A method for controlling the pickling of oxide layer on the inner wall of a composite steel pipe

Abstract

The present invention belongs to the field of surface treatment technology and discloses a method for controlling the pickling of an oxide layer on the inner wall of a composite steel pipe, comprising the following steps: (1) providing a nozzle having a conical nozzle at one end, wherein the nozzle can move axially back and forth in the composite steel pipe with the nozzle and can rotate circumferentially; (2) placing the composite steel pipe to be cleaned horizontally and manually placing the nozzle having a conical nozzle at the end into the composite steel pipe to be cleaned; (3) controlling the linear speed υ and circumferential rotation speed ρ of the nozzle in the composite steel pipe in the following manner: the linear speed of the nozzle is and the circumferential rotation speed of the nozzle is. The method of the present invention can achieve the purpose of automatically controlling the spray pickling of the inner wall, effectively overcome the shortcomings of the prior art, greatly improve the production line capacity, greatly reduce the labor load of workers, and improve the pickling quality of the composite steel pipe.

Description

Technical Field

[0001] The invention relates to the technical field of surface treatment, and in particular to a method for controlling pickling of an oxide layer on the inner wall of a composite steel pipe. Background Art

[0002] In the surface treatment process of composite steel pipes, acid is needed to remove the oxide layer on the inner wall of the steel pipe. Since the inner and outer layers of the composite steel pipe are made of different materials, the outer layer does not have the corrosion resistance required by the inner layer, so the composite steel pipe cannot be pickled by soaking in acid as a whole like ordinary steel pipes.

[0003] The pickling of the oxide layer on the inner wall of the composite steel pipe must be carried out by spraying the inner wall, so that the pickling agent is evenly distributed on the inner surface, but it cannot accumulate excessively and cause the liquid to flow out of the steel pipe and corrode the outer wall. Since the inner diameter of the steel pipe varies, the surface area is also different, which places extremely high demands on the uniformity and stability of the spray device.

[0004] The current common practice is to place the steel pipe horizontally and manually insert a rubber hose with a nozzle at one end into the inner cavity of the steel pipe from one end. While spraying the acid, the rubber hose is rotated manually, and the acid deposition on the inner wall surface is observed with the naked eye, and the nozzle is moved axially in time to adjust the spraying position.

[0005] However, since the length of the steel pipe can reach 20 meters, this method has great requirements on the operator's experience, vision, and endurance. The labor intensity of the workers is extremely high, and uneven spraying often causes acid to flow out and corrode the outer pipe or cause quality defects such as insufficient local pickling. Summary of the invention

[0006] The purpose of the present invention is to provide a method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe, so as to realize automatic control of the inner wall spray pickling, effectively overcome the shortcomings of the existing device, greatly improve the production line capacity, greatly reduce the labor load of workers, and improve product quality.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The first aspect of the present invention is to provide a method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe, comprising the following steps:

[0009] (1) providing a nozzle having a conical nozzle at one end, wherein the nozzle can move axially and reciprocally within the composite steel pipe and can rotate circumferentially;

[0010] (2) The composite steel pipe to be cleaned is placed horizontally, and a nozzle having a conical nozzle at the end is manually placed into the composite steel pipe to be cleaned;

[0011] (3) The linear velocity v and circumferential rotational speed ρ of the nozzle in the composite steel pipe are controlled as follows:

[0012] The linear velocity of the nozzle is

[0013] The circumferential rotation speed of the nozzle is

[0014] Among them, the parameters are defined as: length L of composite steel pipe, inner wall diameter D; number of nozzles N, flow rate of a single nozzle F, spray cone angle θ; spray coverage W of the inner wall surface of the steel pipe.

[0015] Preferably, in step (1), the nozzle is a corrosion-resistant pipe with a closed end, and a conical nozzle is installed on the peripheral body near the end, the spraying direction of the conical nozzle is perpendicular to the axial direction of the nozzle, and the spray cone angle θ is 90°.

[0016] Preferably, in step (1), the number of the conical nozzles is N, N≧2, and they are arranged at equal intervals in the circumferential direction.

[0017] Preferably, in step (3), the linear speed and rotational speed of the nozzle are both steplessly regulated by a speed regulator on the motor.

[0018] Preferably, in step (3), the spray coverage W on the inner wall surface of the steel pipe is 100-250 mL / m 2 .

[0019] Preferably, in step (1), the nozzle tip is provided with at least one conical nozzle, wherein:

[0020] One end of the spray pipe is closed, and the other end is connected to the pickling liquid storage tank through a connecting hose, and a delivery pump and a solenoid valve are installed on the connecting hose;

[0021] The conical nozzle is mounted on the outer peripheral body of the closed end of the nozzle, and the interior of the conical nozzle is communicated with the inner cavity of the nozzle. The pickling liquid in the nozzle is uniformly sprayed out in a cone shape under pressure.

