A Flexible Medium Cold Forming Method for a Large-Diameter Titanium Alloy Inner "U"-Shaped Inner Ring

Abstract

The present invention discloses a flexible medium cold forming method for a large-diameter titanium alloy inner "U"-shaped inner ring. Step 1: Design of the forming scheme; Step 2: Design of the processing flow; Step 3: Installation of the mold; Step 4: Forming and processing; Step 5: Three-coordinate measurement; Step 6: Turning processing. The present invention uses a semi-solid, flowable, rate-sensitive and highly viscous polymer, abbreviated as viscous medium, as the soft punch for forming, and forms a product that meets the dimensional requirements. The present invention has the advantages of low mold manufacturing cost, simple operation process, short processing cycle, and strong conversion ability to adapt to changes in product requirements, and can meet the requirements of high efficiency, high quality and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engine manufacturing, and particularly relates to a flexible medium cold forming method for a large-diameter titanium alloy inner "U"-shaped inner ring. Background Art

[0002] The stator inner ring of the booster stage of an aero-engine is made of TA1 titanium alloy sheet with a thickness of 1.0 mm. The part structure is as Figure 1 、 Figure 2 shown. Its cross-section is a "U" shape with the notch facing inward, the maximum diameter is 818 mm, and the diameters of the upper and lower ports are smaller than the diameter of the middle profile. Due to the large elastic modulus and high yield ratio of titanium alloy at room temperature, the conventional steel die cold forming method cannot be realized. Moreover, due to the part structure limitation, the usual integral ring forming die cannot be taken out. Therefore, the conventional forming process adopts the process of profile hot forming + welding + heat setting. The specific processing process flow is as follows: laser cutting of four-segment fan-shaped blanks - roll bending - graphite coating - hot forming of a 1 / 4 arc segment with a hot forming machine - washing - graphite removal - corrosion - wire cutting - welding of 4 1 / 4 arc segments into an integral ring - fine grinding of the weld seam - stress relaxation heat setting - turning. This process has a long processing cycle, high manufacturing cost, and the die has a low service life after repeated heating and cooling, and requires frequent die repair or replacement. Summary of the Invention

[0003] In order to solve the above technical problems, a flexible medium cold forming method for a large-diameter titanium alloy inner "U"-shaped inner ring is proposed. The specific technical solution is as follows:

[0004] A flexible medium cold forming method for a large-diameter titanium alloy inner "U"-shaped inner ring, the steps are as follows:

[0005] Step 1: Forming scheme design

[0006] Combined with the size and shape of the titanium alloy inner "U"-shaped inner ring, and according to the principle and characteristics of viscous medium forming, it is proposed to select a TA1 titanium alloy cone barrel;

[0007] Step 2: Processing flow design

[0008] Combined with the structure of the titanium alloy inner "U"-shaped inner ring, a processing process flow of viscous medium cold forming is proposed:

[0009] (1) Blank preparation

[0010] ① Use a laser cutting machine to process a 1 mm thick TA1 sheet into two fan-shaped blocks;

[0011] ② Use a roll bending machine to form the two fan-shaped blocks into two semi-cone barrels;

[0012] ③ Use an automatic argon arc welding machine to weld the two semi-cone barrels into a cone barrel;

[0013] ④ Grind the weld seam until it is flush with the substrate;

[0014] ⑤ Perform annealing treatment using a vacuum heat treatment furnace;

[0015] (2) Blank design

[0016] Combine the "U"-shaped inner ring structure in the titanium alloy to design the structure and dimensions of the blank for forming;

[0017] (3) Forming die design

[0018] Design a viscous medium forming die;

[0019] Step three: Install the die

[0020] (1) Install the medium cylinder on the lower platform of the four-column hydraulic press. The position of the medium cylinder body corresponds to the ejector rod, so that the ejector rod can move up and down along the cylinder body. The outer diameter of the ejector rod is precisely matched with the inner diameter of the cylinder body to play a role in sealing the viscous medium;

[0021] (2) Install the forming die on the lower platform of the four-column hydraulic press. The medium cylinder body is located in the inner holes of the lower backing plate and the spacer block, and ensure that the upper end face of the cylinder body is precisely fitted with the lower end face of the core die;

[0022] (3) Place the titanium alloy conical cylinder blank on the upper end face of the lower backing plate along the profile of the 4-die cavity;

[0023] (4) Place the core die with the installed sealing ring on the upper end face of the lower backing plate;

[0024] (5) Place the plug at the center of the lower end face of the upper backing plate and connect and fix it to the upper backing plate through 2 M18 bolts. The upper backing plate is placed above the die and connected and fixed to the core die through 6 M18 socket head cap screws.

