A method for repairing a traction motor mounting hole of a motor train unit frame

Abstract

The application provides a kind of motor car frame traction motor mounting hole repair method to solve the repair problem that cannot be carried out due to the limitation of small distance between hole and base edge and hole depth in the prior art.First, the inner surface of the mounting hole is exposed by cutting the corner of the frame, laser stereoscopic forming technology is used to repair the inner surface of the mounting hole by laser cladding, then the corner of the frame is machined to a certain bevel, then the laser additive is filled in the bevel area, and finally the mounting hole and the frame shell are machined to restore the design size.The inner surface of the damaged mounting hole is not machined, but repaired by laser cladding, which minimizes the impact of the repair process on the frame base, especially the service performance of the narrow area of the frame edge size.

Description

Technical Field

[0001] This invention belongs to the field of laser repair and remanufacturing, and specifically relates to a method for repairing the mounting holes of traction motors for locomotive bases of high-speed trains. Background Technology

[0002] Traction motors are crucial components of high-speed trains. During operation, the traction motor converts electrical energy into mechanical energy to drive the train. The working environment of high-speed train traction motors is harsh, including large load variations, severe impacts and vibrations, and significant corrosion from wind, sand, rain, snow, and acidic / alkaline gases. Therefore, to ensure safe operation, traction motors must be disassembled and inspected after a train has traveled one million kilometers.

[0003] The traction motor is installed using a frame-suspended, fully suspended method, requiring hoisting through mounting holes during installation. After a certain number of disassemblies, scratches easily appear on the inner surface of the mounting holes, causing deviations in the inner diameter and failing to meet assembly precision requirements. In the past, after a certain number of disassemblies or when damage was detected on the inner surface of the mounting holes, a new motor was typically replaced to ensure the normal operation of the train. However, with the increasing number of high-speed trains undergoing maintenance in recent years, the number of damaged motor housings has risen sharply. Since existing train motor housings are manufactured as a single casting, processing costs are high. Scrapping and replacing them or remelting the housings would place significant pressure on material reserves and economic costs. Therefore, partial repair and remanufacturing of the housings to restore their original precise dimensions and service performance is an effective way to reduce losses and ensure the long-term continuous use of the train.

[0004] Due to the characteristics of the traction motor frame material, structure, and damage, traditional repair methods are quite challenging. First, the traction motor is made of ductile iron, possessing excellent shock absorption and low-temperature mechanical properties. Second, to meet actual working needs and reduce material weight to save energy, the frame structure is highly complex, requiring extremely high dimensional accuracy at each connection point. The mounting hole diameter is only 20mm, the hole depth is 35-40mm, and the distance from the frame edge is 10mm. Furthermore, the material around the mounting hole bears the responsibility of support, stress, and shock absorption during hoisting, requiring its structure and performance to meet requirements. These limitations significantly increase the difficulty of repair process design. Third, the damage to the inner surface of the mounting hole caused by actual motor disassembly is often very minor, generally not exceeding 0.2mm in depth. Therefore, the following requirements should be noted when repairing mounting holes: (1) The repair area should only include the inner surface of the mounting hole and a small area near the mounting hole, so as to avoid the mechanical and thermal effects of the repair from affecting other parts, and ensure that the part between the hole and the edge of the base maintains the required mechanical properties to withstand force and vibration; (2) After repair, the dimensions of the inner diameter of the mounting hole, the edge of the base, and other parts should strictly meet the design requirements. In summary, current hole repair methods (such as plugging holes, friction stir welding, etc.) cannot be carried out due to the limitations of hole depth and small distance between the hole and the edge of the base. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for repairing the mounting holes of traction motors for locomotive bases, so as to solve the problem that the repair of holes in traction motor bases in the prior art is impossible due to limitations such as hole depth and small distance between the hole and the edge of the base.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A method for repairing the mounting hole of a traction motor on a high-speed train locomotive base includes the following steps:

[0008] Step 1: Cut the base body, with the cut surface intersecting the mounting holes on the base body; the base body is divided into the base body and the base corners; the two cut surfaces of the base body are the first cut surface and the second cut surface, and the two cut surfaces of the base corners are the third cut surface and the fourth cut surface, with the first cut surface and the third cut surface corresponding to each other, and the second cut surface and the fourth cut surface corresponding to each other;

[0009] Step 2: Form a cladding layer on the inner surface of the mounting holes in the base body, and form a cladding layer on the inner surface of the mounting holes in the corners of the base.

