A mold assembly and a method for separating a core from a blind cavity deep hole structure casting

Abstract

This invention relates to the field of casting technology, specifically to a mold assembly and core removal method for a blind cavity deep-hole structure casting. The mold assembly for a blind cavity deep-hole structure casting includes a shell unit and a core unit. The shell unit includes a shell body; the shell body has a cavity that conforms to the outer surface contour of the casting; the core unit is located in the cavity; the shape of the core unit matches the inner cavity of the casting; the core unit includes an inner core and an outer core; the outer core covers the surface of the inner core; the collapse strength of the inner core is lower than that of the outer core; the core unit is connected to the shell unit. Through the multi-layer nested structure of the core unit, this helps to solve the problem of high difficulty in core removal for blind cavity deep-hole structure castings.

Description

Technical Field

[0001] This invention relates to the field of casting technology, and more specifically, to a mold assembly and core removal method for a blind cavity deep hole structure casting. Background Technology

[0002] Casting is a process in which metal is heated to a molten state, poured into a pre-prepared mold cavity, and allowed to cool and solidify to obtain a metal casting with a specific shape and size. Casting technology is widely used in machinery manufacturing, the automotive industry, aerospace, and other fields, and can produce metal castings with complex structures. The mold cavity is a hollow space formed by the core and shell. After pouring, the shell needs to be removed, and the core extracted from the casting. Typically, the core material needs to possess a certain mechanical strength to ensure stability during the pouring process. During core removal, because the core itself has a certain strength, it is difficult to break it using mechanical vibration. Therefore, current technology typically uses a chemical immersion method with a core-removing solution, dissolving the core through a chemical reaction and then extracting it from the casting.

[0003] Castings with blind cavities and deep holes refer to castings with internal cavities that have a large depth-to-diameter ratio, narrow channels, and are closed at one end. These structures are typically difficult to achieve through machining and are therefore mostly formed by casting. Due to the unique structure of deep holes, the core-removing fluid needs to soak the core inlet for a long time before it can contact the deep hole and remove itself, resulting in low production efficiency due to the excessive time required. Furthermore, prolonged contact with the core-removing fluid can also cause corrosion of the metal casting, leading to substandard product quality. Summary of the Invention

[0004] To address the challenge of core removal in blind cavity deep hole structure castings, this invention provides a casting mold assembly for blind cavity deep hole structure castings, comprising:

[0005] A shell unit, the shell unit including a shell body; the shell body has a cavity that matches the outer surface contour of the casting;

[0006] A core unit is located in the cavity; the shape of the core unit matches the inner cavity of the casting; the core unit includes an inner core and an outer core; the outer core covers the surface of the inner core; the collapse strength of the inner core is lower than that of the outer core; the core unit is connected to the shell unit.

[0007] Preferably, the region of the outer core furthest from the inner cavity opening of the casting is a region prone to collapse; the wall thickness of the outer core in the region prone to collapse is less than the average wall thickness of the outer core.

[0008] Preferably, the core unit is connected to the shell unit through a support area on the outer core; the wall thickness of the outer core in the support area is greater than the average wall thickness of the outer core.

[0009] Preferably, the extension path of the core unit has a bifurcation region; the wall thickness of the outer core in the bifurcation region is greater than the average wall thickness of the outer core; the support region is located between the bifurcation region and the easily collapsible region.

[0010] Preferably, the extension path of the core unit has an annular path segment and a straight path segment; the connection between the straight path segment and the annular path segment is a bifurcation area; the support area is annular and located on one side of the inner circumference of the annular path segment; the wall thickness of the outer core on the outer circumference of the annular path segment is positively correlated with the cross-section of the core unit.

[0011] Preferably, the wall thickness of the outer core between the bifurcation region and the inner cavity opening of the casting is less than the average wall thickness of the outer core.

