Rolling mill stand and method of replacing its work roll assembly

Abstract

A rolling mill stand (400) for rolling a metal product (P') comprises, among other things, a first movable rail (414) and a second movable rail (416) arranged to allow the work roll chocks (506, 508) of the upper and lower work rolls (504) to move unhindered when in an idle position during a rolling operation and to allow the replacement of the upper and lower work rolls (504) when in a service position. Methods are provided for moving the first and second movable rails (414, 416) between the idle and service positions in order to replace the upper and lower work rolls (504).

Description

Technical Field

[0001] The present invention relates to a mill stand for rolling metal products and a method for replacing the work roll assembly of the mill stand. Background Technology

[0002] Rolling mills for hot-rolled or cold-rolled metals typically comprise one or more mill stands. Within a mill stand, a work roll assembly comprises two elongated work rolls, arranged horizontally above each other. The working surfaces of the work rolls are separated by a gap. In use, a coil (e.g., metal strip) is formed by passing through the work rolls in a generally horizontal orientation and along a direction of travel perpendicular to the longitudinal axis of the work rolls.

[0003] Properly setting the gap between the work rolls is crucial for efficient operation and product quality. The absolute gap must be the correct size to achieve the desired strip thickness. Furthermore, it is important to maintain a uniform gap size along the length of the work rolls. If the gap size is not substantially uniform along the length (i.e., causing a difference in gap size between the left and right sides of the work rolls), the target strip thickness will not be achieved within the desired length when the strip begins to pass through the work rolls.

[0004] When the work rolls are new, each of them has its maximum diameter. During operational service, the working surfaces of the work rolls tend to wear down over time, causing the diameter of each work roll to decrease. As the work rolls gradually wear down, their axes must be brought closer together to maintain the desired clearance between their surfaces. Eventually, the work rolls will reach their wear limit, at which point they are at their minimum diameter. At this stage, the work rolls can be removed from the mill stand and replaced with a new pair of work rolls. The worn work rolls are removed from the mill stand in the axial direction (i.e., transverse to the rolling direction of the metal strip). The removal process is then performed in reverse to install the replacement work rolls.

[0005] It is desirable to replace the work roll assembly while the metal strip is still in the mill. This avoids the need to cut the metal strip before removing the work roll assembly and to re-manufacture the strip after installing the replacement work roll assembly, thereby advantageously reducing the amount of time spent on replacement and the amount of mill downtime during the replacement process. In the case of a mill with multiple mill stands, it is also desirable to be able to continue rolling the metal strip while the work roll assembly of one or more mill stands is being replaced. This completely eliminates the need to remove the strip from the mill to replace the work roll assembly of any given mill stand, thereby improving operational efficiency.

[0006] Changing the work roll assembly while the metal strip is present in the mill (sometimes referred to as "strip-in-the-mill") requires separating the work roll from the metal strip before pulling it out of the mill stand in the lateral direction to avoid damaging the metal strip or interrupting the rolling process. Therefore, designers must devise various methods to separate the work roll from the metal strip and remove it from the mill stand. The solution to this problem depends heavily on the kinematic configuration of the specific mill stand, as mill stand designs vary depending on the manufacturer and application. For example, an upper rail or similar can be provided to allow the upper work roll to move laterally over the metal strip. Furthermore, the configuration of a given mill stand can be modified from time to time, for example, to improve its design and performance over the mill's service life. Some of these structural modifications can lead to difficulties in changing the work roll assembly of the mill stand. This invention aims to mitigate these problems.

[0007] US 2019 / 022722 A1 discloses a rolling mill for rolling metal strip, the mill having fixed tracks for roll bearing housings for an upper work roll and a lower work roll. A hydraulic bending jack is disposed between the roll bearing housings. Furthermore, a system is disclosed for clamping the work roll bearing housings along the axis of the roll while allowing the bearing housings to slide along a guide following a clamping plane. This system includes a mechanical unit using the closing movement of a retaining cage to switch from a retracted position (allowing the work roll to be withdrawn from the retaining cage along its axis) to a locked position (ensuring the locking of the bearing housings). Summary of the Invention

[0008] According to an aspect of the invention, a rolling mill stand for rolling metal products is provided, the rolling mill stand comprising: a first support and a second support, spaced apart from each other in an X-axis dimension, each support defining a window extending in a Y-axis dimension perpendicular to the X-axis dimension, each window including opposing upper channel forming portions and opposing lower channel forming portions; upper fixed rails, each upper fixed rail extending in the X-axis dimension between a corresponding one of the opposing upper channel forming portions of the first support and a corresponding one of the opposing upper channel forming portions of the second support; and lower fixed rails, each lower fixed rail extending in the X-axis dimension between a corresponding one of the opposing lower channel forming portions of the first support. Extending between corresponding lower channel forming portions of the second support member; a work roll assembly comprising an upper work roll and a lower work roll, each work roll having a longitudinal axis extending in the X dimension, the upper and lower work rolls being arranged spaced apart to form a gap for receiving metal products for rolling in the Y dimension, both ends of the upper work roll being received by corresponding upper work roll bearing seats, and both ends of the lower work roll being received by corresponding lower work roll bearing seats, each of the upper and lower work roll bearing seats including a curved wing extending in the Y dimension, each of these curved wings including at least one transport element, the curved wing of the upper work roll bearing seat... Each of the wing segments is slidably received in a corresponding one of the opposing upper channel forming portions, and each of the curved wing segments of the lower work roll bearing housing is slidably received in a corresponding one of the opposing lower channel forming portions; work roll bending cylinders, each work roll bending cylinder located in one of the opposing upper channel forming portions or the opposing lower channel forming portions and configured to engage a corresponding one of the curved wing segments, each of these work roll bending cylinders being arranged to be selectively extendable and retractable in the Z dimension perpendicular to each of the X and Y dimensions, so as to raise and lower a corresponding one of the upper and lower work rolls, wherein, with respect to each of the said windows, a first energy... The first and second movable tracks are located at each of the opposing upper channel forming sections or at each of the opposing lower channel forming sections. Each of the first and second movable tracks can move independently in the Y dimension between two positions: an idle position, which is not aligned with the corresponding one of the upper or lower fixed tracks in the X dimension; and a service position, which is aligned with the corresponding one of the upper or lower fixed tracks in the X dimension, wherein: when the first and second movable tracks are in the idle position, the movement of the curved wing in the Z dimension is not hindered by the first and second movable tracks;Furthermore, when the first and second movable tracks are in the service position, they together with their respective fixed tracks form a continuous track for guiding the corresponding transport element of the curved blade in the X dimension, so as to selectively retract the work roll assembly from the mill stand and insert the work roll assembly into the mill stand.

[0009] Movable rails (which can be easily installed in modified or new mill stands) provide both an effective means of replacing work roll assemblies (i.e., when the movable rails are in service) and unimpeded bending of the work rolls during normal rolling operations (i.e., when the movable rails are in idle).

[0010] This invention provides an improved work roll assembly changeover process that includes "strip in the mill" replacement. This implies rapid work roll assembly changeover, thereby reducing downtime and thus increasing mill productivity. Another advantage is improved operator efficiency and safety, as the operator does not need to de-thread the strip of the metal product from the mill stand(s) and re-thread it through the mill stand(s) at each work roll changeover event.

[0011] Furthermore, the solution of this invention has virtually no impact on the footprint of existing rolling mill stands because the track system is essentially contained within the stand's supports. Therefore, the solution is very compact and space-efficient. This is particularly advantageous for "retrofitting" track systems into existing rolling mills, where space for roll-changing systems may be limited.

