A method of welding a drive shaft with controlled initial imbalance

Abstract

This invention belongs to the field of aero-engine technology and provides a method for processing a welded transmission rod to control initial imbalance. The welded transmission rod includes a first transmission rod and a second transmission rod. The method includes: providing a positioning stop at the welding end of the first or second transmission rod; connecting the positioning stop to form a transmission rod to be welded; inserting a mandrel into the transmission rod to be welded and axially fixing it with bolts to form a welding assembly; performing vacuum treatment in a vacuum environment; welding and fixing the positioning stop using vacuum electron beam welding; removing the positioning stop and taking out the mandrel after welding; machining the initial spline and performing cyanidation heat treatment; sequentially performing outer diameter finishing, spline outer diameter grinding, and spline inner diameter finishing on the cyanidation heat-treated transmission rod to obtain the final transmission rod. The method of this invention can minimize the deformation effects caused by welding and cyanidation heat treatment of the welded transmission rod, and obtain a lower initial imbalance.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine technology and relates to a method for processing a welded transmission rod to control the initial imbalance. Background Technology

[0002] In aero-engines, transmission rods are characterized by their slender length and high rotational speed. To improve their vibration margin, the central transmission rod is often thickened. Under the condition that the spline parameters at both ends remain unchanged, a large diameter surface, an upper variable cross section, and a lower variable cross section are formed. To achieve the desired structure, the central transmission rod is usually designed with two ends, which are then connected by welding.

[0003] The transmission rod requires two important hot working processes during manufacturing, both of which cause deformation. Currently, structural imbalance is often controlled by hot straightening or by not controlling deformation and simply removing material from both ends of the transmission rod. However, for thin-walled long transmission rods, due to their poor stiffness, it is difficult to achieve high-precision imbalance control. Summary of the Invention

[0004] To address the technical problem of difficulty in controlling the imbalance caused by the poor stiffness of thin-walled long transmission rods, this invention discloses a method for manufacturing a welded transmission rod to control the initial imbalance. The welded transmission rod includes a first transmission rod and a second transmission rod. The method includes the following steps:

[0005] S1. Both the spline end of the first transmission rod and the second transmission rod have machining allowance at their inner holes, and a positioning stop is provided at the welding end of the first transmission rod or the second transmission rod. S2. The first transmission rod and the second transmission rod are connected through the positioning stop to form a transmission rod to be welded. The mandrel is inserted into the transmission rod to be welded and axially fixed by bolt assembly to form a component to be welded. The mandrel is provided with an exhaust channel near the positioning stop that communicates with the outside. S3. Place the component to be welded in a vacuum environment for vacuum treatment, and weld and fix the positioning stop by vacuum electron beam welding. After welding, remove the positioning stop and take out the mandrel to obtain the transmission rod welded part. S4. Initial splines are machined at both ends of the transmission rod welded part, and the tooth surfaces of the initial splines are subjected to cyanide heat treatment. S5. The transmission rod after cyanide heat treatment is sequentially machined for outer diameter finishing, spline outer diameter grinding, and spline inner diameter finishing to obtain the final transmission rod.

[0006] Furthermore, the splined ends of the first and second transmission rods have small-diameter inner holes, while the welded ends have large-diameter inner holes.

[0007] Furthermore, the length of the mandrel is greater than the length of the welded transmission rod, and the end of the mandrel near the positioning stop is provided with a shoulder, while the end away from the positioning stop is provided with an external thread for mounting the bolt assembly.

[0008] Furthermore, the first transmission rod and the second transmission rod have different lengths.

[0009] Furthermore, a rough machining reference surface is provided at the end of the transmission rod welded part and near the positioning stop, and splines are machined at both ends of the transmission rod welded part according to the rough machining reference surface.

[0010] Furthermore, before performing cyanidation heat treatment on the spline tooth surface, sealing components are installed at both ends of the inner hole of the transmission rod welded part to prevent the inner hole of the transmission rod from being cyanided and to protect it. After the cyanidation heat treatment, the transmission rod is hoisted to release thermal stress.

