Method of compression molding of a cast wax pattern and cold wax structure and mold tooling therefor

Abstract

The application provides a pressing forming method of a casting wax mold and a cold wax structure and a mold tool used in the method, the cold wax structure for the casting wax mold comprises a cold wax body, a flow guide opening and a positioning part arranged on the cold wax body; the flow guide opening is arranged at the edge of the cold wax body; the positioning part comprises a positioning hole arranged on the lower surface of the cold wax body and / or penetrating through the upper and lower surfaces of the cold wax body, and the positioning hole is arranged so that the cold wax structure is accurately positioned in the casting wax mold, and most importantly, the arrangement of the flow guide opening enables the wax liquid to be diffused and branched at the flow guide opening and evenly coated on the cold wax body, thereby solving the problem that the cold wax structure is deviated due to the single-sided pressure formed by the wax injection pressure impact.

Description

Technical Field

[0001] This invention relates to the field of investment casting mold technology, specifically to a method for pressing and forming a wax pattern for castings, and a cold wax structure and mold tooling for using it. Background Technology

[0002] Dimensional control in investment casting primarily involves two stages: wax pattern pressing and melting / pouring. In the wax pattern pressing process, placing cold wax in thicker areas of the product to reduce wax pattern deformation is a common technique. Placing cold wax can homogenize the wall thickness and temperature of wax patterns of varying thicknesses, resulting in a stable wax flow rate, reduced turbulence, and consistent shrinkage across different locations, thus minimizing deformation. However, the cold wax is affected by the impact pressure of the wax filling in the main mold, causing displacement and swaying. This makes it impossible to ensure that the cold wax remains stably positioned throughout the entire wax pouring process, leading to large areas of exposed or incomplete filling of the wax pattern after molding. This necessitates extensive manual repairs, reduces the surface quality of the wax pattern, and interferes with its dimensional accuracy.

[0003] Currently, the common method for positioning cold wax is to design spherical or conical wax protrusions on the cold wax model. This gives the cold wax positioning protrusions, allowing it to be clamped and positioned within the main wax model mold. However, only three protrusions on the cold wax can restrict the degree of freedom in one direction. For non-planar, irregularly shaped, large-sized cold wax, multiple protrusions are needed for positioning. Moreover, this method of positioning by having the cold wax protrusions press against the mold cavity sidewalls within the main wax model mold is prone to breakage due to the low strength of the protrusion tips during installation. Even if the installation is stable, the cold wax protrusions cannot withstand the high pressure of wax injection and are crushed, thus failing to solve the practical problem. Summary of the Invention

[0004] To address the problems existing in the prior art, the main objective of this invention is to provide a method for pressing and forming a wax mold for castings, as well as a cold wax structure and mold tooling for it. The cold wax structure for casting wax molds accurately positions itself in the casting wax mold by setting positioning components on the cold wax body. Most importantly, the setting of the outlet enables the wax liquid to diffuse and distribute at the outlet and evenly coat the cold wax body, thereby solving the problem of the cold wax structure shifting due to the single-sided pressure formed by the wax injection pressure impact.

[0005] To achieve the above objectives, according to a first aspect of the present invention, a cold wax structure for casting wax molds is provided.

[0006] The cold wax structure for casting wax molds includes a cold wax body and a flow port and positioning components disposed on the cold wax body;

[0007] The drainage port is located at the edge of the cold wax body;

[0008] The positioning component includes a positioning hole, which is disposed on the lower surface of the cold wax body and / or extends through the upper and lower surfaces of the cold wax body.

[0009] Furthermore, the drainage port is a notch or groove opened at the edge of the cold wax body;

[0010] Preferably, the drainage port is rectangular or hemispherical in shape.

[0011] Furthermore, the positioning component also includes a positioning protrusion disposed on the upper surface of the cold wax body.

[0012] Furthermore, the positioning protrusion is hemispherical;

[0013] Preferably, the diameter of the positioning hole is 2.8 to 3.5 mm.

