RU2271890C2 - Method for preparing surface of elongated cylindrical blank to drawing and apparatus for performing the same - Google Patents

Abstract

FIELD: drawing and sizing processes and equipment, namely process and apparatus for preparing surface of elongated cylindrical blank to drawing, particularly to application of under-lubricant and then lubricant coating layers.

SUBSTANCE: method comprises step of applying under-lubricant coating in the form of rosin. Such coating is applied on surface of blank at rubbing it with soft porous tampons impregnated with rosin solution, then drying it in manufacturing line and preliminarily mechanically removing scale from blank for further drawing it. Apparatus for applying under-lubricant coating includes sealed chamber for passing blank through it in lower part of which bath tank filled with liquid solution of rosin is arranged; successively placed in said chamber double-roller guides inclined to horizon by different angle. Rollers of said guides are covered with soft and porous material; lower rollers are partially immersed into said solution. Capillary tubes may be used for feeding solution.

EFFECT: possibility for increasing thickness and integrity degree of under-lubricant layer of rosin, simplified design of apparatus for performing the method.

11 cl, 1 dwg, 1 ex

Description

The group of inventions relates to the field of drawing and calibration production, in particular to the technology of preparing the surface of the workpiece for drawing and devices that implement such a technology.

A known method of preparing the surface of the workpiece for drawing, in which the pre-cleaned from scale surface of the workpiece is coated with a lubricant in the form of mineral or vegetable oil or an aqueous emulsion of one of these oils, and the lubricant is pre-foamed using sparging and after exposure to air the blank with coating heated for a regulated time to a regulated temperature for the polymerization of the lubricant, and then on the lubricant coating applied powder lubricant, for example sodium soap powder (see., e.g., SU AS №1103922, cl. B 21 C 9/00, 1984) / 1 /. A device for implementing the method comprises a bath with a lubricating fluid, with input and output wiring in front of and behind the bath, and means for drawing the workpiece through the bath, as well as a number of additional devices - an oven, a bubbler / ibid /.

The polymerization of the lubricant is intended to use a higher adhesive ability, which, as previously established, is inherent in materials containing substances of high molecular weight (see M.T.Cocroft. Lubrication in metal forming processes, M .: Metallurgy, 1979, p. 101) / 2 /. Particularly effective is a lubricant coating of such a material in combination with a powder lubricant applied to it.

The specified known method, although it provides high quality retention of lubricant on the surface of the workpiece, has a low processability. A significant number of operations (introducing a blowing agent into the oil or emulsion, foaming the liquid, additional polymerization of the lubricant by heating, etc.) makes the process unproductive and time-consuming. Accordingly, the device for implementing the method is quite difficult, additionally includes a furnace and a bubbler. The coating process itself by dipping the workpiece into the bath is inefficient and requires a large excess amount of lubricant.

A known method of preparing the surface of the workpiece for drawing, including applying a lubricant coating in the form of a thermoplastic substance of high molecular weight and subsequent application of a powdered lubricant (see, for example, SU a.s. No. 1775201, class B 21 C 9/00, 1992) / 3 /. A device for implementing the method comprises a bath with a polymer, means for heating the polymer material and means for pulling the workpiece / ibid /.

In this method, a finished polymer of high molecular weight is used as the working material, however, the process of applying it to the surface of the workpiece is still rather laborious, because It provides for the preliminary transfer of the polymer material into a liquid viscous state by heating, applying it in this state to the surface of the workpiece and, finally, cooling the workpiece with a lubricated coating to a temperature at which the polymer goes back into an elastic pasty state, but its vitrification has not yet occurred.

The condition for using a polymer of a sufficiently large molecular weight is caused by the requirement to have some difference in the melting and glass transition temperatures, which is satisfied starting from a certain critical value of the molecular weight, specific for each type of polymer.

Given the need to maintain the temperature of the workpiece before applying the lubricant coating above the glass transition temperature, as well as the difficulty of maintaining the integrity and purity of the lubricant coating during storage and reheating, the described method is intended primarily for use in a drawing stream.

