A method for electric current assisted local shape correction of linear friction welded joint of blisk

Abstract

A linear friction welding joint current auxiliary local shape correction method of blisk, steps are as follows: preparing shape correction equipment; measuring blisk to determine size out-of-tolerance blade; machining necking transition section at weld; sending blisk into vacuum environment device; sequentially installing single shape correction tooling and electrode at weld, electrode is connected to direct current pulse power supply; connecting cooling device; sequentially starting vacuum environment device, cooling device, direct current pulse power supply and single shape correction tooling; correcting and preserving; after shape correction stress is reduced to set value, direct current pulse power supply is turned off; cooling to normal temperature; recovering normal pressure environment, cooling device is turned off, electrode and single shape correction tooling are sequentially removed. The present application utilizes Joule heat effect and electroplastic effect generated by current through metal to realize local heating of welding joint, has directional correction ability to any specific out-of-tolerance blade, and improves shape correction efficiency; necking transition section is used to improve current density, shape correction temperature field is more concentrated, and high-precision shape correction is realized by spot cooling.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine component manufacturing technology, and in particular relates to a current-assisted local shaping method for linear friction welding joints of integral bladed disks. Background Technology

[0002] Linear friction welding (LFD) is a welding method that utilizes metal friction and deformation heat to achieve a good metallurgical bond between metals under vertical compressive stress. Because LFD is a solid-state welding process, it avoids the adverse effects of coarse weld joint microstructure and reduced mechanical properties compared to the base material. Furthermore, the weld interface undergoes significant plastic deformation, resulting in a typically fine and uniform microstructure, and the mechanical properties of the weld joint are comparable to those of the base material. Due to these advantages, LFD has become one of the key technologies for manufacturing integral bladed disks for aero-engine fans.

[0003] Because the manufacturing precision of integral bladed disks directly affects key indicators such as the aerodynamic performance of aero engines, the requirements for manufacturing precision are usually very stringent. However, when using linear friction welding technology to process integral bladed disks, the welding precision is not only affected by the precision of hardware such as welding equipment and clamping fixtures, but also directly related to process parameters and material deformation behavior.

[0004] For example, under high welding pressure and shrinkage, high residual stress can easily occur at the weld joint, leading to reduced control precision of the welding equipment and tooling, and ultimately a significant decrease in the overall bladed disk's welding precision. Therefore, for integral bladed disk parts that do not meet the welding precision requirements, overall heat treatment and reshaping methods are typically used to improve and optimize the precision of the integral bladed disk parts.

[0005] However, the overall heat treatment straightening method is limited by the heat treatment temperature of the base material, resulting in a typically low straightening temperature and thus a very limited overall straightening effect. Furthermore, overall hot straightening requires complex tooling, and the assembly and disassembly of this tooling is time-consuming and labor-intensive, leading to low efficiency. Moreover, the tooling assembly and disassembly process can easily scratch the blade surface, compromising the surface integrity of the integral bladed disk component. Additionally, it lacks the ability to orient and correct specific out-of-tolerance blades.

[0006] In addition, during the overall heat treatment and straightening process, the overall heat straightening fixture needs to be in contact with the overall bladed disk at high temperatures for a long time, which can easily lead to diffusion reactions of elements between the overall bladed disk and the fixture, thereby affecting the service performance of the overall bladed disk. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a current-assisted local correction method for linear friction welding joints of integral bladed disks. Utilizing the Joule heating effect and electroplastic effect generated by current passing through the metal, the welding joint temperature is rapidly increased, overcoming the limitation of correction temperature caused by the heat treatment temperature of the blade and disk base material. This method enables directional correction of any specific out-of-tolerance blade, significantly improving correction efficiency. By processing a necking transition section at the weld seam of the welding joint to increase the current density at the welding joint, the correction temperature field becomes more concentrated. Cooling the electrodes and individual correction fixtures prevents localized high temperatures from affecting the performance of the blade and disk components, achieving high-precision correction of any specific out-of-tolerance blade.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a current-assisted local shaping method for linear friction welding joints of integral bladed disks, comprising the following steps:

[0009] Step 1: Prepare the equipment for local alignment of the welded joint. The equipment includes a vacuum environment device, a DC pulse power supply, electrodes, a temperature measuring device, individual alignment fixtures, and a cooling device.

[0010] Step 2: Measure the dimensional parameters of the entire bladed disk to identify individual blades with dimensional deviations;

[0011] Step 3: A necked transition section is machined at the weld joint between the disk and the out-of-tolerance blade using machining methods.

