Modular composite sand mold structure for hammer head casting

Abstract

The utility model discloses a modularization composite sand mould structure for hammer head casting. The sand mould structure includes the upper box body and lower box body of buckling connection, the upper box body and lower box body buckling form the cavity corresponding with the hammer head shape together in the inside, the preset inner wall of cavity is provided with modularization refractory inner lining, the modularization refractory inner lining is combined by at least two refractory modules through splicing structure, the back of refractory module is provided with anchoring structure, and the working surface of modularization refractory inner lining covers a layer of functional coating. The structure avoids that the high temperature metal liquid erodes the sand mould when casting, also can not infiltrate the joint, thereby thoroughly avoids the surface defects such as sand sticking, sand eye, sand inclusion, blowhole and the like caused by the sand mould being washed out or the metal liquid infiltrating, and the quality of casting surface quality is improved.

Description

Technical Field

[0001] This utility model belongs to the field of metal casting technology, and in particular relates to a modular composite sand mold structure for hammer casting. Background Technology

[0002] A rock drilling hammer is made of two parts: a hammer body and a hammer head. Currently, the hammer head is mainly formed by sand casting of high manganese steel.

[0003] High-manganese steel is an alloy steel with a manganese content exceeding 10%. Due to its unique work hardening characteristics and excellent wear resistance, it is widely used in mining, railways, and machinery manufacturing. The main components of high-manganese steel are carbon (0.9%-1.5%) and manganese (10%-15%), with the manganese content determining its core properties. Through water quenching (heating to 1050-1100℃ followed by water quenching), a single-phase austenitic structure (i.e., austenitic manganese steel) can be formed, combining high toughness with work hardening capability.

[0004] Austenitic manganese steel is characterized by impact resistance, wear resistance, and good toughness. Its elongation reaches 35%-40%, and its impact strength at -20℃ can reach 100-200J. At room temperature, its Brinell hardness is no higher than 300HBW. However, under high pressure or high impact load, it has the ability to work harden and undergoes an austenitic-martensite transformation. The maximum surface hardness can increase from 210HB to 600HB, and it hardly affects the toughness, thereby greatly improving the service life of wear-resistant parts.

[0005] High-manganese steel possesses the aforementioned properties, making it suitable as a material for hammerheads to meet relevant application requirements. However, in the sand casting process of hammerheads, due to the triangular cross-section of the hammerhead, a bottom-return gating system is typically used to facilitate the placement of the inner gate and ensure stable filling. In this system, the inner gate is located at the bottom of the casting, resulting in stable molten metal filling, minimal impact on the mold and core, and facilitating gas escape from the mold cavity. However, the high temperature at the bottom of the casting during pouring and the initial solidification phase hinders feeding, easily leading to shrinkage cavities and porosity defects within the casting. These defects can severely negatively impact the hammerhead during harsh use, potentially causing breakage or a significant reduction in service life. Furthermore, this casting method consumes a large amount of molten metal, resulting in high production costs. Therefore, improvements to this casting method are necessary.

[0006] Since it is inconvenient to place the inner gate on the beveled side of the hammerhead, the inner gate can be placed on the flat surface of the side of the hammerhead, that is, a side-entry gating system is adopted. In this way, the inner gate is located on the upper side of the casting, and the molten metal flows into the mold cavity from the upper side of the casting, which is easy to fill and facilitates the formation of a bottom-up solidification sequence in the casting. The feeding effect is good, which can effectively reduce the risk of shrinkage cavities and porosity inside the casting. Moreover, the gating system is simple and consumes less molten metal. However, the disadvantage is that the scouring force on the sand mold (the beveled part of the casting) is large, and the molten metal is prone to splashing and oxidation, which will cause casting defects such as sand holes, air holes, iron beads, and oxide slag.

[0007] To prevent the aforementioned casting defects, further measures are required. Utility Model Content

[0008] Based on the above analysis, this utility model aims to provide a modular composite sand mold structure for hammer casting, which solves at least the following technical problems: the existing side-entry pouring method is prone to erosion of the mold cavity, resulting in defects such as sand holes and air holes on the surface of the casting.

