Strand guide roller for guiding a metal strand in a strand casting plant

Description

field of technology

[0001] The invention relates to a strand guide roller for guiding a metallic strand in a continuous casting plant. State of the art

[0002] In continuous casting, a metal strand formed in a mold is guided, supported, and further cooled in a strand guide. Typically, the partially or fully solidified strand is supported and guided by so-called strand guide rolls. The strand can also be further cooled by cooled strand guide rolls.

[0003] So-called peripherally cooled strand guide rollers are known from the prior art. These often consist of several roller shells arranged on a common rotating shaft, which is supported by roller bearings at its ends and between the roller shells. With peripheral cooling, the inside of the roller shells is cooled directly with a cooling fluid (usually water).

[0004] The bearings of the strand guide rollers are typically housed in bearing blocks cooled by a water circuit. The design must ensure that no water enters the bearings. This is often achieved through a barrier lubrication system, which injects an additional amount of grease into the bearings. This grease is not necessary for the actual function of the rolling bearings and merely prevents water from entering the bearings. To prevent water from entering, the additional grease escapes from the bearings, mixes with the cooling water, and must be removed again, which requires considerable technical effort.

[0005] In the case of strand guide rollers with peripherally cooled roller shells, the roller shells are usually cooled with an additional water circuit, whereby the cooling water is introduced via a separate rotary inlet, which is a complex and sensitive component for the function of the strand guide roller.

[0006] It is also known from AT517521A1 to use a strand guide roller for guiding a metal strand in a continuous casting plant, comprising at least two support blocks (also called bearing blocks) and a fixed axle for the torsionally rigid connection of the support blocks to one another. A roller shell coaxially surrounding an axial section of the axle is cooled via at least one cooling channel for receiving a cooling fluid. The cooling channel is sealed in the axial direction by at least one seal holder, which has at least one dynamic seal (e.g., a sliding ring) on ​​the outside between the seal holder and the roller shell, and at least one static seal (e.g., a pressure-tight weld or an O-ring) on ​​the inside between the axle and the seal holder.Furthermore, the strand guide roller has at least one plain bearing for each roller shell, arranged between the shaft portion surrounded by the roller shell and the roller shell, for supporting the roller shell so that it can rotate about the shaft. Each plain bearing is subjected to the cooling fluid during operation, i.e., the plain bearings are designed to operate in the cooling fluid.

[0007] US2012043047 discloses a roller and a roller assembly for a continuous casting plant with two bearing blocks. The roller is supported by these bearing blocks, with the roller having a rotationally symmetrical roller shell and the roller bearing being arranged within the roller shell.

[0008] Bearing cooling is a critical factor in operation; overheating can lead to bearing damage. Especially if external cooling for the strand guide rollers fails—for example, because nozzles of an external spray cooling system fail—the thermal stress on the bearings can increase due to the strand guide roller heating. However, even with dry cooling, preventing bearing overheating is problematic. Summary of the invention Technical task

[0009] The invention is based on the object of providing a possibility to reliably protect bearings of strand guide rollers with a fixed axis from overheating.

[0010] The object is achieved according to the invention by the strand guide roller according to claim 1.

[0011] Advantageous embodiments of the invention are the subject of the subclaims.

[0012] A strand guide roller according to the invention comprises at least two support blocks, a fixed axle which connects the two support blocks to one another in a torsionally rigid manner and which has a hollow space at least in sections along its longitudinal extent, at least one roller shell coaxially surrounding at least one axial section of the axle, for each roller shell at least one cooling channel for receiving a cooling fluid for cooling the roller shell, characterized in that For each roller shell, at least one, preferably two, bearings, preferably roller bearings, are provided between an axle section surrounded by the roller shell and the roller shell for supporting the roller shell rotatably about the axle. Each bearing is arranged in a bearing support bushing arranged between an axle section surrounded by the roller shell and the roller shell. At least one channel is provided between the bearing support bushing and the roller shell. At least one channel is provided between the bearing support bushing and the axle. At least one channel is provided that connects the cavity in the axle to the channel between the bearing support bushing and the axle. At least one channel is provided that connects the cavity in the axle or the channel between the bearing support bushing and the axle to the channel between the bearing support bushing and the roller shell.and wherein at least one channel is present in the bearing support bush, which connects the channel between the bearing support bush and the axle and / or the channel between the bearing support bush and the roller shell with the cooling channel for receiving a cooling fluid for cooling the roller shell. ,

[0013] The axle may also have a cavity along its entire longitudinal extent.

