Long-size sand core mold with anti-shrinkage structure and sand cake forming method

Abstract

The invention discloses a long-size sand core mold with an anti-shrinkage structure and a sand cake forming method. The sand core mold comprises a winding core shaft, wherein a plurality of I-shaped sand cakes with cylindrical cavities are sequentially arranged on the winding core shaft in a sleeving manner; the axial section of the I-shaped sand cake is an I-shaped cavity, a shaft sleeve is pre-buried in the middle of the I-shaped cavity, sand consolidation grooves are formed in the peripheral face of the shaft sleeve at intervals and filled with sand materials, and first threaded holes are formed in the bottom end face of the shaft sleeve in the circumferential direction; two half expansion sleeves which are symmetrically arranged are arranged in the shaft sleeve in a sleeved mode, each half expansion sleeve is clamped on the periphery of the winding mandrel, the bottom end of each half expansion sleeve extends in the radial direction to form a flange, and each flange extends to the outer side of the shaft sleeve embedded in the inner periphery of the I-shaped sand cake. And through holes in one-to-one correspondence with the first threaded holes are formed in each flange. The axial shrinkage problem caused by the fact that the sand core mold is pressed is avoided, the core mold forming structure is reliable, and the heat insulation forming quality in an engine is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of rocket engine shell molding and manufacturing, and in particular to a long-size sand core mold with an anti-shrinkage structure and a sand cake molding method. Background Art

[0002] Solid rocket fiber winding engines with large aspect ratio have the characteristics of high thrust, strong adaptability, light weight, high strength, high rigidity, etc. The winding core molds are often made of sand core molds with advantages such as high strength, water solubility, easy processing and fast molding.

[0003] However, as the engine length increases, the difficulty of assembling the sand core mold increases, and the large aspect ratio sand core mold has problems such as barrel section joint cracks and axial size shrinkage during the molding process, which directly affects the insulation molding quality and external dimensions of the shell. These problems have always been the bottleneck for achieving high-quality and efficient molding of the shell.

[0004] The Chinese patent (CN112405959A) designs a lightweight sand core mold by reducing the weight of the sand cake, but the core mold is small in size and short in length, and does not take into account the assembly of large-size sand core molds and the axial shrinkage caused by the pressure on the sand core mold, making it difficult to adapt to a shell with a large aspect ratio. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention proposes a long-size sand core mold with an anti-shrinkage structure and a sand cake forming method, which takes into account the assembly of large-size sand core molds and the axial shrinkage problem caused by the pressure on the sand core molds, and meets the use of sand core molds with a large aspect ratio for winding shells.

[0006] To achieve the above object, the present invention designs a long-size sand core mold with an anti-shrinkage structure, including a winding mandrel, which is special in that: a plurality of hollow cylindrical I-shaped sand cakes are sequentially sleeved on the winding mandrel, and the bonding surfaces of adjacent I-shaped sand cakes are in a bonding state;

[0007] The axial section of the I-shaped sand cake is an I-shaped cavity, and a shaft sleeve is pre-buried in the middle of the I-shaped cavity, and the outer peripheral surface of the shaft sleeve is provided with sand consolidation grooves arranged at intervals, and the sand consolidation grooves are filled with mortar mixture, and the bottom end surface of the shaft sleeve is flush with the bottom diameter-changing end surface of the I-shaped, and the bottom end surface of the shaft sleeve is provided with a circumferentially arranged first threaded hole, and the axial direction of the first threaded hole is parallel to the axial direction of the shaft sleeve;

[0008] The shaft sleeve is internally sleeved with two half-type expansion sleeves arranged symmetrically, each half of the expansion sleeve is clamped on the outer circumference of the winding mandrel, and the bottom end of each half of the expansion sleeve is radially extended with a flange, each flange extends to the outer side of the shaft sleeve pre-embedded on the inner circumference of the I-shaped sand cake, and each flange is provided with a through hole corresponding to the first threaded hole one by one, and the through hole is connected and fixed to the first threaded hole by a screw, so that the I-shaped sand cake is fixed on the winding mandrel;

[0009] A second threaded hole is also arranged between adjacent through holes. When the I-shaped sand cake is dissolved, the expansion sleeve is separated from the shaft sleeve by pushing the second threaded hole with a screw.

