A method for forming a drum-shaped variable wall thickness titanium alloy revolution body tubular

Abstract

A kind of forming method of drum-shaped variable wall thickness titanium alloy rotary tube, solve the wall thickness uniformity control technical problem of tube, improve product adaptability and production efficiency, reduce production cost.It includes:(1) bar diameter forging: titanium alloy bar is selected as raw material, after whole heating and heat preservation in box resistance furnace, the middle of bar is pulled long by diameter forging machine, variable diameter bar blank is prepared, and air cooling is carried out after diameter forging;(2) mechanical processing: variable diameter bar blank is drilled and bored, then the outer surface of tube blank is turned to obtain equal internal diameter variable wall thickness tube blank;(3) tube blank diameter forging: local heating is carried out on the end of equal internal diameter variable wall thickness tube blank by induction heating method, then diameter forging is carried out on the heated part to obtain variable diameter variable wall thickness tube blank, and air cooling is carried out after diameter forging;(4) mechanical processing: the part after tube blank diameter forging is mechanically processed to obtain drum-shaped variable wall thickness titanium alloy rotary tube.

Description

Technical Field

[0001] This invention relates to the technical field of titanium alloy tube manufacturing, and in particular to a forming method for a drum-shaped variable wall thickness titanium alloy rotating tubular component. Background Technology

[0002] The drum-shaped variable-wall-thickness titanium alloy rotary tubular component is mainly used in the manufacture of tie rods for integrated aircraft. The component features a thin-walled tube of uniform diameter and wall thickness in the middle, and thick-walled irregularly shaped tubes of varying diameter and wall thickness at both ends. This design aims to meet the forming requirements of the integrated tie rod structure. Tie rods operate under complex conditions, with high requirements for tensile and compressive loads, tensile and compressive fatigue, and vibration resistance, and there is an urgent need for reliability and lightweight design. The thin-walled section in the middle of the drum-shaped variable-wall-thickness titanium alloy rotary tubular component is a weak point. To ensure the reliability and service life of the tie rod while achieving maximum weight reduction, strict control over the wall thickness and uniformity of the thin-walled portion of the titanium alloy tubular component is necessary. The forming difficulty of the variable-wall-thickness tubular component lies in maintaining the dimensions of the thin-walled tube during the forming of the thick-walled irregularly shaped tube. Due to the poor formability of titanium alloy, this significantly increases the forming difficulty.

[0003] Patent application CN102700668 A discloses a seamless titanium alloy variable wall thickness tube and its radial forging forming mechanism and method. It uses a tube of uniform wall thickness as the blank, employs a mandrel for localized rotary forging and drawing, and then performs mandrel-less rotary forging of the thick-walled section. Patent application CN 112170773 A discloses a near-net-shape precision forging technology for a lightweight alloy non-rotating integral tie rod. The tie rod blank also uses a tube of uniform wall thickness. The middle section of the blank is first precision forged and drawn, and then the thick-walled section is precision forged. Both precision forging deformations use a mandrel. Both patents employ tube drawing with a mandrel. Due to the characteristics of their process, it is impossible to precisely control the wall thickness uniformity of the thin-walled section in subsequent processing. To ensure the reliability of the tie rod, the wall thickness must be increased, which is detrimental to the tie rod's lightweight requirements. Furthermore, the thin-walled connecting rod is relatively long, and the rapid temperature drop during the hot drawing process of the blank increases the forming difficulty. The two patents mentioned above use equal-diameter, equal-wall-thickness tube blanks to produce equal-outer-diameter, variable-wall-thickness tubes through continuous hot forming. After forming, the oxide layer cannot be removed from the inner surface by machining, leading to reduced reliability at thin-walled sections. Because their equal-outer-diameter tubes are formed with mandrels, different sizes of mandrels are required for different tube specifications, resulting in low process adaptability and increased production costs. Furthermore, patent application CN 112170773 A involves two precision forging processes that require changing the hammer and mandrel, making the process complex and inefficient. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a forming method for a drum-shaped variable wall thickness titanium alloy rotating tubular part, which solves the technical problem of controlling the wall thickness uniformity of the tubular part, improves product adaptability and production efficiency, and reduces production costs.

[0005] The technical solution of this invention is: a forming method for this drum-shaped variable wall thickness titanium alloy rotating tubular part, which includes the following steps:

[0006] (1) Bar forging: Titanium alloy bars are selected as raw materials. After the bars are heated and kept warm in a box-type resistance furnace, the middle of the bars are forged and drawn out using a forging machine to prepare variable diameter billets. After forging, the bars are air-cooled.

