Casting sand mold structure for stepped casting of thin-wall steel casting

Abstract

The utility model discloses a casting sand mold structure for stepped casting of a thin-wall steel casting, which belongs to the technical field of casting and comprises a sand mold with a cavity. The pouring pipeline is arranged in the sand mold and comprises a main pouring gate, and the main pouring gate is provided with a bottom pouring gate communicated with the mold cavity and a second-layer pouring gate located above the bottom pouring gate; a reducing section of which the inner diameter is gradually reduced along the downward direction is arranged on the part, between the bottom pouring gate and the two-layer pouring gate, of the main pouring gate; a protruding gasket is arranged on the inner wall face of the reducing section. The diameter of the plugging steel ball is smaller than the inner diameter of the uppermost end of the reducing section and larger than the inner diameter of the lowermost end of the reducing section; in the pouring process, when molten steel rises to the position of a second-layer pouring gate, the plugging steel ball is placed in the main pouring gate, the plugging steel ball falls down and is clamped at the variable-diameter section to plug the bottom pouring gate, the gasket can effectively buffer the impact force of the plugging steel ball, the inner wall of the variable-diameter section cannot be damaged, and the service life of the plugging steel ball is prolonged. And the temperature gradient of the molten steel in the cavity meets the requirement.

Description

Technical Field

[0001] The utility model relates to the technical field of casting devices, in particular to a step casting and pouring sand mold structure for thin-walled steel castings. Background Art

[0002] Steel castings are a type of workpiece produced using a casting method. Steel castings have the characteristics of large shrinkage, easy to produce shrinkage and shrinkage cavities, etc. Therefore, in actual production, in order to obtain better shrinkage compensation efficiency and temperature gradient, a stepped casting sand mold structure is used. During pouring, the molten steel first enters the mold cavity from the bottom runner. When the molten steel rises to the position of the second runner, it enters the mold cavity from the second runner. This makes the upper layer of the molten steel in the mold cavity high in temperature and the lower layer low in temperature, and the temperature gradient is better; however, this pouring system also has the following problems: when the molten steel can enter the mold cavity from the second runner, under the action of gravity, part of the molten steel will continue to flow downward, and the molten steel will not completely enter the mold cavity from the second runner, causing the temperature gradient of the molten steel in the mold cavity to fail to meet the requirements, and the casting is prone to defects such as shrinkage cavities and shrinkage.

[0003] Thin-walled steel castings, such as the thin-walled cast steel volute structure of a gas turbine, require a wall thickness of 15 mm. Considering the operating conditions of this type of volute and the design dimensions of the volute itself, the control of the wall thickness becomes the top priority of the casting process. If the conventional stepped casting sand mold structure is used to produce this type of volute, the temperature gradient of the molten steel in the mold cavity is difficult to meet the requirements, there is a great risk of wall penetration and scrap, and the size is very easy to deform.

[0004] Patent CN205732941U discloses a layered pouring device for steel castings. The pouring tube is sealed with a blocking steel ball to prevent molten steel from entering the mold cavity from the bottom runner. However, the blocking steel ball falls quickly and has a great impact on the inner wall of the pouring tube when it contacts the inner wall of the pouring tube, which can easily cause cracks on the inner wall of the pouring tube and affect the service life of the pouring tube. In addition, the runner on the top is arranged horizontally, and there is a risk that the molten steel will enter the mold cavity prematurely during the pouring process.

[0005] Therefore, it is an urgent problem to be solved at this stage to develop and design a sand mold structure that can make the temperature gradient of the molten steel in the mold cavity meet the requirements, will not damage the inner wall of the reducing section, strictly guarantee the wall thickness requirements and quality control requirements, avoid the production of shrinkage cavities, shrinkage and other defects in thin-walled steel castings, and avoid dimensional deformation. Utility Model Content

[0006] In order to solve the problems existing in the prior art, the utility model provides a stepped casting sand mold structure for thin-walled steel castings, wherein a main runner is connected to the mold cavity through a bottom runner and a second-layer runner respectively. During the pouring process, when the molten steel rises to the position of the second-layer runner, a sealing steel ball is placed in the main runner, and the sealing steel ball falls and is stuck at the reducing section to seal the bottom runner. The gasket can effectively buffer the impact force of the sealing steel ball, and the inner wall of the reducing section will not be damaged. The temperature gradient of the molten steel in the mold cavity meets the requirements, thereby avoiding the occurrence of shrinkage cavities, shrinkage and other defects in thin-walled steel castings and ensuring the wall thickness requirements.

