CN114425598A - Preparation method of titanium and titanium alloy casting containing special-shaped gap holes - Google Patents
Preparation method of titanium and titanium alloy casting containing special-shaped gap holes Download PDFInfo
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- CN114425598A CN114425598A CN202111678469.7A CN202111678469A CN114425598A CN 114425598 A CN114425598 A CN 114425598A CN 202111678469 A CN202111678469 A CN 202111678469A CN 114425598 A CN114425598 A CN 114425598A
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- 238000005266 casting Methods 0.000 title claims abstract description 97
- 229910001069 Ti alloy Inorganic materials 0.000 title claims abstract description 44
- 239000010936 titanium Substances 0.000 title claims abstract description 39
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 title claims abstract description 38
- 229910052719 titanium Inorganic materials 0.000 title claims abstract description 38
- 238000002360 preparation method Methods 0.000 title claims abstract description 30
- 210000001503 joint Anatomy 0.000 claims abstract description 20
- 238000000034 method Methods 0.000 claims abstract description 17
- 238000003466 welding Methods 0.000 claims abstract description 16
- 230000007547 defect Effects 0.000 claims abstract description 11
- 238000005520 cutting process Methods 0.000 claims abstract description 10
- 238000005498 polishing Methods 0.000 claims abstract description 10
- 238000005554 pickling Methods 0.000 claims abstract description 9
- 238000003723 Smelting Methods 0.000 claims abstract description 6
- 239000002002 slurry Substances 0.000 claims description 36
- 239000010410 layer Substances 0.000 claims description 34
- 239000002344 surface layer Substances 0.000 claims description 25
- 230000003014 reinforcing effect Effects 0.000 claims description 17
- 239000004576 sand Substances 0.000 claims description 16
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 238000004140 cleaning Methods 0.000 claims description 9
- 238000011049 filling Methods 0.000 claims description 9
- 238000005507 spraying Methods 0.000 claims description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 8
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 6
- 230000001680 brushing effect Effects 0.000 claims description 6
- 239000011248 coating agent Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 238000001514 detection method Methods 0.000 claims description 4
- 238000000227 grinding Methods 0.000 claims description 4
- 238000007581 slurry coating method Methods 0.000 claims description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 3
- 239000004115 Sodium Silicate Substances 0.000 claims description 3
- 238000009750 centrifugal casting Methods 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 3
- 230000005484 gravity Effects 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 229910017604 nitric acid Inorganic materials 0.000 claims description 3
- 238000002791 soaking Methods 0.000 claims description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 3
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 3
- 239000000945 filler Substances 0.000 claims 1
- 238000005058 metal casting Methods 0.000 abstract description 2
- 239000011162 core material Substances 0.000 description 18
- 229910052751 metal Inorganic materials 0.000 description 13
- 239000002184 metal Substances 0.000 description 13
- 230000008569 process Effects 0.000 description 6
- 238000005495 investment casting Methods 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005429 filling process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 1
- 239000003870 refractory metal Substances 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 150000003608 titanium Chemical class 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/04—Use of lost patterns
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C7/00—Patterns; Manufacture thereof so far as not provided for in other classes
- B22C7/02—Lost patterns
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D13/00—Centrifugal casting; Casting by using centrifugal force
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
- B22D27/15—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting by using vacuum
Abstract
The invention relates to the field of metal casting, and particularly discloses a method for preparing titanium and titanium alloy castings containing special-shaped clearance holes, wherein the titanium and titanium alloy castings are provided with the special-shaped clearance holes, and the method sequentially comprises the following steps: preparing a basic wax mould, preparing an integral wax mould, preparing a shell, smelting and pouring, cutting and polishing an auxiliary structure, welding and locally pickling; the preparation of the basic wax mould comprises the following steps: according to different structures of the special-shaped clearance holes of the titanium and titanium alloy castings, the special-shaped clearance holes are divided into an A-area integral wax pattern, a B-area integral wax pattern and a C-area integral wax pattern, wherein the A-area integral wax pattern comprises: the wax pattern in the area A, the upper single sheet and the lower single sheet are positioned by the concave butt joint groove and the convex butt joint groove to form an integral wax pattern. The method can be used for preparing titanium and titanium alloy castings with special-shaped clearance holes, and can effectively solve the problems that thin-wall precise titanium and titanium alloy castings with complex inner cavities are difficult to form, low in dimensional precision and difficult to treat metallurgical defects.
