Machining method of capsule-shaped flat tube thin-wall titanium alloy supporting column

Abstract

The invention discloses a processing method of a capsule-shaped flat tube thin-wall titanium alloy supporting column. The processing method comprises the steps of selecting a blank material type, designing and manufacturing a forming die, calculating the size of the blank material, assembling the die, forming parts and processing the appearance. According to the method, a titanium alloy round pipe with the same wall thickness as a capsule-shaped flat pipe thin-wall titanium alloy supporting column part and the same section area perpendicular to the axis direction is selected as a blank material, a positioning section is additionally arranged outside the blank material, thermal forming is conducted in cooperation with a forming die, then descaling treatment is conducted on the surface of the cooled part, and the capsule-shaped flat pipe thin-wall titanium alloy supporting column part is obtained. And finally, the final boundary dimension is obtained in a machining mode. A weldless forming machining method is selected, a used forming die is reliable and effective, and meanwhile the size precision and the machining quality of the part can be effectively guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical processing, and in particular relates to a processing method of a capsule-shaped flat tube thin-wall titanium alloy pillar. Background Art

[0002] The intermediate casing is an important part of the aircraft engine, connecting the fan and high-pressure compressor and other parts. The thin-walled titanium alloy pillars play a vital role in the intermediate casing. They not only provide structural support for the intermediate casing, but also guide and optimize the airflow. The schematic diagram of its parts structure is shown in the figure below. Figure 1 shown.

[0003] At present, the processing plan for thin-walled titanium alloy pillars is to use titanium alloy sheets to semi-hot-form into a U-shaped semi-capsule shape, then cut and trim the U-shaped excess and weld it into a capsule shape, then grind the weld and perform heat correction to ensure the part surface, and finally process the outer dimensions.

[0004] The above processing scheme has the following processing difficulties and hidden dangers:

[0005] (1) When removing the U-shaped excess, it is difficult to ensure the consistency of the gap between the welding butt end faces, resulting in unstable welding quality;

[0006] (2) The inner cavity width of the capsule-shaped flat tube thin-walled titanium alloy support is narrow (about 10 mm) and the length is about 200 mm. It is difficult to implement gas protection measures during welding, and the weld nodules in the capsule-shaped cavity are difficult to polish smooth after welding;

[0007] (3) Welding deformation requires thermal calibration to ensure the part profile, which prolongs the processing time, increases the processing cost of the parts, and extends the pillar delivery cycle.

[0008] Based on the above reasons, it is necessary to propose a processing method for capsule-shaped flat tube thin-walled titanium alloy pillars to overcome the difficulties and hidden dangers listed in (1) to (3) and meet the quality requirements of part shape and dimensional accuracy. Summary of the invention

[0009] The present invention aims to provide a method for processing a capsule-shaped flat tube thin-wall titanium alloy pillar, adopts a weld-free forming method, uses a reliable and effective forming mold, and can effectively ensure the dimensional accuracy and processing quality of the parts.

[0010] To achieve the above object, the present invention adopts the following technical solutions:

[0011] A method for processing a capsule-shaped flat tube thin-wall titanium alloy pillar, comprising:

[0012] Select the blank material type, and use a titanium alloy round tube with the same wall thickness and the same cross-sectional area perpendicular to the axis direction as the capsule-shaped flat tube thin-walled titanium alloy pillar part as the blank material;

[0013] Design and manufacture of forming molds. According to the size and shape requirements of the capsule-shaped flat tube thin-walled titanium alloy pillar parts, the forming molds are designed and manufactured. The forming molds are mainly composed of an upper mold plate, a lower mold plate, an upper mold and a lower mold plate. The upper mold cavity of the upper mold includes a first U-shaped forming cavity and a first positioning cavity. The lower mold cavity of the lower mold includes a second U-shaped forming cavity and a second positioning cavity. The parting surface of the first U-shaped forming cavity and the second U-shaped forming cavity corresponds to the bisecting plane of the axis of the capsule-shaped flat tube thin-walled titanium alloy pillar. The first positioning cavity and the second positioning cavity form a cylindrical cavity.

