RU2111829C1 - Process of continuous manufacture of thin metal strip and machine for its realization - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: proposed process includes submersion of rotating cooled drum into melt, freezing of melt on it, formation of profile and cutting. Profile on part of working surface and end faces is formed with different intensity of heat removal. Cutting of profile is performed before separation of profile directly on drum. Metal hardened on end faces and edges of drum is again submersed into melt. Machine for realization of process has container for metal with cover, cooled drum and aid for separation of edges. Working surface of drum includes central and peripheral parts. Central part is made of metal and peripheral one - of ceramics, faceplates are installed between them. Aid for separation of edges from strip is manufactured in the form of roller put on levers attached by means of boxes to drum shaft and fitted with disc knives, aid to change distance between cooled drum and roller and aid to move roller over drum circumference. Aid to change distance between drum and roller is fabricated in the form of pneumatic cylinders. EFFECT: energy saving. 6 cl, 5 dwg

Description

 The invention relates to metallurgy.

 The prior art methods for the continuous production of a thin ribbon by feeding molten metal to the surface of a cooled rotating drum with crystallization of the melt on it [1 - 3]. These methods compare favorably with the traditional method of casting slab billets and their subsequent multi-pass rolling in rolling mills with significantly lower energy costs.

 However, the supply of the melt to the surface of the rotating drum from above or from the side necessitates the retention of liquid metal within the length of the drum, which leads to the complication and cost of foundry equipment. In addition, when a strip is formed by known methods, only one size is controlled (strip thickness) and the other is not controlled (strip width), therefore, the uneven edges of the strip obtained as a result of casting are trimmed, which does not allow a sufficiently high yield. For the melting of cut edges, it is necessary to expend additional energy, which leads to a high level of energy consumption.

 There is also known a method of continuously producing a thin metal strip [4], selected as a prototype as the closest in technical essence to the invention. The method includes immersing a rotating drum in a metal receiver filled in a metal receiver, freezing the melt on its working surface and ends, forming a product profile, separating the side edges formed on the ends, feeding them into the melt, removing the strip from the drum and moving outside the metal receiver . The side edges in this process must be cut off, as part of the metal crystallizes on the end surface of the drum, which leads to a deviation of the cross-sectional shape of the strip from a rectangular one. At the same time, it is recommended to create an oxidizing atmosphere in the working space of the metal receiver. The lateral edges of the strip are cut with a plasma arc or using a laser beam.

 A strip is formed on the drum itself, having edges with influxes along the edges formed as a result of freezing of metal on the end surfaces of the drum. A feature of the known process is the trimming of the edges precisely in the process of moving the strip inside the metal receiver, but not on the surface of the drum. In this case, the formation of such a profile is carried out with the same heat removal rate both on the working surface of the drum and near the edges, so metal waste in the form of cut edges is large, and additional energy is required for their subsequent melting.

 Known devices for producing a thin metal strip [1], containing a cooled drum and a roller whose diameter is less than the diameter of the drum. The roller is held at a distance from the surface of the drum, equal to the thickness of the cast strip. The molten metal is fed to the surface of the cooled drum, which is one wall of the mold, and the opposite wall is the surface of the roller. Both the drum and the roller have their own variable speed drives.

 The disadvantage of such devices is the design complexity, since it is required to provide two independent adjustable rotation drives.

 As a prototype device, a machine for continuously producing a metal strip [5] was selected, comprising a metal receiver with a lid, a cooled drum placed on it on the shaft and means for separating the edges from the strip. The machine is also equipped with guides located in a vertical plane, means for trimming the side edges of the strip and heaters. In the upper part of the side walls of the metal receiver, openings are made adjacent to its end wall, while the heaters are installed in the openings and fixed in the cover of the metal receiver, and the guides are located in front of the hole for passing the strip. As means for trimming the lateral edges of the strip and heaters, plasmatrons or lasers are used.

 A disadvantage of the known machine for the continuous production of a metal strip is the need to trim large volumes of edges, since the crystallization of the metal is carried out both from the side of the side surface of the drum and from its ends.

 In contrast to the prototype, it is proposed that the profile on the working surface and at the ends be led with different intensities of heat removal less - from the ends and from the edges of the working surface, and more - from the working surface forming the strip, the side edges are separated from the strip directly on the drum to the separation formed strip from the working surface of the cooled drum, while on the edges separated from the strip, when they are fed into the melt, a portion of the metal is frozen, and then they are melted.

