Casting method of roughing mill stand

Abstract

The invention provides a casting method of a roughing mill stand, which relates to the technical field of casting and comprises the following steps: manufacturing a lower body box type of the roughing mill stand; an upper body box type of the roughing mill frame is manufactured in a cover core assembling mode, a cover core in the upper body box type is composed of a plurality of cover core units with sand mold bodies and built-in core bars, and the built-in core bars are arranged in the sand mold bodies; the upper body box type is arranged at a preset position above the lower body box type, and the upper body box type and the lower body box type are correspondingly assembled in a fastening mode, so that a sand mold is obtained; and molten steel is injected into the sand mold, demolding operation is carried out after water is fully cooled and formed, and the roughing mill frame is obtained. The sand burning problem in the casting process of the roughing mill frame can be avoided, and the casting precision of the roughing mill frame is improved.

Description

Technical Field

[0001] The invention relates to the technical field of casting, and in particular to a casting method for a rough rolling mill frame. Background Art

[0002] The rough rolling stand is a key equipment in steel production, especially the frame arch part of the rough rolling stand, which usually has a large volume and weight. At present, the rough rolling stand is usually cast by the sand box molding method. The upper box mold in the sand box molding is designed with a riser. After the molten steel enters the sand mold cavity through the riser, the upper sand mold will be affected by the buoyancy of the liquid metal (i.e., the lifting force of the box). As the volume of the rough rolling stand increases, the riser also increases, and the buoyancy of the upper box mold of the sand mold increases. In order to prevent the sand mold from floating during the pouring process, a box belt will be set in the sand box, and prefabricated steel bars and sand hooks will be used to connect the box belt.

[0003] Although the above measures can effectively prevent the upper box from being lifted, the operation process is relatively cumbersome. Specifically, the operation process includes the upper mold live material, tying the beater, installing the box belt and sand hook, etc., which takes a lot of time. In addition, due to the limited space of the sand box, the sand mold is restricted by the space when it is compacted, resulting in insufficient compactness, which in turn leads to poor strength of the upper box and easy to produce sand sticking defects. Especially when casting large castings such as thick and large rough rolling stands, the traditional sand box molding has low operating efficiency and cannot effectively solve the problem of sand sticking, which in turn leads to reduced casting accuracy of the rough rolling stand. Summary of the invention

[0004] The problem solved by the invention is to avoid the sand sticking problem in the casting process of the rough rolling mill frame and to improve the casting accuracy of the rough rolling mill frame.

[0005] In order to solve the above problems, the present invention provides a casting method for a rough rolling stand, comprising:

[0006] Making the lower box type of the rough rolling mill stand;

[0007] The upper box of the rough rolling mill frame is manufactured by a cover core assembly method, wherein the cover core in the upper box comprises a plurality of cover core units having a sand mold body and an internal core bone, and the internal core bone is internally installed in the sand mold body;

[0008] Arranging the upper box mold at a preset position above the lower box mold, and assembling it correspondingly with the lower box mold by fastening, to obtain a sand mold;

[0009] The molten steel is injected into the sand mold, and after the molten steel is sufficiently cooled and formed, a demoulding operation is performed to obtain the rough rolling stand.

[0010] Preferably, the cover core is obtained by splicing a plurality of cover core units, and adjacent cover core units are filled with molding sand.

[0011] Preferably, the built-in core bone comprises a support frame formed by a plurality of transverse support rods and a plurality of longitudinal support rods connected by fixed connection, and the plurality of transverse support rods and the plurality of longitudinal support rods are staggered to form the support frame with a rectangular geometric structure.

[0012] Preferably, the fixed connection method includes one of welding and mechanical connection.

[0013] Preferably, a riser for injecting the molten steel is arranged on the cover core unit, and the position of the riser corresponds to the center point of the blank area between the transverse support rod and the longitudinal support rod.

[0014] Preferably, after obtaining the sand mold, the step further comprises:

[0015] Placing a weight assembly on the upper box-shaped body, wherein the weight assembly comprises a first weight layer and a second weight layer;

[0016] The first pressed iron layer is composed of a plurality of first pressed irons distributed in parallel, the second pressed iron layer is composed of a plurality of second pressed irons distributed in parallel, and the second pressed iron layer is arranged on the first pressed iron layer.

