Elongated hole casting sand core structure

Abstract

The utility model relates to casting technical field, and disclose the sand core structure for slender hole casting, including a plurality of process steel pipes, the bottom of process steel pipe is detachably connected with the external thread ring through bolt, the top of process steel pipe is equipped with the annular thread groove of cooperation and use with external thread ring, the bottom of process steel pipe is not equipped with annular thread groove in bottom, the top of process steel pipe top end is connected with the top steel pipe through the same external thread ring thread connection with its bottom, and top steel pipe is replaceable, and a plurality of process steel pipes and top steel pipe central part form the air passage. The utility model will be process steel pipe of central part and be equipped with the combination of multistage, can satisfy the demand of different length slender hole casting, effectively increase its applicability.

Description

Technical Field

[0001] This utility model relates to the field of casting technology, and more specifically to a sand core structure for casting slender holes. Background Technology

[0002] In the casting industry, sand cores are key tooling for forming the internal cavity or complex channel of castings. Their structural design and performance directly affect the dimensional accuracy, surface quality and production efficiency of castings. For castings with slender holes, sand cores need to meet contradictory requirements such as high strength, high permeability and controllable collapse.

[0003] A search revealed Chinese patent CN205393465U, which discloses a sand core structure for forming slender holes in castings. This device can eliminate the defects of ordinary sand cores, such as low surface refractoriness, easy burning, burning through, erosion, or breakage by high-temperature molten iron. It also facilitates the recycling and reuse of sand and process steel pipes, uses less sand, and has low casting costs. However, the length of the process steel pipe inside the device is fixed, requiring different lengths of process steel pipes when casting slender holes of different lengths, resulting in low applicability. Utility Model Content

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a sand core structure for casting slender holes to solve the problems existing in the background art.

[0005] This utility model provides the following technical solution: a sand core structure for casting slender holes, comprising multiple process steel pipes. The bottom of each process steel pipe is detachably connected to an external threaded ring via bolts. The top of each process steel pipe has an annular threaded groove that mates with the external threaded ring. The bottom of the process steel pipe does not have an annular threaded groove. The top of the process steel pipe is threaded to a top steel pipe via an external threaded ring identical to the bottom of the top steel pipe. The top steel pipe is replaceable. A venting channel is formed at the center of the multiple process steel pipes and the top steel pipe. Multiple sets of vent holes that mate with the venting channel are formed on the outer circumference of the multiple process steel pipes. Each set consists of multiple holes arranged in a ring array. A sand core layer with a certain degree of collapsibility is provided on the outer side of the structure composed of the process steel pipes and the top steel pipe.

[0006] As a further embodiment of this utility model, each of the multiple process steel pipes is fixedly connected with an inlay strip on its inner circumference. Each of the two inlay strips has a square groove on its opposite side, and the bottom of the square groove is closed. Each of the two square grooves is slidably connected with a slide bar. Two upper and lower support frames are fixedly connected between the opposite sides of the two slide bars. The upper support frame is provided with a detaching component.

[0007] As a further embodiment of this utility model, the picking component includes a fixing strip fixedly connected to the inner wall of one side of the support frame, and a fixing ring is fixedly connected to the top end of the fixing strip.

[0008] As a further embodiment of this utility model, both sides of the fixing strip are fixedly connected with supporting ribs for increasing strength, and the other ends of the two supporting ribs are respectively fixed to the inner walls of the two sides of the support frame.

[0009] As a further embodiment of this utility model, the slider and the inner wall of the square groove are fitted together with a tight clearance to form a sliding pair, and the contact surface generates Coulomb friction through a material with a high coefficient of friction.

[0010] As a further embodiment of this utility model, the process steel pipe is composed of an outer layer and an inner layer arranged coaxially. The outer layer is a heat insulation layer made of high-temperature heat insulation material, and its thermal conductivity is lower than that of the inner layer. The inner layer is a high-strength structural layer used to provide the axial bearing capacity and deformation resistance of the steel pipe, and is made of a metal material with higher mechanical strength than the outer layer.

[0011] The technical effects and advantages of this utility model are as follows:

[0012] 1. This utility model sets the process steel pipe in the central part as a multi-segment combination, which can meet the needs of casting slender holes of different lengths and effectively increase its applicability.

