Preparation method of casting with complex pipe cavity and mold

Abstract

The invention relates to the technical field of metal casting, in particular to a preparation method of a casting with a complex pipe cavity and a mold, and the preparation method comprises the steps of mold core preparation, wax mold design, basic wax mold preparation, integral wax mold preparation, mold shell preparation and smelting and pouring. The basic wax mold preparation comprises the step of designing a plurality of block wax molds according to a casting pipe cavity structure; the whole wax mold preparation comprises the steps that a mold core and a plurality of block wax molds are combined and assembled through a splicing tool, so that the mold core is arranged in a multi-angle special-shaped pipe cavity defined by the block wax molds, and a whole wax mold is obtained; wherein partial areas of at least partial pipe bodies of the mold core are the same as the inner diameter of the multi-angle special-shaped pipe cavities in the corresponding positions so as to be precisely matched, and the rest partial areas of at least partial pipe bodies are arranged in the multi-angle special-shaped pipe cavities in a suspended mode. By means of the preparation method, it can be guaranteed that the block wax mold is accurately matched with the mold core, and the size precision of an inner cavity of a later casting can be guaranteed through the size precision of the mold core.

Description

Technical Field

[0001] The invention relates to the technical field of metal casting, and in particular to a method for preparing a casting with a complex lumen and a mold. Background Art

[0002] Titanium alloy precision castings are widely used in aviation, aerospace, weapons, and shipbuilding. Due to the requirements of their use environment, the quality of castings is required to be high. They are usually prepared by investment casting, which is also called lost wax casting. It usually refers to the use of fusible materials to make casting patterns, and several layers of refractory materials are coated on the surface of the pattern to make a shell. The pattern is melted and discharged from the shell, and the shell is obtained after high-temperature roasting. The casting is obtained by pouring molten metal into the shell, which generally includes wax pressing, shell preparation, dewaxing, pouring molten metal, and post-processing. Therefore, the quality of titanium alloy shell has an important influence on the molding of titanium alloy castings.

[0003] For titanium alloy precision castings, due to the need for unified structure and function, the internal structure is complex and often contains blind cavity structures. Ceramic cores are required to form complex inner cavities. After the casting is poured, the cores are removed to form the inner cavity structure of the casting. Therefore, during the wax pressing process of the casting, it is necessary to place the core in the wax pressing mold and then inject wax to form a wax mold with a core. For castings with complex inner cavities, it is usually necessary to prepare block wax molds in different areas and then splice them into an integral wax mold. Since the integral wax mold is spliced ​​together by multiple parts, when the block wax mold and the multi-angle tubular core are matched, due to the problem of manufacturing dimensional accuracy between the block wax mold and the core, assembly dislocation is prone to occur during splicing, resulting in the inability of the block wax mold to be accurately assembled with the core, thereby affecting the dimensional accuracy of the casting. For wax molds with cores inside, during the wax pressing process, they are easily impacted by the wax liquid, causing the core to shift and break. At the same time, since the shell needs to be made through high-temperature baking, the high-temperature baking process has a certain impact on the core. For the shell with a core inside, after dewaxing, the core is only connected to the shell by the fixed end, and the rest is a suspended structure. During high-temperature baking, it is prone to cracking or deviation due to thermal expansion and contraction. The baking process needs to be controlled to stabilize the quality of the shell and core.

[0004] For core removal, there may be cases where the core is not removed completely or the inner wall of the casting is damaged. Since the casting is prepared by the shell and finally formed after the core is removed, the above processes have an impact on the overall forming, dimensional accuracy and inner cavity quality of the casting, seriously affecting the reliability of the casting.

[0005] Therefore, the present invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide a method and mold for preparing a casting with a complex tubular cavity. In the preparation method, multiple tube bodies distributed at multiple angles of a core are used to form a multi-dimensional matching relationship with a block wax mold, which not only ensures the precise matching of the block wax mold and the core, but also can use the dimensional accuracy of the core to ensure the dimensional accuracy of the inner cavity of the later casting.

[0007] In order to achieve the above object, the present invention provides a method for preparing a casting with a complex lumen, comprising the following steps:

[0008] Prepare a core according to the shape of the casting tube cavity, wherein the core includes a plurality of tube bodies distributed at multiple angles;

[0009] Design multiple wax molds according to the casting lumen structure;

[0010] The core is assembled with the plurality of the divided wax models by using a splicing tool to form an integral wax model with a multi-angle special-shaped lumen, and the core is placed in the multi-angle special-shaped lumen; wherein at least a portion of the tubular body of the core has the same inner diameter as the multi-angle special-shaped lumen at the corresponding position for precise matching, and the remaining portion is suspended in the multi-angle special-shaped lumen;

[0011] The surface of the integral wax mold is coated with slurry, dried, dewaxed and fired to form a casting shell;

[0012] The casting shell is melted and poured, and then the internal core is removed to obtain the casting.

[0013] In a specific embodiment of the present invention, melting and pouring the casting wax pattern to obtain the casting comprises:

[0014] Using the casting shell to cast the casting to obtain a casting with a core;

[0015] The core inside the casting is removed to obtain a casting with a multi-angle lumen.