[0017] Preferably, the first weight and the second weight are made of one of cast iron and cast steel.

[0018] Preferably, each of the first pressure irons in the first pressure iron layer is arranged at a contact position between two adjacent cover core units and coincides with a position of a built-in core bar in the cover core unit.

[0019] Preferably, the built-in core bone is made of cast steel.

[0020] Preferably, the sand mold is poured with molten steel by using multiple casting ladles at the same time.

[0021] Compared with the prior art, the casting method of the rough rolling stand of the present invention has the following beneficial effects: after the lower body box type of the rough rolling stand is manufactured, the upper body box type of the rough rolling stand is manufactured by the cover core assembly method, which can avoid the problems of cumbersome operation and long time consumption caused by the integral sand mold molding, and the upper body box type manufactured by the cover core assembly method can decompose the complex structure through modular design, reducing the difficulty of manufacturing a single mold; then, due to the limited strength of the molding sand body, the arrangement of the built-in core bone can effectively enhance the strength of the upper body box type, which can avoid the problem of sand sticking caused by insufficient strength of the upper body box type; the upper body box type and the lower body box type are assembled by fastening to improve the overall strength of the molding sand mold; finally, the melted molten steel is injected into the sand mold, and after the molten steel is fully cooled and formed, a demoulding operation is performed to obtain a rough rolling stand casting with high precision, thereby avoiding the problem of insufficient precision of the rough rolling stand casting caused by sand box molding defects. The present invention can avoid the problem of sand sticking during the casting process of the rough rolling stand and improve the casting precision of the rough rolling stand. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic flow chart of a casting method of a rough rolling stand according to an embodiment of the present invention;

[0023] Figure 2 It is a structural schematic diagram of a sand mold in a casting method of a rough rolling stand according to an embodiment of the present invention;

[0024] Figure 3 It is a structural schematic diagram of a sand mold in a casting method of a rough rolling mill frame according to an embodiment of the present invention.

[0025] Description of reference numerals:

[0026] 11-lower body box type; 12-cover core; 121-cover core unit; 1211-riser; 131-first pressure iron; 132-second pressure iron. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0028] Reference to an "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] The rolling mill is the main equipment for steel mills to realize the metal rolling process. It is widely used in the steel industry and can be used to produce pipes, plates, profiles and wires. It is the core equipment of the steel industry. Among them, the frame arch is an important part of the rolling mill, which mainly plays a supporting role and bears all the rolling forces generated during the rolling process. Therefore, the structural design and manufacturing quality of the frame arch have a key impact on the performance and service life of the rolling mill.

[0030] With the continuous advancement of science and technology, the design and manufacturing level of wide and thick plate rolling mills in my country has continued to improve, and the volume and weight of its frame arches have gradually increased. At present, the manufacturing of some frame arches has reached the limit level. For example, the net weight of a single frame arch of some wide and thick plate rolling mills can reach 440 tons, and the total weight of liquid steel is more than 800 tons. It is necessary to use a process of pouring 5 bags of molten steel at the same time to complete the casting. In the casting process of such large-sized castings, the overall modeling of the sand mold and the production of the upper box type have become key links, which put forward higher requirements on modeling accuracy, strength and efficiency.

[0031] For the production of large rough rolling mill blanks, the upper box mold is mostly made of sand box, and the process requires a lot of auxiliary tools and pit time. At the same time, due to the large size of the sand mold and high strength requirements, the upper box mold is prone to sand sticking or deformation due to the high temperature and impact force during molten steel pouring, which in turn affects the quality of the casting. In addition, the complexity of the traditional overall molding method also limits the improvement of casting efficiency to a certain extent, especially when dealing with large-tonnage and large-size castings, the manufacturing difficulty is further increased.

[0032] Therefore, how to effectively solve the problem of sand sticking to the upper box of the sand mold, improve the overall strength and stability of the upper box, and at the same time simplify the molding process and shorten the production cycle to meet the needs of large-scale rough rolling mill casting has become a technical problem that needs to be solved urgently in this field.

