Indirect chilling block of wind power bearing seat and drawing fixing system comprising indirect chilling block

Abstract

The indirect chilling block of the wind power bearing seat and the drawing fixing system comprising the indirect chilling block structurally comprise a cylindrical chilling block body, a plurality of vertically-extending sand hanging grooves are formed in the peripheral side wall of the cylindrical chilling block body, a gap is formed between the cylindrical chilling block body and a wind power bearing seat mold, and the gap is filled with molding sand. A tie bar is arranged on one axial end face of the cylindrical chilling block body; the scheme of the utility model has the advantages that no extra sand core needs to be arranged, the stability of the fixed position can be ensured, and the size of the obtained casting is accurate.

Description

Technical Field

[0001] The present application relates to the field of casting technology for castings used in the field of wind energy, and particularly to an indirect chill for a wind power bearing seat and a drawing and fixing system containing the same. Background Art

[0002] With the rapid development of the wind power industry, the demand for ductile iron fittings for wind power has increased rapidly, and the ductile iron used for wind power has developed rapidly. Due to its low cost and high strength and toughness, ductile iron has been widely used at home and abroad. However, compared with ordinary ductile iron, higher quality and performance requirements are imposed on wind power castings because the working environment of wind turbines is harsh and maintenance is difficult. Therefore, higher quality and service performance requirements are imposed on wind power castings. As shown in the appendix Figure 1-2 is a large ductile iron wind power bearing seat (XB bearing seat). The casting product includes a casting body a. The casting body a includes a cylindrical-like structure a1. The cylindrical-like structure a1 has a hollow central hole a2. Vertical portions a3 are provided on both radial sides of the cylindrical-like structure a1. The overall blank weight of this casting is 4800 Kg, the pouring weight is 5700 Kg, the material is ductile iron EN-GJS-400-18LT, the external dimensions are 3585 mm × 2280 mm × 430 mm, the maximum wall thickness is 400 mm, and the minimum wall thickness is 60 mm. The two sides of the casting product are vertically extended key parts (vertical portions a3), and in the middle is a cylindrical-like structure with a central hole. This key part (vertical portion a3) is required to have no casting defects such as slag inclusions, shrinkage cavities, and shrinkage porosity, and the requirements are extremely high. In addition, a sampling rod is inserted into the 320-mm-thick key part (vertical portion a3) of the casting to test the mechanical properties (yield strength, tensile strength, elongation, impact performance, hardness) and metallography. The mechanical properties should meet the corresponding values in the EN 1563 standard for 60 mm < t (wall thickness) ≤ 200 mm. Its casting technology is very difficult, and conventional casting processes cannot achieve it.

[0003] This large ductile iron wind turbine bearing seat structure needs to use chillers and risers when designing the casting process. They are used to control the solidification process of the casting, so as to obtain dense castings without shrinkage cavities and shrinkage. Whether it is simultaneous solidification control technology or sequential solidification control technology, chillers are widely used. There are two types of chillers, internal chillers and external chillers, and external chillers are more widely used. External chillers are divided into direct chillers and indirect chillers; direct chillers are in direct contact with castings, requiring the surface of the chillers to be smooth, without oxide layers and oil stains, without pores or shrinkage, and during use, the surface of the chillers must be prevented from rusting. If the above requirements are not met, defects such as wrinkles and slag on the surface of the castings will occur; in addition, direct external chillers will absorb moisture when placed for a long time, resulting in pore defects on the surface of the castings. Therefore, direct chillers are usually used in the processing area of ​​the castings, because there is usually a processing allowance in the processing area of ​​the castings, and the external defects caused by the chillers can be removed during the processing of the castings, thereby obtaining qualified castings and improving the yield rate. In the non-machined areas of the casting, indirect chilling is required.

[0004] In the molding production process, process parameters such as the positioning of the indirect chiller and the distance between the casting and the indirect chiller directly affect the use effect of the chiller. In addition, the large indirect chiller is completely surrounded by the molding sand. The large indirect chiller must be securely fixed in the molding sand, otherwise, the casting mold is easily displaced or dropped during demolding, moving, and flipping, which directly affects the cooling effect of the chiller and even causes major safety accidents.