[0025] Step four: Forming process

[0026] (1) Start the upper platform of the four-column hydraulic press. The main slider of the equipment provides a clamping force, and the clamping force is 820 tons;

[0027] (2) Start the ejector cylinder of the equipment to apply the viscous medium pressure. The viscous medium pressure is 90 MPa; when the viscous medium pressure reaches 90 MPa, unload the viscous medium pressure; at the same time, the main slider moves up and the core die is removed through the backing plate;

[0028] (3) Check the degree of the blank fitting the die with an R gauge. Take out the specimen when the minimum fillet radius of the specimen reaches R3; if the relevant dimensions are not reached, repeat the above actions and appropriately increase the viscous medium pressure;

[0029] Step five: Coordinate measuring machine measurement

[0030] Use a three - coordinate measuring machine to measure the dimensions of the stator inner ring.

[0031] Step Six: Turning

[0032] Use a lathe to machine the upper and lower stop mouths of the formed stator inner ring to the final dimensions.

[0033] In the preferred solution of the described flexible medium cold - forming method for a large - diameter titanium alloy inner "U" - shaped inner ring, in step two (3), the viscous medium forming die includes a plug, an upper backing plate, a core die, a female die, an outer sleeve, a lower backing plate, and a spacer block;

[0034] The spacer block is arranged at the lower end of the lower backing plate, and the inner - hole dimensions of the spacer block are the same as those of the lower backing plate, and they are symmetrically arranged up and down to form a cavity;

[0035] The outer sleeve is sleeved outside the female die and is arranged on the lower backing plate;

[0036] The upper platform of the four - column hydraulic press is pressed against the upper surface of the upper backing plate;

[0037] A concave platform is provided at the center of the core die, and the internal flow - channel structure communicates with the concave platform;

[0038] The core die is connected to the lower surface of the upper backing plate, and the concave platform is stuck at the center position of the upper backing plate;

[0039] The plug is installed in the groove reserved by the core die at the center position of the lower surface of the upper backing plate through screws, and the plug is matched with the flow channel of the core die;

[0040] Grooves are provided in the core die;

[0041] The grooves are sealed with YX - type cross - section sealing rings;

[0042] The medium cylinder is arranged in the cavity formed by the center of the spacer block and the lower backing plate,

[0043] The lower end face of the medium cylinder is jacked up by the ejector rod of the hydraulic press, so as to jack up the viscous medium in the medium cylinder. Through the sealing and tightening of the plug, the viscous medium in the medium cylinder is jacked into the flow channel of the core die, and then the pressure of the viscous medium is transmitted to the blank, realizing that the viscous medium expands the blank into the profile of the female die, thus realizing the forming of the titanium alloy inner "U" - shaped inner ring.

[0044] Advantages of the present invention:

[0045] Applying the present invention, the forming trial production of 4 pieces of the zero - stage stator inner rings of the booster stage has been completed. After forming, the height tolerance of the titanium alloy inner "U" - shaped inner ring is within 0.2 mm, the dimensional tolerances of the three main diameters are within 0.8 mm, and the fillet radius reaches R3, meeting the design requirements of the titanium alloy inner "U" - shaped inner ring.

[0046] Compared with the traditional hot forming process of titanium alloy, the present invention greatly shortens the processing time, reduces the processing cost, and improves the service life of the mold. Moreover, it has the advantages of simple operation process and strong conversion ability to adapt to product demand changes, and can meet the requirements of low cost and high quality for sheet metal parts with multiple varieties, small batches, and complex shapes, and has broad application prospects in aeroengines and gas turbines. Brief Description of the Drawings

[0047] Figure 1 It is a schematic structural diagram of the "U"-shaped inner ring inside the titanium alloy;

[0048] Figure 2 It is a schematic cross-sectional diagram of the "U"-shaped inner ring inside the titanium alloy;

[0049] Figure 3 It is a schematic diagram of the forming scheme;

[0050] Figure 4 It is a schematic structural diagram of the forming die;

[0051] Figure 5 It is a schematic diagram of the axial groove dimensions for the YX sealing ring;

[0052] Figure 6 It is a schematic structural diagram of the core die;

[0053] Figure 7 It is a schematic structural diagram of the medium cylinder.

