A surface corrugation defect repair method and online repair system for electric upsetting parts

Abstract

The present invention belongs to the technical field of electric upsetting forming, and provides a method for repairing surface corrugation defects of electric upsetting parts. During the electric upsetting process, a laser cladding machine is used to fill metal powder into the surface corrugation defects of the electric upsetting parts. The present invention also provides an online repair system for surface corrugation defects of electric upsetting parts, including a defect recognition module, a trajectory control module and an operation control module; the defect recognition module is used to recognize and locate the surface corrugation defects of the electric upsetting parts; the trajectory control module is used to control the cladding head to rotate around the surface corrugation defects when the electric upsetting parts move axially in synchronization; the operation control module is used to control the cladding head to spray and melt metal powder when the cladding head rotates around the surface corrugation defects. The present invention has pioneered the repair of surface corrugation defects, reversed the situation that electric upsetting parts can only be scrapped after surface corrugations appear, reduced the scrap rate, improved the production quality of electric upsetting parts, and avoided folding defects that may occur in subsequent die forging processes.

Description

Technical Field

[0001] The invention belongs to the technical field of electric upsetting, and in particular relates to a surface corrugation defect repairing method and an online repairing system for an electric upsetting part. Background Art

[0002] As an efficient and precise metal plastic processing method, the electric upsetting process has been widely used in the production of marine low-speed engine valves. However, in the actual processing process, especially for parts with large aspect ratio or complex curved surface shape, wavy grooves (or corrugations, wavy surface defects) will appear during the electric upsetting process. This defect not only affects the appearance quality of the product, but also has a great impact on subsequent processing. The reasons for its occurrence may be uneven metal flow during the electric upsetting process, uneven distribution of current in the blank, improper die design, too fast or unstable electric upsetting speed, uneven cooling, etc. For the production of marine low-speed engine valves, this defect will cause wrinkle defects on the valve head during the subsequent die forging process in the subsequent processing, which will have a great impact on the quality of the valve. Therefore, once the electric upsetting parts have surface corrugation defects, they will be scrapped. At present, there is a lack of repair awareness and repair means. Summary of the invention

[0003] The invention provides a method for repairing surface corrugation defects of an electric upsetting part, so as to improve the production quality of the electric upsetting part and reduce the scrap rate of the part.

[0004] The present invention is achieved through the following technical solutions: A method for repairing surface corrugation defects of an electric upsetting part, during the electric upsetting process, a laser cladding machine is used to fill metal powder into the surface corrugation defects of the electric upsetting part.

[0005] Furthermore, the cladding head of the laser cladding machine rotates around the surface corrugation defect to perform the cladding operation while the electric upsetting piece moves axially in synchronization.

[0006] Furthermore, the metal powder is made of the same material as the electric upsetting piece.

[0007] Furthermore, the metal powder is Ni80A alloy powder.

[0008] The present invention also provides an online repair system for surface corrugation defects of electric upsetting parts, comprising a defect recognition module, a trajectory control module and an operation control module; Defect recognition module, used to identify and locate surface corrugation defects of electric upsetting parts; A trajectory control module for controlling the cladding head to rotate around the surface corrugation defect while synchronizing the axial movement of the electric upsetting piece; The operation control module is used to control the cladding head to spray and melt metal powder when the cladding head rotates around the surface corrugation defect.

[0009] Furthermore, there are two cladding heads distributed on both sides of the electric upsetting piece, and the rotation range of each cladding head is 180°.

[0010] Furthermore, the defect recognition module is used to identify the surface corrugation defect according to the contour of the electric upsetting part in the electric upsetting image, and the surface corrugation defect is a groove surrounding the surface of the electric upsetting part; the defect recognition module is used to locate the target groove according to the axial distance from the cladding head to each groove in the surface corrugation defect in the electric upsetting image, and the groove closest to the cladding head is the target groove.

[0011] Furthermore, the trajectory control module is used to control the cladding head to move axially to align with the target groove according to the predicted position of the target groove, and then control the cladding head to rotate around the surface corrugation defect when the synchronous electric upsetting piece moves axially.

[0012] Furthermore, the predicted position of the target groove is the current position of the target groove plus the axial displacement of the electric upsetting piece at the next moment.

[0013] Furthermore, the trajectory control module calculates the axial displacement of the cladding head at the next moment according to the current axial position coordinates of the cladding head and the axial position coordinates of the predicted position of the target groove.

