Sand core fixing device of complex thin-wall casting for nuclear power
By using a screw and core head fixing structure to mechanically lock the sand core, the problems of sand core displacement and collapse during the casting process are solved, improving the yield and sealing performance of castings. This method is suitable for casting complex thin-walled castings for nuclear power.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-21
- Publication Date
- 2026-04-07
AI Technical Summary
When casting complex thin-walled castings such as turbocharger supports for nuclear power plants, it is difficult to fix the sand core, which leads to the core support melting or softening, sand core displacement and collapse, affecting sealing and casting yield.
The design employs a screw fixing structure and a core head fixing structure, including a T-shaped screw and an anti-rotation right-hand double-ended nut, to mechanically lock the sand core, reducing the use of core supports and optimizing the exhaust channel design.
It improves the yield and sealing performance of castings, reduces the displacement and collapse problems caused by core support melting, ensures the dimensional accuracy and stability of castings, and reduces casting defects.
Smart Images
Figure CN224087908U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to foundry technology field, concretely relates to a sand core fixing device for complex thin-walled castings of nuclear power, and is especially suitable for the castings with complex inner cavity structure and high sealing requirement such as supercharger support. BACKGROUND
[0002] The supercharger support of nuclear power is a thin-walled casting with complex structure, high dimensional accuracy and casting quality requirement. Figures 6-8 As shown in the supercharger support casting, it is a complex shell composed of a plane and 12 cavities, and has working pressure and fluid temperature requirements.
[0003] From the structural characteristics and technical requirements of the supercharger support, the main casting difficulties are: the inner cavity is composed of multiple sealed chambers, and it is difficult to fix the sand core during casting. Figures 6-8 As shown in the figure, there are many sand cores 1', and the corresponding number of core supports 2' is also large. Defects: 1. The core support is easy to melt or soften at high temperature, causing the sand core to shift and collapse, resulting in casting defects; 2. Poor fusion between the core support and the casting body, affecting the sealing test and easily causing reliability problems such as water and oil leakage; 3. Difficult to exhaust the sand core and cavity, prone to casting defects such as gas retention and choking fire. Therefore, a new sand core fixing device is needed to solve the above problems. UTILITY MODEL CONTENTS
[0004] The utility model solves the technical problem: provide a kind of sand core fixing device for complex thin-walled castings of nuclear power, the utility model aims to reduce the use of core support by optimizing sand core fixing mode, solve the problems of sand core shift, collapse and difficult exhaust, improve the yield of casting and sealing performance.
[0005] To achieve the above purpose, the utility model adopts the technical scheme:
[0006] The sand core fixing device for complex thin-walled castings of nuclear power includes two kinds of sand core fixing structures, namely screw fixing structure and design process hole core head fixing structure.
[0007] The screw fixing structure includes a T-shaped screw, and the T-shaped embedded end of the T-shaped screw is embedded in the sand mold.
[0008] The core head fixing structure includes a core head, one end of which is assembled in the sand mold, and the other end is connected with the sand core to be fixed.
[0009] Further to the above scheme, the T-shaped screw includes a pre-buried end and a locking end, the pre-buried end of the T-shaped screw is a split designed T-shaped pre-buried structure, the T-shaped pre-buried structure is pre-buried in a sand mold after being sleeved with an anti-rotation right-handed double-headed nut; the locking end of the T-shaped screw is used for gap cooperation with a locking screw hole reserved on a sand core, one end of the locking screw hole is provided with a sand filling groove, when the sand core is assembled, the T-shaped screw is inserted into the anti-rotation right-handed double-headed nut through the sand core, and the other end is fixed in the sand filling groove through the locking nut and the gasket, and the sand filling groove is filled with sand to be flat.
[0010] Further to the above scheme, the threads at both ends of the inner hole of the anti-rotation right-handed double-headed nut are right-handed design and interrupted in the middle, and the outer shape of the anti-rotation right-handed double-headed nut is a partial circular structure; the anti-rotation right-handed double-headed nut is made of ordinary cast iron material.
[0011] Further to the above scheme, the length of the pre-buried end of the T-shaped screw is greater than 150 mm, and the length of the locking end is determined according to the thickness of the sand core and the size of the locking nut.
[0012] Further to the above scheme, the gap for cooperation between the T-shaped screw and the locking screw hole reserved on the sand core is 1-3 mm.
[0013] Further to the above scheme, the diameter of the T-shaped screw is determined by calculating the floating force of the sand core, and the safety factor is 2-3 times.