[0005] Sand cores are relatively common components in the casting field. The structure, size and positioning of sand cores vary according to actual needs. In conventional sand core positioning structures, it is only necessary to simply form the sand core head in the mold and use it. However, for some castings with particularly high requirements, it is necessary to consider not using sand cores or the accuracy of sand core positioning to avoid product scrapping due to inaccurate positioning of sand cores resulting in inconsistent casting dimensions or sand cores rubbing and falling off during assembly. Utility Model Content

[0006] In view of the above-mentioned deficiencies in the prior art, the present application provides an indirect chiller structure for casting a large ductile iron wind turbine bearing seat which does not require an additional sand core and can ensure a stable fixed position and obtain a casting with accurate size.

[0007] In order to solve the above-mentioned technical problems, the technical solution adopted in this application is as follows: an indirect chiller structure for casting a large ductile iron wind turbine bearing seat, which structure includes a cylindrical chiller body, a plurality of vertically extending sand hanging grooves are arranged on the outer peripheral side wall of the cylindrical chiller body, a gap is arranged between the cylindrical chiller body and the wind turbine bearing seat mold, and the gap is filled with molding sand; a tie rod is arranged on one axial end face of the cylindrical chiller body.

[0008] The above structure is used to pre-embed a cylindrical indirect chiller in the wind turbine bearing seat mold, and the two are arranged at equal intervals to form a circle of stable gap, and the gap is filled with molding sand, thereby determining the aperture size of the inner hole of the wind turbine bearing seat casting. Moreover, since the structure of the indirect chiller is a complete, integrated cylindrical indirect chiller, there is no need to additionally set up a sand core. Filling the radial inner and outer sides of the cylindrical indirect chiller with molding sand can not only serve as a sand core, but also have a cooling effect, killing two birds with one stone. In addition, the integrated cylindrical indirect chiller has fewer components and is easy to install and fix. In addition, the present application also provides a sand hanging groove on the outer peripheral wall of the cylindrical chiller body. The setting of this sand hanging groove can be used in the manufacturing process. When making a casting, the molding sand can flow downward along the sand hanging trough, which is also convenient for compacting the molding sand from top to bottom, thereby improving the adhesion of the sand layer to the large indirect chiller. The sand layer filled between the large indirect chiller and the mold can also be more tightly fixed to the large indirect chiller through the sand hanging trough, thereby solving the problem that the sand layer between the indirect chiller and the mold is easily separated. In addition, the present application also provides a tie rod on one end face of the indirect chiller. On the one hand, the tie rod is wrapped by the molding sand to make the large indirect chiller more firmly fixed in the casting. On the other hand, it is convenient for exhausting the large indirect chiller and the sand layer between the indirect chiller and the mold. The hot gas in the sand layer between the indirect chiller and the mold is discharged through the sand hanging trough to improve the cooling effect.

[0009] Furthermore, at least two tie bars are provided, and the two tie bars are arranged parallel to each other; by adopting the above structure, on the one hand, the tie bars can be wrapped by molding sand to make the large indirect chiller more firmly fixed in the mold, and on the other hand, the two tie bars can facilitate the transportation and lifting of the indirect chiller, and the installation process is smoother without tilting.

[0010] Furthermore, the distance between the two tie bars is 150-500mm, the inner diameter of the cylindrical indirect chiller is 1080mm, and the outer diameter is 1280mm; by adopting the above structure, the gap distance between the cylindrical indirect chiller and the mold can be effectively fixed, so that the indirect chiller can not only effectively realize the sand core function, but also have a good cooling effect on the casting.

[0011] Furthermore, the sand hanging grooves are evenly distributed along the circumference of the cylindrical cold iron body, and the length extension direction of the sand hanging grooves is parallel to the axial direction of the cylindrical cold iron body; with this structure, a plurality of sand hanging grooves can be evenly distributed around the circumference, so that during the filling process of molding sand, the molding sand can be evenly filled and compacted from all sides of the cold iron body, and the extension direction of the sand hanging grooves can provide sufficient guidance for the molding sand.

[0012] Furthermore, the width of the sand hanging groove is 15mm-25mm, and the depth is 3mm-10mm; the width of the tension bar is 50mm-80mm, and the height is 50mm-80mm.