[0012] Step 4: After the necking transition section is processed, the integral bladed disk is sent into the vacuum environment device. An insulating and heat-insulating platform is pre-set in the vacuum environment device. The integral bladed disk needs to be fixedly installed on the insulating and heat-insulating platform.

[0013] Step 5: Install individual alignment fixtures on the blade end and disk end of the weld at the weld joint, respectively. Stress sensors are pre-installed in the individual alignment fixtures.

[0014] Step 6: Install electrodes on the single-unit straightening fixture, and connect the electrodes on both sides of the weld at the welding joint to the positive and negative terminals of the DC pulse power supply respectively through wires;

[0015] Step 7: Connect the cooling device to the electrode and the single-unit shaping fixture;

[0016] Step 8: Activate the vacuum environment device to place the entire impeller disk in a vacuum environment;

[0017] Step 9: Activate the cooling device to cool the electrodes and the monomer alignment fixture.

[0018] Step 10: Turn on the DC pulse power supply to allow the pulse current to flow through the welding joint area, and use a temperature measuring device to monitor the temperature of the welding joint area in real time.

[0019] Step 11: When the temperature at the welded joint reaches the set value, start the individual unit straightening fixture. The fixture corrects the dimensional deviation of the individual blades. After correction, keep it warm for a set time. During the correction and heat preservation process, the stress sensor detects the straightening stress in real time.

[0020] Step 12: After the stress is reduced to the set value, gradually reduce the pulse current value until the pulse current value returns to zero, and then turn off the DC pulse power supply.

[0021] Step 13: After the temperature at the welded joint drops to the set value, the vacuum environment is restored to normal pressure, the cooling device is turned off, and the electrodes and single-unit calibration fixtures are removed in sequence. The dimensional deviation correction of the single-unit blades is completed.

[0022] When the number of individual blades with out-of-tolerance dimensions on the overall bladed disk exceeds two, after the first individual blade has completed the dimensional out-of-tolerance correction, there is no need to remove the overall bladed disk from the vacuum environment device. Simply repeat steps five to thirteen until the dimensional out-of-tolerance correction of the remaining individual blades is completed.

[0023] The dimensions of the necking transition section are determined based on the electrothermal relationship and thermal conductivity of the individual blades and the base material of the integral bladed disk.

[0024] The cooling device is connected to the electrode and the single-unit straightening fixture in an embedded or bonded manner, and the cooling medium of the cooling device is a water-cooled medium or an air-cooled medium.

[0025] The temperature measuring device is a contact thermocouple or a non-contact infrared thermometer. When the temperature measuring device is a contact thermocouple, it needs to be installed separately at the welding joint after the individual calibration fixture is installed.

[0026] The base materials of the individual blades and the disk are homogeneous alloys or dissimilar alloys. During local shaping, the temperature range for correction and heat preservation is 600℃~1200℃, and the time range for correction and heat preservation is 15min~300min.

[0027] The beneficial effects of this invention are:

[0028] The integral bladed disk linear friction welding joint current-assisted local correction method of the present invention utilizes the Joule heating effect and electroplastic effect generated by the current passing through the metal to achieve a rapid increase in the temperature of the welding joint, breaking through the limitation of the correction temperature by the heat treatment temperature of the blade and disk base material, and has the ability to perform directional correction of any specific out-of-tolerance blade, greatly improving the correction efficiency; by processing a necking transition section at the weld seam of the welding joint to increase the current density at the welding joint, the correction temperature field is more concentrated, and by cooling the electrodes and individual correction tooling, the high temperature of local correction is avoided from affecting the performance of the blade and disk parts, realizing high-precision correction of any specific out-of-tolerance blade. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the integral bladed disk structure;

[0030] Figure 2 This is a schematic diagram of current-assisted local alignment of an integral bladed disk at the welded joint.

[0031] In the figure, 1—DC pulse power supply, 2—electrode, 3—single unit alignment tool, 4—single unit blade, 5—disc body, 6—necked transition section, 7—weld at the welding joint. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0033] A current-assisted local shaping method for linear friction welding joints of integral bladed disks includes the following steps:

[0034] Step 1: Prepare the equipment for local alignment of the welded joint. The equipment includes a vacuum environment device, a DC pulse power supply 1, an electrode 2, a temperature measuring device, a single-unit alignment fixture 3, and a cooling device.

[0035] Step Two: [Regarding...] Figure 1 The overall bladed disk shown was dimensionally measured to identify individual blades 4 with dimensional deviations. In this embodiment, a coordinate measuring machine was used as the measuring tool.