[0009] The objective of this utility model is mainly achieved through the following technical solutions:

[0010] A modular composite sand mold structure for hammerhead casting includes an upper box 1a and a lower box 1b that can be snapped together. When the upper box 1a and the lower box 1b are snapped together, they together form a cavity corresponding to the shape of the hammerhead. The pre-set inner wall of the cavity is provided with a modular refractory lining 2. The modular refractory lining 2 is composed of at least two refractory modules 201 assembled by splicing. An anchoring structure is provided on the back of the refractory module 201. The working surface of the modular refractory lining 2 is covered with a functional coating 3.

[0011] Furthermore, the splicing structure is a mortise and tenon structure or a convex-concave mating structure.

[0012] Furthermore, the anchoring structure is a dovetail groove, T-groove, inverted conical protrusion, or blind hole array formed on the back of the fire-resistant module 201.

[0013] Furthermore, the blind hole array includes a plurality of irregularly shaped holes formed in the fire-resistant module 201, the cross-section of which is circular, square or cross-shaped.

[0014] Furthermore, the functional coating 3 covers the working surface of the fire-resistant module 201 and the seams of the splicing structure.

[0015] Furthermore, the fire-resistant module 201 has a flat, trapezoidal, or wedge-shaped outline.

[0016] Furthermore, the upper housing 1a is also provided with a riser 4 that communicates with the cavity, and the riser 4 is used to feed the casting.

[0017] Furthermore, the pre-designed inner wall of the cavity is an inclined surface opposite to the hammer impact working surface.

[0018] Furthermore, the sand mold structure is also provided with a gating system 5 that communicates with the mold cavity. The gating system 5 includes a sprue, a runner, and an ingate. The outlet of the ingate is located on the upper box 1a and communicates with the upper side of the mold cavity.

[0019] Furthermore, the components of the casting system 5 are prefabricated as ceramic pipes and embedded in the upper housing 1a and / or lower housing 1b.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0021] (1) In this utility model, the modular refractory lining itself has a much higher fire resistance and erosion resistance than resin sand, forming a first solid line of defense against the erosion of molten metal. The functional coating covering it serves as a second line of defense. The synergistic effect of these two ensures that the high-temperature molten metal cannot erode the sand mold or penetrate into the joints, thereby completely avoiding surface defects such as sand sticking, sand holes, sand inclusions, and air holes caused by the destruction of the molding sand or the penetration of molten metal. The surface quality of the casting is qualitatively improved.

[0022] (2) The dovetail groove, T-groove or cross-shaped blind hole array pre-set on the back of the refractory module of this utility model is filled and hardened by flowing resin sand during molding, which firmly anchors the refractory module from the back, effectively resists the buoyancy of the molten metal and the scouring force on the front, prevents the modular refractory lining from falling off or floating in whole or in part, ensures the safety and stability of the casting process, and avoids scrap caused by lining displacement.

[0023] (3) In this utility model, individual refractory modules can be designed with different contours (such as trapezoids or wedges) according to the complex curved or inclined surfaces of the cavity. They can be fitted together through flexible splicing and combination. The specific splicing structure ensures the assembly accuracy, so that the sand mold structure can be applied to hammers of different specifications and shapes, as well as other complex castings, which greatly improves its versatility. Moreover, in actual production, if the refractory lining of a certain part of the cavity is damaged, it is not necessary to scrap the entire sand mold or carry out complex repairs. Only the damaged individual or several modules need to be replaced, which significantly reduces maintenance and production costs.

[0024] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0025] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0026] Figure 1 This is a schematic diagram of the modular composite sand mold structure of this utility model.

[0027] Figure label:

[0028] 1a. Upper box; 1b. Lower box; 2. Modular refractory lining; 201. Refractory module; 3. Functional coating; 4. Riser; 5. Casting system. Detailed Implementation

[0029] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0030] This utility model provides a modular composite sand mold structure for hammerhead casting, including an upper box 1a and a lower box 1b that can be snapped together. After the upper box 1a and the lower box 1b are snapped together, they together form a cavity corresponding to the shape of the hammerhead. The pre-set inner wall of the cavity is provided with a modular refractory lining 2. The modular refractory lining 2 is composed of at least two refractory modules 201 assembled by splicing. The back of the refractory module 201 is provided with an anchoring structure. The working surface of the modular refractory lining 2 is covered with a functional coating 3.