[0014] Compared with the prior art, the beneficial effects of the present invention include: 1. The repair method of the present invention is carried out during the electric upsetting process, that is, laser cladding and electric upsetting are carried out simultaneously. The temperature of the electric upsetting parts during the electric upsetting process is relatively high. Compared with cladding the cooled electric upsetting parts, the metal powder can quickly combine with the electric upsetting parts in a molten state and form a more solid metallurgical bonding layer, thereby improving the quality of defect repair.

[0015] 2. During the electric stewing process, the additional heat brought by the cladding will also cause the temperature of the cladding substrate, i.e. the electric forging part, to rise again. The additional heat can increase the degree of dynamic recrystallization at the cladding site. Before the repair, the degree of dynamic recrystallization at this location is low. After the increase, the grain refinement of the workpiece can be increased to improve the quality of the workpiece.

[0016] 3. The present invention adopts a method combining laser cladding process with electric upsetting process, which can effectively improve the wave-shaped defects of the side wall of the blank appearing in the electric upsetting process, thereby avoiding the folding defects that may appear in the subsequent die forging process and causing the workpiece to be scrapped.

[0017] 4. The surface corrugation defect repairing system of the present invention can automatically locate the surface corrugation defect and control the cladding head to follow the movement of the surface corrugation defect. The present invention achieves a breakthrough from 0 to 1 in the repair of surface corrugation defects, reversing the situation that electric upsetting parts can only be scrapped after surface corrugations appear, reducing the scrap rate, improving the production quality of electric upsetting parts, and avoiding folding defects that may occur in the subsequent die forging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a physical schematic diagram of the surface ripple defect of the electric upsetting part during the electric upsetting process; Figure 2 It is a schematic diagram of the cladding operation performed by the cladding head; Figure 3 It is a control principle diagram of the surface corrugation defect repair system of the electric upsetting part in this specific implementation manner.

[0020] Figure 4 It is a process principle diagram of simultaneous electric upsetting and cladding in this specific implementation method. DETAILED DESCRIPTION

[0021] In the actual processing process, especially for parts with large aspect ratio or complex curved surface, surface ripple defects (also called ripples or wavy surface defects) will appear during the electric upsetting process. Figure 1 As shown in the figure, the surface corrugation defect is a groove surrounding the surface of the electric upsetting part, which can be one or more grooves. This defect not only affects the appearance quality of the workpiece, but also has a great impact on subsequent processing.

[0022] Example 1 In order to improve the production quality of electric upsetting parts, this embodiment provides a method for repairing surface corrugation defects of electric upsetting parts. During the electric upsetting process, a laser cladding machine is used to fill the surface corrugation defects of the electric upsetting parts with metal powder.

[0023] Considering that the surface corrugation defect exists in the radial 360° of the electric upsetting part, in order to completely fill the groove, there needs to be relative rotation between the cladding head and the electric upsetting part, that is, the electric upsetting part rotates or the cladding head rotates. Considering that if the electric upsetting part is clamped by the clamps at both ends during the electric upsetting process, if the electric upsetting part is rotated, it may cause unstable clamping, and then the axis of the blank may be offset, and even more serious instability of the blank may be caused, resulting in the scrapping of the workpiece. Considering the above reasons, the rotating cladding head solution was selected.

[0024] In order to avoid increasing the electric upsetting time and reducing production efficiency, the axial movement of the electric upsetting workpiece will not be suspended during the laser cladding process, which will cause the cladding position (i.e., the target groove position) to change in real time during the cladding process. Therefore, the cladding head is required not to simply rotate around the axis during operation, but to perform axial movement at the same time according to the real-time position of the target groove.

[0025] Preferably, in this embodiment, the cladding head of the laser cladding machine rotates around the surface corrugation defect to perform cladding operation while the electric upsetting piece moves axially in synchronization, and the cladding operation is to spray and melt the metal powder.

[0026] The principle of cladding operation, refer to Figure 2 As shown, a laser beam 9 is emitted from the center of the cladding head 10, and the laser quickly reaches the groove to form a molten pool 13. Powder feeding gas 8 is introduced into both sides of the cladding head 10, and a powder flow 12 is ejected. The powder flow 12 flows into the molten pool 13 and melts. The melted powder flow is combined with the electric upsetting piece to form a metallurgical layer.

[0027] In this embodiment, the metal powder is made of the same material as the electric upsetting piece.