[0022] Preferably, in step (1), the nozzle used is a square tube or a round tube, which is made of corrosion-resistant material.

[0023] Preferably, in step (1), the conical nozzles used are multiple and are arranged equidistantly along the outer periphery of the closed end of the nozzle, and their spraying directions are perpendicular to the axial direction of the nozzle.

[0024] The present invention adopts the above technical solution, which has the following technical effects compared with the prior art:

[0025] The method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe provided by the present invention can achieve the purpose of automatically controlling the spray pickling of the inner wall by installing a nozzle that can perform axial and axial movements simultaneously in the composite steel pipe, and using a nozzle installed on the head end of the nozzle to remove the oxide layer on the inner wall of the composite steel pipe, thereby effectively overcoming the technical defects of the existing cleaning methods, greatly improving the production line capacity, greatly reducing the labor load of workers, and improving the pickling quality of the composite steel pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a process flow of a method for controlling the pickling of an oxide layer on the inner wall of a composite steel pipe according to the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of the nozzle and the conical nozzle used in the method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe of the present invention;

[0028] The reference numerals in the drawings are: 1-composite steel pipe; 2-nozzle; 3-conical nozzle. DETAILED DESCRIPTION

[0029] The present invention is described in detail and specifically by specific examples below to provide a better understanding of the present invention, but the following examples do not limit the scope of the present invention.

[0030] In some embodiments, Figure 1 and Figure 2 As shown, a method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe is provided, which specifically comprises the following steps:

[0031] (1) A nozzle 2 having a conical nozzle 3 at one end is provided, and the nozzle 3 can move axially and reciprocally in the composite steel pipe 1 along with the nozzle 2, and can rotate circumferentially; one end of the nozzle 2 is closed, and the liquid inlet end of the other end is connected to the delivery pump and the acid storage tank through a connecting hose;

[0032] (2) The composite steel pipe 1 to be cleaned is placed horizontally, and a nozzle 2 having a conical nozzle 3 at the end thereof is manually placed into the composite steel pipe 1 to be cleaned;

[0033] (3) When in use, the acid liquid with pressure enters the nozzle 2 and is uniformly sprayed out through the nozzle 3. The nozzle can make uniform reciprocating motion in the axial direction and can rotate unidirectionally. The linear velocity υ and circumferential rotation speed ρ of the nozzle 2 in the composite steel pipe 1 are controlled as follows:

[0034] The linear velocity of the nozzle is

[0035] The circumferential rotation speed of the nozzle is

[0036] Among them, the parameters are defined as: length L of composite steel pipe, inner wall diameter D; number of nozzles N, flow rate of a single nozzle F, spray cone angle θ; spray coverage W of the inner wall surface of the steel pipe.

[0037] In step (1), the nozzle is a corrosion-resistant pipe with a closed end, and a conical nozzle is installed on the peripheral body near the end, the spray direction of the conical nozzle is perpendicular to the axial direction of the nozzle, and the spray cone angle θ is 90°. The number and flow rate of the nozzle 3 are designed according to the conventional diameter of the pickling steel pipe, which is installed at one end of the nozzle, and the spray direction is perpendicular to the axial direction of the nozzle.

[0038] In step (1), the number of the conical nozzles is at least one; preferably N, N≧2, arranged at equal intervals in the circumferential direction, so as to evenly spray the acid solution on the inner wall of the composite steel pipe 1 to clean the oxide layer on the inner wall. The number of nozzles can be changed according to the flow rate and spray coverage of a single nozzle.

[0039] In step (3), in actual production applications, the nozzle 2 can move along the axial direction at a constant speed and rotate at a constant speed. The linear speed and rotation speed of the nozzle 2 are both steplessly regulated by the motor through the speed regulator.

[0040] In step (3), in order to ensure sufficient pickling effect without causing the liquid to flow down to the bottom of the steel pipe and form effluent, the spray coverage W on the inner wall surface of the steel pipe is 100-250 mL / m 2 The surface area is between 100 and 150 mm. This data is determined by the steel pipe material and surface characteristics.

[0041] like Figure 2 As shown, a composite steel pipe inner wall oxide layer pickling device for the above control method is provided, the pickling device mainly comprises a nozzle 2 and at least one conical nozzle 3, which is used for cleaning the inner wall oxide layer of the composite steel pipe 1.

[0042] One end of the nozzle 2 is closed, and the other end is connected to an acid storage tank through a connecting hose, and a delivery pump and a solenoid valve are installed on the connecting hose. The conical nozzle 3 is installed on the outer peripheral body of the closed end of the nozzle 2, and its interior is connected to the inner cavity of the nozzle 2. The acid in the nozzle 2 is uniformly sprayed in a cone under pressure.

