Sand mold structure for thin-walled castings and casting method

Abstract

The present application relates to a sand mould structure for thin-walled castings, comprising an upper sand mould, a lower sand mould and a cantilevered sand core arranged between the upper and lower sand moulds, wherein a core bone exposed at both ends is arranged in the cantilevered sand core; a sand filling hole is arranged between the exposed end of the core bone of the cantilevered sand core and the lower sand mould, and a wedge is arranged in the sand filling hole, one side of the wedge abutting against the exposed end of the core bone and the other side of the wedge pressing against the lower sand mould. The present application also discloses a casting method using the above-mentioned sand mould structure for thin-walled castings. The sand mould structure for thin-walled castings disclosed by the present application effectively increases the strength and bending resistance of the cantilevered sand core by arranging a core bone exposed at both ends in the cantilevered sand core and wedging the wedge at the exposed end, thereby preventing the cantilevered sand core from floating and deforming during pouring and improving the dimensional accuracy of the thin-walled castings; and the bending resistance of the core bone is further increased by using an arc-shaped core bone opposite to the direction of buoyancy, thereby ensuring the accuracy of the castings without using a clamp.

Description

Technical Field

[0001] This invention relates to the field of casting technology, and in particular to a sand mold structure and casting method for thin-walled castings. Background Technology

[0002] In castings, sand cores are typically used to form the inner cavity of the oil tubing. For large castings such as machine tools and frames, cantilever sand cores with large length, width, and small height are used for the oil tubing. During the pouring process, the buoyancy of the cantilever sand core is greater than that of other types of sand cores. Therefore, cantilever sand cores are prone to drifting and deformation, ultimately leading to large dimensional errors in the cast oil tubing or even through-skin defects. In this field, a standard core is usually used to connect the sand core to the lower sand core to solve the drifting problem; however, this method is not effective for cantilever sand cores. Summary of the Invention

[0003] Therefore, it is necessary to provide a sand mold structure and casting method for thin-walled castings to address the technical problems of cantilever sand cores being prone to core drift and deformation.

[0004] To solve the above problems, the present invention adopts the following technical solution:

[0005] This invention discloses a sand mold structure for thin-walled castings, including an upper sand mold, a lower sand mold, and a cantilevered sand core disposed between the upper and lower sand molds. The cantilevered sand core has a core bone with both ends exposed. A sand filling hole is provided between the exposed end of the core bone of the cantilevered sand core and the lower sand mold. A wedge is provided in the sand filling hole, with one side of the wedge abutting against the exposed part of the core bone and the other side pressing against the lower sand mold.

[0006] In one embodiment, the core is bow-shaped, with the bulging direction opposite to the direction of the buoyancy force exerted on the cantilever sand core by the molten metal.

[0007] In one embodiment, the amount of sand around the core is ≥30mm.

[0008] In one embodiment, the sand mold structure further includes a standard core, which connects the lower sand mold and the cantilever sand core.

[0009] In one embodiment, the standard core includes a first part with a hook section and a second part with a hanging ring section. The end of the first part opposite to the hook section is disposed in the cantilever sand core, and the end of the second part opposite to the hanging ring section is disposed in the lower sand mold. The hook section is hung on the hanging ring section.

[0010] In one embodiment, a protective plate is provided between the wedge and the lower sand mold, and the protective plate is made of metal.

[0011] In one embodiment, the core and / or the wedge is made of metal.

[0012] In one embodiment, the cross-section of the sand-filled hole gradually increases along the direction from the lower sand mold to the upper sand mold.

[0013] Secondly, embodiments of the present invention also disclose a casting method using any of the sand mold structures described above for thin-walled castings, the casting method comprising the following steps:

[0014] Core making involves placing the core in a core box and filling the core box with resin sand to obtain the cantilever sand core.

[0015] Shape and fabricate the upper and lower sand molds;

[0016] The core assembly involves inserting the cantilevered sand core into the cavity of the lower sand mold, placing the wedge into the sand filling hole, and wedging the wedge firmly between the exposed part of the core and the lower sand mold.

[0017] The upper sand mold is assembled with the lower sand mold and the cantilever sand core, and then casting can be carried out.

[0018] Furthermore, positioning elements are provided at both ends of the inner side of the core box. During the core making process, one end of the core rests on one positioning element and the other end rests on another positioning element.