[0010] Furthermore, a flat washer and a spring washer are provided between the screw and the through hole to prevent loosening.

[0011] Furthermore, the front end sleeve of the winding mandrel is provided with a front head sand cake that matches the front end of the sand core mold, and the front head sand cake is bonded to the adjacent I-shaped sand cake; the axial section of the front head sand cake is an I-shaped cavity, and a shaft sleeve is pre-embedded in the I-shaped cavity, and the outer peripheral surface of the shaft sleeve is provided with spaced sand consolidation grooves, the sand consolidation grooves are filled with sand, the bottom end face of the shaft sleeve is flush with the bottom end face of the I-shape, and the bottom end face of the shaft sleeve is provided with circumferentially arranged first threaded holes, and the axial direction of the first threaded holes is parallel to the axial direction of the shaft sleeve.

[0012] Furthermore, the rear end sleeve of the winding mandrel is provided with a rear head sand cake that matches the rear end of the sand core mold, and the rear head sand cake is bonded to the adjacent I-shaped sand cake; the axial section of the rear head sand cake is an I-shaped cavity, and a shaft sleeve is pre-embedded in the I-shaped cavity, and the outer peripheral surface of the shaft sleeve is provided with spaced sand consolidation grooves, the sand consolidation grooves are filled with sand, the bottom end face of the shaft sleeve is flush with the bottom end face of the I-shaped cavity, and the bottom end of the shaft sleeve is fixed by a locking nut.

[0013] The present invention also provides a sand cake forming method for a long-size sand core mold with an anti-shrinkage structure, which is applicable to the above-mentioned long-size sand core mold with an anti-shrinkage structure, and the method is particularly characterized in that it comprises the following steps:

[0014] S1) making a sand cake forming mold according to the structural dimensions of the sand core mold;

[0015] S2) using a sand cake forming mold to make an I-shaped sand cake;

[0016] S3) processing and manufacturing the front end sand cake and the rear end sand cake according to the structural dimensions of the sand core mold;

[0017] S4) Install the front head sand cake, insert the expansion sleeve into the shaft sleeve of the front head sand cake, insert the spring washer and the flat washer on the screw in sequence, pass through the through hole and the first threaded hole, and fix the front head sand cake on the mandrel;

[0018] S5) installing an I-shaped sand cake adjacent to the front end sand cake according to step S4), and applying adhesive on the butt joint surfaces of the front end sand cake and the adjacent I-shaped sand cake, so that the I-shaped sand cake is closely attached to the front end sand cake and limited in position;

[0019] S6) according to step S4), the following I-shaped sand cakes are sequentially installed on the winding mandrel, and the adjacent I-shaped sand cakes are respectively coated with adhesive to closely fit and limit the adjacent I-shaped sand cakes;

[0020] S7) Apply adhesive to the butt joint surfaces of the last I-shaped sand cake and the rear end sand cake respectively, and then in step S4) install the rear end sand cake on the winding mandrel, and fix the rear end sand cake with a locking nut;

[0021] S8) After curing at room temperature for a period of time, the assembled sand core mold is machined according to the requirements of the product inner surface.

[0022] Further, in S1), the sand cake forming mold includes a cylindrical shell with a sealed bottom end and an open top end, a convex lower weight-reducing ring is placed at the bottom end of the cylindrical shell, a positioning sleeve with a π-shaped longitudinal section is inserted at the convex top end of the lower weight-reducing ring, a shaft sleeve is arranged around the positioning sleeve, and a concave upper weight-reducing ring is clamped between the positioning sleeve and the shaft sleeve.

[0023] Furthermore, in S2), the specific steps of making the I-shaped sand cake are as follows:

[0024] S21) connecting the lower weight-reducing ring and the positioning sleeve to the central position of the bottom end of the cylindrical housing with a draft angle of 1°;

[0025] S22) Then, a silicone rubber release agent is applied to the surface of the assembled mold, and then the sleeve is installed on the positioning sleeve, and the mortar mixture is poured into the cavity formed by the lower weight-reducing ring, the sleeve and the cylindrical shell in batches, and the mortar mixture is tamped;

[0026] S23) When the mortar mixture is filled to the upper end surface of the shaft sleeve, the upper weight-reducing ring is placed along the positioning sleeve, and the mortar mixture is continued to be added and tamped to the upper end surface of the upper weight-reducing ring;

[0027] S24) finally solidifies and demoulds to obtain an I-shaped sand cake.

