Sand mold for vacuum pump shell casting

Abstract

The utility model provides a sand mold for a vacuum pump shell casting. The sand mold for the vacuum pump shell casting comprises a sand core integrally formed through 3D printing, the interior of the sand core is hollow, the positions, close to the two ends, of the sand core are sealed, through holes are formed in the sealing positions of the sand core, and the through holes in the two ends of the sand core are located on the same line in a one-to-one correspondence mode; the two ends of the core bar are located outside the sealing position of the sand core and connected with limiting workpieces. According to the utility model, the original split type sand core combination mode is changed into the 3D printing integral sand core, so that the combination is not needed, and the matching error is reduced; the surface precision of the 3D printing sand core is higher than that of a resin sand molding sand core, and the smoothness of the inner surface of the shell can be greatly guaranteed; the interior of the sand core is of a hollow structure, use of sand is reduced, cost is reduced, and meanwhile the core bars are added in the sand core for supporting, so that the sand core is not prone to damage.

Description

Technical Field

[0001] The utility model relates to the technical field of casting molding, in particular to a sand mold for a vacuum pump housing casting. Background Art

[0002] At present, the sand mold molding of vacuum pump housing castings adopts resin sand molding, but the inner cavity smoothness of the vacuum pump housing produced cannot be guaranteed, which is easy to be scrapped, and the resin sand usage is large and the cost is high. In addition, in order to facilitate the molding, a split sand core combination is adopted, that is, two sand cores are molded separately first, and then combined into an integral sand core required for the vacuum pump housing, but there is an error in the combination method. If the error is large, it will affect the subsequent casting operation and may cause the casting preparation to fail. Utility Model Content

[0003] Based on this, it is necessary to provide a sand mold for vacuum pump housing casting to address the problems of large errors and easy scrapping in the existing resin sand split molding of vacuum pump housing.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A sand mold for a vacuum pump housing casting comprises a sand core integrally formed by 3D printing, wherein the interior of the sand core is hollow and sealed near both ends, a through hole is opened at the sealed end of the sand core, the through holes at both ends of the sand core are located in the same linear line in a one-to-one correspondence, and a core bone is provided through the through hole, and both ends of the core bone are located outside the sealed end of the sand core and connected to a limited position workpiece.

[0006] Furthermore, the core bone is made of a steel bar screw rod, and the limiting workpiece is made of a limiting nut, which is threadedly connected to the end of the steel bar screw rod.

[0007] Furthermore, a gasket is sleeved on the outer surface of the core bone, and the gasket is located between the outside of the sand core sealing portion and the limiting nut, and fits with the limiting nut.

[0008] Furthermore, the gap between the core bone and the through hole is filled with resin sand.

[0009] Furthermore, the limiting workpiece adopts a limiting end cap, the limiting end cap is plugged at both ends of the core bone, and the outer wall of the limiting end cap is in contact with the sealing part of the sand core.

[0010] Furthermore, the limiting workpiece adopts a limiting nut and a limiting end cap; the core bone adopts a steel bar screw, the limiting nut is threadedly connected to the end of the steel bar screw, and the limiting end cap is plugged into the end of the core bone and fits tightly with the side of the limiting nut away from the sand core sealing portion.

[0011] Compared with the prior art, the beneficial effects of the utility model include:

[0012] 1. The utility model transforms the original split sand core combination mode into a 3D printed integral sand core, which does not need to be combined and reduces the matching error; the 3D printed sand core has a higher surface accuracy than the resin sand molding sand core, which can greatly ensure the smoothness of the inner surface of the shell;

[0013] 2. The utility model makes the interior of the sand core into a hollow structure, which reduces the use of sand and reduces costs. At the same time, a core bone support is added inside to ensure that the strength of the sand core is not easy to be damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The disclosure of the present invention is described with reference to the accompanying drawings. It should be understood that the drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings, the same reference numerals are used to refer to the same components. Among them:

[0015] Figure 1 It is a schematic diagram of an existing split sand core;

[0016] Figure 2 This is a schematic diagram of the structure of a sand mold for a vacuum pump housing casting introduced in the utility model;

[0017] Figure 3 This is an overall schematic diagram of the sand core introduced in Example 1;

[0018] Figure 4 This is a schematic diagram of the splicing of the limiting end cap and the core bone introduced in Example 2;

[0019] Figure 5 This is a schematic diagram of the splicing of the limiting end cap and the core bone with a stepped inner cavity in Example 2;

[0020] Figure 6 This is a schematic diagram of the limited end cap and nut introduced in Example 3 being spliced ​​with the core bone.

