Method for reducing cracking of deep narrow structure shell of titanium alloy engine case

Abstract

The application discloses a method for reducing cracking of a titanium alloy machine case deep and narrow structure type shell, and belongs to the field of titanium alloy investment casting. The method is characterized in that the back 5-7 layers of the machine case are coated and hung, and then sand filling, pipe inserting and plugging and other operations are performed, so that the problem that the machine case support plate is prone to cracking in the steam dewaxing process due to low strength of the type shell is reduced; the two ways of filling sand in the back layer support plate and adding stainless steel pipes (corundum pipes) are combined, traditional complicated methods such as overall optimization of the shell preparation process, special preparation of the support plate core filling material and artificial intervention in the support plate coating and hanging are avoided, the method is simple and convenient, the stability of the process is ensured, the support plate deformation and uneven thickness can be prevented, the internal and external pressure balance can be maintained, the risk of cracking of the machine case deep and narrow support plate structure is reduced, and the shell quality is improved; the application solves the problem that the titanium alloy machine case deep and narrow support plate structure is prone to cracking in the steam dewaxing process, avoids the problem that the machine case support plate cracking leads to shell scrapping, and effectively ensures the shell quality.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy investment casting precision casting, and particularly relates to a method for reducing cracking of deep and narrow structural shells of titanium alloy casings. Background Technology

[0002] In the process of titanium alloy investment casting, the casing casting often has a deep and narrow support plate structure. In addition to the problem that the sharp corners dry relatively quickly and the sand is difficult to adhere, the gap between the support plates becomes narrower and narrower as the number of coating layers gradually increases. This makes problems such as bridging and difficulty in adhering coarse sand in the inner cavity coating more and more obvious. As a result, the support plates often crack during the subsequent steam dewaxing process due to insufficient strength. This problem of support plate cracking is particularly obvious in the fully automated shell making process, which greatly reduces the pass rate and actual efficiency of automated shell making. Currently, the main methods to solve the problem of support plate cracking are threefold: optimizing the shell-making process, specially formulating support plate core-filling materials, and manually intervening in the support plate coating process. These methods not only make the process increasingly complex and difficult to control, but also greatly reduce production efficiency. This process method mainly utilizes back layer sand to fill the support plate, which can not only reduce the subsequent internal cavity void, but also prevent problems such as support plate deformation and uneven thickness. Combined with the insertion of stainless steel tubes or corundum tubes into the support plate to balance the pressure difference between the internal cavity filling material and the external environment, the impact of excessive pressure difference is reduced. The combination of these two methods is not only simple and efficient in operation, but also can well guarantee the quality of subsequent castings.

[0003] Large titanium alloy housings, due to their deep and narrow support plate structure, experience increasingly smaller gaps between the support plates as the back layer is successively coated. This leads to sand bridging within the support plate cavities and difficulty in adhering to coarse sand particles. Especially during automated robotic sand application, some support plates may even lack sand adhesion on their sides or tips. During steam dewaxing, the support plate structure, due to internal and external pressure differences caused by insufficient coarse sand, suffers from low strength, resulting in cracking after dewaxing. By filling the back layer support plates with sand and inserting stainless steel or corundum tubes, the problem of sand bridging and the resulting gaps are avoided. Furthermore, the internal pressure can be channeled through the tubes to maintain internal and external pressure balance, reducing the risk of shell support plate cracking. The effective combination of sand filling and tube insertion significantly reduces problems such as cracking in the deep and narrow support plate structure of the housing. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method to reduce the cracking of the deep and narrow structure shell of titanium alloy casing, which solves the problem that the deep and narrow support plate structure of titanium alloy casing is prone to cracking during steam dewaxing, avoids the problem of casing shell scrapping due to cracking of the casing support plate, and effectively ensures the quality of the casing.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A method for reducing cracking in deep and narrow structure shells of titanium alloy casings, specifically comprising the following steps;

[0007] Step 1: Determine which layer of coating (5-8 layers) to apply sand to after the casing support plate gap width d1; where the width d1 is 15mm-55mm.

[0008] Step 2: After determining the sand filling layer, proceed with the normal application of the first few back coating layers. At the same time, clean the loose sand and sand bridging inside the support plate after each coating layer before the sand filling layer.

[0009] Step 3, prepare stainless steel pipes;

[0010] Step 4: Wrap the open ends of the stainless steel tube with gauze;

[0011] Step 5: Select the back layer sand and slowly pour it into the inner cavity of the support plate, continuously tamping it with a saw blade tool. At the same time, put in a stainless steel pipe, keeping the pipe upright in the sand, and fill it up to 20mm-30mm away from the opening section of the support plate.