[0012] Secondly, the present invention provides a core removal method for a blind cavity deep hole structure casting, the core removal method for the blind cavity deep hole structure casting comprising:

[0013] After the casting assembly of the blind cavity deep hole structure casting is poured, water of the first water pressure is injected into the inner cavity of the casting to impact the inner core of the core unit, and the first water impact time is accumulated.

[0014] Based on the first water hammer duration reaching the preset duration, the hollow outer core is broken;

[0015] Once the outer core has been removed, a second water pressure is injected into the interior of the mold to flush away any residue from the core unit.

[0016] Preferably, the first water pressure is lower than the second water pressure.

[0017] Preferably, the step of breaking the hollow outer core based on the first water hammer duration reaching a preset duration includes:

[0018] Based on the first water hammer duration reaching a preset duration, the casting is controlled to vibrate in order to break the hollow outer core.

[0019] Preferably, the step of breaking the hollow outer core based on the first water hammer duration reaching a preset duration includes:

[0020] Based on the first water hammer duration reaching the preset duration, core-removing liquid is injected into the inner cavity of the casting to break the hollow outer core.

[0021] To address the challenge of core removal in deep-hole blind cavity castings, this invention offers the following advantages:

[0022] By dividing the core unit into an outer core and an inner core, the inner core has a lower collapse strength than the outer core. The inner core is made of a lower-strength material, allowing it to be broken up by high-pressure water during core removal and carried out from the space enclosed by the outer core. The outer core has a hollow structure, thus its structural integrity can be effectively destroyed by either mechanical vibration or immersion in the core-removing solution. Therefore, this invention sets the core unit in a nested structure, using either high-pressure water combined with vibration or high-pressure water combined with core-removing solution dissolution, which improves the core removal efficiency. This reduces the immersion time of the casting in the core-removing solution, decreases the degree of corrosion caused by the solution, and protects product quality. Attached Figure Description

[0023] Figure 1 A schematic diagram of the core unit in the mold assembly of the blind cavity deep hole structure casting of Embodiment 1 is shown;

[0024] Figure 2 It shows Figure 1 A front view of the core unit in the design;

[0025] Figure 3 It shows Figure 2 A schematic diagram of the core unit and wax mold assembly in the diagram;

[0026] Figure 4 A schematic flowchart of the core removal method for the blind cavity deep hole structure casting of Embodiment 2 is shown.

[0027] Figure label:

[0028] 10 Core unit; 11 Inner core; 12 Outer core; 13 Easily collapsible area; 14 Support area; 15 Forking area; 16 Circular path segment; 17 Straight path segment; 20 Wax model. Detailed Implementation

[0029] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, and are not intended to imply any limitation on the scope of the disclosure.

[0030] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment". The terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments and are not intended to limit the indicated devices, elements, or components to having a specific orientation or being constructed and operated in a specific orientation. Furthermore, some of the above terms may be used to indicate other meanings besides orientations or positional relationships; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application according to the specific circumstances. In addition, the terms "installed", "set up", "equipped with", "connected", and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, elements, or components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. Furthermore, the terms "first," "second," etc., are mainly used to distinguish different devices, elements, or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0031] Casting is a process in which metal is heated and melted, poured into a mold cavity consisting of a core and a shell, and then cooled and solidified to obtain a casting. For castings with blind cavities and deep holes, due to the large depth-to-diameter ratio and narrow channels, the traditional core-removing liquid immersion method requires a long time to penetrate from the inlet to contact and dissolve the core. This not only results in low production efficiency but also easily leads to surface corrosion of the casting, affecting product quality.

[0032] To address the challenge of core removal in blind cavity deep hole structure castings, this invention provides a casting mold assembly and a core removal method for blind cavity deep hole structure castings.