[0021] Notes in the figure: 1. Sand core; 2. Core bone; 3. Limit workpiece; 31. Limit nut; 32. Limit end cap. DETAILED DESCRIPTION

[0022] It is easy to understand that according to the technical solution of the utility model, without changing the essential spirit of the utility model, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the utility model, and should not be regarded as the entirety of the utility model or as a limitation or restriction to the technical solution of the utility model.

[0023] Example 1

[0024] See also Figure 2This embodiment introduces a sand mold for a vacuum pump housing casting, including a 3D printed one-piece sand core 1. The sand core 1 is integrally molded by 3D printing and is integrally molded. Compared with the split sand core, it reduces the combination operation and reduces the matching error. Moreover, the 3D printed sand core 1 has a higher surface accuracy than the resin sand molding sand core 1, which can greatly ensure the smoothness of the inner surface of the housing and reduce the scrap rate.

[0025] In addition, the 3D printed sand core 1 is hollow inside, and the central control structure can reduce the amount of sand used and reduce costs. In order to facilitate the installation of the core bone 2 in the sand core 1 to support the inside of the sand core 1 and ensure that the strength of the sand core 1 is not easily damaged. Inside the sand core 1 and close to the sealing arrangement at both ends, the sealing of the sand core 1 is provided with through holes, and the through holes at the sealing at both ends of the sand core 1 are symmetrically arranged, and the through holes at both ends correspond to each other and are located on the same line, so the core bone 2 can enter from the through hole at one end of the sand core 1 and pass through the through hole at the other end, traversing the internal space of the sand core 1, which is a limited core bone 2. The two ends of the core bone 2 are located outside the sealing of the sand core 1 and connected to the limited workpiece 3.

[0026] like Figure 3 As shown, the limiting workpiece 3 of this embodiment adopts a limiting nut 31, and the core bone 2 adopts a steel bar screw. The limiting nuts 31 are located at both ends of the core bone 2 and are threadedly connected to the core bone 2. The limiting nut 31 is located outside the sealing part of the sand core 1, and a limiting gasket is arranged between the limiting nut 31 and the sealing part of the sand core 1. The limiting gasket is sleeved on the outer surface of the steel bar screw to prevent the limiting nut 31 from directly contacting the sealing part of the sand core 1, and the diameter of the limiting gasket is larger than the diameter of the through hole.

[0027] In order to further fix the steel screw, resin sand is filled in the gap between the steel screw and the through hole, and the steel screw is bonded to the through hole. In actual use, the sand core 1 is placed in the mold box, and the rest is filled with molding sand, the mold cavity and the runner are retained, and molten iron is injected to form and then the sand is removed to obtain the required vacuum pump housing casting.

[0028] Example 2

[0029] like Figure 4 As shown, this embodiment introduces a sand mold for vacuum pump housing casting, which has basically the same structure as the sand mold for vacuum pump housing casting introduced in Example 1. The difference is that the limiting workpiece 3 of this embodiment adopts a limiting end cap 32. The limiting end cap 32 is located at the end of the core bone 2, and the limiting end cap 32 is made of a material with slight elasticity and high temperature resistance. If the diameter of the core bone 2 remains consistent, the inside of the limiting end cap 32 is a cylindrical inner cavity, and the inner diameter of the limiting end cap 32 is consistent with the core bone 2. The gap between the two is matched, and the diameter of the limiting end cap 32 is larger than the diameter of the through hole. It is plugged at the end of the core bone 2 to limit the core bone 2, so that the core bone 2 cannot be separated from the sand core 1. In order to further fix the core bone 2, the gap between the core bone 2 and the through hole can be filled with resin sand.

