Low-cost and short-period titanium alloy casting preparation method

Abstract

The invention relates to a titanium alloy casting preparation method which comprises the steps that a three-dimensional model is transmitted to a 3D printer, and a 3D printing part is printed; the 3D printing part is soaked in a molten wax cylinder, and a wax-soaked 3D printing part model is obtained; the wax-impregnated 3D printing part model is immersed in yttrium oxide slurry, the surface of the model is evenly covered with a layer of yttrium oxide slurry, then a layer of yttrium oxide fine sand is scattered, and a first semi-finished product shell is obtained; immersing the first semi-finished product shell into the Shangjiang powder slurry, uniformly covering the surface of the first semi-finished product shell with a layer of Shangjiang powder slurry, and then scattering a layer of Shangjiang sand to obtain a second semi-finished product shell; heating to recover the paraffin, and burning to remove the 3D printing material to obtain a fourth semi-finished product shell; putting the fourth semi-finished product shell into a high-temperature roasting furnace to obtain a finished product ceramic shell; and the ceramic shell is assembled, preheated and then loaded into a vacuum consumable skull furnace, titanium alloy molten metal is vacuumized and melted, the molten metal is poured into the finished ceramic shell, and the titanium alloy casting is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy casting, and in particular to a method for preparing titanium alloy castings with low cost and short cycle. Background Art

[0002] Titanium alloy has excellent properties such as high specific strength, high heat resistance, and good corrosion resistance. It is a high-quality lightweight metal structural material and is widely used in aerospace, chemical, shipbuilding and other fields.

[0003] Casting is a common molding method for titanium alloy parts. Traditional titanium alloy casting methods are generally divided into investment casting and graphite casting. Both methods require the use of a vacuum consumable shell furnace for casting in a vacuum state. The main differences are as follows:

[0004] Before pouring, investment casting must first design and make a mold according to the product drawing, then press the paraffin model, apply slurry, remove the wax model, bake the shell, and obtain the ceramic shell for pouring. There are problems such as long mold manufacturing cycle, high cost, low wax mold strength when pressing large products, and easy deformation of finished castings.

[0005] Before pouring, graphite mold casting needs to design the graphite mold according to the product drawing, process the graphite mold, assemble the graphite mold, and obtain the graphite shell for pouring after vacuum degassing. The production cycle of graphite mold is lower than that of investment casting, but because most of the graphite molds are used once, there are problems such as high price, poor casting surface quality, and serious pollution on the production site.

[0006] With the acceleration of product replacement, casting products are gradually showing a trend of small batches and multiple varieties, and the requirements for product quality, cost and delivery cycle are becoming more and more stringent. The above two casting methods cannot meet the needs of small batches and multiple varieties of casting products. Therefore, a casting method with lower cost and faster production cycle is needed to realize the production of titanium alloy castings. Summary of the invention

[0007] In view of the shortcomings of the existing titanium alloy casting preparation technology, which has high cost and long cycle, the purpose of the present invention is to provide a low-cost and short-cycle preparation method for titanium alloy castings, so as to facilitate the economical preparation of high-quality titanium alloy castings.

[0008] The present application provides a method for preparing a titanium alloy casting, the method comprising:

[0009] Acquire a three-dimensional model corresponding to the titanium alloy casting, transmit the three-dimensional model to the 3D printer, and print out a 3D printed part corresponding to the three-dimensional model through the 3D printer;

[0010] The 3D printed part is immersed in a molten wax tank for 5 to 10 seconds, and then taken out and cooled to obtain a wax-immersed 3D printed part model;

[0011] Immersing the wax-impregnated 3D printed part model in yttrium oxide slurry, so that the surface of the model is evenly covered with a layer of yttrium oxide slurry, and then sprinkling a layer of yttrium oxide fine sand to obtain a first semi-finished shell;

[0012] Immersing the first semi-finished shell mold in the upper powder slurry, so that the surface of the first semi-finished shell mold is evenly covered with a layer of the upper powder slurry, and then sprinkling a layer of upper sand to obtain a second semi-finished shell mold;

[0013] Heating and recovering the paraffin of the second semi-finished shell mold, burning and removing the 3D printing material, and obtaining a hollow fourth semi-finished shell mold;

[0014] The fourth semi-finished shell mold is placed in a high-temperature baking furnace, heated to 1000-1100° C. for baking and vitrification, and cooled to obtain a finished ceramic shell mold;

[0015] The ceramic shell is assembled and preheated and then loaded into a vacuum consumable shell furnace, vacuumized, the titanium alloy liquid is melted, and the liquid metal is poured into the finished ceramic shell;

[0016] The mold is cooled out of the furnace and the shell is removed to obtain a titanium alloy casting.

[0017] Optionally, transferring the three-dimensional model to the 3D printer includes: selecting a reference plane of the three-dimensional model and adding support for 3D printing, converting the three-dimensional model into a file recognizable by the 3D printer, and then transferring the file recognizable by the 3D printer to the 3D printer.