[0033] Example 1:

[0034] This embodiment provides a casting mold assembly for a blind cavity deep hole structure casting, such as... Figure 1As shown, a casting mold assembly for a blind cavity deep hole structure casting includes a shell unit and a core unit 10; as Figure 3 As shown, the core unit 10 is mostly enclosed by the wax pattern 20, with only a portion protruding from it. The shape of the wax pattern 20 matches the shape of the casting. After the core unit 10 is made, it is placed in the wax pattern 20. Then, the wax pattern 20 containing the core unit 10 is coated with a slurry by immersion or spraying. After the slurry is applied, it solidifies to form a shell unit, which is not shown in the figure. After removing the wax pattern 20, molten metal can be poured into the cavity between the shell unit and the core unit 10. After the molten metal solidifies, it becomes the casting.

[0035] The shell unit includes a shell body; the shell body has a cavity that matches the outer surface contour of the casting.

[0036] The core unit 10 is located in the cavity; the shape of the core unit 10 matches the inner cavity of the casting; the core unit 10 includes an inner core 11 and an outer core 12; the outer core 12 covers the surface of the inner core 11; the collapse strength of the inner core 11 is lower than the collapse strength of the outer core 12; the core unit 10 is connected to the shell unit.

[0037] The inner core 11 can be made of a lower-strength material, so that when the core is removed, the high-pressure water jet can break it up and carry it out from the space enclosed by the outer core 12. The outer core 12 is stronger than the inner core 11 and will not be broken by the high-pressure water jet. Then, the outer core 12 is soaked in a core-removing solution. Since the inner core 11 in the core unit 10 has been removed, the soaking time required for the remaining outer core 12 is significantly shortened, thereby improving production efficiency. Furthermore, the shortened soaking time reduces the difference between the ideal soaking time and the actual soaking time, thus reducing the degree of corrosion of the casting by the core-removing solution and protecting the product.

[0038] In other embodiments, when the outer core 12 is thin, mechanical vibration can be used to break the outer core 12 and then high-pressure water jet can be used to flush it out, thereby completing the removal of the outer core 12.

[0039] Furthermore, such as Figure 2As shown, the area of ​​the outer core 12 furthest from the inner cavity opening of the casting is the easily collapsible region 13; the wall thickness of the outer core 12 in the easily collapsible region 13 is less than the average wall thickness of the outer core 12. Since the easily collapsible region 13 is furthest from the inner cavity opening of the casting, it is the last and most difficult area of ​​the outer core 12 to fully contact the core-removing liquid during the pouring and soaking process, thus requiring a longer soaking time. By setting the wall thickness of the outer core 12 in the easily collapsible region 13 to be less than the average wall thickness of the outer core 12, the difficulty of breaking the easily collapsible region 13 of the core unit 10 can be reduced, and the soaking time required for the easily collapsible region 13 can be shortened to be consistent with the soaking time required for the entire outer core 12, thereby avoiding a significant difference in the removal effect between the easily collapsible region 13 and the entire outer core 12.

[0040] Furthermore, such as Figure 1 As shown, the core unit 10 is connected to the shell unit through the support area 14 on the outer core 12; the wall thickness of the outer core 12 in the support area 14 is greater than the average wall thickness of the outer core 12. This ensures a stable connection between the outer core 12 and the shell after the shell is formed by applying slurry.

[0041] Furthermore, such as Figure 2 As shown, the extension path of the core unit 10 has a bifurcation region 15; the wall thickness of the outer core 12 in the bifurcation region 15 is greater than the average wall thickness of the outer core 12; the support region 14 is located between the bifurcation region 15 and the easily collapsible region 13. This increases the strength of the outer core 12 corresponding to the bifurcation region 15 to meet the higher strength requirements of the outer core 12 when the flow path of high-pressure water changes abruptly in the bifurcation region 15, while ensuring the structural stability of the bifurcation region 15 of the core unit 10 and improving the casting quality.

