A wax pattern, a method of making and using a lost wax cast part

Abstract

The present application relates to the technical field of investment precision casting, in particular to a wax mold, a preparation method and application of an investment casting casting. The wax mold is provided with at least one process hole, the process hole is a through hole; the height of the process hole is 15-20 mm with the wax mold as a base surface; the process hole has a flange, the thickness of the flange is 5-10 mm; the wax mold further comprises at least one blocking wax piece, the blocking wax piece is matched with the size of the process hole. The present application can effectively prevent the shell from bulging, and the process hole of the shell generated at the same time is closed during subsequent shell blocking, and the casting does not need to be welded and blocked after pouring. The poured casting has no process hole and does not need to be repaired. The purpose of controlling the bulging deformation of the photosensitive resin shell and the casting without the process hole can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of investment precision casting, in particular to a wax mold, a preparation method and application of an investment casting. BACKGROUND

[0002] Investment precision casting technology is a casting technology evolved from the lost wax method, mainly referring to making wax into a corresponding model, coating the outer part of the wax model with refractory material, then using heating method or using high-temperature water vapor to make the wax soften and flow out of the refractory material, obtaining an empty shell wrapped by refractory material, baking the shell to make it ceramic and have certain strength. Then melt the required metal material and pour it into the empty shell wrapped by refractory material.

[0003] Photosensitive resin has the characteristics of good surface roughness and high dimensional accuracy, and is widely used in the casting industry. However, the shell has not been ceramicized, and its own structural strength is low during the production process of investment casting. The expansion coefficient of photosensitive resin is much larger than that of the shell, which leads to the bulging and even cracking of the shell during the baking process. Specifically, the bulging of the photosensitive resin shell mainly occurs in the shell baking stage: the photosensitive resin needs to be directly put into the furnace above 800 DEG C for "flash burning" due to its own unique thermal expansion effect, so that the photosensitive resin burns quickly to reduce its thermal expansion. However, when the number of layers of the shell is low and the structural strength of the shell itself is low, the thermal expansion of the photosensitive resin will cause the bulging and cracking of the shell.

[0004] In order to prevent the bulging and deformation of the shell, a method of opening a process hole is usually used, as shown in Figure 1 , the process hole connects the shell during shell preparation, fixes the two layers of the shell wall, further strengthens the shell, and effectively prevents the deformation of the shell. In order to make the shell double wall play an effective connecting role, the diameter of the process hole is generally , so that the shell at the process hole has a certain strength. However, after the shell is prepared , the process hole is often plugged with shell material, which leads to local thermal joints, is not conducive to the heat dissipation of the shell after pouring, and may affect the metallurgical quality of the casting and cause porosity defects. Moreover, the process hole formed on the casting is closed by subsequent welding, but due to the large welding area, deformation is easy to occur during welding for thin-walled castings, which leads to size out-of-tolerance of the castings. The welding flash is also easy to cause the polishing loss at the welding "bite edge" position during polishing, as shown in Figure 2 .

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The first object of the present application is to provide a wax mold, which comprises a process hole and a blocking wax piece, can effectively prevent the shell from bulging, and the process hole of the shell generated can be closed during subsequent shell blocking, and the castings poured out do not need to be welded for blocking, the blocked shell has no process hole, and the castings poured out also do not need to be supplemented for blocking the process hole.

[0007] The second object of the present application is to provide a preparation method of an investment casting, using which the process hole of the shell can be blocked by using a blocking cover after the shell is baked, the castings poured out have no process hole, and do not need to be supplemented, and problems such as welding undercutting and deformation generated during the process hole supplementing can be avoided.

[0008] The third object of the present application is to provide an application of the wax mold or the preparation method of the investment casting in the preparation of the investment casting.

[0009] In order to achieve the above objects of the present application, the following technical solutions are adopted:

[0010] The present application first provides a wax mold, which is provided with at least one process hole, and the process hole is a through hole; the height of the process hole is 15-20 mm with the wax mold as a base surface; the process hole has a flange, and the thickness of the flange is 5-10 mm; the wax mold further comprises at least one blocking wax piece, and the blocking wax piece is matched with the size of the process hole.