[0054] In the figure: 1 - plug, 2 - upper backing plate, 3 - core die, 4 - female die, 5 - outer sleeve, 6 - lower backing plate, 7 - spacer block, 8 - cavity, 9 - groove. Detailed Description of the Specific Embodiment

[0055] The following further details the present invention in conjunction with the Figures 1-7 embodiments. Embodiment

[0056] A flexible medium cold forming method for a large-diameter "U"-shaped inner ring made of titanium alloy comprises the following steps:

[0057] Step 1: Forming scheme design

[0058] Combined with the dimensions and shape of the "U"-shaped inner ring inside the titanium alloy, and according to the forming principle and characteristics of the viscous medium, it is proposed to select the titanium alloy TA1 conical cylinder;

[0059] Step 2: Processing flow design

[0060] Combined with the structure of the "U"-shaped inner ring inside the titanium alloy, a processing technological process for viscous medium cold forming is proposed:

[0061] (1) Blank preparation

[0062] ① Use a laser cutting machine to process a 1-mm-thick TA1 sheet into two fan-shaped blocks;

[0063] ② Use a roll bending machine to form the two fan-shaped blocks into two semi-conical cylinders;

[0064] ③ Use an automatic argon arc welding machine to weld the two semi-conical cylinders into a conical cylinder;

[0065] ④ Grind the weld seam until it is flush with the base body;

[0066] ⑤ Use a vacuum heat treatment furnace for annealing treatment;

[0067] By using a viscous medium as a flexible punch, the wear of the die is reduced and the service life of the die is improved.

[0068] (2) Blank design

[0069] Combine the "U"-shaped inner ring structure in the titanium alloy to design the structure and dimensions of the blank for forming; the blank is welded by two TA1 plates into a conical cylinder as Figure 5 shown. The minimum diameter of the conical cylinder is Ф729 mm, the maximum diameter is Ф789 mm, and the thickness is 1.0 mm;

[0070] (3) Forming die design

[0071] Design a viscous medium forming die, as Figure 5 shown. The medium cylinder filled with the viscous medium material is placed in the cavity formed by the inner holes of the lower backing plate 6 and the spacer block 7. The blank is placed between the core die 3 and the die 4. The bottom surface of the small end of the blank is placed on the upper surface of the lower backing plate 6. The upper platform of the four-column hydraulic press presses the upper surface of the upper backing plate 2. By using the precise fit between the ejector rod of the four-column hydraulic press and the medium cylinder, the viscous medium in the medium cylinder is jacked up, and through the sealing and tightening action of the plug 1, the viscous medium in the medium cylinder is jacked into the runner of the core die 3, and then the pressure of the viscous medium is transmitted to the blank, realizing the bulging of the blank to the surface of the die 4 by using the viscous medium, so as to realize the forming of the "U"-shaped inner ring in the titanium alloy. Through the design of the runner structure of the core die 3, the amount of viscous medium required in the forming process is greatly reduced; and in the forming process, considering the sealing of the viscous medium, a groove for installing the sealing ring is set in the core die 3, as Figure 6 shown, and a YX-shaped cross-section sealing ring is used for sealing.

[0072] Step 3: Install the die

[0073] (1) Install the medium cylinder on the lower platform of the four-column hydraulic press. The position of the medium cylinder body corresponds to that of the ejector rod, so that the ejector rod can move up and down along the cylinder body. The outer diameter of the ejector rod is precisely matched with the inner diameter of the cylinder body to play a role in sealing the viscous medium;

[0074] (2) Install the forming die on the lower platform of the four-column hydraulic press. The medium cylinder body is located in the inner holes of the lower backing plate and the spacer block, and ensure that the upper end face of the cylinder body is precisely fitted with the lower end face of the core die.

[0075] (3) Place the titanium alloy conical cylinder blank along the profile of the 4-die on the upper end face of the lower backing plate.

[0076] (4) Place the core die with the installed sealing ring on the upper end face of the lower backing plate.

[0077] (5) Place the plug at the center of the lower end face of the upper backing plate and connect and fix it to the upper backing plate through 2 M18 bolts. The upper backing plate is placed above the die and connected and fixed to the core die through 6 M18 socket head cap screws.

[0078] Step Four: Forming Process

[0079] (1) Start the upper platform of the four-column hydraulic press. The main slider of the equipment provides the clamping force, and the clamping force is 820 tons.

[0080] (2) Start the ejector cylinder of the equipment to apply the viscous medium pressure. The viscous medium pressure is 90 MPa. After the viscous medium pressure reaches 90 MPa, unload the viscous medium pressure. At the same time, the main slider moves upward and the core die is taken out through the backing plate.

[0081] (3) Check the die sticking degree of the blank through the R gauge. Take out the specimen when the minimum fillet radius of the specimen reaches R3. If the relevant dimensions are not reached, repeat the above actions and appropriately increase the viscous medium pressure.