[0033] Reference Figure 1 , Figure 2 and Figure 3 The present invention provides a casting method for a rough rolling stand, comprising:

[0034] S11, manufacturing the lower box type 11 of the rough rolling mill stand.

[0035] Specifically, the specific manufacturing steps of the roughing rolling mill include: performing three-dimensional modeling according to the structural characteristics of the lower body box type 11 of the roughing rolling mill, and preparing a lower body box type mold, wherein the lower body box type mold may include a plurality of sand mold parts, and the sand mold parts are fixedly connected by molding sand or other fastening methods to form a complete lower body box type mold frame. The lower body box type mold material is preferably made of high-strength and heat-resistant materials to ensure that no deformation or damage occurs during the pouring of molten steel; after the lower body box type mold is completed, the inner cavity of the mold is filled with high-strength molding sand, and the compaction process is used to ensure that the molding sand body is dense and free of gaps, thereby completing the preparation of the lower body box type 11 of the roughing mill frame.

[0036] S12, the upper box mold of the rough rolling mill frame is manufactured by assembling the cover core 12, wherein the cover core 12 in the upper box mold includes a plurality of cover core units 121 having a sand mold body and an internal core bone, and the internal core bone is internally installed in the sand mold body.

[0037] The upper box type of the rough rolling mill frame includes a cover core 12 assembled from a plurality of cover core units 121, each of which is composed of a sand mold body and an internal core bone. The sand mold body of each cover core unit 121 is supported by high-strength refractory sand, and the internal core bone is arranged according to the structure of the upper box type, and can be made of metal (such as cast steel or alloy steel) to have good mechanical strength and heat resistance. The structure of the internal core bone can adopt a longitudinal or transverse support structure, or a three-dimensional support frame to ensure that the cover core unit 121 will not be deformed or damaged due to the flow of molten steel and thermal expansion during the casting process.

[0038] In one embodiment, the upper box type of the roughing mill frame is manufactured by assembling the cover core 12, which specifically includes:

[0039] Determine the predetermined position of the built-in core bone in the sand box according to the design requirements, fix the prepared built-in core bone at the specified position in the sand box, fill the prepared sand into the sand box and cover the built-in core bone, compact the sand by pressing, vibrating or injecting, so that it tightly surrounds the built-in core bone and forms a predetermined shape; after the sand filling is completed, fully solidify the sand mold body by pressing, heating, etc. to form a solid sand mold structure, and after solidification is completed, remove the sand box, take out the solidified sand mold body, and obtain the cover core unit 121 containing the built-in core bone;

[0040] According to the design requirements of the upper box type of the roughing mill stand, the prepared multiple cover core units 121 are assembled and connected by tight docking or other suitable methods to ensure that there is no obvious gap between the cover core units 121, thereby finally forming the upper box type of the roughing mill stand.

[0041] S13, arranging the upper body box mold at a preset position above the lower body box mold 11, and assembling it corresponding to the lower body box mold 11 by fastening, so as to obtain a sand mold.

[0042] Specifically, step S13 includes:

[0043] According to the design requirements of the rough rolling mill stand sand mold, the preset installation position of the upper body box mold is marked on the upper surface of the lower body box mold 11;

[0044] Use lifting equipment (such as a crane or a mechanical arm) to lift the assembled upper body box to the top of the lower body box 11, and slowly move the upper body box according to the calibrated preset position until its bottom is accurately docked with the top of the lower body box 11;

[0045] After the docking is completed, the fastening components are installed along the contact parts of the upper and lower body box types 11. The fastening components include a number of fasteners (such as bolts, clamps or clips) and corresponding positioning holes or slots, which are used to fix the upper and lower body box types 11 to prevent them from shifting or loosening during the subsequent pouring process. It should be explained that the fastening method here is only for illustration and does not necessarily require a fastening component, as long as the upper body box type can be connected to the lower body box type 11.

[0046] Use mechanical tools (such as torque wrenches) or manually to tighten the fasteners one by one to ensure that each fastening point is firmly connected and evenly stressed;

[0047] After the fastening is completed, the upper box mold and the lower box mold 11 are firmly assembled together to form a complete sand mold.

[0048] S14, injecting the melted molten steel into the sand mold, and after the molten steel is sufficiently cooled and formed, performing a demoulding operation to obtain the rough rolling stand.

