Method for cleaning outer surface of long product

Abstract

The invention relates to the treatment of rolled metal products, i.e. The removal of process lubricants on such products, and can be used for cleaning cylindrical long products, such as pipes, wires and bars, after cold rolling or cold drawing and before the application of various types of coatings, and also for surface finishing of the products. A method for cleaning an outer surface of a long product wherein the method comprises the steps of: passing the product through an annular chamber having an outlet nozzle; supplying a scrubbing solution and a compressed gas into the annular chamber; forming a turbulent flow of the gas-liquid flow in the outlet nozzle and supplying a pulsating gas-liquid flow to the outer surface of the product to be cleaned wherein hydrodynamic cavitation is formed on the outer surface of the product to be cleaned; wherein the solution is supplied in the form of a continuous flow at a constant pressure and simultaneously a pulsating compressed gas is supplied at a constant frequency in the range of 1 Hz to 20 Hz, whereby the velocity of the gas-liquid jet is varied, thereby forming a pulsating gas-liquid flow and hydrodynamic cavitation on the outer surface of the product to be cleaned. The technical effect is that the cleaning quality of the surface of the product is improved and the processing capacity is improved due to the action of hydrodynamic cavitation and omission of washing operation.

Description

Technical Field

[0001] The present invention relates to the treatment of rolled metal products, i.e. the removal of process lubricants from such products, and can be used for cleaning long cylindrical products such as pipes, wire and bars after cold rolling or cold drawing and before the application of various types of coatings, and also for surface finishing of the products. Background Art

[0002] A method for removing contaminants known from the prior art consists of saturating the scrubbing liquid with gas to below its solubility limit under normal conditions, and performing the cleaning in a gas-liquid flow, wherein the gas is released from the liquid by heating the product to be cleaned (USSR Copyright Certificate No. 1030058, B08B3 / 04, published on July 23, 1983). In this method, the gas bubbles released from the liquid create turbulence in the boundary layer above the surface to be cleaned, thereby improving the cleaning quality.

[0003] The disadvantage of this method is that the product must be preheated, which is not always feasible and cost-effective for technical and process reasons. This reduces the quality of the clean surface and can lead to the formation of oxide films.

[0004] A method for cleaning contaminants from long cylindrical products is known in the prior art, wherein the products are passed through an annular chamber device having a nozzle, into which a rotating flow of a cleaning liquid is fed, and turbulence is generated in the nozzle having annular projections and recesses formed on the inner surface (USSR Copyright Certificate No. 1276686, C23G3 / 04, C25D19 / 00, published on December 15, 1986).

[0005] The design of this apparatus does not ensure sufficient flow turbulence within the annular chamber and, therefore, cannot fully disrupt and remove certain contaminants, such as difficult-to-remove process lubricants.

[0006] A method for cleaning long cylindrical products is also known in the prior art, and is implemented using an apparatus, wherein the product is passed through an annular chamber having an outlet nozzle, a rotating flow of a cleaning liquid is supplied to the annular chamber, compressed air is added, and turbulence is generated in the outlet nozzle by an annular groove on the inner surface of the nozzle (Russian Federation Patent No. 2355484, B08B3 / 02, B05B1 / 02, published on July 27, 2008).

[0007] A disadvantage of this method and apparatus is that the cleaning efficiency of difficult-to-remove process lubricants is low due to the large amount of gas supplied and the resulting need to separate excess gas, and this makes the cleaning process more difficult.

[0008] The closest solution accepted as a prototype is a method for cleaning the outer surface of cylindrical products. The product is passed through an annular chamber with an outlet nozzle. A rotating flow of an aqueous cleaning solution and compressed air are fed into the annular chamber. By varying the pressure of the gas-liquid flow from 20 atmospheres to 1 atmosphere to create a pulsating gas-liquid flow, a turbulent gas-liquid flow is generated in the outlet nozzle. This flow is fed countercurrently to the product. Furthermore, a cleaning substance is added to the aqueous solution in an amount not exceeding 1.0%, and compressed air is fed in an amount not exceeding 10% of the volume of the cleaning aqueous solution. After being cleaned with the aqueous cleaning solution, the product is rinsed with water and dried with compressed air in the annular chamber with the outlet nozzle. Each medium is fed from the nozzle countercurrently to the product (Patent No. 2668033, B08B 3 / 02, B08B 9 / 023, B08B 3 / 08, published on September 25, 2018).