[0036] Step 3: A necked transition section 6 is machined at the weld joint 7 of the disk body 5 and the dimensionally out-of-tolerance blade 4. The size of the necked transition section 6 is determined based on the electrothermal relationship and thermal conductivity of the base material of the blade 4 and the disk body 5. In this embodiment, the necked transition section 6 is machined by milling. The necked transition section 6 forms a small-diameter cross-section structure relative to the weld joint. The groove cross-section of the necked transition section 6 is an arc surface. Since the cross-sectional area of ​​the weld where the necked transition section 6 is located is smaller, the current density at the small cross-section can be effectively increased, thereby causing the temperature to rise rapidly.

[0037] Step 4: The integral bladed disk after the necking transition section 6 has been processed is sent into the vacuum environment device. An insulating and heat-insulating platform is pre-set in the vacuum environment device. The integral bladed disk needs to be fixedly installed on the insulating and heat-insulating platform. In this embodiment, the integral bladed disk can be mechanically fixed on the insulating and heat-insulating platform using a general-purpose tooling fixture. There is no need to design and manufacture new tooling fixtures separately.

[0038] Step 5: Install individual alignment fixture 3 on the blade end and disk end of weld 7 at the weld joint. Stress sensors are pre-installed in the individual alignment fixture 3.

[0039] Step Six: Install electrodes 2 on the single-unit straightening fixture 3, and connect electrodes 2 on both sides of the weld 7 at the welding joint to the positive and negative terminals of the DC pulse power supply 1 respectively via wires. Figure 2 As shown; in this embodiment, electrode 2 is a low-resistivity copper electrode;

[0040] Step 7: Connect the cooling device to electrode 2 and single-unit shaping fixture 3. The cooling device can be embedded or attached to electrode 2 and single-unit shaping fixture 3. The cooling medium of the cooling device is water cooling medium or air cooling medium.

[0041] Step 8: Activate the vacuum environment device to place the entire bladed disk under vacuum. In this embodiment, when the base material of the individual blade 4 and the disk body 5 is the same titanium alloy, the vacuum degree is controlled to be no greater than 1×10⁻⁶. -2 When the base material of the single blade 4 and the disk 5 is TC4 / TC17 dissimilar titanium alloy, the vacuum degree is controlled to be no greater than 5×10. -3 pa;

[0042] Step 9: Activate the cooling device to cool the electrode 2 and the single-unit straightening fixture 3. In this embodiment, by cooling the electrode 2 and the single-unit straightening fixture 3, the temperature of the welding joint can be prevented from being conducted to the main body of the blade 4 and the disk 5, and the local high temperature during straightening can be prevented from affecting the performance of the blade and the disk. Specifically, this is used to ensure that the temperature of the electrode 2 and the single-unit straightening fixture 3 does not exceed 100°C.

[0043] Step 10: Start the DC pulse power supply 1 to allow the pulse current to flow through the welding joint. The temperature of the welding joint is monitored in real time by a temperature measuring device, which can be a contact thermocouple or a non-contact infrared thermometer. When a contact thermocouple is used, it needs to be installed separately on the welding joint after the individual calibration fixture 3 is installed. In this embodiment, the pulse current of the DC pulse power supply 1 can be adjusted within the range of 0 to 30000A.

[0044] Step 11: Once the temperature at the welded joint reaches the set value, activate the individual unit straightening fixture 3. Use the fixture 3 to correct any dimensional deviations in the individual blade 4. After correction, maintain the temperature for a set time. During this process, a stress sensor monitors the straightening stress in real time. If the base materials of the individual blade 4 and the disk 5 are homogeneous or dissimilar alloys, the temperature range for local straightening is 600℃~1200℃, and the holding time is 15min~300min. In this embodiment, when the base materials of the individual blade 4 and the disk 5 are homogeneous titanium alloys, the temperature for straightening is controlled at 600℃~1100℃, and the holding time is controlled at 15min~120min. When the base materials of the individual blade 4 and the disk 5 are TC4 / TC17 dissimilar titanium alloys, the temperature for straightening is controlled at 800℃~900℃, and the holding time is controlled at 30min~120min.