[0030] like Figure 5 As shown, if the diameter of the core bone 2 has an error, the limiting end cap 32 adopts a limiting end cap 32 with a stepped inner cavity. The outer diameter of the limiting end cap 32 is consistent with the diameter of the through hole. The limiting end cap 32 and the through hole are matched in clearance. The stepped inner cavity gradually reduces in diameter from one end to the other. Adjacent chambers with different diameters are connected by a truncated cone-shaped inner cavity. The truncated cone-shaped design is convenient for guiding the core bone 2 to penetrate. The axial lengths of chambers with different diameters are consistent. The length of the core bone 2 outside the through hole is limited. The length of the core bone 2 outside the sealing part of the sand core 1 is less than the axial length of a chamber in the stepped inner cavity. The setting of the stepped inner cavity can make the limiting end cap 32 adapt to the core bone 2 with an error in diameter. The inner wall of the limiting end cap 32 is matched with the clearance of the core bone 2, and the outer wall is matched with the clearance of the through hole to achieve the limitation of the core bone 2. If there is a gap between the core bone 2 and the limiting end cap 32 or between the through hole and the limiting end cap 32, resin sand can be used for filling. Figure 4 and Figure 5 The diagrams respectively illustrate the clearance fit between core bones of different diameters and cavities of different diameters inside the limiting end cap 32 .

[0031] This embodiment has the same beneficial effects as Embodiment 1.

[0032] Example 3

[0033] like Figure 6 As shown, this embodiment introduces a sand mold for vacuum pump housing casting, which is basically the same as the structure of the sand mold for vacuum pump housing casting introduced in Example 1. The difference is that the limiting workpiece 3 of this embodiment adopts a limiting end cap 32 and a limiting nut 31. The core bone 2 adopts a steel bar screw, the limiting nut 31 is threadedly connected to the end of the steel bar screw, and the limiting end cap 32 is plugged at the end of the core bone and fits tightly with the side of the limiting nut 31 away from the sand core sealing portion.

[0034] This embodiment has the same beneficial effects as Embodiment 1.

[0035] The technical scope of the present invention is not limited to the contents described above. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical concept of the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A sand mold for vacuum pump housing casting, characterized in that: The invention comprises a sand core (1) formed in one piece by 3D printing, wherein the interior of the sand core (1) is hollow and sealed near both ends, a through hole is provided at the sealed end of the sand core (1), the through holes at both ends of the sand core (1) correspond to each other and are located on the same linear line, a core bone (2) is provided through the through hole, and both ends of the core bone (2) are located outside the sealed end of the sand core (1) and are connected to a limited position workpiece (3).

2. The sand mold for vacuum pump housing casting according to claim 1, characterized in that: The core bone (2) is a steel bar screw rod, and the limiting workpiece (3) is a limiting nut (31), which is threadedly connected to the end of the steel bar screw rod.

3. The sand mold for vacuum pump housing casting according to claim 2, characterized in that: The outer surface of the core bone (2) is covered with a gasket, which is located between the outside of the sealing part of the sand core (1) and the limiting nut (31) and fits with the limiting nut (31).

4. The sand mold for vacuum pump housing casting according to claim 1, characterized in that: The gap between the core bone (2) and the through hole is filled with resin sand.

5. The sand mold for vacuum pump housing casting according to claim 1, characterized in that: The limiting workpiece (3) adopts a limiting end cap (32), which is plugged at both ends of the core bone (2), and the end of the limiting end cap (32) is in contact with the sealing part of the sand core (1).

6. The sand mold for vacuum pump housing casting according to claim 1, characterized in that: The limiting workpiece (3) adopts a limiting nut (31) and a limiting end cap (32); the core bone (2) adopts a steel bar screw, the limiting nut (31) is threadedly connected to the end of the steel bar screw, and the limiting end cap (32) is plugged into the end of the core bone (2) and is tightly fitted with the side of the limiting nut (31) away from the sealing part of the sand core (1).

Images