[0018] Optionally, the 3D printer is a fused deposition modeling (FDM) printer, and the 3D printing raw material is polylactic acid (PLA).

[0019] Optionally, obtaining a three-dimensional model corresponding to the titanium alloy casting includes:

[0020] According to the casting drawing, use 3D drawing software to draw the 3D model of the casting;

[0021] The three-dimensional model of the casting is divided into n blocks according to the structure and size of the casting, and the divided three-dimensional model is determined as the three-dimensional model corresponding to the titanium alloy casting, where n is an integer greater than or equal to 2, or the three-dimensional model of the casting is determined as the three-dimensional model corresponding to the titanium alloy casting.

[0022] Optionally, immersing the 3D printed part into a molten wax bath comprises:

[0023] Remove support from the 3D printed part, trim burrs, and obtain n pieces of split part printing models or one piece of integral part printing model;

[0024] When n pieces of separate parts printing models are obtained, the n pieces of separate parts printing models are spliced ​​together with an adhesive to obtain an integral part printing model;

[0025] The integral part printing model is immersed in a molten wax bath.

[0026] Optionally, immersing the wax-impregnated 3D printed part model into yttrium oxide slurry comprises:

[0027] The wax-impregnated 3D printed part model is trimmed to remove excess wax and to smooth the surface flow marks to obtain a wax-impregnated 3D printed part model after surface quality optimization treatment;

[0028] The wax-immersed 3D printed part model after surface quality optimization is inspected for size and surface quality. After passing the inspection, auxiliary wax blocks such as runners, risers, and exhaust rods are bonded to the wax-immersed 3D printed part model to obtain a finished wax-immersed 3D printed part model;

[0029] The finished wax-impregnated 3D printed part model is immersed in yttrium oxide slurry.

[0030] Optionally, the wax-impregnated 3D printed part model is immersed in yttrium oxide slurry, so that the surface of the model is evenly covered with a layer of yttrium oxide slurry, and then a layer of yttrium oxide fine sand is sprinkled to obtain a first semi-finished shell, including:

[0031] The wax-impregnated 3D printed part model is immersed in yttrium oxide slurry, so that the surface of the model is evenly covered with a layer of yttrium oxide slurry, and then a layer of yttrium oxide fine sand is sprinkled, and it is transferred to a constant temperature and humidity room. After ventilation and drying for 24 hours, the dried model is immersed in yttrium oxide slurry again, and the surface of the model is evenly covered with a layer of yttrium oxide slurry again, and then a layer of zirconium oxide fine sand is sprinkled, and it is transferred to a constant temperature and humidity room. After drying for 24 hours, the first semi-finished shell is obtained.

[0032] Optionally, the step of immersing the first semi-finished shell mold in a powder slurry so that a layer of the powder slurry is evenly covered on the surface of the first semi-finished shell mold, and then sprinkling a layer of powder sand to obtain a second semi-finished shell mold comprises:

[0033] Immerse the first semi-finished mold shell in the shop powder slurry to evenly cover the surface of the first semi-finished mold shell with a layer of shop powder slurry, then sprinkle a layer of shop sand, transfer to a constant temperature and humidity room, ventilate and dry for 8 to 24 hours, repeat this step 5 to 10 times according to the weight and size of the model to obtain a second semi-finished mold shell.

[0034] Optionally, the heating and recycling of the paraffin of the second semi-finished shell mold and the burning and removal of the 3D printing material to obtain a hollow fourth semi-finished shell mold include:

[0035] The surface of the mold shell at the pouring gate, riser, and vent hole of the second semi-finished mold shell is cut off to expose the wax-impregnated 3D printed part model body at the above-mentioned parts, so as to obtain a third semi-finished mold shell;

[0036] The third semi-finished shell mold is placed downwardly into a special furnace for removal, where the portion of the shell mold that leaks out of the wax-impregnated 3D printed part model body is heated to recover the paraffin and burn to remove the PLA, thereby obtaining a hollow fourth semi-finished shell mold.

[0037] Optionally, removing the mold shell to obtain the titanium alloy casting comprises:

[0038] The titanium alloy casting is obtained after removing the mold shell, cutting off the runner and riser, grinding, repair welding and sand blasting.

[0039] The present application also provides a method for preparing a titanium alloy casting, comprising the following steps:

[0040] Step 1: According to the casting drawing, use Solidworks, UG and other software to draw the 3D model of the casting, and divide the 3D model into several blocks according to the structure and size of the casting. If the 3D model is small or the structure is simple, the model can be left undivided and can be directly transferred to step 2.

[0041] Step 2: Use special software to select the reference surface and add support to the 3D model or the whole model segmented in step 1, and convert the 3D model into a file that can be recognized by the 3D printer, and then transfer it to the 3D printer to print the 3D model. Here, the 3D printer is required to be an FDM (fused deposition modeling) printer, and the raw material for 3D printing is PLA (polylactic acid).