[0013] Furthermore, the present application also provides a pulling and fixing system, which is connected to the tensioning bar, and the pulling and fixing system includes a hook connected to the tensioning bar, the upper end of the hook is connected to a pressure plate through a nut, and the lower surface of the pressure plate is fitted with a sand box block; the sand box block and the hook extend into the upper sand box, and the upper sand box is filled with molding sand, and the hook is tightened and pulled by the nut to pull the tensioning bar; using the above structure, a large indirect chiller is placed in the center hole of the wind turbine bearing seat mold, and the large indirect chiller is adjusted to The spacing between the wind turbine bearing seat molds, and then pour molding sand into the gap between the center hole of the mold and the indirect chiller and compact it. During the compaction process, the spacing between the large indirect chiller and the mold should be kept uniform and consistent. After completion, place the upper sand box, hook, pressure plate, nut and sand box stopper, and then fill the entire upper sand box cavity with molding sand. After the molding sand is completely hardened, tighten the nut. The above operation realizes the fixation of the large indirect chiller, which effectively prevents the sand layer in the gap between the large indirect chiller and the mold from falling off, damage, and displacement or falling of the large indirect chiller.

[0014] Furthermore, the sand box baffle is a grille-type structure, the pressure plate is overlapped on the upper surface of the grille, the pull hook passes through the grille, and the upper end extends to the upper surface of the sand box baffle, and the lower end is hooked with the tie rod; the above structure can improve the stability of the pull hook position, and can better connect and stabilize the indirect cold iron below during the process of screwing the nut.

[0015] Furthermore, the length extension direction of the sand box baffle is perpendicular to the length extension direction of the tie rod; the length of the pressing block is greater than the aperture of the grille hole; with this structure, when the pull hook is hooked to tighten the tie rod, force can be applied to the molding sand between the sand box baffle and the tie rod from two angles, and the pressing block is blocked by the grille to provide sufficient support for the pull hook during the pulling and tightening process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Structural schematic diagram of the first view of the wind turbine bearing seat casting of the present application.

[0017] Figure 2 Structural schematic diagram of the second view of the wind turbine bearing seat casting of the present application.

[0018] Figure 3 Structural schematic diagram of indirect chiller in the present application.

[0019] Figure 4 Structural schematic diagram of the indirect cold iron top view of the present application.

[0020] Figure 5 This application Figure 4 Structural schematic diagram of the local location of indirect cold iron.

[0021] Figure 6 This application Figure 4 Schematic diagram of the structure of the cross-sectional view of the indirect cold iron in the MM direction.

[0022] Figure 7 Schematic diagram of the structure of the indirect chiller and the drawing and fixing system combined in the present application.

[0023] Figure 8 This application Figure 7 A schematic diagram of the structure of a top view.

[0024] Fig. 9 This application Figure 8 Schematic diagram of the structure of the cross-sectional view in the QQ direction.

[0025] As shown in the attached figure: a. casting body, a1. cylindrical structure, a2. center hole, a3. vertical part, 1. cylindrical cold iron body, 101. sand hanging groove, 2. gap, 3. molding sand, 4. tie rod, 5. hook, 6. pressure plate, 7. sand box stopper, 8. upper sand box. DETAILED DESCRIPTION

[0026] The following will combine the embodiments and drawings to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only preferred embodiments, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention;

[0027] It should also be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be another intermediate component, fixed through the intermediate component. When a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be another intermediate component at the same time. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be another intermediate component at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by technicians in the technical field of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0028] The casting cavity of the present application can be the structure of the casting cavity for pouring, or the final casting structure, because the casting is obtained by first forming a cavity consistent with the casting structure, pouring molten iron in the cavity and cooling it. Therefore, the casting cavity (body) of the present application and the structure of the casting can be referred to as the same, and the structural relationship between each structure and the casting cavity body can also be seen as the structural relationship between the casting.

[0029] As attached Figure 3-6 As shown, an indirect chiller structure for casting a large ductile iron wind turbine bearing seat of the present application, the structure includes a cylindrical chiller body 1, a plurality of vertically extending sand hanging grooves 101 are arranged on the outer peripheral side wall of the cylindrical chiller body 1, a gap 2 is arranged between the cylindrical chiller body 1 and the wind turbine bearing seat mold, and the gap 2 is filled with molding sand 3; a tie rod 4 is arranged on one axial end face of the cylindrical chiller body 1.