[0028] Furthermore, before step S4), the end faces of the I-shaped sand cake, the front end sand cake, and the rear end sand cake are respectively milled to ensure the total height of a single sand cake.

[0029] Furthermore, in S5), S6), and S7), the butt joint surfaces of the front head sand cake, the I-shaped sand cake, and the rear head sand cake are respectively coated with CH-31 epoxy adhesive.

[0030] The advantages of the present invention are:

[0031] 1. The sand cake forming mold designed by the present invention can be quickly assembled and disassembled, and is convenient for demoulding the sand cake;

[0032] 2. The outer periphery of the shaft sleeve of the present invention is designed with a sand consolidation groove to effectively prevent the sand cake from separating from the shaft sleeve and prevent the sand core mold from radial collapse and axial contraction;

[0033] 3. The butt joints between adjacent sand cakes in the present invention are bonded with adhesive, which can effectively prevent the butt joints between the sand cakes from cracking due to the deflection of the sand core mold;

[0034] 4. During the installation of the sand core mold, the connecting screws between the expansion sleeve and the shaft sleeve use spring washers + flat washers to prevent the expansion sleeve and the shaft sleeve from loosening and disengaging during vibration and heating;

[0035] 5. After the sand core mold water is dissolved, the expansion sleeve and the shaft sleeve are disassembled by connecting screws, which is convenient and quick and can be reused;

[0036] The invention discloses a long-sized sand core mold with an anti-shrinkage structure and a sand cake forming method, wherein an expansion sleeve and a shaft sleeve are used to assemble the large-sized sand core mold, thereby avoiding the axial shrinkage problem caused by the sand core mold being compressed. The core mold forming structure is reliable, and the insulation forming quality in the engine is ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the three-dimensional structure of the sand core mold in the present invention;

[0038] Figure 2 It is an axial cross-sectional view of the sand cake sleeve of the present invention being arranged on the winding mandrel;

[0039] Figure 3 for Figure 2 A partial enlarged view of the

[0040] Figure 4 It is a schematic diagram of the three-dimensional structure of the shaft sleeve in the present invention;

[0041] Figure 5 It is a schematic diagram of the three-dimensional structure of the expansion sleeve in the present invention;

[0042] Figure 6 It is a schematic diagram of the three-dimensional structure in which the expansion sleeve and the shaft sleeve are installed together in the present invention;

[0043] Figure 7 It is an axial cross-sectional view of the sand cake forming mold in the present invention;

[0044] In the figure: winding mandrel 1, I-shaped sand cake 2, shaft sleeve 3, expansion sleeve 4, locking nut 5, front head sand cake 6, rear head sand cake 7, sand cake forming mold 8;

[0045] The shaft sleeve 3 includes: a sand consolidation groove 3-1 and a first threaded hole 3-2;

[0046] The expansion sleeve 4 includes: a flange 4-1, a through hole 4-2, a flat gasket 4-3, a spring gasket 4-4, a screw 4-5, and a second threaded hole 4-6;

[0047] The sand cake forming mold 8 includes: a cylindrical shell 8-1, a lower weight-reducing ring 8-2, a positioning sleeve 8-3, and an upper weight-reducing ring 8-4. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0049] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0050] like Figures 1 to 6 As shown, the long-sized sand core mold with an anti-shrinkage structure of the present invention comprises a winding mandrel 1, on which a plurality of hollow cylindrical I-shaped sand cakes 2 are sequentially sleeved, and the bonding surfaces of adjacent I-shaped sand cakes 2 are in a bonding state.

[0051] The butt joints between adjacent sand cakes are bonded with adhesive, which can effectively prevent the butt joints between the sand cakes from cracking due to the deflection of the sand core mold.

[0052] The axial section of the I-shaped sand cake 2 is an I-shaped cavity, and a sleeve 3 is pre-buried in the middle of the I-shaped cavity. The outer peripheral surface of the sleeve 3 is provided with spaced sand consolidation grooves 3-1, and the sand consolidation grooves 3-1 are filled with mortar mixture. The bottom end surface of the sleeve 3 is flush with the bottom diameter reducing end surface of the I-shape, and the bottom end surface of the sleeve 3 is provided with a circumferentially arranged first threaded hole 3-2, and the axial direction of the first threaded hole 3-2 is parallel to the axial direction of the sleeve 3.