[0031] In this invention, the modular refractory lining 2 solves the damage to castings caused by traditional side-injection casting methods, such as casting defects like sand holes, porosity, iron filings, and oxide slag. Simultaneously, modular splicing allows for flexible combination and can conform to the complex curved surfaces of various hammerhead cavities, ensuring comprehensive protection. In actual production, if a portion of the refractory lining in a cavity is damaged, there is no need to scrap the entire sand mold or perform complex repairs; only the damaged single or several modules need to be replaced, significantly reducing maintenance and production costs.

[0032] Furthermore, when the resin sand fills and wraps the anchoring structure during the molding process, it forms a strong mechanical interlocking force, which greatly enhances the stability of the refractory module 201 in the sand mold, effectively resists the scouring force and buoyancy of the high-temperature molten metal, prevents it from shifting or falling off, and ensures the safety and reliability of the casting process.

[0033] According to this utility model, in order to ensure accurate positioning and tight connection between the fire-resistant modules 201, the splicing structure is a mortise and tenon structure or a concave-convex fit structure, which can effectively suppress the expansion of the joint when heated or stressed, thereby preventing molten metal from seeping in from the joint and ensuring the integrity and continuity of protection of the modular lining.

[0034] According to this invention, the anchoring structure is a dovetail groove, T-groove, inverted conical protrusion, or blind hole array formed on the back of the refractory module 201. This structure effectively increases the contact area and locking force between the resin sand and the refractory module 201, ensuring the anchoring effect.

[0035] According to this utility model, the blind hole array includes a plurality of irregular holes formed in the fire-resistant module 201, and the cross-section of the irregular holes is circular, square or cross-shaped.

[0036] It should be noted that irregularly shaped holes provide stronger resistance to torsion and shear. When resin sand fills these irregularly shaped holes and hardens, the resulting anchors are more difficult to pull out or shear, further enhancing the strength and reliability of the anchoring.

[0037] According to this utility model, the functional coating 3 covers the working surface of the fire-resistant module 201 and the joints of the splicing structure.

[0038] In this invention, the functional coating 3 serves to seal and reinforce the surface. It fills the micropores and seams on the surface of the refractory module 201, forming a smoother, denser, and inert barrier. This further prevents the penetration of molten metal and sand adhesion, contributing to a smooth-surfaced casting. Together with the modular refractory lining, it provides dual protection, further enhancing resistance to damage from molten metal splashing and erosion.

[0039] For example, in this invention, the functional coating 3 is formed by applying an alcohol-based zircon powder coating.

[0040] According to this utility model, in order to better adapt to the inner wall contour of the cavity and improve the practicality and fit of the modular design, the contour of the fire-resistant module 201 is flat, trapezoidal or wedge-shaped.

[0041] According to this utility model, in order to eliminate defects such as shrinkage cavities and porosity inside the casting, the upper box 1a is also provided with a riser 4 that communicates with the cavity, and the riser 4 is used to feed the casting.

[0042] According to this utility model, the preset inner wall of the cavity is an inclined surface opposite to the impact working surface of the hammer.

[0043] It should be noted that in hammer casting, the inclined surface directly faces the direction of molten metal flow, making it the area most severely affected by erosion. Installing a modular refractory liner 2 at this location can more effectively address casting defects caused by molten metal splashing.

[0044] According to this utility model, the sand mold structure is further provided with a gating system 5 communicating with the mold cavity. The gating system 5 includes a sprue, a gating runner and an ingate. The outlet of the ingate is located on the upper box 1a and communicates with the upper side of the mold cavity.

[0045] According to this utility model, the casting system 5 is prefabricated into ceramic pipes and embedded in the upper box 1a and / or lower box 1b. The ceramic pipes of the casting system 5 are pre-embedded in the resin sand of the upper box 1a and / or lower box 1b during molding, avoiding sand scouring and shedding problems that may occur if the gating channel is directly excavated in the sand mold. This further ensures the purity and stability of the casting process and, together with the modular refractory lining 2, improves the quality of the casting.

[0046] Figure 1 This is a schematic diagram of the modular composite sand mold structure provided by this utility model. Figure 1 The arrangement of the upper box 1a, lower box 1b, modular refractory lining 2, functional coating 3, riser 4 and gating system 5 is shown. The following details the fabrication and use of this composite sand mold structure.

