Efficient and high-precision grinding method and system for turbine disc mortise face through robot

Abstract

The invention discloses an efficient and high-precision robot grinding method and system for a turbine disc mortise face, the system comprises a robot, a compliant actuator, a tool changing mechanism, a profiling tool, a clamp, a robot rotary table and a sensor system, and the grinding method comprises the following steps that S1, a turbine disc is installed through the clamp, and the robot controls the tool changing mechanism to clamp the tool; s2, feeding along the mortise surface of the turbine disc; s3, the robot controls the cutter to grind along the mortise surface of the turbine disc; s4, when the grinding of the tongue-and-groove surface of the single turbine disc is completed, the robot controls the cutter to retract along the tongue-and-groove surface of the turbine disc; s5, the robot rotary table rotates to switch the mortise face; s6, the tool abrasion condition is detected; s7, the steps S2-S6 are repeated till all the mortise faces of the whole turbine disc are ground; the machining process is more stable, force fluctuation is reduced, the machining precision and the surface quality are improved, and the machining efficiency is also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine turbine disk production, and in particular to a method for high-efficiency and high-precision robot grinding of the tongue and groove surface of a turbine disk. The present invention also relates to a robot system for the tongue and groove surface of a turbine disk. Background Art

[0002] The turbine is one of the important components of an aircraft engine. It forms high-temperature and high-pressure combustion gas in the engine combustion chamber to drive the turbine to rotate. The turbine consists of a turbine disc and turbine blades. The turbine blades are connected and installed with the tenon at their root and the tenon groove of the turbine disc. Among the many structures for connecting the blades and the wheel disc tenon groove, the longitudinal tree structure is widely used in aircraft engines due to its outstanding features such as full material utilization, ability to withstand large tensile loads and small axial dimensions.

[0003] The machining accuracy of the tenon and groove of the turbine disk of an aircraft engine is high. The tooth shape of the turbine disk usually has an oblique angle, so the tooth shape drawing direction of the turbine disk has a certain angle with the center axis of the turbine disk; the precision tenon and groove surface is complex and the technical difficulty is relatively high. In order to meet the requirements of the long life of the aircraft engine, conventional processing methods cannot meet the requirements. Therefore, it is necessary to ensure the grinding accuracy and efficiency of the tenon and groove of the turbine disk of an aircraft engine. The main reasons for the limited grinding accuracy and efficiency are as follows: the existing grinding method mainly relies on manual grinding, and the grinding force fluctuation and grinding angle are difficult to control; the grinding process of the turbine disk is a long and repetitive process, which puts higher requirements on the processing stability; in order to ensure the processing accuracy, the grinding tool and the turbine disk tenon and groove are tightly fitted, and the robot body is prone to interference and jamming when directly grinding, and the force control accuracy of the robot body is low and the force fluctuation during the grinding process is large.

[0004] The existing patent publication number CN108723481A discloses a method for processing a turbine disc tenon groove, including the following steps: 1) a rough drawing stroke, in which a groove is opened on a turbine disc blank along the tenon tooth top reference line; 2) a semi-finishing drawing stroke, in which cutting is performed at a preset tenon groove position on the side wall of the groove to form a tenon rough groove; 3) a finishing drawing stroke, in which cutting is continued on the basis of the tenon rough groove to obtain a tenon groove; the single broaching process of this patent will produce obvious knife marks (with a tactile feel) on the broached surface, and the presence of these knife marks directly affects the surface roughness of the tenon groove, resulting in poor surface morphology, surface stress presenting both tensile stress and compressive stress, and high dispersion (tensile stress +500MPa ~ compressive stress -500MPa), and will further affect the subsequent shot peening effect, resulting in the inability to completely cover the surface knife marks after shot peening, affecting the surface integrity of the part, and ultimately affecting the fatigue resistance of the part. Summary of the Invention

[0005] The present invention mainly addresses the problems in the existing technology of low efficiency of the grinding process of the turbine tenon and groove surface, difficulty in controlling the fluctuation of the grinding tension and the grinding angle, low force control accuracy of the robot body, and large force fluctuations during the grinding process. It provides a robot-based efficient and high-precision grinding method and system for the turbine disk tenon and groove surface.