[0042] Step 3: Remove the support from the PLA 3D model printed in step 2, trim the burrs, and obtain several separate parts PLA models.

[0043] Step 4: Splice the separate PLA models obtained in step 3 together with a special adhesive to obtain a complete PLA model of parts. The overall printed model can be directly transferred to step 5.

[0044] Step 5: Immerse the complete part PLA model obtained in step 4 into the molten wax tank as a whole, maintain it for 5 to 10 seconds, and then take it out and let it cool.

[0045] Step 6: trim the wax-impregnated PLA model obtained in step 5, remove excess wax, and smooth the surface flow marks to obtain a PLA-paraffin composite investment mold with excellent surface quality. The execution order of steps 4, 5, and 6 can be adjusted according to the complexity of the casting structure.

[0046] Step 7: The PLA-paraffin composite investment pattern obtained in step 6 is inspected for size and surface quality. After passing the inspection, auxiliary wax blocks such as runners, risers, and exhaust rods are bonded to the PLA-paraffin composite investment pattern to obtain a finished PLA-paraffin composite investment pattern.

[0047] Step 8: Making a surface layer, immersing the finished PLA-paraffin composite investment mold obtained in step 7 into the yttrium oxide slurry as a whole, so that the surface of the model is evenly covered with a layer of yttrium oxide slurry, and then sprinkled with a layer of yttrium oxide fine sand; transferring to a constant temperature and humidity room, ventilating and drying for 24 hours, and then immersing the dried model in the yttrium oxide slurry, the surface of the model is evenly covered with a layer of yttrium oxide slurry again, and then sprinkled with a layer of zirconium oxide fine sand, and transferred to a constant temperature and humidity room, and dried for 24 hours to obtain a semi-finished shell 1;

[0048] Step nine: Make a reinforcement layer. Immerse the semi-finished shell obtained in step eight in the shop powder slurry, so that the surface of the semi-finished shell is evenly covered with a layer of shop powder slurry, and then sprinkle a layer of shop sand, transfer to a constant temperature and humidity room, ventilate and dry for 8 to 24 hours, repeat step eight 5 to 10 times according to the weight and size of the model to obtain a semi-finished shell 2.

[0049] Step 10: The semi-finished shell mold 2 obtained in step 9 is cut off from the surface of the shell mold such as the runner, riser, and vent hole to expose the PLA-paraffin composite investment mold body in the above-mentioned parts to obtain a semi-finished shell mold 3.

[0050] Step 11: Place the semi-finished shell mold 3 obtained in step 10 with the part of the PLA-paraffin composite investment mold body leaking out downward into a special furnace for removing the PLA-paraffin composite investment mold, heat to recover the paraffin, burn to remove the PLA, and obtain a hollow semi-finished shell mold 4.

[0051] Step 12: Place the semi-finished shell mold 4 obtained in step 11 into a high-temperature baking furnace, heat it to 1000-1100° C. to bake it for vitrification, and obtain a finished ceramic shell mold after cooling.

[0052] Step 13: Assemble the ceramic shell obtained in step 12, preheat and place it into a vacuum consumable shell furnace, evacuate the vacuum, melt the titanium alloy molten metal, and pour the molten metal into the finished ceramic shell.

[0053] Step 14: Cool down and take out of the furnace, remove the mold shell, cut off the runner and riser, grind, repair weld, and sandblast to obtain the titanium alloy casting.

[0054] Beneficial effects of the present invention:

[0055] 1) Compared with the traditional investment casting process using paraffin wax pressed models, the present invention saves the cost and cycle of making molds, and the printed PLA model has high strength, which can effectively avoid deformation during the shell production process and save the later correction cycle and cost.

[0056] 2) The device used for printing the three-dimensional model of the present invention is an FDM printer, which has a low procurement cost. The raw material for printing, polylactic acid (PLA), is also inexpensive and a biodegradable material. The products after full combustion are H2O and CO2, which are pollution-free to the environment.

[0057] 3) Compared with the traditional graphite mold casting process, the present invention saves the time of making graphite molds, does not require expensive vacuum degassing equipment, has a much lower manufacturing cost than graphite molds, and has no graphite dust pollution at the production site.

[0058] 4) After the FDM printers are deployed on a scale of hundreds, the present invention can shorten the production cycle of titanium alloy castings from the traditional 60 to 70 days to 25 to 35 days, and is particularly suitable for the production of small batch, multi-variety, and large-size casting products. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 Schematic diagram of a three-dimensional model of an impeller casting and a model with added supports according to Embodiment 1 of the present invention.

[0060] Figure 2 It is a schematic diagram of a three-dimensional model of a pump body casting and a model with added support according to the second embodiment of the present invention.

[0061] Figure 3 It is a schematic diagram of a three-dimensional model of a push-pull ring casting and a model with added support according to the third embodiment of the present invention.