[0014] Calculate the size of the blank material, based on the axial length and wall thickness of the capsule-shaped flat tube thin-walled titanium alloy pillar part, take the axial length and wall thickness consistent with the axial length and wall thickness of the capsule-shaped flat tube thin-walled titanium alloy pillar part, and calculate the blank size of the titanium alloy round tube blank material according to the principle of constant volume, including the inner diameter ΦD2 and the outer diameter ΦD1, and then add an additional positioning length L2 on the basis of the axial length of the titanium alloy round tube blank material;

[0015] Assemble the mold, first assemble and fix the lower mold on the lower mold plate, then fix the lower mold plate on the lower platform of the forming machine, then assemble and fix the upper mold on the upper mold plate, and then fix the upper mold plate on the upper platform of the forming machine;

[0016] Forming parts, placing the titanium alloy round tube blank material into the lower die, and placing a section of the titanium alloy round tube blank material corresponding to the positioning length L2 in the second positioning cavity of the lower die of the forming die, and the remaining part is located in the second U-shaped forming cavity, heating the titanium alloy round tube blank material and preheating the forming die, raising the temperature to the hot forming temperature, and then moving the press equipment downward to apply pressure to complete the upper and lower dies and perform hot forming, keeping the temperature and pressure for a period of time, and then cooling and opening the die to obtain a capsule-shaped flat tube thin-walled titanium alloy pillar, and performing surface treatment on the cooled capsule-shaped flat tube thin-walled titanium alloy pillar;

[0017] Shape processing: according to the required dimensions of the capsule-shaped flat tube thin-walled titanium alloy pillar part drawing, its shape is processed until the required design dimensions are obtained.

[0018] As an option, when selecting the blank material type, titanium alloy bars or titanium alloy round tubes with inconsistent diameters are used as blank materials by machining the inner and outer circles to remove excess material and process them into titanium alloy round tubes with the same wall thickness and cross-sectional area perpendicular to the axis.

[0019] As an option, when the forming mold is designed and manufactured, the volume of the first positioning cavity is greater than the volume of the second positioning cavity.

[0020] As an option, when the forming die is designed and manufactured, the inner diameter of the cylindrical cavity formed by the first positioning cavity and the second positioning cavity is equal to the outer diameter ΦD1 of the titanium alloy round tube blank material.

[0021] As an option, when the forming mold is designed and manufactured, the sum of the lengths of the first U-shaped forming cavity and the first positioning cavity and the sum of the lengths of the second U-shaped forming cavity and the second positioning cavity is greater than the sum of the axial length of the capsule-shaped flat tube thin-walled titanium alloy pillar part and the positioning length L2.

[0022] As an option, after assembling the mold and before forming the parts, the upper and lower mold surfaces in the forming mold are coated with boron nitride protective coating, and the titanium alloy round tube blank material is surface cleaned and coated with boron nitride protective coating.

[0023] As an option, when forming the part, the preheating temperature of the forming die is 70% to 80% of the heating temperature of the titanium alloy round tube blank material.

[0024] As an option, when forming the part, the hot forming temperature is 870°C ± 10°C, the press equipment moves downward and applies a pressure of 1.5 to 6T, the heat preservation and pressure holding time is 16 to 20 minutes, and then the part and the forming mold are naturally cooled.

[0025] As an option, when forming the part, the surface treatment of the cooled capsule-shaped flat tube thin-walled titanium alloy pillar includes first removing the surface oxide layer by sand blasting and then removing the surface oxide layer by pickling.

[0026] Compared with the traditional scheme, the processing scheme of the capsule-shaped flat tube thin-walled titanium alloy pillar provided by the present invention does not require the parts to be processed through welding, grinding, heat correction and other processes. Therefore, the processed products do not have welding defects such as undercut, weld bead, slag inclusion, air hole and the like, and there is no problem of weld cracking during forming. The processing method of the present invention is more reliable, and the processed parts have better consistency and higher quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of a capsule-shaped flat tube thin-walled titanium alloy support column in the present invention;

[0028] Figure 2 It is a schematic diagram of the forming die structure in the present invention;

[0029] Figure 3 It is a schematic diagram of the titanium alloy round tube blank material in the present invention;

[0030] Figure 4It is a schematic diagram of a part formed in the present invention;

[0031] In the figure, 1-upper template, 2-lower template, 3-upper mold, 4-lower mold. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to common technical knowledge and customary means in the field are included in the scope of the present invention.

[0033] The basic idea of ​​the capsule-shaped flat tube thin-walled titanium alloy pillar processing method of the present invention is as follows:

[0034] Step 1: Select the blank material type. When the titanium alloy pillar is processed by plate, it needs to be welded. Welding will cause problems such as the appearance quality of the parts and unstable welding quality. Therefore, if welding is to be avoided, round tubes with the same material thickness as the parts need to be used.

[0035] Step 2: Design and manufacture of forming molds, such as Figure 2 As shown, according to the size and shape requirements of the titanium alloy pillar, a forming mold structure is designed and manufactured. The mold is generally composed of an upper mold plate 1, a lower mold plate 2, a mold 3 and a lower mold 4. The forming cavities of the upper mold 3 and the lower mold 4 are arranged according to Figure 1 The horizontal bisector of the CC section is split into two cavities, upper and lower.

