A segmented thermal spraying method for long-axis rotating workpieces

Abstract

This invention discloses a segmented thermal spraying method for long-axis rotating workpieces. The specific steps are: ① Based on the operating range of a thermal spraying robot, at least one groove is machined on the workpiece, dividing it into several spraying areas. The length of each spraying area separated by the groove does not exceed the operating range of the thermal spraying robot; ② Thermal spraying is performed on each spraying area separated by the groove, where the groove is located at the overlap of two thermal spraying areas. This invention segments the workpiece by machining grooves on its surface and uses these grooves as the starting or ending points for thermal spraying, ultimately resulting in a smooth thermal spray coating on the workpiece surface. This invention significantly reduces the difficulty of preparing the surface coating for long-axis rotating workpieces, is simple to operate, and greatly reduces costs.

Description

Technical Field

[0001] This invention belongs to the field of thermal spraying technology for material surfaces, and specifically relates to a thermal spraying method for long-axis rotating workpieces. Background Technology

[0002] Currently, thermal spraying technology is widely used in the preparation of protective layers on material surfaces due to its diverse energy density and spraying speed, as well as its applicability to raw material forms such as powders and filaments, and to materials such as metals, ceramics, and polymers. Thermal spraying technology involves heating powder materials (or filaments) to a molten or semi-molten state using a heat source (gas, liquid fuel, electric arc, plasma arc, laser, etc.), and then using the power of a flame or an external high-speed airflow to propel the sprayed material at a very high speed to collide with the substrate surface, thus depositing a coating with specified properties.

[0003] Due to the limited operating range of the thermal spraying robot during the thermal spraying process, it is difficult to achieve a one-time coating on the surface of long-shaft workpieces. If a segmented spraying method is used, bumps will inevitably appear at the overlapping areas, failing to meet the usage requirements. Achieving a successful one-time spraying requires specialized equipment or special spraying fixtures, which is both complex and costly. The applicant conducted relevant searches and currently has no patents related to segmented spraying of long-shaft rotating workpieces to overcome bumps at overlapping areas. Summary of the Invention

[0004] The problem this invention aims to solve is to provide a segmented thermal spraying method for long-axis rotating workpieces. This method divides the workpiece into segments by machining grooves on its surface, using these grooves as the starting or ending points for thermal spraying, ultimately resulting in a smooth thermal spray coating on the workpiece surface. This invention significantly reduces the difficulty of preparing coatings for long-axis rotating workpieces, is simple to operate, and greatly reduces costs.

[0005] The present invention discloses a segmented thermal spraying method for a long-axis rotating workpiece, the specific steps of which are: ① According to the operating range of the thermal spraying robot, at least one groove is processed on the workpiece to divide the workpiece into several spraying areas, wherein the length of each spraying area separated by the workpiece groove does not exceed the operating range of the thermal spraying robot; ② Thermal spraying is performed on each spraying area separated by the groove, wherein the location of the groove is the overlapping part of two thermal spraying areas.

[0006] Furthermore, in step ①: the depth of each trench = (1.1~1.2) * the thickness of the thermal spray coating, and the width of each trench = the diameter of the thermal spray spot.

[0007] Furthermore, in step ①: the junction between the groove and the workpiece surface is transitioned with a rounded or beveled corner.

[0008] Furthermore, in step ①: the number of segments of the workpiece is equal to the number of spraying times, the number of spraying times = [length of the workpiece / operating range of the thermal spraying robot], and the number of grooves = number of spraying times - 1.

[0009] Furthermore, when the operating range of the thermal spraying robot is less than the length of the workpiece, and the operating range of the thermal spraying robot is twice the length of the workpiece, and only one groove is set on the workpiece, the groove is located in the middle of the workpiece length. In this case, there are two spraying operations: the length of one spraying operation is from the left end of the workpiece to the right end of the groove; the length of the other spraying operation is from the left end of the groove to the right end of the workpiece.

[0010] Furthermore, when the operating range of the thermal spraying robot * 2 ≤ the length of the workpiece, the workpiece is provided with at least two grooves, wherein the distance between two adjacent grooves (including the width of the two grooves themselves) is slightly smaller than the operating range of the thermal spraying robot, the distance from the right side of the leftmost groove to the left end of the workpiece is ≤ the operating range of the thermal spraying robot, and the distance from the left end of the rightmost groove to the right end of the workpiece is ≤ the operating range of the thermal spraying robot.