[0062] Figure 4 Schematic diagram of a three-dimensional model of a medical bone support casting and a model with added support according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0063] The content of the present invention is described in more detail below in conjunction with the embodiments. It should be noted that the following embodiments are only representative examples of the present invention. Obviously, the technical solution of the present invention is not limited to the following embodiments, and there are also many variations. All variations directly derived or associated from the content disclosed in the present invention should be considered as the protection scope of the present invention.

[0064] In the present invention, unless otherwise specified, all parts and percentages are by weight, and all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments are conventional methods in the art unless otherwise specified.

[0065] Embodiment 1

[0066] Taking the production of a closed impeller casting as an example, the maximum outer diameter of the casting is about 400mm, the maximum height is about 150mm, and the flow channel width is 25mm. The preparation steps are as follows:

[0067] Step 1: According to the casting drawing, use Solidworks software to draw the closed impeller 3D model, and split the impeller model into two lobes from the middle, and save them as two independent sldprt format files. Figure 1-1 .

[0068] Step 2: Use the dedicated software to set the printing base surface and add support for the two sldprt files obtained in step 1, and then convert the sldprt files into stl files that can be recognized by the 3D printer. Then copy the two stl files to two FDM 3D printers respectively, load the PLA raw material, and start printing the impeller 3D model at the same time. After printing, you will get the impeller model with two PLA materials. One of the impeller models with support added is shown in Figure 1-2 .

[0069] Step 3: Remove the support and trim the burrs from the impeller model obtained in step 2 to obtain a two-lobed impeller PLA model.

[0070] Step 4: Splice the two-lobed impeller PLA model obtained in step 3 together with a special adhesive to obtain a complete impeller PLA model.

[0071] Step 5: Immerse the impeller PLA model obtained in step 4 into the molten wax tank as a whole, maintain it for 5 to 10 seconds, and then take it out and let it cool.

[0072] Step 6: trim the wax-impregnated impeller PLA model obtained in step 5, remove excess wax, and repair and smooth the surface flow marks to obtain an impeller PLA-paraffin composite investment mold with excellent surface quality.

[0073] Step 7: The impeller PLA-paraffin composite investment mold obtained in step 6 is inspected for size and surface quality. After passing the inspection, auxiliary wax blocks such as sprue, riser, exhaust rod, etc. are glued to the impeller PLA-paraffin composite investment mold to obtain a finished impeller PLA-paraffin composite investment mold.

[0074] Step 8: Making a surface layer, immersing the finished impeller PLA-paraffin composite investment mold obtained in step 7 into the yttrium oxide slurry as a whole, so that the surface of the model is evenly covered with a layer of yttrium oxide slurry, and then sprinkle a layer of yttrium oxide fine sand; transferring to a constant temperature and humidity room, ventilating and drying for 24 hours, and then immersing the dried impeller model in the yttrium oxide slurry, so that the surface of the impeller model is evenly covered with a layer of yttrium oxide slurry again, and then sprinkle a layer of zirconium oxide fine sand, and transferring to a constant temperature and humidity room for ventilation and drying for 24 hours to obtain a semi-finished impeller shell 1;

[0075] Step 9: Make a reinforcement layer, immerse the semi-finished impeller shell 1 obtained in step 8 into the upper powder slurry, so that the surface of the semi-finished impeller shell is evenly covered with a layer of upper powder slurry, and then sprinkle a layer of upper sand, transfer to a constant temperature and humidity room, ventilate and dry for 12 hours. Repeat the above step 9 6 times to obtain a semi-finished shell 2.

[0076] Step 10: The semi-finished impeller shell 2 obtained in step 9 is cut off from the surface of the shell such as the runner, riser, exhaust hole, etc., to expose the PLA-paraffin composite investment mold body in the above-mentioned parts, and obtain the semi-finished impeller shell 3.

[0077] Step 11: Place the semi-finished impeller shell 3 obtained in step 10 with the part of the PLA-paraffin composite investment mold body leaking out downward into a special furnace for removing the PLA-paraffin composite investment mold, heat to recover the paraffin, burn to remove the PLA, and obtain a hollow semi-finished impeller shell 4.

[0078] Step 12: Place the semi-finished impeller shell 4 obtained in step 11 into a high-temperature sintering furnace, heat it to 1000° C. to sinter it for vitrification, and obtain a finished impeller ceramic shell after cooling.

[0079] Step 13: Assemble the impeller ceramic shell obtained in step 12, preheat and load it into a vacuum consumable shell furnace, evacuate the vacuum, melt the titanium alloy molten metal, and pour the molten metal into the impeller ceramic shell.

[0080] Step 14: Cool down and take out of the furnace, remove the mold shell, cut off the runner and riser, grind, repair weld, and sandblast to obtain the titanium alloy impeller casting.