[0006] In view of the above technical problems, the technical solutions of the present invention are as follows:

[0007] A method for high-efficiency and high-precision robot grinding of the tenon-groove surface of a turbine disc comprises a robot, a compliant actuator, a tool changer, a profiling tool, a fixture, a robot turntable, and a sensor system. The compliant actuator is fixed to the end of the robot via a pneumatic quick changer; the tool changer is connected to the end of the compliant actuator via a connector; the profiling tool is clamped at the end of the tool changer via a clamping jaw. The grinding method comprises the following steps:

[0008] S1. Install the turbine disc using the fixture, use the robot to position it and control the automatic tool changing mechanism to drive the clamping jaws to open and close to clamp the tool;

[0009] S2, the robot controls the profiling tool to feed along the tenon-groove surface of the turbine disc;

[0010] S3, performing posture control on the robot so that the profiling tool moves along the grinding direction of the turbine disc tenon groove surface, and performing constant force control by driving the compliant end effector, thereby achieving high-precision turbine disc tenon groove surface grinding through the movement of the robot along the grinding direction and the control of the force;

[0011] S4. When the grinding of the tenon groove surface of a single turbine disk is completed, the tool is withdrawn along the tenon groove surface of the turbine disk by robot control;

[0012] S5, the robot turntable rotates to switch the tongue and groove surface;

[0013] S6. Detecting the wear state of the tool. If the wear is too great, controlling the robot's main body posture and the gripper's opening and closing state to automatically change the tool;

[0014] S7. Repeat steps S2-S6 until all the tongue and groove surfaces of the entire turbine disk are ground.

[0015] Furthermore, in step S2 and step S4, the robot controls the grinding tool to contact the workpiece in a contactless, non-interference, and zero-force manner.

[0016] Furthermore, in step S3, the direction of the compliant movement and the angle of the tool changing mechanism perpendicular to the workpiece during processing have a certain deviation, so that the processing force is perpendicular to the working surface.

[0017] Furthermore, the tool changing mechanism includes an automatic tool changing mechanism, a high-precision turntable structure and a clamping jaw. The automatic tool changing mechanism uses pneumatic means to drive the opening and closing of the clamping jaw and the high-precision turntable structure.

[0018] Furthermore, the compliant actuator includes a synchronous belt servo platform, an elastic module and a mobile platform connector. The mobile platform connector connects the synchronous belt servo platform and the elastic module. By connecting the elastic module in series, the actuator end is passively compliant in the expected contact force direction; through the transmission of passive compliant force, the contouring tool maintains flexible contact with the workpiece to be processed. The compliant end actuator combined with the sensor system feedback can achieve high-precision grinding force control.

[0019] Furthermore, the mobile platform connector is connected to the force sensor, and the force sensor is connected to the tool changing mechanism via a connector.

[0020] Furthermore, in step S3, the motion trajectory of the robot control is realized after being shaped by an input shaper.

[0021] Furthermore, an input shaping trajectory control method is adopted to optimize the normal contact force and feed speed of the robot control.

[0022] Furthermore, in step S2, a grinding surface of a profiling tool is designed according to the tenon groove surface of the turbine disc, and a non-grinding surface of the profiling tool is cut out in reverse according to the shape of the tenon groove of the wheel disc.

[0023] Furthermore, a robot-based efficient and high-precision grinding system for the tenon and groove surface of a turbine disk adopts the robot-based efficient and high-precision grinding method for the tenon and groove surface of a turbine disk according to any one of claims 1-9.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention includes a robot, a compliant actuator, a tool changer, a profiling tool, a fixture, a robot turntable, and a sensor system. The compliant actuator is quickly pneumatically fixed to the end of the robot; the tool changer is connected to the end of the end effector via a connector; and the profiling tool is clamped at the end of the tool changer via a clamp. By designing a "robot + force-controlled compliant actuator + automatic tool changer + profiling tool" combination, it is used for efficient processing of the tenon and groove surfaces of turbine disks, and has stability and high efficiency.