[0012] With respect to each of the aforementioned windows, the first movable track and the second movable track may be located at each of the opposite upper channel forming portions.

[0013] For each of the aforementioned windows, the first movable track and the second movable track may be located at each of the opposite lower channel forming portions.

[0014] Each of the first and second movable tracks can move independently in the Y dimension as follows: from an idle position to a service position along the longitudinal axis toward the upper or lower work roll; and from the service position to an idle position away from the longitudinal axis away from the upper or lower work roll.

[0015] The mill stand may include hydraulic actuators arranged to move a first movable track and a second movable track between an idle position and a service position.

[0016] The mill stand may include a guide for guiding a first movable track and a second movable track in the Y dimension, while resisting movement of the first movable track and the second movable track in the X dimension.

[0017] The guide may include: one of a complementary ridge and channel or similar structure disposed on the surface of each of the opposing upper channel forming portions or opposing lower channel forming portions and extending in the Y dimension; and the other of a complementary ridge and channel disposed on each of the first movable track and the second movable track and extending in the Y dimension, the ridge being received by the channel.

[0018] The mill stand may include a plurality of extended tracks, each extending in the X dimension from one of the first and second supports, each of these extended tracks being aligned and end-to-end abutting one of the continuous tracks and configured to guide the respective transport element.

[0019] The extended track can form an integral part of one of the first and second supports.

[0020] The extended track can form a portion of the carriage that can move in the X dimension, such that the extended track is aligned and end-to-end abutted with the continuous track.

[0021] The at least one transport element may include wheels.

[0022] According to another aspect of the invention, a method is provided for replacing the work roll assembly of a rolling mill stand as described above, wherein, with respect to each of the windows, a first movable track and a second movable track are located at each of the opposing upper channel forming portions, the method comprising: controlling the retraction of a work roll bending cylinder located in the opposing lower channel forming portion and engaging with the bending wing of a lower work roll bearing housing, thereby lowering the lower work roll in the Z dimension to separate the lower work roll from the metal product and to contact each of the transport elements of the lower work roll bearing housing with a corresponding one of the lower fixed tracks; controlling the retraction of the work roll bending cylinder located in the opposing upper channel forming portion and engaging with the bending wing of the upper work roll bearing housing. The bending cylinder extends, thereby raising the upper work roll in the Z dimension to separate the upper work roll from the metal product and bring each of the transport elements of the upper work roll to a height greater than the corresponding first movable track; each first movable track is controlled to move from an idle position into a service position; the bending cylinder of the work roll, located in the opposite upper channel forming section and engaging with the bending wing of the upper work roll bearing housing, retracts, thereby lowering the upper work roll in the Z dimension so that each of the transport elements of the upper work roll bearing housing contacts the corresponding one of the first movable tracks; each second movable track is controlled to move from an idle position into a service position; force is applied to the work roll in the X dimension. The assembly guides each of the transport elements along a corresponding one of the continuous tracks or a corresponding one of the lower fixed tracks, thereby withdrawing the work roll assembly from the mill stand; provides a replacement work roll assembly; applies force to the replacement work roll assembly in the X dimension to guide each of the transport elements along a corresponding one of the continuous tracks or a corresponding one of the lower fixed tracks, thereby inserting the replacement work roll assembly into the mill stand; controls each of the second movable tracks to move from the service position to the idle position; controls the extension of the work roll bending cylinder located in the opposing upper channel forming section, thereby engaging with the bending wing of the upper work roll bearing seat to raise the upper work roll in the Z dimension, so as to... Each of the transport elements of the upper work roll is lifted away from its corresponding first movable track; each first movable track is controlled to move from a service position to an idle position; the work roll bending cylinder located in the opposite upper channel forming section and engaged with the bending wing of the upper work roll bearing housing is controlled to retract, thereby lowering the upper work roll in the Z dimension to bring it into contact with the metal product; and the work roll bending cylinder located in the opposite lower channel forming section is controlled to extend, thereby engaging with the bending wing of the lower work roll bearing housing to raise the lower work roll in the Z dimension, so as to lift each of the transport elements of the lower work roll away from its corresponding lower fixed track and bring the lower work roll into contact with the metal product.

[0023] According to another aspect of the invention, a method is provided for replacing the work roll assembly of a rolling mill stand as described above, wherein, with respect to each of the windows, a first movable track and a second movable track are located at each of the opposing lower channel forming portions, the method comprising: controlling the retraction of a work roll bending cylinder located in the opposing upper channel forming portion and engaging with the bending wing of an upper work roll bearing seat, thereby lowering the upper work roll in the Z dimension so that each of the transport elements of the upper work roll bearing seat contacts a corresponding one of the upper fixed tracks; controlling the retraction of a work roll bending cylinder located in the opposing lower channel forming portion and engaging with the bending wing of a lower work roll bearing seat, thereby lowering the lower work roll in the Z dimension so that the lower work roll... The roller separates from the metal product and allows the metal product to droop so as to separate from the upper work roller; the work roller bending cylinder located in the opposite lower channel forming section and engaged with the bending wing of the lower work roller bearing housing is controlled to retract or extend, thereby bringing each of the transport elements of the lower work roller bearing housing to a greater height than the corresponding first movable track; each first movable track is controlled to move from the idle position into the service position; the work roller bending cylinder located in the opposite lower channel forming section and engaged with the bending wing of the lower work roller bearing housing is controlled to retract, thereby lowering the lower work roller in the Z dimension so that each of the transport elements of the lower work roller bearing housing contacts the corresponding one of the first movable tracks; each second movable track is controlled to move from the idle position into the service position. The roll assembly is moved into service position; force is applied in the X dimension to the work roll assembly to guide each of the transport elements along a corresponding one of the continuous tracks or a corresponding one of the lower fixed tracks, thereby withdrawing the work roll assembly from the mill stand; a replacement work roll assembly is provided; force is applied in the X dimension to the replacement work roll assembly to guide each of the transport elements along a corresponding one of the continuous tracks or a corresponding one of the upper fixed tracks, thereby inserting the replacement work roll assembly into the mill stand; the work roll bending cylinder located in the opposing upper channel forming section is controlled to extend, thereby engaging with the bending wing of the upper work roll bearing housing to raise the upper work roll in the Z dimension, so as to transport each of the transport elements of the upper work roll. Raise the corresponding one of the upper fixed tracks away from the service position; control each second movable track to move from the service position to the idle position; control the extension of the work roll bending cylinder located in the opposite lower channel forming section, thereby engaging with the bending wing of the lower work roll bearing seat to raise the upper and lower work rolls in the Z dimension so as to raise each of the transport elements of the lower work roll away from the corresponding first movable track; control each first movable track to move from the service position to the idle position; and control the extension of the work roll bending cylinder located in the opposite lower channel forming section and engaging with the bending wing of the lower work roll bearing seat, thereby raising the upper and lower work rolls in the Z dimension so that the lower work roll contacts the metal product and moves the metal product to contact the upper work roll.

[0024] For each of the two methods described above, the metal product can be stationary relative to the mill stand in the Y dimension.

