RU2373304C2 - Method of jet etching of pipes inner surface and device for its implementation - Google Patents

Abstract

FIELD: metallurgy industry.

SUBSTANCE: invention refers to chemical treatment of metals and may be used for jet etching of pipes inner surface, for example pipes for heat-producing elements made of zirconium alloys. Method includes loading and fixation of pipes in certain position, treatment of their inner surface by series supply with direction change of etch solution, water and compressed air, pipes unloading. Etch solution is provided by compressed air, each pipe is treated at three positions one by one, at first position etch solution is provided in one direction, then clean compressed air is provided in the same direction, at second position etch solution is provided in opposite direction, then clean compressed air is provided in the same direction, at third position water is provided, then clean compressed air, pipes treatment at each position is performed with jet break-up at outlet. Device contains frame, mechanism of delivery and unloading of pipes, mechanisms of pipes fixation, system for treating agents running through pipes consisting of pipelines, containers and valves. Frame contains three operation positions, mechanisms for pipes delivery to operation positions, on each position there are hard-mounted gaskets from the side of treating agents supply and moving-mounted gaskets along frame - devices for receiving from pipes with jet break-up of treating agents. System for treating agents running through pipes includes additionally intermediate containers connected to pipelines, through which etch solution and compressed air are run, and connected to treated pipes using gaskets.

EFFECT: development of device for effective jet etching of pipes inner surface.

7 cl, 3 dwg, 1 tbl, 1 ex

Description

The invention relates to the chemical treatment of metals and can be used for jet etching of the inner surface of pipes, for example, pipes for fuel elements made of zirconium alloys.

It is known that jet-circulation treatment is used to intensify the processes of chemical treatment of pipes, as well as to ensure high-quality processing of the inner surface of the channels.

Closest to the proposed invention relating to the method of jet etching of the inner surface of the pipe is the method according to patent DE 3825 533 A, C23F 1/16 (publ. 09.02.89).

The method includes loading the pipes, fixing several pipes in a certain position, installing mouthpieces on the open ends of the pipes to prevent atmospheric air from entering the pipes, connecting the internal space of the pipes to a system that pumps through the pipes a substance that processes their internal surfaces, and treating the internal surfaces of each from pipes it is carried out at one position by feeding sequentially and with a change in the direction of the acid for pickling and water for washing, and then feeding th compressed steam as a means for cleaning the inner surface of the pipes and compressed air as a desiccant.

However, the treatment of the inner surface of the pipes with various substances at the same working position leads to their mixing in the pipes to be treated and the drain pipe. The pipes to be treated are under overpressure, which consists of linear pressure losses in the pipe being processed, local and linear losses of the process pipe drainage system, which leads to a loss in the etching solution flow rate in the pipes being processed, and to a decrease in the uniformity of metal removal in the pipe depending on its length .

The same patent describes a device by which an etching method is carried out, comprising a bed, clamps for fixing several pipes in a certain position, mouthpieces mounted to move between the initial and working positions of the pipes and in the working position isolating the inner space of the pipe from the external air environment , a control device for selectively connecting flows of material for pumping through the inner surfaces of the pipes.

This device, as well as the method, does not provide a high and uniform speed of the processing substance through the pipes, which does not allow the etching of pipes efficiently and with high quality. The disadvantages of the device include the need to use pumps to supply highly aggressive pickling solutions.

The task of the invention is to increase the efficiency, accuracy and quality of processing due to the uniformity of removal of metal along the length of the pipe.

To obtain such a technical result in the proposed method of jet etching of the inner surface of the pipes, including loading and fixing the pipes in a certain position, processing their inner surface by sequential feeding with changing the direction of the etching solution, water and compressed air and unloading the pipes, feeding the etching solution is carried out with compressed air, each pipe is alternately treated in three positions, while the first position serves etching solution in one direction, then the cleaned compressed air in the same direction, at the second position, the etching solution is fed in the opposite direction, then purified compressed air in the same direction, water is supplied at the third position, then purified compressed air, the pipes are treated at each position with a stream breaking at the outlet.