[0011] Further, in step S5, the transmission rod after cyanide heat treatment is sequentially subjected to outer diameter finishing, spline outer diameter grinding, and spline inner diameter finishing, including: S51. Based on the design dimensions of the outer diameter of the transmission rod, the outer diameter of the transmission rod after cyanide heat treatment is precision machined. S52. Based on thermal deformation analysis, at the welding ends of the first transmission rod and the second transmission rod, and near the change in diameter between the inner hole of the spline end and the inner hole of the welding end, select a position with the smallest thermal deformation as the joint reference surface for finishing. S53. Based on the joint reference plane, grind the spline and finish the outer diameter of the transmission rod. Using the ground spline outer circle as a reference, finish the spline inner hole according to the design dimensions of the spline inner hole. After the spline inner hole is finished, perform dynamic balancing and material removal treatment.

[0012] The processing method of the present invention can minimize the deformation caused by hot processing such as welding and cyaniding of welded transmission rods, and obtain a lower initial imbalance. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a flowchart of a method for processing a welded transmission rod to control the initial imbalance, as disclosed in an embodiment of the present invention. Figure 2 This is a schematic diagram of a welded transmission rod disclosed in an embodiment of the present invention; Figure 3 This is a schematic diagram of the component to be welded according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the transmission rod hoisting and thermal stress release disclosed in an embodiment of the present invention; Among them, 1. First transmission rod; 2. Second transmission rod; 3. First spline; 4. Second spline; 6. First variable cross section; 7. Second variable cross section; 8. First material removal position; 9. Second material removal position; 10. Positioning stop; 12. Mandrel; 13. Bolt assembly; 14. Shoulder; 15. Exhaust channel; 16. First sealing element; 17. Second sealing element; 18. Counterweight; 19. Rope. Detailed Implementation

[0015] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0016] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features of the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] This invention discloses a method for machining a welded transmission rod to control the initial imbalance. See [link to relevant documentation]. Figure 2 As shown, the welded transmission rod includes a first transmission rod 1 and a second transmission rod 2. In implementation, the first transmission rod 1 can also be referred to as the upper transmission rod, and the second transmission rod 2 can also be referred to as the lower transmission rod. The splined ends of the first transmission rod 1 and the second transmission rod 2 have small-diameter inner holes, while the welded ends have large-diameter inner holes. The final transmission rod can be obtained by assembling, welding, and machining the first transmission rod 1 and the second transmission rod 2. The first transmission rod 1 and the second transmission rod 2 have different lengths; for example, the first transmission rod 1 can be set as a long transmission rod, and the second transmission rod 2 can be set as a short transmission rod.

[0018] See Figure 1 As shown, the machining method for welded transmission rods includes the following steps: S1. Both the spline end of the first transmission rod 1 and the second transmission rod 2 have machining allowances, and a positioning stop 10 is provided at the welding end of the first transmission rod 1 or the second transmission rod 2. S2. The first transmission rod 1 and the second transmission rod 2 are connected through the positioning stop 10 to form a transmission rod to be welded. The mandrel 12 is inserted into the transmission rod to be welded and axially fixed by bolt assembly to form a component to be welded. The mandrel 12 is provided with an exhaust channel 15 near the positioning stop 10 that communicates with the outside. S3. Place the component to be welded in a vacuum environment for vacuum treatment, and weld and fix the positioning stop 10 by vacuum electron beam welding. After welding, remove the positioning stop 10 and take out the mandrel 12 to obtain the transmission rod welded part. S4. Initial splines are machined at both ends of the transmission rod welded part, and the tooth surfaces of the initial splines are subjected to cyanide heat treatment. S5. The transmission rod after cyanide heat treatment is sequentially machined for outer diameter finishing, spline outer diameter grinding, and spline inner diameter finishing to obtain the final transmission rod.

[0019] Furthermore, in the implementation of step S1 above, a machining allowance is provided at the inner hole of the spline end, see [reference]. Figure 2 As shown, machining allowances can be left at the inner hole ΦM position of the first spline 3 and the inner hole ΦN position of the second spline 4, so that after all hot working is completed, the wall thickness at the spline can be ensured by grinding the allowance to compensate for the deformation of the spline caused by hot working.