[0026] 2. Through the automatic tool changing mechanism and process optimization design, the automatic tool changing mechanism is realized by pneumatic means and is used to drive the opening and closing of the clamping jaws. The high-precision turntable structure can adapt to the tenon and groove surfaces of turbine discs at different angles, thereby improving processing efficiency and adapting to high-intensity production needs.

[0027] 3. The robot trajectory is controlled by force-controlled compliant actuators and input shaping methods, making the machining process more stable and reducing force fluctuations.

[0028] 4. Through the specialized and improved tool and force-controlled end design, the force is ensured to be perpendicular to the grinding surface and zero-force feed is ensured, thus improving the processing accuracy and surface quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the overall structure of the system of the present invention;

[0030] Figure 2 This is a schematic structural diagram of a compliant actuator of the present invention;

[0031] Figure 3 is a process flow chart of the present invention;

[0032] Figure 4 It is a schematic structural diagram of the profiling tool of the present invention;

[0033] Figure 5 This is a schematic diagram of step S6 of the processing procedure of the present invention;

[0034] Figure 6 This is a schematic diagram of the actuator-tool-changing mechanism-profiling tool-turbine disc tenon-groove surface in which the machining force is perpendicular to the working surface of the present invention;

[0035] Figure 7 The force fluctuation before and after the shaping control is input for the application of the present invention;

[0036] Figure 8 Schematic diagram of the internal structure and connectors of the compliant end effector of the present invention.

[0037] In the above figure, 101. Robot; 102. Compliant actuator; 103. Tool changing mechanism; 104. Contour tool; 105. Turbine disc; 106. Fixture; 107. Robot turntable; 108. Sensor system; 201. Synchronous belt servo platform; 202. Elastic module; 203. Force sensor; 204. Mobile platform connector; 205. Connector; 206. Pneumatic quick change; 207. Gripper; 208. High-precision turntable mechanism; 209. Automatic tool changing mechanism. DETAILED DESCRIPTION

[0038] In order to clearly illustrate the technical features of the application scheme of the present invention, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0039] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0040] In addition, in the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0041] In this application, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0042] In this application, unless otherwise expressly specified and limited, a first feature "above" or "below" a second feature may be such that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, reference terms such as "one embodiment", "some embodiments", "example", "specific example" or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0043] Example 1

[0044] like Figure 1 - Figure 8As shown, a robot-based high-efficiency and high-precision grinding system for the tenon and groove surface of a turbine disc includes a robot 101, a compliant actuator 102, a tool changing mechanism 103, a profiling tool 104, a fixture 106, a robot turntable 107, and a sensor system 108. The compliant actuator 102 is fixed to the end of the robot 101 via a pneumatic quick changer 206; the tool changing mechanism 103 is connected to the end of the compliant actuator 102 via a connector 205; and the profiling tool 104 is clamped at the end of the tool changing mechanism 103 via a clamp 207.

[0045] like Figure 1 As shown, in this embodiment, the robot 101 is responsible for achieving the motion trajectory, the compliant actuator 102 controls the grinding force, and the tool changer 103 switches between different profiling tools 104 to automatically switch between different types of turbine disc groove surfaces. The profiling tool 104 is responsible for grinding the turbine disc groove surface, the fixture 106 is responsible for clamping the turbine disc 105, and the robot turntable 107 is responsible for switching and rotating the turbine disc groove surface. The sensor system 108 includes a force sensor 203 for force monitoring and feedback control, and a camera for detecting the wear status of the profiling tool 104.

[0046] like Figure 1 and Figure 3 As shown in FIG, a compliant end effector mechanism has a series elastic actuator structure inside, which ensures force compliance and thus force accuracy, and at the same time encapsulates the elastic actuator. Figure 8 As shown, the compliant end effector is a force control device based on a series elastic actuator, which includes a synchronous belt servo platform 201, an elastic module 202, and a mobile platform connector 204. The mobile platform connector 204 is connected to the synchronous belt servo platform 201 and the elastic module 202, and the elastic module 202 is used to make the actuator end passively compliant in the direction of its contact force; the mobile platform connector 204 is connected to the force sensor 203, and the force sensor 203 is connected to the tool changing mechanism 103 through the connector 205; through the transmission of passive compliant force, the profiling tool 104 maintains flexible contact with the workpiece to be processed, and the compliant end effector combined with the feedback of the sensor system 108 can achieve high-precision grinding force control.