[0025] For each of the two methods described above, the metal product can be in motion relative to the mill stand in the Y dimension. Attached Figure Description

[0026] The invention will now be described by way of example with reference to the accompanying drawings, in which: Figures 1a-1c show a conventional rolling mill stand and its work roll assembly; Figure 1d shows a modified version of a conventional rolling mill stand; and Figures 2a-6 A rolling mill stand and its work roll assembly according to the present invention are shown. Detailed Implementation

[0027] Referring to Figures 1a-1c, a conventional mill stand 100 includes a first support member 102 and a second support member 104 extending vertically (i.e., in the Z dimension in the sense of Figures 1a-1d), the two support members being laterally spaced (i.e., in the X dimension) so as to be parallel to each other (i.e., in the Y dimension). The first support member 102 is located on the operating side (or non-drive side) of the mill stand 100, and the second support member 104 is located on the drive side of the mill stand 100. Each of the first support member 102 and the second support member 104 includes a thick, generally rectangular plate having elongated openings or apertures or windows 102a, 104a extending along and through the support members 102, 104 (i.e., in the X dimension).

[0028] Referring specifically to FIG1b, a plurality of support blocks (or bending / balancing blocks) 102b-102g are provided at the middle portion of the window 102a of the first support member 102. These support blocks (or bending / balancing blocks) protrude inward into the window 102a (i.e., in the Y dimension) to define opposing upper channel forming portions 106a and 106b. Similarly, a plurality of support blocks 104b-104g are provided at the middle portion of the window 104a (not visible in FIG1b) of the second support member 104. These support blocks protrude inward into the window 104a (i.e., in the Y dimension) to define opposing upper channel forming portions 108a and 108b. As can be seen in Figure 1b, each group of the support block, 102b-102d, 102e-102g; 104b-104d, 104e-104g, defines an “E” shape, which can be referred to as an “E” shaped block.

[0029] Referring again to Figures 1b and 1c, the first upper track 110a extends between a corresponding support block 102c in the support block of the first support member 102 and a corresponding support block 104c in the support block of the second support member 104 (i.e., in the X dimension). Similarly, the second upper track 110b extends between another corresponding support block 102f in the support block of the first support member 102 and another corresponding support block 104f in the support block of the second support member 104 (i.e., in the X dimension). Thus, the first upper track 110a and the second upper track 110b are arranged parallel to each other and each extends between a corresponding one in the opposing upper channel forming portion 106a of the first support member 102 and a corresponding one in the opposing upper channel forming portion 108a of the second support member 104 (i.e., in the X dimension).

[0030] In a similar manner, the first lower track 112a extends between a corresponding support block 102d in the support block of the first support member 102 and a corresponding support block 104d in the support block of the second support member 104 (i.e., in the X dimension). Similarly, the second lower track 112b extends between another corresponding support block 102g in the support block of the first support member 102 and another corresponding support block 104g in the support block of the second support member 104 (i.e., in the X dimension). Thus, the first lower track 112a and the second lower track 112b are arranged parallel to each other and each extends between a corresponding one in the opposing lower channel forming portion 106b of the first support member 102 and a corresponding one in the opposing lower channel forming portion 108b of the second support member 104 (i.e., in the X dimension).

[0031] Each of the first upper rail 110a and the second upper rail 110b, and the first lower rail 112a and the second lower rail 112b, is fixed relative to the rest of the structure of the support block and the rolling mill stand 100. That is, each of the first upper rail 110a and the second upper rail 110b, and the first lower rail 112a and the second lower rail 112b, is immovable in each of the X, Y, and Z dimensions.

[0032] The mill stand 100 further includes four extending tracks (not shown) that project outward from one of the first support member 102 and the second support member 104 (i.e., in the X dimension and along one of the –X and +X directions), such that each of the four extending tracks is aligned end-to-end with one of the first upper track 110a and the second upper track 110b or one of the first lower track 112a and the second lower track 112b. Alternatively, a separate carriage comprising the four extending tracks is provided, which is movable (i.e., in the X dimension) to allow each of the four extending tracks to be end-to-end abutted and aligned with one of the first upper track 110a and the second upper track 110b or one of the first lower track 112a and the second lower track 112b (i.e., in the X dimension and along one of the –X and +X directions). In each case, all four extending tracks are constructed of steel.

[0033] Referring now particularly to Figures 1a and 1c, the mill stand 100 further includes a work roll assembly 200 comprising an upper work roll 202 and a lower work roll 204, each work roll having a longitudinal axis extending (i.e., in the X dimension) between a first support member 102 and a second support member 104. The upper work roll 202 and the lower work roll 204 are arranged spaced apart to form a gap for receiving the metal product P for rolling in a direction perpendicular to the longitudinal axis of the upper work roll 202 and the lower work roll 204 (i.e., in the –Y direction in the sense of Figures 1a and 1d) (as indicated by the arrow in Figure 1a).

[0034] Each of the two ends of the upper work roll 202 is received and supported by a corresponding upper work roll bearing housing 206. Each of the upper work roll bearing housings 206 includes a flange portion or curved wing 206a on its opposite side, which extends perpendicularly to the longitudinal axis of the upper work roll 202 (i.e., in the Y dimension) and is received by an opposite upper channel forming portion 106a. Similarly, each of the two ends of the lower work roll 204 is received and supported by a corresponding lower work roll bearing housing 208. Each of the lower work roll bearing housings 208 includes a flange portion or curved wing 208a on its opposite side, which extends perpendicularly to the longitudinal axis of the lower work roll 204 (i.e., in the Y dimension) and is received by an opposite upper channel forming portion 106b.

[0035] Each of the upper work roll bearing housing 206 and the lower work roll bearing housing 208 includes wheels 206b and 208b extending from the bearing housing and having an axis of rotation that extends perpendicularly to the longitudinal axis of the upper work roll 202 or the lower work roll 204 (i.e., in the Y dimension). Each of these wheels is configured to engage the upper surface of a corresponding one of the first upper track 110a and the second upper track 110b, and the first lower track 112a and the second lower track 112b.

[0036] Referring now particularly to Figures 1b and 1c, the mill stand 100 further includes work roll bending cylinders 210, each work roll bending cylinder disposed in a corresponding one of the support blocks 102b-102g, 104b-104g, located at or within one of the opposing upper channel forming portions 106a or the opposing lower channel forming portions 106b. Each of the work roll bending cylinders 210 is configured to engage a corresponding one of the bending wings 206a, 208a and is selectively extendable and retractable in the vertical direction (i.e., in the Z dimension) to raise and lower a corresponding one of the upper work roll 202 and the lower work roll 204. Those skilled in the art will understand that the work roll bending cylinders 210 serve to control the gap (or roll gap) between the upper work roll 202 and the lower work roll 204 during rolling operations.

[0037] Referring again specifically to Figures 1a and 1c, the upper work roll 202 and the lower work roll 204 are each supported by corresponding support rolls 302, 304. The longitudinal axes of the upper work roll 202, the lower work roll 204, and the support rolls 302, 304 lie in a single common plane (a vertical plane in the sense of Figures 1a and 1c). A hydraulic roll load cylinder (not shown) is arranged to apply rolling force to the upper work roll 202 via the corresponding support roll 302. The position of the lower work roll 204 and its corresponding support roll 304 can be set, for example, by a pair of wedges located at the base of the mill stand 100. The upper work roll 202 and the lower work roll 204 are constructed of steel. (The conventional mill stand 100 of Figures 1a-1d is a typical hot rolling mill arrangement. In cold rolling mills, the hydraulic roll load cylinder is often located at the bottom, and the wedges are located at the top. Therefore, those skilled in the art will understand that the positions of the wedges and the hydraulic roll load cylinder can be reversed.)

[0038] The upper work roll 202 and the lower work roll 204 tend to wear out during rolling operations, and therefore they are periodically removed from the mill stand 100 for replacement. The process for removing the work roll assembly 200 is as follows.