[0014] Preferably, the cavity or cavities are arranged coaxially centrally, i.e. the longitudinal axis of the axle runs through them.

[0015] The bearing is preferably a rolling bearing; a rolling bearing is preferably a spring bush bearing.

[0016] The bearing support bush is arranged between an axle section surrounded by the roller shell and the roller shell.

[0017] The channel between the bearing support bush and the roller shell is preferably designed to run all the way around the bearing support bush.

[0018] The channel between the bearing support bush and the axle is preferably designed to run circumferentially around the axle.

[0019] If more than one channel connects the cavity in the axle with the channel between the bearing support bush and the axle, or with the channel between the bearing support bush and the roller shell, i.e. if several such channels are present, then they are preferably offset by 180° each in the case of two channels on the circumference, or preferably offset by 120° each in the case of three channels on the circumference, or preferably offset by 90° each in the case of four channels on the circumference.

[0020] The channel connecting the cavity in the axle or the channel between the bearing support bush and the axle with the channel between the bearing support bush and the roller shell may be an extension of the channel connecting the cavity in the axle with the channel between the bearing support bush and the axle.

[0021] The cavities in the axle, the channels between the bearing support bushing and the axle, and the channels between the bearing support bushing and the roller shell are designed to conduct cooling fluid. Cooling fluid directed through the cavities and channels can cool the strand guide roller and its bearings from the inside.

[0022] The cavity in the axle may have plugs that prevent the flow of cooling fluid along its length and thus direct the cooling fluid into the channels.

[0023] The cooling channel for receiving a cooling fluid to cool the roller shell can, for example, be designed as a cavity between the axle and the roller shell.

[0024] Cooling fluid is, for example, water, possibly with additives, for example additives to improve the cooling effect - for example nanofluids -, additives for corrosion protection.

[0025] Seals can be installed between the bearing support bushing and the shaft; these seals serve both to seal the channels and the bearing from each other, and to seal the bearing interior from the outside world outside the strand guide roller. For example, the bearing interior is grease-lubricated – this prevents cooling fluid from penetrating the grease or grease from escaping to the outside world, as well as dirt from entering the bearing interior.

[0026] The bearing support bush is fixed in the roller shell or on the axle, for example by shrinking, welding or gluing.

[0027] The strand guide rollers according to the invention are thus designed as "sleeve rollers" whose roller shells are mounted for rotation around a fixed axis. Such strand guide rollers are simpler in design and therefore more cost-effective and easier to maintain than strand guide rollers with roller shells permanently mounted on a rotating axis. Furthermore, since the strand guide rollers have fixed axes, bearing block cooling can be advantageously eliminated.

[0028] The at least one cooling channel advantageously provides a simple way to achieve peripheral cooling of the strand guide roller, without having to overcome the problems typically associated with the use of rolling bearings and / or rotating shafts. Because the strand guide roller has a fixed shaft, no complex and repair-prone rotary inlet for introducing coolant is required. The peripheral cooling also enables the strand guide roller to be used for dry casting, i.e., without the strand being cooled by spraying it with coolant during continuous casting. Advantageous effects of the invention

[0029] The inventive installation of a bearing support bush, in which channels are formed between the roller shell and bearing support bush, as well as between the bearing support bush and the axle, which are connected to cooling channels for cooling the roller shell and to the hollow space of the axle, allows cooling fluid to be introduced into the strand guide roller via the axle close to the bearing and only used to cool the roller shell after passing through the bearing support bush. The proximity to the bearing ensures that the bearing in the bearing support bush is intensively cooled. Accordingly, it is easier to keep the bearing temperature below a critical range. This can mitigate any negative consequences of an external cooling failure, and dry casting operation is not problematic.

[0030] Preferably, the bearing support bush is made at least partially of a material that has a higher thermal conductivity than the roller shell; for example, by using copper alloys.