[0013] 2. This utility model achieves precise disintegration of the sand core layer within a specific temperature range through the synergistic effect of resin and disintegrating agent, avoiding premature disintegration that affects casting molding or late residue that leads to cleaning difficulties, thereby facilitating the removal and reuse of the assembled internal process steel pipe.

[0014] 3. This utility model sets the process steel pipe as an inner and outer layer. The outer layer of heat insulation material effectively isolates the high-temperature environment of casting, while the inner layer of high-strength metal matrix provides structural support, solving the technical problem that a single material cannot take into account both heat insulation and strength. Furthermore, it is used in conjunction with the internal support frame to further increase the strength of the process steel pipe.

[0015] 4. This utility model uses a sliding pair design of slider and square groove, which allows the support frame to be quickly disassembled and assembled, reducing maintenance costs. The high friction coefficient coating and clearance fit work together to prevent the support frame from shifting during the casting process. Attached Figure Description

[0016] Figure 1 This is a three-dimensional sectional view of the present invention.

[0017] Figure 2 This is a schematic diagram of the exploded structure of the process steel pipe of this utility model.

[0018] Figure 3 This is a cross-sectional structural diagram of the process steel pipe of this utility model.

[0019] Figure 4This is a schematic diagram of the internal structure of the steel pipe used in this utility model.

[0020] Figure 5 This utility model Figure 3 A partially enlarged structural diagram.

[0021] The attached diagram is labeled as follows: 1. Sand core layer; 2. Process steel pipe; 3. Top steel pipe; 4. Ventilation hole; 5. External threaded ring; 6. Annular threaded groove; 7. Inlay strip; 8. Square groove; 9. Sliding strip; 10. Support frame; 11. Pick-up assembly; 12. Fixing strip; 13. Fixing ring; 14. Support rib; 15. Inner layer; 16. Outer layer. Detailed Implementation

[0022] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings. In addition, the forms of the various structures described in the following embodiments are merely illustrative. This utility model is not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0023] Reference Figures 1-5This utility model provides a sand core structure for casting slender holes, including multiple process steel pipes 2. The process steel pipes 2 are made of seamless stainless steel pipes with a wall thickness of 3-5mm, and their outer diameter matches the inner diameter of the sand core layer 1. The bottom of the process steel pipe 2 is detachably connected to an external threaded ring 5 by bolts. The top of the process steel pipe 2 is provided with an annular threaded groove 6 that cooperates with the external threaded ring 5. The bottom process steel pipe 2 does not have an annular threaded groove 6 at its bottom, and the top of the process steel pipe 2 is threadedly connected to the same external threaded ring 5 as its bottom. The structure includes a top steel pipe 3, which is replaceable. Multiple process steel pipes 2 and the top steel pipe 3 form an air outlet channel at their center. Multiple sets of vent holes 4, arranged in a ring array, are opened on the outer circumference of the process steel pipes 2 to cooperate with the air outlet channel. The outer side of the structure composed of the process steel pipes 2 and the top steel pipe 3 is provided with a sand core layer 1 with a certain degree of collapsibility. The sand core layer 1 is made of resin, a collapsible agent, additives, and sand in a specific ratio. Through the synergistic effect of the resin and the collapsible agent, the sand core layer 1 achieves its collapsibility within a specific temperature range. Precise disintegration avoids premature collapse affecting casting formation or excessive residue leading to cleaning difficulties, thus facilitating the removal and reuse of internal process steel pipes. After the internal parts of process steel pipe 2 are installed, multiple process steel pipes 2 are threaded from bottom to top using external threaded rings 5 ​​and annular threaded grooves 6. Finally, a top steel pipe 3 of matching length is taken out and threaded onto the topmost part. Then, the sand core layer 1 is fitted onto the outside of the assembly, with the two in close contact. After pouring, the disintegration layer is heated by the high temperature of the molten metal. The process (≥600℃) involves the carbonization and decomposition of the resin binder, while the carbonate disintegrating agent decomposes upon heating, releasing CO2 gas. The gas expansion causes the bonding between sand grains to fail, resulting in the overall disintegration of the sand core layer 1. After casting, when the pressure is maintained and cooled to 400-500℃, the sand core layer 1 begins to disintegrate. At room temperature, the residual strength is ≤0.5MPa, which can be removed by slight vibration or airflow purging. The process steel pipe 2 in the central part is designed as a multi-segment combination, which can meet the needs of casting slender holes of different lengths and effectively increase its applicability.