[0014] To achieve the above objectives, according to a first aspect of the present invention, a mold tooling for casting wax patterns is provided.

[0015] The mold tooling for casting wax patterns includes a casting wax pattern mold and the aforementioned cold wax structure; wherein,

[0016] The casting wax mold has the same outline shape as the cold wax body, and the size of the cold wax body is smaller than the size of the casting wax mold;

[0017] The casting wax mold includes an upper mold body and a lower mold body that are interlocked, and the two together form a cavity; the cold wax structure is detachably placed inside the cavity;

[0018] The lower mold body is provided with a positioning column, which is positioned and engaged with the positioning hole.

[0019] Furthermore, the positioning column includes a limiting frustum and a connecting cylinder that are fixedly connected, and the connecting cylinder is inserted into the positioning hole.

[0020] Furthermore, there are gaps between the upper surface, lower surface, and side surface of the cold wax body and the cavity wall of the casting wax mold.

[0021] To achieve the above objectives, according to a first aspect of the present invention, a method for pressing and forming a wax pattern for casting is provided.

[0022] The pressing and forming method for the wax model of the casting is based on the above-mentioned mold tooling; the pressing and forming method includes the following steps:

[0023] Fabrication of cold wax structures;

[0024] The cold wax structure is placed in the cavity through the positioning hole and the positioning column; wherein, the drain port is set directly opposite the wax injection nozzle of the casting wax mold; there are gaps of the same distance between the upper surface, lower surface and side of the cold wax body and the cavity wall of the casting wax mold;

[0025] Molten wax is injected into the cavity of the casting wax mold through the wax injection nozzle. The molten wax diffuses and flows at the outlet and evenly coats the upper surface, lower surface and side surface of the cold wax body until the gap is filled.

[0026] After wax injection is completed, a casting wax model containing the cold wax structure is obtained, and then the casting wax model is removed from the cavity of the casting wax model mold.

[0027] Furthermore, the cold wax structure is made using a wax mold pressing process. After the cold wax structure is demolded, it is cooled for a certain period of time to shrink to the designed size; wherein, the shrinkage rate of the cold wax structure is 0.4-0.8%.

[0028] Furthermore, the casting wax model is ejected from the cavity of the casting wax model mold using pneumatic or mechanical ejection methods;

[0029] Preferably, the gap is 3-5 mm;

[0030] The longitudinal cross-sectional area at the inlet of the drainage port is not less than twice the longitudinal cross-sectional area of ​​the wax injection nozzle.

[0031] This invention primarily provides a novel cold wax structure design. In the wax injection pressing process of casting wax molds, the inlet of this cold wax structure needs to be directly opposite the wax injection nozzle of the mold. This allows the wax liquid to diffuse and distribute at the inlet, uniformly coating the cold wax body. This solves the problem of cold wax structure displacement caused by one-sided pressure due to wax injection pressure impact, ensuring the cold wax structure is stably positioned in the predetermined position throughout the wax injection process. It significantly reduces the number of exposed positioning protrusions in the cold wax structure, and also significantly reduces the amount of manual repair required on the surface of the casting wax mold, eliminating the need to repair cold wax protrusions, thus improving the surface quality of the casting wax mold and increasing production efficiency.

[0032] In addition, because the gap between the cold wax structure and the cavity wall of the casting wax mold is uniform and the spacing is the same, the dimensional control accuracy of the casting wax mold is high.

[0033] In addition, by using pneumatic or mechanical ejection methods, the wax mold of the casting is stable when ejected, and there is no breakage of the positioning holes in the cold wax structure. Attached Figure Description

[0034] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0035] Figure 1 This is a schematic diagram of the structure of the casting wax model in the embodiment provided by the present invention;

[0036] Figure 2 This is a top view of the combination of the lower mold and the cold wax structure in an embodiment of the present invention;

[0037] Figure 3 for Figure 2 Cross-sectional view along the HH direction;

[0038] Figure 4 A top view of the lower mold body and cold wax structure of the casting wax mold provided in the embodiment of the present invention;

[0039] Figure 5 for Figure 4 Cross-sectional view in the JJ direction.