[0011] Furthermore, in step ①: after the workpiece is machined into a groove, the groove is polished using an abrasive belt: the abrasive belt is the same width as the groove, it is wrapped inside the groove, the ends of the abrasive belt are clamped at the lathe tool post, and the workpiece is rotated to polish the groove.

[0012] Furthermore, the polishing process is divided into two steps: rough polishing and fine polishing. Rough polishing uses 240# abrasive belts, while fine polishing uses 400# to 600# abrasive belts.

[0013] Furthermore, when the long-axis rotating workpiece is an extruded mandrel with a length of 15m and the operating range of the thermal spraying robot is 6m, the corresponding process parameters for thermal spraying are: number of sprays = [length of workpiece / operating range of thermal spraying robot] = [15 / 6] = 3, number of grooves = number of sprays - 1 = 3 - 1 = 2; the coating thickness of the extruded mandrel is 0.10mm, the diameter of the thermal spraying spot is 12mm, so the groove depth is designed to be 0.11mm, the groove width is designed to be 12mm, the distance between two adjacent grooves is 4.5m, and the left and right sections are both 5.25m.

[0014] Furthermore, the segmented spraying method for the extruded mandrel is as follows: ① Based on the determined number of grooves, two grooves (groove one and groove two) are machined on the surface of the extruded mandrel, and then the grooves are polished; ② The surface of the extruded mandrel is subjected to three thermal spraying processes: First spraying: spraying starts from the left end of the extruded mandrel, with groove one as the spraying end position; Second spraying: spraying starts from groove one as the spraying start position and ends from groove two as the spraying end position; Third spraying: spraying starts from groove two as the spraying start position and ends at the right end of the extruded mandrel; This completes the preparation of the coating on the entire surface of the extruded mandrel.

[0015] This invention utilizes the operating range of a thermal spraying robot to machine grooves into the workpiece, dividing it into several spraying segments. This transforms a single spraying process into segmented spraying, with the grooves serving as the starting or ending points for thermal spraying. Therefore, no raised areas appear on the workpiece surface, resulting in a smooth coating across the entire workpiece. Consequently, this invention significantly reduces the difficulty of preparing coatings for long-axis rotating workpieces, eliminating the need for specialized spraying fixtures or modifications to spray gun equipment. It is simple to operate and greatly reduces costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating the segmentation of the groove machining process on a long-axis rotating workpiece in the method of the present invention. Detailed Implementation

[0017] Example 1

[0018] The present invention discloses a segmented thermal spraying method for a long-axis rotating workpiece, the specific steps of which are: ① According to the operating range of the thermal spraying robot, at least one groove is processed on the workpiece to divide the workpiece into several spraying areas, wherein the length of each spraying area separated by the workpiece groove does not exceed the operating range of the thermal spraying robot; ② Thermal spraying is performed on each spraying area separated by the groove, wherein the location of the groove is the overlapping part of two thermal spraying areas.

[0019] In the segmented spraying method of the present invention: although each groove is thermally sprayed twice as an overlapping part, since the groove is lower than the surface of the workpiece at both ends, the surface of the groove is finally flush with the surface of the workpiece as a whole without any protrusions, thus meeting the usage requirements.

[0020] Example 2

[0021] In the segmented thermal spraying method of the present invention: the depth of each groove = (1.1~1.2) * the thickness of the thermal spray coating, and the width of each groove = the diameter of the thermal spray spot.

[0022] To minimize coating overlap, the depth and width of the trenches are limited, which significantly reduces production costs while ensuring coating quality.

[0023] Example 3

[0024] In the segmented thermal spraying method of the present invention, the junction between the groove and the workpiece surface is transitioned with a rounded corner or a bevel.

[0025] Rounded or beveled transitions can prevent stress concentration at the bottom of the coating and ensure a tight bond between the coating and the trench.

[0026] Example 4

[0027] In the segmented thermal spraying method of this invention: the number of spraying times = [length of the workpiece / operating range of the thermal spraying robot], and the number of grooves = the number of spraying times - 1.