And although in the end the described known method allows to stabilize the drawing process and improve the surface quality of the workpiece, another disadvantage is the high polymer consumption due to unreasonably excessive (more than 20 microns) coating thickness.

Finally, at very high reductions or when drawing high-strength metals, even when using a polymer lubricant coating, the effectiveness of the method may be insufficient due to the insufficient adhesion forces of the polymer coating to the metal, due to the chemical inertness of most polymers, including polyethylene and polystyrene. In the above examples, the implementation of the compression method does not exceed 15%.

In addition, the excess polymer coating the product is heated by the heat of drawing and is driven away from the zone of formation of the lubricant wedge in the die into the zone of application of the lubricant powder, where a cooling elastic mass will soon form from a mixture of polymer and lubricant powder, which prevents the lubricant from entering the fiber, which also reduces the efficiency of the drawing process.

As for the device that implements this method, it, although it allows you to directly heat the liquid coating applied to the surface of the workpiece before drawing, however, the process of applying a lubricant coating in this device is carried out traditionally, i.e. by immersing the workpiece in a large volume (bath) of liquid material, which again determines the large consumption of this material with a small coefficient of its real use. The need to use means of heating the polymeric material further complicates the device.

The closest in technical essence to the analogue of the invention (prototype) is a known method of preparing the surface of a long cylindrical workpiece for drawing, including applying rosin in the form of a lubricant coating to the surface of the workpiece, followed by applying a powder lubricant to it (see, for example, RF patent No. 21118212 , MKI B 21 C 9/00, publ. 08/27/98, bull. No. 24) / 4 /.

A device for implementing the method comprises a closed chamber having a bath with material in its lower part, including rosin, means for drawing the workpiece through the chamber above this bath, and input and output wiring in front of and behind the camera / ibid /.

In the known method, the application of a lubricating coating is carried out by sublimating the rosin in the bath in the form of a resin, and depositing the resulting drip-liquid resin suspension on the surface of the workpiece. Rosin is one of the varieties of resins, i.e. thermoplastic substance of high molecular weight. In this case, the temperature of sublimation of rosin is lower than the temperature of its chemical decomposition.

A distinctive feature of the resins is their high adhesive ability (stickiness) and high viscosity. Such properties of the resins predetermine the effectiveness of their use as a lubricant coating, which should bind the powdered lubricant to the surface of the metal of the workpiece and hold it under conditions of high shear stresses in the deformation zone during drawing.

Generally, large molecular weight resins are in solid form at normal temperature. The most accessible of the number of suitable natural resins is rosin, obtained from gum juice of coniferous trees, which contains 80 ... 92% resin acids, 0.5 ... 12% saturated and unsaturated fatty acids, 8 ... 20% unsaponifiable compounds; softening temperature 40 ... 75 ° С, melting point - 100 ... 140 ° С (Ed. by Kunyantsa I.L. Chemical Encyclopedia in 5 volumes, - M .: Publishing House "Soviet Encyclopedia", 1988 g., vol. 2, p. 310) / 5 /.

Rosin is usually used in technology as a flux for soldering metal compounds with low-melting tin-containing solders. Exceptional “metallophilicity” of rosin is used: when it spreads over the surface of a metal heated above the rosin's melting point, it separates the oxide film and any impurities from it, and insulates the metal from re-oxidation in air, i.e. creates conditions for successful tinning of metal by solder. Thus, rosin is extremely well bound to metal, exhibiting the properties of a surfactant due to its "acidic" nature. This quality of rosin is used in the prototype method.

The disadvantage of the prototype method is its unsuitability for the subsequent drawing of high-strength metals - high-alloy (stainless) steels, titanium, tantalum, osmium, tungsten, molybdenum, etc. due to the too thin and unstable in thickness and continuity of the lubricating coating obtained by sublimation and deposition. In addition, rosin after sublimation is deposited not only on the surface of the workpiece, but also on the inner surface of the chamber, in which the process of applying a lubricant coating is underway, which leads to unnecessary cost overrun of rosin.

The disadvantage of the prototype device is its complexity, since it additionally contains heating means for sublimating rosin.