[0014] Further to the above scheme, the T-shaped screw is made of an ordinary hot-rolled steel bar.
[0015] Further to the above scheme, the core head is made of a material same as that of the casting, so that the core head is not softened.
[0016] Further to the above scheme, the core head adopts a conical steel bar and a cylindrical core head structure, one end of the core head is assembled in a sand mold, and the other end of the core head cooperates with a sand core support; the diameter of the conical steel bar is smaller than that of a positioning hole on the sand mold, and the cooperation gap is 0.5-1 mm.
[0017] Compared with the prior art, the utility model has the advantages of:
[0018] 1. The screw fixing structure composed of the T-shaped screw, the anti-rotation right-handed double-headed nut and the locking nut and the core head fixing structure made of the core head or the steel bar are adopted, so that the mechanical fixing of the sand core is realized, the use amount of the core support is reduced, and the size precision of the casting is ensured.
[0019] 2. The sand core fixing structure reduces the use amount of the core support, and only 2-4 core supports are needed to realize the sand core fixing structure, so that the problems of the sand core deviation and collapse caused by the melting of the core support are avoided.
[0020] 3、The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings.
[0021] 4、The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings.
[0022] 5、The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings. Figure 1 ;
[0024] Figure 2 The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings. Figure 2 ;
[0025] Figure 3 The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings. Figure 3 ;
[0026] Figure 4 The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings.
[0027] Figure 5 The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings.
[0028] Figure 6 The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings. Figure 1 ;
[0029] Figure 7 The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings. Figure 2 ;
[0030] Figure 8 The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings. Figure 3 . DETAILED DESCRIPTION
[0031] The sand core fixing device of the present application can improve the positioning accuracy and the dimensional stability of the castings.
[0032] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0033] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0034] Please see Figures 1-8 The embodiments of this utility model are described in detail below.
[0035] Example: Sand core fixing device for complex thin-walled castings for nuclear power plants, see reference. Figures 1-3 As shown, it includes two types of sand core fixing structures, namely a screw fixing structure and a core head fixing structure;
[0036] The screw fixing structure includes a T-shaped screw 3, the T-shaped pre-embedded end of the T-shaped screw 3 is pre-embedded in the sand mold 8, and the locking end of the T-shaped screw 3 passes through the sand core 9 to fix it;
[0037] The core head fixing structure includes a core head 7, one end of which is pre-embedded in the sand mold 8, and the other end of which is connected to the sand core 9 that needs to be fixed.
[0038] Example 2: The T-shaped screw 3 includes a pre-embedded end and a locking end. The pre-embedded end of the T-shaped screw 3 is a split-design T-shaped pre-embedded structure 11. The anti-rotation right-hand double-headed nut 2 is screwed onto the T-shaped pre-embedded structure 11 and then pre-embedded together in the sand mold 8. The locking end of the T-shaped screw 3 is used to fit with the locking screw hole reserved on the sand core 9. One end of the locking screw hole is provided with a sand filling groove. When assembling the sand core, the T-shaped screw 3 is passed through the sand core 9 and one end is installed and inserted into the anti-rotation right-hand double-headed nut 2. The other end is fixed in the sand filling groove by the locking nut 5 and the washer 4. The sand filling groove is filled with sand 6.
[0039] Preferred options, please refer to Figure 4 and 5As shown, the threads at both ends of the inner hole of the anti-rotation right-hand double-ended nut 2 are designed to be right-handed and broken in the middle. The shape of the anti-rotation right-hand double-ended nut 2 is a partially tangent circle structure to prevent self-rotation during locking and excessive tightening. The anti-rotation right-hand double-ended nut 2 is made of ordinary cast iron material, and its size can be selected according to the size of the sand core and buoyancy.
[0040] Preferably, the length of the pre-embedded end of the T-shaped screw 3 is determined according to the amount of sand it can absorb, and the maximum amount of sand it can absorb should be taken, at least greater than 150mm, to prevent the screw from falling off during the locking process; the length of the locking end is determined according to the thickness of the sand core and the size of the locking nut.
[0041] Preferably, the clearance between the T-shaped screw 3 and the pre-drilled locking screw hole on the sand core 9 is 1-3mm. The clearance is selected based on the size of the sand core; the larger the sand core, the larger the clearance.