[0010] Step 3: Determine the cutting surfaces to be processed based on the inclination direction of the four cutting surfaces relative to the corners of the machine base, and then process them.

[0011] Step 4: Place the machine base corners back in their original positions. The first and third cut surfaces after processing form bevels, and the second and fourth cut surfaces after processing form bevels. Repair the two bevels by laser cladding, and the repair of the machine base base is completed.

[0012] A further improvement of the present invention is that:

[0013] Preferably, in step 2, a cladding layer is formed on the inner surface of the mounting hole by laser cladding.

[0014] Preferably, in step 4, after installing the cylindrical support block in the mounting hole of the base body, the corner of the base is placed in its original position for laser cladding repair.

[0015] Preferably, in step 4, after installing the cylindrical support block in the mounting hole of the base body, the contact edge between the support block and the first cutting surface is connected by single-pass laser cladding, and the contact edge between the support block and the second cutting surface is connected by single-pass laser cladding.

[0016] Preferably, the edge of the cylindrical support block and the inner surface of the mounting hole are fitted with a clearance.

[0017] Preferably, the height of the cylindrical support block is equal to the height of the mounting hole.

[0018] Preferably, in step 4, the contact edge between the support block and the third cutting surface is connected by single-pass laser cladding, and the contact edge between the support block and the fourth cutting surface is connected by single-pass laser cladding.

[0019] Preferably, after step 4, after repairing the two bevels, the excess cladding layer and cylindrical support block are removed by machining.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention provides a method for repairing the mounting hole of a traction motor in a high-speed train base, solving the problem that existing technologies cannot perform repairs due to limitations in hole depth and the small distance between the hole and the base edge. First, the inner surface of the mounting hole is exposed by cutting the corner of the base. Laser cladding repair is then performed on the inner surface of the mounting hole using laser stereolithography. Next, a bevel is machined at the corner of the base. A support block is added inside the mounting hole to place the cut corner back in place. Laser additive manufacturing is then used to fill the beveled area. Finally, machining is performed to restore the mounting hole and the base shell to their designed dimensions. This invention avoids machining the damaged inner surface of the mounting hole, directly performing laser cladding repair, thus minimizing the impact of the repair process on the base substrate, especially preserving the service performance of the narrow edge area of ​​the base. The machined bevel facilitates complete laser melting, allowing molten droplets to penetrate deep into the support block surface during laser repair, improving surface bonding. Subsequent machining yields a smooth and flat inner surface. This method can adjust the repair materials and process parameters to obtain the repair area structure that best matches the target repair effect, depending on the different damage conditions. It can handle damage of various types and sizes, and has wider process applicability. This method overcomes the limitations of the repair process design imposed by the large depth of the mounting hole and the small distance between the hole and the edge of the base, ensuring the service performance of the base edge substrate. This method does not perform machining on the inner surface of the damaged mounting hole, but uses laser cladding repair to ensure repair quality and obtain a well-bonded repair interface. This method leaves machining allowance after repair, which is conducive to the rapid and accurate restoration of the original part size. This method has a simple process and fewer steps, minimizing the impact of the repair process on the base substrate, especially preserving the service performance of the narrow area at the edge of the base.

[0022] Furthermore, depending on the different cut surfaces, the cut surfaces can be selectively machined so that subsequent cut surfaces can form a bevel shape.

[0023] Furthermore, the cut surface is perpendicular to the upper surface of the mounting hole base at the bottom, which facilitates subsequent machining processes.

[0024] Furthermore, this method can obtain the repair area tissue that best meets the target repair effect by adjusting the repair materials and process parameters according to different damage conditions. It can cope with damage of various types and sizes, and is more convenient to operate and has a wider range of process applicability.