[0011] Further, the inner diameter of the process hole is 6-20 mm.

[0012] Further, the blocking wax piece has a step, and the step is matched with the size of the flange of the process hole.

[0013] Further, the number of the blocking wax pieces is twice the number of the process holes.

[0014] Further, the material of the wax mold, the process hole and the blocking wax piece comprises photosensitive resin.

[0015] The present application further provides a preparation method of an investment casting, using the wax mold, and the preparation method of the investment casting comprises the following steps: coating a refractory material on the surface of the wax mold with a process hole, and then baking to obtain a shell; wherein the refractory material on the surface of the process hole forms a shell process hole after baking; coating a refractory material on the blocking wax piece, and then baking to obtain a blocking cover; removing the shell at both ends of the shell process hole and the shell inside the shell process hole to obtain a shell process hole to be blocked; inserting the blocking cover into the inside of the shell process hole to be blocked, and coating the refractory material on the outside of the blocking cover to connect the blocking cover and the shell, and then baking and pouring to obtain the investment casting.

[0016] Furthermore, the plug is matched to the size of the process hole in the shell to be sealed.

[0017] Furthermore, along the diameter direction of the plug, there is an assembly gap of 0.05 to 0.2 mm between the plug and the process hole of the shell to be sealed.

[0018] Furthermore, the plug is made of the same material as the shell.

[0019] The present invention also provides the application of the method for preparing the wax pattern or the investment casting in the preparation of investment castings.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The wax model provided by the present invention includes process holes and plugging wax parts. The wax model can effectively prevent the shell from bulging. At the same time, the process holes of the shell generated are closed when the shell is sealed in the subsequent shell sealing. After the casting is poured out, there is no need to weld and seal. The shell after sealing has no process holes, and the cast casting does not need to be re-welded to seal the process holes.

[0022] (2) The method for preparing investment casting provided by the present invention allows the process holes in the mold shell to be sealed with plugs after the mold shell is baked, and the cast parts have no process holes and do not require welding.

[0023] (3) The method for preparing investment casting provided by the present invention can improve the strength of the mold shell and prevent it from cracking during firing.

[0024] (4) The method for preparing investment casting provided by the present invention is simple to operate. The mold shell can be sealed by plugging, and the purpose of controlling the expansion and deformation of the mold shell for photosensitive resin and the casting without process holes can be achieved. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 Images showing the existing technology of creating process holes in the shell;

[0027] Figure 2 Images of weld beads in existing castings;

[0028] Figure 3 A partial schematic diagram of the wax model provided by the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of the process hole provided by the present invention;

[0030] Figure 5 This is a schematic diagram of the shell structure provided by the present invention;

[0031] Figure 6 The production process flow diagram of the plug provided by the present invention;

[0032] Figure 7 This is a schematic diagram of the structure of the process hole in the shell to be sealed provided by the present invention;

[0033] Figure 8 This is a schematic diagram of the structure of the process hole after sealing provided by the present invention;

[0034] Figure 9 The image shows the shell obtained in Comparative Example 1 of this invention cracking.

[0035] Figure 10 This is an image showing the swelling of the investment casting obtained in Comparative Example 1 of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0037] Unless otherwise specified, in this invention, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," "third," and "fourth" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0038] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0039] Unless otherwise specified, in this invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0040] In a first aspect, the present invention provides a wax model having at least one process hole, such as one, two, three, four, five, six, eight, ten, or more. The process hole is a through hole.

[0041] It is understandable that the number of process holes is related to the size of the product; the larger the size, the more process holes are required. It is also related to the product structure, so the number of process holes can be set as needed.

[0042] Figure 3 This is a partial schematic diagram (cross-sectional view) of a wax model with process holes.

[0043] Figure 4 This is a schematic diagram of the process hole structure.

[0044] Using the wax model as the base surface, the height of the process hole is 15-20mm (i.e., the thickness of the process hole on one side of the wax model is 15-20mm), including but not limited to any one of 15mm, 16mm, 17mm, 18mm, 19mm, and 20mm, or any range between two of them. That is, the process hole protrudes 15-20mm above the surface of the wax model, which facilitates the preparation of the shell at the process hole. If the height of the process hole is too low, the shell at the process hole is not conducive to preparation, and the resulting angle is prone to falling off. If the height of the process hole is too high, the required size of the plugging wax part should also be larger, and the protruding process hole is also at risk of being knocked off during shell transfer.