[0049] Specifically, the steel material is heated to a predetermined melting temperature in a molten steel smelting device (such as an electric arc furnace or a converter) to ensure that the molten steel is completely melted, and the molten steel is transferred to a casting ladle;

[0050] Move the pouring ladle to above the riser 1211 of the sand mold, and slowly inject molten steel by controlling the inclination angle of the ladle. After the molten steel is filled, place the sand mold in a casting pit or designated area and wait for it to cool naturally to room temperature or close to room temperature. During the cooling process, the molten steel gradually solidifies and takes shape. After cooling is completed, disassemble the sand mold.

[0051] Compared with the prior art, the casting method of the rough rolling mill frame of the present invention has the following beneficial effects: after the lower body box mold 11 of the rough rolling mill frame is manufactured, the upper body box mold of the rough rolling mill frame is manufactured by the cover core 12 assembly method, which can avoid the problems of cumbersome operation and long time consumption caused by the sand mold molding, and the upper body box mold manufactured by the cover core 12 assembly method can decompose the complex structure through modular design, reducing the difficulty of manufacturing a single mold; then, due to the limited strength of the molding sand body, the strength of the upper body box mold can be effectively enhanced by arranging the built-in core bone, which can avoid the problem of sand sticking caused by insufficient strength of the upper body box mold; the upper body box mold and the lower body box mold 11 are assembled by fastening to improve the overall strength of the molding sand mold; finally, the melted molten steel is injected into the sand mold, and after the molten steel is fully cooled and formed, the demolding operation is performed to obtain a rough rolling mill frame casting with higher precision, thereby avoiding the problem of insufficient precision of the rough rolling mill frame casting caused by defects in sand box molding. The present invention can avoid the problem of sand sticking during the casting process of the roughing mill frame and improve the casting accuracy of the roughing mill frame.

[0052] Reference Figure 2 and Figure 3 The cover core 12 is obtained by splicing a plurality of cover core units 121 , and the space between adjacent cover core units 121 is filled with molding sand.

[0053] Specifically, the splicing process of the cover core unit 121 includes: placing the prepared multiple cover core units 121 in a designated position in a predetermined order on a flat splicing platform or sand mold box; each cover core unit 121 should be aligned with the splicing edge to ensure that there is no obvious misalignment or gap between the units; then fill the prepared molding sand at the splicing seam of adjacent cover core units 121. During the filling process, the molding sand can be filled layer by layer manually or mechanically, and the filled molding sand can be compacted using a vibration device to avoid looseness or gaps. After the molding sand is filled, the molding sand is consolidated and formed by curing measures (such as heating, spraying a hardener, or natural curing) to form a firm splicing structure.

[0054] In this embodiment, the splicing between the cover core units 121 can achieve the integrity and sealing of the structure, and the separately prepared cover core units 121 avoids the complicated processes and processes in the sand box molding process (such as: loading live materials, tying beaters, installing box belts and sand hooks, etc.), shortening the preparation time of the upper box mold; on the other hand, the molding sand filling and solidification treatment effectively enhances the strength of the splicing, avoiding the deformation, sand leakage or steel leakage of the cover core 12 caused by loose joints during the subsequent molten steel pouring process, thereby improving the reliability of the casting process and the quality of the finished product.

[0055] In one embodiment, the built-in core bone includes a support frame formed by a plurality of transverse support rods and a plurality of longitudinal support rods that are fixedly connected, and the plurality of transverse support rods and the plurality of longitudinal support rods are staggered to form the support frame with a rectangular geometric structure.

[0056] It should be explained that the size and shape of the support rods can be calculated and adjusted according to the actual requirements of the upper box type of the rough rolling mill frame to ensure that it can withstand the temperature and mechanical stress during the casting process; and the transverse support rods and the longitudinal support rods are welded, bolted or other fixed methods to form an staggered rectangular frame.

[0057] This embodiment adopts a staggered rectangular geometric structure so that the support frame of the built-in core bone can effectively enhance the overall strength and stability of the cover core unit 121. On the one hand, the staggered design enables the support frame to evenly distribute the stress generated during the casting process, preventing the support rod from being subjected to excessive local stress or bending or deformation, thereby ensuring the accuracy and quality of the casting and ensuring the smooth progress of casting.