[0025] Furthermore, this method introduces cylindrical support blocks during the welding process of the machine base corners, which is beneficial for the positioning of the machine base corners. Attached Figure Description

[0026] Figure 1 A flowchart for repairing mounting holes;

[0027] Figure 2This is a partial schematic diagram of the workpiece after the inner surface of the mounting hole has been exposed;

[0028] Figure 3 This is a schematic diagram of bevel filling, where the arrows indicate the scanning direction.

[0029] Figure 4 This is a partial schematic diagram of the workpiece after the bevel has been filled, where the dashed lines represent the filled area;

[0030] Wherein, 1-base body; 2-mounting hole; 3-base corner; 4-cladding layer; 5-V-shaped bevel cutting block; 6-support block; 7-bevel; 8-base body; 9-first cutting surface; 10-second cutting surface; 11-third cutting surface; 12-fourth cutting surface. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings:

[0032] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] This invention discloses a method for repairing the mounting holes of a traction motor base in a high-speed train. See [link to relevant documentation]. Figure 1 This includes the following steps:

[0034] S1: Determine the damage type of the inner surface of the mounting hole 2 in the traction motor base 1. Determine the area and depth of the damaged area through observation, measurement and non-destructive testing. The area, location and shape of the damaged area can determine the subsequent cutting position. If the damage is a strip crack and is biased towards the edge, it can be directly cut off at the crack position. At the same time, the damage depth of the inner surface crack can determine the subsequent laser cladding repair process.

[0035] S2: First, cut the base corner 3 along the edge of the mounting hole 2. The two cut surfaces are perpendicular to the horizontal plane of the substrate, and each cut surface intersects the mounting hole 2. Cut along the center perpendicular line to expose all the inner surfaces of the mounting hole 2. Grind and clean the two inner surfaces. At this point, the entire base 1 is divided into the body 8 and the base corner 3. The two cut surfaces of the base body 8 are the first cut surface 9 and the second cut surface 10, and the two cut surfaces of the base corner 3 are the third cut surface 11 and the fourth cut surface 12. The first cut surface 9 and the third cut surface 11 match, and the second cut surface 10 and the fourth cut surface 12 match. The outer edges of the first cut surface 9 and the third cut surface 11 are closer to the base body 8 relative to their inner edges, and the outer edges of the second cut surface 10 and the fourth cut surface 12 are closer to the base body 8 relative to their respective inner edges.

[0036] S3: Laser cladding is performed on the inner surface of the mounting hole 2 using laser stereolithography technology. Specifically, a cladding layer 4 of a certain thickness is formed on all the inner surfaces of the mounting hole 2 in the machine base corner 3 and the machine base base 1.

[0037] Specifically, the laser cladding process parameters are related to the damage depth. Different remelting and repair depths are achieved by matching three process parameters: powder feed rate, laser power, and scanning speed. Repair of different damage thicknesses is achieved by utilizing substrate remelting and material mutual solubility.

[0038] S4: Based on the original cutting conditions of the four cutting surfaces, proceed with processing. If both the first cutting surface 9 and the third cutting surface 11 are perpendicular to the edge of the base body 8, then both the first cutting surface 9 and the third cutting surface 11 need to be machined so that they can form a bevel structure after combination. If the first cutting surface 9 protrudes outward from the inside relative to the outer edge of the base body 8, then the third cutting surface 11 protrudes outward from the outside relative to the outer edge of the base corner 3, then the third cutting surface 11 needs to be cut. If the first cutting surface 9 protrudes outward from the outside relative to the outer edge of the base body 8, then the third cutting surface 11 protrudes inward from the outside relative to the outer edge of the base corner 3, then the first cutting surface 9 needs to be cut. The purpose of the above process is to enable the first cutting surface 9 and the third cutting surface 11 to form a bevel structure after the second cutting process. The second cutting surface 10 and the fourth cutting surface 12 are processed in the same way, that is, the V-shaped bevel cutting block 5 is removed, and then the bevel surfaces (the fifth cutting surface 13 and the sixth cutting surface 14) are polished and cleaned.