[0030] The above structure is used to pre-embed a cylindrical indirect chiller in the wind turbine bearing seat mold, and the two are arranged at equal intervals to form a circle of stable gap, and the gap is filled with molding sand, thereby determining the aperture size of the inner hole of the wind turbine bearing seat casting. Moreover, since the structure of the indirect chiller is a complete, integrated cylindrical indirect chiller, there is no need to additionally set up a sand core. Filling the radial inner and outer sides of the cylindrical indirect chiller with molding sand can not only serve as a sand core, but also have a cooling effect, killing two birds with one stone. In addition, the integrated cylindrical indirect chiller has fewer components and is easy to install and fix. In addition, the present application also provides a sand hanging groove on the outer peripheral wall of the cylindrical chiller body. The setting of this sand hanging groove can be used in the manufacturing process. When making a casting, the molding sand can flow downward along the sand hanging trough, which is also convenient for compacting the molding sand from top to bottom, thereby improving the adhesion of the sand layer to the large indirect chiller. The sand layer filled between the large indirect chiller and the mold can also be more tightly fixed to the large indirect chiller through the sand hanging trough, thereby solving the problem that the sand layer between the indirect chiller and the mold is easily separated. In addition, the present application also provides a tie rod on one end face of the indirect chiller. On the one hand, the tie rod is wrapped by the molding sand to make the large indirect chiller more firmly fixed in the casting. On the other hand, it is convenient for exhausting the large indirect chiller and the sand layer between the indirect chiller and the mold. The hot gas in the sand layer between the indirect chiller and the mold is discharged through the sand hanging trough to improve the cooling effect.

[0031] As attached Figure 3-4As shown in 7-9, the tie bars 4 described in the present application are provided with at least two, and the two are arranged parallel to each other; the two tie bars can be fixed on one end face of the indirect chiller body by bonding, welding or other means, and the two ends of the extended length can protrude from the circumferential contour of the indirect chiller body to achieve overlapping; with the above structure, on the one hand, the tie bars can be wrapped by molding sand to make the large indirect chiller more firmly fixed in the mold, and on the other hand, the two tie bars can facilitate the transportation and lifting of the indirect chiller, and the installation process is smoother without tilting.

[0032] As an example, the distance between the two tie rods described in the present application is 150-500mm, the inner diameter of the cylindrical indirect chiller is 1080mm, and the outer diameter is 1280mm; by adopting the above structure, the gap distance between the cylindrical indirect chiller and the mold can be effectively fixed, so that the indirect chiller can not only effectively realize the sand core function, but also have a good cooling effect on the casting.

[0033] As attached Figure 3-4 As shown, the sand hanging grooves 101 described in the present application are evenly distributed along the circumference of the cylindrical cold iron body 1, and the length extension direction of the sand hanging grooves 101 is parallel to the axial direction of the cylindrical cold iron body 1 (the axial ends are flush); with this structure, a number of sand hanging grooves can be evenly distributed in the circumferential direction, so that the molding sand can be evenly filled and compacted from all sides of the cold iron body during the filling process, and the extension direction of the sand hanging grooves can provide sufficient guidance for the molding sand.

[0034] As an example, the sand hanging groove described in the present application has a width of 15mm to 25mm and a depth of 3mm to 10mm; the width of the tie rods described is 50mm to 80mm and a height of 50mm to 80mm.

[0035] More specifically, the width of the sand hanging groove is 20 mm and the depth is 5 mm; the width of the tie rod is 70 mm and the height is 50 mm to 70 mm (its cross section is a directional structure).