Description
Technical Field
The invention relates to the field of metal casting, and particularly discloses a preparation method of a titanium and titanium alloy casting containing special-shaped gap holes.
Background
Titanium and titanium alloy castings are widely applied to the fields of aviation, aerospace, ships and weapons, high-precision titanium and titanium alloy castings are generally mainly prepared by adopting an investment casting precision casting technology, and an inner cavity of the casting is mainly formed by using a prefabricated ceramic core or a metal core and is removed after the casting is cast. For the ceramic core, when the inner cavity is long or irregular and has a small inner diameter, the problems of difficult core removal, low finish degree of the inner wall of the casting and the like exist. For metal cores, refractory metals are often used to make cores due to the chemical activity of titanium and titanium alloys, but the problems of no deformability of the cores, difficulty in cleaning, high cost, limited application, etc. exist. The Chinese patent application with the publication number CN 101745602A discloses a method for preparing a fusible metal core for titanium alloy investment casting, wherein the metal core material selects solid aluminum, magnesium, zinc and alloy thereof, and rare earth oxide is sprayed on the surface of the metal core. When the metal core in the patent is adopted to produce the titanium alloy casting with the slender inner cavity, the surface spraying substance of the metal core is easy to form a pollution layer on the inner surface of the casting, and the removing process of the metal core can increase the production cost. The Chinese patent application with publication number CN 102806311A discloses a complex pipeline forming process for a titanium alloy investment casting, wherein the metal core is made of pure titanium or a material with the same brand as the casting, the shell roasting temperature is 980-1020 ℃, the heat preservation time is 4-4.5 hours, and in order to reduce the oxidation problem of the metal core caused by long-time high-temperature roasting, graphite powder with high-temperature vacuum degassing is filled in the metal core. The titanium alloy casting with a slender inner cavity produced by the process has the advantages that the metal core is roasted at a high temperature above the beta phase transition temperature to coarsen the structure, so that the overall performance of the casting is reduced, and meanwhile, the graphite powder filled in the metal core needs to be specially treated before use, so that the production cost is increased, and the pollution to the inner cavity of the casting is caused. With the continuous development of the aerospace field in China, the shape and the structure of the titanium alloy casting are more and more complex, and higher requirements are provided for the quality and the performance of titanium and the titanium alloy casting with a complex inner cavity.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, the above-mentioned technical problems in the related art. Therefore, the invention provides a method for preparing titanium and titanium alloy castings containing special-shaped clearance holes, and the method can be used for preparing the titanium and titanium alloy castings containing the special-shaped clearance holes and can effectively solve the problem that thin-wall precise titanium and titanium alloy castings with complex inner cavities are difficult to form.
In order to achieve the above object, a first aspect of the present invention provides a method for preparing a titanium and titanium alloy casting containing a profiled clearance hole, the titanium and titanium alloy casting having a profiled clearance hole, comprising the following steps in order: preparing a basic wax mould, preparing an integral wax mould, preparing a shell, smelting and pouring, cutting and polishing an auxiliary structure, welding and locally pickling;
wherein, the preparation of the basic wax mould comprises the following steps: according to different structures of the special-shaped clearance holes of the titanium and titanium alloy castings, the special-shaped clearance holes are divided into an A-area integral wax pattern, a B-area integral wax pattern and a C-area integral wax pattern, wherein the A-area integral wax pattern comprises: the part A area wax pattern, the upper single sheet and the lower single sheet are provided with concave butt joint grooves at the upper edge and the lower edge; the upper single sheet and the lower single sheet are provided with convex butt joint grooves matched with the concave butt joint grooves, and the B-area integral wax pattern comprises a part of B-area wax pattern and a conformal single sheet;
designing a basic wax mold preparation mold according to the structures and the sizes of the casting and the special-shaped clearance hole, and then carrying out basic wax mold preparation to form a basic wax mold provided with a part of A-area wax mold, a part of B-area wax mold and a C-area integral wax mold;
the preparation of the integral wax mould comprises the following steps: and respectively combining the upper single sheet and the lower single sheet to the upper edge and the lower edge of the partial A-area wax pattern, and performing position positioning by utilizing the concave butt joint groove and the convex butt joint groove to form an integral wax pattern.