[0045] The process hole has a flange with a thickness of 5-10 mm, including but not limited to a value of any one of 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm, or a range between any two. The flange refers to the protrusions at both ends of the process hole. The flange facilitates cleaning of the shell at the process hole. However, if the flange is too small, removing the shell from the surface of the process hole may damage the stepped portion of the lower process hole, hindering the location of blockages; if the flange is too high, there is a risk of introducing shell fragments into the shell.

[0046] The wax mold also includes at least one plugging wax element, such as one, two, three, four, five, six, eight, ten, or more. The plugging wax element is sized to match the process hole. The plugging wax element is used to form a cap to seal the shell process hole.

[0047] The wax model provided by this invention can effectively prevent the mold shell from bulging. Simultaneously, the resulting process holes in the mold shell are sealed during subsequent mold shell plugging, eliminating the need for welding sealing after casting. The sealed mold shell has no process holes, and the cast part does not require additional welding to seal the process holes.

[0048] In some specific implementations, during the 3D model design stage, process holes with flanges are designed on the model, and the process holes are made together with the wax model.

[0049] In some specific implementations, a three-dimensional model for the plugging wax is designed, and the plugging wax (i.e., the outer shell of the plug) is manufactured.

[0050] In some specific embodiments, the inner diameter of the process hole is 6–20 mm, including but not limited to any one of 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, and 20 mm, or a range between any two. If the inner diameter of the process hole is too small, the mold shell is difficult to prepare, and the connection strength between the inner and outer shells is low, posing a risk of breakage during firing. If the inner diameter of the process hole is too large, for irregularly shaped or curved structures, the process hole will affect the final dimensions of the casting. Limiting the inner diameter of the process hole to a certain range ensures sufficient strength at the process hole in the mold shell while avoiding any impact on the dimensions of the casting.

[0051] In some specific embodiments, the plugging wax component has a step, and the step matches the size of the flange of the process hole. This restricts the position of the plugging wax component and the plug cap, ensuring the wall thickness after the process hole is sealed.

[0052] In some specific embodiments, the number of the plugging wax pieces is twice the number of the process holes, that is, two plugging wax pieces are configured for each process hole.

[0053] In some specific embodiments, the materials of the wax mold, the process hole, and the plugging wax include photosensitive resin and other wax mold materials that expand when heated.

[0054] When it is necessary to open process holes to increase the strength of the shell, the above-mentioned wax pattern and the following investment casting preparation methods can be used.

[0055] Secondly, the present invention provides a method for preparing investment castings, a method for sealing process holes in the mold shell, and a method for controlling the bulging deformation of the mold shell (including mold shells for photosensitive resin). Using the wax pattern, the method for preparing the investment casting includes the following steps:

[0056] A refractory material is coated onto the surface of a wax model with process holes, and then fired (the wax model melts during firing) to obtain a shell. See the schematic diagram of the shell structure. Figure 5 As shown. The refractory material on the surface of the process hole is calcined to form a shell-shaped process hole. It can be understood that after the shell is formed, the original process hole is transformed into a shell-shaped process hole.

[0057] A refractory material is coated onto the plugging wax, and then it is fired (the plugging wax melts during firing) to obtain the plug cap. See the production process flow diagram for the plug cap. Figure 6 .

[0058] Remove the shell material from both ends of the shell process hole and the shell material inside the shell process hole to obtain the shell process hole to be sealed. See the schematic diagram of the shell process hole to be sealed. Figure 7 As shown.

[0059] The plug is inserted into the process hole of the shell to be sealed, and the refractory material is coated on the outside of the plug. Then it is fired to obtain the sealed process hole. See the schematic diagram for its structure. Figure 8 As shown. Then, pouring is performed to obtain the investment casting. That is, the process holes in the shell to be sealed are sealed with plugs.