[0007] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0008] The utility model provides a step casting sand mold structure for thin-walled steel castings, comprising:

[0009] A sand mold, wherein the sand mold has a mold cavity;

[0010] A pouring pipe, the pouring pipe is arranged in the sand mold; the pouring pipe includes a main runner, the upper end of the main runner forms a pouring port, the main runner is provided with a bottom runner and a second-layer runner connected to the mold cavity, the second-layer runner is located above the bottom runner; the main runner has a variable diameter section on a portion located between the bottom runner and the second-layer runner; the inner diameter of the variable diameter section gradually decreases in a downward direction; a washer with a convex arrangement is provided on the inner wall surface of the variable diameter section;

[0011] A sealing steel ball, wherein the diameter of the sealing steel ball is smaller than the inner diameter of the uppermost end of the diameter-changing section, and the diameter of the sealing steel ball is larger than the inner diameter of the lowermost end of the diameter-changing section.

[0012] As a preferred technical solution, it also includes a funnel-shaped pouring cup, and the lower end of the pouring cup is connected to the pouring port.

[0013] As a preferred technical solution, it also includes an inclined guide rail, the lowermost end of which is arranged at the pouring cup; and the blocking steel ball is arranged on the guide rail.

[0014] As a preferred technical solution, a placement groove is provided on the side wall of the pouring cup at a position corresponding to the lowermost end of the guide rail, and the lowermost end of the guide rail is placed on the placement groove.

[0015] As a preferred technical solution, the width of the placement groove is set to 150 mm;

[0016] And / or, a baffle capable of preventing the blocking steel ball from rolling is provided on the guide rail;

[0017] And / or, a plurality of deceleration protrusions are provided on the surface of the guide rail near its lower end.

[0018] As a preferred technical solution, the upper end surface of the gasket is set to be an arc-shaped curved surface matching the blocking steel ball;

[0019] And / or, a support frame is provided at the lower end of the gasket, and the cross-section of the support frame is triangular.

[0020] As a preferred technical solution, the main runner is vertically arranged, and the pouring port is located on the upper surface of the sand mold.

[0021] As a preferred technical solution, the bottom runner has a curved section, the curved section is arc-shaped, and the bending angle of the curved section is set to 90°;

[0022] And / or, the second-layer runner has an inclined section, and the inclined section is arranged to be inclined upward along the direction from the main runner to the cavity;

[0023] And / or, the material of the pouring pipe is set to ceramic;

[0024] And / or, the inner diameter of the portion of the main runner located above the diameter-changing section is greater than the diameter of the sealing steel ball.

[0025] As a preferred technical solution, the sealing steel ball is configured as a hollow structure.

[0026] As a preferred technical solution, the diameter of the sealing steel ball is set to 120 mm; the inner diameter of the uppermost end of the variable diameter section is set to 130 mm, and the inner diameter of the lowermost end of the variable diameter section is set to 110 mm.

[0027] The beneficial effects of the utility model are as follows:

[0028] 1. The main runner of the utility model is connected with the mold cavity through the bottom runner and the second-layer runner respectively. During the pouring process, the molten steel first enters the mold cavity from the bottom runner. When the molten steel in the mold cavity rises to the position of the second-layer runner, a blocking steel ball is placed in the main runner. The blocking steel ball falls under the action of gravity and is stuck at the reducing section to block the bottom runner. The gasket can effectively buffer the impact force of the blocking steel ball, the inner wall of the reducing section will not be damaged, and the falling process of the blocking steel ball will not cause excessive impact on the molten steel, so that the temperature gradient of the molten steel in the mold cavity meets the requirements, so that the thin-walled steel casting has a good solidification gradient, and the defects of shrinkage cavities and shrinkage porosity in the thin-walled steel casting are avoided, and the size deformation of the thin-walled steel casting is avoided, and the wall thickness requirements and quality control requirements are guaranteed.

[0029] 2. The utility model utilizes a plurality of deceleration protrusions on the surface of the guide rail near its lower end, which can effectively reduce the initial speed of the blocking steel ball when it falls from the guide rail into the main runner, and can further reduce the impact force of the blocking steel ball on the main runner, thereby increasing the service life of the main runner.