In addition, the preparation method of the titanium and titanium alloy casting containing the special-shaped clearance hole can also have the following additional technical characteristics:
according to some embodiments of the invention, the wax pattern of the part B region is provided with a window, and the window is provided with at least one lug;
the profile of the conformal single sheet is matched with the profile of the window;
the conformal single sheet is provided with a lug plate matched with the concave lug plate.
According to some embodiments of the invention, the a-zone integral wax pattern comprises: a support structure and a reinforcing structure;
the preparation of the basic wax mould comprises the following steps: cleaning the basic wax pattern and removing parting lines on the surfaces of the partial A-area wax pattern, the partial B-area wax pattern and the partial C-area integral wax pattern;
the preparation of the integral wax mould also comprises the following steps: mounting a support structure between the upper and lower monoliths; respectively installing reinforcing structures on the upper single chip and the lower single chip, and respectively connecting the upper single chip and the lower single chip with the basic wax pattern;
and combining the conformal single sheets to a pouring channel of the integral wax mould module, and adding pouring channel support to the lug positions.
According to some embodiments of the invention, the integral wax pattern preparation further comprises the steps of: and performing surface finishing and polishing on the contact positions of the basic wax pattern, the upper single sheet, the lower single sheet, the supporting structure and the reinforcing structure, and cleaning the whole wax pattern.
According to some embodiments of the invention, the shell preparation comprises the steps of:
coating surface layer slurry on the surface of the integral wax mould, and then removing the redundant surface layer slurry;
brushing or pouring the integral wax pattern in the area A, the integral wax pattern in the area B and the integral wax pattern in the area C, and increasing the thickness of the slurry of the surface layer in the area of the special-shaped gap hole;
carrying out surface layer sand spraying on the integral wax mold to form a surface layer shell;
preparing a back layer shell: coating back layer slurry on the surface of the surface layer shell, and removing the redundant back layer slurry;
carrying out secondary brushing or pouring on the integral wax pattern in the area A, the integral wax pattern in the area B and the integral wax pattern in the area C, and increasing the thickness of the back layer slurry;
carrying out back layer sand spraying on the integral surface layer shell to form a first back layer shell;
filling the gap of the integral wax pattern in the area C through the window;
repeating the first and third steps of the back-layer-type-shell preparation a plurality of times to form a multi-layered back-layer-type shell;
and roasting the multilayer back layer shell mold to prepare a casting shell mold.
According to some embodiments of the invention, the step of removing excess backing layer paste comprises: and accelerating the slurry dripping by adopting a mode of rotating and inclining the whole wax mold in the B area, then performing secondary slurry coating on the whole wax mold in the B area, and rotating and inclining the whole wax mold again to accelerate the slurry dripping.
According to some embodiments of the invention, the step of filling the gap of the C-zone integral wax pattern comprises:
and filling the gap of the integral wax pattern in the area C by using a viscous slurry sand mixture formed by mixing back layer slurry and back layer sand.
According to some embodiments of the invention, the smelting and pouring comprises the steps of:
detecting the quality of the special-shaped gap of the casting shell through a window;
casting pouring is carried out by utilizing a casting shell to obtain a basic casting and a random single casting;
centrifugal casting or gravity casting is carried out by utilizing the casting shell under vacuum.