[0053] The I-shaped cavity of the I-shaped sand cake 2 is used to reduce the weight of the sand cake. A sleeve 3 is arranged in the middle of the cavity, and a sand consolidation groove 3-1 designed on the outer periphery of the sleeve 3 is used to prevent the sand cake from being separated from the sleeve 3 by force, and to prevent the sand core mold from radial collapse and axial contraction. The middle part of the winding mandrel 1 is designed with equal diameter to ensure the strength of the mandrel.

[0054] The shaft sleeve 3 is internally sleeved with two-half expansion sleeves 4 arranged symmetrically, each half of the expansion sleeve 4 is clamped on the outer circumference of the winding mandrel 1, and the bottom end of each half of the expansion sleeve 4 is radially extended with a flange 4-1, each of the flanges 4-1 extends to the outer side of the shaft sleeve 3 embedded in the inner circumference of the I-shaped sand cake 2, and each of the flanges 4-1 is provided with a through hole 4-2 corresponding to the first threaded hole 3-2, and the through hole 4-2 is connected and fixed to the first threaded hole 3-2 by a screw 4-5, so that the I-shaped sand cake 2 is fixed on the winding mandrel 1.

[0055] The expansion sleeve 4 adopts a two-half structure for easy disassembly and assembly.

[0056] Preferably, a flat washer 4-3 and a spring washer 4-4 are provided between the screw 4-5 and the through hole 4-2 to prevent loosening, so as to prevent the expansion sleeve 4 and the shaft sleeve 3 from loosening and disengaging during vibration and heating.

[0057] A second threaded hole 4-6 is further provided between adjacent through holes 4-2. When the I-shaped sand cake 2 is dissolved, the expansion sleeve 4 is separated from the shaft sleeve 3 by screwing the second threaded hole 4-6.

[0058] After the product is formed, the sand core mold is dissolved by water, and the sleeve 3, the expansion sleeve 4 and the winding mandrel 1 are taken out together. Then the expansion sleeve 4 is pushed back by the connecting screws to disassemble the expansion sleeve 4 and the sleeve 3. It is convenient and quick and can be reused.

[0059] Preferably, the front end sleeve of the winding mandrel 1 is provided with a front head sand cake 6 that matches the front end of the sand core mold, and the front head sand cake 6 is bonded to the adjacent I-shaped sand cake 2; the axial section of the front head sand cake 6 is an I-shaped cavity, and a sleeve 3 is pre-embedded in the I-shaped cavity, and the outer peripheral surface of the sleeve 3 is provided with spaced sand consolidation grooves 3-1, and the sand consolidation grooves 3-1 are filled with sand material, the bottom end face of the sleeve 3 is flush with the bottom end face of the I-shape, and the bottom end face of the sleeve 3 is provided with a circumferentially arranged first threaded hole 3-2, and the axial direction of the first threaded hole 3-2 is parallel to the axial direction of the sleeve 3.

[0060] Preferably, the rear end sleeve of the winding mandrel 1 is provided with a rear end sand cake 7 matching the rear end of the sand core mold, and the rear end sand cake 7 is bonded to the adjacent I-shaped sand cake 2; the axial section of the rear end sand cake 7 is an I-shaped cavity, and a shaft sleeve 3 is pre-embedded in the I-shaped cavity, and the outer peripheral surface of the shaft sleeve 3 is provided with spaced sand consolidation grooves 3-1, and the sand consolidation grooves 3-1 are filled with sand material, the bottom end face of the shaft sleeve 3 is flush with the bottom end face of the I-shaped cavity, and the bottom end of the shaft sleeve 3 is fixed by a locking nut 5.

[0061] The large aspect ratio sand core mold produced by the present invention has the characteristics of high strength, light weight and simple molding. It avoids the problem of product inner surface wrinkles caused by extrusion of the sand cake butt surface due to core mold shrinkage, the problem of product inner surface size changes, and the problem of winding product tension changes. It is suitable for the production of large aspect ratio shells.

[0062] The present invention also provides a sand cake forming method of a long-size sand core mold with an anti-shrinkage structure, which is applicable to the above-mentioned long-size sand core mold with an anti-shrinkage structure, and comprises the following steps:

[0063] S1) making a sand cake forming mold 8 according to the structural dimensions of the sand core mold.