[0020] Simultaneously, before welding, a positioning stop 10 is provided at the welding end of the first transmission rod 1 or the second transmission rod 2, see [reference]. Figure 3 As shown, a short transmission rod, such as the second transmission rod 2, is provided with a positioning stop 10. By adjusting the fit tolerance of the stop position to an interference fit and using heat fitting for assembly, it is ensured that the two parts remain concentric during welding.

[0021] Furthermore, in step S2, to ensure that the first transmission rod 1 and the second transmission rod 2 remain concentric during welding, a mandrel 12 is inserted into its center for axial positioning. The length of the mandrel 12 is greater than the length of the welded transmission rod. A shoulder 14 is provided at one end of the mandrel 12 near the positioning stop, and an external thread for mounting the bolt assembly 13 is provided at the other end. The diameter of the venting channel 15 on the mandrel 12 is required to be no less than ø2. The venting channel 15 allows the welding position inside the assembly to be welded to communicate with the outside, ensuring the same internal and external pressure difference.

[0022] Furthermore, in implementation, the mandrel 12 employs a small clearance fit at the inner hole ΦM position of the first spline 3 and the inner hole ΦN of the second spline 4 to improve the axial support of the mandrel 12. See also Figure 3As shown, after the mandrel 12 is installed into the transmission rod to be welded, it is tightened axially and circumferentially braked by the bolt assembly 13 to reduce the deformation caused by the movement of the upper and lower transmission rods during welding.

[0023] Furthermore, in step S3 above, a vacuum is first drawn in a vacuum environment before welding to completely evacuate the shaft of the transmission rod before welding. After welding is completed, the mandrel 12 can be removed to obtain the welded transmission rod part for subsequent processing.

[0024] Furthermore, when implementing step S4 above, see [reference needed]. Figure 2 As shown, a rough machining reference surface A can be set at the end of the transmission rod welded part and near the positioning stop 10. This rough machining reference surface A can be a position on the first transmission rod 1 where the heat-affected zone is relatively small. Splines are machined at both ends of the transmission rod welded part according to the rough machining reference surface, and then the machined splines are subjected to cyanide heat treatment. In implementation, the distance between the rough machining reference surface A and the weld can be designed to be greater than or equal to 15mm. During machining, a small machining allowance of 0.5~1.5mm should be left on the outer diameter of the spline. After all hot working is completed, the deformation of the outer diameter of the spline is corrected.

[0025] Before performing cyanidation heat treatment, to prevent the inside of the transmission rod from being cyanided, see [reference needed]. Figure 4 As shown, a first sealing element 16 can be provided at the splined end of the first transmission rod 1, and a second sealing element 17 can be provided at the splined end of the second transmission rod 2. The first sealing element 16 and the second sealing element 17 can be welded blocks and welded into the hole. After cyanidation heat treatment, a rope 19 can be used for hoisting, and a counterweight 18 weighing no less than 1 kg can be provided at the lower end of the second transmission rod 2 to hoist the transmission rod and release thermal stress.

[0026] Furthermore, the transmission rod after cyanide heat treatment is sequentially subjected to outer diameter finishing, spline outer diameter grinding, and spline inner diameter finishing, including: S51. Based on the design dimensions of the outer diameter of the transmission rod, the outer diameter of the transmission rod after cyanide heat treatment is precision machined. S52. Based on thermal deformation analysis, at the welding ends of the first transmission rod 1 and the second transmission rod 2, and near the change in diameter between the inner hole of the spline end and the inner hole of the welding end, select a position with the smallest thermal deformation as the joint reference surface for finishing. S53. Based on the aforementioned joint reference plane, grind the spline and finish the outer diameter of the transmission rod. Using the ground spline outer circle as a reference, finish the spline inner hole according to the designed dimensions. After finishing the spline inner hole, perform dynamic balancing and material removal. Finishing the spline inner hole can ensure uniform wall thickness at the spline. Figure 4As shown, the first transmission rod 1 is provided with a first material removal position 8, and the second transmission rod 2 is provided with a second material removal position 9.