[0019] The technical solution adopted in this invention can achieve the following beneficial effects:

[0020] This invention discloses a sand mold structure for thin-walled castings. By setting core bones with exposed ends and wedges firmly embedded at these exposed ends within the cantilever sand core, the strength and bending resistance of the cantilever sand core are effectively increased, preventing core drift and deformation during pouring, thereby improving the dimensional accuracy of the thin-walled castings. The sand mold structure for thin-walled castings disclosed in this invention employs an arc-shaped core bone with the direction opposite to buoyancy, further increasing the bending resistance of the core bone. The cantilever sand core section does not require clamps to ensure casting dimensional accuracy, effectively reducing costs, improving work efficiency, and eliminating defects such as poor clamp fusion. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view of a sand mold structure for thin-walled castings disclosed in an embodiment of the present invention;

[0022] Figure 2 for Figure 1 A magnified view of part A;

[0023] Figure 3 for Figure 1 A magnified view of part B.

[0024] Explanation of reference numerals in the attached figures:

[0025] 100 - Upper sand mold, 200 - Lower sand mold, 300 - Cantilever sand core, 310 - Core skeleton, 320 - Mounting hole, 410 - First cavity, 420 - Second cavity;

[0026] 500 - Sand filling hole, 511 - First protective plate, 512 - Second protective plate, 521 - First wedge, 522 - Second wedge;

[0027] 610 - Part 1, 620 - Part 2. Detailed Implementation

[0028] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0029] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," "top," "bottom," "end," "top," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0031] This invention discloses a sand mold structure for thin-walled castings, such as... Figures 1 to 3 As shown, the sand mold structure for thin-walled castings disclosed in this embodiment of the invention includes an upper sand mold 100, a lower sand mold 200, and a cantilever sand core 300 disposed between the upper and lower sand molds. The cantilever sand core 300 is disposed within the cavity of the lower sand mold 200, and a first cavity 410 for forming a portion of the thin-walled casting is formed between the lower sand mold 200 and the cantilever sand core 300; the upper sand mold 100 is disposed on the lower sand mold 200, and a second cavity 420 for forming another portion of the thin-walled casting is formed between the upper sand mold 100 and the cantilever sand core 300.

[0032] Specifically, the cantilever sand core 300 forms sand-filling holes 500 on both sides with the cavity sidewalls of the lower sand mold 200. The cantilever sand core 300 also has exposed core bones 310 at both ends to increase its strength and compressive strength. A first wedge 521 and a second wedge 522 are respectively wedged into the sand-filling holes 500 on both sides of the cantilever sand core 300. The first wedge 521 is wedged between one exposed end of the core bone 310 and the cavity sidewall of the lower sand mold 200, and the second wedge 522 is wedged between the other exposed end of the core bone 310 and the cavity sidewall of the lower sand mold 200. This creates a fixing force between the lower sand mold 200, the wedges, and the core bone 310, increasing the strength and bending resistance of the cantilever sand core 300. This effectively prevents the cantilever sand core 300 from floating or deforming due to the buoyancy of the molten metal during casting without the need for clamps.

[0033] In the embodiments disclosed in this invention, the core 310 is arc-shaped, and its bulging direction is opposite to the direction of the buoyancy force exerted on the cantilever sand core 300 by the molten metal during casting, further increasing the bending resistance of the cantilever sand core 300. Preferably, the sand absorption around the core 310 is ≥30mm. The bulging height of the core 310 is preferably 2.0% to 2.5% of the length of the core 310. The core 310 is preferably made of metal, most preferably iron.

[0034] In one optional embodiment of the present invention, such as Figure 3 As shown, one end of the cantilever sand core 300 is fixed between the upper and lower sand molds, its lower side is set in the cavity of the lower sand mold 200, and its upper side is pressed down by the bottom of the upper sand mold 100 to fix it in the cavity of the lower sand mold 200. Figure 2 As shown, the lower side of the other end of the cantilever sand core 300 is set in the cavity of the lower sand mold 200, and its upper side is suspended below the second cavity 420. A standard core can be set here to further fix this end of the cantilever sand core 300 in the cavity of the lower sand mold 200.

[0035] Furthermore, the standard core includes a first part 610 with a hook section and a second part 620 with a hanging ring section. A crossbar is provided at the end of the second part 620 opposite to the hanging ring section, and the crossbar can be pre-fixed within the lower sand mold 200. The cantilever sand core 300 has a through-hole 320, with the larger end of the mounting hole 320 at the top and the smaller end at the bottom. The hanging ring can be hung on the hook. The end of the first part 610 opposite to the hook section passes through the mounting hole 320 from bottom to top and is secured in the larger end of the mounting hole 320 with a fastener. Specifically, a threaded section can be provided at the end of the first part 610 opposite to the hook section, and the fastener can be a nut that matches the threaded section. It should be noted that the circumferential dimension of the fastener should be smaller than the larger end of the mounting hole 320 but larger than the smaller end of the mounting hole 320.