According to some embodiments of the invention, the auxiliary structure cutting grinding comprises the steps of: cutting a free-form single sheet from a gating system, cutting a supporting structure and a reinforcing structure of a basic casting, and polishing the cut edge;
the welding comprises the following steps: performing nondestructive detection on the casting positions corresponding to the integral wax pattern in the area B and the integral wax pattern in the area C, and plugging the window when no internal defect exists; when the internal defect exists, the internal defect is repaired through the window;
designing a mold according to the sizes of the gaps of the window and the integral wax mold in the B area, and preparing a supporting block;
the material of the supporting block comprises: 40-50% of liquid sodium silicate and the balance of graphite powder. Drying the prepared supporting block at the temperature of 150-; placing the supporting block in a gap of the window, then placing a random type single sheet on the surface, and plugging the window by the random type single sheet in a welding mode;
and carrying out surface grinding on the outer surface of the welding area.
According to some embodiments of the invention, the partial pickling comprises the steps of:
soaking the supporting block, and discharging graphite powder through the integral wax mold in the area A or the integral wax mold in the area C after the supporting block is crushed;
and (3) locally cleaning the abnormal gaps of the integral wax mold in the area A, the integral wax mold in the area B and the integral wax mold in the area C by adopting a hydrofluoric acid and nitric acid mixed solution, and pickling and removing the integral wax mold in the area B and the integral wax mold in the area C with the wall thickness increased by 0.3-2 mm compared with the actual wall thickness to obtain a final casting.
Compared with the prior art, the invention has the following beneficial effects:
according to different structures of the special-shaped clearance holes of the titanium and titanium alloy castings, casting wax molds are respectively formed to form the special-shaped clearance holes of the castings, so that the problems that the special-shaped clearance holes of the thin-wall titanium and titanium alloy castings are difficult to form, easy to deform during welding and the like can be effectively solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a partial structural sectional view of an integral wax pattern of a titanium and titanium alloy casting containing a profiled clearance hole according to an embodiment of the present invention;
FIG. 2 is a partial sectional view of a basic wax pattern of a titanium and titanium alloy casting containing a special-shaped clearance hole according to an embodiment of the invention;
FIG. 3 is a rear view of a basic wax pattern structure of a titanium and titanium alloy casting containing a special-shaped clearance hole according to an embodiment of the present invention;
FIG. 4 is a top view of a cross-sectional structure of a base wax pattern of a titanium and titanium alloy casting containing a shaped clearance hole according to an embodiment of the present invention;
FIG. 5 is a perspective view of a conformal monolithic plate according to an embodiment of the present invention;
FIG. 6 is a perspective view of a single piece of the present invention;
FIG. 7 is a perspective view of a lower single piece in accordance with an embodiment of the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only, and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprising," "including," and "having" are inclusive and therefore specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof.
In the description of the present invention, unless otherwise explicitly specified or limited, the terms "disposed" and "connected" are to be construed broadly, e.g., as meaning a fixed connection, a detachable connection, or an integral connection; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first", "second", may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
For convenience of description, spatially relative terms, such as "bottom," "front," "upper," "oblique," "lower," "top," "inner," "horizontal," "outer," and the like, may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. This spatially relative relationship is intended to encompass different orientations of the mechanism in use or operation in addition to the orientation depicted in the figures. For example, if the mechanism in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" or "over" the other elements or features. Thus, the example term "below … …" can include both an orientation of above and below.
Referring to fig. 1-7, the method for preparing titanium and titanium alloy castings containing special-shaped clearance holes according to the embodiment of the present invention includes the following steps:
step 100, preparing a basic wax mold
Dividing the special-shaped gap hole structure of the casting into three parts, namely an integral wax mold 1 in an area A, an integral wax mold 2 in an area B and an integral wax mold 3 in an area C, and respectively preparing the wax molds;
wherein, whole wax matrix 1 in A district includes: the part A area wax pattern 11, an upper single sheet 12, a lower single sheet 13, a supporting structure 14 and a reinforcing structure 15; the upper edge and the lower edge of the wax mould 11 of the area A are provided with concave butt joint grooves 16, and the number of the concave butt joint grooves is not less than 1; the upper single sheet 12 and the lower single sheet 13 are provided with convex butt joint grooves 17 matched with the concave butt joint grooves 16 in shape and size, and the number of the convex butt joint grooves is the same as that of the concave butt joint grooves 16;
the B-area integral wax pattern 2 comprises: a part B area wax pattern 21 and a conformal single sheet 23; the wax pattern 21 of the part B area comprises a window 22; the number of window 22 is no less than 1, and the shape is preferably rectangle, and length is between 0.4 ~ 0.8 times of the whole wax matrix 2 gap length in B district, and maximum dimension is no more than 50mm, and the width is between 0.4 ~ 0.8 times of the whole wax matrix 2 gap width size in B district. When the length of the gap of the whole wax mould 2 in the area B is more than 50mm, more than 1 window 22 can be arranged optionally. The viewing window 22 is preferably located in the middle of the B-region integral wax pattern 2. The window 22 has at least one tab 24, which is selected from the group consisting of semi-circular, rectangular, square, saw-toothed, and preferably semi-circular.