[0027] For specific implementation of step S5 above, please refer to [reference needed]. Figure 2 As shown, the finishing reference surface B and finishing reference surface C, which have less impact from thermal deformation, can be selected as the machining reference to complete the finishing of the entire roughing reference surface A. All outer diameter surface dimensions can be machined using the roughing reference surface A as the reference. Finally, the inner hole dimensions can be machined using the outer diameter of the first spline 3 and the second spline 4 tooth surfaces as the reference.

[0028] When selecting finishing datum surface B and finishing datum surface C, please refer to... Figure 2 As shown, the finishing reference surface B can be located near the first variable cross-section 6 of the first transmission rod 1, and the distance between the two can be set to 10~20mm. The finishing reference surface C can be located near the second variable cross-section 7 of the second transmission rod 2, and the distance between the two can be set to 10~20mm.

[0029] The processing method of the present invention can minimize the deformation caused by hot processing such as welding and cyaniding of welded transmission rods, and obtain a lower initial imbalance.

[0030] Obviously, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for processing a welded transmission rod to control initial imbalance, the welded transmission rod comprising a first transmission rod (1) and a second transmission rod (2), wherein the splined ends of the first transmission rod (1) and the second transmission rod (2) are small-diameter inner holes, and the welded ends are large-diameter inner holes, characterized in that, The method includes: Both the spline end of the first transmission rod (1) and the second transmission rod (2) have machining allowances, and a positioning stop (10) is provided at the welding end of the first transmission rod (1) or the second transmission rod (2). The first transmission rod (1) and the second transmission rod (2) are connected through the positioning stop (10) to form a transmission rod to be welded. The mandrel (12) is inserted into the transmission rod to be welded and axially fixed by the bolt assembly to form a component to be welded. The mandrel (12) is provided with an exhaust channel (15) near the positioning stop (10) that communicates with the outside. The component to be welded is placed in a vacuum environment for vacuum treatment, and the positioning stop (10) is welded and fixed by vacuum electron beam welding. After welding, the positioning stop (10) is removed and the mandrel (12) is taken out to obtain the transmission rod welded part. Initial splines are machined at both ends of the transmission rod welded part, and the tooth surfaces of the initial splines are subjected to cyanidation heat treatment. Before the cyanidation heat treatment of the spline tooth surfaces, sealing parts are installed at the inner holes at both ends of the transmission rod welded part. After the cyanidation heat treatment, the transmission rod is hoisted to release thermal stress. The transmission rod after cyanide heat treatment is sequentially machined in the following ways: the outer diameter is finished, the spline outer diameter is ground, and the spline inner diameter is finished. This includes: the outer diameter of the transmission rod after cyanide heat treatment is finished according to the design dimensions of the transmission rod outer diameter; based on thermal deformation analysis, a position with the smallest thermal deformation is selected at the welding end of the first transmission rod (1) and the second transmission rod (2), and near the diameter change position between the inner hole of the spline end and the inner hole of the welding end, respectively, as the joint reference surface for finishing; based on the joint reference surface, the spline is ground and the outer diameter of the transmission rod is finished; the inner hole of the spline is finished according to the design dimensions of the inner hole of the spline, with the outer circle of the ground spline as the reference; after the inner hole of the spline is finished, dynamic balancing and material removal are performed to obtain the final transmission rod.

2. The method for machining a welded transmission rod to control the initial imbalance according to claim 1, characterized in that, The length of the mandrel (12) is greater than the length of the welded transmission rod. The mandrel (12) has a shoulder (14) at one end near the positioning stop and an external thread for mounting the bolt assembly at the other end away from the positioning stop.

3. The method for machining a welded transmission rod to control the initial imbalance according to claim 1, characterized in that, The lengths of the first transmission rod (1) and the second transmission rod (2) are different.

4. The method for machining a welded transmission rod to control the initial imbalance according to claim 1, characterized in that, A rough machining reference surface is provided at the end of the transmission rod welded part and near the positioning stop (10), and splines are machined at both ends of the transmission rod welded part according to the rough machining reference surface.

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