[0040] In the picture:

[0041] 1. Cold wax body; 2. Drain port; 3. Positioning hole; 4. Positioning protrusion; 5. Lower mold body; 6. Lower mold of cold wax mold; 7. Positioning column; 8. Gap; 9. Wax injection nozzle; 10. Casting wax model. Detailed Implementation

[0042] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0043] Because the cold wax structure is affected by the impact pressure of wax filling in the casting wax mold, displacement and wobble will occur, resulting in large areas of cold wax being exposed or insufficient wax filling after the casting wax mold 10 is formed. This reduces the surface quality of the casting wax mold 10 and interferes with its dimensions. The traditional solution is to use cold wax protrusions to press against the side wall of the mold cavity for positioning in the casting wax mold. However, because the tip strength of the cold wax protrusions is low, they are easily bumped and crushed during installation. Even if they are stable during installation, the cold wax protrusions cannot withstand the high pressure of wax injection and will be crushed, which cannot effectively solve the displacement and wobble problems.

[0044] Although some have proposed using positioning pins to fix the cold wax structure in the casting wax mold, in actual production operations, defects or problems still occur, such as the cold wax structure being impacted by the wax injection pressure in the casting wax mold, resulting in one-sided pressure and causing the cold wax to shift. It is impossible to guarantee that the cold wax structure is stably centered in the casting wax mold, and the cold wax positioning hole often breaks after the casting wax mold is demolded.

[0045] Therefore, the present invention provides a cold wax structure for casting wax molds. The cold wax structure has a drain port 2 at the edge of its cold wax body 1. The wax liquid will diffuse and flow at the drain port 2 and evenly cover the upper surface, lower surface and side surface of the cold wax body 1, thereby avoiding the problem of single-sided pressure caused by wax injection pressure impact, which would cause the cold wax structure to shift.

[0046] It should be noted that, in order to better illustrate the cold wax structure in the embodiments of the present invention, Figure 3 as well as Figure 5 The cross-sectional diagram shown uses a format where one side is filled and the other side is blank, for reference and understanding.

[0047] See Figures 1-5 As shown, the cold wax structure for casting wax molds includes a cold wax body 1, a flow port 2 and a positioning component disposed on the cold wax body 1; wherein, the flow port 2 is opened at the edge of the cold wax body 1; specifically, the flow port 2 can be a notch or groove opened at the edge of the cold wax body 1, the notch or groove structure is relatively simple and easy to manufacture; the positioning component includes a positioning hole 3, which is disposed on the lower surface of the cold wax body 1 and / or through the upper and lower surfaces of the cold wax body 1, and the specific structure of the positioning hole 3 can be designed according to actual needs.

[0048] In an embodiment of the present invention, when the casting wax mold 10 is prepared by the wax injection pressing process, the cold wax structure is installed on the lower mold body 5 of the casting wax mold through the positioning hole 3 and positioned at a predetermined position. At this time, the outlet 2 is set directly opposite the wax injection nozzle 9 of the casting wax mold. Since the outlet 2 can diffuse and evenly distribute the wax liquid at the outlet 2, it can avoid the occurrence of single-sided pressure caused by the wax injection pressure impact, thus ensuring that the cold wax structure is stably positioned in the preset position without displacement during the entire wax injection process.

[0049] In some embodiments of the present invention, the shape of the drainage port 2 can be cuboid or hemispherical, with a uniform and symmetrical structure. Of course, in actual production operations, the design can be adjusted according to the actual structure of the casting wax model, and no specific limitation is made.

[0050] In some embodiments of the present invention, the diameter of the positioning hole 3 is 2.8 to 3.5 mm, and the diameter of the positioning hole 3 can be designed according to actual needs.