[0030] 3. The utility model uses guide rails, pouring cups and other tools to achieve the process of blocking the steel ball falling into the main pouring channel and blocking the bottom pouring channel, which simplifies the operation and greatly improves the operability and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of an embodiment of a step casting sand mold structure for thin-walled steel castings of the utility model;

[0032] Figure 2 for Figure 1 A schematic diagram of the structure in which the plugging steel ball is stuck at the diameter reducing section;

[0033] Figure 3 for Figure 1 The structural diagram of the pouring pipeline in FIG.

[0034] Figure 4 for Figure 3 A magnified image of area A;

[0035] Figure 5 for Figure 1 A schematic diagram of the structure of the pouring cup;

[0036] Figure 6 for Figure 1 Schematic diagram of the structure of the guide rail.

[0037] In the figure: 1-sand mold, 11-mold cavity, 2-main runner, 21-pouring gate, 22-diameter reducing section, 3-bottom runner, 31-bending section, 4-two-layer runner, 41-inclined section, 5-sealing steel ball, 6-pouring cup, 61-placing groove, 7-guide rail, 71-baffle, 72-deceleration protrusion, 8-washer, 81-arc-shaped surface, 82-support frame. DETAILED DESCRIPTION

[0038] In order to facilitate understanding by those skilled in the art, the present invention is further described below in conjunction with the accompanying drawings.

[0039] Please refer to Figure 1-Figure 6, is an embodiment of a step casting sand mold structure for thin-walled steel castings provided by the utility model, comprising a sand mold 1, wherein the sand mold 1 has a mold cavity 11; a pouring pipe is arranged in the sand mold 1; the pouring pipe comprises a main runner 2, wherein a pouring port 21 is formed at the upper end of the main runner 2, and a bottom runner 3 and a second-layer runner 4 connected to the mold cavity 11 are arranged on the main runner 2, wherein the second-layer runner 4 is located above the bottom runner 3, and molten steel enters the main runner 2 from the pouring port 21, and successively flows into the mold cavity 11 from the bottom runner 3 and the second-layer runner 4; the main runner 2 is located between the bottom runner 3 and the second-layer runner 4 The part between the two parts is provided with a reducing section 22, the inner diameter of the reducing section 22 gradually decreases in the vertical downward direction, the diameter of the blocking steel ball 5 is smaller than the inner diameter of the uppermost end of the reducing section 22, and the diameter of the blocking steel ball 5 is larger than the inner diameter of the lowermost end of the reducing section 22. A washer 8 with a raised arrangement is provided on the inner wall surface of the reducing section 22. After the blocking steel ball 5 falls into the main runner 2, it moves downward under the action of gravity and abuts against the washer 8 at the reducing section 22, thereby blocking the bottom runner 3 and realizing the stepped pouring of molten steel; the washer 8 can effectively buffer the impact force of the blocking steel ball 5 and avoid damage to the inner wall of the reducing section 22.

[0040] For details, please refer to Figure 1-Figure 3 The main runner 2 is vertically arranged, and the pouring port 21 is located at the upper surface of the sand mold 1, so as to facilitate the injection of molten steel. In other embodiments, the main runner 2 can also be inclined so that the molten steel can be stably and continuously injected into the mold cavity 11.

[0041] For further information, please refer to Figure 1-Figure 3 The bottom runner 3 has a curved section 31, which is arc-shaped. The bending angle of the curved section 31 is set to 90°. The curved section 31 can guide the molten steel so that the molten steel flows into the cavity 11 in a horizontal direction to avoid scouring the cavity 11; at the same time, the second-layer runner 4 has an inclined section 41, and the inclined section 41 is inclined upward along the direction from the main runner 2 to the cavity 11. Before the molten steel rises to the second-layer runner 4, the inclined section 41 can prevent the molten steel from flowing into the cavity 11 from the second-layer runner 4 in advance during the pouring process, thereby protecting the step pouring of the cavity 11.