[0007] (2) Machining: Drilling and boring are performed on the variable diameter bar billet, and then the outer surface of the tube billet is turned to obtain a tube billet with constant inner diameter and variable wall thickness.

[0008] (3) Pipe blank diameter forging: The end of the pipe blank with equal inner diameter and variable wall thickness is locally heated by induction heating, and then the heated part is diameter forged to obtain a pipe blank with variable diameter and variable wall thickness. After diameter forging, it is air cooled.

[0009] (4) Machining: Machining is performed on the part of the tube blank after forging to obtain a drum-shaped variable wall thickness titanium alloy rotating tube.

[0010] This invention employs a combination of bar forging and machining to prepare a tube blank with a constant inner diameter and variable wall thickness. The process is simple, with low forming difficulty, allowing for precise control of the tube blank's wall thickness and uniformity, ensuring surface quality, improving tube reliability, and maximizing the achievement of lightweight tie rod requirements. This invention uses induction heating for localized heating at both ends of the tube blank, preventing the thin-walled portion and the outermost thick-walled section from participating in deformation, thus improving production efficiency. The tube component of this invention features a variable outer diameter design, with the outermost portion directly used to form tie rod lugs. Its wall thickness is smaller than that of blanks used in existing processes, reducing forming difficulty and achieving lightweight requirements while meeting lug structure forming requirements. This invention uses coreless bar forging, resulting in strong product specification adaptability while reducing production costs and increasing production efficiency. Therefore, this invention solves the technical problem of controlling the wall thickness uniformity of tube components, improving product adaptability and production efficiency, and reducing production costs. Attached Figure Description

[0011] Figure 1 This is a diagram illustrating the shape and working principle of the radial forging machine hammer of the present invention.

[0012] Figure 2 This is a schematic diagram of the variable diameter bar forging and drawing process of the present invention.

[0013] Figure 3This is a schematic diagram of the machining process for a tube blank with constant inner diameter and variable wall thickness according to the present invention.

[0014] Figure 4 This is a schematic diagram of the local diameter forging process of the variable diameter and variable wall thickness tube blank according to the present invention.

[0015] Figure 5 This is a schematic diagram of the machining process for the drum-shaped variable wall thickness titanium alloy tubular part of the present invention.

[0016] Figure 6 This is a flowchart of the forming method of the drum-shaped variable wall thickness titanium alloy rotating tubular part of the present invention.

[0017] in:

[0018] 1—Titanium alloy bar stock; 2—Polar forging mill hammer; 3—Polar forging mill jaws;

[0019] 4—Variable diameter bar billet; 5—Drill bit / boring tool; 6—Lathe tool;

[0020] 7—Constant inner diameter, variable wall thickness tube blank; 8—Induction heating coil; 9—Variable diameter, variable wall thickness tube blank;

[0021] 10—Drum-shaped variable wall thickness titanium alloy tubular parts. Detailed Implementation

[0022] like Figure 6 As shown, the forming method of this drum-shaped variable wall thickness titanium alloy rotary tubular part includes the following steps:

[0023] (1) Bar forging: Titanium alloy bars are selected as raw materials. After the bars are heated and kept warm in a box-type resistance furnace, the middle of the bars are forged and drawn out using a forging machine to prepare variable diameter billets. After forging, the bars are air-cooled.

[0024] (2) Machining: Drilling and boring are performed on the variable diameter bar billet, and then the outer surface of the tube billet is turned to obtain a tube billet with constant inner diameter and variable wall thickness.

[0025] (3) Pipe blank diameter forging: The end of the pipe blank with equal inner diameter and variable wall thickness is locally heated by induction heating, and then the heated part is diameter forged to obtain a pipe blank with variable diameter and variable wall thickness. After diameter forging, it is air cooled.

[0026] (4) Machining: Machining is performed on the part of the tube blank after forging to obtain a drum-shaped variable wall thickness titanium alloy rotating tube.