[0009] The disadvantages of this method are the technical complexity of implementing the process of changing the pressure of the gas-liquid stream from 20 atmospheres to 1 atmosphere, low capacity, low cleaning efficiency for difficult-to-remove contaminants, poor cleaning quality and the need to use scrubbing chemicals. Summary of the Invention

[0010] The technical task solved by the present invention is to create an effective method for removing process lubricants from the outer surface of long metal products after rolling and drawing and before heat treatment, coating and finishing operations.

[0011] The technical effect is that the cleaning quality of the product surface is improved and the processing capacity is increased due to the effect of hydrodynamic cavitation and the washing operation is omitted.

[0012] The technical effect is achieved by a method for cleaning the outer surface of a long product, the method comprising the following steps:

[0013] passing the product through an annular chamber having an outlet nozzle;

[0014] supplying a scrubbing solution and compressed gas into the annular chamber;

[0015] creating a turbulent gas-liquid flow in the outlet nozzle and supplying the pulsating gas-liquid flow to the outer surface of the product to be cleaned, wherein hydrodynamic cavitation is formed on the outer surface of the product to be cleaned;

[0016] In this process, the solution is supplied in the form of a continuous flow at a constant pressure and a pulsating compressed gas is supplied at a constant frequency in the range of 1 Hz to 20 Hz, thereby changing the speed of the gas-liquid jet, thereby forming a pulsating gas-liquid flow and hydrodynamic cavitation on the outer surface of the product to be cleaned.

[0017] Furthermore, the solution was supplied in a continuous flow at a constant pressure greater than 10 atmospheres.

[0018] Furthermore, the compressed gas is supplied at a constant pressure that exceeds the pressure of the solution by at least 1 atmosphere.

[0019] Furthermore, water was used as the solution, and air was used as the compressed gas.

[0020] Furthermore, the solution was supplied in a continuous flow at 30°C to 40°C. DETAILED DESCRIPTION

[0021] The claimed method for cleaning the outer surface of long products such as pipes, wires, rods and other long products comprises the following steps:

[0022] Pass the product (such as a pipe) through an annular chamber with an outlet nozzle,

[0023] The washing solution and compressed gas are supplied into the annular chamber.

[0024] A turbulent gas-liquid flow is formed in the outlet nozzle and the pulsating gas-liquid flow is supplied to the outer surface of the product to be cleaned, wherein hydrodynamic cavitation is formed on the outer surface of the product to be cleaned,

[0025] In this process, the solution is supplied in the form of a continuous flow at a constant pressure and a pulsating compressed gas is supplied at a constant frequency in the range of 1 Hz to 20 Hz, thereby changing the speed of the gas-liquid jet, thereby forming a pulsating gas-liquid flow and hydrodynamic cavitation on the outer surface of the product to be cleaned.

[0026] The solution may be supplied as a continuous stream at a constant pressure greater than 10 atmospheres, and the compressed gas may be supplied at a constant pressure at least 1 atmosphere above the pressure of the solution.

[0027] Water was used as the solution, and air was used as the compressed gas.

[0028] The motion of the gas-liquid flow on the outer surface of the cylindrical long product is turbulent in nature. The pulsating supply of compressed gas at the outlet of the annular chamber's outlet nozzle causes rapid changes in the velocity and pressure of the liquid flow on the outer surface of the long product. This causes the occurrence of hydrodynamic cavitation, which removes residual contaminants and process lubricants from the product surface.

[0029] In the area where the pulsating supply of compressed gas increases the flow velocity of the liquid and causes a sharp drop in pressure, the volume of the gas bubbles changes, causing them to burst and destroy the tenacious contamination layer on the outer surface of the cylindrical long product. Compressed gas is primarily supplied at a pressure at least 1 atmosphere higher than the pressure of the solution to prevent the solution from flowing into the compressed gas supply system.

[0030] The use of water as a solution eliminates the need for washing the product, thereby increasing processing capacity.