[0042] Furthermore, such as Figure 2 As shown, the extension path of the core unit 10 has an annular path segment 16 and a straight path segment 17; the connection between the straight path segment 17 and the annular path segment 16 is a bifurcation region 15; the support region 14 is annular and located on one side of the inner circumference of the annular path segment 16; for castings with a rotary inner cavity, the support region 14 is set in annular shape, which can improve the connection strength between the core unit 10 and the shell unit, thereby adapting to the structural characteristics of the casting assembly with blind holes and deep cavities. The wall thickness of the outer core 12 on the outer circumference side of the annular path segment 16 is positively correlated with the cross-section of the core unit 10. In this way, when the cross-sectional area of ​​the core unit 10 is small, a thinner outer core 12 can be set, so that the high-pressure water can smoothly remove the inner core 11; when the cross-sectional area of ​​the core unit 10 is large, and the high-pressure water flow resistance meets the requirements, a thicker outer core 12 can be set to improve the support strength of the outer core 12.

[0043] In other embodiments, support regions 14 of different shapes can be provided according to the specific extension path of the core unit 10, so that the support region 14 is located between the bifurcation region 15 and the easily diffused region, ensuring the support strength of the core unit 10. The wall thickness of the outer core 12 between the support region 14 and the bifurcation region 15 is positively correlated with the cross-section of the core unit 10. The core between the support region 14 and the bifurcation region 15 is located in the middle of the inner cavity of the casting, with moderate breaking difficulty. Setting the corresponding wall thickness according to the cross-section can balance the overall structural strength of the core unit 10 and the low resistance to high-pressure water flow.

[0044] Furthermore, such as Figure 1 As shown, the wall thickness of the outer core 12 between the bifurcation region 15 and the inner cavity opening of the casting is less than the average wall thickness of the outer core 12. Since the outer core 12 between the bifurcation region 15 and the inner cavity opening of the casting is close to the inner cavity opening of the casting and its shape is similar to a straight pipe, it has little impact on the overall strength of the core unit 10 of the casting with a rotary deep cavity structure. That is, the strength requirement of this section of the outer core 12 is low. Therefore, the thickness of this section of the outer core 12 can be set to be low. This allows for a larger flow rate of high-pressure water after the inner core 11 corresponding to this section of the outer core 12 is removed. This allows for the removal of the remaining inner core 11 at a higher flow rate after the diameter of the extension path is reduced.

[0045] Example 2:

[0046] This embodiment provides a method for core removal in a blind cavity deep hole structure casting, such as... Figure 4 As shown, a method for core removal from a blind cavity deep hole structure casting includes steps S10-S30, which are explained in detail below:

[0047] Step S10: The casting assembly of the casting based on the blind cavity deep hole structure is completed. Water of the first water pressure is injected into the inner cavity of the casting to impact the inner core 11 of the core unit 10, and the first water impact time is accumulated.

[0048] Step S20: Based on the first water hammer duration reaching the preset duration, the hollow outer core 12 is broken;

[0049] Step S30: After the outer core 12 is broken, a second water pressure is injected into the mold to flush away any residue from the core unit 10. This allows for the removal of the core unit 10 by first removing the inner core 11, then removing the outer core 12, and flushing away any remaining core material. By dividing the core unit 10 into the outer core 12 and the inner core 11, the time required to remove the core unit 10 is significantly shortened, improving production efficiency.

[0050] Furthermore, the first water pressure is lower than the second water pressure. The lower first water pressure is sufficient to gradually remove the inner core 11 to form a cavity, allowing the inner core 11 to be discharged in an orderly manner after disintegration. The higher second water pressure provides a good rinsing effect on the remaining core units 10.

[0051] In some other embodiments, step S10 includes steps S11 and S12;

[0052] Step S11: The casting assembly based on the blind cavity deep hole structure casting is poured and the casting is controlled to vibrate to break the outer core 12.

[0053] Step S12: Based on the target duration of the casting under vibration conditions, water of the first water pressure is injected into the inner cavity of the casting to impact the inner core 11 of the core unit 10, and the first water impact duration is accumulated.

[0054] Since the casting is first vibrated in step S11 to destroy the structural integrity of the outer core 12, there is a possibility that the outer core 12 will break. The lower first water pressure can drive the broken outer core 12 to flow out of the inner cavity of the casting in an orderly manner along with the disintegrated inner core 11, avoiding the formation of strong turbulence by the larger water pressure, which would cause the fragments of the outer core 12 to roll back and forth in the inner cavity of the casting. Thus, the water pressure gradient setting of the present invention can improve the core removal efficiency.