[0060] The method for preparing investment castings provided by this invention can effectively prevent the mold shell from bulging. At the same time, the process holes in the mold shell generated can be sealed during subsequent mold shell sealing. After the casting is poured, there is no need for welding sealing, and the investment castings after pouring have no process holes.

[0061] Furthermore, the method for preparing investment castings provided by this invention can improve the strength of the mold shell and prevent it from cracking during firing.

[0062] Furthermore, the method for preparing investment castings provided by this invention is simple to operate, and the shell can be sealed by plugging.

[0063] The process holes formed after the shell baking of the present invention are sealed with plugs. Compared with conventional photosensitive resin process holes, this invention can achieve the purpose of controlling the expansion and deformation of the shell for photosensitive resin and eliminating process holes in the casting.

[0064] In some specific embodiments, the plug is matched to the size of the process hole in the shell to be sealed.

[0065] In some specific embodiments, a 0.05–0.2 mm (e.g., 0.1 mm or 0.15 mm) assembly gap is left between the plug and the process hole of the shell to be sealed along the diameter direction of the plug.

[0066] In this invention, the main function of the plug is to seal the process holes of the shell to be sealed. The plug can be made of ceramic, metal, etc., as long as it meets the size requirements and does not react with the metal.

[0067] In some specific embodiments, the plug and the mold shell are made of the same material; that is, the refractory material used to coat the surface of the wax model is the same as the refractory material used to coat the plug wax. This effectively prevents displacement caused by the difference in their coefficients of expansion during the preheating process of the mold shell.

[0068] In some specific implementations, during the firing process of the mold shell, the mold shells on both sides of the process hole are connected to increase the strength of the mold shell cavity and prevent the wax mold (photosensitive resin) from expanding due to heat, which would cause the mold shell to bulge and crack.

[0069] Thirdly, the present invention provides the application of the method for preparing the wax pattern or the investment casting in the preparation of investment castings.

[0070] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0071] Example 1

[0072] This embodiment provides a wax model, product name: Front Section. The wax model has two process holes, which are through holes with an inner diameter of 12mm. The process holes protrude 18mm above the wax model surface, with the process holes having a flange thickness of 8mm. The wax model also includes four plugging wax pieces, each with a step, and the dimensions of the plugging wax pieces match the process holes (the steps also match the flange). The wax model, process holes, and plugging wax pieces are all made of photosensitive resin.

[0073] Example 2

[0074] This embodiment provides a wax model, product name: Rear Section. The wax model has four process holes, which are through holes with an inner diameter of 6mm. The process holes protrude 15mm above the wax model surface, with the process holes having a flange thickness of 5mm. The wax model also includes eight plugging wax pieces, each with a step, and the dimensions of the plugging wax pieces match the process holes (the steps also match the flanges). The wax model, process holes, and plugging wax pieces are all made of photosensitive resin.

[0075] Example 3

[0076] This embodiment provides a wax model, product name: casing. The wax model has three process holes, which are through holes with an inner diameter of 20mm. The process holes protrude 20mm above the wax model surface, with the process holes having a flange thickness of 10mm. The wax model also includes six plugging wax pieces, each with a step, and the dimensions of the plugging wax pieces match the process holes (the steps also match the flanges). The wax model, process holes, and plugging wax pieces are all made of photosensitive resin.

[0077] Example 4

[0078] This embodiment provides a method for preparing investment castings. Using the wax pattern from Example 1, the method for preparing investment castings includes the following steps:

[0079] A refractory material is coated onto the surface of the wax mold with process holes. Specifically, the surface layer uses a slurry formed by silica sol and zircon powder, with white corundum as the surface sand. The back layer uses a slurry formed by coal gangue powder and silica sol, with mullite sand as the back sand. The sealing layer slurry is the same as the back layer slurry, but only seals the surface without sprinkling sand. The mold is then fired to obtain a shell. The refractory material on the surface of the process holes forms the process holes in the shell after firing.

[0080] A refractory material (the same material used on the wax model) is coated onto the plugging wax piece, and then fired to obtain the plug. The plug is made of the same material as the shell.