The contour of the conformal single sheet 23 is matched with the contour of the window 22, and the range of the contour size smaller than the window 22 is between 0.5mm and 2.5 mm; during later welding, the outline dimensions of the conformal single sheets 23 are more easily matched with the window 22, and the welding precision is improved under the auxiliary action of the supporting block;
the conformal single sheet is provided with lug pieces 25 which are matched with the concave lug pieces 24, and the number of the lug pieces 25 is the same as that of the concave lug pieces 24; the lug plates 25 are connected with the concave lug plates 24 in a crossed manner, so that the overall strength of the welded area is improved;
the wall thickness of the integral wax mold 2 in the area B and the integral wax mold 3 in the area C is increased by 0.3-2 mm compared with the actual wall thickness; the increased wall thickness is the reserved wall thickness of the casting, so that the problem that the wall thickness of the position of the casting is reduced due to pickling in the later period and the size requirement cannot be met is avoided;
designing a basic wax mold preparation mold according to the structure and the size of the special-shaped gap hole of the casting, and then preparing the basic wax mold to form a basic wax mold with a part of the A-area wax mold 11, a part of the B-area wax mold 21 and a C-area integral wax mold 3;
cleaning the basic wax pattern and removing parting lines on the surfaces of the part A area wax pattern 11, the part B area wax pattern 21 and the part C area integral wax pattern 3;
and removing the parting line of the surfaces of the partial B-area wax pattern 21 and the C-area integral wax pattern 3 through the window 22 on the partial B-area wax pattern 21 by using a blade or a scraper. Due to the existence of the window 22, the surface of the wax mould on the inner wall of the special-shaped slit hole of the casting can be further trimmed, the surface smoothness of the wax mould on the inner wall is improved, and the surface quality of the casting is further improved.
Step 200, preparing an integral wax mold
Respectively combining an upper single sheet 12 and a lower single sheet 13 to the upper edge and the lower edge of the wax pattern 11 in the area A by adopting a local heating or partial melting method, and performing position positioning by utilizing the matching of a concave butt joint groove 16 and a convex butt joint groove 17 to form an integral wax pattern;
and a support structure 14 is arranged between the upper single sheet 12 and the lower single sheet 13, and the number of the support structures 14 is not less than 1. The supporting structure 14 can simultaneously support the upper single sheet 12 and the lower single sheet 13, so that the influence on the size precision of the special-shaped gap hole caused by the deformation of the upper single sheet 12 and the lower single sheet 13 in the casting molding process is avoided. Reinforcing structures 15 are respectively installed on the upper single sheet 12 and the lower single sheet 13 for respectively connecting the upper single sheet 12 and the lower single sheet 13 with the basic wax pattern. The upper single sheet 12, the lower single sheet 13 and the basic wax pattern can form a structural whole by utilizing the additionally added reinforcing structure 15, so that the structural stability of the upper single sheet 12 and the lower single sheet 13 is favorably improved, and the dimensional accuracy of the casting in the area is further improved.
The outline of the reinforcing structure 15 is matched with the basic wax pattern, the upper single sheet 12 and the lower single sheet 13, and the reinforcing structure is continuous rectangle or semicircle, and the number of the reinforcing structure is not less than 1. The shape profile of the reinforcing structure 15 is selected to allow for cooperation with the upper and lower sheets 12, 13 and for ease of later removal.
The contact positions of the base wax pattern and the upper single sheet 12, the lower single sheet 13, the supporting structure 14 and the reinforcing structure 15 are subjected to wax pattern surface finishing and polishing, and the whole wax pattern is cleaned.