[0042] Preferably, the diameter of the T-shaped screw 3 is calculated based on the tensile strength of the selected screw material and the buoyancy of the molten iron on the sand core. It is required that the sum of the tensile forces that all screws can withstand is at least 2-3 times the buoyancy of the sand core, with a safety factor of 2-3 times. The safety factor is selected according to the principle that the larger the volume of the sand core, the larger the safety factor.
[0043] Preferably, the T-shaped screw 3 is made of ordinary hot-rolled steel bar.
[0044] Example 3: The core head 7 is made of the same material as the casting, which facilitates fusion and prevents softening. The core head 7 may employ a structure of a tapered steel rod 1 and a cylindrical core head 12 as needed. One end of the core head 7 is fitted into the sand mold 8, and the other end of the core head 7 is supported and fitted with the sand core 9. The diameter of the tapered steel rod 1 is smaller than the diameter of the positioning hole on the sand mold 8, and the fitting clearance is 0.5-1mm.
[0045] This implementation also addresses the problem of difficult venting in castings. Because the large flat surface faces upwards and has almost no through holes connecting to the outside, gas in the mold cavity is difficult to escape. Furthermore, the complex internal sand core lacks venting channels, making venting even more difficult. The venting structure has been improved by pre-embedding venting channels in the sand core and outer mold, which can prevent gas from accumulating in the casting.
[0046] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0047] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A sand core fixing device for complex thin-walled castings used in nuclear power plants, characterized in that: It includes two types of sand core fixing structures, namely a screw fixing structure and a core head fixing structure; The screw fixing structure includes a T-shaped screw (3), the T-shaped pre-embedded end of the T-shaped screw (3) is pre-embedded in the sand mold (8), and the locking end of the T-shaped screw (3) passes through the sand core (9) to fix it; The core head fixing structure includes a core head (7), one end of which is embedded in the sand mold (8), and the other end of which is connected to the sand core (9) to be fixed.
2. The sand core fixing device for complex thin-walled castings for nuclear power plants according to claim 1, characterized in that: The T-shaped screw (3) includes a pre-embedded end and a locking end. The pre-embedded end of the T-shaped screw (3) is a split T-shaped pre-embedded structure (11). The anti-rotation right-hand double-headed nut (2) is screwed onto the T-shaped pre-embedded structure (11) and then pre-embedded together in the sand mold (8) for shaping. The locking end of the T-shaped screw (3) is used to fit with the locking screw hole reserved on the sand core (9). One end of the locking screw hole is provided with a sand filling groove. When assembling the sand core, the T-shaped screw (3) is passed through the sand core (9) and one end is installed and inserted into the anti-rotation right-hand double-headed nut (2). The other end is fixed in the sand filling groove by the locking nut (5) and the washer (4). The sand filling groove is filled with sand (6).
3. The sand core fixing device for complex thin-walled castings for nuclear power plants according to claim 2, characterized in that: The anti-rotation right-hand double-ended nut (2) has right-hand threads at both ends of its inner hole and is broken in the middle. The anti-rotation right-hand double-ended nut (2) has a partially tangent circle structure. The anti-rotation right-hand double-ended nut (2) is made of ordinary cast iron material.
4. The sand core fixing device for complex thin-walled castings for nuclear power plants according to claim 2, characterized in that: The pre-embedded end length of the T-shaped screw (3) is greater than 150mm, and the locking end length is determined according to the sand core thickness and the locking nut size.
5. The sand core fixing device for complex thin-walled castings for nuclear power plants according to claim 2, characterized in that: The clearance between the T-shaped screw (3) and the locking screw hole reserved on the sand core (9) is 1-3mm.
6. The sand core fixing device for complex thin-walled castings for nuclear power plants according to claim 2, characterized in that: The diameter of the T-shaped screw (3) is determined by calculating the buoyancy of the sand core, with a safety factor of 2-3 times.
7. The sand core fixing device for complex thin-walled castings for nuclear power plants according to claim 2, characterized in that: The T-shaped screw (3) is made of ordinary hot-rolled steel bar.
8. The sand core fixing device for complex thin-walled castings for nuclear power plants according to claim 1, characterized in that: The core (7) is made of the same material as the casting, which facilitates fusion and prevents softening.
9. The sand core fixing device for complex thin-walled castings for nuclear power plants according to claim 1, characterized in that: The core head (7) is made of a tapered steel rod (1) and a cylindrical core head (12). One end of the core head (7) is assembled in the sand mold (8), and the other end of the core head (7) is supported and fitted with the sand core (9). The diameter of the tapered steel rod (1) is smaller than the diameter of the positioning hole on the sand mold (8), and the fitting gap is 0.5-1mm.