Packable metal pig

Abstract

The invention can be used in the continuous casting of pigs on a casting conveyor. A packable metal pig having a trapezoidal cross-section has two parallel bases, that is to say a lower smaller base and an upper larger base which is the top surface during casting, as well as longitudinal lateral surfaces and end faces, the lateral surfaces and end faces being slanted. The end faces are formed such as to have shoulders in the upper part of the pig, wherein the lower surfaces of said shoulders are situated at an angle of 3-7° to the horizontal and the shoulders increase in thickness toward the end face of the pig. If a pig is formed without shoulders, the parts of the smaller base that are adjacent the end faces are formed such as to be slanted at an angle of 3-7° to the horizontal. Angling the lower surfaces of the shoulders makes it possible, through vertical shrinkage, for the lower base of the pig to be raised in relation to the mold.

Description

[0001] PACKAGING METAL INGOTS

[0002] Field of technology to which the invention relates

[0003] The invention relates to non-ferrous metallurgy, specifically to the production of small-sized ingots by continuous casting on a casting conveyor into molds, including on automated casting lines. Ingots of the proposed design can be used for the production of aluminum and all known aluminum alloys.

[0004] State of the art

[0005] The production of primary aluminum and aluminum casting alloys (hereinafter referred to as alloys) in the form of small-sized ingots is carried out by pouring the melt prepared in a melting unit into metal molds on a casting conveyor.

[0006] One of the main problems when pouring aluminum alloys into metal molds is the sticking and failure of solidified ingots to fall out of the molds on the casting conveyor. The presence of an unremoved ingot in the mold leads to emergency situations: an emergency stop of the casting process or an emergency operation to remove the ingot as the mold approaches the casting position.

[0007] On standard casting conveyors, extraction occurs when the mold strikes a stop as it turns over on a bend in the conveyor. On automated conveyors, extraction occurs through successive hammer blows on the mold if the ingot fails to eject.

[0008] The following factors influence the extraction of pig iron, in particular: the design of the mold / pig iron, mainly the presence and magnitude of slopes; the quality of the mold, including the surface roughness; the presence and quality of the anti-stick lubricant; technological factors such as the casting temperature, the temperature of the molds, the duration of cooling of the pigs in the molds (the temperature of the extracted pigs). A stackable metal pig iron is known according to the USSR Author's Certificate SU470988, B22D3 / 00, 1971, which has a trapezoidal cross-section with engagement elements on the lateral longitudinal surfaces in the form of protrusions formed by the inner and outer surfaces, and recesses formed by the outer and inner surfaces, respectively, made combined, partially overlapping each other along the height of the pig iron and forming teeth and recesses corresponding in shape to them, limited in the longitudinal direction by transition surfaces.To connect adjacent rows into a stack, the surface of the smaller base of the ingot is provided with alternating protrusions and depressions in a staggered pattern. The drawback of this design is that the inner surface has protrusions, and, correspondingly, the outer surface has recesses for engagement elements on the ingot's longitudinal sides. The presence of deep protrusions and depressions on the ingot leads to considerable difficulties when removing it from the mold.

[0009] A stackable metal ingot is known according to patent RU 2083315, B22D3 / 00, published July 10, 1997. This ingot, adopted as a prototype, has a trapezoidal cross-section with engagement elements on the lateral longitudinal surfaces in the form of projections formed by the inner and outer surfaces, and recesses formed by the outer and inner surfaces, respectively, formed at an angle of 40-50° and combined, partially overlapping each other along the height of the ingot and forming teeth and corresponding recesses, limited in the longitudinal direction. On the longitudinal ends, the ingot has shoulders with a groove for visual inspection of the level of metal poured into the mold. The shoulders have a horizontal lower surface. Another disadvantage is the difficulty of removing the ingot from the mold. A trapezoidal section aluminum ingot that can be packaged is known from patent RU 191783, B22D3 / 00, published on August 21, 2019., comprising shoulders with recesses for the strapping band and engagement elements on the lateral longitudinal surfaces in the form of projections and recesses. The pig is formed from upper and lower bases in the form of truncated pyramids, interconnected to form a protruding surface along the entire perimeter of the pig. The projections of the engagement elements are formed by the lateral surfaces of the upper base, the recesses of the engagement elements are formed by the lateral surfaces of the lower base. A longitudinal recess for the strapping band is formed on the surface of the upper base, and the engagement element, when the recesses and projections are aligned, forms an inclined surface along the entire height of the pig. The pig also has an engagement element, when the recesses and projections are aligned, forming a geometric figure in the form of a rhombus, the recess being 1 / 2 the width of the protruding surface.The disadvantage of this ingot is the lack of slopes in the shoulders with recesses for the strapping tape, which can lead to difficulty in removing it from the mold.