[0058] Preferably, the fixed connection method includes one of welding and mechanical connection.

[0059] This embodiment ensures a stable connection between the support rods of the built-in core bone by using one of the two methods of welding and mechanical connection. Among them, the welding fixation method is suitable for connection parts that require high-strength fixation, can provide higher connection strength and stability, and is suitable for areas that are subjected to large mechanical stress, while the mechanical connection method is easy to construct and disassemble, has good flexibility, and can be easily maintained and replaced without changing the structure. Either of the two methods can effectively ensure that the support of the built-in core bone is stable and firm during the casting process, avoid structural deformation or defects caused by unstable connection, and thus improve the quality and stability of the casting.

[0060] In one embodiment, a riser 1211 for injecting the molten steel is arranged on the cover core unit 121 , and the position of the riser 1211 corresponds to the center point of the blank area between the transverse support rod and the longitudinal support rod.

[0061] It should be explained that riser 1211 is a component commonly used in the casting process, usually used at the top or specific position of the casting mold. Its main function is to provide molten steel or other molten metal to enter the mold and ensure smooth filling of the casting while preventing the occurrence of casting defects.

[0062] In this embodiment, the center point of the riser 1211 coincides with the central area between the transverse support rods and the longitudinal support rods, which can ensure that the molten steel can be evenly distributed to various parts of the mold during the pouring process, avoiding uneven pressure or fluidity during pouring, and making the setting position of the riser 1211 correspond to the center point of the grid in the support frame (i.e., the area enclosed by the transverse support rods and the longitudinal support rods) so that the molten steel can bypass the support rods of the support frame and evenly enter the various cavities of the mold.

[0063] In one embodiment, after obtaining the sand mold, the method further comprises:

[0064] Placing a weight assembly on the upper box-shaped body, wherein the weight assembly comprises a first weight layer and a second weight layer;

[0065] The first pressed iron layer is composed of a plurality of first pressed irons 131 distributed in parallel, the second pressed iron layer is composed of a plurality of second pressed irons 132 distributed in parallel, and the second pressed iron layer is arranged on the first pressed iron layer.

[0066] The pressure iron assembly in this embodiment is mainly used to reinforce and stabilize the upper box mold to prevent the sand mold from deforming due to the impact force of the molten steel, thermal expansion and other factors during the molten steel injection process; and the pressure iron assembly can ensure the shape and dimensional stability of the sand mold during the casting process of large castings by enhancing the structural strength of the mold.

[0067] Furthermore, the first pressure iron layer is composed of a plurality of first pressure irons 131 distributed in parallel. The arrangement of the first pressure irons 131 is intended to provide uniform external force to compact the sand mold and increase the strength of the sand mold to ensure stability during the casting process. The shape of the first pressure iron 131 can be a long strip, a rectangle or other shapes that are suitable for the sand mold; the second pressure iron layer is arranged above the first pressure iron layer to form a double-layer reinforcement structure to further improve the uniformity and stability of the second pressure iron layer. The second pressure iron layer is arranged to increase the overall strength of the mold and prevent the mold from being excessively deformed during high temperature and molten steel injection.

[0068] The structure of the second pressure iron layer is similar to that of the first pressure iron layer, but the material or size may be different. Usually, the length and width of the second pressure iron 132 are consistent with the first pressure iron 131, but in a larger sand mold, the second pressure iron 132 can be heavier than the first pressure iron 131 to meet the needs of high pressure.

[0069] This embodiment effectively enhances the stability of the upper box mold by setting up a double-layer pressure iron assembly, preventing deformation that may occur during the casting process. Moreover, the design of the first pressure iron layer and the second pressure iron layer makes the pressing pressure of the upper box mold evenly distributed, thereby ensuring the high strength and good casting performance of the sand mold.

[0070] In one embodiment, the first weight 131 and the second weight 132 are made of one of cast iron and cast steel.

[0071] In one embodiment, each of the first pressure irons 131 in the first pressure iron layer is disposed at a contact position between two adjacent cover core units 121 , and coincides with a position of a built-in core bone in the cover core unit 121 .