 The formed profile is cut before the profile is separated from the working surface of the cooled drum directly on the drum, and a strip is formed from the profile, which was formed on the drum with a higher heat removal rate, the metal hardened at the ends and edges of the drum is re-immersed in the melt and a portion is transported in the melt the metal is first frozen and then melted.

 The formation of a metal profile with a lower cooling rate along the edges than in the central part of the drum allows avoiding freezing of an excessively thick metal layer at the edges and thereby reduce the energy consumption for the subsequent melting of these wastes.

 Cutting the profile into separate parts before separating it from the surface of the drum, and not after such separation, which is characteristic of the prototype, allows you to use the surface of the drum as an integral part of the cutting tool and refuse such expensive cutting tools as a plasma torch or laser.

 According to the proposed scheme, the metal hardened at the ends and edges of the drum is re-immersed in the melt directly on the surface of the drum, in this case, the melt in contact with the immersed portion of the solid metal is chilled, this leads to freezing of additional metal on the existing one and inducing a skull on this part of the drum to protect the surface of the drum from the effects of the melt. With further rotation of the drum, part of the skull melts and passes into a liquid state.

 The machine for implementing the method includes a metal receiver with a lid, a cooled drum placed on it on the shaft and means for separating the edges from the strip. The difference from the known construction is that the working surface of the drum is made of two parts: the central one is made of a material with high thermal conductivity, for example metal, and the peripheral one is made of a material with low thermal conductivity, for example, ceramic. This allows you to form a thinner layer of metal at the edges of the strip and thereby save energy on re-trimming trim.

 The tool for separating the edges from the strip is made in the form of a roller equipped with circular knives and mounted rotatably on cooled levers attached with axle boxes to the shaft of the cooled drum, while it is equipped with means for changing the distance between the cooled drum and the roller and the means for moving the roller around the circumference drum. This technical solution allows you to have a purely mechanical way of cutting edges and abandon plasmatrons or lasers having a low efficiency. Thus, energy costs are reduced.

 The means for changing the distance between the drum to be cooled and the roller are made in the form of pneumatic cylinders, the bodies of which are fixed with the possibility of movement in the guides on the cooled levers, and the rods are connected to hinges fixed to the axle boxes, connected to the wings, which can swing on the hinges mounted on the cooled levers. This technical solution allows you to remove the drive means of changing the distance from the zone of influence of high temperatures and to ensure the operability of the device when receiving strips of metals with a high melting point.

 At the junction of the central and peripheral parts of the drum, opposite the working edges of the knives, plan washers are made of tool material, for example, heat-resistant steel. Thus, it becomes possible to use the surface of a drum made of relatively fragile material as a tool for cutting the strip, which is especially important if relatively strong material is to be cut.

 The tool for moving the roller around the circumference is made in the form of a pneumatic cylinder, the housing of which is fixed with the possibility of swinging on the metal receiver, and the rod is pivotally mounted on the cooled levers. This made it possible to roll the roller along the surface of the cut and the additional introduction of knives, if with one pass of the knives complete separation of the strip and the edges could not be achieved.

 In FIG. 1 shows a section of the proposed machine for the continuous production of a metal strip in a plane perpendicular to the axis of the drum; in FIG. 2 - enlarged sectional view of the junction of the central and peripheral parts of the cooled drum; in FIG. 3 is a longitudinal section of a means for separating the edges from the strip; in FIG. 4 is a section through a drum and a roller in a plane passing through the axis of the drum and roller; in FIG. 5 - local section of the means for changing the distance between the drum and the roller.

 The proposed machine for the continuous production of a metal strip comprises a metal receiver 1 (Fig. 1) with a cover 2 and a cooled drum 3, mounted rotatably from the drive on the shaft 4. The drum 3 is immersed in the working state of the metal bath 5. As a result of crystallization on the surface a strip is formed of the drum 6. The drum 3 has the ability to move vertically from the drive [4] and the rotation drive [5] (not shown).