[0024] In this invention, multiple process steel pipes 2 are each welded with inlaid strips 7 on their inner circumference. Square grooves 8 are formed on opposite sides of two inlaid strips 7, with the bottom of the grooves 8 closed. Sliding strips 9 are slidably connected within each of the two square grooves 8. Two upper and lower support frames 10 are bolted together between the opposite sides of the two sliding strips 9. A detachable assembly 11 is provided on the upper support frame 10. The sliding strips 9 and the inner wall of the square grooves 8 form a sliding pair with a tight clearance fit. Coulomb friction is generated at the contact surface through a high-friction coefficient material. In use, two rectangular inlaid strips 7 are symmetrically welded axially onto the inner circumference of the steel pipe. Through-type square grooves 8 are machined on the opposite sides of the two inlaid strips 7, with an appropriate sealing thickness at the bottom of the grooves to prevent the sliding strips 9 from detaching. Then, the two support frames 10 are installed between the two sliding strips 9. Through the sliding pair design between the sliding strips 9 and the square grooves 8, the support frames can be quickly disassembled and reassembled, reducing... Low maintenance cost, high friction coefficient coating and clearance fit work together to prevent displacement of support frame 10 during casting. Both sides of the fixing strip 12 are fixed with support ribs 14 for increasing strength by bolts. The other ends of the two support ribs 14 are fixed to the inner walls of the two sides of the support frame 10 respectively. The pick-up component 11 includes a fixing strip 12 fixed to the inner wall of one side of the support frame 10 by bolts. The top of the fixing strip 12 is welded with a fixing ring 13. After the support frame 10 is installed, the fixing strip 12 is installed on the upper support frame 10. Then the fixing ring 13 and support ribs 14 are installed on the fixing strip 12. Then the assembled component is slid into the bottom of the square groove 8 from the top of the side slides 9. The surface of the slides 9 is sprayed with polyurethane coating. The high friction coefficient of the slides forms Coulomb friction damping with the inner wall of the square groove 8 to prevent spontaneous displacement of the support frame 10 during operation.

[0025] In this invention, the process steel pipe 2 is composed of an outer layer 16 and an inner layer 15 arranged coaxially. The outer layer 16 is a heat insulation layer used to block external heat from being conducted into the steel pipe. It is made of a high-temperature resistant heat insulation material with a lower thermal conductivity than the inner layer 15. The inner layer 15 is a high-strength structural layer used to provide the axial load-bearing capacity and deformation resistance of the steel pipe. It is made of a metal material with higher mechanical strength than the outer layer 16. By setting the process steel pipe 2 into two layers, the heat insulation material of the outer layer 16 effectively isolates the high-temperature environment of casting, while the high-strength metal matrix of the inner layer 15 provides structural support. This solves the technical problem that a single material cannot simultaneously provide both heat insulation and strength. Furthermore, it is used in conjunction with the internal support frame 10 to further increase the strength of the process steel pipe 2.

[0026] The use of this utility model involves the following steps:

[0027] S1: When in use, two rectangular strips 7 are symmetrically welded along the axial direction on the inner wall of the steel pipe. A through square groove 8 is processed on the opposite side of the two strips 7. The bottom of the groove retains an appropriate sealing thickness to prevent the slide bar 9 from falling out. Then, two support frames 10 are installed between the two slide bars 9.

[0028] S2: After the support frame 10 is installed, the fixing strip 12 is installed on the upper support frame 10. Then, the fixing ring 13 and the support rib 14 are installed on the fixing strip 12. Then, the assembled parts are slid into the bottom of the square groove 8 from the top through the sliding strips 9 on both sides. The surface of the sliding strip 9 is sprayed with polyurethane coating. Its high coefficient of friction forms Coulomb friction damping with the inner wall of the square groove 8 to prevent the support frame 10 from spontaneously displacing during operation.