[0043] The composite steel pipe 1 to be cleaned is a metal composite pipe. In the surface treatment process of the composite steel pipe 1 , it is necessary to use the spray pipe 2 with the nozzle 3 to remove the oxide layer on the inner wall of the composite steel pipe 1 using acid solution.

[0044] The nozzle 2 is a round tube, a square tube, or a combination thereof. Preferably, in this embodiment, the nozzle 2 is a round tube, one end of which is flanged or welded closed. It is made of corrosion-resistant material, specifically acid-resistant plastic or stainless steel.

[0045] There are a plurality of conical nozzles 3 which are arranged at equal intervals along the outer periphery of the closed end of the nozzle 2 . The interior of the conical nozzle 3 is connected to the cavity of the nozzle 2 , and its spraying direction is perpendicular to the axial direction of the nozzle 2 .

[0046] When in use, the acid in the nozzle 2 is uniformly sprayed out from the conical nozzle 3 in a cone shape under pressure to remove the oxide layer on the inner wall of the composite steel pipe 1. The number of conical nozzles 3 can be changed according to the flow rate and spray coverage of a single nozzle.

[0047] It is worth noting that in order to realize the linear movement and circumferential rotation of the nozzle 2 in the above-mentioned composite steel pipe inner wall oxide layer pickling control method. As one of the implementation methods, when in use, the end of the nozzle 2 is installed on the rotating motor in a detachable connection manner, and the rotating motor adopts a reduction motor, which can accurately control the rotation speed of the nozzle 2. And the rotating motor is installed on the linear screw module, and the linear movement speed of the nozzle 2 is accurately controlled by the linear screw module. The rotating motor and the linear screw module adopt the existing known reduction motor and linear slide, which are both electrically connected to the speed regulator, and the rotating motor and the linear screw module are accurately controlled by the speed regulator.

[0048] The pickling control method can achieve the purpose of automatically controlling the spray pickling of the inner wall by installing a nozzle 2 capable of simultaneous axial and axial movement in the composite steel pipe 1 to be treated, and using a nozzle 3 installed on the head end of the nozzle 2 to remove the oxide layer on the inner wall of the composite steel pipe 1, thereby effectively overcoming the technical defects of the existing cleaning methods, greatly improving the production line capacity, greatly reducing the labor load of workers, and improving the pickling quality of the composite steel pipe.

[0049] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe, characterized in that: The steps include: (1) providing a nozzle having a conical nozzle at one end, wherein the nozzle can move axially and reciprocally within the composite steel pipe and can rotate circumferentially; (2) The composite steel pipe to be cleaned is placed horizontally, and a nozzle having a conical nozzle at the end is manually placed into the composite steel pipe to be cleaned; (3) The linear velocity v and circumferential rotational speed ρ of the nozzle in the composite steel pipe are controlled as follows: The linear velocity of the nozzle is The circumferential rotation speed of the nozzle is Among them, the parameters are defined as: length L of composite steel pipe, inner wall diameter D; number of nozzles N, flow rate of a single nozzle F, spray cone angle θ; spray coverage W of the inner wall surface of the steel pipe.

2. The method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe according to claim 1, characterized in that: In step (1), the nozzle is a corrosion-resistant pipe with a closed end, and a conical nozzle is installed on the peripheral body near the end. The spray direction of the conical nozzle is perpendicular to the axial direction of the nozzle, and the spray cone angle θ is 90°.

3. The method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe according to claim 1, characterized in that: In step (1), the number of the conical nozzles is N, N≧2, and they are arranged at equal intervals in the circumferential direction.

4. The method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe according to claim 1, characterized in that: In step (3), the linear speed and rotational speed of the nozzle are both steplessly regulated by the speed regulator of the motor.

5. The method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe according to claim 1, characterized in that: In step (3), the spray coverage W on the inner wall surface of the steel pipe is 100-250 mL / m 2 .

6. The method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe according to claim 1, characterized in that: In step (1), the nozzle (2) is provided with at least one conical nozzle (3) at the end thereof, wherein: One end of the spray pipe (2) is closed, and the other end is connected to the pickling liquid storage tank via a connecting hose, and a delivery pump and a solenoid valve are installed on the connecting hose; The conical nozzle (3) is mounted on the outer peripheral body of the closed end of the nozzle (2), and its interior is connected to the inner cavity of the nozzle (2). The pickling liquid in the nozzle (2) is sprayed out uniformly in a cone shape under pressure.

7. The method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe according to claim 1, characterized in that: In step (1), the nozzle (2) used is a square tube or a round tube, which is made of corrosion-resistant material.

8. The method for controlling the pickling of the oxide layer on the inner wall of a composite steel pipe according to claim 1, characterized in that: In step (1), the conical nozzles (3) used are multiple and are arranged at equal intervals along the outer periphery of the closed end of the nozzle (2), and their spraying direction is perpendicular to the axial direction of the nozzle (2).

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