[0027] This invention employs a combination of bar forging and machining to prepare a tube blank with a constant inner diameter and variable wall thickness. The process is simple, with low forming difficulty, allowing for precise control of the tube blank's wall thickness and uniformity, ensuring surface quality, improving tube reliability, and maximizing the achievement of lightweight tie rod requirements. This invention uses induction heating for localized heating at both ends of the tube blank, preventing the thin-walled portion and the outermost thick-walled section from participating in deformation, thus improving production efficiency. The tube component of this invention features a variable outer diameter design, with the outermost portion directly used to form tie rod lugs. Its wall thickness is smaller than that of blanks used in existing processes, reducing forming difficulty and achieving lightweight requirements while meeting lug structure forming requirements. This invention uses coreless bar forging, resulting in strong product specification adaptability while reducing production costs and increasing production efficiency. Therefore, this invention solves the technical problem of controlling the wall thickness uniformity of tube components, improving product adaptability and production efficiency, and reducing production costs.

[0028] Preferably, in step (1), the bar forging is performed by heating the titanium alloy bar to 820℃~920℃ in a box-type resistance furnace and holding it for 60min~100min. Only the middle section of the bar is forged and drawn to obtain a variable diameter bar billet with large diameters at both ends and small diameter in the middle section. The bar billet is then air-cooled after forging.

[0029] Preferably, in step (2), the machining is to use a deep hole drilling machine to drill and bore the variable diameter bar blank to obtain a tube blank that meets the inner diameter requirements of the finished product; then, a centerless lathe is used to turn the outer surface of the tube blank, wherein the middle section of the tube blank is turned to the finished wall thickness size, and finally a tube blank with equal inner diameter and variable wall thickness with inner and outer surface roughness Ra≤1.6 is obtained.

[0030] Preferably, in step (3), the forging machine jaws send one end of the tube blank to the induction heating coil for online local heating. After heating to 820℃~920℃, the induction heating coil quickly withdraws from the forging line, and the tube blank is sent to the center of the forging machine hammer for end forging. The tube blank is forged to an outer diameter 2~4mm larger than the middle section of the tube blank. The other end of the tube blank is formed in the same way to obtain a tube blank with variable diameter and variable wall thickness. After forging, the tube blank is air-cooled.

[0031] Preferably, in step (4), the machining is performed by turning the part of the tube blank after diameter forging using a centerless lathe to obtain a drum-shaped variable wall thickness titanium alloy rotary tube with a surface roughness Ra≤1.6.

[0032] The following details specific embodiments of the present invention.

[0033] This invention employs a four-hammer forging machine for radial forging, using a universal hammer with a flat working surface. Its working principle is as follows: Figure 1As shown, the billet 1 rotates axially at a certain speed and is fed to the center of the four hammers 2 of the radial forging machine. The hammers forge the billet into shape at a frequency of 600 to 800 times per minute.

[0034] The variable diameter bar blank preparation process of the present invention is as follows: Figure 2 As shown. Select a titanium alloy bar 1 of appropriate grade and size according to product requirements. After heating and holding the bar 1 in a box-type resistance furnace, it is sent to the center of the hammer head 2 by the jaws 3 of the radial forging machine. The hammer head 2 performs high-frequency forging and lengthening on the middle section of the bar 1 to obtain a variable diameter billet 4 with large diameter at both ends and small diameter in the middle section. After forging, it is air-cooled.

[0035] The preparation process of the tube blank with constant inner diameter and variable wall thickness of the present invention is as follows: Figure 3 As shown. First, select the appropriate size drill bit / boring tool 5 according to the product size to drill and bore the variable diameter bar blank 4 to obtain an inner diameter hole with a surface roughness Ra≤1.6; finally, use the turning tool 6 to perform outer surface turning with a roughness Ra≤1.6, with the middle section turned to the finished size, and finally obtain a tube blank 7 with equal inner diameter and variable wall thickness.

[0036] The process for preparing the variable diameter and variable wall thickness tube blank of the present invention is as follows: Figure 4 As shown, the forging machine's jaws 3 feed one end of the tube blank 7 into the induction heating coil 8 for localized heating. After reaching the set temperature, the induction heating coil 8 quickly withdraws from the forging line, and the tube blank 7 is fed to the center of the forging machine's hammer 2 for end forging. The tube blank is forged until its outer diameter is 2-4 mm larger than the middle section of the tube blank. The other end of the tube blank 7 is formed in the same way, ultimately obtaining a variable diameter, variable wall thickness tube blank 9. The tube blank is then air-cooled after forging.