[0045] Step 12: After the forming stress decreases to the set value, gradually reduce the pulse current value until the pulse current value returns to zero, and then turn off the DC pulse power supply 1; In this embodiment, when the base material of the single blade 4 and the disk 5 is the same titanium alloy, the pulse current value is reduced after the forming stress decreases to 10MPa; when the base material of the single blade 4 and the disk 5 is TC4 / TC17 dissimilar titanium alloy, the pulse current value is reduced after the forming stress decreases to 5MPa;

[0046] Step 13: When the temperature at the welded joint drops to the set value of 100℃, the vacuum environment device is restored to normal pressure, the cooling device is turned off, and electrode 2 and single-unit straightening fixture 3 are removed in sequence. The dimensional deviation correction of single-unit blade 4 is completed. When the number of single-unit blades 4 with dimensional deviation on the whole bladed disk exceeds two, after the first single-unit blade 4 completes the dimensional deviation correction, it is not necessary to remove the whole bladed disk from the vacuum environment device. Just repeat steps five to thirteen until the dimensional deviation correction of the remaining single-unit blades 4 is completed.

[0047] The solutions described in the embodiments are not intended to limit the scope of patent protection of this invention. All equivalent implementations or modifications that do not depart from the scope of this invention are included in the patent scope of this case.

Claims

1. A current-assisted local shaping method for linear friction welding joints of integral bladed disks, characterized in that... Includes the following steps: Step 1: Prepare the equipment for local alignment of the welded joint. The equipment includes a vacuum environment device, a DC pulse power supply, electrodes, a temperature measuring device, individual alignment fixtures, and a cooling device. Step 2: Measure the dimensional parameters of the entire bladed disk to identify individual blades with dimensional deviations; Step 3: A necked transition section is machined at the weld joint between the disk and the out-of-tolerance blade using machining methods. Step 4: After the necking transition section is processed, the integral bladed disk is sent into the vacuum environment device. An insulating and heat-insulating platform is pre-set in the vacuum environment device. The integral bladed disk needs to be fixedly installed on the insulating and heat-insulating platform. Step 5: Install individual alignment fixtures on the blade end and disk end of the weld at the weld joint, respectively. Stress sensors are pre-installed in the individual alignment fixtures. Step 6: Install electrodes on the single-unit straightening fixture, and connect the electrodes on both sides of the weld at the welding joint to the positive and negative terminals of the DC pulse power supply respectively through wires; Step 7: Connect the cooling device to the electrode and the single-unit shaping fixture; Step 8: Activate the vacuum environment device to place the entire impeller disk in a vacuum environment; Step 9: Activate the cooling device to cool the electrodes and the monomer alignment fixture. Step 10: Turn on the DC pulse power supply to allow the pulse current to flow through the welding joint area, and use a temperature measuring device to monitor the temperature of the welding joint area in real time. Step 11: When the temperature at the welded joint reaches the set value, start the individual unit straightening fixture. The fixture corrects the dimensional deviation of the individual blades. After correction, keep it warm for a set time. During the correction and heat preservation process, the stress sensor detects the straightening stress in real time. Step 12: After the stress is reduced to the set value, gradually reduce the pulse current value until the pulse current value returns to zero, and then turn off the DC pulse power supply. Step 13: After the temperature at the welded joint drops to the set value, the vacuum environment device is restored to normal pressure, the cooling device is turned off, and the electrodes and single-unit calibration fixtures are removed in sequence. The dimensional deviation correction of the single-unit blades is completed.

2. The method for current-assisted local shaping of a linear friction welded joint of an integral bladed disk according to claim 1, characterized in that: When the number of individual blades with out-of-tolerance dimensions on the overall bladed disk exceeds two, after the first individual blade has completed the dimensional out-of-tolerance correction, there is no need to remove the overall bladed disk from the vacuum environment device. Simply repeat steps five to thirteen until the dimensional out-of-tolerance correction of the remaining individual blades is completed.

3. The method for current-assisted local shaping of a linear friction welded joint of an integral bladed disk according to claim 1, characterized in that: The dimensions of the necking transition section are determined based on the electrothermal relationship and thermal conductivity of the individual blades and the base material of the integral bladed disk.

4. The method for current-assisted local shaping of a linear friction welded joint of an integral bladed disk according to claim 1, characterized in that: The cooling device is connected to the electrode and the single-unit straightening fixture in an embedded or bonded manner, and the cooling medium of the cooling device is a water-cooled medium or an air-cooled medium.

5. The method for current-assisted local shaping of a linear friction welded joint of an integral bladed disk according to claim 1, characterized in that: The temperature measuring device is a contact thermocouple or a non-contact infrared thermometer. When the temperature measuring device is a contact thermocouple, it needs to be installed separately at the welding joint after the individual calibration fixture is installed.

6. The method for current-assisted local shaping of a linear friction welded joint of an integral bladed disk according to claim 1, characterized in that: The base materials of the individual blades and the disk are homogeneous alloys or dissimilar alloys. During local shaping, the temperature range for correction and heat preservation is 600℃~1200℃, and the time range for correction and heat preservation is 15min~300min.

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