Method for controlling overlapping of laser cladding, and method and system for dynamically adjusting height of laser head

1. A method for controlling overlapping in single-layer laser cladding of a shaft-like workpiece, comprising:

(1) acquiring a shaft diameter of the shaft-like workpiece to be processed, a feed rate of a feed shaft and a laser cladding width to obtain a calculation formula of an overlapping rate; and planning a motion of the feed shaft and a motion of a spindle based on a rotational velocity of the spindle and an S-curve acceleration and deceleration planning algorithm; and calculating a feed velocity of the feed shaft to obtain an acceleration time of the spindle and an acceleration time of the feed shaft;

(2) determining whether the acceleration time of the spindle is equal to the acceleration time of the feed shaft; if yes, calculating a displacement of the feed shaft and proceeding to step (4); otherwise, determining whether the acceleration time of the spindle is greater than the acceleration time of the feed shaft; if yes, after the feed shaft is accelerated to a preset velocity, keeping the feed shaft at the preset velocity until the spindle reaches the preset velocity; otherwise, proceeding to step (3);

(3) re-planning the motion of the spindle according to S-curve acceleration and deceleration; adding a period of uniform acceleration motion for the spindle or reducing a maximum jerk of the spindle to make the acceleration time of the spindle equal to the acceleration time of the feed shaft; calculating a total displacement of the feed shaft and proceeding to step (4); and

(4) adjusting an initial zero position of a laser head in a feed direction according to a difference between the total displacement of the feed shaft and a preset clamping allowance.

2. The method of claim 1 , wherein the calculation formula of the overlapping rate is derived by using a geometric method, and according to known processing conditions, the feed velocity f v of the feed shaft is calculated as follows:

f

v

=

π

⁢

⁢

dD

⁡

(

1

-

p

)

π

2

⁢

d

2

-

D

2

⁡

(

1

-

p

)

2

;

wherein d (mm) is the shaft diameter of the shaft-like workpiece to be processed; p is the overlapping rate; and D (mm) is the laser cladding width.

3. The method of claim 1 , wherein in S-curve acceleration and deceleration planning, when the acceleration time of the spindle is less than the acceleration time of the feed shaft, the motion of the spindle is re-planned according to an acceleration triangle planning method to make the spindle and the feed shaft reach their respective preset velocities through the same motion time; when a newly planned feed velocity of the spindle is greater than the preset velocity of the spindle, the maximum jerk of the spindle is reduced to make the newly planned feed velocity of the spindle equal to the preset velocity of the spindle; when the newly planned feed velocity of the feed shaft is lower than the preset velocity of the feed shaft, a period of uniform acceleration motion of the spindle is added to make the newly planned feed velocity of the spindle equal to the preset velocity of the spindle.

4. The method of claim 1 , wherein in S-curve acceleration and deceleration planning, an acceleration process comprises a stage in which an acceleration is increasing, a stage in which an acceleration is constant and a stage in which an acceleration is decreasing; a deceleration process comprises a stage in which a deceleration is increasing, a stage in which a deceleration is constant and a stage in which a deceleration is decreasing; for the spindle and the feed shaft, there is a uniform motion stage between the acceleration process and the deceleration process; and a whole motion process has seven stages.

5. The method of claim 4 , wherein the S-curve acceleration and deceleration planning comprises a seven-stage cubic spline function to enable continuous changes of accelerations of the spindle and feed shaft during the acceleration process and the deceleration process.

6. A method for controlling overlapping in single-layer laser cladding of a shaft-like workpiece, comprising:

(1) acquiring a shaft diameter of the shaft-like workpiece to be processed, a feed rate of a feed shaft and a laser cladding width to obtain a calculation formula of an overlapping rate; and planning a motion of the feed shaft and a motion of a spindle based on a rotational velocity of the spindle and an S-curve acceleration and deceleration planning algorithm; and calculating a feed velocity of the feed shaft to obtain an acceleration time of the spindle and an acceleration time of the feed shaft;

(2) determining whether the acceleration time of the spindle is equal to the acceleration time of the feed shaft; if yes, calculating a displacement of the feed shaft and proceeding to step (4); otherwise, determining whether the acceleration time of the spindle is greater than the acceleration time of the feed shaft; if yes, re-planning the motion of the feed shaft according to a triangular acceleration planning method;

adding a period of uniform acceleration motion for the feed shaft or reducing a maximum jerk of the feed shaft to make the acceleration time of the spindle equal to the acceleration time of the feed shaft; and calculating a total displacement of the feed shaft; otherwise, proceeding to step (3);

(3) re-planning the motion of the spindle according to S-curve acceleration and deceleration; adding a period of uniform acceleration motion for the spindle or reducing a maximum jerk of the spindle to make the acceleration time of the spindle equal to the acceleration time of the feed shaft; calculating the total displacement of the feed shaft and proceeding to step (4); and

(4) adjusting an initial zero position of a laser head in a feed direction according to a difference between the total displacement of the feed shaft and a preset clamping allowance.

7. The method of claim 6 , wherein in S-curve acceleration and deceleration planning, when the acceleration time of the spindle is greater than the acceleration time of the feed shaft, the motion of the feed shaft is re-planned according to the triangular acceleration planning method to make the spindle and the feed shaft reach their respective preset velocities through the same motion time; when a newly planned feed velocity of the feed shaft is greater than the preset velocity of the feed shaft, the maximum jerk of the feed shaft is reduced to make the newly planned feed velocity of the feed shaft equal to the preset velocity of the feed shaft; when the newly planned feed velocity of the feed shaft is lower than the preset velocity of the feed shaft, a period of uniform acceleration motion is added for the feed shaft to make the newly planned feed velocity of the feed shaft equal to the preset velocity of the feed shaft.