The conformal single sheets 23 are combined to a pouring gate of the integral wax mould module, and the pouring gate is additionally arranged on the lug piece 25 for supporting, so that the lug piece 25 is prevented from deforming in the pouring process.
Step 300, shell preparation
Preparation of shell
Coating surface layer slurry on the surface of the integral wax mould, and then removing the redundant surface layer slurry;
brushing or pouring the integral wax mold 1 in the area A, the integral wax mold 2 in the area B and the integral wax mold 3 in the area C, and increasing the thickness of the slurry of the surface layer in the area of the special-shaped gap hole; compared with the conventional shell preparation process, the special-shaped gap has smaller size, and whether the surface layer slurry on the surface of the wax mould in the area is uniformly coated is difficult to observe visually, so that the surface layer slurry coating is additionally added to the special-shaped gap area to ensure the quality uniformity of a surface layer directly contacted with the wax mould;
performing surface layer sand spraying on the integral wax mould, checking the sand spraying quality of the special-shaped gap hole area through a window 22, performing supplementary sand spraying on the position with local sand shortage, and then drying to form a surface layer shell;
preparation of the Back Shell
Coating back layer slurry on the surface of the surface layer type shell, and removing the redundant back layer slurry.
Removing redundant surface layer slurry or back layer slurry, accelerating slurry dripping by adopting a mode of rotating and inclining the position of the B area, then performing secondary slurry coating on the B area, and rotating and inclining again to accelerate slurry dripping; the slurry in the special-shaped gap hole area is not easy to discharge, and the slurry can be prevented from forming local accumulation in the special-shaped gap hole area by adopting a rotary inclination mode;
carrying out secondary brushing or pouring on the integral wax mold 1 in the area A, the integral wax mold 2 in the area B and the integral wax mold 3 in the area C, and increasing the thickness of the back layer slurry;
carrying out back layer sand spraying on the whole surface layer shell, and then drying to form a first back layer shell;
filling the gaps of the integral wax mold 3 in the C area through the window 22; because the size of the special-shaped gap hole area is smaller, if the special-shaped gap hole area is coated layer by layer in a conventional mode, the exposed part of the special-shaped gap hole is filled, the inside of the special-shaped gap hole is in a hollow state, the strength of the area shell is greatly reduced, the condition that the shell is locally broken in the casting filling process is easily caused, and the casting yield is reduced. The special-shaped gap hole can be filled and tamped through the window, so that the strength of the shell in the special-shaped gap hole area is enhanced;
the filling material for filling the gap of the integral wax mould 3 in the C area adopts a viscous slurry sand mixture formed by mixing back layer slurry and back layer sand;
the first and third steps in the preparation of the back shell are repeated a plurality of times to form a multi-layered back shell.
And roasting the shell to prepare the casting shell.
Step 400, smelting and pouring
The quality of the special-shaped gaps of the casting shell is detected through the window 22. The problems of local cracking, sand falling and the like of the shell are repaired, and the shell quality is improved.
Casting pouring is carried out by utilizing the casting shell, and a basic casting and a free-form single piece 23 casting are obtained.
Centrifugal casting or gravity casting is carried out by utilizing the casting shell under vacuum.
Step 500, cutting and polishing of auxiliary structure
The conformal monolith 23 is cut from the casting system.
The supporting structure 14 and the reinforcing structure 15 of the basic casting are cut and the cut edges are ground.
Step 600, welding
Performing nondestructive detection on the casting positions corresponding to the integral wax mold 2 in the area B and the integral wax mold 3 in the area C, and plugging the window 22 when no internal defect exists; when the internal defect exists, the internal defect is repaired through the window 22; the arrangement of the window 22 structure enables the closed irreparable profiled seam blind cavity which is difficult to form to be changed into a window which can carry out quality detection and defect repair in multiple processes, thereby greatly improving the quality and yield of castings.
And designing a mould according to the size of the gap between the window 22 and the integral wax mould 2 in the area B, and preparing a supporting block.