[0081] Example 2

[0082] Taking the production of a pump body casting as an example, the maximum outline size of the casting is about 800mm and the maximum thickness is about 300mm. The preparation steps are as follows:

[0083] Step 1: According to the casting drawing, use Solidworks software to draw the 3D model of the pump body, and divide the pump body model into 5 pieces and save them as 5 independent sldprt format files. Figure 2-1 .

[0084] Step 2: Use the dedicated software to set the printing base surface and add support for the 5 sldprt files obtained in step 1, then convert the sldprt files into stl files that can be recognized by the 3D printer, and then copy the 5 stl files to 5 FDM 3D printers respectively, and start printing the pump body 3D model at the same time after loading the PLA raw material. After printing, 5 separate pump body models made of PLA material are obtained. One of the pump body models with support added is shown in Figure 2-2 .

[0085] Step 3: Remove supports and trim burrs from the 5 PLA pump body models obtained in step 2 to obtain 8 split pump body PLA models.

[0086] Step 4: Immerse the five separate pump body PLA models obtained in step 3 into the molten wax tank respectively, maintain for 5 to 10 seconds, and then take them out and cool them down.

[0087] Step 5: trim the 5 wax-impregnated split pump body PLA models obtained in step 4, remove excess wax, and repair and smooth the surface flow marks to obtain a split pump body PLA-paraffin composite investment mold with excellent surface quality.

[0088] Step 6: Splice the 5 separate pump body PLA-paraffin composite melt patterns obtained in step 5 together with a special adhesive, and repair and smooth the spliced ​​parts with melted wax to obtain a complete pump body PLA-paraffin composite melt pattern.

[0089] Step 7: Perform size and surface quality inspection on the pump body PLA-paraffin composite investment mold obtained in step 6. After passing the inspection, glue auxiliary wax blocks such as sprue, riser, exhaust rod, etc. on the pump body PLA-paraffin composite investment mold to obtain a finished pump body PLA-paraffin composite investment mold.

[0090] Step 8: Making the surface layer, immersing the finished pump body PLA-paraffin composite investment mold obtained in step 7 into the yttrium oxide slurry as a whole, so that the surface of the model is evenly covered with a layer of yttrium oxide slurry, and then sprinkle a layer of yttrium oxide fine sand; transferring to a constant temperature and humidity room, ventilating and drying for 24 hours, and then immersing the dried pump body model in the yttrium oxide slurry, so that the surface of the pump body model is evenly covered with a layer of yttrium oxide slurry again, and then sprinkle a layer of zirconium oxide fine sand, and transferring to a constant temperature and humidity room, drying for 24 hours, to obtain a semi-finished pump body shell 1;

[0091] Step 9: Make a reinforcement layer, immerse the semi-finished pump shell 1 obtained in step 8 into the shop powder slurry, so that the surface of the semi-finished pump shell is evenly covered with a layer of shop powder slurry, and then sprinkle a layer of shop sand, transfer to a constant temperature and humidity room, ventilate and dry for 24 hours. Repeat the above step 9 10 times to obtain a semi-finished pump shell 2.

[0092] Step 10: Cut off the surface of the semi-finished pump body shell 2 obtained in step 9 at the pouring gate, riser, exhaust hole and other parts to expose the PLA-paraffin composite investment mold body at the above parts to obtain a semi-finished pump body shell 3.

[0093] Step 11: Place the semi-finished pump body mold shell 3 obtained in step 10 with the part of the PLA-paraffin composite investment mold body leaking out downward into a special furnace for removing the PLA-paraffin composite investment mold, heat to recover the paraffin, burn to remove the PLA, and obtain a hollow semi-finished pump body mold shell 4.

[0094] Step 11: Put the pump body shell 4 obtained in step 11 into a high-temperature baking furnace, heat it to 1100° C. to bake it for vitrification, and obtain a finished pump body ceramic shell after cooling.

[0095] Step 12: Assemble the ceramic shell of the pump body obtained in step 12, preheat and place it into a vacuum consumable shell furnace, evacuate the vacuum, melt the titanium alloy molten metal, and pour the molten metal into the ceramic shell of the pump body.

[0096] Step 13: Cool down and take out of the furnace, remove the mold shell, cut off the runner and riser, grind, repair weld, and sandblast to obtain the titanium alloy pump body casting.

[0097] Example 3

[0098] Taking the production of a push-pull ring casting as an example, the maximum outline size of the casting is about Φ600mm and the height is about 450mm. The preparation steps are as follows:

[0099] Step 1: According to the casting drawing, use Solidworks software to draw the push-pull ring 3D model, and divide the push-pull ring model into 4 pieces and save them as 4 independent sldprt format files. Figure 3-1 .

[0100] Step 2: Use the dedicated software to set the printing base surface and add support for the 4 sldprt files obtained in step 1, and then convert the sldprt files into stl files that can be recognized by the 3D printer. Then copy the 4 stl files to 4 FDM 3D printers respectively, load the PLA raw materials, and start printing the push-pull ring 3D model at the same time. After printing, you will get 4 separate push-pull ring models made of PLA. One of the models with added support is shown in Figure 3-2 .