The objectives of the invention are:

- in terms of the method - increasing the efficiency of the process of drawing high-strength metals by increasing the thickness and increasing the degree of continuity of the lubricant coating, as well as saving lubricant - rosin;

- in terms of the device - simplification of the design, the exclusion of heating means from it.

In terms of the method, these tasks are solved in that in the method of preparing the surface of a long cylindrical workpiece for drawing, including applying a lubricant coating in the form of rosin on its surface, followed by applying a powder lubricant to it, according to the invention, a lubricating coating is applied by wiping the surface of the workpiece with porous tampons moistened with rosin solution, followed by drying of the solvent, and this is done in a process stream with preliminary mechanical cleaning of the workpieces and from scale and its subsequent dragging.

In terms of the device, these tasks are solved in that the device for preparing the surface of a long cylindrical billet for drawing, including a sealed chamber having in its lower part a bath with material that includes rosin, means for drawing the billet through the chamber above this bath, an introduction and the lead-out wiring in front of and behind the chamber, according to the invention, it is provided with at least two double-roll wiring located in the chamber, sequentially located along the axis of pulling and tiled at different angles to the horizontal, the working surfaces of the rollers are equipped with tampons made of soft and porous material, and rosin liquid solution is used as the material containing rosin, while the lower rollers of each wiring are partially immersed in this solution.

In addition, tampons are made of felt or felt.

In addition, two-roll wiring can be located in mutually perpendicular planes.

In addition, the device may be provided with capillary tubes for supplying rosin solution from the solution preparation chamber to the tampons of the upper rollers.

In addition, the chamber may be equipped with an exhaust device.

In addition, the camera wiring may be provided with a passage pipe connecting the environment to the camera.

In addition, the chamber can be sealed.

The invention consists in the following. Through the use of useful specific properties of rosin and features of the process of applying a lubricant coating, it is possible to achieve a technical result: increasing the efficiency of the drawing process of high-strength metals by increasing the thickness and increasing the degree of continuity of the lubricating coating, while saving material of this coating: rosin. In this case, the process of applying a lubricant coating to the surface of the workpiece is carried out in a stream with preliminary mechanical cleaning and subsequent drawing.

In the device for implementing the method, the high wetting ability of the rosin solution is used, and the softness, porosity and capillarity of the tampon material and the arrangement of two-roll wires at different angles to the horizon contribute to the complete coverage of the workpiece surface with tampons, i.e. its complete wetting with a solution of rosin, and thereby ensure the continuity of the applied coating. Applying a lubricant coating from the solution provides a thicker layer of the substance on the surface of the workpiece in comparison with the prototype method, in which the layer of the lubricant consists of individual microscopic droplets of resin, deliberately unevenly distributed over the surface. For example, when painting surfaces with a roller, a thicker layer is always formed compared to painting from a spray gun (ceteris paribus). Thus, obtained by the method of the invention, the lubricant coating is characterized by a greater thickness and degree of continuity compared to the coating obtained by the prototype method.

The application of a lubricating coating is usually carried out on a surface from which a layer of scale has been previously removed. But such a billet, as a rule, has increased hardness when there is deformation descaling in the cleaning technology, and therefore such a billet is more difficult for subsequent drawing. In addition, the scale located on the surface of the hot-rolled billet or billet, subjected to heat treatment, has significant brittleness, hardness and abrasion. Since after the scale breaker the scale is only partially crumbled, the fine abrasive powder remaining on the surface of the workpiece leads to rapid wear of the drawing tool. A viscous resin grease coating, characterized by increased thickness and continuity, can absorb dusty scale residues on the surface of a mechanically cleaned workpiece and prevent contact of the scale with the drawing tool, thereby contributing to the success of the drawing process of stronger metals, primarily mechanically cleaned of scale.

Resins (including rosin), being thermoplastic substances with high adhesive ability, easily form a film coating upon deformation heating. In addition, rosin has a rather large molecular weight, which provides the coating with the necessary viscosity. During the drawing process, a very viscous, resinous lubricant coating firmly bonded to the metal surface perceives and retains the technological lubricant (mainly powder) applied to it, which also makes it possible to increase the efficiency of the process of drawing a workpiece of high-strength metals.