[0012] Step 6: Prepare the sealing material according to the powder-sand-liquid ratio of about 3:2:1, and then tamp the sealing layer of about 20mm-30mm in the support plate opening section to prevent the subsequent filling sand material from leaking out. After the opening section is sealed, let it dry for about 6-8 hours.

[0013] Step 7: After drying, proceed with the subsequent back layer operations and drying according to the normal coating process until the sealing layer coating is completed.

[0014] Step 8: After the sealing layer has dried, use a cutting machine to cut off the stainless steel end, ensuring that the cut end of the pipe is free of slurry blockage and allows for smooth airflow.

[0015] Step 9: Set the shell dewaxing temperature to 170-180℃, the pressure to 0.7-0.8MPa, the dewaxing time to 10-12min, and the pressure relief rate to 0.06-0.07MPa / min. After dewaxing, let it stand for 4-5 hours, and then bake it at high temperature.

[0016] As a further preferred embodiment of the method for reducing cracking of deep and narrow structure shells of titanium alloy casings according to the present invention, in step 3, the stainless steel tube can be replaced by a corundum tube.

[0017] As a further preferred embodiment of the method for reducing cracking of deep and narrow structure shells of titanium alloy casings according to the present invention, the diameter d2 of the stainless steel tube or corundum tube is 6mm-10mm, and the total length is 30mm-40mm longer than the depth of the support plate.

[0018] As a further preferred embodiment of the method for reducing cracking of deep and narrow structure shells of titanium alloy casings according to the present invention, the back layer sand particles are 16-60 mesh sand particles.

[0019] As a further preferred embodiment of the method for reducing cracking in deep and narrow titanium alloy casings according to the present invention, in step 5, the diameter d3 of the stainless steel tube is 6mm-10mm. Compared with the prior art, the present invention, using the above technical solution, has the following technical effects:

[0020] This invention provides a method for reducing cracking in deep and narrow titanium alloy casing shells. By combining sand filling in the back support plate and inserting stainless steel tubes (corundum tubes), it avoids the traditional cumbersome methods such as overall optimization of the shell manufacturing process, special formulation of support plate filling materials, and manual intervention in support plate coating. This method is not only simple and convenient, ensuring process stability, but also prevents support plate deformation and uneven thickness, and maintains internal and external pressure balance. Ultimately, it reduces the risk of cracking in the deep and narrow support plate structure of the casing and improves the quality of the casing shell. Attached Figure Description

[0021] Figure 1 This is a flowchart of a method for reducing cracking in deep and narrow structure shells of titanium alloy casings according to the present invention;

[0022] Figure 2 This is a schematic diagram and cross-sectional view of the sand filling and pipe insertion of the support plate of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings:

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0025] This invention provides a method to reduce cracking of the deep and narrow structure shell of a titanium alloy casing. After applying 5-7 layers of coating to the back of the casing, sand filling, pipe insertion, and sealing are performed. This reduces the problem of the casing support plate being prone to cracking during steam dewaxing due to the low strength of the shell.

[0026] This invention solves the problem of cracking in the deep and narrow support plate structure of titanium alloy casing shell during steam dewaxing, avoids the problem of casing shell being scrapped due to cracking of the casing support plate, and effectively ensures the quality of the casing shell.

[0027] The technical solution to be solved by this invention is:

[0028] A method for reducing cracking in deep and narrow structural shells of titanium alloy casings, such as Figure 1 and Figure 2 As shown, the specific steps are as follows;

[0029] Step 1: Determine which layer of coating (5-8 layers) to apply sand to after the casing support plate gap width d1; where the width d1 is 15mm-55mm.

[0030] Step 2: After determining the sand filling layer, proceed with the back coating of the first few layers as usual, ensuring that after each layer of coating is applied before the sand filling layer, the loose sand and sand bridging inside the support plate cavity are cleaned in time.

[0031] Step 3: Prepare stainless steel pipes or corundum pipes; the diameter d2 of the stainless steel pipes or corundum pipes is 6mm-10mm, and the total length is 30mm-40mm longer than the depth of the support plate.

[0032] Step 4: Wrap the openings at both ends of the stainless steel or corundum tube with gauze to prevent the subsequent filling material from overflowing or spraying out of the tube.

[0033] Step 5: Select 16-60 mesh sand for the back layer and slowly pour it into the inner cavity of the support plate. Use a saw blade tool to tamp it down continuously. At the same time, put in a stainless steel pipe or corundum pipe, keeping the pipe upright in the sand. Fill it up to 20mm-30mm away from the opening of the support plate.

[0034] Step 6: Prepare the sealing material according to the powder-sand-liquid ratio of about 3:2:1, and then tamp the sealing layer of about 20mm-30mm in the support plate opening section to prevent the subsequent filling sand material from leaking out. After the opening section is sealed, let it dry for about 6-8 hours.