[0055] Further, step S20 includes step S21.

[0056] Step S21: Based on the first water hammer duration reaching the preset duration, the casting is controlled to vibrate to break the hollow outer core 12. This allows the outer core 12 to be broken through mechanical vibration of the casting, thus facilitating its removal.

[0057] Further, step S20 includes step S22.

[0058] Step S22: Based on the first water hammer duration reaching the preset time, a core-removing liquid is injected into the inner cavity of the casting to break the hollow outer core 12. This allows the outer core 12 to be removed by a chemical reaction between the core and the liquid.

[0059] It should be understood that during the execution of step S20, at least one of steps S21 and S22 may be performed. Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes in form and detail may be made without departing from the scope of this disclosure.

Claims

1. A casting mold assembly for a blind cavity deep hole structure casting, characterized in that, The casting mold assembly of the blind cavity deep hole structure casting includes: A shell unit, the shell unit including a shell body; the shell body has a cavity that matches the outer surface contour of the casting; A core unit is located within the mold cavity; the shape of the core unit matches the inner cavity of the casting; the core unit includes an inner core and an outer core; the outer core covers the surface of the inner core; the collapse strength of the inner core is lower than that of the outer core; the core unit is connected to the shell unit. The region of the outer core furthest from the inner cavity opening of the casting is a region prone to collapse; the wall thickness of the outer core in the region prone to collapse is less than the average wall thickness of the outer core; The extension path of the core unit has a bifurcation region; the extension path of the core unit has an annular path segment and a straight path segment; the junction of the straight path segment and the annular path segment is the bifurcation region; the wall thickness of the outer core on the outer circumference side of the annular path segment is positively correlated with the cross-section of the core unit.

2. The casting mold assembly for a blind cavity deep hole structure casting according to claim 1, characterized in that, The core unit is connected to the shell unit through a support area on the outer core; the wall thickness of the outer core in the support area is greater than the average wall thickness of the outer core.

3. The casting mold assembly for a blind cavity deep hole structure casting according to claim 2, characterized in that, The wall thickness of the outer core in the bifurcation region is greater than the average wall thickness of the outer core; the support region is located between the bifurcation region and the easily collapsible region.

4. The casting mold assembly for a blind cavity deep hole structure casting according to claim 3, characterized in that, The support area is annular and located on one side of the inner circle of the annular path segment.

5. The casting mold assembly for a blind cavity deep hole structure casting according to claim 3, characterized in that, The wall thickness of the outer core between the bifurcation region and the inner cavity opening of the casting is less than the average wall thickness of the outer core.

6. A core removal method for a blind cavity deep hole structure casting, applied to the mold assembly of the blind cavity deep hole structure casting according to any one of claims 1-5; characterized in that, The core removal method for the blind cavity deep hole structure casting includes: After the casting assembly of the blind cavity deep hole structure casting is poured, water of the first water pressure is injected into the inner cavity of the casting to impact the inner core of the core unit, and the first water impact time is accumulated. Based on the first water hammer duration reaching the preset duration, the hollow outer core is broken; Once the outer core has been broken down, a second water pressure is injected into the interior of the mold to flush away any residue from the core unit. The first water pressure is less than the second water pressure.

7. The method for core removal of a blind cavity deep hole structure casting according to claim 6, characterized in that, The step of breaking the hollow outer core based on the first water hammer duration reaching a preset duration includes: Based on the first water hammer duration reaching a preset duration, the casting is controlled to vibrate in order to break the hollow outer core.

8. The method for core removal of a blind cavity deep hole structure casting according to claim 6, characterized in that, The step of breaking the hollow outer core based on the first water hammer duration reaching a preset duration includes: Based on the first water hammer duration reaching the preset duration, core-removing liquid is injected into the inner cavity of the casting to break the hollow outer core.

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