[0064] Specifically, Figure 7 As shown, the sand cake forming mold 8 includes a cylindrical shell 8-1 with a sealed bottom end and an open top end, a convex lower weight-reducing ring 8-2 is placed at the bottom end of the cylindrical shell 8-1, a positioning sleeve 8-3 with a π-shaped longitudinal section is inserted at the convex top end of the lower weight-reducing ring 8-2, a shaft sleeve 3 is arranged around the positioning sleeve 8-3, and a concave upper weight-reducing ring 8-4 is clamped between the positioning sleeve 8-3 and the shaft sleeve 3.

[0065] The sand cake forming mold designed by the present invention is designed with 8 parts, which can be quickly assembled and disassembled, and is convenient for demoulding the sand cake.

[0066] S2) Use the sand cake forming mold 8 to make an I-shaped sand cake 2.

[0067] The specific steps of making I-shaped sand cake 2 are as follows:

[0068] S21) Connect the lower weight reducing ring 8-2 and the positioning sleeve 8-3 to the central position of the bottom end of the cylindrical shell 8-1 with a draft angle of 1°.

[0069] S22) Then, a silicone rubber release agent is applied to the surface of the assembled mold, and then the sleeve 3 is installed on the positioning sleeve 8-3, and the mortar mixture is poured into the cavity formed by the lower weight-reducing ring 8-2, the sleeve 3 and the cylindrical shell 8-1 in batches, and the mortar mixture is tamped.

[0070] In this embodiment, the mortar mixture is a water-soluble polyvinyl alcohol mortar mixture.

[0071] S23) When the mortar mixture is filled to the upper end surface of the shaft sleeve 3, the upper weight-reducing ring 8-4 is placed along the positioning sleeve 8-3, and the mortar mixture is continued to be added and tamped to the upper end surface of the upper weight-reducing ring 8-4.

[0072] S24) Finally, solidification and demoulding are performed to obtain an I-shaped sand cake 2.

[0073] S3) The front end sand cake 6 and the rear end sand cake 7 are manufactured according to the structural dimensions of the sand core mold.

[0074] The end faces of the I-shaped sand cake 2, the front end sand cake 6, and the rear end sand cake 7 are respectively milled to ensure the total height of a single sand cake.

[0075] S4) Install the front head sand cake 6, insert the expansion sleeve 4 into the shaft sleeve 3 of the front head sand cake 6, insert the spring washer 4-4 and the flat washer 4-3 on the screw 4-5 in sequence, pass through the through hole 4-2 and the first threaded hole 3-2 to fix the front head sand cake 6 on the core shaft 1.

[0076] S5) Install the I-shaped sand cake 2 adjacent to the front end sand cake 6 according to step S4), and apply adhesive on the joint surface of the front end sand cake 6 and the adjacent I-shaped sand cake 2, so that the I-shaped sand cake 2 and the front end sand cake 6 are tightly attached and limited.

[0077] S6) According to step S4), the following I-shaped sand cakes 2 are sequentially installed on the winding mandrel 1, and adhesive is scraped and applied to the butt joint surfaces of adjacent I-shaped sand cakes 2 respectively, so that the adjacent I-shaped sand cakes 2 are closely attached and limited.

[0078] The individual sand cakes in the present invention are connected by the expansion sleeve 4 and have a self-locking function, which effectively solves the problem of axial contraction of the sand core mold with a large aspect ratio and the problem of cracking and squeezing of the sand cake joints during the rotation and swinging of the core mold, resulting in insulation wrinkles in the product.

[0079] S7) The adhesive is scraped and coated on the butt surfaces of the last I-shaped sand cake 2 and the rear end sand cake 7, and then in step S4) the rear end sand cake 7 is installed on the winding mandrel 1, and the locking nut 5 is used to fix the rear end sand cake 7.

[0080] Preferably, in S5), S6), and S7), the butt joint surfaces of the front head sand cake 6, the I-shaped sand cake 2, and the rear head sand cake 7 are respectively coated with CH-31 epoxy adhesive.

[0081] S8) After curing at room temperature for a period of time, the assembled sand core mold is machined according to the requirements of the product inner surface.