[0028] This embodiment is used to repair the electric upsetting parts of a large marine low-speed engine valve. The electric upsetting parts are made of Ni80A alloy. During the cladding process, the temperature of the electric upsetting parts will be stable at about 700°C, which means that the cladding substrate does not need to be preheated, and a better cladding effect can be obtained by directly cladding. At the same time, the additional heat brought by the cladding will also increase the temperature of the cladding substrate, that is, the electric upsetting blank, which can enhance the plasticity of the blank and thus accelerate the process of electric upsetting.

[0029] Example 2 In order to implement the surface corrugation defect repairing method of the electric upsetting part in Example 1, this embodiment provides a surface corrugation defect repairing system of the electric upsetting part, and the surface corrugation defect repairing system of the electric upsetting part of this embodiment is configured in a laser cladding machine.

[0030] refer to Figure 3 As shown, the surface corrugation defect repair system of the electric upsetting part in this embodiment includes a defect recognition module, a trajectory control module and an operation control module; the trajectory control module and the operation control module are both configured in the controller.

[0031] Defect recognition module, used to identify and locate surface corrugation defects of electric upsetting parts; A trajectory control module for controlling the cladding head to rotate around the surface corrugation defect while synchronizing the axial movement of the electric upsetting piece; The operation control module is used to control the cladding head to spray and melt metal powder when the cladding head rotates around the surface corrugation defect.

[0032] In this embodiment, the defect recognition module is used to identify the surface corrugation defect according to the contour of the electric upsetting part in the electric upsetting image, and the surface corrugation defect is a groove surrounding the surface of the electric upsetting part; the defect recognition module is used to locate the target groove according to the axial distance from the cladding head to each groove in the surface corrugation defect in the electric upsetting image, and the groove closest to the cladding head is the target groove.

[0033] Identifying workpiece surface defects based on machine vision is a mature existing technology, for example, a metal surface defect identification method, device and equipment (CN118799649A), and its principle will not be repeated here.

[0034] The cladding head is installed on the robotic arm of the laser cladding machine, which can drive the cladding head to rotate and move axially. The motion trajectory control of the cladding head needs to be carried out in the coordinate system of the robotic arm of the laser cladding machine. In order to unify the coordinate system, the image coordinate system of the defect recognition module is converted to the coordinate system of the robotic arm in advance, so that the coordinates of each pixel in the electric upsetting image relative to the origin of the coordinate system of the robotic arm can be calculated in the electric upsetting image.

[0035] In this embodiment, the trajectory control module is used to control the cladding head to move axially to align with the target groove according to the predicted position of the target groove, and then control the cladding head to rotate around the surface corrugation defect when the synchronous electric upsetting piece moves axially.

[0036] Due to the axial movement of the electric upsetting piece, the target groove position in the current electric upsetting image will move axially with the electric upsetting piece at the next moment. Therefore, it is necessary to predict the target groove position at the next moment, that is, to calculate the predicted target groove position. The predicted target groove position is the current position of the target groove plus the axial displacement of the electric upsetting piece at the next moment. The axial displacement of the electric upsetting piece at the next moment is equal to the movement speed of the electric upsetting piece multiplied by the sampling time.

[0037] In this embodiment, the trajectory control module calculates the axial displacement of the cladding head at the next moment, x2-x1, according to the current axial position coordinate x1 of the cladding head and the axial position coordinate x2 of the predicted position of the target groove.

[0038] Considering that if only a single cladding head is used to rotate 360° for cladding operations, the scale of the supporting structure of the cladding head will be too large, which may be difficult to achieve.

[0039] In view of the above problems, consider using two cladding heads for simultaneous cladding. Preferably, refer to Figure 4 As shown, there are two cladding heads 10 distributed on both sides of the electric upsetting piece, and the rotation range of each cladding head 10 is 180°. Generally, a laser cladding machine has only one cladding head, so two laser cladding machines can be used to operate simultaneously.

[0040] The specific operation process is as follows: Start the electric upsetting machine, and the secondary transformer 2, the anvil electrode 7, the blank (i.e., the electric upsetting piece) and the clamping electrode 4 form a power-on circuit. At the same time, the anvil cylinder 1, the clamping cylinder 3 and the upsetting cylinder 6 remain stationary, and the electric upsetting piece is gradually preheated to the forging temperature range under the action of its own internal resistance and the Joule heat generated by the contact between the anvil electrode and the end face of the electric upsetting piece.