[0037] The manufacturing process of the drum-shaped variable wall thickness titanium alloy tubular component of the present invention is as follows: Figure 5 As shown, the inner and outer surfaces of the 9-diameter forging section of the tube blank are machined using a lathe, with the outer diameter matching the middle section of the tube blank, ultimately obtaining a drum-shaped variable wall thickness titanium alloy tube 10 with a surface roughness Ra≤1.6.

[0038] Example 1

[0039] This embodiment includes the following steps:

[0040] Step 1: Bar forging: Select TC4 titanium alloy bars with a specification of Φ70×700mm, heat them to 920℃ using a box-type resistance furnace, and hold for 60 minutes. After the bars are removed from the furnace, they are fed to the forging line using an automatic feeder. The chucks feed the bars to the center of the forging machine hammer, and the middle 300mm of the bars are forged and lengthened in one pass. The diameter after forging is Φ54mm, thus preparing a variable diameter billet.

[0041] Step 2, Machining: Drilling and boring are performed along the axial center of the variable diameter bar blank to obtain a tube blank with an inner diameter of Φ46mm. Then, the outer surface of the tube blank is turned to obtain a tube blank with a constant inner diameter and variable wall thickness with a surface roughness Ra≤1.6. The middle section dimension is Φ50×δ2mm and the dimensions of both ends are Φ66×δ10mm.

[0042] Step 3: Tube Billet Radial Forging: The induction heating coil is moved to the radial forging working line. The grippers feed the variable wall thickness tube billet into the induction heating coil, heating a 100mm long thick-walled section near the middle of the tube billet. After heating to 920℃, the grippers pull out the tube billet, and the induction heating coil is quickly moved out of the radial forging working line. The grippers then feed the tube billet to the center of the radial forging hammer for radial forging deformation of the heated part. After forging, it is air-cooled, and the forged size is Φ52×δ10mm. The other end of the tube billet is radially forged in the same way to finally obtain a variable diameter, variable wall thickness tube billet.

[0043] Step 4: Machining: The part of the tube blank after radial forging is machined by turning, with a surface roughness Ra≤1.6, and finally a drum-shaped variable wall thickness titanium alloy tube with a middle section size of Φ50×δ2mm, a radial forging section size of Φ50×δ6mm, and a thick wall section size of Φ66×δ10mm is obtained.

[0044] Example 2

[0045] This embodiment includes the following steps:

[0046] Step 1: Bar forging: Select TC4 titanium alloy bars with a specification of Φ84×800mm, heat them to 920℃ using a box-type resistance furnace, and hold for 70 minutes. After the bars are removed from the furnace, they are fed to the forging line using an automatic feeder. The chucks feed the bars to the center of the forging machine hammer, and the middle 400mm of the bars are forged and lengthened in one pass. The diameter of the middle section after forging is Φ64mm, thus preparing a variable diameter bar billet.

[0047] Step 2, Machining: Drill and bore along the axial center of the variable diameter bar blank to obtain a tube blank with an inner diameter of Φ55mm. Then, turn the outer surface of the tube blank to obtain a tube blank with a constant inner diameter and variable wall thickness with a surface roughness Ra≤1.6, wherein the dimensions are Φ60×δ2.5mm and the dimensions at both ends are Φ80×δ12.5mm.

[0048] Step 3: Tube Billet Radial Forging: The induction heating coil is moved to the radial forging working line. The grippers feed the variable wall thickness tube billet into the induction heating coil, heating a 100mm long thick-walled section near the middle of the tube billet. After heating to 920℃, the grippers pull out the tube billet, and the induction heating coil is quickly moved out of the radial forging working line. The grippers then feed the tube billet to the center of the radial forging hammer for radial forging deformation of the heated part. After forging, it is air-cooled, and the diameter after forging is Φ62×δ12.5mm. The other end of the tube billet is radially forged in the same way to finally obtain a variable diameter, variable wall thickness tube billet.

[0049] Step 4: Machining: The tube blank after radial forging is machined by turning, with a surface roughness Ra≤1.6, and finally a drum-shaped variable wall thickness titanium alloy tube with a middle section size of Φ60×δ2.5mm, a radial forging section size of Φ60×δ8.5mm, and a thick wall section size of Φ80×δ12.5mm is obtained.

[0050] Example 3

[0051] This embodiment includes the following steps:

[0052] Step 1: Bar forging: Select TC18 titanium alloy bars with a specification of Φ134×800mm, heat them to 840℃ in a box-type resistance furnace, and hold for 100 minutes. After the bars are removed from the furnace, they are fed to the forging line by an automatic feeder. The chucks feed the bars to the center of the forging machine hammer, and the middle 500mm of the bars are forged and drawn in one pass. The diameter of the middle section after forging is Φ104mm, thus preparing a variable diameter bar billet.