[0051] In some embodiments of the present invention, the positioning component further includes a positioning protrusion 4, which is disposed on the upper surface of the cold wax body 1. During wax injection and pressing, the upper surface of the cold wax body 1 is close to the upper mold body of the casting wax mold.

[0052] like Figure 3 As shown, no more than three positioning protrusions 4 are designed on the side of the cold wax body 1 opposite to the positioning hole 3. The positioning protrusions 4 can be hemispherical, and the radius of the sphere is consistent with the wall thickness of the thin-walled area of ​​the casting wax model 10. Then, by setting gaps with the same spacing between the cold wax structure and the cavity wall of the casting wax model mold, a casting wax model 10 with a uniform wall thickness is finally formed. On the other hand, the setting of the positioning protrusions 4 also limits the movement of the cold wax structure along the axial direction of the positioning hole 3.

[0053] It is worth mentioning that the specific shape of the positioning protrusion 4 can be designed according to the actual desired structure of the casting wax model 10. The hemispherical shape is only one specific embodiment of the present invention and is not specifically limited thereto.

[0054] See Figure 2 and Figure 3 As shown, the cold wax structure is made by wax mold pressing process. Three relatively evenly distributed support positions are selected on the lower mold 6 of the cold wax mold. Three positioning columns 7 are designed along the mold exit direction of the cold wax structure. After the cold wax is pressed, three corresponding positioning holes 3 are formed on the cold wax body 1, which serve as the installation holes of the cold wax structure in the casting wax mold. The three positioning holes 3 limit the movement of the cold wax structure along the direction perpendicular to the hole diameter.

[0055] In an embodiment of the present invention, the positioning post 7 can be a stepped pin with a diameter of 2-4 mm and a step height of 5 mm.

[0056] According to a specific embodiment of the present invention, the present invention also provides a mold tooling for casting wax models, and a wax injection pressing process for manufacturing casting wax models, ultimately producing a product as shown in the figure. Figure 1 The wax model 10 of the casting shown.

[0057] like Figure 4 and Figure 5As shown, the mold tooling for casting wax models includes a casting wax model mold and the aforementioned cold wax structure. The casting wax model mold has the same outline shape as the cold wax body 1, and the size of the cold wax body 1 is smaller than that of the casting wax model mold, thus allowing the cold wax body 1 to be positioned and installed within the cavity of the casting wax model mold. Specifically, the casting wax model mold includes an upper mold body (not shown) and a lower mold body 5 that interlock, and the upper mold body and lower mold body 5, when interlocked, form a cavity. When a casting wax model 10 needs to be prepared, the cold wax structure is placed within the cavity and installed at a preset position. Specifically, a positioning post 7 is provided on the lower mold body 5, and the positioning post 7 engages with the positioning hole 3 to position the cold wax structure at the preset position.

[0058] In an embodiment of the present invention, the cold wax structure is installed in the casting wax mold using a pinhole positioning method. The casting wax mold is divided into upper and lower parts. Three positioning posts 7 are designed on the lower mold body 5 corresponding to the installation position of the cold wax structure. When the cold wax structure is installed in the lower mold body 5, the lower surface of the cold wax body 1 with the positioning hole 3 faces downward and is inserted into the three positioning posts 7. When the upper mold body is closed, the three positioning protrusions 4 on the upper surface of the cold wax body 1 abut against the inner side of the upper mold body, realizing positioning in the axial direction of the positioning hole 3 and in the direction perpendicular to the axial direction of the positioning hole 3. After the mold is closed, the cold wax structure is stably positioned and there are no side protrusions.

[0059] like Figure 5 As shown, the positioning column 7 includes a fixedly connected limiting frustum and a connecting column, wherein the connecting column is inserted into the positioning hole 3.

[0060] In some embodiments of the present invention, the diameter of the connecting cylinder can be 2.7 mm and the height is not less than 5 mm. The diameter of the limiting frustum is 5 mm and the height can be designed according to the actual situation. Of course, all structural dimensions of the positioning frustum 7 can be adjusted and designed according to the actual situation, without specific limitations.