[0039] The strip of metal product P is cut or diced at each side of the work roll assembly 200 (i.e., in the Y dimension) in order to release the work roll assembly 200 from the tension of the strip of metal product P.

[0040] The work roll bending cylinder 210 is controlled to retract downwards (i.e., along the –Z direction) into the corresponding support blocks 102b-102g, 104b-104g. Therefore, the upper work roll 202 and the lower work roll 204 are lowered (i.e., along the –Z direction) such that each of the wheels in the upper work roll bearing housing 206 and the lower work roll bearing housing 208 is in static contact with the upper surface of either the first upper track 110a and the second upper track 110b, or the first lower track 112a and the second lower track 112b.

[0041] A thrust or pull force is applied to the work roll assembly 200 in the axial direction (i.e., along the +X or –X direction), for example, manually by an operator or by an automated device, to withdraw the work roll assembly 200 from the side of the mill stand along four extended tracks. Once the work roll assembly 200 has left the mill stand 100 (i.e., in the X dimension), it can be moved aside (i.e., in the Y dimension) to make way for a replacement work roll assembly 200 to be inserted into the mill stand 100. The process for inserting a new work roll assembly 200 can be the reverse of the removal process.

[0042] The mill stand 100 described above can be a single stand, or it can be one of multiple similar mill stands in a mill. The mill can be used for hot rolling or cold rolling.

[0043] Regarding the types of mill stands 100 described above, the inventors have found that it is beneficial to make structural modifications over time, for example, modifications to the upper support member 102 and lower support member 104, the upper work roll bearing housing 206 and lower work roll bearing housing 208, and / or the upper work roll 202 and lower work roll 204, in order to make overall improvements to their design and performance over the service life of the mill. In addition to future mill evolution designs, this may also include “modifying” existing mill stands, wherein the upper support member 102 and lower support member 104, the upper work roll bearing housing 206 and lower work roll bearing housing 208, and / or the upper work roll 202 and lower work roll 204 have modified dimensions, shapes, geometries, strengths, materials, etc.

[0044] Furthermore, in some rolling mill configurations, the spacing between the individual mill stands can be irregular, causing some mill stands to be closer together than others (i.e., in the Y dimension). Therefore, the aforementioned displacement (i.e., in the Y dimension) of the work roll assembly 200 after its removal from the mill stand to remove obstacles for the replacement work roll assembly 200 to be inserted (i.e., in the X dimension) into the mill stand 100 may present problems due to a lack of space (i.e., in the Y dimension) between two adjacent mill stands 100. In such cases, one solution might be to shorten (i.e., in the Y dimension) the bending flanges 206a, 208a of the upper work roll bearing housing 206 and the lower work roll bearing housing 208 to provide more space. This may then require redesigning or repositioning some other parts of the mill stand 100, such as the dimensions or geometry of the opposing upper channel forming portion 106a and the opposing lower channel forming portion 106b, and the position of the work roll bending cylinder 210.

[0045] The inventors have discovered that the factors described above concerning modifications to the mill stand 100 can cause difficulties in the removal and replacement of various parts of the mill stand 100 that facilitate the removal and replacement of the work roll assembly 200, as described below.

[0046] Referring to Figure 1d, when in a new state, each of the upper work roll 202 and the lower work roll 204 has a maximum diameter or radius Rmax, while when in a fully worn state, each of the upper work roll 202 and the lower work roll 204 has a minimum diameter or radius Rmin. Each of the upper work roll 202 and the lower work roll 204 will wear over time, resulting in a gradual transition from the maximum diameter or radius Rmax to the minimum diameter or radius Rmin. As a result, the gap between the upper work roll 202 and the lower work roll 204 tends to become larger. Therefore, the corresponding work roll bending cylinder 210 is controlled to move the upper work roll 202 and the lower work roll 204 (i.e., in the Z dimension) so that their longitudinal axes are closer together to maintain the gap at the correct size for rolling the metal product P.

[0047] As shown in Figure 1d, at some stage of the transition between the maximum and minimum work roll diameters, it may become impossible to move the longitudinal axes of the upper work roll 202 and the lower work roll 204 closer together because each of the wheels 206b in the upper work roll bearing housing 206 impacts a corresponding one of the first and second upper rails 110a and 110b. Therefore, further movement of the upper work roll 202 toward the lower work roll 204 is prevented. This potential “collision” between the wheels 206b and the first and second upper rails 110a and 110b is possible due to the types of mill stand modifications described above. This difficulty must be addressed to realize the benefits of the modification and to enable convenient and efficient replacement of the work roll assembly 200 when the upper work roll 202 and the lower work roll 204 have reached their designed minimum diameter.

[0048] Now for reference Figures 2a-6 The mill stand 400 according to the invention has some structural features that are generally similar to those of the conventional “E” block mill stand 100 described above, as well as some other features that are different and overcome the difficulties mentioned above.

[0049] Therefore, the mill stand 400 of the present invention includes a vertically extending (i.e., in) Figures 2a-6 The first support member 402 and the second support member 404 (in the Z dimension) are laterally spaced (i.e., in the X dimension) so as to be parallel to each other (i.e., in the Y dimension). The first support member 402 is located on the operating side (or non-drive side) of the mill stand 400, and the second support member 404 is located on the drive side of the mill stand 400. Each of the first support member 402 and the second support member 404 includes a thick, generally rectangular plate having an elongated opening or aperture or window 402a, 404a extending along and through the support members 402, 404 (i.e., in the Y dimension). In this example, each of the first support member 402 and the second support member 404 is constructed of steel.

[0050] Special Reference Figure 2b In the middle portion of the window 402a of the first support member 402, a plurality of support blocks 402b-402g are provided, which protrude inward into the window 402a (i.e., in the Y dimension) to define opposing upper channel forming portions 406a and opposing lower channel forming portions 406b. Similarly, in the window 404a of the second support member 404 ( Figure 2bIn the middle portion (not visible in the center), multiple support blocks 404b-404g are provided, which protrude inward into the window 404a (i.e., in the Y dimension) to define the opposing upper channel forming portion 408a and the opposing lower channel forming portion 408b. Figure 2b As can be seen, each group of the support blocks, 402b-402d, 402e-402g; 404b-404d, 404e-404g, defines an "E" shape, which can be referred to as an "E" shaped block.

[0051] Still referencing Figure 2b And also Figure 2a The first upper fixed track 410a is a corresponding support block 402c in the support block of the first support member 402 and the second support member 404. Figure 2a and Figure 2b The second upper fixed track 410b extends between the corresponding support block 404c in the support block of the first support member 402 (not visible in the middle) and the second support member 404 (not visible in the middle). Figure 2a and Figure 2b The first upper fixed track 410a and the second upper fixed track 410b are arranged parallel to each other and extend between a corresponding one of the opposing upper channel forming portions 406a of the first support member 402 and a corresponding one of the opposing upper channel forming portions 408a of the second support member 404 (i.e., in the X dimension). Each of the first upper fixed track 410a and the second upper fixed track 410b extends only partially into the corresponding opposing upper channel forming portion 406a (i.e., in the X dimension) so that the extension is less than the full width of the mill stand 400.