[0036] In the embodiments disclosed in this invention, to prevent the wedge from damaging the lower sand mold 200 and to increase the fixing force between the lower sand mold 200, the wedge, and the core 310, a first protective plate 511 can be provided between the first wedge 521 and the cavity sidewall of the lower sand mold 200 before the first wedge 521 is wedged in. Similarly, a second protective plate 512 can be provided between the second wedge 522 and the cavity sidewall of the lower sand mold 200 before the second wedge 522 is wedged in. The first protective plate 511 and the second protective plate 512 are preferably made of metal, and most preferably iron.

[0037] In the embodiments disclosed in this invention, to facilitate the assembly of the core and the wedge solid core 310, the sand filling hole 500 is preferably slightly shaped, with its cross-section gradually increasing from bottom to top.

[0038] This invention also discloses a casting method using the sand mold structure for thin-walled castings described in any of the above embodiments. Specifically, the casting method includes the following steps:

[0039] Core making: The core 310 is placed in the core box beforehand, and resin sand is filled into the core box to make the cantilever sand core 300.

[0040] Shape and create the upper sand mold 100 and the lower sand mold 200;

[0041] The cantilever sand core 300 is assembled into the cavity of the lower sand mold 200. At this time, sand filling holes 500 are formed between both sides of the cantilever sand core 300 and the side wall of the lower sand mold 200. The first wedge 521 is placed into the sand filling hole 500 on one side and wedged firmly between the exposed part of the core 310 and the lower sand mold 200. The second wedge 522 is placed into the sand filling hole 500 on the other side and wedged firmly between the exposed part of the core 310 and the lower sand mold 200.

[0042] After assembling the mold, fill the sand-filling hole 500 with sand, and then assemble the upper sand mold 100 onto the lower sand mold 200 and the cantilever sand core 300 for casting.

[0043] Furthermore, positioning elements can be provided at both ends of the inner side of the core box. During the core making process, one end of the core 310 rests on one positioning element and the other end rests on another positioning element. After filling with resin sand, a cantilever sand core 300 with both ends of the core 310 exposed can be obtained.

[0044] Of course, if a protective plate is used, it can be placed on the cavity side wall of the lower sand mold 200 before the wedge is inserted into the sand filling hole 500, or it can be placed after the wedge is inserted into the sand filling hole 500 but before it is wedged in.

[0045] It should be noted that if a standard core is used, after connecting the various components of the standard core, sand can be filled and leveled at the exposed part of the standard core.

[0046] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A sand mold structure for thin-walled castings, characterized in that, It includes an upper sand mold, a lower sand mold, and a cantilever sand core disposed between the upper and lower sand molds. The cantilever sand core has a core bone with both ends exposed. A sand filling hole is provided between the exposed end of the core bone of the cantilever sand core and the lower sand mold. A wedge is provided in the sand filling hole. One side of the wedge abuts against the exposed part of the core bone, and the other side presses against the lower sand mold. One end of the cantilever sand core is fixed between the upper and lower sand molds, with its lower side set in the cavity of the lower sand mold and its upper side pressed down by the bottom of the upper sand mold; the upper side of the other end of the cantilever sand core is suspended below the second cavity, and its lower side is set in the cavity of the lower sand mold and a marker core is set thereon, the marker core connecting the lower sand mold and the cantilever sand core. The core is arched, and the direction of its bulge is opposite to the direction of the buoyancy force exerted on the cantilever sand core by the molten metal; the bulge height of the core is 2.0% to 2.5% of the core length.

2. The sand mold structure for thin-walled castings according to claim 1, characterized in that, The amount of sand around the core is ≥30mm.

3. The sand mold structure for thin-walled castings according to claim 1, characterized in that, The standard core includes a first part with a hook section and a second part with a hanging ring section. The end of the first part away from the hook section is located inside the cantilever sand core, and the end of the second part away from the hanging ring section is located inside the lower sand mold. The hook section is hung on the hanging ring section.

4. The sand mold structure for thin-walled castings according to claim 1, characterized in that, A protective plate, made of metal, is provided between the wedge and the lower sand mold.

5. The sand mold structure for thin-walled castings according to claim 1, characterized in that, The core and / or the wedge are made of metal.

6. The sand mold structure for thin-walled castings according to claim 1, characterized in that, The cross-section of the sand-filling hole gradually increases along the direction from the lower sand mold to the upper sand mold.

7. A casting method, characterized in that, Using the sand mold structure for thin-walled castings as described in any one of claims 1 to 6, the casting method comprises the following steps: Core making involves placing the core in a core box and filling the core box with resin sand to obtain the cantilever sand core. Shape and fabricate the upper and lower sand molds; The core assembly involves inserting the cantilevered sand core into the cavity of the lower sand mold, placing the wedge into the sand filling hole, and wedging the wedge firmly between the exposed part of the core and the lower sand mold. The upper sand mold is assembled with the lower sand mold and the cantilever sand core, and then casting can be carried out.

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