[0016] In a specific embodiment of the present invention, the core in the casting is removed by vibration and grinding.

[0017] In a specific embodiment of the present invention, the mold shell is preheated before pouring, and the preheating temperature is between 300-500°C.

[0018] In a specific embodiment of the present invention, the slurry is coated on the surface of the integral wax mold, and after drying, the shell is formed, which comprises:

[0019] Preparation of surface shell: coating the surface of the integral wax mold with surface slurry, and then removing excess surface slurry;

[0020] The integral wax mold is subjected to surface sanding, and after drying, a surface shell is formed;

[0021] Preparation of back layer shell: coating the surface of the surface shell with back layer slurry and removing excess back layer slurry; then performing back layer sanding and drying to form a back layer shell;

[0022] The back layer shell preparation steps are repeated multiple times to form a multi-layer back layer shell.

[0023] In a specific embodiment of the present invention, the shell dewaxing comprises:

[0024] After heating to the dewaxing temperature, keep the temperature until the wax liquid flows out from the dewaxing port, and then cool the shell to room temperature along with the furnace;

[0025] Preferably, the dewaxing temperature is 100-250° C., and the holding time is 3-8 hours; preferably, the wax liquid flows out from the wax outlet in the middle or on the side of the bottom area of ​​the shell.

[0026] In a specific embodiment of the present invention, the shell calcination comprises:

[0027] After heating to the first, second and third roasting temperatures, keep them warm respectively, and then cool them down and take them out of the furnace;

[0028] Preferably, the first calcination temperature is 500-600°C, and the holding time is ≥3h; the holding time is preferably 3-6h;

[0029] Preferably, the second calcination temperature is 600-800°C, and the holding time is ≥3h; the holding time is preferably 3-8h;

[0030] Preferably, the third calcination temperature is 900-1200°C, and the holding time is ≥3h; the holding time is preferably 4-12h;

[0031] Preferably, the cooling out of the furnace can be done by cooling the furnace to room temperature before taking it out of the furnace, or by cooling the furnace to below 450° C. before taking it out of the furnace.

[0032] In a specific embodiment of the present invention, designing a plurality of wax molds according to the casting lumen structure comprises:

[0033] The tube body of the core is divided into an X tube body, a Y tube body, and a Z tube body according to the extension direction;

[0034] A plane formed by the center lines of the X tube body and the Y tube body is used as a first dividing plane, and a plane formed by the center lines of the X tube body and a portion of the Z tube body connected to the X tube body is used as a second dividing plane, and a plurality of the block wax molds are obtained at corresponding positions of the casting wax mold, and are respectively used as a bottom wax mold, a rear wax mold, and a front wax mold;

[0035] Preferably, a first pipeline groove is provided on the bottom wax mold, a second pipeline groove is provided on the rear wax mold, and a third pipeline groove is provided on the front wax mold; the first pipeline groove, the second pipeline groove and the third pipeline groove together form the multi-angle special-shaped lumen.

[0036] In a specific embodiment of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended portion of the tube body is ≤10 mm, the spacing between the suspended portion of the tube body and the cavity wall of the multi-angle special-shaped cavity at the corresponding position is ≤1 mm;

[0037] When the wall thickness of the casting wax mold corresponding to the suspended portion of the tube body is greater than 10 mm, the distance between the suspended portion of the tube body and the cavity wall of the multi-angle special-shaped tube cavity at the corresponding position is ≤ 2 mm;

[0038] Preferably, when the wall thickness of the casting wax mold corresponding to the suspended portion of the tube body is ≤3 mm, the spacing between the suspended portion of the tube body and the cavity wall of the multi-angle special-shaped cavity at the corresponding position is ≤0.5 mm.

[0039] In a specific embodiment of the present invention, the splicing tool comprises a bottom plate having a fixing ring, a sliding plate slidably connected to the bottom plate, and a top pressure plate arranged corresponding to the fixing ring;

[0040] The process of assembling the core and the plurality of wax mold blocks by using a splicing tool comprises the following steps:

[0041] Fixing the rear wax model: installing the rear wax model on the fixing ring of the base plate accordingly;

[0042] Core fixing: placing the X tube body, Y tube body and Z tube body of the core in the second core groove of the rear wax mold;

[0043] Fixing the front wax mold: installing the front wax mold on the rear wax mold, and enclosing part of the third core groove and part of the second core groove to form a tube cavity that sleeves part of the Z tube body;

[0044] Fixing the bottom wax mold: placing the bottom wax mold on the sliding plate, and pushing the sliding plate to splice the bottom wax mold with the rear wax mold and the front wax mold, and making the first pipeline groove, part of the third core groove and part of the second core groove enclose to form a tube cavity sleeved with the X tube body and the Z tube body;

[0045] Fixing of top pressure plate: Install the top pressure plate on the front wax mold and the bottom wax mold, connect it with the fixing ring through the screw rod, and fix it with the nut;

[0046] Melting and fixing: melting at least part of the joints between the bottom wax model, the rear wax model and the front wax model so as to fuse them together.