[0029] S3: After the internal parts of the process steel pipe 2 are installed, multiple process steel pipes 2 are threaded from bottom to top through the external thread ring 5 and the annular thread groove 6. Finally, according to the required length, the top steel pipe 3 of the matching length is taken out and threaded to the top. Then, the sand core layer 1 is fitted onto the outside of the assembly, and the two are in close contact.

[0030] S4: After casting, the collapsible layer is subjected to the thermal action of high-temperature molten metal (≥600℃), the resin binder carbonizes and decomposes, and at the same time the carbonate collapsible agent decomposes under heat and releases CO2 gas. The gas expansion causes the bonding between sand grains to fail, resulting in the overall collapse of sand core layer 1. When the sand core layer 1 is held under pressure and cooled to 400-500℃ after casting, the collapse begins to disintegrate. The residual strength at room temperature is ≤0.5MPa, which can be removed by slight vibration or airflow purging.

[0031] Finally, the following points should be noted: In the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection" and "linkage" should be interpreted broadly, and can be mechanical or electrical connection, or internal connection between two components, or direct connection. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationship. When the absolute position of the described object changes, the relative positional relationship may change.

[0032] The electronic components and modules used in this utility model can all be parts that are commonly used in the market and can achieve the specific functions in this case. The specific models and sizes can be selected and adjusted according to actual needs.

[0033] The accompanying drawings of the embodiments disclosed in this utility model only involve the structures involved in the embodiments disclosed in this utility model. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this utility model can be combined with each other.

Claims

1. A sand core structure for casting slender holes, comprising multiple process steel pipes (2), characterized in that: The bottom of the process steel pipe (2) is detachably connected to an external threaded ring (5) by bolts. The top of the process steel pipe (2) is provided with an annular threaded groove (6) that cooperates with the external threaded ring (5). The bottom of the process steel pipe (2) located at the bottom does not have an annular threaded groove (6). The top of the process steel pipe (2) located at the top is connected to a top steel pipe (3) by an external threaded ring (5) that is the same as the bottom. The top steel pipe (3) is replaceable. The central part of the multiple process steel pipes (2) and the top steel pipe (3) forms an air outlet channel. Multiple sets of vent holes (4) that cooperate with the air outlet channel are opened on the outer circumference of the multiple process steel pipes (2). Each set consists of multiple holes arranged in an annular array. The outer side of the structure composed of the process steel pipe (2) and the top steel pipe (3) is provided with a sand core layer (1) with a certain degree of collapsibility.

2. The sand core structure for casting slender holes according to claim 1, characterized in that: Inlay strips (7) are fixedly connected to the inner circumference of multiple process steel pipes (2). Square grooves (8) are opened on the opposite sides of two inlay strips (7), and the bottom end of the square grooves (8) is closed. Sliding strips (9) are slidably connected in the two square grooves (8). Two upper and lower support frames (10) are fixedly connected between the opposite sides of the two sliding strips (9). A take-up assembly (11) is provided on the upper support frame (10).

3. The sand core structure for casting slender holes according to claim 2, characterized in that: The picking component (11) includes a fixing strip (12) fixedly connected to the inner wall of one side of the support frame (10), and a fixing ring (13) is fixedly connected to the top end of the fixing strip (12).

4. The sand core structure for casting slender holes according to claim 3, characterized in that: Both sides of the fixing strip (12) are fixedly connected with support ribs (14) for increasing strength, and the other ends of the two support ribs (14) are respectively fixed to the inner walls of the two sides of the support frame (10).

5. The sand core structure for casting slender holes according to claim 2, characterized in that: The slider (9) and the inner wall of the square groove (8) are fitted together with a tight clearance to form a sliding pair, and the contact surface generates Coulomb friction through a material with a high coefficient of friction.

6. The sand core structure for casting slender holes according to claim 1, characterized in that: The process steel pipe (2) is composed of an outer layer (16) and an inner layer (15) arranged coaxially. The outer layer (16) is a heat insulation layer made of high-temperature heat insulation material, and its thermal conductivity is lower than that of the inner layer (15). The inner layer (15) is a high-strength structural layer used to provide the axial bearing capacity and deformation resistance of the steel pipe, and is made of a metal material with higher mechanical strength than the outer layer (16).

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