[0072] Specifically, the first pressure iron layer is composed of a plurality of first pressure irons 131, and the first pressure irons 131 are evenly arranged in the upper box of the sand mold, and each first pressure iron 131 corresponds to the contact part of the adjacent cover core unit 121, and ensures that it coincides with the position of the built-in core bone. This embodiment can ensure that the pressure of the first pressure iron 131 can directly act on the built-in core bone of the cover core unit 121, thereby enhancing the overall strength and compression resistance of the upper box; furthermore, the built-in core bone is an important part of strengthening the structure of the cover core unit 121, and its position corresponds to the position of the first pressure iron 131, so that the role of the built-in core bone is not only to improve the strength of the cover core 12, but also to provide a solid support point for the first pressure iron 131, so that the cover core 12 can withstand greater pressure without deformation.

[0073] In one embodiment, the built-in core bone is made of cast steel.

[0074] In one embodiment, the sand mold is poured with molten steel by using multiple casting ladles simultaneously.

[0075] Specifically, the present embodiment uses multiple casting ladles to simultaneously cast molten steel, which can effectively improve the quality and production efficiency of the rough rolling stand castings; further, multi-point synchronous pouring can ensure the uniform distribution of molten steel, reduce defects such as uneven flow of molten steel, bubbles or voids that may occur during the pouring process, thereby improving the casting strength and precision of the rough rolling stand.

[0076] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, the storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc. In the present application, the unit described as a separate component may or may not be physically separated, and the component displayed as a unit may or may not be a physical unit, that is, it may be located in one place, or it may be distributed on multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiment of the present invention. In addition, each functional unit in each embodiment of the present invention can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0077] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A casting method for a rough rolling stand, characterized in that: include: Make the lower box type of the rough rolling mill stand; The upper box of the rough rolling mill frame is manufactured by a cover core assembly method, wherein the cover core in the upper box comprises a plurality of cover core units having a sand mold body and an internal core bone, and the internal core bone is internally installed in the sand mold body; Arranging the upper box mold at a preset position above the lower box mold, and assembling it correspondingly with the lower box mold by fastening, to obtain a sand mold; The molten steel is injected into the sand mold, and after the molten steel is sufficiently cooled and formed, a demoulding operation is performed to obtain the rough rolling stand.

2. The casting method of the roughing mill stand according to claim 1, characterized in that: The cover core is obtained by splicing a plurality of cover core units, and the space between adjacent cover core units is filled with molding sand.

3. The casting method of the roughing mill stand according to claim 1, characterized in that: The built-in core bone includes a support frame formed by a plurality of transverse support rods and a plurality of longitudinal support rods that are fixedly connected, and the plurality of transverse support rods and the plurality of longitudinal support rods are staggered to form the support frame with a rectangular geometric structure.

4. The casting method of the roughing mill stand according to claim 3, characterized in that: The fixed connection method includes one of welding and mechanical connection.

5. The casting method of the roughing mill stand according to claim 3, characterized in that: A riser for injecting the molten steel is arranged on the cover core unit, and the position of the riser corresponds to the center point of the blank area between the transverse support rod and the longitudinal support rod.

6. The casting method of the roughing mill stand according to claim 3, characterized in that: The sand mold is obtained and the following steps are also included: Placing a weight assembly on the upper box-shaped body, wherein the weight assembly comprises a first weight layer and a second weight layer; The first pressed iron layer is composed of a plurality of first pressed irons distributed in parallel, the second pressed iron layer is composed of a plurality of second pressed irons distributed in parallel, and the second pressed iron layer is arranged on the first pressed iron layer.

7. The casting method of the roughing mill stand according to claim 6, characterized in that: The first weight and the second weight are made of one of cast iron and cast steel.

8. The casting method of the roughing mill stand according to claim 6, characterized in that: Each of the first pressure irons in the first pressure iron layer is arranged at a contact position between two adjacent cover core units and coincides with a position of a built-in core bar in the cover core unit.

9. The casting method of a roughing mill stand according to claim 1, characterized in that: The built-in core bone is made of cast steel.

10. The casting method of a roughing mill stand according to claim 1, characterized in that: The sand mold is poured with molten steel by using a plurality of pouring ladles simultaneously.

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