 The working surface of the drum is made of two parts: central 7 (Fig. 2) and peripheral 8. The central part 7 is made in the form of an annular bandage from a material with high thermal conductivity, for example, from copper. The latter, together with a sleeve 10 fixed on the hub 9, having an annular groove 11, forms a circular channel for the passage of fluid that cools the central part when the metal is frozen on it. The peripheral part 8 is attached to the hub 9 by means of bolted connections 12 through a steel ring 13. A threaded connection 14 through the washer 15, the ring 13 is also attached to the sleeve 11. The joints are protected from high temperature by a heat-resistant ceramic gasket 16 located in the groove of the peripheral part 8 . Similarly arranged fastening the bandage on its opposite side. In contact with the molten metal bath on the working surface of the drum, a metal layer freezes in the form of a complex cross-section profile: the strip of rectangular cross section 6 itself, the edges of the L-shaped cross section in the form of a thinner part of the strip 17 and part of the metal 18 frozen from the end of the drum. The thinner part of the strip 17 is formed due to the higher heat resistance provided by the peripheral part 8.

 To obtain a commodity strip of rectangular cross-section, a means of separating the edges from the strip is used, which is made in the form of a roller 19 (Fig. 1), mounted for rotation on the cooled levers 20, attached by means of axle boxes 21 to the shaft of the cooled drum 3. Roller 19 (Fig. 3) equipped with circular knives 22 attached to it by bolted joints 23, discs 24 and bushings 25. The roller is mounted on the roller 26 using bushings 27 and 28 and can rotate on bearings 29, mounted by external rings in the levers 20 having cavities 30 for the passage of coolant. The levers 20 are designed as a prefabricated structure using parts 31, 32 and 33. The inner rings of the bearings 29 are secured by a cover using a bolt joint 35.

 When casting tapes from strong materials, the resistance of the surface of the copper drum may not be enough to absorb the cutting force. When casting this kind of materials in working condition, the plan-washers 15 receiving the cutting force 15 are located opposite the working edges of the knives 22 (Fig. 4).

 Means for changing the distance between the cooled drum 3 and the roller 19 is made in the form of pneumatic cylinders 36 (Fig. 1), the housing 37 (Fig. 4) of which are fixed with the possibility of sliding in the rails on the cooled levers 20, and the rods 38 are connected to the hinges fixed to the axle boxes 21 39, having the ability to move along the guide axle boxes 21 vertically and connected to the wings 40, having the ability to swing on hinges 41, mounted on cooled levers 20.

 The means of moving the roller 19 around the circumference (Fig. 1) is made in the form of a pneumatic cylinder, the housing 42 of which, with the help of the bracket 43, is mounted for swinging on the metal receiver 1, and the rod 44 is pivotally mounted on the cooled levers 20.

 The proposed machine works, and the method is as follows.

 The molten metal 5 (Fig. 1) is poured into the metal receiver 1 with a cover 2 and the drum 3 is lowered into the melt to a predetermined depth by rotating it on the shaft 4. As a result of freezing the melt on the surface of the drum, a strip 6 is formed. Due to the circulation of the cooling liquid inside the cavity 11 ( Fig. 2), formed by the sleeve 10 and the Central part 7 of the drum, get a layer of frozen metal of a given thickness. As shown in the drawings, due to the reduced thermal conductivity of the peripheral part 8, the thickness of the frozen metal layer in this region is less, thereby reducing waste to the edge during subsequent removal of the edge. Due to the same reason, a less frozen metal layer from the end face of the drum 18 is also obtained, which also reduces trim. A layer of ceramic packing 16 protects the fasteners 12, 13 and 14 from overheating.

 The edge formed on the drum, having parts 17 and 18, is removed using the roller 19 (Fig. 1), bringing it closer to the surface of the drum, using means for changing the distance between the cooled drum and the roller. To do this, compressed air is supplied to the pneumatic cylinder 36, moving the rod 38 (Fig. 4) up, which causes the roller with knives to move. As a result of the action of the knives 22 on the cast profile, the edge and the strip itself are separated, and this strip is removed from the surface of the drum by winding onto a receiving device (not shown). The edges initially formed on the drum, having parts 17 and 18 (Fig. 2), after separation from the drum of the strip 6, continue to be on the drum, somewhat cooled, make about 3/4 of a turn, and then again immersed in the melt. Depending on the overheating of the melt for three to five revolutions of the drum around its axis, the thickness of the edges increases, and the heat flux through them decreases (due to an increase in heat resistance). In the steady state, during the passage of the edges in the melt, an increase in the thickness of the edges initially takes place, then the growth stops, and at the end of the path in the melt, the thickness of the edges decreases by the amount of growth. The process is stabilizing.