[0047] In a specific embodiment of the present invention, the splicing tool further includes a plurality of support columns, the support columns are arranged on the outer periphery of the fixing ring, and the support columns are used to support the second pipeline groove of the rear wax model; and / or

[0048] The sliding plate is provided with a positioning block, a supporting block and a side baffle, and the bottom wax mold is arranged on the sliding plate through the positioning block, the supporting block and the side baffle; and / or

[0049] A screw hole is provided in the fixing ring, and a bolt is provided on the top pressure plate. The bolt passes through the center holes of the front and rear membranes and the rear wax mold and is connected to the screw hole with a bolt. The top pressure plate is fixed with a nut on the bolt, and the front and rear membranes and the rear wax mold are fixed.

[0050] In the present invention, the multiple tubes of the core distributed at multiple angles form a multi-dimensional matching relationship with the block wax mold, which not only ensures the precise matching between the block wax mold and the core, but also can use the dimensional accuracy of the core to ensure the dimensional accuracy of the inner cavity of the later casting.

[0051] The preparation method of the present invention adopts that at least part of the tube body of the core is suspended in the multi-angle special-shaped tube cavity, which can avoid the problem that the core cannot be assembled with the multi-angle tube cavity in a certain dimension due to the multiple tube bodies distributed at multiple angles.

[0052] In the present invention, the core is used to splice the bottom wax mold, the rear wax mold and the front wax mold with the help of a splicing tool, which can improve the splicing efficiency and the splicing accuracy.

[0053] The present invention can enhance the stability of the mold shell and the internal core through the fixing effect of the coating area. In the pouring process, when the molten metal is poured into the mold shell, since the coating area and the pouring equipment are fixed, and the core part of the tube body is exposed outside the mold shell and is directly connected to the coating area, the stability of the core when impacted by the molten metal can be enhanced to prevent the core from being offset and affecting the size of the inner cavity of the casting. At the same time, in the centrifugal pouring process, the mold shell can be prevented from being offset on the centrifugal disk due to the centrifugal force during centrifugal pouring, resulting in turbulent flow of the molten metal or incomplete filling. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1-2 Schematic diagram of the overall structure of the casting wax mold from different viewing angles in an embodiment of the present invention;

[0056] Figure 3 It is a structural schematic diagram of a core in an embodiment of the present invention;

[0057] Figure 4 for Figure 1 Schematic diagram of the structure of the midsole wax mold;

[0058] Figure 5-6 for Figure 1 Schematic diagram of the structure of the middle front wax model;

[0059] Figure 7-8 for Figure 1 Schematic diagram of the structure of the middle and rear wax model;

[0060] Fig. 9 It is a structural schematic diagram of a splicing tool in an embodiment of the present invention;

[0061] Figure 10-13 It is a schematic diagram of the coordination state between the splicing tooling and the casting wax model in an embodiment of the present invention.

[0062] Description of reference numerals:

[0063] 1-core; 11-X pipe body; 12-Y pipe body; 13-Z pipe body; 14-Z1 pipe body; 15-Z2 pipe body; 16-Z3 pipe body; 17-Z4 pipe body;

[0064] 2- bottom wax mold, 21- first pipeline groove, 22- first positioning protrusion, 23- second positioning protrusion;

[0065] 3-rear wax model, 31-second pipeline groove, 32-sleeve tube cavity;

[0066] 4-front wax model, 41-third pipeline slot;

[0067] 5-joining tooling, 51-bottom plate, 511-fixing ring, 512-support column, 513-second slide rail, 52-sliding plate, 53-top pressure plate, 54-support block, 55-positioning block, 56-side baffle, 57-screw. DETAILED DESCRIPTION

[0068] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0069] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0070] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0071] For ease of description, spatial relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figure, such as "inside", "outside", "inner side", "outer side", "below", "below", "above", "above", etc. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure is turned over, then the elements described as "below other elements or features" or "below other elements or features" will subsequently be oriented as "above other elements or features" or "above other elements or features". Therefore, the example term "below..." can include both upper and lower orientations. The device can be oriented otherwise (rotated 90 degrees or in other directions) and the spatial relative descriptors used in the text are interpreted accordingly.

[0072] like Figure 1-13 As shown, a method for preparing a casting with a complex lumen proposed in the first aspect of the present invention comprises the following steps:

[0073] Step 100: Core preparation

[0074] The core preparation includes preparing a core 1 according to the shape of the casting tube cavity, and the core 1 includes a plurality of tube bodies distributed at multiple angles.

[0075] In order to facilitate the fixation of the core 1 and the subsequent shell mold, the length of a part of the tube body is greater than the corresponding tube cavity length, so that the tube body can be exposed from the shell mold when the shell mold is prepared.