[0052] In a similar manner, the first lower fixed track 412a is in the support block of the first support member 402, corresponding to a support block 402d and the second support member 404. Figure 2a and Figure 2b The second lower fixed track 412b extends between the corresponding support block 404d in the support block of the first support member 402 (not visible in the middle) and the second support member 404 (not visible in the middle). Similarly, the second lower fixed track 412b extends between the corresponding other support block 402g in the support block of the first support member 402 and the second support member 404 (not visible in the middle). Figure 2a and Figure 2bThe first lower fixed track 412a and the second lower fixed track 412b are arranged parallel to each other and extend between a corresponding one of the opposing lower channel forming portions 406b of the first support member 402 and a corresponding one of the opposing lower channel forming portions 408b of the second support member 404 (i.e., in the X dimension). Each of the first lower fixed track 412a and the second lower fixed track 412b extends substantially the full width of the mill stand 400 (i.e., in the X dimension).

[0053] Each of the first upper fixed track 410a and the second upper fixed track 410b, and the first lower fixed track 412a and the second lower fixed track 412b, is fixed relative to the rest of the structure of the support block and the rolling mill stand 400. That is, each of the first upper fixed track 410a and the second upper fixed track 410b, and the first lower fixed track 412a and the second lower fixed track 412b, is immovable in each of the X, Y, and Z dimensions.

[0054] Still for special reference Figure 2b And also Figure 2a At each window 402a, 404a of the first support member 402 and the second support member 404, a first movable track 414 and a second movable track 416 are provided. Each movable track is located at a corresponding position in one of the support blocks 402c, 402f to be positioned within a corresponding position in the opposing upper channel forming portion 406a. Each of the first movable track 414 and the second movable track 416 is elongated and extends in the X dimension. Figure 2a and Figure 2b As shown, each of the first movable track 414 and the second movable track 416 is in an idle position so that it is offset from (i.e., in the Y dimension) and not aligned with (i.e., in the X dimension) the corresponding one 412a in the upper fixed track. In the idle position, each of the first movable track 414 and the second movable track 416 is parallel to the corresponding one 412a in the upper fixed track. In this example, in the idle position, each of the first movable track 414 and the second movable track 416 is located outside (i.e., further along the +Y or –Y direction) of the corresponding one 412a in the upper fixed track.

[0055] In this example, the first upper fixed track 410a and the second upper fixed track 410b, the first lower fixed track 412a and the second lower fixed track 412b, as well as the first movable track 414 and the second movable track 416 are all made of steel.

[0056] In this example, each of the first movable track 414 and the second movable track 416 is connected to a corresponding hydraulic rod or piston 418, which extends from the corresponding outer portion of the first support member 402 in the Y dimension (i.e., perpendicular to the corresponding first movable track 414 and the second movable track 416). Each hydraulic piston 418 is configured to be controllable to extend to drive the corresponding first movable track 414 or the second movable track 416 from an idle position to a service position (i.e., in the Y dimension), thereby aligning with the corresponding one 412a of the upper fixed track (i.e., in the X dimension). In the service position, the corresponding plurality of the first movable tracks 414 and the second movable tracks 416 together with the corresponding one 412a of the upper fixed track form a continuous track that substantially extends the full width of the mill stand 400 (i.e., in the X dimension). Each hydraulic piston 418 is further configured to be controllable to retract in order to drive the corresponding first movable track 414 or second movable track 416 from the service position to the idle position (i.e., in the Y dimension).

[0057] Therefore, each of the first movable track 414 and the second movable track 416 can move independently between two positions (i.e., in the Y dimension): an idle position, wherein the first movable track 414 and the second movable track 416 are not aligned with the corresponding one 412a of the upper fixed track (i.e., in the X dimension) and are parallel to the latter; and a service position, wherein the first movable track 414 and the second movable track 416 are aligned with the corresponding one 412a of the upper fixed track (i.e., in the X dimension). Furthermore, in this example, the first movable track 414 and the second movable track 416 can move independently between the idle position and the service position by reciprocating motion according to the action of the extending and retracting hydraulic piston. In this example, each of the first movable track 414 and the second movable track 416 is immovable in both the X and Z dimensions.

[0058] In this example, a channel 414a is provided on the underside of each of the first movable track 414 and the second movable track 416, extending laterally across the first movable track 414 or the second movable track 416 (i.e., in the Y dimension). Furthermore, the upper surface of each of the corresponding support blocks 402c, 402f is provided with complementary ridges 416a, extending in the same direction as the channel 414a (i.e., in the Y dimension) and being received in a conforming manner within the corresponding channel 414a. Therefore, the channel 414a and the ridge 416a act as guides, allowing and facilitating movement of the first movable track 414 and the second movable track 416 in the Y dimension between idle and service positions, while resisting movement in the X dimension.

[0059] Still for special reference Figure 2a and Figure 2b The mill stand 400 further includes a work roll assembly 200, which includes an upper work roll 502 and a lower work roll 504, each work roll having a longitudinal axis extending (i.e., in the X dimension) between a first support member 402 and a second support member 404. The upper work roll 502 and the lower work roll 504 are arranged spaced apart to form a receiving position for metal product P' perpendicular to (i.e., along) the longitudinal axis of the upper work roll 502 and the lower work roll 504. Figure 2a and Figure 2b The direction of –Y direction in a meaningful sense (such as by) Figure 2b The gap for rolling (indicated by the arrow in the image).

[0060] Each of the two ends of the upper work roll 502 is received and supported by a corresponding upper work roll bearing housing 506. Each of the upper work roll bearing housings 506 includes a flange portion or curved wing 506a on its opposite side, which extends perpendicularly to the longitudinal axis of the upper work roll 502 (i.e., in the Y dimension) and is received by an opposite upper channel forming portion 406a. Similarly, each of the two ends of the lower work roll 504 is received and supported by a corresponding lower work roll bearing housing 508. Each of the lower work roll bearing housings 508 includes a flange portion or curved wing 508a on its opposite side, which extends perpendicularly to the longitudinal axis of the lower work roll 504 (i.e., in the Y dimension) and is received by an opposite upper channel forming portion 406b.

[0061] Each of the upper work roll bearing housing 506 and the lower work roll bearing housing 508 includes wheels 506b and 508b extending from the bearing housing and having a rotation axis that extends perpendicularly to the longitudinal axis of the upper work roll 502 or the lower work roll 504 (i.e., in the Y dimension). Each of the wheels 506b in the upper work roll bearing housing 506 is configured to engage the upper surface of a corresponding one of the first upper fixed track 410a and the second upper fixed track 410b, and the upper surfaces of a corresponding two of the first movable track 414 and the second movable track 416. Each of the wheels 508b in the lower work roll bearing housing 508 is configured to engage the upper surface of a corresponding one of the first lower fixed track 412a and the second lower fixed track 412b.

[0062] Still for special reference Figure 2a and Figure 2bThe mill stand 400 further includes work roll bending cylinders 610, each work roll bending cylinder being disposed in a corresponding one of the support blocks 402b-402g, 404b-404g so as to be located at or within one of the opposing upper channel forming portions 406a or the opposing lower channel forming portions 406b. The work roll bending cylinders 610 are hydraulically operated. Each of the work roll bending cylinders 610 is configured to engage a corresponding one of the bending wings 506a, 508a and is selectively extendable and retractable in the vertical direction (i.e., in the Z dimension) to raise and lower a corresponding one of the upper work roll 502 and the lower work roll 504. Those skilled in the art will understand that the work roll bending cylinders 610 serve to control the gap (or roll gap) between the upper work roll 502 and the lower work roll 504 during rolling operations.