[0010] These ingot designs are aimed at increasing the stability and integrity of the bundle, i.e., securing the ingots together within the bundle. For this purpose, various teeth, projections, and corresponding mirror-like recesses and depressions are created on the ingots. However, under production conditions, numerous projections and depressions on the mold and, consequently, on the ingot, impede the free casting shrinkage of the ingot and, therefore, partially hinder its free removal from the mold.

[0011] The main types of ingots cast on conventional casting conveyors are presented in GOST 11070-74 "Primary Aluminum Ingots" - Fig. 1 (drawings 1, 2, 3). A common drawback of known ingots is the lack of design elements to prevent sticking in the molds. Specifically, the lower surfaces of the shoulders and the bottom are designed as horizontal planes, with no slopes on the shoulders or the bottom surface of the ingot. This ingot design, with minor changes in production parameters or with minor wear on the inner surface of the mold, ultimately leads to sticking of the ingot in the mold.

[0012] Fig. 1 (drawing 4) shows a pig designed by Broshot (France) (article on the launch of the pig production line at RUSAL, New Generation of ICL for Rusal - Aluminum Industrial Today No. 32, September / October, 2006) with very slight slopes. This pig, like its known counterparts, also falls out of the mold poorly.

[0013] The only structural elements of existing pigs that ensure their fall out of the molds are the slopes of the side surfaces, the size of which can vary depending on the specific design of the pig.

[0014] To ensure free removal from the mold, the ingot's side slopes (angles from the vertical) can be increased. However, this will result in a decrease in ingot weight for the same planform dimensions, resulting in a decrease in casting productivity and a significant reduction in ingot quality, as the area of ​​the sprue (top) surface of the ingot increases relative to its volume, and casting defects are concentrated primarily on the sprue surface or in areas close to it. Furthermore, a stack of ingots with smaller slopes becomes less stable and less monolithic. Therefore, this solution is ineffective. It is necessary to simultaneously ensure quality and ease of ingot removal.

[0015] Most standard small-sized pigs have shoulders, such as 15 kg pigs according to GOST 11070, see Fig. 1 (drawings 1, 2, 3), pigs based on the inventions mentioned above, or 22.7 kg pigs produced on the automatic lines of Befes, Brochot, and others. The shoulders on the pig structurally serve as planes for lifting the bundle with forklift forks and for strapping the bundle with tape (rod), see Fig. 6. However, the shoulders also have another important function: providing some lift of the pig relative to the mold. This function is not so obvious and therefore requires clarification.

[0016] When the ingot shrinks vertically, it "hangs" on the shoulders, and the bottom rises relative to the mold. For example, if the massive bottom of the mold is 55 mm above the shoulders, the absolute shrinkage value will be:

[0017] A * p = 5, (1) where A is the height of the massive lower part of the mold,

[0018] 55 * 0.007 = 0.38 mm, where P = 0.007 is the linear shrinkage of pure aluminum upon cooling from 660 to 400 °C (the linear shrinkage of pure aluminum upon cooling to room temperature is 1.7%. When cooling in a mold from 660 to 400 °C, the shrinkage will be approximately 0.7%).