[0061] like Figure 4 As shown, there are gaps 8 between the upper surface, lower surface and side surface of the cold wax body 1 and the cavity wall of the casting wax mold.

[0062] In some embodiments of the present invention, the gap can be 3 to 5 mm. Of course, this gap is not specifically limited and can be set according to actual needs in actual operation.

[0063] According to a specific embodiment of the present invention, a pressing forming method for casting wax molds is also provided, which is based on the above-described mold tooling.

[0064] The pressing and forming method for casting wax patterns in this invention includes the following steps:

[0065] (1) Make cold wax structure.

[0066] In an embodiment of the present invention, the cold wax structure is obtained using a wax mold pressing process, see [link to relevant documentation]. Figure 2 and Figure 3 As shown, the cold wax structure shrinks after demolding, with a shrinkage rate of 0.4% to 0.8%. Specifically, after demolding, the cold wax structure needs to be cooled on the cold wax placement fixture for a certain period of time, such as 2 hours, to cool it to the ambient temperature of the wax pressing room. At this time, the cold wax structure shrinks to the design size.

[0067] It is worth mentioning that the design of the cold wax structure requires the analysis of the wall thickness of the casting wax mold 10. When the thickness exceeds the shrinkage limit of the wax material, a cold wax structure needs to be designed to ensure that the gap 8 between the cold wax structure and the cavity wall of the casting wax mold is uniform, that is, has the same spacing.

[0068] (2) The cold wax structure is placed in the cavity of the casting wax mold by positioning the positioning hole 3 on the cold wax body 1 and positioning the positioning column 7; wherein, the outlet 2 is set directly opposite the wax injection nozzle 9 of the casting wax mold; there are gaps 8 of the same distance between the upper surface, lower surface and side of the cold wax body 1 and the cavity wall of the casting wax mold.

[0069] In an embodiment of the present invention, the gap is set to 3-5 mm.

[0070] In an embodiment of the present invention, the longitudinal cross-sectional area at the inlet of the drainage port 2 is not less than twice the longitudinal cross-sectional area of ​​the wax injection nozzle 9, so that the diffusion and diversion at the drainage port 2 can be effectively carried out, and at the same time, it is convenient for the wax liquid to be injected.

[0071] (3) Inject wax liquid into the cavity of the casting wax mold through the wax injection nozzle 9. The wax liquid diffuses and flows at the outlet 2 and evenly covers the upper surface, lower surface and side surface of the cold wax body 1 until it fills the gap 8. At this time, the entire cavity is also filled with wax liquid.

[0072] In an embodiment of the present invention, the wax liquid enters the cavity of the casting wax mold by pressure from the wax press. Due to the design of the outlet 2 on the cold wax body 1, the wax liquid is split at the outlet 2. Part of it spreads and flows left and right along the mold surface, i.e. the side surface, of the cold wax body 1, and part of it penetrates the surface of the cold wax body 1 through the outlet 2, forming a wax liquid coating on both the upper and lower surfaces of the cold wax body 1. This avoids the cold wax structure from being impacted by the wax injection pressure in the casting wax mold, resulting in single-sided pressure and causing the cold wax structure to shift. This ensures that the cold wax structure is centered in the casting wax mold.

[0073] (4) After wax injection, a casting wax model 10 containing a cold wax structure is obtained, and then the casting wax model 10 is removed from the cavity of the casting wax model mold.

[0074] In an embodiment of the present invention, after wax injection, the casting wax model 10 is ejected from the cavity of the casting wax model mold by pneumatic ejection or mechanical ejection. The ejection height needs to exceed 10mm. The casting wax model 10 is smoothly ejected from the mold and detached from the positioning column 7 without shaking.

[0075] (5) The surface of the casting wax model 10 obtained in step (4) is repaired. Only the three wax holes on the lower surface of the casting wax model 10 need to be repaired to complete the surface repair of the entire casting wax model 10. The size of the casting wax model 10 is minimally affected and the surface finish of the casting wax model 10 is high.