[0063] In this example, the upper work roll 502 and the lower work roll 504 are each supported by a corresponding support roll (not shown in the figure). The longitudinal axes of the upper work roll 502, the lower work roll 504, and the support rolls lie in a single common plane (in... Figures 2a-6 In this example, a hydraulic roll load cylinder (not shown) is arranged to apply rolling force to the upper work roll 502 via a corresponding support roll. The positions of the lower work roll 504 and its corresponding support roll can be set, for example, by a pair of wedges located at the base of the mill stand 400. In this example, the upper work roll 502 and the lower work roll 504 are constructed of steel.

[0064] The upper work roll 502 and lower work roll 504 tend to wear out during rolling operations, and therefore they are periodically removed from the mill stand 400 for replacement. Reference will now be made to... Figures 2a-6 Describes the process for removing and replacing the work roll assembly 500.

[0065] First refer to Figure 2a and Figure 2b Initially, each of the first movable track 414 and the second movable track 416 is in an idle position, and each of the upper work roll bearing housing 506 and the lower work roll bearing housing 508 is supported by a corresponding bending cylinder 610. Furthermore, the strip of metal product P' is positioned in the gap between the upper work roll 502 and the lower work roll 504 to contact them. Therefore, the mill stand 400 is initially positioned for rolling the strip of metal product P'. In this example, the mill stand 400 is used for hot rolling. In other examples, the mill stand 400 can be used for cold rolling. In this example, the strip of metal product P' comprises steel. In other examples, the strip of metal product P' may comprise different metals or metal alloys, such as aluminum or aluminum alloys.

[0066] The rolling operation can be stopped, leaving the strip of metal product P' stationary. Alternatively, the rolling operation can continue, keeping metal product P in motion during the changeover of the work roll assembly 500.

[0067] The work roll bending cylinder 610 supporting the lower work roll bearing housing 508 is controlled to retract downwards (i.e., along the –Z direction) into the corresponding support blocks 402d, 402g. Therefore, the lower work roll 504 is lowered (i.e., along the –Z direction) such that each of the wheels 508b of the lower work roll bearing housing 508 is in static contact with the upper surface of the corresponding one of the lower fixed tracks 412a, 412b. As the lower work roll 504 moves downwards in this manner, it separates from the strip of the metal product P'.

[0068] The work roll bending cylinder 610 supporting the upper work roll bearing housing 506 is controlled to extend upward from the corresponding support blocks 402c, 402f (i.e., along the +Z direction). Therefore, the upper work roll 502 is raised (i.e., along the +Z direction) such that each of the wheels 506b of the upper work roll bearing housing 506 is raised to a height slightly above the upper surface of the corresponding one of the upper fixed tracks 410a, 410b and the upper surfaces of the corresponding first movable track 414 and second movable track 416 (i.e., further above these two upper surfaces along the +Z direction). Furthermore, each bending wing 506a of each upper work roll bearing housing 506 is also above the height of the corresponding upper surface of the upper fixed tracks 410a, 410b and the upper surfaces of the corresponding first movable track 414 and second movable track 416 (i.e., further above these two upper surfaces along the +Z direction).

[0069] As the upper work roll 502 moves upward in this manner, it separates from the strip of the metal product P'. Preferably, the upward movement of the upper work roll 502 (i.e., along the +Z direction) and the downward movement of the lower work roll 504 (i.e., along the –Z direction) occur simultaneously. In this case, the upper work roll 502 and the lower work roll 504 can separate from the strip of the metal product P' substantially simultaneously. Alternatively, the downward movement of the lower work roll 504 can occur before the upward movement of the upper work roll 502. In this case, the strip of the metal product P' is no longer supported by the lower work roll 504, but tends to sag downward in order to separate from the upper work roll 502.

[0070] Next reference Figure 3a and Figure 3bRegarding each of the windows 402a and 404a of the first support member 402 and the second support member 404, the hydraulic piston 418 of each first movable track 414 is controlled to extend to move the first movable track 414 from the idle position into the service position. Since the corresponding wheel 506b of the corresponding upper work roller bearing seat 506 is already set at a position slightly higher than the first movable track 414 (i.e., in the Z dimension), the movement of the first movable track 414 into the service position (i.e., in the Y dimension) is not hindered by the wheel 506b. Furthermore, when the first movable track 414 is located directly below the wheel 506b in the service position, there is a small vertical gap (i.e., in the Z dimension) between the upper surface of the first movable track 414 and the wheel 506b.

[0071] Next reference Figure 4a and Figure 4b Regarding each of the windows 402a, 404a of the first support member 402 and the second support member 404, the work roll bending cylinder 610, which still supports the upper work roll bearing seat 506, is controlled to retract downwards (i.e., in the –Z direction) into the corresponding support blocks 402c, 402f. Therefore, the upper work roll 502 is lowered (i.e., in the –Z direction) such that each of the wheels 506b of the upper work roll bearing seat 506 is lowered and comes into static contact with the upper surface of the corresponding one of the first movable tracks 414. The work roll bending cylinder 610 further and completely retracts so as to be flush with (or slightly below) the surface of the corresponding support blocks 402c, 402f. Thus, the upper work roll 502 is supported (only) by the first movable tracks 414.

[0072] Next reference Figure 5a and Figure 5b Regarding each of the windows 402a, 404a of the first support member 402 and the second support member 404, the hydraulic piston 418 of each second movable track 416 is controlled to extend to move the second movable track 416 from the idle position into the service position. Since the work roll bending cylinder 610 is flush with (or slightly below) the surface of the corresponding support blocks 402c, 402f, the movement of the second movable track 416 into the service position (i.e., in the Y dimension) is not hindered by the work roll bending cylinder 610. Furthermore, when the second movable track 416 is in the service position, it is located directly above the work roll bending cylinder 610 and directly below the corresponding bending wing 506a of the corresponding upper work roll bearing seat 506. Additionally, when the second movable track 416 is in the service position, a small vertical gap (i.e., in the Z dimension) exists between the upper surface of the second movable track 416 and the lower surface of the corresponding bending wing 506a of the corresponding upper work roll bearing seat 506.

[0073] When placed in their service positions as described above, the first movable track 414 and the second movable track 416, together with their respective first upper fixed track 410a or second upper fixed track 410b, form a continuous track that substantially extends the full width (i.e., in the X dimension) of the mill stand 400. Thus, there are parallel first and second continuous tracks associated with the upper work roll 502 and with the lower work roll 504, each of these continuous tracks substantially extending the full width (i.e., in the X dimension) of the mill stand 400.

[0074] In this example, the mill stand 400 further includes four extending tracks (not shown) that project outward from one of the first support member 402 and the second support member 404 (i.e., in the X dimension and along one of the –X and +X directions), such that each of the four extending tracks is aligned (i.e., in the X dimension) and end-to-end abutted with one of the aforementioned continuous tracks. In an alternative example, a separate locomotive or carriage comprising the four extending tracks is provided, which is movable (i.e., in the X dimension) to such that each of the four extending tracks is end-to-end abutted and aligned with one of the aforementioned continuous tracks (i.e., in the X dimension to the operating side). In each case, the four extending tracks are constructed of steel.

[0075] A thrust or pull force is applied to the work roll assembly 500 in the axial direction (i.e., along the +X or –X direction), for example, by manual application by an operator or by an automated device, in order to withdraw the work roll assembly 500 from the operating side of the mill stand 400 along four extended tracks.

[0076] The removal process can be performed in reverse to install a replacement work roll assembly in the mill stand 400, as described below.

[0077] The replacement work roll assembly is moved along four extended tracks (i.e., to the operating side in the X dimension) to insert the work roll assembly into the mill stand 400, such that each of the wheels 506b' of the upper work roll bearing housing rests on the upper surface of a corresponding one of the first movable tracks 414 (each of which is in its service position), and each of the wheels 508b' of the lower work roll bearing housing rests on the upper surface of a corresponding one of the lower fixed tracks 412a, 412b.