The distinguishing features of the invention, namely the processing of pipes in three positions, with the etching solution and compressed air in the first direction in the first position, the etching solution and the compressed air in the second position in the opposite direction, with the supply of water in the third position, together allows that the etching solution and water are supplied to the inner surfaces of the pipes by compressed air and the pipes are treated at each position with a rupture of the jet at the outlet, to carry out the etching process with a high uniform minutes in length pipes speed of the etching solution, without linear and local head loss in the return line, since processing is performed in the through mode. This provides an effective and uniform removal of metal along the length of the pipes, thereby achieving high quality and precision machining.

An additional technical result is the ability to use the pickling solution repeatedly after regeneration, since the technological solutions in the processed pipes and drain pipelines do not mix due to processing at different positions.

For etching pipes made of zirconium alloys, it is preferable to use an etching solution of the following composition:

the content of nitric acid, g / l from 450 to 550 free fluorine content, g / l from 5 to 12 water rest

Most preferred is the free fluorine content in the etching solution of 5 ÷ 7.5 g / l.

To achieve the technical result, a device is proposed that includes a bed, a pipe feeding and unloading mechanism, pipe fixing mechanisms, a system for pumping substances through the pipes that process the inner surface of the pipes, consisting of pipelines, containers and taps, and the bed contains three working positions for pipe processing, mechanisms for feeding pipes to working positions, at each position seals are fixedly mounted on the supply side of substances that process, and movably along beds - means for receiving from a pipe with a rupture of a jet of substances that process, and a system for pumping through a pipe substances that process, additionally includes intermediate containers associated with pipelines supplying the pickling solution and compressed air, and connected through seals to the pipes to be processed.

The proposed flow-through device allows you to process up to 120 pipes per hour.

The bed can be made inclined in the direction of unloading pipes.

The mechanisms for fixing the pipes are preferably made in the form of a carriage mounted at each position with the possibility of moving along the bed of the carriage with a tong for feeding the pipe into the sealant and a mechanism for supplying means for receiving processing substances at the other end of the pipe.

The means for receiving with a rupture of the jet of substances that process, can be made in the form of a receiving head and contains a sealed housing equipped with a sleeve, which in the working position covers the end of the pipe, a ventilation pipe and a manifold.

The invention is illustrated by drawings, where figure 1 shows a device for implementing the method of jet etching of the inner surface of the pipes, figure 2 is a schematic diagram of the pneumohydraulic circuit, figure 3 - receiving head.

The proposed method is carried out in the following sequence. A batch of pipes is loaded onto the drive, the first pipe is fed to the first working position, sealed from the side of the pickling solution supply and fixed. On the opposite end of the pipe put on the receiving head. The etching solution is supplied using purified compressed air, the etching solution exits the pipe freely with a jet break. Then the remains of the etching solution are purged with purified compressed air, the pipe is released and transferred to the second working position, where the same actions are carried out, but from the opposite end of the pipe. At the third working position, they are washed with water and purged with purified compressed air, and the treated pipe is unloaded. Processing of the second and subsequent pipes begin after the release of the first working position.

The implementation of the method allows for a minimum etching solution pressure (0.2 MPa) to carry out the etching process with high linear velocities up to 4.5 m / s with the transition of the etching process to polishing mode. This reduces the surface roughness and increases the accuracy of processing, and the resulting slag is removed by the flow of pickling solution from the inner space of the pipe into the drain manifold.

The device for processing by jet etching of the inner surface of the pipe contains the following elements (see Fig.1-3):

- bed 1;

- drive 2;

- first job position 3;

- second working position 4;

- third job position 5;

- a mechanism for supplying pipes to the first working position 6;

- gasket with pickling head 7;

- a carriage with a tong 8 for feeding the pipe into the seal 7 of the pickling head;

- receiving head 9 (figure 1, 2) with a sleeve 10, a manifold 11 and a ventilation pipe 12 (figure 3);

- the feed mechanism of the receiving head 13 (figure 1);

- the mechanism 14 for supplying the pipe to the second working position 4 (figure 2);

- a seal with a flushing head 15 (figure 2);

- a system for pumping substances carrying out processing through pipes includes:

- pipelines 16;

- intermediate tank 17;

- intermediate tank 18;

- a tap for supplying compressed air 19 to the intermediate tank 17;

- pickling solution feed valve 20;

- air supply valve purge 21;

- installation for cleaning compressed air 22;

- etching solution regeneration unit 23.