[0076] Step 200: wax model design

[0077] The casting wax mold is divided into a bottom wax mold 2, a rear wax mold 3 and a front wax mold 4, the bottom wax mold 2 is formed with a first pipeline groove 21, the rear wax mold 3 is formed with a second pipeline groove 31, and the front wax mold 4 is formed with a third pipeline groove 41;

[0078] Specifically, the tube body of the core 1 is divided into an X tube body 11, a Y tube body 12, and a Z tube body 13 according to the extension direction; the X tube body 11, the Y tube body 12, and the Z tube body 13 represent the three-dimensional directions of the coordinate axes X axis, Y axis, and Z axis where the tube body is located, and there is at least one of each X tube body, Y tube body, and Z tube body; a bottom wax mold 2 is separated at a corresponding position of the casting wax mold by taking a plane formed by the center lines of the X tube body 11 and the Y tube body 12 as a dividing plane; and a plane formed by the center lines of the X tube body 11 and a portion of the Z tube body 13 connected to the X tube body 11 as a dividing plane, and the remaining wax mold is separated into a rear wax mold 3 and a front wax mold 4 at a corresponding position of the casting wax mold.

[0079] Therefore, the mutual splicing of the front wax mold 4, the rear wax mold 3 and the bottom wax mold 2 inevitably involves the positioning of the wax mold in the three-dimensional directions of X, Y, and Z, which is conducive to ensuring that the wax mold containing the multi-angle core is accurately positioned in the three-dimensional directions during the splicing process.

[0080] The planes corresponding to the dividing surfaces in the bottom wax mold 2, the rear wax mold 3 and the front wax mold 4 are the splicing surfaces, and the multi-dimensional tube cavity forms grooves on the corresponding splicing surfaces. The diameter of the groove is reset as needed, and the diameter of the groove corresponding to the tube cavity port is made the same as the tube body diameter corresponding to the core 1 so as to form a precise fit with the core 1 during subsequent assembly. The diameter of the groove at other positions is larger than the tube body diameter so that the core 1 is suspended in the tube cavity during subsequent assembly, thereby forming the first pipeline groove 21, the second pipeline groove 31 and the third pipeline groove 41.

[0081] Specifically, when the wall thickness of the wax model corresponding to the suspended portion of the tube body is h≤3mm, the spacing between the suspended portion of the tube body and the groove walls of the first pipeline groove 21, the second pipeline groove 31, and the third pipeline groove 41 is l≤0.5mm. When the wall thickness of the wax model corresponding to the suspended portion of the tube body is 3mm≤h≤10mm, the spacing between the suspended portion of the tube body and the groove walls of the first pipeline groove 21, the second pipeline groove 31, and the third pipeline groove 41 is l≤1mm; when the wall thickness of the wax model corresponding to the suspended portion of the tube body is h>10mm, the spacing between the suspended portion of the tube body and the groove walls of the first pipeline groove 21, the second pipeline groove 31, and the third pipeline groove 41 is l≤2mm.

[0082] By making at least part of the tube body of the core 1 have the same inner diameter as the multi-angle tube cavity at the corresponding position for precise matching, at least part of the tube body and part of the area are suspended in the multi-angle tube cavity, thereby reducing the accuracy requirements for the casting wax mold of the multi-angle tube cavity, reducing the difficulty of assembling the casting wax mold and the core 1, thereby avoiding the problem that the core 1 cannot be assembled with the pipe groove in a certain dimension due to the multi-angle tube cavity.

[0083] In order to facilitate the positioning of the bottom wax mold 2, the rear wax mold 3 and the front wax mold 4, a first positioning protrusion 22 and a second positioning protrusion 23 are provided on the splicing surface of the bottom wax mold 2, a positioning hole adapted to the first positioning protrusion 22 is provided on the rear wax mold 3, and a positioning hole adapted to the second positioning protrusion 23 is provided on the front wax mold 4.

[0084] It should be noted that when designing the partition surface, the tube body connected to the most tube bodies in the core 1 can be the X tube body 11. Then, the Y tube body 12 and the Z tube body 13 are set according to the X tube body 11.

[0085] It should be noted that the X tube body 11 is not necessarily a single tube body, but may also be a plurality of continuous tube bodies. In this embodiment, the X tube body 11 includes an X1 tube body and an X2 tube body connected to each other, and the X1 tube body and the X2 tube body are arranged at an obtuse angle. The Y tube body 12 includes a Y1 tube body connected to the X1 tube body and a Y2 tube body connected to the X2 tube body, and the Z tube body 13 includes a Z1 tube body 14 connected to the X1 tube body and the Y1 tube body, and a Z2 tube body 15 connected to the X2 tube body and the Y2 tube body.

[0086] It should be noted that the X tube body 11, the Y tube body 12, and the Z tube body 13 in the present invention are not necessarily perpendicular to each other, that is, the X tube body 11, the Y tube body 12, and the Z tube body 13 can be perpendicular to each other, or can be arranged at an angle of 0-90 degrees. For example, the Z tube body 13 also includes a Z4 tube body 17 connected to the connection position of the X1 tube body and the X2 tube body, and correspondingly, the bottom wax mold 2 and the rear wax mold 3 are also provided with corresponding limit grooves.