[0078] With respect to each of the windows 402a, 404a of the first support member 402 and the second support member 404, the hydraulic piston 418 of each second movable track 416 is controlled to retract so as to move the second movable track 416 from the service position to the idle position.

[0079] With respect to each of the windows 402a, 404a of the first support member 402 and the second support member 404, the work roll bending cylinder 610 is controlled to extend upward from the corresponding support blocks 402c, 402f (i.e., along the +Z direction). Therefore, the upper work roll is raised (i.e., along the +Z direction) such that each of the wheels of the upper work roll bearing seat is raised to a height slightly above the upper surface of the corresponding one of the upper fixed tracks 410a, 410b and the upper surfaces of the corresponding first movable track 414 and second movable track 416 (i.e., further than these two upper surfaces along the +Z direction). Furthermore, each bending wing of each upper work roll bearing seat is also above the height of the corresponding upper surface of the upper fixed tracks 410a, 410b and the upper surfaces of the corresponding first movable track 414 and second movable track 416 (i.e., further than these two upper surfaces along the +Z direction). Thus, the upper work roll is supported (only) by the work roll bending cylinders 610, which engage with the corresponding bending wing of each upper work roll bearing seat.

[0080] With respect to each of the windows 402a, 404a of the first support member 402 and the second support member 404, the hydraulic piston 418 of each first movable track 414 is controlled to retract so as to move the first movable track 414 from the service position to the idle position.

[0081] The work roll bending cylinder 610 supporting the upper work roll bearing housing is controlled to retract downwards (i.e., in the –Z direction). Therefore, the upper work roll is lowered (i.e., in the –Z direction). As the lower work roll moves downwards in this manner, it comes into contact with the strip of the metal product P'.

[0082] The work roll bending cylinder 610, which relates to the lower work roll bearing housing, is controlled to extend upward from the corresponding support blocks 402d, 402g (i.e., along the –Z direction). Therefore, the lower work roll is raised (i.e., along the +Z direction) such that each of the wheels in the lower work roll bearing housing is raised away from the upper surface of the corresponding one of the lower fixed tracks 412a, 412b. As the lower work roll moves upward in this manner, it comes into contact with the strip of the metal product P'.

[0083] Therefore, the strip of metal product P' is positioned in the gap between the upper and lower work rolls to contact them. Thus, the mill stand 400 is in a state for rolling the strip of metal product P'.

[0084] As those skilled in the art will understand, the mill stand 400 includes a controller 700 for controlling the extension and retraction of the work roll bending cylinder 610.

[0085] The hydraulic piston 418 that actuates the first movable track 414 and the second movable track 416 can be connected to the same hydraulic system and controller as the work roll bending cylinder 610, or connected to different hydraulic systems and controllers.

[0086] While each of the upper and lower work roll bearing housings in the above examples includes a wheel, in other examples, the upper and lower work roll bearing housings include different transport elements, such as low-friction blocks or skids. All such transport elements are within the scope of the claimed invention, provided they are configured to engage with the corresponding skids to guide the work roll assembly 200 in and out of the mill stand 100.

[0087] It should be understood that the invention has been described with respect to its preferred embodiments and may be modified in many different ways without departing from the scope of the invention as defined by the appended claims.

Claims

1. A rolling mill stand (400) for rolling metal products (P'), the rolling mill stand comprising: A first support member (402) and a second support member (404) are spaced apart from each other in the X dimension and each support member defines a window (402a, 404a) extending in the Y dimension perpendicular to the X dimension, each window (402a, 404a) including an opposing upper channel forming portion (406a) and an opposing lower channel forming portion (406b). Upper fixed tracks (410a, 410b), each upper fixed track extending in the X dimension between a corresponding one of the opposing upper channel forming portions (406a) of the first support member (402) and a corresponding one of the opposing upper channel forming portions (406a) of the second support member (404); Lower fixed tracks (412a, 412b), each lower fixed track extending in the X dimension between a corresponding one of the opposing lower channel forming portions (406b) of the first support member (402) and a corresponding one of the opposing lower channel forming portions (406b) of the second support member (404); A work roll assembly (500) includes an upper work roll (502) and a lower work roll (504), each work roll having a longitudinal axis extending in the X dimension. The upper work roll (502) and the lower work roll (504) are arranged spaced apart to form a gap for receiving metal products (P') for rolling in the Y dimension. The two ends of the upper work roll (502) are received by corresponding upper work roll bearing seats (506), and the two ends of the lower work roll (504) are received by corresponding lower work roll bearing seats (508). Each of the lower work roll bearing housings (508) includes a curved wing (506a, 508a) extending in the Y dimension, each of the curved wing (506a, 508a) including at least one transport element, each of the curved wing (506a) of the upper work roll bearing housing (506) being slidably received in a corresponding one of the opposing upper channel forming portions (406a), and each of the curved wing (508a) of the lower work roll bearing housing (508) being slidably received in a corresponding one of the opposing lower channel forming portions (406b); The mill stand includes work roll bending cylinders (610), each work roll bending cylinder located in one of the opposing upper channel forming portions (406a) or the opposing lower channel forming portions (406b) and configured to engage a corresponding one of the bending wings (506a, 508a). Each of the work roll bending cylinders (610) is arranged to be selectively extendable and retractable in a Z dimension perpendicular to each of the X and Y dimensions, in order to raise and lower a corresponding one of the upper work roll (502) and the lower work roll (504). Its features are, For each of the windows (402a, 404a), a first movable track (414) and a second movable track (416) are provided, located at each of the opposing upper channel forming portions (406a) or at each of the opposing lower channel forming portions (406b). Each of the first movable track (414) and the second movable track (416) is capable of moving independently between two positions in the Y dimension: an idle position, which is not aligned with the corresponding one of the upper fixed track or the lower fixed track in the X dimension; and a service position, which is aligned with the corresponding one of the upper fixed track or the lower fixed track in the X dimension. And among them: When the first movable track (414) and the second movable track (416) are in the idle position, the movement of the curved wings (506a, 508a) in the Z dimension is not hindered by the first movable track (414) and the second movable track (416); and When the first movable track (414) and the second movable track (416) are in the service position, the first movable track (414) and the second movable track (416) together with the corresponding fixed tracks (410a, 410b, 412a, 412b) form a continuous track for guiding the corresponding transport elements of the curved wings (506a, 508a) in the X dimension to selectively withdraw the work roll assembly (500) from the mill stand (400) and insert the work roll assembly into the mill stand (400).

2. The rolling mill stand (400) according to claim 1, wherein, With respect to each of the windows (402a, 404a), the first movable track (414) and the second movable track (416) are located at each of the opposing upper channel forming portions (406a).

3. The rolling mill stand (400) according to claim 1, wherein, With respect to each of the windows (402a, 404a), the first movable track (414) and the second movable track (416) are located at each of the opposite lower channel forming portions (406b).

4. The rolling mill stand (400) according to any one of claims 1 to 3, wherein, Each of the first movable track (414) and the second movable track (416) can move independently in the Y dimension as follows: The longitudinal axis toward the upper work roll (502) or the lower work roll (504) extends from the idle position to the service position; and The longitudinal axis, which is away from the upper work roll (502) or the lower work roll (504), extends from the service position to the idle position.

5. The mill stand (400) according to any one of claims 1 to 3, comprising a hydraulic actuator (418) arranged to move the first movable track (414) and the second movable track (416) between the idle position and the service position.