[0035] Step 7: After drying, proceed with the subsequent back layer operations and drying according to the normal coating process until the sealing layer coating is completed.

[0036] Step 8: After the sealing layer has dried, use a cutting machine to cut off the ends of the stainless steel or corundum tubes, ensuring that the cut ends of the tubes are free of slurry blockage and allow for smooth airflow.

[0037] Step 9: Set the shell dewaxing temperature to 170-180℃, the pressure to 0.7-0.8MPa, the dewaxing time to 10-12min, and the pressure relief rate to 0.06-0.07MPa / min. After dewaxing, let it stand for 4-5 hours, and then bake it at high temperature.

[0038] By combining the filling of sand into the back support plate and the insertion of stainless steel tubes (corundum tubes), not only can the deformation and uneven thickness of the support plate be prevented, but the internal and external pressure balance can also be maintained, reducing the risk of cracking in the deep and narrow support plate structure of the casing.

[0039] The sand filling material of the support plate is the same as that of the back layer material, which ensures the stability of the overall shell thermal expansion. This not only has no impact on the existing shell process, but also reduces production costs.

[0040] Compared to the traditional method of dealing with loose sand in the inner cavity of the support plate at each level, the sand filling and pipe insertion method is not only simple and convenient to operate, but also eliminates the need to deal with loose sand in the support plate after the sand filling is completed. This not only frees up manpower but also greatly improves production efficiency.

[0041] After the sealing layer has dried, use a cutting machine to cut off the stainless steel end, ensuring that the pipe cut is free of slurry blockage and allows for smooth airflow. Set the shell dewaxing temperature to 170-180℃, the pressure to 0.7-0.8MPa, the dewaxing time to 10-12min, and the pressure relief rate to 0.06-0.07MPa / min.

[0042] By combining sand filling in the back support plate and inserting stainless steel tubes (corundum tubes), the traditional cumbersome methods of optimizing the overall shell manufacturing process, specially preparing support plate filling materials, and manually intervening in the support plate coating are avoided. This method is not only simple and convenient, ensuring the stability of the process, but also prevents support plate deformation and uneven thickness, and maintains internal and external pressure balance. Ultimately, it reduces the risk of cracking in the deep and narrow support plate structure of the casing and improves the quality of the shell.

[0043] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0044] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention. The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for reducing cracking in deep and narrow structural shells of titanium alloy casings, characterized in that: Specifically, it includes the following steps; Step 1: Determine which layer of coating (5-8 layers) to apply sand to after the casing support plate gap width d1; where the width d1 is 15mm-55mm. Step 2: After determining the sand filling layer, proceed with the normal application of the first few back coating layers. At the same time, clean the loose sand and sand bridging inside the support plate after each coating layer before the sand filling layer. Step 3, prepare stainless steel pipes; Step 4: Wrap the open ends of the stainless steel pipe with gauze; Step 5: Select the back layer sand and slowly pour it into the inner cavity of the support plate. Use a modified saw blade tool to tamp it down continuously. At the same time, put in a stainless steel pipe and keep the pipe upright in the sand. Fill it up to 20mm-30mm away from the opening of the support plate. Step 6: Prepare the sealing material according to the powder-sand-liquid ratio of 3:2:1, and then seal and compact the 20mm-30mm space at the opening of the support plate to prevent the subsequent filling sand from leaking out. After the opening is sealed, let it dry for 6-8 hours. Step 7: After drying, proceed with the subsequent back layer operations and drying according to the normal coating process until the sealing layer coating is completed. Step 8: After the sealing layer has dried, use a cutting machine to cut off the end of the stainless steel pipe, ensuring that the cut end of the pipe is free of grout blockage and allows for smooth airflow. Step 9: Set the shell dewaxing temperature to 170-180℃, the pressure to 0.7-0.8MPa, the dewaxing time to 10-12min, and the pressure relief rate to 0.06-0.07MPa / min. After dewaxing, let it stand for 4-5 hours, and then bake it at high temperature.

2. The method for reducing cracking of deep and narrow structural shells of titanium alloy casings according to claim 1, characterized in that: In steps 3-5 and 8, the stainless steel tube can be replaced with a corundum tube.

3. A method for reducing cracking of deep and narrow structural shells of titanium alloy casings according to claim 1 or 2, characterized in that: The diameter d2 of the stainless steel or corundum tube is 6mm-10mm, and the total length is 30mm-40mm longer than the depth of the support plate.

4. The method for reducing cracking of deep and narrow structural shells of titanium alloy casings according to claim 1, characterized in that: The backing sand uses 16-60 mesh sand particles.

5. The method for reducing cracking of deep and narrow structural shells of titanium alloy casings according to claim 1, characterized in that: The diameter d2 of the stainless steel pipe is 6mm-10mm.

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