[0082] Step Five: Coordinate Measuring Machine Measurement

[0083] Use a coordinate measuring machine to measure the dimensions of the stator inner ring.

[0084] Step Six: Lathe Machining

[0085] Use a lathe to machine the upper and lower stop mouths of the formed stator inner ring to the final dimensions.

Claims

1. A cold forming method of a large-diameter titanium alloy inner "U"-shaped inner ring with flexible medium, Characterized in that: The steps are as follows: Step 1: Forming scheme design Combined with the size and shape of the titanium alloy inner "U"-shaped inner ring, and according to the forming principle and characteristics of the viscous medium, select the titanium alloy TA1 conical cylinder; Step 2: Processing flow design Combined with the structure of the titanium alloy inner "U"-shaped inner ring, a processing technological process of viscous medium cold forming is proposed: (1) Blank preparation ① Use a laser cutting machine to process a 1-mm-thick TA1 sheet into two fan-shaped blocks; ② Use a roll bending machine to form the two fan-shaped blocks into two semi-conical cylinders; ③ Use an automatic argon arc welding machine to weld the two semi-conical cylinders into a conical cylinder; ④ Grind the weld to be flush with the base body; ⑤ Use a vacuum heat treatment furnace for annealing treatment; (2) Blank design Combined with the structure of the titanium alloy inner "U"-shaped inner ring, design the structure and size of the blank for forming; (3) Forming die design Design a viscous medium forming die; The viscous medium forming die includes a plug, an upper backing plate, a core die, a die cavity, an outer sleeve, a lower backing plate and a spacer block; The spacer block is arranged at the lower end of the lower backing plate, and the inner hole size of the spacer block is the same as that of the lower backing plate, and they are arranged vertically and aligned to form a cavity; The outer sleeve is sleeved outside the die cavity and arranged on the lower backing plate; The upper platform of the four-column hydraulic press is pressed against the upper surface of the upper backing plate; A concave platform is provided in the center of the core die, and the internal flow channel structure communicates with the concave platform; The core die is connected to the lower surface of the upper backing plate, and the concave platform is stuck at the central position of the upper backing plate; The plug is installed in the groove reserved by the core die at the central position of the lower surface of the upper backing plate through screws, and the plug cooperates with the flow channel of the core die; A groove is provided in the core die; The groove is sealed with a YX-shaped cross-section sealing ring; The medium cylinder is arranged in the cavity. By jacking up the viscous medium in the medium cylinder, through the sealing and jacking of the plug, the viscous medium in the medium cylinder is jacked into the flow channel of the core die, and then the pressure of the viscous medium is transmitted to the blank, so that the viscous medium deforms the blank into the mold surface of the die cavity, thereby realizing the forming of the titanium alloy inner "U"-shaped inner ring; Step 3: Install the die Install the medium cylinder on the lower platform of the four-column hydraulic press. The position of the medium cylinder body corresponds to the position of the ejector rod, so that the ejector rod can move up and down along the cylinder body. The outer diameter of the ejector rod is precisely matched with the inner diameter of the cylinder body to play a role in sealing the viscous medium; Place the viscous medium into the medium cylinder and fill it up; (3) Install the forming die on the lower platform of the four-column hydraulic press. The medium cylinder body is located in the inner holes of the lower backing plate and the spacer block, and ensure that the upper end face of the cylinder body is precisely fitted with the lower end face of the core die; (4) Place the titanium alloy conical cylinder along the mold surface of the die cavity on the upper end face of the lower backing plate; (5) Place the core die with the installed sealing ring on the upper end face of the lower backing plate; (6) Place the plug at the center of the lower end face of the upper backing plate and connect and fix it to the upper backing plate through 2 M18 bolts. The upper backing plate is placed above the die and connected and fixed to the core die through 6 M18 socket head cap screws; Step 4: Forming processing (1) Start the upper platform of the four-column hydraulic press. The main slider of the equipment provides a clamping force, and the clamping force is 820 tons; (2)Start the ejector cylinder of the device to apply the pressure of the viscous medium, and the pressure of the viscous medium is 90 MPa; after the pressure of the viscous medium reaches 90 MPa, unload the pressure of the viscous medium; at the same time, the main slider moves upward and the core die is taken out through the backing plate; (3)Check the degree of the blank adhering to the die by using an R gauge, and take out the blank after the minimum fillet radius of the blank reaches R3; Step Five: Coordinate Measuring Use a coordinate measuring machine to measure the dimensions of the inner "U"-shaped inner ring of the titanium alloy; Step Six: Turning Use a lathe to machine the upper and lower stops of the formed inner "U"-shaped inner ring of the titanium alloy to the final dimensions.

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