[0101] Step 3: Remove the supports from the four split push-pull ring models obtained in step 2, trim the burrs, and obtain four split push-pull ring PLA models.

[0102] Step 4: Splice the four separate push-pull ring PLA models obtained in step 3 together with a special adhesive to obtain a complete push-pull ring PLA model.

[0103] Step 5: Immerse the entire push-pull ring PLA model obtained in step 4 into the molten wax tank, maintain for 5 to 10 seconds, and then take it out and cool it down.

[0104] Step 6: trim the wax-impregnated push-pull ring PLA model obtained in step 5, remove excess wax, and repair and smooth the surface flow marks to obtain a push-pull ring PLA-paraffin composite investment pattern with excellent surface quality.

[0105] Step 7: The push-pull ring PLA-paraffin composite investment pattern obtained in step 6 is inspected for size and surface quality. After passing the inspection, auxiliary wax blocks such as runners, risers, and exhaust rods are glued to the push-pull ring PLA-paraffin composite investment pattern to obtain a finished push-pull ring PLA-paraffin composite investment pattern.

[0106] Step 8: Make the surface layer, immerse the finished push-pull ring PLA-paraffin composite investment mold obtained in step 7 into the yttrium oxide slurry as a whole, so that the surface of the model is evenly covered with a layer of yttrium oxide slurry, and then sprinkle a layer of yttrium oxide fine sand; transfer to a constant temperature and humidity room, ventilate and dry for 24 hours, then immerse the dried push-pull ring model in the yttrium oxide slurry, so that the surface of the push-pull ring model is evenly covered with a layer of yttrium oxide slurry again, and then sprinkle a layer of zirconium oxide fine sand, transfer to a constant temperature and humidity room, and dry for 24 hours to obtain a semi-finished push-pull ring shell 1;

[0107] Step 9: Make a reinforcement layer, immerse the semi-finished push-pull ring shell 1 obtained in step 8 into the upper shop powder slurry, so that the surface of the semi-finished push-pull ring shell is evenly covered with a layer of upper shop powder slurry, and then sprinkle a layer of upper shop sand, transfer to a constant temperature and humidity room, ventilate and dry for 8 to 24 hours. Repeat the above step nine 8 times to obtain a semi-finished push-pull ring shell 2.

[0108] Step 10: Cut off the mold shell on the surface of the runner, riser, vent and other parts of the semi-finished push-pull ring shell 2 obtained in step 9 to expose the PLA-paraffin composite investment mold body in the above parts to obtain a semi-finished push-pull ring shell 3.

[0109] Step 11: Place the semi-finished push-pull ring shell 3 obtained in step 10 with the part leaking out of the PLA-paraffin composite investment mold body facing downward into a special furnace for removing the PLA-paraffin composite investment mold, heat to recover the paraffin, burn to remove the PLA, and obtain a hollow semi-finished push-pull ring shell 4.

[0110] Step 12: Place the push-pull ring shell 4 obtained in step 11 into a high-temperature baking furnace, bake at 1100° C. to obtain a finished push-pull ring ceramic shell after cooling.

[0111] Step 13: Assemble the pump body ceramic shell obtained in step 12, preheat and place it into a vacuum consumable shell furnace, evacuate the vacuum, melt the titanium alloy liquid, and pour it into the pump body ceramic shell.

[0112] Step 14: Cool down and take out of the furnace, remove the mold shell, cut off the runner and riser, grind, repair weld, and sandblast to obtain the titanium alloy push-pull ring casting.

[0113] Example 4

[0114] Taking the production of a titanium alloy medical bone tray casting as an example, the outer contour size of the casting is about 80×40mm and the height is about 50mm. The preparation steps are as follows:

[0115] Step 1: According to the casting drawing, use Solidworks software to draw the 3D model of the bone tray and save it as a sldprt format file. Figure 4-1 .

[0116] Step 2: Use the dedicated software to set the printing reference surface and add supports for the sldprt file obtained in step 1, and then copy 12 copies on the same reference surface. Convert the sldprt file into an stl file recognizable by the 3D printer to obtain an stl file containing 12 bone tray product models. Then copy the stl file to an FDM 3D printer, load the PLA raw material, and start printing the bone tray 3D model. After printing, you will get 12 PLA bone tray models. See the 12 bone tray models with supports added. Figure 4-2 .

[0117] Step 3: Remove the support from the PLA bone support model obtained in step 2, trim the burrs, and obtain 12 bone support PLA models.

[0118] Step 4: The printed bone support model is a whole model, so this step can be omitted.

[0119] Step 5: Immerse the 12 bone tray PLA models obtained in step 3 into the molten wax tank for 5 to 10 seconds, then take them out and let them cool.