[0039] S5: Grind and clean the machine base cutting surfaces (first cutting surface 9 and second cutting surface 10), install a cylindrical support block 6 in the machine base mounting hole 2, and use laser stereolithography technology to perform single-pass laser cladding connection between the machine base cutting surfaces (first cutting surface 9 and second cutting surface 10) and the contact edge of the support block 6; the diameter of the support block 6 is slightly smaller than the diameter of the mounting hole 2 after cladding, and the two are clearance fit, and the height of the support block 6 is the same as the height of the mounting hole 2.

[0040] S6: Place the base corner 3 in the original position of the base body 1. The first cutting surface 9 and the third cutting surface 111 after cutting form a bevel. The second cutting surface 10 and the fourth cutting surface 12 after cutting form a bevel. Use laser stereoforming technology to connect the bevel surface of the base corner with the contact edge of the support block 6 using single-pass laser cladding.

[0041] S7: Perform laser cladding repair on the notch between the base 1 and the corner 3 of the base;

[0042] S8: According to the requirements of the original drawings, the mounting holes and the surface of the base are machined to remove the excess cladding layer, so that the mounting holes 2 and the base shell are restored to the design dimensions.

[0043] Example 1

[0044] S1: Determine the type of damage to the inner surface of the traction motor mounting hole. Through observation, measurement, and non-destructive testing, determine that there is a single micro-scratch on the inner wall of the mounting hole, with a scratch depth of approximately 0.1 mm.

[0045] S2: Cut along the perpendicular line from the center of the mounting hole to the two edges of the traction motor, and the resulting workpiece shape is as follows. Figure 2 As shown. The inner surface of the mounting hole is cleaned with acetone or similar substances to remove oil and impurities, and no further machining is performed.

[0046] S3: Pre-treat the repair and filling materials by placing the metal powder in a vacuum drying oven and drying it at 150°C for 2 hours to remove any moisture that may be present on the powder surface.

[0047] Based on the damage, a single-pass cladding repair path was selected to repair the inner surface of the mounting hole. The process parameters were: laser power 1500W, scanning rate 10mm / s, powder feeding rate 5g / min, and spot diameter 3mm. This ensured that the length of the single-pass cladding layer was greater than the scratch length, the remelting depth of the substrate was greater than the damage depth, and the height of the cladding layer exceeded the original size by 0.2±0.1mm.

[0048] S4: Process the two cutting surfaces (a3 and a4) of the machine base corner 3 to form a bevel, that is, cut off the V-shaped bevel cutting block 5, and then grind and clean the bevel.

[0049] S5: Grind and clean the machine base cutting surfaces (a1 and a2), install a cylindrical support block 6 in the machine base mounting hole 2, and use laser stereolithography technology to perform single-pass laser cladding connection between the machine base cutting surfaces (a1 and a2) and the contact edge of the support block 6.

[0050] S6: Place the base corner 3 in the original position of the base 1, and use laser three-dimensional forming technology to perform single-pass laser cladding connection between the bevel surface (a5 and a6) of the base corner and the contact edge of the support block 6;

[0051] S7: The V-shaped bevel is filled using laser stereolithography, with an overlap rate of 30%–50%, completely repairing the two transition bevels. The filled area exceeds the original size in all directions, with a machining allowance exceeding the original size by 0.2 ± 0.1 mm. Figure 4 As shown, the dashed line represents the filled area 7;

[0052] S8: According to the requirements of the original drawings, perform surface machining on the mounting holes and traction motor housing to remove excess cladding layer and restore the mounting holes and base housing to the design dimensions; use fluorescence to perform non-destructive testing on the surface of the machined area to check for unfused holes and cracks; use eddy current testing to determine defects such as holes and cracks inside the repair area.

[0053] Example 2

[0054] S1: Determine the type of damage to the inner surface of the traction motor mounting hole. Through observation, measurement, and non-destructive testing, determine that there is a single micro-scratch on the inner wall of the mounting hole, with a scratch depth of approximately 0.1 mm.