[0031] The method for cleaning the outer surface of long metal products (such as pipes, wire, and rods) prior to heat treatment, coating, finishing, and the like can be implemented in an apparatus comprising, for example, an annular chamber with an outlet nozzle connected to two branches of a distributor that continuously supplies a solution to the surface of the product to be cleaned while simultaneously pulsating a compressed gas. The solution is supplied at a constant pressure (preferably greater than 10 atmospheres) at a temperature of 30 to 40 degrees Celsius. The pulsating supply of compressed gas is carried out at a constant frequency in the range of 1 Hz to 20 Hz (at frequencies below 1 Hz and above 20 Hz, cavitation is virtually absent) and at a pressure that exceeds the pressure of the solution by at least 1 atmosphere.

[0032] The quality control of the cleaning is carried out by evaluating the degree of contamination of a white cotton cloth wiped on the inner surface of a pipe longer than 1 m and weighing it before and after wiping.

[0033] The proposed cleaning method leaves the outer surface of the product free of residual contaminants and improves handling capabilities.

[0034] The specific implementation is as follows.

[0035] The proposed method was used to clean (remove Castrol TDN86, a process lubricant) the outer surface of cold-rolled stainless steel pipes of 12X18H10T alloy with a diameter of 16 mm, a thickness of 1 mm, a length ranging from 4 m to 24 m, and an average initial contamination of 6080 mg / m 2 The pipe was cleaned in water using an experimental pulsating jet cavitation cleaning device.

[0036] The surface of the pipe to be cleaned is continuously supplied with a solution and simultaneously pulsed with compressed gas. The solution is supplied at a constant pressure of 12 atmospheres at a temperature of 30 to 40 degrees Celsius. The compressed gas is compressed air at a frequency of 15 Hz and a pressure of 17 atmospheres.

[0037] Next, the cleanliness of the outer surface of the pipe is quality controlled.

[0038] The test results are shown in the following table.

[0039] Table. Capacity of the device to clean the external surface of pipes of different lengths.

[0040]

[0041] Conducted pilot tests have shown that the duration of high-quality cleaning (no residual contamination) of pipelines of different lengths is identical and lies in the range of 1 to 3 minutes, and that the longer the pipeline, the higher the capacity of the cleaning process.

[0042] Cleaning processes of less than 1 minute do not ensure the required quality of the outer surface of the pipe.

[0043] Similar cleaning results are obtained when cleaning the exterior surfaces of pipes made of titanium, zirconium, molybdenum and other types of alloys.

[0044] Compared to known methods for cleaning external surfaces (specifically for removing lubricants), the proposed cleaning method reduces the duration by a factor of 3 to 3.5. Based on the data presented in the table, the ability of industrial plants to clean long pipelines (10 to 40 m) will also be increased by a factor of 3 to 3.5.

[0045] Therefore, compared with known methods, the proposed method for cleaning the outer surface of long products is environmentally safe, efficient and can reduce energy consumption, reduce resource costs, significantly reduce the time spent on cleaning the product surface, and improve the processing capacity and cleaning quality by obtaining a surface free of residual contaminants, because the pulsating supply of compressed air will cause the velocity and pressure of the gas-liquid flow on the outer surface of the cylindrical product to change sharply, so as to induce the occurrence of hydrodynamic cavitation, thereby completely removing the process lubricant on the surface.

Claims

1. A method for cleaning the outer surface of a long product, characterized in that The method comprises the following steps: passing the product through an annular chamber having an outlet nozzle; supplying a washing solution and compressed gas into the annular chamber; forming a turbulent gas-liquid flow in the outlet nozzle and supplying the pulsating gas-liquid flow to the outer surface of the product to be cleaned, wherein hydrodynamic cavitation is formed on the outer surface of the product to be cleaned; The solution is supplied in the form of a continuous flow at a constant pressure and a pulsating compressed gas is supplied at a constant frequency in the range of 1 Hz to 20 Hz, thereby changing the speed of the gas-liquid jet, thereby forming a pulsating gas-liquid flow and hydrodynamic cavitation on the outer surface of the product to be cleaned.

2. The method for cleaning the outer surface of a long product according to claim 1, characterized in that The solution was supplied as a continuous flow at a constant pressure greater than 10 atmospheres.

3. The method for cleaning the outer surface of a long product according to claim 1, characterized in that The compressed gas is supplied at a constant pressure that exceeds the pressure of the solution by at least 1 atmosphere.

4. The method for cleaning the outer surface of a long product according to claim 1, characterized in that Water was used as the solution, and air was used as the compressed gas.

5. The method for cleaning the outer surface of a long product according to claim 1, characterized in that The solution was fed in a continuous flow at 30 to 40°C.

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