[0076] It should be noted that the wax cavity was formed due to the positioning and matching of the cold wax structure and the positioning column 7.

[0077] It should be noted that the term "comprising" and any variations thereof in the specification and claims of this invention are intended to cover non-exclusive inclusion, for example, including a series of components that are not necessarily limited to those explicitly listed, but may include other components that are not explicitly listed or that are inherent to the component.

[0078] In this invention, the terms "upper," "lower," "bottom," "top," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0079] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0080] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0081] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A cold wax structure for casting wax models, characterized in that, Includes a cold wax body and a drain port and positioning components disposed on the cold wax body; The drain port is located at the edge of the cold wax body and is positioned directly opposite the wax injection nozzle of the casting wax mold, so that the wax liquid is divided at the drain port. Part of the wax liquid diffuses and flows laterally along the surface of the cold wax body, and part of the wax liquid penetrates the surface of the cold wax body through the drain port. The longitudinal cross-sectional area at the entrance of the drain port is not less than twice the longitudinal cross-sectional area of ​​the wax injection nozzle. The positioning component includes a positioning hole, which is disposed on the lower surface of the cold wax body and / or through the upper and lower surfaces of the cold wax body; the diameter of the positioning hole is 2.8~3.5mm.

2. The cold wax structure according to claim 1, characterized in that, The drainage port is a notch or groove opened at the edge of the cold wax body.

3. The cold wax structure according to claim 1, characterized in that, The drainage port is rectangular or hemispherical in shape.

4. The cold wax structure according to claim 1 or 2, characterized in that, The positioning component also includes a positioning protrusion disposed on the upper surface of the cold wax body.

5. The cold wax structure according to claim 4, characterized in that, The positioning protrusion is hemispherical.

6. A mold tooling for casting wax models, characterized in that, Includes a casting wax mold and a cold wax structure as described in any one of claims 1-5; wherein, The casting wax mold has the same outline shape as the cold wax body, and the size of the cold wax body is smaller than the size of the casting wax mold; The casting wax mold includes an upper mold body and a lower mold body that are interlocked, and the two together form a cavity; the cold wax structure is detachably placed inside the cavity; The lower mold body is provided with a positioning column, which is positioned and engaged with the positioning hole; the positioning column includes a limiting frustum and a connecting cylinder that are fixedly connected, and the connecting cylinder is inserted and engaged with the positioning hole.

7. The mold tooling according to claim 6, characterized in that, There are gaps between the upper surface, lower surface, and side surface of the cold wax body and the cavity wall of the casting wax mold.

8. A method for pressing and forming a wax model of a casting, characterized in that, The pressing and forming method is based on the mold tooling according to any one of claims 6-7; the pressing and forming method includes the following steps: Fabrication of cold wax structures; The cold wax structure is placed in the cavity through the positioning hole and the positioning column; wherein, the drain port is set directly opposite the wax injection nozzle of the casting wax mold; there are gaps of the same distance between the upper surface, lower surface and side of the cold wax body and the cavity wall of the casting wax mold; Molten wax is injected into the cavity of the casting wax mold through the wax injection nozzle. The molten wax diffuses and flows at the outlet and evenly coats the upper surface, lower surface and side surface of the cold wax body until the gap is filled. After wax injection is completed, a casting wax model containing the cold wax structure is obtained, and then the casting wax model is removed from the cavity of the casting wax model mold.

9. The pressing and forming method according to claim 8, characterized in that, The cold wax structure is made by a wax mold pressing process. After the cold wax structure is demolded, it is cooled for a certain period of time to shrink to the design size. The shrinkage rate of the cold wax structure is 0.4~0.8%.

10. The pressing and forming method according to claim 8, characterized in that, The casting wax model is ejected from the cavity of the casting wax model mold by pneumatic ejection or mechanical ejection.

11. The pressing and forming method according to claim 8, characterized in that, The gap is 3~5mm.

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