[0120] Step 6: The 12 wax-immersed bone tray PLA models obtained in step 5 are trimmed to remove excess wax and to smooth the surface flow marks to obtain bone tray PLA-paraffin composite investment patterns with excellent surface quality.

[0121] Step 7: The 12 bone trays PLA-paraffin composite investment patterns obtained in step 6 are inspected for size and surface quality. If they pass the inspection, wax blocks such as risers and exhaust rods are glued to the 12 bone trays PLA-paraffin composite investment patterns respectively, and then glued to a runner wax rod to obtain a finished PLA-paraffin composite investment pattern assembly containing 12 bone trays.

[0122] Step 8: Making a surface layer, immersing the finished PLA-paraffin composite investment pattern assembly of the bone tray obtained in step 7 into yttrium oxide slurry, so that the surface of the model is evenly covered with a layer of yttrium oxide slurry, and then sprinkle a layer of yttrium oxide fine sand; transferring to a constant temperature and humidity room, ventilating and drying for 24 hours, and then immersing the dried bone tray model in yttrium oxide slurry, so that the surface of the bone tray model is evenly covered with a layer of yttrium oxide slurry again, and then sprinkle a layer of zirconium oxide fine sand, transferring to a constant temperature and humidity room, drying for 24 hours, and obtaining a semi-finished bone tray assembly shell 1;

[0123] Step 9: Make a reinforcement layer, immerse the semi-finished bone support assembly shell 1 obtained in step 8 into the shop powder slurry, so that the surface of the semi-finished bone support assembly shell is evenly covered with a layer of shop powder slurry, and then sprinkle a layer of shop sand, transfer to a constant temperature and humidity room, and ventilate and dry for 8 to 24 hours. Repeat the above step 8 5 times to obtain a semi-finished bone support assembly shell 2.

[0124] Step 10: Cut off the surface of the semi-finished bone tray assembly shell 2 obtained in step 9 at the pouring gate, riser, vent hole and other parts to expose the PLA-paraffin composite investment mold body at the above parts to obtain a semi-finished bone tray assembly shell 3.

[0125] Step 11: Place the semi-finished bone support assembly shell 3 obtained in step 10 with the part of the PLA-paraffin composite investment mold body leaking out downward into a special furnace for removing the PLA-paraffin composite investment mold, heat to recover the paraffin, burn to remove the PLA, and obtain a hollow semi-finished bone support assembly shell 4.

[0126] Step 12: Place the semi-finished bone tray assembly shell 4 obtained in step 11 into a high-temperature baking furnace, bake at 1000° C. to vitrify, and obtain a finished bone tray assembly ceramic shell after cooling.

[0127] Step 13: Assemble the ceramic shell mold of the bone tray assembly obtained in step 12, preheat it and place it into a vacuum consumable shell solidification furnace, evacuate the vacuum, melt the titanium alloy molten metal, and pour the molten metal into the ceramic shell mold of the bone tray assembly.

[0128] Step 14: After cooling and taking out of the furnace, removing the mold shell, cutting off the runner and riser, splitting, grinding, repair welding, and sandblasting, 12 titanium alloy bone support castings are obtained.

[0129] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0130] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a titanium alloy casting, characterized in that: The method comprises: Acquire a three-dimensional model corresponding to the titanium alloy casting, transmit the three-dimensional model to the 3D printer, and print out a 3D printed part corresponding to the three-dimensional model through the 3D printer; The 3D printed part is immersed in a molten wax tank for 5 to 10 seconds, and then taken out and cooled to obtain a wax-immersed 3D printed part model; Immersing the wax-impregnated 3D printed part model in yttrium oxide slurry, so that the surface of the model is evenly covered with a layer of yttrium oxide slurry, and then sprinkling a layer of yttrium oxide fine sand to obtain a first semi-finished shell; Immersing the first semi-finished shell mold in the upper powder slurry, so that the surface of the first semi-finished shell mold is evenly covered with a layer of the upper powder slurry, and then sprinkling a layer of upper sand to obtain a second semi-finished shell mold; Heating and recovering the paraffin of the second semi-finished shell mold, burning and removing the 3D printing material, and obtaining a hollow fourth semi-finished shell mold; The fourth semi-finished shell mold is placed in a high-temperature baking furnace, heated to 1000-1100° C. for baking and vitrification, and cooled to obtain a finished ceramic shell mold; The ceramic shell is assembled and preheated and then loaded into a vacuum consumable shell furnace, vacuumized, the titanium alloy liquid is melted, and the liquid metal is poured into the finished ceramic shell; The mold is cooled out of the furnace and the shell is removed to obtain a titanium alloy casting.

2. The method for preparing a titanium alloy casting according to claim 1, characterized in that: The three-dimensional model is transferred to the 3D printer, including: selecting a reference surface of the three-dimensional model and adding support for 3D printing, converting the three-dimensional model into a file recognizable by the 3D printer, and then transferring the file recognizable by the 3D printer to the 3D printer.