[0028] The number of spraying operations is calculated by dividing the workpiece length by the operating range of the thermal spraying robot, rounded up to the nearest integer. The number of grooves is the number of spraying operations minus 1. This method ensures that the number of grooves avoids bulging at the joints while minimizing the number of spraying operations, thereby improving spraying efficiency and reducing production costs.

[0029] Example 5

[0030] In the segmented thermal spraying method of the present invention: when the operating range of the thermal spraying robot is less than the length of the workpiece and less than the operating range of the thermal spraying robot * 2, and only one groove is set on the workpiece, the groove is located in the middle of the workpiece length, then there are two spraying operations: the length of the first spraying operation is from the left end of the workpiece to the right side of the groove; the length of the second spraying operation is from the left side of the groove to the right end of the workpiece.

[0031] In the segmented thermal spraying method of the present invention: when the operating range of the thermal spraying robot * 2 ≤ the length of the workpiece, the workpiece is provided with at least two grooves, wherein the distance between two adjacent grooves (including the width of the two grooves themselves) is slightly smaller than the operating range of the thermal spraying robot, the distance from the right side of the leftmost groove to the left end of the workpiece is ≤ the operating range of the thermal spraying robot, and the distance from the left end of the rightmost groove to the right end of the workpiece is ≤ the operating range of the thermal spraying robot.

[0032] When spraying in sections, one of two adjacent trenches is the starting position of the thermal spraying process, and the other trench is the ending position of the thermal spraying process.

[0033] Example 6

[0034] In the segmented thermal spraying method of the present invention: after the workpiece is machined into a groove, the groove is polished by using an abrasive belt: the abrasive belt is the same width as the groove and is wrapped inside the groove. The ends of the abrasive belt are clamped at the lathe tool post, and the workpiece is rotated to polish the groove.

[0035] Polishing is divided into two processes: rough polishing and fine polishing. Rough polishing uses 240# abrasive belts, while fine polishing uses 400# to 600# abrasive belts.

[0036] Example 7

[0037] like Figure 1As shown, the segmented thermal spraying method of this invention is used to process extruded mandrels (long-shaft rotating bodies), wherein: the outer diameter of the extruded mandrel before spraying is 141.82mm, the length of the extruded mandrel is 15 meters, the operating range of the thermal spraying robot is 6 meters, therefore the number of spraying times = [workpiece length / thermal spraying robot operating range] = [15 / 6] = 3, the number of grooves = number of spraying times - 1 = 3 - 1 = 2; the coating thickness of the extruded mandrel is 0.10mm, the diameter of the thermal spraying spot is 12mm, therefore the groove depth is designed to be 0.11mm, the groove width is designed to be 12mm, the distance between two adjacent grooves is 4.5m, and the left and right sections are both 5.25 meters.

[0038] The specific method for segmented thermal spraying of the above-mentioned extruded mandrel is as follows:

[0039] 1. Based on the determined number of grooves 2, process two grooves (groove one and groove two) on the surface of the extrusion mandrel, and then polish the grooves.

[0040] 2. Perform three thermal spraying processes on the surface of the extruded mandrel:

[0041] First spraying: Spraying begins from the left end of the extrusion mandrel, with groove one as the spraying end point; Second spraying: Spraying begins from groove one and ends from groove two; Third spraying: Spraying begins from groove two and ends at the right end of the extrusion mandrel; This completes the preparation of the coating on the entire surface of the extrusion mandrel.

[0042] As can be seen from the above, each groove, as the coating overlap area, was sprayed twice. After spraying, the diameter of groove one and groove two after spraying was Φ141.91mm, and the diameter of the extrusion mandrel was Φ141.92mm. The difference in surface diameter between the groove and the extrusion mandrel was only 0.01mm, which means that the groove area and the workpiece surface area are basically flat. The coating surface is flat and has no protrusions, which fully meets the design requirements.

[0043] Therefore, for long-axis rotating workpieces whose length exceeds the operating range of the thermal spraying robot, the segmented spraying method of this invention can be used for surface spraying. After spraying, no protrusions will appear on the workpiece surface, and the entire workpiece surface coating is smooth, meeting the usage requirements. The segmented spraying method of this invention significantly reduces the difficulty of preparing the surface coating for long-axis rotating workpieces, and requires no special spraying fixtures or modifications to the spray gun equipment, making it simple to operate and greatly reducing costs.