[0081] Remove the shell material from both ends of the shell process hole and the shell material inside the shell process hole to obtain the shell process hole to be sealed. The plug is sized to match the shell process hole to be sealed, and a 0.1mm assembly gap is left between the plug and the shell process hole along the diameter direction of the plug.

[0082] Insert the plug into the process hole of the shell to be sealed, and coat the outside of the plug with refractory material (the same material coated on the wax pattern). After firing, pour the casting to obtain the investment casting.

[0083] Example 5

[0084] The preparation method of the investment casting provided in this embodiment is basically the same as that in embodiment 4, except that the wax model of embodiment 2 is used.

[0085] Example 6

[0086] The preparation method of the investment casting provided in this embodiment is basically the same as that in embodiment 4, except that the wax model of embodiment 3 is used.

[0087] Comparative Example 1

[0088] The wax model of this comparative example is basically the same as that of Example 3, except that it has no process holes. Using the wax model of this comparative example, an investment casting was prepared according to the method for preparing investment castings in Example 4.

[0089] Comparative Example 2

[0090] The wax model of this comparative example is basically the same as that of Example 3, except that it lacks process holes. Using the wax model of this comparative example, and referring to the preparation method of the investment casting casting in Example 4, process holes are made during shell making to connect the shell and fix the two layers of the shell wall. The diameter of the hole is 12mm. See [link to relevant documentation]. Figure 1 As shown, an investment casting casting was obtained.

[0091] The bulging and cracking of the shells in each embodiment and comparative example are shown in Table 1.

[0092] Table 1 shows the shell bulging and cracking in each embodiment and comparative example.

[0093] Group Whether the shell is bulged Whether the shell is cracked Whether the process hole is repaired Example 4 No No No Example 5 No No No Example 6 No No No Comparative Example 1 Yes Yes No Comparative Example 2 No No Yes

[0094] For the image showing the cracking of the shell obtained in Comparative Example 1, please refer to [link / reference]. Figure 9 For a comparison of the image showing the bulging of the investment casting obtained in Example 1, please refer to [the image description]. Figure 10 .

[0095] Therefore, the present invention can effectively prevent the mold shell from bulging, improve the strength of the mold shell, avoid cracking during firing, and the cast parts produced have no process holes and do not require welding repair.

[0096] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A wax model, characterized in that, The wax mold is provided with at least one process hole, which is a through hole; Using the wax mold as the base surface, the height of the process hole is 15~20mm; The process hole has a flange, and the thickness of the flange is 5~10mm; The wax mold also includes at least one plugging wax element, the plugging wax element being matched to the size of the process hole; The number of plugging wax pieces is twice the number of process holes; The materials of the wax mold, the process hole, and the plugging wax include photosensitive resin.

2. The wax model according to claim 1, characterized in that, The inner diameter of the process hole is 6~20mm.

3. The wax model according to claim 1, characterized in that, The plugging wax has a step, and the step matches the size of the flange of the process hole.

4. A method for preparing an investment casting, using a wax pattern as described in any one of claims 1 to 3, characterized in that, The method for preparing the investment casting includes the following steps: A refractory material is coated on the surface of a wax mold with process holes, and then fired to obtain a shell; wherein, the refractory material on the surface of the process holes forms the process holes of the shell after firing. A refractory material is coated onto the plugging wax, and then it is fired to obtain a plug. Remove the shells at both ends of the shell process hole and the shell inside the shell process hole to obtain the shell process hole to be sealed. The plug is inserted into the process hole of the shell to be sealed, and the refractory material is coated on the outside of the plug to connect the plug and the shell. After baking, it is poured to obtain the investment casting.

5. The method for preparing investment castings according to claim 4, characterized in that, The plug is matched to the size of the process hole in the shell to be sealed.

6. The method for preparing investment castings according to claim 5, characterized in that, Along the diameter direction of the plug, there is an assembly gap of 0.05~0.2mm between the plug and the process hole of the shell to be sealed.

7. The method for preparing investment castings according to claim 4, characterized in that, The plug is made of the same material as the shell.

8. The application of the method for preparing a wax model as described in any one of claims 1 to 3 or a method for preparing an investment casting as described in any one of claims 4 to 7 in the preparation of investment castings.

Images