The material of the supporting block comprises: 40-50% of liquid sodium silicate and the balance of graphite powder. Drying the prepared supporting block at the temperature of 150-; drying the supporting block to form a solid with certain strength;
placing the supporting block in the gap of the window 22, then placing the conformal single sheet 23 on the surface, and plugging the window 22 by the conformal single sheet 23 in a welding mode; due to the existence of the supporting block, the size precision of the conformal single sheet 23 during welding can be ensured, and the size precision of the special-shaped clearance hole is further ensured;
and carrying out surface grinding on the outer surface of the welding area.
Step 700, partial acid washing
Soaking the supporting block by hot water or hot steam, and discharging graphite powder through the integral wax mold 1 in the area A or the integral wax mold 3 in the area C after the supporting block is crushed;
and (3) locally cleaning abnormal gaps of the integral wax mold 1 in the area A, the integral wax mold 2 in the area B and the integral wax mold 3 in the area C by adopting a hydrofluoric acid and nitric acid mixed solution, and pickling and removing the integral wax mold 2 in the area B and the integral wax mold 3 in the area C by 0.3-2 mm of the wall thickness increased than the actual wall thickness. And obtaining a final casting. The quality of the inner surface of the special-shaped gap hole can be further improved through acid washing, and the pollution of the inner surface of the special-shaped gap hole in the casting process is removed.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (10)
1. A preparation method of titanium and titanium alloy castings containing special-shaped clearance holes is provided, wherein the titanium and titanium alloy castings are provided with the special-shaped clearance holes, and is characterized by sequentially comprising the following steps: preparing a basic wax mould, preparing an integral wax mould, preparing a shell, smelting and pouring, cutting and polishing an auxiliary structure, welding and locally pickling;
wherein, the preparation of the basic wax mould comprises the following steps: according to different structures of the special-shaped clearance holes of the titanium and titanium alloy castings, the special-shaped clearance holes are divided into an A-area integral wax pattern, a B-area integral wax pattern and a C-area integral wax pattern, wherein the A-area integral wax pattern comprises: the part A area wax pattern, the upper single sheet and the lower single sheet are provided with concave butt joint grooves at the upper edge and the lower edge; the upper single sheet and the lower single sheet are provided with convex butt joint grooves matched with the concave butt joint grooves, and the B-area integral wax pattern comprises a part of B-area wax pattern and a conformal single sheet;
designing a basic wax mold preparation mold according to the structures and the sizes of the casting and the special-shaped clearance hole, and then carrying out basic wax mold preparation to form a basic wax mold provided with a part of A-area wax mold, a part of B-area wax mold and a C-area integral wax mold;
the preparation of the integral wax mould comprises the following steps: and respectively combining the upper single sheet and the lower single sheet to the upper edge and the lower edge of the partial A-area wax pattern, and performing position positioning by utilizing the concave butt joint groove and the convex butt joint groove to form an integral wax pattern.
2. The method for producing a titanium or titanium alloy casting containing a shaped clearance hole as claimed in claim 1,
a window is formed in the wax pattern of the part B area, and the window is at least provided with a lug piece;
the profile of the conformal single sheet is matched with the profile of the window;
the conformal single sheet is provided with a lug plate matched with the concave lug plate.
3. The method for producing a titanium or titanium alloy casting containing a shaped clearance hole as claimed in claim 1,
the A-zone integral wax pattern comprises: a support structure and a reinforcing structure;
the preparation of the basic wax mould comprises the following steps: cleaning the basic wax pattern and removing parting lines on the surfaces of the partial A-area wax pattern, the partial B-area wax pattern and the partial C-area integral wax pattern;
the preparation of the integral wax mould also comprises the following steps: mounting a support structure between the upper and lower monoliths; respectively installing reinforcing structures on the upper single chip and the lower single chip, and respectively connecting the upper single chip and the lower single chip with the basic wax pattern;
and combining the conformal single sheets to a pouring channel of the integral wax mould module, and adding pouring channel support to the lug positions.