3. The method for preparing a titanium alloy casting according to claim 2, characterized in that: The 3D printer is a fused deposition modeling 3D printer, and the 3D printing raw material is polylactic acid.

4. The method for preparing a titanium alloy casting according to claim 3, characterized in that: The step of obtaining a three-dimensional model corresponding to the titanium alloy casting comprises: According to the casting drawing, use 3D drawing software to draw the 3D model of the casting; The three-dimensional model of the casting is divided into n blocks according to the structure and size of the casting, and the divided three-dimensional model is determined as the three-dimensional model corresponding to the titanium alloy casting, where n is an integer greater than or equal to 2, or the three-dimensional model of the casting is determined as the three-dimensional model corresponding to the titanium alloy casting.

5. The method for preparing a titanium alloy casting according to claim 4, characterized in that: The step of immersing the 3D printed part into a molten wax tank comprises: Remove support from the 3D printed part, trim burrs, and obtain n pieces of split part printing models or one piece of integral part printing model; When n pieces of separate parts printing models are obtained, the n pieces of separate parts printing models are spliced ​​together with an adhesive to obtain an integral part printing model; The integral part printing model is immersed in a molten wax bath.

6. The method for preparing a titanium alloy casting according to claim 4, characterized in that: The wax-impregnated 3D printed part model is immersed in yttrium oxide slurry, comprising: The wax-impregnated 3D printed part model is trimmed to remove excess wax and to smooth the surface flow marks to obtain a wax-impregnated 3D printed part model after surface quality optimization treatment; The wax-immersed 3D printed part model after surface quality optimization is inspected for size and surface quality. After passing the inspection, a sprue, a riser, and a vent rod are bonded to the wax-immersed 3D printed part model to obtain a finished wax-immersed 3D printed part model; The finished wax-impregnated 3D printed part model is immersed in yttrium oxide slurry.

7. The method for preparing a titanium alloy casting according to claim 1, characterized in that: The wax-impregnated 3D printed part model is immersed in yttrium oxide slurry, so that the surface of the model is evenly covered with a layer of yttrium oxide slurry, and then a layer of yttrium oxide fine sand is sprinkled to obtain a first semi-finished shell, including: The wax-impregnated 3D printed part model is immersed in yttrium oxide slurry, so that the surface of the model is evenly covered with a layer of yttrium oxide slurry, and then a layer of yttrium oxide fine sand is sprinkled, and it is transferred to a constant temperature and humidity room. After ventilation and drying for 24 hours, the dried model is immersed in yttrium oxide slurry again, and the surface of the model is evenly covered with a layer of yttrium oxide slurry again, and then a layer of zirconium oxide fine sand is sprinkled, and it is transferred to a constant temperature and humidity room. After drying for 24 hours, the first semi-finished shell is obtained.

8. The method for preparing a titanium alloy casting according to claim 1, characterized in that: The step of immersing the first semi-finished shell mold into the upper powder slurry so that the surface of the first semi-finished shell mold is evenly covered with a layer of the upper powder slurry, and then sprinkling a layer of upper sand to obtain a second semi-finished shell mold comprises: Immerse the first semi-finished mold shell in the shop powder slurry to evenly cover the surface of the first semi-finished mold shell with a layer of shop powder slurry, then sprinkle a layer of shop sand, transfer to a constant temperature and humidity room, ventilate and dry for 8 to 24 hours, repeat this step 5 to 10 times according to the weight and size of the model to obtain a second semi-finished mold shell.

9. The method for preparing a titanium alloy casting according to claim 6, characterized in that: The paraffin of the second semi-finished shell is recovered by heating, and the 3D printing material is removed by burning to obtain a hollow fourth semi-finished shell, comprising: The surface of the mold shell at the pouring gate, riser, and vent hole of the second semi-finished mold shell is cut off to expose the wax-impregnated 3D printed part model body at the above-mentioned parts, so as to obtain a third semi-finished mold shell; The third semi-finished shell mold is placed downwardly into a special furnace for removal, where the portion of the shell mold leaking out of the wax-impregnated 3D printed part model body is heated to recover the paraffin wax and burn to remove the PLA, thereby obtaining a hollow fourth semi-finished shell mold; The fourth semi-finished shell is placed in a high-temperature baking furnace, heated to 1000-1100° C. for baking and vitrification, and cooled to obtain a finished ceramic shell. The ceramic shell is preheated and placed in a vacuum consumable shell furnace to evacuate the vacuum, melt the titanium alloy molten metal, and then pour the molten metal into the finished ceramic shell.

10. The method for preparing a titanium alloy casting according to claim 6, characterized in that: Remove the shell to obtain titanium alloy castings, including: The titanium alloy casting is obtained after removing the mold shell, cutting off the runner and riser, grinding, repair welding and sand blasting.

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