[0082] Specifically, after curing at room temperature for 24 hours, the assembled sand core mold is machined according to the inner surface requirements of the product.

[0083] The long-size sand core mold with an anti-shrinkage structure in the present invention can be assembled horizontally or vertically, which is convenient for operation. The sand cake forming method in the present invention uses an expansion sleeve and a shaft sleeve to assemble a large-size sand core mold, thereby avoiding the axial shrinkage problem caused by the pressure on the sand core mold. The core mold forming structure is reliable, and the insulation forming quality in the engine is guaranteed.

[0084] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A long-size sand core mold with an anti-shrinkage structure, comprising a winding mandrel (1), characterized in that: A plurality of hollow cylindrical I-shaped sand cakes (2) are sequentially sleeved on the winding mandrel (1), and the bonding surfaces of adjacent I-shaped sand cakes (2) are in a bonding state; The I-shaped sand cake (2) has an I-shaped cavity in its axial section, and a shaft sleeve (3) is pre-buried in the middle of the I-shaped cavity; the outer peripheral surface of the shaft sleeve (3) is provided with sand consolidation grooves (3-1) arranged at intervals; the sand consolidation grooves (3-1) are filled with mortar mixture; the bottom end surface of the shaft sleeve (3) is flush with the bottom diameter-changing end surface of the I-shaped; the bottom end surface of the shaft sleeve (3) is provided with a circumferentially arranged first threaded hole (3-2), and the axial direction of the first threaded hole (3-2) is parallel to the axial direction of the shaft sleeve (3); The shaft sleeve (3) is internally sleeved with two half-type expansion sleeves (4) arranged symmetrically, each half of the expansion sleeve (4) is clamped on the outer circumference of the winding mandrel (1), and the bottom end of each half of the expansion sleeve (4) is provided with a flange (4-1) extending radially, each flange (4-1) extending to the outer side of the shaft sleeve (3) pre-buried on the inner circumference of the I-shaped sand cake (2), each flange (4-1) is provided with a through hole (4-2) corresponding to the first threaded hole (3-2), and the through hole (4-2) and the first threaded hole (3-2) are connected and fixed by a screw (4-5), so that the I-shaped sand cake (2) is fixed on the winding mandrel (1); A second threaded hole (4-6) is also provided between adjacent through holes (4-2). When the I-shaped sand cake (2) is dissolved, the expansion sleeve (4) is separated from the shaft sleeve (3) by screwing the second threaded hole (4-6).

2. The anti-shrinkage structure long-size sand core mold according to claim 1, characterized in that: A flat washer (4-3) and a spring washer (4-4) for preventing loosening are arranged between the screw (4-5) and the through hole (4-2).

3. The anti-shrinkage structure long-size sand core mold according to claim 2, characterized in that: The front end sleeve of the winding mandrel (1) is provided with a front end sealing sand cake (6) matching the front end of the sand core mold, and the front end sealing sand cake (6) is in a bonding state with the adjacent I-shaped sand cake (2); the axial section of the front end sealing sand cake (6) is an I-shaped cavity, and a shaft sleeve (3) is pre-buried in the I-shaped cavity; the outer peripheral surface of the shaft sleeve (3) is provided with spaced sand consolidation grooves (3-1), and the sand consolidation grooves (3-1) are filled with sand material; the bottom end surface of the shaft sleeve (3) is flush with the bottom end surface of the I-shaped cavity; the bottom end surface of the shaft sleeve (3) is provided with a circumferentially arranged first threaded hole (3-2), and the axial direction of the first threaded hole (3-2) is parallel to the axial direction of the shaft sleeve (3).

4. The anti-shrinkage structure long-size sand core mold according to claim 2, characterized in that: The rear end sleeve of the winding mandrel (1) is provided with a rear end sealing sand cake (7) matching the rear end of the sand core mold, and the rear end sealing sand cake (7) is in a bonding state with the adjacent I-shaped sand cake (2); the axial section of the rear end sealing sand cake (7) is an I-shaped cavity, and a shaft sleeve (3) is pre-buried in the I-shaped cavity, and the outer peripheral surface of the shaft sleeve (3) is cut with spaced sand consolidation grooves (3-1), and the sand consolidation grooves (3-1) are filled with sand material, the bottom end surface of the shaft sleeve (3) is flush with the bottom end surface of the I-shaped cavity, and the bottom end of the shaft sleeve (3) is fixed by a locking nut (5).