[0036] Step 3: Calculate the blank size, such as Figure 3 As shown, according to the principle that the processing volume of pillars with the same length remains unchanged, the inner and outer diameters of the blank round tube are calculated to be ΦD2 and ΦD1 respectively, the bottom area of ​​the blank round tube is S1, and the length is L1.

[0037] Step 4: Assemble the mold. First, assemble and fix the lower mold 4 on the lower mold plate 2, and then fix the lower mold plate 2 on the lower platform of the forming machine. Then, assemble and fix the upper mold 3 on the upper mold plate 1, and then fix the upper mold plate 1 on the upper platform of the forming machine.

[0038] Step 5: Forming parts, placing the L2 section of the pre-treated blank round tube L1 in the clamping and positioning half groove ΦD1 of the lower die 4 of the pre-treated mold, heating the blank round tube and preheating the mold to the hot forming temperature of 870℃±10℃, and then moving the press equipment downward to apply pressure to complete the hot forming of the upper die 3 and the lower die 4, and performing surface treatment on the flat tube after cooling;

[0039] Step 6: Figure 4, process the shape of the part according to its required size, and remove the excess shape by cutting or other machining methods.

[0040] Further, in step 1, the blank material types include plates, bars, tubes, strips, etc. When welding is to be avoided in the processing of titanium alloy pillars, thin-walled tubes with the same wall thickness and bottom area (the bottom area here refers to the cross-sectional area perpendicular to the axis of the round tube) are preferably used for processing; in addition, bars or round tubes with different diameters can be selected to remove excess material by turning the inner and outer circles, and processed into round tubes with the same wall thickness and bottom area as the pillars;

[0041] Further, in step 2, the cavity with a length of L2 in the lower die 3 in the forming die structure is used for clamping and positioning the blank round tube, and the diameter of the clamping and positioning position is the same as the diameter of the blank round tube, that is, ΦD1; this positioning clamping makes the round tube located in the middle of the capsule-shaped groove, and when the press machine applies downward pressure, the round tube can be uniformly deformed to the two ends of the capsule shape into a flat tube; at the same time, the length of the forming surface of the forming die should be ≥ L1 to ensure that the entire shape of the part is processed in place during forming;

[0042] Further, in step 3, the length L1 of the blank round tube satisfies that the wall thickness is equal to the wall thickness of the pillar, that is, (ΦD1-ΦD2) / 2; the bottom area S1 of the blank round tube should be equal to the bottom area S of the pillar, that is, S1=S; the length used for processing parts is L, the length for clamping and positioning is L2, and the length of the blank round tube is L2+L=L1.

[0043] Further, in step 5, the pre-treated blank round tube and the forming mold are cleaned, and the oil stains and impurities on the surface of the round tube and the mold are removed with an organic solvent, and the outer circle of the blank round tube is brushed with a boron nitride protective coating, and the upper mold 3 and the lower mold 4 of the mold are brushed with a boron nitride protective coating, and naturally dried at room temperature;

[0044] Furthermore, the forming mold preheating treatment is to preheat the forming mold while heating the round tube, so as to reduce the temperature difference between the round tube and the forming mold and prevent defects such as cold shut during the forming process. The forming mold preheating temperature is 70% to 80% of the round tube heating temperature.

[0045] Further, in step 5, the hot forming temperature is 870°C ± 10°C, the equipment pressure is 1.5 to 6T (tons), the heat preservation and pressure holding time is 16 to 20 minutes, and then the part and the forming mold are naturally cooled;

[0046] Furthermore, in step 5, the surface treatment is to treat the surface of the formed flat tube, firstly, sand blasting is used to remove the thick oxide layer on the surface of the flat tube, and then pickling is performed to accurately remove the oxide layer on the surface of the flat tube to ensure the surface roughness of the finished product.