[0041] Then, the anvil cylinder 1 and the upsetting cylinder 6 move leftward at a speed and an upsetting force P respectively, and the hot end of the electric upsetting piece in the shape of a rod blank is locally gathered to form a "garlic head" under the upsetting force of the two cylinders.

[0042] As the electric upsetting piece is locally upsetting, when the defect recognition module detects the appearance of corrugated depressions on the surface of the electric upsetting piece, the current position of the target groove is located and sent to the trajectory control module. The trajectory control module calculates the predicted position of the target groove and the axial displacement of the cladding head at the next moment according to the current position of the target groove, and controls the cladding head to move to align with the target groove according to the axial displacement. After aligning with the target groove, the cladding head is controlled to rotate around the surface corrugation defect while synchronizing the axial movement of the electric upsetting piece. When the cladding head is started to rotate, the operation control module controls the cladding head to spray and melt the metal powder to fill and repair the target groove.

[0043] Considering that the groove depth on the side wall of the electro-upsetting workpiece may be too large, a single cladding (the cladding head rotates 180° around the target groove) cannot fill it, and since cladding and electro-upsetting are carried out simultaneously in this method, new grooves may appear after cladding due to the continuation of electro-upsetting.

[0044] In this embodiment, after a single cladding, the process will switch to the next target groove along the axial movement direction of the electric upsetting piece. In order to fully fill each groove, multiple cladding passes are required. The moving direction of the cladding trajectory can be reversed or the cladding head can be moved to the position relative to the "garlic head" when the cladding starts and cladding is performed again until there are no obvious wavy grooves on the side wall at the end of the electric upsetting. The defect recognition module judges based on the contour of the electric upsetting piece in the electric upsetting image: whether the contour line of the side wall of the electric upsetting piece is a straight line. If it is a straight line as a whole, the repair can be stopped. If there are still wavy line segments, the repair continues.

[0045] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.

Claims

1. A method for repairing surface corrugation defects of an electric upsetting part, characterized in that: During the electric upsetting process, a laser cladding machine is used to fill the surface corrugation defects of the electric upsetting parts with metal powder.

2. The method for repairing surface corrugation defects of an electric upsetting part according to claim 1, characterized in that: The cladding head of the laser cladding machine rotates around the surface corrugation defect to perform cladding operation while the electric upsetting piece moves axially in synchronization.

3. The method for repairing surface corrugation defects of an electric upsetting part according to claim 1, characterized in that: The metal powder is made of the same material as the electric upsetting piece.

4. The method for repairing surface corrugation defects of an electric upsetting part according to claim 1 or 3, characterized in that: The metal powder is Ni80A alloy powder.

5. A surface corrugation defect repair system for an electric upsetting part, characterized in that: It includes a defect recognition module, a trajectory control module and a laser cladding machine; Defect recognition module, used to identify and locate surface corrugation defects of electric upsetting parts; A trajectory control module for controlling the cladding head to rotate around the surface corrugation defect while synchronizing the axial movement of the electric upsetting piece; The operation control module is used to control the cladding head to spray and melt the metal powder when the cladding head rotates around the surface corrugation defect.

6. The surface corrugation defect repairing system of the electric upsetting part according to claim 4 is characterized in that: There are two cladding heads distributed on both sides of the electric upsetting piece, and the rotation range of each cladding head is 180°.

7. The online repair system for surface corrugation defects of electric upsetting parts according to claim 4 is characterized in that: The defect recognition module is used to identify surface corrugation defects according to the contour of the electric upsetting piece in the electric upsetting image, and the surface corrugation defects are grooves surrounding the surface of the electric upsetting piece; The defect recognition module is used to locate the target groove according to the axial distance from the cladding head to each groove in the surface corrugation defect in the electric upsetting image, and the groove closest to the cladding head is the target groove.

8. The online repair system for surface corrugation defects of electric upsetting parts according to claim 7 is characterized in that: The trajectory control module is used to control the cladding head to move axially to align with the target groove according to the predicted position of the target groove, and then control the cladding head to rotate around the surface corrugation defect when the synchronous electric upsetting piece moves axially.

9. The online repair system for surface corrugation defects of electric upsetting parts according to claim 8 is characterized in that: The predicted position of the target groove is the current position of the target groove plus the axial displacement of the electric upsetting piece at the next moment.

10. The online repair system for surface corrugation defects of electric upsetting parts according to claim 8, characterized in that: The trajectory control module calculates the axial displacement of the cladding head at the next moment according to the current axial position coordinates of the cladding head and the axial position coordinates of the predicted position of the target groove.

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