4. The method for producing a titanium or titanium alloy casting containing a shaped clearance hole as claimed in claim 3,
the preparation of the integral wax mould also comprises the following steps: and performing surface finishing and polishing on the contact positions of the basic wax pattern, the upper single sheet, the lower single sheet, the supporting structure and the reinforcing structure, and cleaning the whole wax pattern.
5. The method for producing a titanium or titanium alloy casting containing a shaped clearance hole as claimed in claim 2,
the preparation of the shell comprises the following steps:
coating surface layer slurry on the surface of the integral wax mould, and then removing the redundant surface layer slurry;
brushing or pouring the integral wax pattern in the area A, the integral wax pattern in the area B and the integral wax pattern in the area C, and increasing the thickness of the slurry of the surface layer in the area of the special-shaped gap hole;
carrying out surface layer sand spraying on the integral wax mould, and drying to form a surface layer shell;
preparing a back layer shell: coating back layer slurry on the surface of the surface layer shell, and removing the redundant back layer slurry;
carrying out secondary brushing or pouring on the integral wax pattern in the area A, the integral wax pattern in the area B and the integral wax pattern in the area C, and increasing the thickness of the back layer slurry;
carrying out back layer sand spraying on the integral surface layer shell, and drying to form a first back layer shell;
filling the gap of the integral wax pattern in the area C through the window;
repeating the first and third steps of the back-layer shell preparation for a plurality of times to form a multi-layer back-layer shell;
and roasting the multilayer back layer shell mold to prepare a casting shell mold.
6. The method of making a titanium and titanium alloy casting containing shaped clearance holes of claim 5, wherein the step of removing excess backing layer slurry comprises: and accelerating the slurry dripping by adopting a mode of rotating and inclining the whole wax mold in the B area, then performing secondary slurry coating on the whole wax mold in the B area, and rotating and inclining the whole wax mold again to accelerate the slurry dripping.
7. The method for preparing a titanium and titanium alloy casting containing a profiled clearance hole as claimed in claim 5, wherein the step of filling the clearance of the C-zone integral wax pattern comprises:
and the filler for filling the gap of the integral wax mould in the C area is a viscous slurry sand mixture formed by mixing back layer slurry and back layer sand.
8. The method for producing a titanium or titanium alloy casting containing a shaped clearance hole as claimed in claim 1,
the smelting and pouring method comprises the following steps:
detecting the quality of the special-shaped gap of the casting shell through a window;
casting pouring is carried out by utilizing a casting shell to obtain a basic casting and a free-form single-piece casting;
centrifugal casting or gravity casting is carried out by utilizing the casting shell under vacuum.
9. The method for producing a titanium or titanium alloy casting containing a shaped clearance hole as claimed in claim 3,
the auxiliary structure cutting and polishing comprises the following steps: cutting a free-form single sheet from a gating system, cutting a supporting structure and a reinforcing structure of a basic casting, and polishing the cut edge;
the welding comprises the following steps: performing nondestructive detection on the casting positions corresponding to the integral wax pattern in the area B and the integral wax pattern in the area C, and plugging the window when no internal defect exists; when the internal defect exists, the internal defect is repaired through the window;
designing a mold according to the sizes of the gaps of the window and the integral wax mold in the area B, and preparing a supporting block;
the material of the supporting block comprises: 40-50% of liquid sodium silicate and the balance of graphite powder, and drying the prepared supporting block at the temperature of 150-;
placing the supporting block in a gap of the window, then placing a random type single sheet on the surface, and plugging the window by the random type single sheet in a welding mode;
and carrying out surface grinding on the outer surface of the welding area.
10. The method for producing a titanium and titanium alloy casting containing a shaped clearance hole as claimed in claim 9,
the local pickling comprises the following steps:
soaking the supporting block, and discharging graphite powder through the integral wax mold in the area A or the integral wax mold in the area C after the supporting block is crushed;
and (3) locally cleaning the special-shaped clearance holes of the integral wax mold in the area A, the integral wax mold in the area B and the integral wax mold in the area C by adopting a hydrofluoric acid and nitric acid mixed solution, and pickling and removing the integral wax mold in the area B and the integral wax mold in the area C by 0.3-2 mm of the wall thickness increased than the actual wall thickness to obtain a final casting.
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