[0087] It should be noted that the Y tube body 12 and the Z tube body 13 in the present invention are not necessarily connected to the X tube body 11. For example, the Z tube body 13 also includes a Z3 tube body 16 connected to the Y tube body 12, and the rear wax mold 3 is also provided with a sleeve cavity 32 for sleeve-connecting the Z3 tube body 16; a partial area of ​​the Z3 tube body 16 has the same inner diameter as the sleeve cavity 32 at the corresponding position for precise matching, and the Z3 tube body 16 and a partial area thereof are suspended in the sleeve cavity 32.

[0088] It should be noted that the length of the tube body in the partial area of ​​the tube body used for precise matching with the multi-angle lumen is ≥8mm.

[0089] It should be noted that the tube body includes a connecting end for connecting to each other and a free end relative to the connecting end. In the present method, a partial area of ​​the tube body for precise matching with the multi-angle lumen is arranged adjacent to the free end; in other embodiments, a partial area of ​​the tube body for precise matching with the multi-angle lumen may also be arranged adjacent to the connecting end.

[0090] It should be noted that, since the X tube body 11, Y tube body 12, and Z tube body 13 of the core are in different planes, when the bottom wax mold 2, the front wax mold 4, the back wax mold 3 and the core 1 are spliced, there will inevitably be assembly interference. For example, after the X tube body 11 and the Y12 tube body are assembled with the bottom wax mold 2, due to the shrinkage and deformation of the wax mold, the front wax mold 4 and the back wax mold 3 cannot be assembled with the X tube body 11 and the Y tube body 12 at the same time as the Z tube body 13 in multiple directions. At this time, the spacing between the suspended part of the tube body and the cavity wall of the multi-angle tube cavity can be used as a space for adjusting interference.

[0091] Step 300: Preparation of basic wax model

[0092] The wax mold is prepared according to the designed bottom wax mold 2, rear wax mold 3 and front wax mold 4, wherein the bottom wax mold 2, rear wax mold 3 and front wax mold 4 can be prepared by 3D printing; the outline of the basic wax mold prepared by 3D printing meets the design requirements, and the interior is a hollow structure to reduce the overall weight of the 3D printed wax mold;

[0093] The bottom wax mold 2, the rear wax mold 3 and the front wax mold 4 are cleaned and partially repaired on the surface.

[0094] Step 400: Preparation of overall wax model

[0095] The core 1 is spliced ​​with the bottom wax mold 2, the rear wax mold 3, and the front wax mold 4 by using a splicing tool 5, and the core 1 is placed in a multi-angle tube cavity formed by the first pipeline groove 21, the second pipeline groove 31, and the third pipeline groove 41 to obtain an integral wax mold with a multi-angle tube cavity; and at least part of the area of ​​the tube body of the core 1 is the same as the inner diameter of the multi-angle tube cavity at the corresponding position for precise matching, and the remaining area of ​​the core 1 is suspended in the multi-angle tube cavity.

[0096] Specifically, the splicing tool 5 includes a bottom plate 51 having a fixing ring 511 , a sliding plate 52 slidably connected to the bottom plate 51 , and a top pressure plate 53 arranged corresponding to the fixing ring 511 .

[0097] Using the splicing tool 5 to splice the core 1 with the bottom wax mold 2, the rear wax mold 3 and the front wax mold 4 includes the following steps in sequence:

[0098] Fixing the rear wax mold 3: The rear wax mold 3 is installed on the fixing ring 511 of the base plate 51; wherein the shape of the fixing ring 511 is adapted to the shape of the center hole of the rear wax mold 3, so that the rear wax mold 3 can be placed on the base plate 51 with the splicing surface facing upward.

[0099] At this time, the X and Y directions of the rear wax mold 3 are fixed because they are in contact with the fixing ring 511, and the Z direction is further limited by the support column 512 to ensure that the rear wax mold 3 is accurately positioned in the three directions of XYZ.

[0100] Fix the core 1: place the X tube body 11, Y tube body 12 and Z tube body 13 of the core 1 in the second pipe groove 31 of the rear wax mold 3, the Z3 tube body 16 is sleeved in the sleeve tube cavity 32 of the rear wax mold 3, and the Z4 tube body 17 is located in the limiting groove of the rear wax mold 3, so that the core 1 is positioned and connected to the rear wax mold 3 in the three directions of XYZ.

[0101] Fix the front wax model 4: install the front wax model 4 on the rear wax model 3, and part of the third pipe groove 41 and part of the second pipe groove 31 enclose a tube cavity that sleeves part of the Z tube body 13; limit the Z direction of the spliced ​​rear wax model 3 and the front wax model 4 through the support column 512, so that the spliced ​​rear wax model 3 and the front wax model 4 are accurately positioned in the three directions of XYZ.