Two-roller wiring installed in the chamber of the device for implementing the method have rollers with work surfaces coated with felt, felt or the like. Due to the friction of its side surface against a moving workpiece, the rollers rotate. The lower rollers are partially immersed in a rosin solution poured into the bath in the lower part of the chamber and absorb it with their porous and capillary working surface. These rollers, while rotating, provide wetting of the working surfaces of the upper rollers that are in constant contact with them, and both: the lower and upper rollers of each two-roller wiring ensure constant wiping with wet swabs, i.e. wetting the surface of the workpiece passing between them. The arrangement of the pairs of rollers at different angles to the horizon, in particular, the mutually perpendicular arrangement, and the softness, flexibility of the tampons on the working surfaces of the rollers provide a tight fit and guaranteed wetting of the entire side surface of the workpiece with a rosin solution, i.e. continuity of the lubricant coating on the workpiece.

The rosin solution can be supplied from the original container by capillary tubes directly to the upper rollers, wetting their swabs.

Since some solvents (for example, diethyl ether, abs. Ethanol, acetone, benzene) can have a sharp, unpleasant odor and, when evaporated, adversely affect the mucous membranes of the upper respiratory tract, an exhaust device is provided for aspirating their vapors from the working area.

The device for implementing the method may also be provided with a passage tube through which the workpiece exiting from the device is guided (the direction of drawing the workpiece is shown by a contour arrow). In this case, the air flow is intensified in the immediate vicinity of the surface of the workpiece, which leads to accelerated drying of the solution on the surface, elimination of the formation of droplets of the solution on the surface and partial return of the solution to the bath. This also provides an increase in the degree of continuity of the coating.

The invention is illustrated in the drawing, illustrating a specific example of their use, which shows a diagram of a device for implementing the method.

The method of preparing the surface of a long cylindrical workpiece for drawing is as follows.

Pre-cleaned from scale, the hot-rolled preform 1 is pulled through the chamber 2, containing in its lower part a bath 3 with rosin solution 4. This solution in the form of a lubricant coating is applied with a sufficiently thick layer on the surface of the workpiece 1 by wiping it with wet swabs and then drying. The rosin remaining after removing the solvent during the drying process, having high thermoplastic and adhesive properties, adheres firmly to the surface of the workpiece.

Next, in the process stream, a powdery lubricant is applied to the surface of the workpiece thus prepared for subsequent drawing (these steps are not shown in the drawing).

A device for implementing the method is as follows. Directly in the chamber 2, in the lower part of which rosin solution 4 is poured into the bath 3, two-roller wiring is placed, each consisting of freely rotating (non-driving) rollers: lower 5 and upper 6. The wiring rollers are installed, for example, respectively at 45 ° angles (first wiring) and 135 ° (second wiring) to the horizon. The outer surface of the rollers is tightly adjacent to the workpiece and covered with tampons 7 made of felt or felt, or other similar soft and porous material with capillary properties. The chamber 2 is covered from above by a sealed lid 8 to prevent solvent vapors from entering the atmosphere.

The rollers 5, 6 of one roller wiring are in contact not only through the workpiece 1, but also through tampons 7. This ensures the transfer of rosin solution from the lower rollers 5 to the upper 6 and vice versa during their rotation. Due to the softness, porosity and capillarity of the material of the tampons 7, as well as due to the location of the two-roll wires with an angular turn in relation to one another, the supplied solution moistens the entire surface of the workpiece, whatever its diameter, ensuring the continuity of the lubricating coating.

The device also has an input 9 and output 10 wiring respectively at the input and output of the chamber 2, which are designed in the form of dies to slow down the wear of these holes of the chamber.

The coating is dried by natural evaporation. Due to the specific properties of the solvent (for example, diethyl ether, abs. Ethanol, acetone, benzene), evaporation is carried out intensively and does not require significant time, which allows all surface preparation operations to be carried out in a single process stream with subsequent drawing.