[0019] Disclosure of the essence of the invention

[0020] The objective and technical result of the present invention are to ensure free removal of ingots from the mold without deterioration in quality, reduce the likelihood of ingot jamming in the mold, and, consequently, ensure uninterrupted operation of the casting conveyor, reduce the amount of process waste and defects, and simultaneously improve ingot quality. Furthermore, the proposed ingot design, including the mold, utilizes the natural shrinkage of the metal during cooling to further separate the ingot from the mold.The problem is solved and the technical result is achieved due to the fact that a packaged metal pig (as well as a corresponding mold) of trapezoidal cross-section is proposed, containing two parallel bases - a smaller (lower) and a larger (upper or gating surface), lateral longitudinal surfaces having slopes, ends with slopes of the same magnitude and optionally shoulders on the ends in the upper part of the pig, while the new thing is that in order to facilitate the extraction of the pig from the mold due to the use of longitudinal casting shrinkage, as well as to ensure a more reliable fixation of the strapping bands, the lower surfaces of the shoulders are made with an inclination at an angle of 3 - 7 ° to the horizon with an increase in the thickness of the shoulders towards the end of the pig, and for the version without shoulders, the smaller (lower) base of the metal pig is made with an inclination at an angle of 3 - 7 ° to the horizon. Thus, either the surface of the shoulders or the smaller (lower) base of the ingot is made with a slope.

[0021] In a particular version, to increase the strength of the package, on the smaller (lower) base and the lateral longitudinal surfaces, projections and corresponding recesses are made, ensuring the connection of the ingots into a lock both in a row - horizontally, and between rows - vertically of the package.

[0022] Brief description of the drawings

[0023] Fig. 1 shows standard small-sized pigs according to GOST 11070 (drawings 1, 2, 3) and a pig designed by the company “Broshot” (France) (drawing 4).

[0024] Fig. 2 shows the design of the proposed ingot with a mold in cross section.

[0025] Fig. 3 shows the design of the proposed ingot, where 1 is a trapezoidal section; 2 are projections; 3 is the lower plane of the shoulders.

[0026] Fig. 4 shows a mold for casting the proposed ingot.

[0027] Fig. 5 shows a mold with slopes on the bottom surface. Fig. 6 shows bundles of pigs and an enlarged fragment of the shoulders on a pig.

[0028] Fig. 7 shows an example of making an ingot with shoulders according to the invention.

[0029] Fig. 8 shows an example of making a pig without shoulders according to the invention.

[0030] Implementation of the invention

[0031] The presence of slopes on the lower surface of the shoulders (Fig. 2) allows for more efficient use of the ingot's natural shrinkage process—the reduction in size and volume as the metal cools. Moreover, shrinkage is utilized where it is greatest—at the maximum overall dimension along the ingot's length.

[0032] As the ingot's longitudinal dimensions shrink, the shoulders move toward the center along the "Shrinkage 2" arrows in Fig. 2, simultaneously sliding upward along the mold surfaces that form the underside of the shoulders. The presence of slopes on the ingot and mold causes the entire ingot to rise and detach from the mold bottom. The magnitude of the rise (the vertical leg of the displacement vector) is determined by the absolute value of the shrinkage (the horizontal leg) and the inclination angle of the mold shoulder.

[0033] Example:

[0034] The length of the ingot is 730 mm.

[0035] The absolute value of shrinkage in the longitudinal direction according to formula (1) will be 730 * 0.007 = 5.1 mm - on two sides, on one side 2.55 mm.

[0036] The values ​​of the pig lift at different angles of inclination of the shoulder to the horizon are calculated using formula (1) and are summarized in the following table: Experiments have shown that an inclination of up to 7° is advisable; further increases in inclination lead to increased sliding friction and the possibility of shrinkage cracks. Inclinations of less than 3° contribute insignificantly to ingot separation from the mold and are therefore ineffective.

[0037] When using shoulders with a 7° inclination, the vertical lift of the pig in the mold is 0.31 mm and, taking into account simple vertical shrinkage according to formula (1), is approximately 0.7 mm (0.31 + 0.38 = 0.69 mm), which is sufficient to guarantee the separation of the pig from the mold even taking into account the presence of "undercuts" - protrusions or a relief logo on the bottom, increased roughness of the mold walls, deviations in technology, etc. factors. In addition, the slopes on the shoulders also have the function of ensuring more reliable fixation of the strapping bands, see Fig. 6.