[0047] like Figure 1 and Figure 8 As shown, the tool changing mechanism 103 includes an automatic tool changing mechanism 209, a high-precision turntable structure 208 and a clamp 207. The automatic tool changing mechanism 209 adopts a pneumatic method to realize and drive the clamp 207 to open and close, and the high-precision turntable structure 208 is used to adapt to the tenon groove surface of the turbine disc at different angles.

[0048] like Figure 4As shown, the grinding surface of the profiling tool is designed according to the tenon groove surface of the turbine disk, and the non-grinding surface is cut out in the opposite direction according to the shape of the tenon groove of the wheel disk to ensure that the tool effectively fits the tenon groove surface of the turbine disk and no interference occurs when the robot feeds.

[0049] Example 2

[0050] like Figure 3 As shown, a robot-based high-efficiency and high-precision grinding method for the tongue and groove surface of a turbine disk comprises the following steps:

[0051] S1. Install the turbine disc through the fixture, use the robot to position it and control the automatic tool change mechanism to drive the clamping jaws to open and close to clamp the tool;

[0052] S2, using the robot to control the profiling tool to feed along the tenon groove surface of the turbine disc;

[0053] S3. The robot is posture-controlled so that the profiling tool moves along the grinding direction of the turbine disc groove surface, and the compliant end effector is driven to perform constant force control. The high-precision grinding of the turbine disc groove surface is achieved through the movement of the robot along the grinding direction and the control of the force.

[0054] S4. When the grinding of the tenon groove surface of a single turbine disk is completed, the tool is withdrawn along the tenon groove surface of the turbine disk by robot control;

[0055] S5. Using the robot turntable to rotate and switch the mortise and tenon surface;

[0056] S6. Detect tool wear. If the wear is too severe, control the robot's main body posture and the gripper's opening and closing status to automatically change the tool.

[0057] S7. Repeat steps S2-S6 until all the tongue and groove surfaces of the entire turbine disk are ground.

[0058] In this embodiment, in steps S2 and S4, when the profiling tool feeds along the turbine tenon groove surface, the robot controls the grinding tool to feed and contact the workpiece in a contactless, non-interference, zero-force manner; when retracting along the turbine disk tenon groove surface, the tool retracts from the workpiece in a zero-force manner.

[0059] like Figure 6 As shown, in step S3, under the coordinated action of the robot, its compliant end effector and the force control sensor, the compliant motion direction and the angle of the tool changing mechanism perpendicular to the workpiece during processing have a certain deviation, so that the processing force is perpendicular to the working surface.

[0060] like Figure 7 As shown, in step S3, the motion trajectory controlled by the robot is realized after being shaped by the input shaper; the input shaping trajectory control method is adopted to optimize the control of the normal contact force and feed speed, further improving the grinding force control accuracy.

[0061] Example 3

[0062] like Figure 1 - Figure 8 As shown, a robot-based high-efficiency and high-precision grinding system for the tenon and groove surface of a turbine disc includes a robot 101, a compliant actuator 102, a tool changing mechanism 103, a profiling tool 104, a fixture 106, a robot turntable 107, and a sensor system 108. The compliant actuator 102 is fixed to the end of the robot 101 via a pneumatic quick changer 206; the tool changing mechanism 103 is connected to the end of the compliant actuator 102 via a connector 205; and the profiling tool 104 is clamped at the end of the tool changing mechanism 103 via a clamp 207.

[0063] In this embodiment, in order to realize the compliance of the compliant actuator and ensure force compliance, an elastic element, specifically a spring or rubber, may be used; a force sensor may be used to monitor the output force in real time or an intelligent algorithm, such as fuzzy control or neural network control, may be used.