When applying a lubricant coating to the surface of the workpiece, the rosin solution can be supplied from the chamber 11 of its preliminary preparation to the surface of the tampons 7 by capillary tubes 12, the diameter of which is determined by the capillary properties of the solution, and their quantity is determined by the required flow rate of the solution.

In this case, the solution can also be transferred from the bath 3 of the chamber 2 with the same capillary tubes (not shown) to the upper rollers 6, and from it, due to the capillary properties of the tampons, to the lower roller 5.

The chamber of the device for applying a lubricating coating 2 can be connected to an exhaust device (not shown) by means of a pipe 13 with a hose on it, suctioning off solvent vapors, providing quick drying of the product and protecting the space surrounding the chamber from them.

The output wiring 10 of the chamber 2 can be equipped with a passage tube 14, providing intensification of air movement (shown by arrows) near the surface of the workpiece 1 and acceleration, due to this - drying of its surface.

The device operates as follows.

In the bath 3 of the chamber 2 at a level below the axis of the drawn blank 1, pour rosin liquid solution 4, for example, in acetone. Then, using the means of pulling the workpiece (not shown) through the input wiring 9, the roller wiring with the lower 5 and upper 6 rollers of the chamber 2 and the output wiring 10 stretch the workpiece 1, mainly of high-strength material, such as alloy steel, previously passing it through the scale breaker. After the front end of the workpiece is fixed in the pulling device (for example, in a drawing drum, not shown in the drawing), the process of applying rosin liquid solution to the surface of the workpiece begins by wiping with wet swabs 7. In the output wiring 10 and further on the way to the drawing wire the tool (not shown) the liquid solvent is intensively evaporated, leaving on the surface of the workpiece dried highly viscous lubricant layer of rosin. Then, either directly in front of the drawing tool or in a separate device, a layer of technological lubricant is applied to the lubricating coating, mainly powdery, for example, sodium or calcium soap (i.e. powders based on sodium or calcium stearates). The workpiece with the surface thus prepared, on which the grease is firmly held, enters the drawing tool, where it undergoes effective compression and can withstand significant shear stresses.

Thus, the invention allows to increase the efficiency of the process of drawing high-strength metals, including from titanium, tantalum, osmium, stainless steels and other metals by increasing the thickness and increasing the degree of continuity of the rosin grease coating.

The use of inventions in the production of wire and calibrated metal will also make it possible to make wider use of effective and environmentally friendly acid-free (physical, mechanical) methods for removing scale from the surface of long cylindrical rolled products and workpieces as part of production lines combined with drawing mills.

Claims (8)

1. A method of preparing the surface of a long cylindrical workpiece for drawing, including applying a lubricant coating in the form of rosin to its surface, followed by applying a powder lubricant to it, characterized in that the lubricating coating is applied by wiping the surface of the workpiece with porous tampons moistened with rosin solution, followed by drying in the process stream with preliminary mechanical cleaning of the workpiece from scale and its subsequent drawing. 2. A device for preparing the surface of a lengthy cylindrical billet for drawing, including a sealed chamber having in its lower part a bath of material containing rosin, means for drawing the billet through the chamber above the bath and inlet and outlet wires in front and behind the chamber, characterized in that it is equipped with at least two two-roll wires located in the chamber, sequentially located along the axis of pulling and installed at different angles to the horizontal, erhnosti rollers provided with tampons made of soft and porous material, and as the material, which includes the rosin, the rosin used liquid solution, wherein the bottom rollers each wiring are partially immersed in the solution. 3. The device according to claim 2, characterized in that the tampons are made of felt or felt. 4. The device according to claim 2, characterized in that the two-roll wiring is located in mutually perpendicular planes. 5. The device according to any one of claims 2 to 4, characterized in that it is equipped with capillary tubes for supplying rosin solution from the solution preparation chamber to the tampons of the upper rollers. 6. The device according to any one of claims 2 to 4, characterized in that the camera is equipped with an exhaust device. 7. The device according to any one of claims 2 to 4, characterized in that the output wiring of the camera is provided with a passage pipe connecting the environment to the camera. 8. The device according to any one of claims 2 to 4, characterized in that the chamber is sealed.