5. A sand cake forming method of a long-size sand core mold with an anti-shrinkage structure, suitable for the long-size sand core mold with an anti-shrinkage structure as claimed in any one of claims 1 to 4, characterized in that: The steps include: S1) making a sand cake forming mold (8) according to the structural dimensions of the sand core mold; S2) using a sand cake forming mold (8) to make an I-shaped sand cake (2); S3) processing and manufacturing a front end sand cake (6) and a rear end sand cake (7) according to the structural dimensions of the sand core mold; S4) installing the front end sand cake (6), inserting the expansion sleeve (4) into the shaft sleeve (3) of the front end sand cake (6), inserting the spring washer (4-4) and the flat washer (4-3) on the screw (4-5) in sequence, passing through the through hole (4-2) and the first threaded hole (3-2), and fixing the front end sand cake (6) on the mandrel (1); S5) installing the I-shaped sand cake (2) adjacent to the front end sand cake (6) according to step S4), and applying adhesive on the butt joint surfaces of the front end sand cake (6) and the adjacent I-shaped sand cake (2), so as to closely contact and limit the position of the I-shaped sand cake (2) and the front end sand cake (6); S6) according to step S4), sequentially installing the following I-shaped sand cakes (2) on the winding mandrel (1), and applying adhesive to the butt joint surfaces of adjacent I-shaped sand cakes (2) respectively, so that the adjacent I-shaped sand cakes (2) are closely attached and limited in position; S7) applying adhesive to the butt joint surfaces of the last I-shaped sand cake (2) and the rear end sand cake (7), and then installing the rear end sand cake (7) on the winding mandrel (1) in step S4), and fixing the rear end sand cake (7) with a locking nut (5); S8) After curing at room temperature for a period of time, the assembled sand core mold is machined according to the requirements of the product inner surface.

6. The sand cake forming method of the long-size sand core mold with an anti-shrinkage structure according to claim 5 is characterized in that: S1), the sand cake forming mold (8) comprises a cylindrical shell (8-1) with a sealed bottom end and an open top end, a convex lower weight-reducing ring (8-2) is placed at the bottom end of the cylindrical shell (8-1), a positioning sleeve (8-3) with a π-shaped longitudinal section is inserted at the convex top end of the lower weight-reducing ring (8-2), a shaft sleeve (3) is arranged around the positioning sleeve (8-3), and a concave upper weight-reducing ring (8-4) is clamped between the positioning sleeve (8-3) and the shaft sleeve (3).

7. The sand cake forming method of the long-size sand core mold with an anti-shrinkage structure according to claim 6 is characterized by: In S2), the specific steps of making the I-shaped sand cake (2) are as follows: S21) connecting the lower weight-reducing ring (8-2) and the positioning sleeve (8-3) to the central position of the bottom end of the cylindrical housing (8-1) with a draft angle of 1°; S22) Then, a silicone rubber release agent is applied to the surface of the assembled mold, and then the shaft sleeve (3) is installed on the positioning sleeve (8-3), and the mortar mixture is poured into the cavity formed by the lower weight-reducing ring (8-2), the shaft sleeve (3) and the cylindrical shell (8-1) in batches, and the mortar mixture is compacted; S23) when the mortar mixture is filled to the upper end surface of the shaft sleeve (3), the upper weight-reducing ring (8-4) is placed along the positioning sleeve (8-3), and the mortar mixture is continued to be added and tamped to the upper end surface of the upper weight-reducing ring (8-4); S24) Finally, solidification and demoulding are performed to obtain an I-shaped sand cake (2).

8. The sand cake forming method of the long-size sand core mold with an anti-shrinkage structure according to claim 7 is characterized in that: Before step S4), the end faces of the I-shaped sand cake (2), the front end sand cake (6), and the rear end sand cake (7) are respectively milled to ensure the total height of each sand cake.

9. The sand cake forming method of the long-size sand core mold with an anti-shrinkage structure according to claim 8, characterized in that: In S5), S6), and S7), the butt joint surfaces of the front end sand cake (6), the I-shaped sand cake (2), and the rear end sand cake (7) are respectively coated with CH-31 epoxy adhesive.

Images