[0031] According to one embodiment, a cavity filled with sodium can be provided between the bearing support sleeve and the roller shell; this can contribute to improved cooling of the bearing. Placing a sodium filling in the contact area between the, for example, shrink-fitted bearing support sleeve opens up the possibility of further intensifying heat dissipation from the bearing area. At temperatures of the bearing support sleeve above 100°C, the sodium melts and, with the high thermal conductivity of the liquid sodium, ensures heat dissipation to the part of the roller facing away from the strand or slab. A shrink fit prevents the liquid sodium from escaping.

[0032] A further subject of the present application is the use of a strand guide roller according to the invention for guiding a metallic strand in a continuous casting plant.

[0033] A further subject matter of the present application is a continuous casting plant with several strand guide rollers according to the invention arranged one behind the other.

[0034] One embodiment of the invention provides that several roller shells are arranged one behind the other along the axis.

[0035] If several roller shells are arranged one behind the other along the axis - seen in the longitudinal direction of the axis - there may be, for example, two roller shells, three roller shells, four roller shells, or more than four roller shells.

[0036] This allows the length of the individual roller shells to be reduced, which advantageously simplifies the production and transport of the roller shells and enables the use of moderately designed bearings to support the roller shells on the axle. Furthermore, a strand guide roller with several roller shells arranged one behind the other enables intermediate support of the axle in areas between two adjacent roller shells, thereby reducing deformations caused by the load on the roller shells during operation in a continuous casting plant. If intermediate support is provided, the axle can be designed in several parts; for example, with intermediate support, two axle halves on which two roller shells are arranged one behind the other - viewed in the longitudinal direction of the axle consisting of the two axle halves - adjacent to each other.From a manufacturing perspective, a multi-part design of the axle is advantageous because the individual parts are more compact and easier to manufacture than a long axle.

[0037] A strand guide roller according to the invention is used to guide a metal strand in a continuous casting plant. Not all roller shells necessarily need to be cooled with the cooling fluid.

[0038] A continuous casting plant has several strand guide rollers according to the invention arranged one behind the other with the advantages mentioned above.

[0039] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of exemplary embodiments, which are explained in more detail in conjunction with the drawings. FIG 1shows an end section of an embodiment of a strand guide roller according to the invention schematically and by way of example. FIG 2 shows a section through an embodiment of a bearing support bush schematically and by way of example. FIG 3 shows schematically and by way of example an embodiment of a multi-part axle. FIG 4a and 4b show schematically and by way of example various views of a sectional view through an embodiment of a bearing support bush. FIG 5 shows a section through an embodiment of a bearing support bush schematically and by way of example.

[0040] Figure 1shows an end section of a strand guide roller 1 according to the invention. A support block 10 can be seen, in which a fixed axle 20 is arranged. The axle 20 has a cavity 21. For better clarity, a second support block, which is torsionally rigidly connected via the axle 20, is not shown. The axle section shown is coaxially surrounded by the roller shell 30. A cooling channel 40 for receiving a cooling fluid for cooling the roller shell 30 is provided, here a gap as a cavity between the roller shell 30 and the axle 20. An area with a bearing 50 - for example a rolling bearing such as a spring bushing bearing 51 - for rotatable

[0041] The bearing of the roller shell 30 is shown with a dashed outline. The bearing is arranged between a section of the roller shell 30 and an axle section surrounded by it.

[0042] According to the invention, the bearing is arranged in a bearing support bush 60. The bearing support bush 60 is arranged between a portion of the roller shell 30 and an axle portion surrounded by it.

[0043] A channel 70 is provided between the bearing support bush 60 and the roller shell 30, and a channel 80 is provided between the bearing support bush 60 and the axle 20. A channel 90 is shown connecting the cavity 21 in the axle 20 with the channel 80 between the bearing support bush 60 and the axle 20. An extension 95 of the channel 90 connects the cavity 21 in the axle 20 or the channel 80 between the bearing support bush 60 and the axle 20 with the channel 70 between the bearing support bush 60 and the roller shell 30. A plug 100 is provided in the cavity 21. Cooling fluid, which flows in the direction of an arrow in Figure 1The coolant introduced into cavity 21 from the left flows into channels 70, 80, and 90 because plug 100 prevents flow along the longitudinal extension of the axle. A connection between the channel between the bearing support bush and the axle, and the channel between the bearing support bush and the roller shell with the cooling channel is provided via channel 110.