[0055] S2: Cut along the perpendicular line from the center of the mounting hole to the two edges of the traction motor, and the resulting workpiece shape is as follows. Figure 2 As shown. The inner surface of the mounting hole is cleaned with acetone or similar substances to remove oil and impurities, and no further machining is performed.

[0056] S3: Pre-treat the repair and filling materials by placing the metal powder in a vacuum drying oven and drying it at 150°C for 2 hours to remove any moisture that may be present on the powder surface.

[0057] Based on the damage, a single-pass cladding repair path was selected to repair the inner surface of the mounting hole. The process parameters were: laser power 1500W, scanning rate 10mm / s, powder feeding rate 5g / min, and spot diameter 3mm. This ensured that the length of the single-pass cladding layer was greater than the scratch length, the remelting depth of the substrate was greater than the damage depth, and the height of the cladding layer exceeded the original size by 0.2±0.1mm.

[0058] S4: The two third cutting surfaces 11 and the fourth cutting surfaces 12 (a3 and a4) of the machine base corner 3 are machined to form beveled surfaces, that is, the V-shaped bevel cutting block 5 is removed, and then the beveled surfaces are ground and cleaned; the first cutting surface 9 and the second cutting surface 10 (a1 and a2) of the machine base body 8 are machined to form beveled surfaces, and then the cut beveled surfaces are ground and cleaned.

[0059] S5: Install a cylindrical support block 6 in the mounting hole 2 of the base, and use laser stereolithography technology to connect the first cutting surface 9 and the second cutting surface 10 (a1 and a2) with the contact edge of the support block 6 by single-pass laser cladding.

[0060] S6: Place the base corner 3 in the original position of the base 1, and use laser stereolithography technology to connect the third cutting surface 11 and the fourth cutting surface 12 (a3 and a4) of the base corner 3 with the contact edge of the support block 6 using single-pass laser cladding.

[0061] S7: The V-shaped bevel is filled using laser stereolithography, with an overlap rate of 30%–50%, completely repairing the two transition bevels. The filled area exceeds the original size in all directions, with a machining allowance exceeding the original size by 0.2 ± 0.1 mm. Figure 4 As shown, the dashed line represents the filled area 7;

[0062] S8: According to the requirements of the original drawings, perform surface machining on the mounting holes and traction motor housing to remove excess cladding layer and restore the mounting holes and base housing to the design dimensions; use fluorescence to perform non-destructive testing on the surface of the machined area to check for unfused holes and cracks; use eddy current testing to determine defects such as holes and cracks inside the repair area.

[0063] Example 3

[0064] S1: Determine the type of damage to the inner surface of the traction motor mounting hole. Through observation, measurement, and non-destructive testing, determine that there is a single micro-scratch on the inner wall of the mounting hole, with a scratch depth of approximately 0.1 mm.

[0065] S2: Cut along the perpendicular line from the center of the mounting hole to the two edges of the traction motor, and the resulting workpiece shape is as follows. Figure 2 As shown. The inner surface of the mounting hole is cleaned with acetone or similar substances to remove oil and impurities, and no further machining is performed.

[0066] S3: Pre-treat the repair and filling materials by placing the metal powder in a vacuum drying oven and drying it at 150°C for 2 hours to remove any moisture that may be present on the powder surface.

[0067] Based on the damage, a single-pass cladding repair path was selected to repair the inner surface of the mounting hole. The process parameters were: laser power 1500W, scanning rate 10mm / s, powder feeding rate 5g / min, and spot diameter 3mm. This ensured that the length of the single-pass cladding layer was greater than the scratch length, the remelting depth of the substrate was greater than the damage depth, and the height of the cladding layer exceeded the original size by 0.2±0.1mm.

[0068] S4: The first cutting surface 9 and the second cutting surface 10 (a1 and a2) of the base body 8 are machined to form a bevel, and then the cut bevel is polished and cleaned.

[0069] S5: Install a cylindrical support block 6 in the mounting hole 2 of the base, and use laser stereolithography technology to connect the first cut surface 9 and the second cut surface 10 (a1 and a2) of the base with the contact edge of the support block 6 by single-pass laser cladding.