Claims

1. A segmented thermal spraying method for a long-axis rotating workpiece, comprising the following steps: ① Based on the operating range of a thermal spraying robot, at least one groove is machined on the workpiece to divide it into several spraying areas, wherein the length of each spraying area separated by the workpiece groove does not exceed the operating range of the thermal spraying robot; ② Thermal spraying is performed on each spraying area separated by the groove, wherein the location of the groove is the overlap of two thermal spraying areas; In step ①: the depth of each groove = (1.1~1.2) * the thickness of the thermal spray coating, and the width of each groove = the diameter of the thermal spray spot.

2. The segmented thermal spraying method according to claim 1, characterized in that: In step ①: the junction between the groove and the workpiece surface is transitioned with a rounded or beveled corner.

3. The segmented thermal spraying method according to claim 1, characterized in that: in step ①: the number of segments of the workpiece is equal to the number of spraying times, the number of spraying times = [length of the workpiece / operating range of the thermal spraying robot], and the number of grooves = number of spraying times - 1.

4. The segmented thermal spraying method according to claim 1, characterized in that: When the operating range of the thermal spraying robot is less than the length of the workpiece, and the operating range of the thermal spraying robot is twice the length of the workpiece, and only one groove is set on the workpiece, the groove is located in the middle of the workpiece length. At this time, there are two spraying operations: the length of the first spraying operation is from the left end of the workpiece to the right end of the groove; the length of the second spraying operation is from the left end of the groove to the right end of the workpiece.

5. The segmented thermal spraying method according to claim 1, characterized in that: When the operating range of the thermal spraying robot * 2 is less than or equal to the length of the workpiece, the workpiece has at least two grooves, wherein the distance between two adjacent grooves is slightly less than the operating range of the thermal spraying robot, the distance from the right side of the leftmost groove to the left end of the workpiece is less than or equal to the operating range of the thermal spraying robot, and the distance from the left end of the rightmost groove to the right end of the workpiece is less than or equal to the operating range of the thermal spraying robot; wherein the distance between two adjacent grooves includes the width of the two grooves themselves.

6. The segmented thermal spraying method according to claim 1, characterized in that: In step ①: After the workpiece is machined with grooves, the grooves are polished with a sanding belt: the sanding belt is the same width as the groove, and it is wrapped inside the groove. The beginning and end of the sanding belt are clamped at the lathe tool post, and the workpiece is rotated to polish the grooves.

7. The segmented thermal spraying method according to claim 6, characterized in that: Polishing is divided into two processes: rough polishing and fine polishing. Rough polishing uses 240# abrasive belts, while fine polishing uses 400# to 600# abrasive belts.

8. The segmented thermal spraying method according to claim 1, characterized in that: When the long-shaft rotating workpiece is an extruded mandrel with a length of 15m and the operating range of the thermal spraying robot is 6m, the corresponding process parameters for thermal spraying are: number of sprays = [length of workpiece / operating range of thermal spraying robot] = [15 / 6] = 3, number of grooves = number of sprays - 1 = 3 - 1 = 2; the coating thickness of the extruded mandrel is 0.10mm, the diameter of the thermal spraying spot is 12mm, so the groove depth is designed to be 0.11mm, the groove width is designed to be 12mm, the distance between two adjacent grooves is 4.5m, and the left and right sections are both 5.25m.

9. The segmented thermal spraying method according to claim 8, comprising the following steps: ① Based on the determined number of grooves, process two grooves (groove one and groove two) on the surface of the extrusion mandrel, and then polish the grooves. ② Perform three thermal spraying processes on the surface of the extruded mandrel: First spraying: spraying starts from the left end of the extruded mandrel, with groove one as the spraying end position; Second spraying: spraying starts from groove one as the spraying start position and ends from groove two as the spraying end position; Third spraying: spraying starts from groove two as the spraying start position and ends at the right end of the extruded mandrel; This completes the preparation of the coating on the entire surface of the extruded mandrel.

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