[0044] Figure 2 shows a section through one embodiment of a bearing support bushing 60. Visible is the circumferential channel 70 between the bearing support bushing 60 and the roller shell (not shown). Visible is the channel 80 between the bearing support bushing 60 and the axle (not shown). Also visible is the channel 110 connecting the channel 80 and the channel 70 with the cooling channel (not shown).

[0045] Figure 3shows schematically and by way of example an embodiment of a multi-part axle 120; the multi-part axle 120 is formed from the two axle halves 121, 122. There is an intermediate support 130 for the two axle halves 121, 122. On the two axle halves 121, 122, two roller shells 140, 150 are arranged one behind the other - viewed in the longitudinal direction of the axle 120 - adjacent to each other. The schematically illustrated four bearing support bushes 160, 170, 180, 190 at the ends of the two axle halves 121, 122 are analogous to Figure 1 and are not described in detail here. The axle halves 121, 122 each have a hollow space at their ends - axle half 121 the two hollow spaces 201, 202, and axle half 122 the two hollow spaces 211, 212. In contrast to a hollow space running along the entire length of the axle halves, which is then analogous to Figure 1would have to be closed with plugs, the provision of two end-side cavity holes is easier to manufacture.

[0046] Figure 4a and Figure 4b show various views of a sectional view through an embodiment of a bearing support bushing 220. Visible is the circumferential channel 230 between the bearing support bushing 220 and the roller shell (not shown). Visible is the channel 240 between the bearing support bushing 220 and the axle (not shown). Also visible is the channel 250 connecting the channel 240 and the channel 230 with the cooling channel (not shown).

[0047] Figure 5 shows schematically a Figure 1 largely analogous embodiment in which a cavity 260 with sodium filling is present between the bearing support bush 60 and the roller shell 30. List of reference symbols

[0048] 1 Strand guide roller 2 Metallic strand 10 Support block 20 Axle 21 Cavity 30 Roller shell 40 Cooling channel 50 Area with a bearing 51 Spring bush bearing 60 Bearing support bush 70 Channel 80 Channel 90 Channel 95 Extension 100 Plug 110 Channel 120 Axle 121 Axle half 122 Axle half 130 Intermediate support 140 Roller shell 150 Roller shell 160 Bearing support bush 170 Bearing support bush 180 Bearing support bush 190 Bearing support bush 201 Cavity 202 Cavity 211 Cavity 212 Cavity 220 Bearing support bush 230 Channel 240 Channel 250 Channel

Claims

1. Strand guiding roller (1) for guiding a metallic strand in a continuous casting facility, comprising - at least two support blocks (10); - a stationary axle (20) which connects the two support blocks (10) to one another in a torsionally stiff manner, and which along its longitudinal extent has at least in portions a cavity (21); - at least one roller jacket (30) which coaxially surrounds at least one axle portion of the axle (20); - for each roller jacket (30) at least one cooling duct (40) for receiving a cooling fluid for cooling the roller jacket (30) ; wherein - there is for each roller jacket (30) at least one bearing, preferably two bearings, preferably rolling bearings, disposed between an axle portion surrounded by the roller jacket (30) and the roller jacket (30), for mounting the roller jacket (30) so as to be rotatable about the axle (20); - wherein each bearing is disposed in a bearing support bushing (60) which is disposed between an axle portion surrounded by the roller jacket (30) and the roller jacket (30); - wherein there is at least one duct (70) between the bearing support bushing (60) and the roller jacket (30), and wherein there is at least one duct (80) between the bearing support bushing (60) and the axle (20); - and wherein there is at least one duct (90) which connects the cavity (21) in the axle (20) to the duct (80) between the bearing support bushing (60) and the axle (20), and there is at least one duct which connects the cavity (21) in the axle (20), or the duct (80) between the bearing support bushing (60) and the axle (20), to the duct (70) between the bearing support bushing (60) and the roller jacket (30); - and wherein there is in the bearing support bushing (60) at least one duct (110) which connects the duct (80) between the bearing support bushing (60) and the axle (20), and / or the duct (70) between the bearing support bushing (60) and the roller jacket (30), to the cooling duct (40) for receiving a cooling fluid for cooling the roller jacket (30).

2. Strand guiding roller according to Claim 1, wherein the bearing is a rolling bearing, preferably a spring bushing bearing (51).