[0038] The proposed pig (as well as the mold for this pig) is shown in the drawing, see Fig. 3. The pig has a trapezoidal cross-section (1) with engagement elements on the lateral longitudinal surfaces in the form of projections (2), with a slope of the lower plane of the shoulders (3). The pig is cast in a mold, see Fig. 4. In the drawing of the mold, the slope is determined by a right triangle with legs of 52.5 and 4 mm. Therefore, the angle is equal to 6°. Projections (2) ensure the adhesion of the pig in the cross-section when laying in a bundle, Fig. 6.

[0039] In addition to shouldered pigs, there are many designs of shoulderless pigs, typically weighing less (6 to 12 kg) than shouldered pigs. To ensure removal of these shoulderless pigs from the mold, it is recommended to incline the bottom surface by 3-7° (see Fig. 5). Specifically, the smaller (lower) base of the pig is inclined at an angle of 3-7° to the horizontal.

[0040] The presence of slopes on the bottom surface is especially important for shoulderless pigs, as they lack the lift mechanism described in formula (1) in Fig. 2 or the simple suspension on the shoulders. The mold bottom for such pigs is designed with a rise toward the center at the DU, creating an effect similar to that described above for pigs with inclined shoulders: the pig's longitudinal shrinkage is used to force its vertical movement upward and release it from the mold.

[0041] The angle a (alpha) in the drawings indicates the draft angle. The lower surfaces of the shoulders are inclined to the horizontal at an angle a of 3-7°, with the shoulder thickness increasing toward the end of the ingot. If the ingot is produced without shoulders, the smaller (lower) base of the metal ingot is inclined to the horizontal at an angle a of 3-7°.

[0042] As already noted, it is advisable to use slopes on the bottom surface of up to 7°. Further increases in slope angle lead to increased sliding friction and the possibility of shrinkage cracks. Slopes of less than 3° on the bottom surface contribute insignificantly to ingot separation from the mold and are ineffective.

[0043] Taking into account the description and examples, the scope of legal protection is claimed for a bundled metal ingot of trapezoidal cross-section, containing two parallel bases - a smaller (lower) and a larger (upper or sprue surface), lateral longitudinal surfaces having an inclination, ends with an equal inclination, and in the case of producing an ingot with shoulders on the ends in the upper part of the ingot, the lower surfaces of the shoulders are made with an inclination at an angle of 3 - 7° to the horizon with an increase in the thickness of the shoulders towards the end of the ingot, and in the case of producing an ingot without shoulders, the smaller (lower) base of the metal ingot is made with an inclination at an angle of 3 - 7° to the horizontal. On the smaller (lower) base and lateral longitudinal surfaces, projections and corresponding indentations may be additionally made, ensuring the connection of ingots in a lock both in a row - horizontally, and between rows - vertically of the package.

[0044] This ensures free extraction of the pig from the mold and, accordingly, uninterrupted operation of the casting conveyor, a reduction in the amount of process waste and defects generated, and an increase in the quality of the pig.

Claims

CLAUSES OF THE INVENTION 1. A bundled metal pig of trapezoidal cross-section, containing two parallel bases - a smaller (lower) and a larger (upper or sprue surface), lateral longitudinal surfaces having an inclination, ends with the same inclination, characterized in that in the case of producing a pig with shoulders on the ends in the upper part of the pig, the lower surfaces of the shoulders are made with an inclination at an angle of 3 - 7° to the horizon with an increase in the thickness of the shoulders towards the end of the pig; in the case of producing a pig without shoulders, the smaller (lower) base of the metal pig is made with an inclination at an angle of 3 - 7° to the horizon.

2. A metal pig for packaging according to item 1, characterized in that on the smaller (lower) base and the lateral longitudinal surfaces there are additionally made projections and recesses corresponding to them in shape, ensuring the connection of pigs in a lock both in a row - horizontally, and between rows - vertically of the package.

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