CS540185A2 - Method of workpieces pickling for tubes production and equipment for this method realization - Google Patents

Description

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BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a method and apparatus for pickling cavities, such as perforated tubular billets or tubes.

It is known that the surfaces of metal, especially steel objects, are made by contacting the surface with acids, acid mixtures, alkali, or a mixture of salts prior to the formation of the sea.

For example, in the processing of iron workpieces, in particular steel, such as perforated tubular billets or tubes and in particular perforated tubular billets for seamless tubes in devices such as extrusion stands, step rolling mills, tube rolling mills, pilgrim rolling mills, stamping presses, etc. insertion of the rods inside the perforated tubular billets or tubecorons in the rolling temperature range, i. at 1000 to 1300 ° C. Due to the nature of the rolling mills' workflow, it has not yet been possible to achieve a complete, complete pickling process in rational ways, since only as short a time period as 1 second was sometimes available for the mordant application. in

It has already been proposed to remove scale from perforated tubular billets in which the mordant is introduced by compressed air through the circulation path at one end into the billet heated to the rolling temperature, and at the other end is discharged by removing the mixture residues.

This method has the disadvantage of a large consumption of amorphous gas. From an economical point of view, gas is generally used as a gas, which, in particular in said larger amounts, exerts a considerable oxidative effect on the billets and also strongly cools them.

Also, the extraction of mixture residues and purification from the gas and yolium is very problematic. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus which allows a continuous and, if possible, complete, complete, low-cost installation with appropriate quantities of scouring agent to be carried out in the rolling mill process.

The essence of the process according to the invention is that the melt, suitably in dry form as a powder, is filled into a container with an average size of 50 to 1000 microns or as a granulate with an average grain size of 0.5 to 4 mm. It is then transferred to a metering device, typically by means of self-weighting, if necessary with the aid of, for example, vibration, by means of a mixing pad or by means of air blowing, so as to prevent the powder from spinning. Optionally, the pressure vessel may be formed as a silo, and the material is then discharged by pressure. Suitable metering devices are known as dispensing devices, such as dispensing scales, dispensing worms, dispensing spirals and vibratory feeders. The dosage can be performed volumetrically or gravitationally; the dosage is volumetric, for example a screw dispenser may be used. The pickling device proceeds to the pressurized container. This pressure vessel is filled with gas under pressure. Suitable gas may be air, nitrogen, carbon dioxide, noble gas, or a mixture of these gases. In the method of the invention, 5 to 100 g of mordant per m 2 of interior surface or interior wall of the workpiece are used. Suitably 10 to 60 g, preferably 25 to 50 g, of mordant per m of inner wall are used.

The amount of gas is 50 to 750 liters per kg of mordant. According to a preferred embodiment, 100 to 500 liters, preferably 100 to 250 liters of gas per kf of stain are used.

The pressure in the pressure vessel should be 2 to 20 bar, preferably 2 to 10 bar.

If an appropriate filling of the pressure vessel is achieved, a stain can be processed and applied within the working cycle of the rolling mill. For this purpose, there is a conveying line which leads to the discharge device. For example, the discharge device may be provided with a simple tubular opening, an outlet cone, or a spiral or diffuser, and various types of nozzles may also be used.

In order to uniformly disperse and deposit the scavenger in the cavity of the workpiece, it is necessary to achieve a circulating, amino, turbulent or pulsating flow of the gas mixture and the mordant, with circulation or turbulent flow being desired.

By circulating flow is meant that the process-mixture is the hollow space of the workpiece to form a helical motion, hminmin flow means that the mixture passes through the workpiece aperture through a substantially uniform motion while vortexing occurs during turbulent flow. flowing media. Pulse Flow describes the way in which a mixture is guided through a hole in a workpiece at multiple pressure surges.

The discharge device can be arranged centrally but also eccentrically to the hole in the workpiece in the region of the workpiece end. However, it is also possible to drive the discharge device inside the product or, during the discharge of the mixture, to guide the discharge device through the entire hole in the workpiece. As a rule, during the use of the dressing agent, the rolling temperature is about 1000 to 1300 ° C, and the temperature changes can still be formed between the pickling step and the rolling step.

The process according to the invention is carried out by means of a device, which is exemplified and schematically shown in Figure 1.

According to the invention, the device comprises a pickling container 1 on which a volumetric or gravimetric dosing device 2 is connected, which is discharged into the pressure vessel 3,. * ·

The pressure vessel 3 is provided with a supply of pressurized air 4 and an outlet 5 for the gas mixture and the mordant. The outlet 5 is controlled by the opening valve 6, and after opening the valve, the melt and the mordant flow through the conveying line 2 to the discharge device 8 '

At the same time, the discharge device 8 functions as a distributing device and at the same time ensures a uniform deposition.