The device operates as follows. The processed pipe is fed from the drive 2 to the first working position 3 of the bed 1 by the mechanism 6, moved to the seal of the etching head 7 with a carriage with a grab 8. At the opposite end of the pipe, the receiving head 9 is fed with a sleeve 9 with a sleeve 10, a manifold 11, a ventilation pipe 12. Turn on the crane 19 supplying compressed air to the intermediate container 17 and the etching solution supply valve 20, after etching, close the taps 19 and 20, open the valve 21 for supplying compressed air to the purge, at the end of the purge, close the valve 21, take the receiving g the casing 9 by the mechanism 13 to the initial position, the pipe is released from the seal of the etching head 7 by the carriage with a tong 8, the pipe is transferred by the mechanism 14 to the second working position 4. At the second working position, the same operations are performed as at the first position, but the etching is carried out in the opposite direction from the tank 18. At the third working position 5, the same operations are carried out, but water is used for washing and a washing head 15. The second and subsequent pipe are automatically loaded after the first working position is released. All actuators of mechanisms and cranes based on pneumatic cylinders with sensors for monitoring the end positions of actuators and pipe positions at all positions. The purified compressed air is prepared at the compressed air purification unit 22. After processing the batch of pipes, the etching solution is regenerated at the regeneration unit 23, which allows it to be reused. The device operates in automatic mode.

The pickling head, the washing head and the receiving head are moved relative to the guide frames when changing to a different pipe size along the length. When switching to a different diameter diameter, the seals in the pickling, washing heads and sleeve 10 (see Fig. 3) in the receiving heads are changed.

Example

Experimental verification of the claimed method was carried out on the device for etching the inner surface of the pipes with a diameter of 9.1-9.13 mm, length from 2.5 to 4.5 m, etching solutions:

the content of nitric acid, g / l from 450 to 550 free fluorine content, g / l from 5 to 12 water rest

Processed 15 lots of pipes totaling 3059 pieces. The results of the experiments were evaluated by the presence of internal defects in the pipe, deviation from dimensions along the wall thickness, surface roughness of the initial and final, which are presented in the table.

Analysis of the results shown in the table shows that the proposed method and device provide high accuracy and quality of metal removal along the pipe length, diameter, with a surface roughness of Ra 0.2-0.3 microns.

Saving etching solution was 100%.

Claims (7)

1. The method of blasting the inner surface of the pipes, including loading and fixing the pipes in a certain position, treating their inner surface with a sequential feed with a change in the direction of the etching solution, water and compressed air, unloading the pipes, characterized in that the etching solution is supplied with compressed air, each the pipe is alternately treated at three positions, while at the first position the etching solution is fed in one direction, then the purified compressed air in the same direction, at the second zitsii supplied pickling solution in the opposite direction, then the purified compressed air in the same direction, at the third position of supplying water, then purified compressed air, process tubes at each position leads to rupture of the jet at the outlet. 2. The method according to claim 1, characterized in that for the jet treatment of pipes made of zirconium alloys using etching solution composition, g / l:
Nitric acid from 450 to 550 fluoride free from 5 to 12 water rest. 3. The method according to claim 2, characterized in that the content of free fluorine in the etching solution is 5-7.5 g / L. 4. A device for blasting the inner surface of pipes, including a bed, a mechanism for feeding and unloading pipes, pipe fixing mechanisms, a system for pumping through pipes substances that process the inner surface of pipes, consisting of pipelines, containers and taps, characterized in that the bed contains three working positions for processing pipes, mechanisms for feeding pipes to working positions, at each position seals are fixedly installed on the supply side of substances for processing, and movably along the bed - medium wa for receiving from tubes with a gap jet substances for the treatment and the system for pumping substances through tubes for processing further includes intermediate tank connected with pipelines, inlet pickling solution and compressed air, and are connected through seals to be handled tubes. 5. The device according to claim 3, characterized in that the bed is made inclined towards the discharge of pipes. 6. The device according to claim 3, characterized in that the mechanisms for fixing the pipes are made in the form of a carriage mounted on each position with the possibility of movement along the bed of the carriage with a span for supplying the pipe to the sealant and a mechanism for supplying reception means to the other end of the pipe with a break substances for processing. 7. The device according to claim 3, characterized in that the means for receiving with a break in the jet of substances for processing is made in the form of a receiving head and comprises a sealed housing equipped with a sleeve, which in the working position covers the end of the pipe, a ventilation pipe and a manifold.

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