[0042] It should be noted that the materials of the pouring pipe, gasket 8 and support frame 82 are preferably set to ceramic, which can effectively withstand high-temperature molten steel and is low in cost; in actual production, the sealing steel ball 5 is a consumable part. After the sealing steel ball 5 falls into the main runner 2, the pouring process will be completed in no more than one minute. The sealing steel ball 5 will not melt but part of the solidified molten steel will adhere to the surface. Therefore, the sealing steel ball 5 is preferably set to a hollow structure, which can reduce production costs and also reduce the impact force of the sealing steel ball 5 on the gasket 8.

[0043] In this embodiment, please refer to Figure 1 , Figure 2 and Figure 5The utility model further comprises a funnel-shaped pouring cup 6 , the lower end of which is connected to the pouring port 21 . The funnel-shaped pouring cup 6 can more conveniently inject molten steel into the main runner 2 .

[0044] Based on the above examples, please refer to Figure 1 , Figure 2 and Figure 6 The utility model also includes an inclined guide rail 7, which is placed on the sand mold 1, and the lowermost end of the guide rail 7 is arranged at the pouring cup 6; the blocking steel ball 5 is arranged on the guide rail 7, and the blocking steel ball 5 rolls along the guide rail 7 to fall into the pouring cup 6 and enter the main runner 2; further, the surface of the guide rail 7 near its lower end is preferably provided with a plurality of deceleration protrusions 72 distributed along the extension direction of the guide rail 7, and the plurality of deceleration protrusions 72 form a "speed bump" for the blocking steel ball 5, which can effectively reduce the initial speed of the blocking steel ball 5 when it falls from the guide rail 7 into the main runner 2, reduce the impact force of the blocking steel ball 5 on the main runner 2, and increase the service life of the main runner 2.

[0045] For details, please refer to Figure 1 , Figure 2 and Figure 5 A placement groove 61 is preferably provided on the side wall of the pouring cup 6 at a position corresponding to the lower end of the guide rail 7, and the lower end of the guide rail 7 is placed on the placement groove 61, which is convenient for relatively fixing the pouring cup 6 and the guide rail 7 to ensure that the blocking steel ball 5 rolling down along the guide rail 7 can fall into the pouring cup 6.

[0046] For further information, please refer to Figure 1 and Figure 6 The guide rail 7 is preferably provided with a baffle 71 capable of preventing the blocking steel ball 5 from rolling. When the molten steel in the cavity 11 rises to the position of the second-layer runner 4, the baffle 71 is removed, and the blocking steel ball 5 can automatically fall into the reducing section 22 to block the bottom runner 3.

[0047] Specifically, the diameter of the sealing steel ball 5 is preferably set to 120 mm. Correspondingly, the inner diameter of the portion of the main runner 2 located above the variable diameter section 22 is larger than the diameter of the sealing steel ball 5. The inner diameter of the uppermost end of the variable diameter section 22 is set to 130 mm, and the inner diameter of the lowermost end of the variable diameter section 22 is set to 110 mm, to ensure that the sealing steel ball 5 can be stuck in the variable diameter section 22; at the same time, the width of the placement groove 61 is set to 150 mm, which is convenient for placing the guide rail 7 and ensuring that the sealing steel ball 5 falls smoothly into the pouring cup 6.

[0048] In this embodiment, please refer to Figure 1-Figure 4The upper end surface of the gasket 8 is set to an arc-shaped curved surface 81 that matches the sealing steel ball 5. When the sealing steel ball 5 is stuck in the reducing section 22, it fits tightly with the upper end surface of the gasket 8 to improve the sealing effect; further, a support frame 82 is provided at the lower end of the gasket 8. The cross-section of the support frame 82 is triangular. The support frame 82 can effectively support the gasket 8, withstand the impact force of the sealing steel ball 5 on the gasket 8, and improve the structural strength of the gasket 8. The gasket 8 and the support frame 82 are preferably annular structures.

[0049] Please refer to Figure 1 and Figure 2 , the specific working mode of the utility model is as follows:

[0050] Before pouring, calculate in advance the weight of the molten steel when it reaches the second-layer runner 4;

[0051] The lower end of the pouring cup 6 is connected to the pouring port 21, and the guide rail 7 is placed on the sand mold 1 so that the lowest end of the guide rail 7 is placed at the placement groove 61 of the pouring cup 6; the blocking steel ball 5 is placed on the guide rail 7 and positioned with the baffle 71;

[0052] During the pouring process, when the weight of the poured molten steel reaches the weight of the molten steel when it reaches the second-layer runner 4 calculated in advance, the baffle 71 on the guide rail 7 is removed, and the sealing steel ball 5 falls into the pouring cup 6 along the guide rail 7, and moves steadily downward along the main runner 2 under the action of gravity and gets stuck at the gasket 8 of the reducing section 22, thereby blocking the bottom runner 3, so that the molten steel can only pass through the second-layer runner 4 cavity 11, so that the temperature gradient of the molten steel in the cavity 11 meets the requirements, thereby realizing step pouring.