Another essential feature of the pressure vessel is the formation of a drain 5. · This must ensure that during the working process the material is applied completely and without re-weighing. a technical measure to achieve this goal is to create a pressure vessel with walls, steeply sloping towards the outlet and / or forming a cone in the outlet area.

Another feature of the arrangement is the possibility of preheating the gas and / or the mordant, either in front of or inside the pressure vessel or in the transport wagon. With relatively small amounts of gas pickling agent, preheating can be easily accomplished. It is also possible, by adapting the dispensing device and the dispensing device, to work with the mordant in the same manner in the liquid form as with the solution, suspension or melt.

Known elements can be used as valves and control elements for the metering device 9, 10 for supplying compressed air 11 and for the outlet 5. The regulation can be carried out, for example, mechanically, hydraulically, pneumatically or electromagnetically, the control corresponding to the current working stage of the rolling mill being achieved in a manner known per se, for example by manual regulation, mechanically or electronically »

1 further shows a section, for example a perforated tubular billet or tube 12, and a hollow space, shown as an internal workpiece blank 13.

The method according to the invention achieves a uniform dispersion of the sealant in the interior of the workpiece without any re-scaling, and thus a chemical conversion, respectively. modification okujíe

The use of staining is ideally not only to produce a uniform and well-adhering thin surface layer, but that the products formed on the inner surface of the workpieces have abrasive or even lubricating properties.

By using smaller amounts of gas than in the known descaling processes, the use of air as the pressurized gas causes relatively smaller amounts of oxygen to contact the workpiece heated to the rolling temperature, which considerably reduces the formation of new oxidation products. The use of inert gases such as nitrogen or noble gases is then economically viable at low gas levels.

Compared to the known descaling methods, relatively smaller amounts of mordant are required per unit area according to the invention. Due to the small amounts of gas used and the mordant, the process of the present invention makes it unnecessary to aspirate the gas mordant mixture previously used. The backward blend of the workpiece opening which is readily occurring in the manner of the present invention does not occur here at a disturbing rate. The gas and / or non-burner are preheated in the process of the invention so that these problems can be completely neglected.

Furthermore, the flow used causes the most homogeneous dispersion of the mordant on the inner surface of the workpiece, so that no excess staining is required which would otherwise be returned or would be lost.

Claims (12)

1. A method of pickling workpieces for the production of tubes heated to a rolling temperature, characterized in that the pickling agent is metered volumetrically or gravimetrically2 into a pressure vessel in an amount of 5 to 100 g of mordant per 1 m of the inside of the workpiece, the pressure vessel being fed to the 1 a kilogram of stain is 50 to 70 liters of gas, and the gas and stain in the form of a homogeneous mixture are conveyed through a conveying line to the discharge device, received by a circulation, turbulent, laminar or pulsed flow to the workpiece heated to the rolling temperature and applied to the workpiece walls, , 2. Process according to claim 1, characterized in that the dressing is volumetric 3. The process according to claim 1, wherein 10 to 60 g, preferably 25 to 50 g of mordant are present per m of the surface of the inner walls of the workpiece and 100 to 500 liters of gaseous is preferred per kilogram of mordant, preferably 100 to 250 liters. 4. Method according to claim 1, characterized in that the discharge device is machined during the discharge of the mordant into the cavity by the hollow space of the workpiece. 5. Method according to claim 1, characterized in that the pickling device is guided by a discharge device located in the region of the concave body into the cavity of the workpiece and applied to the inner walls of the workpiece. 6. A process according to any one of claims 1 to 6, wherein the gas is air, nitrogen, carbon dioxide, any of the noble gases or a mixture of these gases. 7. A process according to any one of claims 1 to 6 wherein the mordant is used in dry form as a powder having an average size of 50 to 1000 microns or as a granulate with an average grain size of 0.5 to 4 mm < 8 > 7, characterized in that the pressure vessel is supplied with pressurized air to a pressure of 2 to 20 bar, preferably 2 to 10 bar® - 8 - PATENT CLAIMS 9. A method according to any one of claims 1 to 8, characterized in that a staining agent for the perforated tubular billets is used and applied to the inner walls of the hollow space of the billets. a mordant attached to a volumetric or gravimetric dispenser which is emptied into a pressure vessel and pressurized 10 - the vessel is provided with a pressurized air inlet and a gas outlet and mordant outlet, the outlet being controlled by an opening valve and the apparatus further comprising a conveying line and a discharge device for the gas / mordant mixture at the end thereof. 11. Apparatus according to claim 10, wherein a volumetric metering device is used as the metering device. 12. Apparatus according to claim 10 or 11, characterized in that a screw dispenser is used as the dispensing device. - ÚsUv tes & akV »J? Asvcje a řsiísrrační, P R A K? Sov3v''c! I ras / vi r) U 3 S b P R A Λ Λ 1 (M) t '> r ~ O 1/1