[0070] S6: Place the base corner 3 in the original position of the base 1, and use laser stereolithography technology to connect the third cutting surface 11 and the fourth cutting surface 12 (a3 and a4) of the base corner 3 with the contact edge of the support block 6 by single-pass laser cladding; at this time, the first cutting surface 9 and the third cutting surface 11 form a bevel, and the second cutting surface 10 and the fourth cutting surface 12 form a bevel.

[0071] S7: The V-shaped bevel is filled using laser stereolithography, with an overlap rate of 30%–50%, completely repairing the two transition bevels. The filled area exceeds the original size in all directions, with a machining allowance exceeding the original size by 0.2 ± 0.1 mm. Figure 4 As shown, the dashed line represents the filled area 7;

[0072] S8: According to the requirements of the original drawings, perform surface machining on the mounting holes and traction motor housing to remove excess cladding layer and restore the mounting holes and base housing to the design dimensions; use fluorescence to perform non-destructive testing on the surface of the machined area to check for unfused holes and cracks; use eddy current testing to determine defects such as holes and cracks inside the repair area.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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 repairing the mounting hole of a traction motor on a high-speed train locomotive base, characterized in that, Includes the following steps: Step 1, cut the machine base (1), the cutting surface intersects with the mounting hole (2) on the machine base (1); The base body (1) is divided into a base body (8) and a base corner (3); the two cut surfaces of the base body (8) are the first cut surface (9) and the second cut surface (10), and the two cut surfaces of the base corner (3) are the third cut surface (11) and the fourth cut surface (12), the first cut surface (9) and the third cut surface (11) correspond to each other, and the second cut surface (10) and the fourth cut surface (12) correspond to each other; Step 2: A cladding layer (4) is formed on the inner surface of the mounting hole (2) in the base body (8), and a cladding layer (4) is formed on the inner surface of the mounting hole (2) in the corner (3) of the base. Step 3: Determine the cutting surfaces to be processed based on the inclination direction of the four cutting surfaces relative to the edge of the machine base (3) and perform the processing. Step 4: Place the base corner (3) in its original position, and form a bevel on the first cut surface (9) and the third cut surface (11) after processing. Form a bevel on the second cut surface (10) and the fourth cut surface (12) after processing. Repair the two bevels by laser cladding. The repair of the base base (1) is completed. After installing the cylindrical support block (6) in the mounting hole (2) of the base body (8), place the base corner (3) in its original position and perform laser cladding repair; After repairing the two bevels, the excess cladding layer and cylindrical support block (6) are removed by machining.

2. The method for repairing the mounting hole of the traction motor for a high-speed train locomotive according to claim 1, characterized in that, In step 2, a cladding layer is formed on the inner surface of the mounting hole (2) by laser cladding.

3. The method for repairing the mounting hole of the traction motor for a high-speed train locomotive as described in claim 1, characterized in that, In step 4, after installing the cylindrical support block (6) in the mounting hole (2) of the base body (8), the contact edge of the cylindrical support block (6) and the first cutting surface (9) is connected by single-pass laser cladding, and the contact edge of the cylindrical support block (6) and the second cutting surface (10) is connected by single-pass laser cladding.

4. The method for repairing the mounting hole of the traction motor for a high-speed train locomotive according to claim 1, characterized in that, The edge of the cylindrical support block (6) and the inner surface of the mounting hole (2) are fitted with a clearance.

5. The method for repairing the mounting hole of the traction motor for a high-speed train locomotive as described in claim 1, characterized in that, The height of the cylindrical support block (6) is equal to the height of the mounting hole (2).

6. The method for repairing the mounting hole of the traction motor for a high-speed train locomotive according to claim 1, characterized in that, In step 4, the contact edges of the cylindrical support block (6) and the third cutting surface (11) are connected by single-pass laser cladding, and the contact edges of the cylindrical support block (6) and the fourth cutting surface (12) are connected by single-pass laser cladding.

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