[0102] The bottom wax mold 2 is fixed: the bottom wax mold 2 is placed on the sliding plate 52, and the sliding plate 52 is pushed to splice the bottom wax mold 2 with the rear wax mold 3 and the front wax mold 4, and the first pipeline groove 21 and part of the third pipeline groove 41 and part of the second pipeline groove 31 are enclosed to form a tube cavity for sleeve-connecting the X tube body 11 and the Z tube body 13, and the Z4 tube body 17 is located in the limiting groove of the bottom wax mold 2. Specifically, the bottom plate 51 is provided with a second slide rail 513 and a slider slidably connected to the second slide rail 513, and the sliding plate 52 is connected to the slider to slide relatively on the bottom plate 51; the bottom wax mold 2 is fixed at a preset angle by a positioning block 55, a support block 54 and a side baffle 56 provided on the sliding plate 52. Since the bottom wax mold 2 is fixed at a preset angle after positioning, it can ensure accurate positioning with the rear wax mold 3 and the front wax mold 4 during the splicing process, and it is easier to assemble with the rear wax mold 3 and the front wax mold 4 through the sliding device on the sliding plate 52.

[0103] During splicing, the first positioning protrusion 22 and the second positioning protrusion 23 on the bottom wax mold 2 are respectively adapted and positioned with the positioning holes at the corresponding positions of the front wax mold 4 and the rear wax mold 3 to further ensure the assembly accuracy.

[0104] Fixing of the top pressure plate 53: After the bottom wax mold 2 and the front wax mold 4 and the rear wax mold 3 are spliced ​​into a whole, the top pressure plate 53 is installed on the front wax mold 4 and the bottom wax mold 2, and connected to the fixing ring 511 through the screw 57. Specifically, the fixing ring 511 is provided with a threaded hole, the top pressure plate 53 is provided with a through hole, and a screw 57 is inserted in the through hole of the top pressure plate 53, and the screw 57 passes through the center holes of the rear wax mold 3 and the front wax mold 4 in turn to connect with the threaded hole on the fixing ring 511, and the top pressure plate 53 and the fixing ring 511 are locked above the through hole of the top pressure plate 53 by using a nut, so as to realize the close splicing of the bottom wax mold 2 and the front wax mold 4 and the rear wax mold 3. At this time, further through the joint action of the top pressure plate 53 and the support column 512, the accurate positioning of the spliced ​​bottom wax mold 2 and the front wax mold 4 and the rear wax mold 3 in the three directions of XYZ is realized.

[0105] Envelope fixing: An elastic envelope is sleeved on the outside of the tubular splicing structure formed by the first pipeline groove 21, the second pipeline groove 31 and / or the third pipeline groove 41; the envelope is made of elastic material and can tightly fix at least two wax mold blocks and the core 1.

[0106] Melting and fixing: melt at least part of the joints between the bottom wax mold 2, the rear wax mold 3, and the front wax mold 4 to fuse them together. Specifically, the joints can be melted by an electric soldering iron to achieve melting and fusion connection of the wax mold, the rear wax mold 3, and the front wax mold 4.

[0107] It should be noted that the splicing tool 5 also includes a plurality of support columns 512, which are arranged on the outer periphery of the fixing ring 511, and the support columns 512 are used to support the second pipe groove 31 of the rear wax mold 3. In this embodiment, the number of the support columns 512 is 4, and the 4 support columns 512 are respectively arranged corresponding to the pipe ends of the X1 pipe body, the X2 pipe body, the Y1 pipe body, and the Y2 pipe body.

[0108] Step 500: Shell preparation

[0109] Surface shell preparation

[0110] The surface of the casting wax mold is coated with a surface layer slurry, and then the excess surface layer slurry is removed; then the surface layer is sanded and dried to form a surface shell.

[0111] Back shell preparation includes:

[0112] Apply the back layer slurry on the surface of the surface shell, and remove the excess back layer slurry; then, sprinkle sand on the back layer, and after drying, form the first back layer shell;

[0113] The steps of coating the back layer slurry and sprinkling the back layer with sand in the preparation of the back layer shell are repeated many times to form a multi-layer back layer shell.

[0114] It is worth mentioning that during the coating of the surface layer slurry and the back layer slurry, the tube body that passes through the multi-angle special-shaped tube cavity and is exposed outside the casting wax mold is protected, and this part of the tube body of the core 1 is always kept exposed outside the casting shell.

[0115] It should be noted that before applying the surface layer slurry to prepare the surface layer shell, the surface of the wax mold can be cleaned to remove surface stains.

[0116] In a specific embodiment of the present invention, the shell dewaxing comprises:

[0117] After heating to the dewaxing temperature, keep the temperature until the wax liquid flows out from the dewaxing port, and then cool the shell to room temperature along with the furnace;

[0118] Preferably, the dewaxing temperature is 100-250°C and the holding time is 3-8h;

[0119] Preferably, the wax liquid flows out from the wax outlet in the middle or side of the bottom area of ​​the shell.