 If a metal movement is created in the melt, the washout of the hardened part is accelerated. At the end of the casting, it is advisable to remove the edges from the drum by blowing oxygen.

 If the casting speed is excessively slow, a situation may arise when the profile temperature at the cutting site is too low and, accordingly, the cutting resistance is too high, and the force of pressing the knives to the strip may not be enough to finish the cutting. In this case, a means of moving the roller around the circumference is used. Compressed air is supplied to the pneumatic cylinder 42 (FIG. 1) mounted on the bracket 43. The movement of the rod of the pneumatic cylinder causes the lever 20 to move and the roller 19 to roll along an arc of a circle around the center of the shaft 4 of the drum 3. Since tensile stresses act in the cast profile due to metal shrinkage during crystallization and cooling, the cut obtained during the first exposure expands and the knives enter the next action wider recess. As a result, the action of friction forces on the lateral surface of the knives is eliminated, the contact surface decreases, and the stresses increase accordingly, which leads to the additional introduction of knives deep into the strip.

 The technical result of the invention (in terms of the method) is the absence of freezing of an excessively thick metal layer at the edges and thereby reducing the energy consumption for the subsequent melting of these wastes. Using the surface of the drum as an integral part of the cutting tool allows you to abandon such expensive cutting tools as a plasma torch or laser, and thereby save energy costs and edge trimming operations. Freezing the edges on the surface of the drum leads to the appearance of a skull, which protects the end parts of the drum from the effects of molten metal and its premature failure.

 The technical result from the use of a machine for the continuous production of a metal strip is the freezing of the edges of a smaller thickness than in the machine of the prototype, which saves energy on remelting waste. In addition, the use of means for separating the edges from the strip in the form of a roller with knives allows you to save energy on the power of the laser or plasma torch, having a low efficiency. The use of means for changing the distance between the drum and the roller of the proposed design allows you to reconfigure the device to produce strips with different thicknesses.

Claims (6)

 1. A method for continuously producing a thin metal strip, comprising immersing a rotating drum in a metal receiver, molten in a metal receiver, freezing the melt on its working surface and ends, forming a product profile, separating side edges formed at the ends, feeding them into the melt, removing strip from the drum, and moving outside the metal detector, characterized in that the formation of a profile on the working surface and at the ends is carried out with different intensities of heat removal, less from the ends and from ev of the working surface, and the larger - from the working surface forming the strip, the separation of the side edges from the strip is carried out directly on the drum to the separation of the formed strip from the working surface of the cooled drum, while a portion of the metal is frozen in the melt when they are fed into the melt and then they are melted.  2. A machine for continuously producing a thin metal strip, comprising a metal receiver with a lid, a cooled drum and a means for separating the edges from the strip placed on the shaft, characterized in that the drum is made of two parts, the central one of a material with high thermal conductivity, for example metal, and peripheral - from a material with low thermal conductivity, such as ceramic.  3. The machine according to p. 2, characterized in that the means for separating the edges from the strip is made in the form of a roller equipped with circular knives and mounted for rotation on cooled levers attached by axle boxes to the shaft of the cooled drum, while it is equipped with a means of changing the distance between the cooled drum and the roller and the means for moving the roller around the circumference of the drum.  4. The machine according to p. 3, characterized in that the means for changing the distance between the drum to be cooled and the roller is made in the form of pneumatic cylinders, the bodies of which are mounted with the possibility of movement in guides on the cooled levers, and the rods are connected to hinges fixed to the axle boxes, connected to the wings, with the ability to swing on hinges mounted on cooled levers.  5. The machine according to claim 2 or 3, characterized in that at the junction of the central and peripheral parts of the drum, opposite the working edges of the knives, plan washers are made of tool material, for example, heat-resistant steel.  6. The machine according to p. 3, characterized in that the means of moving the roller around the circumference is made in the form of a pneumatic cylinder, the casing of which is fixed with the possibility of swinging on the metal receiver, and the rod is pivotally mounted on the cooled levers.

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