[0036] As attached Figure 7-9 As shown, the present application drawing and fixing system, the drawing and fixing system is connected to the said drawing bar 4, the said drawing and fixing system comprises a drawing hook 5 connected to the drawing bar 4, the upper end of the said drawing hook 5 is connected by a nut ( Figure 7-8As shown, it can be a conventional nut structure with an internal thread, which is threadedly connected to the external thread on the hook rod body) and is connected to a pressure plate 6, and the lower surface of the pressure plate 6 is fitted with a sand box block 7; the sand box block 7 and the hook 5 extend into the upper sand box 8, and the upper sand box 8 is filled with molding sand 3, and the hook 5 is tightened by the nut to pull the tension rod 4; specifically, the wind turbine bearing seat casting of the present application adopts a casting system that is a sand casting process in which the upper box body and the lower box body are snapped together, wherein the drawing and fixing system of the present application is pre-embedded in the upper box body, the indirect cold iron is also arranged in the upper box body, and a wind turbine bearing seat mold structure of the present application that is consistent with the structural shape of the wind turbine bearing seat casting is arranged between the upper and lower boxes, so that the casting cavity structure of the wind turbine bearing seat casting is formed in the molding sand of the upper and lower boxes, so as to facilitate the high-temperature molten iron to enter the mold cavity for cooling and finally form a casting; the above-mentioned sand casting process and mold, etc. of the present application are conventional settings of the casting process in this field; the most important innovation of the present application is that the cylindrical one-piece indirect The setting of the cold iron and the setting of the drawing and fixing system connected thereto; adopting the above structure, the large indirect cold iron is placed in the center hole (the center hole is the center hole of the same size structure of the wind turbine bearing seat casting) of the wind turbine bearing seat mold (the wind turbine bearing seat mold is placed in the lower sand box, not shown in the figure, and cooperates with the upper sand box, and the two are filled with molding sand to form a complete casting system structure of the casting), and the distance between the large indirect cold iron and the wind turbine bearing seat mold is adjusted. Then, the molding sand is poured into the gap between the center hole of the mold and the indirect cold iron and compacted. During the compacting process, the distance between the large indirect cold iron (that is, the indirect cold iron of the present application) and the mold should be kept uniform and consistent. After completion, the upper sand box, hook, pressure plate, nut and sand box block are placed, and then the entire upper sand box cavity is filled with molding sand. After the molding sand is completely hardened, the nut is tightened. The fixation of the large indirect cold iron is achieved through the above operation, and the sand layer in the gap between the large indirect cold iron and the mold is effectively prevented from falling off, damage, and displacement or falling of the large indirect cold iron.

[0037] As attached Figure 7-9 As shown, the sand box baffle 7 described in the present application is a grille structure (i.e., a plate-frame structure with multiple hollow holes), the pressure plate 6 is overlapped on the upper surface of the grille, the hook 5 passes through the grille, and the upper end extends to the upper surface of the sand box baffle 7, and the lower end is hooked with the tie rod 4; the grille-type sand box baffle of the present application is centrally arranged relative to the indirect chiller; the above structure can improve the stability of the position of the hook, and can better connect and stabilize the indirect chiller below during the process of screwing the nut; in addition, the sand box baffle is set, and the molding sand can be filled in the upper sand box from here, and it can also ensure that the hook is in the process of fastening and hooking the tie rod, giving the pressure plate sufficient support strength, thereby ensuring the position stability of the chiller body in the lower sand box body.

[0038] As attached Figure 8As shown, the length extension direction of the sand box baffle 7 described in the present application is perpendicular to the length extension direction of the tie rod 5; the length of the pressure block 6 is greater than the aperture of the grille hole; with this structure, when the pull hook is hooked to tighten the tie rod, force can be applied to the molding sand between the sand box baffle and the tie rod from two angles, and the pressure block is blocked by the grille to provide sufficient support for the pull hook during the pulling and tightening process.