[0064] Obviously, the above-described embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. A person skilled in the art would be able to make other variations or modifications based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A robot-based high-efficiency and high-precision grinding method for the tongue and groove surface of a turbine disk, characterized in that: The invention comprises a robot, a compliant actuator, a tool changing mechanism, a profiling tool, a fixture, a robot turntable and a sensor system. The compliant actuator is fixed to the end of the robot through a pneumatic quick change; the tool changing mechanism is connected to the end of the compliant actuator through a connecting piece; the profiling tool is clamped at the end of the tool changing mechanism through a clamp; and the grinding method comprises the following steps: S1, installing the turbine disc by the fixture, using the robot to position it and control the automatic tool changing mechanism to drive the clamping jaws to open and close to clamp the tool; S2, the robot controls the profiling tool to feed along the tenon and groove surface of the turbine disc; S3, controlling the posture of the robot so that the profiling tool can move along the grinding direction of the tenon groove surface of the turbine disc, and driving the compliant end effector to perform constant force control, so that high-precision grinding of the tenon groove surface of the turbine disc can be achieved through the movement of the robot along the grinding direction and the control of the force; S4. When the grinding of the tenon groove surface of a single turbine disk is completed, the robot is used to control the tool to withdraw along the tenon groove surface of the turbine disk; S5, the robot turntable rotates to switch the tongue and groove surface; S6, detecting the wear state of the tool, and if the wear is too great, controlling the robot body posture and the opening and closing state of the gripper to automatically change the tool; S7, repeating the steps S2-S6 until all the tongue and groove surfaces of the entire turbine disk are ground.

2. A robot efficient and high-precision grinding method for the tongue and groove surface of a turbine disk according to claim 1, characterized in that: In step S2 and step S4, the robot controls the grinding tool to contact the workpiece in a non-contact, non-interference, and zero-force manner.

3. The method for high-efficiency and high-precision robot grinding of the tongue and groove surface of a turbine disk according to claim 1, characterized in that: In step S3, there is a certain deviation between the movement direction of the compliant actuator and the angle of the tool changing mechanism perpendicular to the workpiece during processing, so that the processing force is perpendicular to the working surface.

4. A robot efficient and high-precision grinding method for the tongue and groove surface of a turbine disk according to claim 3, characterized in that: The tool changing mechanism comprises an automatic tool changing mechanism, a high-precision turntable structure and a clamping jaw. The automatic tool changing mechanism adopts a pneumatic method to drive the opening and closing of the clamping jaw and the high-precision turntable structure.

5. The method for high-efficiency and high-precision robot grinding of the tongue and groove surface of a turbine disk according to claim 3, characterized in that: The compliant actuator includes a synchronous belt servo platform, an elastic module and a mobile platform connector. The mobile platform connector connects the synchronous belt servo platform and the elastic module. By connecting the elastic module in series, the actuator end achieves passive compliance in the expected contact force direction.

6. A robot efficient and high-precision grinding method for the tongue and groove surface of a turbine disk according to claim 6, characterized in that: The mobile platform connecting piece is connected to the force sensor, and the force sensor is connected to the tool changing mechanism through the connecting piece.

7. The method for high-efficiency and high-precision robot grinding of the tongue and groove surface of a turbine disk according to claim 1, characterized in that: In step S3, the motion trajectory of the robot control is realized after being shaped by an input shaper.

8. A robot efficient and high-precision grinding method for turbine disc tongue and groove surfaces according to claim 7, characterized in that: An input shaping trajectory control method is adopted to optimize the normal contact force and feed speed of the robot control.

9. The method for high-efficiency and high-precision robot grinding of the tongue and groove surface of a turbine disk according to claim 1, characterized in that: In the step S2, the grinding surface of the profiling tool is designed according to the tenon groove surface of the turbine disk, and the non-grinding surface of the profiling tool is cut out in reverse according to the shape of the tenon groove of the wheel disk.

10. A robot efficient and high-precision grinding system for turbine disc tongue and groove surfaces, characterized in that: The grinding method according to any one of claims 1 to 9 is adopted.

Images