Weld groove forming method and hollow article

1. A weld groove forming method comprising:

(S 110 ) determining whether a side end of a pipe is configured to be processed into a form of a true circle by using a sensor robot; and

(S 220 ) forming a weld groove in a form of the true circle at the side end of the pipe by using an automatic beveling machine when the sensor robot determines that the side end of the pipe is configured to be processed into a form of the true circle in the step (S 110 ),

wherein the sensor robot is configured to (1) scan a side end of the hollow article in 2D or 3D, (2) store the scanned image of the hollow article as a measured image, (3) form a virtual image in a form of an annular ring, (4) overlap the virtual image with the measured image and determine whether the thickness portion of the virtual image is completely included in the thickness portion of the measured image, and also the thickness of the virtual image is in a range of 87.5% to 95% of an average thickness of the measured image, (5) determine that the side end of the hollow article is configured to be processed into a form of a true circle when the thickness portion of the virtual image is completely included in the thickness portion of the measured image, and also the thickness of the virtual image is in the range of 87.5% to 95% of the average thickness of the measured image, (6) determine the side end of the hollow article is not configured to be processed into a form of a true circle when the thickness portion of the virtual image is not completely included in the thickness portion of the measured image, or the thickness of the virtual image is in the range of 87.5% to 95% of the average thickness of the measured image, (7) transmit a beveling initiation signal to an automatic beveling machine, and (8) continuously measure the distance between the beveling blade of the automatic beveling machine and a to-be-beveled part of the hollow article and continuously transmit the measured value to the automatic beveling machine,

wherein the step (S 110 ) comprises:

(S 110 - 1 ) scanning the side end of the pipe to obtain a measured image in a form of an annular ring by using the sensor robot;

(S 110 - 2 ) overlapping the measured image with a predetermined virtual image in a form of an annular ring and also in a form of the true circle and determining whether the thickness portion of the virtual image is completely included in the thickness portion of the measured image, and also the thickness of the virtual image is in the range of 87.5% to 95% of the average thickness of the measured image by using the sensor robot; and

(S 110 - 3 ) determining that the side end of the pipe is configured to be processed into a form of the true circle by using the sensor robot, when the thickness portion of the virtual image is completely included in the thickness portion of the measured image, and also the thickness of the virtual image is in the range of 87.5% to 95% of the average thickness of the measured image in the step (S 110 - 2 ).

2. The weld groove forming method of claim 1 , wherein the step (S 120 ) is performed by cutting the inner wall, side end and outer wall of the pipe.

3. The weld groove forming method of claim 2 , wherein the step (S 120 ) comprises:

(S 120 - 1 ) slantly cutting the outer wall of the pipe from a first point far from the side end of the pipe to a second point close to the side end of the pipe, so that a thickness at the first point far from the side end of the pipe is thick, and a thickness at the second point close to the side end of the pipe is thin;

(S 120 - 2 ) slantly cutting the outer wall of the pipe which went through the step (S 120 - 1 ) from the second point far from the side end of the pipe to a third point close to the side end of the pipe, so that a thickness at the second point far from the side end of the pipe is thick, and a thickness at the third point close to the side end of the pipe is relatively thin;

(S 120 - 3 ) slantly cutting the outer wall of the pipe which went through the step (S 120 - 2 ) from the third point far from the side end of the pipe to a fourth point close to the side end of the pipe, so that a thickness at the third point far from the side end of the pipe is thick, and a thickness at the fourth point close to the side end of the pipe is thin;

(S 120 - 4 ) cutting the outer wall of the pipe which went through the step (S 120 - 3 ) from the fourth point close to the side end of the pipe to the side end of the pipe, so that a thickness is constant from the fourth point close to the side end of the pipe to the side end of the pipe;

(S 120 - 5 ) vertically cutting the side end of the pipe which went through the step (S 120 - 4 ) by a predetermined thickness;

(S 120 - 6 ) cutting the inner wall of the pipe which went through the step (S 120 - 5 ) from the side end of the pipe to a fifth point spaced apart from the side end of the pipe, so that a thickness is constant from the side end of the pipe to the fifth point spaced apart from the side end of the pipe; and

(S 120 - 7 ) slantly cutting the inner wall of the pipe which went through the step (S 120 - 6 ) from the fifth point close to the side end of the pipe to a sixth point far from the side end of the pipe, so that a thickness at the fifth point close to the side end of the pipe is thin, and a thickness at the sixth point far from the side end of the pipe is thick.

4. The weld groove forming method of claim 3 , wherein the step (S 120 - 1 ) is a step of cutting the outer wall of the pipe so that a thickness decreases at a constant rate from the first point to the second point,

wherein the step (S 120 - 2 ) is a step of cutting the outer wall of the pipe so that a thickness decreases at a constant rate from the second point to the third point,

wherein the step (S 120 - 3 ) is a step of cutting the outer wall of the pipe so that a thickness decrease according to a predetermined radius of curvature from the third point to the fourth point,

wherein the step (S 120 - 7 ) is a step of cutting the outer wall of the pipe so that a thickness increases at a constant rate from the fifth point to the sixth point.

5. The weld groove forming method of claim 3 , wherein the step (S 120 - 4 ) is a step of cutting the outer wall of the pipe so that a horizontal distance from the fourth point to the side end of the pipe is about 2 mm to 3 mm.

6. The weld groove forming method of claim 3 , wherein the step (S 120 - 5 ) is a step of cutting the outer wall of the pipe so that a thickness between the inner wall and the outer wall is about 1 mm to 2 mm.

7. The weld groove forming method of claim 3 , wherein the first point is positioned far from the side end of the pipe than the sixth point, and the second point is positioned close to the side end of the pipe than the fifth point.

8. The weld groove forming method of claim 7 , wherein the steps (S 120 - 1 ) to (S 120 - 7 ) are configured to cut the outer wall of the pipe so that a thickness between the inner wall and the outer wall of the pipe at the second point is 87.5% to 95% with respect to 100% of the thickness between the inner wall and the outer wall of the pipe at the first point.

9. The weld groove forming method of claim 1 , wherein the method further comprises (S 130 ) scanning the weld groove formed in the step (S 120 ) to determine circularity by using the sensor robot.

10. The weld groove forming method of claim 1 , wherein, the weld groove forming method further comprises:

(S 210 ) determining whether a side end of a hollow connection member is configured to be processed into a form of a true circle by using a sensor robot; and

(S 220 ) forming a weld groove in a form of a true circle at the side end of the hollow connection member by using an automatic beveling machine, when the sensor robot determines that the side end of the hollow connection member is configured to be processed into a form of a true circle in the step (S 210 ).

11. The weld groove forming method of claim 10 , wherein the step (S 110 ), the step (S 120 ), the step (S 210 ), and the step (S 220 ) are automatically performed.