that match the diameter of the metal pipe flange, several pipe fixing port adjustment plates and several C-type clamps.

10. A method for coating the inner wall of a metal pipe using the plastic coating device according to claim 9, characterized in that: The specific steps include: S1 Sandblast the metal pipe to be coated with plastic to remove the surface oxide layer and blow away the surface residue with compressed air; S2 puts the surface pretreated metal pipe into the heating furnace and heats it to the melting temperature of the plastic coating material in the silo box, ensuring that the temperature difference does not exceed ±10℃; S3 Select the pipe fixing port adjustment plate and plugging plate that match the diameter of the metal pipe flange, and place the pipe fixing port adjustment plate at the pipe fixing port; S4 uses lifting equipment to align one of the pipe end flanges of the heated metal pipe with the pipe fixing adjustment plate and adjusts the hydraulic clamp to firmly fix the metal pipe at the pipe fixing port; then uses C-clamps to seal the sealing plate and the other pipe end flanges of the metal pipe; and determines whether to install a counterweight block on the counterweight fixing plate based on the weight of the metal pipe to ensure that there is no imbalance during rotation; S5 opens the device. In the initial state, the silo box is located in the pit and the silo door is closed. The connecting disk rotates clockwise through the turntable. When the silo box rotates to the highest point, the PLC controller controls the air cylinder or oil cylinder to open the silo door, and the plastic-coated material in the silo box enters the inner cavity of the metal pipe. The first silo door opening time lasts for 5 to 15 seconds to ensure that the plastic-coated material can completely fill the inner cavity of the metal pipe; then the silo door is closed, and the connecting disk continues to rotate clockwise to carry out the inner wall plastic coating process; when the silo box rotates again to a position 10° close to the highest point, the silo door opens. When the silo box rotates 10° away from the highest point, the silo door automatically closes, completing one filling of the inner cavity of the metal pipe. After that, the material is replenished every time it rotates one circle to ensure that the plastic-coated material in the inner cavity is always filled; S6 keeps rotating clockwise for 3 to 5 turns until the silo box returns to its initial position at the lowest point in the pit, ensuring that the inner wall of the metal pipe is completely covered with the plastic coating material, thus ending the filling and plastic coating stage; S7 enters the plastic coating material recovery stage: the connecting plate drives the silo box to rotate counterclockwise and then clockwise for 2 to 4 turns each. Whenever the silo box rotates to a position close to the lowest point of 60 degrees, the silo door opens. When the silo box rotates 60 degrees away from the lowest point, the silo door automatically closes, allowing the plastic coating material in the inner cavity of the metal pipe to be recovered into the silo box; S8: The metal pipe with the inner wall plastic coating is removed and its surface temperature is measured with a temperature measuring pen. If it is lower than the melting temperature of the plastic coating material, a handheld heating gun is used to perform a secondary heating treatment on it to further fuse the plastic coating material and the inner wall of the metal pipe. S9 performs water cooling on the metal pipe after secondary fusion in S8; S10 grinds the end face of the metal pipe connected to the pipe fixing adjustment plate and detects the thickness of the end face along the circumference, with an allowable error of ±0.5mm; S11 performs an electric spark test to check if there are any defects in the plastic coating and perform repairs; S12 performs sandblasting, painting and packaging on the outer surface of metal pipes.

Images