[0053] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A step casting sand mold structure for thin-walled steel castings, characterized in that: include: A sand mold (1), wherein the sand mold (1) has a mold cavity (11); A pouring pipe, the pouring pipe is arranged in the sand mold (1); the pouring pipe comprises a main pouring channel (2), the upper end of the main pouring channel (2) forms a pouring port (21), the main pouring channel (2) is provided with a bottom pouring channel (3) and a second-layer pouring channel (4) which are connected to the mold cavity (11), the second-layer pouring channel (4) is located above the bottom pouring channel (3); the main pouring channel (2) has a diameter-changing section (22) at a portion located between the bottom pouring channel (3) and the second-layer pouring channel (4); the inner diameter of the diameter-changing section (22) gradually decreases in a downward direction; a protruding gasket (8) is provided on the inner wall surface of the diameter-changing section (22); A sealing steel ball (5), wherein the diameter of the sealing steel ball (5) is smaller than the inner diameter of the uppermost end of the diameter-changing section (22), and the diameter of the sealing steel ball (5) is larger than the inner diameter of the lowermost end of the diameter-changing section (22).

2. A step casting sand mold structure for thin-walled steel castings according to claim 1, characterized in that: It also comprises a funnel-shaped pouring cup (6), the lower end of the pouring cup (6) being connected to the pouring port (21).

3. A step casting sand mold structure for thin-walled steel castings according to claim 2, characterized in that: It also comprises an inclined guide rail (7), the lowermost end of which is arranged at the pouring cup (6); and the blocking steel ball (5) is arranged on the guide rail (7).

4. A step casting sand mold structure for thin-walled steel castings according to claim 3, characterized in that: A placement groove (61) is provided on the side wall of the pouring cup (6) at a position corresponding to the lowermost end of the guide rail (7), and the lowermost end of the guide rail (7) is placed on the placement groove (61).

5. The step casting sand mold structure for thin-walled steel casting according to claim 4, characterized in that: The width of the placement groove (61) is set to 150 mm; And / or, a baffle (71) capable of preventing the blocking steel ball (5) from rolling is provided on the guide rail (7); And / or, a plurality of deceleration protrusions (72) are provided on the surface of the guide rail (7) near its lower end.

6. The step casting sand mold structure for thin-walled steel casting according to claim 1, characterized in that: The upper end surface of the gasket (8) is set as an arc-shaped curved surface (81) matching the sealing steel ball (5); And / or, a support frame (82) is provided at the lower end of the gasket (8), and the cross-section of the support frame (82) is triangular.

7. The step casting sand mold structure for thin-walled steel casting according to claim 1, characterized in that: The main runner (2) is arranged vertically, and the pouring port (21) is located on the upper surface of the sand mold (1).

8. A step casting sand mold structure for thin-walled steel castings according to claim 1 or 7, characterized in that: The bottom runner (3) has a curved section (31), the curved section (31) is arc-shaped, and the bending angle of the curved section (31) is set to 90°; And / or, the second-layer runner (4) has an inclined section (41), and the inclined section (41) is arranged to be inclined upward along the direction from the main runner (2) to the mold cavity (11); And / or, the material of the pouring pipe is set to ceramic; And / or, the inner diameter of the portion of the main runner (2) located above the diameter-changing section (22) is greater than the diameter of the blocking steel ball (5).

9. The step casting sand mold structure for thin-walled steel casting according to claim 1, characterized in that: The blocking steel ball (5) is designed as a hollow structure.

10. The step casting sand mold structure for thin-walled steel casting according to claim 1, characterized in that: The diameter of the blocking steel ball (5) is set to 120 mm; the inner diameter of the uppermost end of the diameter-changing section (22) is set to 130 mm, and the inner diameter of the lowermost end of the diameter-changing section (22) is set to 110 mm.

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