[0039] In the above-mentioned scheme of the present application, the middle hole of the wind turbine bearing seat casting is no longer composed of traditional sand cores, but is made directly on the mold, which reduces the lifting of the sand core, the core lowering process and the grinding of the residual core head gap seam on the casting, thereby improving production efficiency; as an example, in the present application, in order to ensure the quality of the casting, a large indirect chiller is designed in the middle hole of the bearing seat, with an outer dimension of φ1280mm (external) × φ1080mm (inner) × 500mm (axial height) and a weight of 1.45 tons; when making the casting mold, the large indirect chiller is placed first, the thickness of the sand layer between the large indirect chiller and the mold is kept consistent, the sand layer is adhered to the large indirect chiller without detachment or falling off, and the large indirect chiller is fixed in the molding sand, which directly affects the cooling effect and safety of the chiller, and affects the casting temperature field and the supply of molten iron in the riser; the present application designs an indirect chiller structure with a cylindrical structure, and designs a plurality of sand hanging grooves on the circumferential outer side of the indirect chiller, and a plurality of sand hanging grooves on the axial Tie bars are arranged on the end surface, and the size specifications of the sand hanging groove can be 15mm-25mm in width and 3mm-10mm in depth, and the size specifications of the tie bars can be 50mm-80mm in width and 50mm-80mm in height; when making the casting mold, the molding sand can flow downward along the sand hanging groove, which is also convenient for the molding sand to be compacted from top to bottom, and the adhesion of the sand layer to the large indirect chiller is improved; the large indirect chiller and the sand layer of the mold are more tightly fixed on the large indirect chiller through the sand hanging groove (the setting of the sand hanging groove increases the contact area between the molding sand and the integrated cylindrical indirect chiller), which solves the problem that the sand layer between the indirect chiller and the mold is easily separated; the above-mentioned structure of the present application, on the one hand, wraps the tie bars by molding sand, so that the large indirect chiller is more firmly fixed in the casting mold, and on the other hand, it is convenient for the large indirect chiller and the sand layer between the indirect chiller and the mold to exhaust, and the hot gas of the sand layer between the indirect chiller and the mold is discharged through the sand hanging groove, thereby improving the cooling effect.

[0040] The specific operation process of the present application can be to place the large indirect chiller into the center hole of the mold, adjust the distance between the large indirect chiller and the mold, then place the molding sand in the gap and compact it. During the compacting process, the distance between the large indirect chiller and the mold should be kept uniform and consistent. After completion, place the upper sand box, hook, pressure plate, nut, etc., and then fill the entire upper sand box cavity with molding sand. After the molding sand is completely hardened, tighten the nut. The above operation realizes the fixation of the large indirect chiller, effectively preventing the sand layer between the large indirect chiller and the mold from falling off, damage, and displacement or falling of the large indirect chiller.

Claims

1. An indirect chiller for a wind turbine bearing seat, characterized in that: Its structure includes a cylindrical cold iron body, a plurality of vertically extending sand hanging grooves are arranged on the outer peripheral side wall of the cylindrical cold iron body, a gap is arranged between the cylindrical cold iron body and the wind turbine bearing seat mold, and the gap is filled with molding sand; and a tensioning rod is arranged on an axial end face of the cylindrical cold iron body.

2. The indirect chiller of the wind turbine bearing seat according to claim 1, characterized in that: At least two tensioning bars are provided, and the two tensioning bars are arranged parallel to each other.

3. The indirect chiller of the wind turbine bearing seat according to claim 1, characterized in that: The distance between the two tie bars is 150-500 mm, and the inner diameter of the cylindrical cold iron body is 1080 mm and the outer diameter is 1280 mm.

4. The indirect chiller of a wind turbine bearing seat according to claim 1, characterized in that: The sand hanging grooves are evenly distributed along the circumference of the cylindrical cold iron body, and the length extension direction of the sand hanging grooves is parallel to the axial direction of the cylindrical cold iron body.

5. The indirect chiller of the wind turbine bearing seat according to claim 4, characterized in that: The width of the sand hanging groove is 15mm-25mm, and the depth is 3mm-10mm; the width of the tension bar is 50mm-80mm, and the height is 50mm-80mm.

6. An indirect chiller drawing and fixing system for a wind turbine bearing seat according to claim 1, characterized in that: The pulling and fixing system is connected to the tensioning rod, and the pulling and fixing system includes a pulling hook connected to the tensioning rod, the upper end of the pulling hook is connected to a pressure plate through a nut, and the lower surface of the pressure plate is fitted with a sand box block; the sand box block and the pulling hook extend into the upper sand box, and the upper sand box is filled with molding sand, and the pulling hook is tightened and pulled by the tensioning rod through the nut.

7. The pulling and fixing system according to claim 6, characterized in that: The sand box baffle is a grille structure, the pressure plate is overlapped on the upper surface of the grille, the draw hook passes through the grille, and the upper end extends to the upper surface of the sand box baffle and the lower end is hooked with the draw bar.

8. The pulling and fixing system according to claim 7, characterized in that: The length extension direction of the sand box baffle is perpendicular to the length extension direction of the tension bar; the length of the pressing plate is greater than the aperture of the grille hole.

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