[0047] Prepare a modular refractory liner 2 that matches the profile of the cavity slope. This liner consists of three wedge-shaped refractory modules 201 (mainly composed of Al2O3), which can be assembled using a mortise and tenon joint structure. Each refractory module 201 has multiple pre-fabricated blind hole arrays with cross-shaped cross sections on its back as an anchoring structure.

[0048] The mold of the lower box 1b is placed on the molding plate. The assembled modular refractory lining 2 is then placed on the preset inclined surface of the cavity of the lower box 1b, making its working surface flush with the cavity surface. Resin sand is then filled and compacted. The resin sand will fully flow into and fill the cross-shaped blind holes on the back of the refractory module, forming a strong mechanical anchor after hardening. During the molding process of the upper box 1a, the pre-made gating system 5 consisting of ceramic sprues, runners, and ingates, as well as the model of the insulating riser 4, are placed in place beforehand, and then resin sand is filled and compacted. The working surface and joints of the exposed modular refractory lining 2 in the cavity of the lower box 1b are evenly coated or sprayed with alcohol-based zircon powder coating, which forms a dense functional coating 3 after curing, resulting in a modular composite sand mold structure.

[0049] The assembled sand mold is transported to the casting area. High-manganese steel molten metal is smoothly poured into the gating system 5 through the sprue. The molten metal flows into the upper side of the cavity through the runner and ingate, directly impacting the inclined surface protected by the modular refractory lining 2.

[0050] Due to the extremely high refractoriness and erosion resistance of the modular refractory lining 2 and its surface functional coating 3, the molten metal failed to erode the surface or penetrate the joints. The anchoring structure on the back effectively resisted the buoyancy and erosion force of the molten metal, ensuring the stability of the lining. After pouring, the molten metal solidified in the mold cavity, and the riser 4 effectively fed the casting, avoiding the generation of shrinkage cavities and porosity defects.

[0051] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A modular composite sand mold structure for hammerhead casting, characterized in that, It includes an upper box (1a) and a lower box (1b) that can be snapped together. After the upper box (1a) and the lower box (1b) are snapped together, they together form a cavity corresponding to the shape of a hammer. The inner wall of the cavity is provided with a modular fire-resistant lining (2). The modular fire-resistant lining (2) is composed of at least two fire-resistant modules (201) assembled by splicing structure. The back of the fire-resistant module (201) is provided with an anchoring structure. The working surface of the modular fire-resistant lining (2) is covered with a functional coating (3).

2. The sand mold structure according to claim 1, characterized in that, The splicing structure is a mortise and tenon structure or a concave-convex fit structure.

3. The sand mold structure according to claim 1, characterized in that, The anchoring structure is a dovetail groove, T-groove, inverted conical protrusion or blind hole array formed on the back of the fire-resistant module (201).

4. The sand mold structure according to claim 3, characterized in that, The blind hole array includes multiple irregular holes formed in the fire-resistant module (201), and the cross-section of the irregular holes is circular, square or cross-shaped.

5. The sand mold structure according to claim 1, characterized in that, The functional coating (3) covers the working surface of the fire-resistant module (201) and the joints of the splicing structure.

6. The sand mold structure according to claim 1, characterized in that, The fire-resistant module (201) has a flat, trapezoidal, or wedge-shaped outline.

7. The sand mold structure according to claim 1, characterized in that, The upper housing (1a) is also provided with a riser (4) that communicates with the cavity, and the riser (4) is used to feed the casting.

8. The sand mold structure according to claim 1, characterized in that, The pre-designed inner wall of the cavity is an inclined surface opposite to the impact working surface of the hammer.

9. The sand mold structure according to claim 1, characterized in that, The sand mold structure is also provided with a gating system (5) that communicates with the cavity. The gating system (5) includes a sprue, a gating runner and an ingate. The outlet of the ingate is located on the upper box body (1a) and communicates with the upper side of the cavity.

10. The sand mold structure according to claim 9, characterized in that, The components of the casting system (5) are prefabricated as ceramic pipes and embedded in the upper box (1a) and / or lower box (1b).

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