[0053] Step 2, Machining: Drilling and boring are performed along the axial center of the variable diameter billet to obtain a tube blank with an inner diameter of Φ90mm. Then, the outer surface of the tube blank is turned to obtain a tube blank with a constant inner diameter and variable wall thickness with a surface roughness Ra≤1.6, wherein the dimensions are Φ100×δ5mm and the dimensions at both ends are Φ130×δ20mm.

[0054] Step 3: Tube Billet Radial Forging: The induction heating coil is moved to the radial forging working line. The grippers feed the variable wall thickness tube billet into the induction heating coil, heating a 150mm long thick-walled section near the middle of the tube billet. After heating to 840℃, the grippers pull out the tube billet, and the induction heating coil is quickly moved out of the radial forging working line. The grippers then feed the tube billet to the center of the radial forging hammer for radial forging deformation of the heated part. After forging, it is air-cooled, and the diameter after forging is Φ102×δ20mm. The other end of the tube billet is radially forged in the same way to finally obtain a variable diameter, variable wall thickness tube billet.

[0055] Step 4: Machining: The part of the tube blank after radial forging is machined by turning, with a surface roughness Ra≤1.6, and finally a drum-shaped variable wall thickness titanium alloy tube with a middle section size of Φ100×δ5mm, a radial forging section size of Φ10×δ16mm, and a thick wall section size of Φ130×δ20mm is obtained.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for forming a drum-shaped variable wall thickness titanium alloy rotating tubular part, characterized in that: It includes the following steps: (1) Bar forging: Titanium alloy bars are selected as raw materials. After the bars are heated and kept warm in a box-type resistance furnace, the middle of the bars are forged and drawn out using a forging machine to prepare variable diameter billets. After forging, the bars are air-cooled. (2) Machining: Drilling and boring are performed on the variable diameter bar billet, and then the outer surface of the tube billet is turned to obtain a tube billet with constant inner diameter and variable wall thickness. (3) Pipe blank diameter forging: The end of the pipe blank with equal inner diameter and variable wall thickness is locally heated by induction heating, and then the heated part is diameter forged to obtain a pipe blank with variable diameter and variable wall thickness. After diameter forging, it is air cooled. (4) Machining: Machining is performed on the part of the tube blank after forging to obtain a drum-shaped variable wall thickness titanium alloy rotating tube.

2. The forming method of the drum-shaped variable wall thickness titanium alloy rotating tubular part according to claim 1, characterized in that: In step (1), the bar forging is carried out by heating the titanium alloy bar to 820℃~920℃ in a box-type resistance furnace and holding it for 60min~100min. Only the middle section of the bar is forged and drawn to obtain a variable diameter bar billet with large diameters at both ends and small diameter in the middle section. The bar billet is then air-cooled after forging.

3. The forming method of the drum-shaped variable wall thickness titanium alloy rotating tubular part according to claim 1, characterized in that: In step (2), the machining is to use a deep hole drilling machine to drill and bore the variable diameter bar blank to obtain a tube blank that meets the inner diameter requirements of the finished product; then, a centerless lathe is used to turn the outer surface of the tube blank, wherein the middle section of the tube blank is turned to the finished wall thickness size, and finally a tube blank with equal inner diameter and variable wall thickness with inner and outer surface roughness Ra≤1.6 is obtained.

4. The forming method of the drum-shaped variable wall thickness titanium alloy rotating tubular part according to claim 1, characterized in that: In step (3), the forging machine jaws send one end of the tube blank to the induction heating coil for online local heating. After heating to 820℃~920℃, the induction heating coil quickly withdraws from the forging line, and the tube blank is sent to the center of the forging machine hammer for end forging. The tube blank is forged to an outer diameter 2~4mm larger than the middle section of the tube blank. The other end of the tube blank is formed in the same way to obtain a tube blank with variable diameter and variable wall thickness. After forging, the tube blank is air-cooled.

5. The forming method of the drum-shaped variable wall thickness titanium alloy rotating tubular part according to claim 1, characterized in that: In step (4), the machining is performed by turning the part of the tube blank after diameter forging using a centerless lathe to obtain a drum-shaped variable wall thickness titanium alloy rotary tube with a surface roughness Ra≤1.6.

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