6. The mill stand (400) according to any one of claims 1 to 3, comprising a guide for guiding the first movable track (414) and the second movable track (416) in the Y dimension while resisting movement of the first movable track (414) and the second movable track (416) in the X dimension.

7. The rolling mill stand (400) according to claim 6, wherein, The guide includes: One of the complementary ridges (416a) and channels (414a) is disposed on the surface of each of the opposing upper channel forming portions (406a) or the opposing lower channel forming portions (406b) and extends in the Y dimension; and The other of the complementary ridge (416a) and channel (414a) is disposed on each of the first movable track (414) and the second movable track (416) and extends in the Y dimension. The ridge (416a) is received by the channel (414a).

8. The mill stand (400) according to any one of claims 1 to 3, comprising a plurality of extending tracks, each extending in the X dimension from one of the first support (402) and the second support (404), each of the extending tracks being aligned and end-to-end abutting one of the continuous tracks and configured to guide the corresponding transport element.

9. The rolling mill stand (400) according to claim 8, wherein, The extended track forms an integral part of one of the first support member (402) and the second support member (404).

10. The rolling mill stand (400) according to claim 8, wherein, The extended track forms a portion of the carriage that can move in the X dimension, such that the extended track is aligned and end-to-end abutted with the continuous track.

11. The rolling mill stand (400) according to any one of claims 1 to 3, wherein, The at least one transport element includes wheels (506b, 508b).

12. A method for replacing the work roll assembly (500) of a rolling mill stand (400) according to claim 2, the method comprising: The work roll bending cylinder (610), located in the opposite lower channel forming section (406b) and engaged with the bending wing (508a) of the lower work roll bearing housing (508), is retracted, thereby lowering the lower work roll (504) in the Z dimension to separate the lower work roll (504) from the metal product (P') and to bring each of the transport elements of the lower work roll bearing housing (508) into contact with a corresponding one of the lower fixed tracks (412a, 412b); The work roll bending cylinder (610), which is located in the opposite upper channel forming part (406a) and engages with the bending wing (506a) of the upper work roll bearing seat (506), extends, thereby raising the upper work roll (502) in the Z dimension to separate the upper work roll (502) from the metal product (P') and bring each of the transport elements of the upper work roll (502) to a greater height than the corresponding first movable track. Control each first movable track to move from the idle position into the service position; The work roll bending cylinder (610), which is located in the opposite upper channel forming part (406a) and engages with the bending wing (506a) of the upper work roll bearing housing (506), is retracted, thereby lowering the upper work roll (502) in the Z dimension so that each of the transport elements of the upper work roll bearing housing (506) contacts a corresponding one of the first movable tracks (414). Control each second movable track (416) to move from the idle position into the service position; Force is applied to the work roll assembly (500) in the X dimension to guide each of the transport elements along a corresponding one of the continuous tracks or a corresponding one of the lower fixed tracks (412a, 412b), thereby withdrawing the work roll assembly (500) from the mill stand (400). Replacement work roll assemblies are available; Force is applied to the replacement work roll assembly in the X dimension to guide each of the transport elements along a corresponding one of the continuous tracks or a corresponding one of the lower fixed tracks (412a, 412b), thereby inserting the replacement work roll assembly into the mill stand (400); Control each second movable track (416) to move from the service location into the idle location; The work roll bending cylinder (610) located in the opposite upper channel forming section (406a) is extended, thereby engaging with the bending wing of the upper work roll bearing seat to raise the upper work roll in the Z dimension so as to lift each of the transport elements of the upper work roll away from the corresponding first movable track (414). Control each first movable track (414) to move from the service location into the idle location; The work roll bending cylinder (610), which is located in the opposite upper channel forming part (406a) and engages with the bending wing of the upper work roll bearing seat, is retracted, thereby lowering the upper work roll in the Z dimension so that the upper work roll contacts the metal product (P'). as well as The work roll bending cylinder (610) located in the opposite lower channel forming section (406b) is extended, thereby engaging with the bending wing of the lower work roll bearing housing to raise the lower work roll (504) in the Z dimension, so as to lift each of the transport elements of the lower work roll (504) away from the corresponding one of the lower fixed tracks (412a, 412b) and bring the lower work roll (504) into contact with the metal product (P').

13. A method for replacing the work roll assembly (500) of a rolling mill stand (400) according to claim 3, the method comprising: The work roll bending cylinder (610), which is located in the opposite upper channel forming part (406a) and engages with the bending wing (506a) of the upper work roll bearing housing (506), is retracted, thereby lowering the upper work roll (502) in the Z dimension so that each of the transport elements of the upper work roll bearing housing (506) contacts a corresponding one of the upper fixed tracks (410a, 410b); The work roll bending cylinder (610), which is located in the opposite lower channel forming portion (406b) and engages with the bending wing (508a) of the lower work roll bearing housing (508), is retracted, thereby lowering the lower work roll (504) in the Z dimension to separate the lower work roll (504) from the metal product (P') and allowing the metal product (P') to droop to separate from the upper work roll (502); Control the retraction or extension of the work roll bending cylinder (610) located in the opposite lower channel forming portion (406b) and engaged with the bending wing (508a) of the lower work roll bearing housing (508), thereby bringing each of the transport elements of the lower work roll bearing housing (508) to a greater height than the corresponding first movable track. Control each first movable track (414) to move from the idle position into the service position; The work roll bending cylinder (610), which is located in the opposite lower channel forming part (406b) and engages with the bending wing (508a) of the lower work roll bearing housing (508), is retracted, thereby lowering the lower work roll (504) in the Z dimension so that each of the transport elements of the lower work roll bearing housing (508) contacts a corresponding one of the first movable tracks (414). Control each second movable track (416) to move from the idle position into the service position; Force is applied to the work roll assembly (500) in the X dimension to guide each of the transport elements along a corresponding one of the continuous tracks or a corresponding one of the lower fixed tracks (412a, 412b), thereby withdrawing the work roll assembly from the mill stand (400); Replacement work roll assemblies are available; Force is applied to the replacement work roll assembly in the X dimension to guide each of the transport elements along a corresponding one of the continuous tracks or a corresponding one of the upper fixed tracks (410a, 410b), thereby inserting the replacement work roll assembly into the mill stand (400); The work roll bending cylinder (610) located in the opposite upper channel forming section (406a) is controlled to extend, thereby engaging with the bending wing of the upper work roll bearing seat to raise the upper work roll in the Z dimension, so as to lift each of the transport elements of the upper work roll away from the corresponding one of the upper fixed tracks (410a, 410b); Control each second movable track (416) to move from the service location into the idle location; The work roll bending cylinder (610) located in the opposite lower channel forming section (406b) is extended, thereby engaging with the bending wing of the lower work roll bearing seat to raise the lower work roll (504) in the Z dimension so as to lift each of the transport elements of the lower work roll (504) away from the corresponding first movable track (414). Control each first movable track (414) to move from the service location into the idle location; as well as The work roll bending cylinder (610), which is located in the opposite lower channel forming portion (406b) and engages with the bending wing of the lower work roll bearing seat, extends, thereby raising the lower work roll (504) in the Z dimension so that the lower work roll (504) contacts the metal product (P') and moves the metal product (P') to contact the upper work roll.

14. The method according to claim 12 or 13, wherein, The metal product (P') is stationary relative to the mill stand (400) in the Y dimension.

15. The method according to claim 12 or 13, wherein, The metal product (P') is in motion relative to the mill stand (400) in the Y dimension.

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