[0120] In a specific embodiment of the present invention, the segmented shell roasting comprises:

[0121] After heating to the first, second and third roasting temperatures, keep them warm respectively, and then cool them down and take them out of the furnace;

[0122] Preferably, the first calcination temperature is 500-600°C, and the holding time is ≥3h; the holding time is preferably 3-6h;

[0123] Preferably, the second calcination temperature is 600-800°C, and the holding time is ≥3h; the holding time is preferably 3-8h;

[0124] Preferably, the third calcination temperature is 900-1200°C, and the holding time is ≥3h; the holding time is preferably 4-12h;

[0125] Preferably, the cooling out of the furnace can be done by cooling the furnace to room temperature before taking it out of the furnace, or by cooling the furnace to below 450° C. before taking it out of the furnace.

[0126] In certain embodiments of the present invention, the dewaxing temperature is 100-250° C., and the holding time is 3-8 hours.

[0127] Exemplarily, the dewaxing temperature is one of 100°C, 110°C, 117°C, 150°C, 250°C, etc., or any value that satisfies the above range. The holding time is one of 3, 4, 5, 6, 7, 7.3, 7.5, 8h, etc., or any value that satisfies the above range. Preferably, after the shell is dewaxed but before being fired, the tube body of the core that passes through the inner cavity of the shell and is exposed outside the shell of the casting is coated with the same material as the shell, and the coated area is connected to part of the shell.

[0128] By coating the tube body of the core that passes through the inner cavity of the shell and is exposed outside the shell of the casting after dewaxing of the shell and before firing, it is possible to avoid the situation where the dewaxing temperature is low and the coating area can only be partially dried but not ceramicized when heated at this temperature. The heating and cooling process of dewaxing involves thermal expansion and contraction of the coating area, which makes it impossible for the coating area to be completely connected with the shell and the tube body of the core that is exposed outside the shell.

[0129] After the shell is baked, the inner cavity of the shell and the surface of the core 1 are checked with an endoscope to prevent cracks in the inner cavity of the shell and the surface of the core 1.

[0130] The inside of the casting shell is cleaned by blowing with an air gun.

[0131] Step 600 and melting and pouring

[0132] The casting is poured using the casting shell to obtain a casting with a core 1; before the molten metal is poured, the shell is preheated, and to ensure the stability of the shell, the preheating temperature is between 300-500°C.

[0133] Preferably, the mold shell covering area can be used as a fixing area for the mold shell and the pouring equipment.

[0134] The fixing effect of the coating area can enhance the stability of the shell and the internal core. For the pouring process, when the molten metal is poured into the shell, the coating area and the pouring equipment are fixed, and the core part of the tube body is exposed outside the shell and directly connected to the coating area, which can enhance the stability of the core when it is impacted by the molten metal and prevent it from shifting and affecting the inner cavity size of the casting. At the same time, for the centrifugal casting method, it can prevent the shell from shifting on the centrifugal disk due to the centrifugal force during centrifugal casting, which leads to turbulent filling of the molten metal or incomplete filling.

[0135] Preferably, the casting is poured by gravity or centrifugation.

[0136] The core 1 in the casting is removed to obtain a casting with a multi-angle tube cavity. Specifically, the core 1 in the casting is removed by vibration or corrosion. The core 1 remaining inside the casting is removed by grinding.

[0137] Furthermore, after the casting is poured, the core 1 inside the casting is removed.

[0138] The second aspect of the present invention further provides a shell mold, which is mainly prepared by the shell preparation method. Since the shell mold in this embodiment and the preparation method are in the same technical concept, the shell mold in this embodiment also has the beneficial effects of the preparation method.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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.

Claims

1. A method for preparing a casting with a complex lumen, characterized in that: The following steps are involved: Prepare a core according to the shape of the casting tube cavity, wherein the core includes a plurality of tube bodies distributed at multiple angles; Design multiple wax molds according to the casting lumen structure; The core is assembled with the plurality of the divided wax models by using a splicing tool to form an integral wax model with a multi-angle special-shaped lumen, and the core is placed in the multi-angle special-shaped lumen; wherein at least a portion of the tubular body of the core has the same inner diameter as the multi-angle special-shaped lumen at the corresponding position for precise matching, and the remaining portion is suspended in the multi-angle special-shaped lumen; The surface of the integral wax mold is coated with slurry, dried, dewaxed and fired to form a casting shell; The casting shell is melted and poured, and then the internal core is removed to obtain the casting.

2. The method for preparing a casting with a complex lumen according to claim 1, characterized in that: Melting and pouring the casting wax pattern to obtain the casting includes: Using the casting shell to cast the casting to obtain a casting with a core; The core inside the casting is removed to obtain a casting with a multi-angle lumen.

3. The method for preparing a casting with a complex lumen according to claim 2, characterized in that: Vibration and grinding to remove cores from castings; and / or The mold shell is preheated before pouring, and the preheating temperature is between 300-500℃.

4. The method for preparing a casting with a complex lumen according to claim 2, characterized in that: The surface of the integral wax mold is coated with slurry, and after drying, a shell is formed, which includes: Preparation of surface shell: coating the surface of the integral wax mold with surface slurry, and then removing excess surface slurry; The integral wax mold is subjected to surface sanding, and after drying, a surface shell is formed; Preparation of back layer shell: coating the surface of the surface shell with back layer slurry and removing excess back layer slurry; then performing back layer sanding and drying to form a back layer shell; The back layer shell preparation steps are repeated multiple times to form a multi-layer back layer shell.