[0047] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. Although the illustrative specific embodiments of the present invention are described above to facilitate the understanding of the present invention by the technical personnel in the field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For ordinary technicians in the field of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A method for processing a capsule-shaped flat tube thin-walled titanium alloy pillar, characterized in that: include: Select the blank material type, and use a titanium alloy round tube with the same wall thickness and the same cross-sectional area perpendicular to the axis direction as the capsule-shaped flat tube thin-walled titanium alloy pillar part as the blank material; Design and manufacture of a forming mold. According to the size and shape requirements of the capsule-shaped flat tube thin-walled titanium alloy pillar part, the forming mold is designed and manufactured. The forming mold mainly consists of an upper mold plate (1), a lower mold plate (2), an upper mold (3) and a lower mold (4). The upper mold cavity of the upper mold (3) includes a first U-shaped forming cavity and a first positioning cavity. The lower mold cavity of the lower mold (4) includes a second U-shaped forming cavity and a second positioning cavity. The parting surface of the first U-shaped forming cavity and the second U-shaped forming cavity corresponds to a bisecting plane passing through the axis of the capsule-shaped flat tube thin-walled titanium alloy pillar. The first positioning cavity and the second positioning cavity form a cylindrical cavity. Calculate the size of the blank material, based on the axial length and wall thickness of the capsule-shaped flat tube thin-walled titanium alloy pillar part, take the axial length and wall thickness consistent with the axial length and wall thickness of the capsule-shaped flat tube thin-walled titanium alloy pillar part, and calculate the blank size of the titanium alloy round tube blank material according to the principle of constant volume, including the inner diameter ΦD2 and the outer diameter ΦD1, and then add an additional positioning length L2 on the basis of the axial length of the titanium alloy round tube blank material; Assembling the mold, first assembling and fixing the lower mold (4) on the lower mold plate (2), then fixing the lower mold plate (2) on the lower platform of the forming machine, then assembling and fixing the upper mold (3) on the upper mold plate (1), and then fixing the upper mold plate (1) on the upper platform of the forming machine; Forming parts, placing a titanium alloy round tube blank material into a lower die (4), and placing a section of the titanium alloy round tube blank material corresponding to a positioning length L2 in a second positioning cavity of the lower die (4) of the forming die, and the remaining section in a second U-shaped forming cavity, heating the titanium alloy round tube blank material and preheating the forming die to a hot forming temperature, and then moving a press machine downward to apply pressure to complete the mold closing of the upper die (3) and the lower die (4) and perform hot forming, keeping the temperature and pressure for a period of time, and then cooling and opening the die to obtain a capsule-shaped flat tube thin-walled titanium alloy pillar, and performing surface treatment on the cooled capsule-shaped flat tube thin-walled titanium alloy pillar; Shape processing: according to the required dimensions of the capsule-shaped flat tube thin-walled titanium alloy pillar part drawing, its shape is processed until the required design dimensions are obtained.

2. The method for processing a capsule-shaped flat tube thin-walled titanium alloy pillar according to claim 1, characterized in that: When selecting the blank material type, titanium alloy bars or titanium alloy round tubes with inconsistent diameters are used as blank materials by machining the inner and outer circles to remove excess material and processing them into titanium alloy round tubes with the same wall thickness and cross-sectional area perpendicular to the axis.

3. The method for processing a capsule-shaped flat tube thin-walled titanium alloy pillar according to claim 1, characterized in that: When the forming mold is designed and manufactured, the volume of the first positioning cavity is greater than the volume of the second positioning cavity.

4. The method for processing a capsule-shaped flat tube thin-walled titanium alloy pillar according to claim 1, characterized in that: When the forming die is designed and manufactured, the inner diameter of the cylindrical cavity formed by the first positioning cavity and the second positioning cavity is equal to the outer diameter ΦD1 of the titanium alloy round tube blank material.

5. The method for processing a capsule-shaped flat tube thin-walled titanium alloy pillar according to claim 1, characterized in that: When the forming mold is designed and manufactured, the sum of the lengths of the first U-shaped forming cavity and the first positioning cavity and the sum of the lengths of the second U-shaped forming cavity and the second positioning cavity are greater than the sum of the axial length of the capsule-shaped flat tube thin-walled titanium alloy pillar part and the positioning length L2.

6. The method for processing a capsule-shaped flat tube thin-walled titanium alloy pillar according to claim 1, characterized in that: After the mold is assembled and before the parts are formed, the surfaces of the upper mold (3) and the lower mold (4) in the forming mold are coated with boron nitride protective coating, and the surface of the titanium alloy round tube blank material is cleaned and coated with boron nitride protective coating.

7. The method for processing a capsule-shaped flat tube thin-walled titanium alloy pillar according to claim 1, characterized in that: When forming the parts, the preheating temperature of the forming die is 70% to 80% of the heating temperature of the titanium alloy round tube blank material.

8. The method for processing a capsule-shaped flat tube thin-walled titanium alloy pillar according to claim 1, characterized in that: When forming the parts, the hot forming temperature is 870°C±10°C, the press equipment moves downward and applies a pressure of 1.5-6T, the heat preservation and pressure holding time is 16-20min, and then the parts and the forming mold are naturally cooled.

9. The method for processing a capsule-shaped flat tube thin-walled titanium alloy pillar according to claim 1, characterized in that: When forming the parts, the surface treatment of the cooled capsule-shaped flat tube thin-wall titanium alloy pillar includes firstly removing the surface oxide layer by sand blasting and then removing the surface oxide layer by pickling.

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