5. The method for preparing a casting with a complex lumen according to claim 1, characterized in that: The shell dewaxing process comprises: After heating to the dewaxing temperature, keep the temperature until the wax liquid flows out from the dewaxing port, and then cool the shell to room temperature along with the furnace; Preferably, the dewaxing temperature is 100-250° C., and the holding time is 3-8 hours; preferably, the wax liquid flows out from the wax outlet in the middle or side of the bottom area of ​​the shell; and / or The shell roasting comprises: After heating to the first, second and third roasting temperatures, keep them warm respectively, and then cool them down and take them out of the furnace; Preferably, the first calcination temperature is 500-600°C, and the holding time is ≥3h; the holding time is preferably 3-6h; Preferably, the second calcination temperature is 600-800°C, and the holding time is ≥3h; the holding time is preferably 3-8h; Preferably, the third calcination temperature is 900-1200°C, and the holding time is ≥3h; the holding time is preferably 4-12h; Preferably, the cooling out of the furnace can be done by cooling the furnace to room temperature before taking it out of the furnace, or by cooling the furnace to below 450° C. before taking it out of the furnace.

6. The method for preparing a casting with a complex lumen according to claim 1, characterized in that: Design multiple wax models based on the casting lumen structure including: The tube body of the core is divided into an X tube body, a Y tube body, and a Z tube body according to the extension direction; A plane formed by the center lines of the X tube body and the Y tube body is used as a first dividing plane, and a plane formed by the center lines of the X tube body and a portion of the Z tube body connected to the X tube body is used as a second dividing plane, and a plurality of the block wax molds are obtained at corresponding positions of the casting wax mold, and are respectively used as a bottom wax mold, a rear wax mold, and a front wax mold; Preferably, a first pipeline groove is provided on the bottom wax mold, a second pipeline groove is provided on the rear wax mold, and a third pipeline groove is provided on the front wax mold; the first pipeline groove, the second pipeline groove and the third pipeline groove together form the multi-angle special-shaped lumen.

7. The method for preparing a casting with a complex lumen according to claim 1, characterized in that: When the wall thickness of the casting wax mold corresponding to the suspended portion of the tube body is ≤10 mm, the distance between the suspended portion of the tube body and the cavity wall of the multi-angle special-shaped tube cavity at the corresponding position is ≤1 mm; When the wall thickness of the casting wax mold corresponding to the suspended portion of the tube body is greater than 10 mm, the distance between the suspended portion of the tube body and the cavity wall of the multi-angle special-shaped tube cavity at the corresponding position is ≤ 2 mm; Preferably, when the wall thickness of the casting wax mold corresponding to the suspended portion of the tube body is ≤3 mm, the spacing between the suspended portion of the tube body and the cavity wall of the multi-angle special-shaped cavity at the corresponding position is ≤0.5 mm.

8. The method for preparing a casting with a complex lumen according to claim 6, characterized in that: The splicing tooling comprises a bottom plate with a fixing ring, a sliding plate slidably connected to the bottom plate, and a top pressure plate arranged corresponding to the fixing ring; The process of assembling the core and the plurality of wax mold blocks by using a splicing tool comprises the following steps: Fixing the rear wax model: installing the rear wax model on the fixing ring of the base plate accordingly; Core fixing: placing the X tube body, Y tube body and Z tube body of the core in the second core groove of the rear wax mold; Fixing the front wax mold: installing the front wax mold on the rear wax mold, and enclosing part of the third core groove and part of the second core groove to form a tube cavity that sleeves part of the Z tube body; Fixing the bottom wax mold: placing the bottom wax mold on the sliding plate, and pushing the sliding plate to splice the bottom wax mold with the rear wax mold and the front wax mold, and making the first pipeline groove, part of the third core groove and part of the second core groove enclose to form a tube cavity sleeved with the X tube body and the Z tube body; Fixing of top pressure plate: Install the top pressure plate on the front wax mold and the bottom wax mold, connect it with the fixing ring through the screw rod, and fix it with the nut; Melting and fixing: melting at least part of the joints between the bottom wax model, the rear wax model and the front wax model so as to fuse them together.

9. The method for preparing a casting with a complex lumen according to claim 8, characterized in that: The splicing tool further includes a plurality of support columns, which are arranged on the outer periphery of the fixing ring and are used to support the second pipeline groove of the rear wax model; and / or The sliding plate is provided with a positioning block, a supporting block and a side baffle, and the bottom wax mold is arranged on the sliding plate through the positioning block, the supporting block and the side baffle; and / or A screw hole is provided in the fixing ring, and a bolt is provided on the top pressure plate. The bolt passes through the center holes of the front and rear membranes and the rear wax mold and is connected to the screw hole with a bolt. The top pressure plate is fixed with a nut on the bolt, and the front and rear membranes and the rear wax mold are fixed.

10. A casting mold with a complex lumen, characterized in that: The casting is prepared by the casting preparation method described in any one of claims 1 to 9.

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