CN112756797A - High-precision laser engraving method - Google Patents

Abstract

The invention relates to a laser engraving method, in particular to a high-precision laser engraving method. The problems of uneven processing depth and the influence of the response time of light emitting and light shutting of a laser on the size of a part in the traditional laser engraving process are solved. In the invention, the acceleration and deceleration time of the loading platform and the response time of the laser and the IO module are considered in advance during path planning, and the deceleration track, the light-out and light-off response track are added on the original path, so that the depth uniformity of a product processed according to the updated path is good, the problems of deep processing depth of a starting point and a finishing point and poor processing quality caused by too high pulse overlapping rate are solved, and the size processing precision is improved by considering the response time of the laser and the IO module. The method is particularly suitable for irregular figure engraving process.

Description

High-precision laser engraving method

Technical Field

The invention relates to a laser engraving method, in particular to a high-precision laser engraving method.

Background

With the rapid development of the photoelectric technology, the application range of the laser processing technology is wider and wider, and the requirement on the processing precision is higher and higher.

The laser engraving work principle is that a high-energy laser beam is irradiated on the surface of a material, a small part of laser is reflected, most of light passes through the surface of the material and is converted into heat energy in the material to heat the material, and due to the heat effect of the material, the material is irradiated by the laser beam with sufficient power density to reach the melting and vaporizing temperature of the surface of the material, so that the material is vaporized or melted, and a required target pattern is formed.

In the traditional laser engraving process, firstly, an engraving path is generated according to a target pattern, and then, the carrying platform is controlled to move according to the engraving path, so that the laser is ensured to be filled in an engraving area. As shown in fig. 1, the engraving of a certain path is completed at times T1 to T4. At the time from T1 to T2, the loading platform accelerates to the laser engraving speed; at the time of T2-T3, the platform moves at a constant speed at the laser engraving speed; t3 to T4, the stage decelerates from the laser engraving speed to a stop. At the time from T1 to T2, the movement speed of the platform is slow, and the laser engraving speed is not reached, so that the laser overlapping rate is high, and the processing depth is deep at the time; at the time from T2 to T3, the platform moves at a constant speed at the laser engraving speed, so that the processing depth is kept consistent at the time; at the time T3 to T4, the platform decelerates, the laser overlapping rate is high, and more material is removed, so that the processing depth is deeper in the period of time. Therefore, the processing depth of the start point and the end point is larger than the target processing depth throughout the processing time from T1 to T4, resulting in lower depth accuracy.

Referring to fig. 2, when an irregular groove needs to be machined on the surface of a product, a machining path is directly generated according to the peripheral outline of an irregular groove pattern when a conventional laser engraving method is used for generating the machining path for general-purpose CAM software. The loading platform moves according to the processing path, and the dotted line in fig. 2 is the moving track of the loading platform. One of the dashed lines can be taken as an example to illustrate that: when the initial position of the dotted line is processed, the loading platform is in accelerated motion at the moment and does not reach the laser engraving speed, so that at the initial position, more materials are removed due to high laser overlapping rate, and the processing depth is deeper. Similarly, at the position close to the end point, the loading platform is in deceleration motion, the laser overlapping rate is high, and the removed material is more, so that the processing depth is deeper, and the depth of the final processed pattern is not uniform. Laser light switching on and off also has an influence on processing precision, response time of laser light emitting and light switching off can influence the size of a processed part, light switching on later can cause the size of the part to be reduced, and light switching on earlier can cause the size of the part to be increased.

Disclosure of Invention

In order to solve the problems of uneven processing depth and influence of laser light emitting and light closing response time on the size of a part in the traditional laser engraving process, the invention provides a novel laser engraving method, wherein a theoretical processing path is adjusted according to processing parameters to obtain an actual processing path, so that the processing depth on the whole processing path is equal, higher processing precision is obtained, and the influence of the laser light emitting and light closing response time on the size of the part is eliminated.

The technical scheme of the invention is to provide a high-precision laser engraving method which is characterized by comprising the following steps:

step 1, importing a carved pattern Dxf file;

step 2, setting processing parameters, wherein the processing parameters comprise: laser engraving speed, laser power, repetition frequency, laser on-off response time, filling distance, loading platform acceleration and loading platform deceleration;

step 3, generating a theoretical machining path according to the Dxf file, calculating an actual machining path by combining the theoretical machining path and machining parameters, and further generating a machining G code according to the actual machining path;

a. determining the light-emitting position N of a laser₁；

N₁A₁＝Vt₂

Wherein A is₁Is the starting position of the region to be processed, N₁At A₁Before position, V is laser engraving speed, t₂The laser light-on response time;

b. determining the starting position of the loading platform;

P₀P₁＝1/2at²；

wherein, P₀The position being the starting position of the carrier platform, P₁The position is located at a laser light-emitting position N₁Before, P₀After the position, a is the acceleration of the objective platform, t is V/a, and V is the laser engraving speed;

c. determining laser off position N₂；

N₂A₂＝Vt₃

Wherein A is₂As the end position of the region to be processed, N₂At A₂Before position, V is laser engraving speed, t₃The laser turn-off response time;

step 4, starting processing;

in the processing process, aiming at different processing paths, the starting position, the laser light emitting position and the laser light closing position of the loading platform are updated in real time.

The invention has the beneficial effects that:

in the invention, the acceleration and deceleration time of the loading platform and the response time of the laser and the IO module are considered in advance during path planning, and the deceleration track, the light-out and light-off response track are added on the original path, so that the depth uniformity of a product processed according to the updated path is good, the problems of deep processing depth of a starting point and a finishing point and poor processing quality caused by too high pulse overlapping rate are solved, and the size processing precision is improved by considering the response time of the laser and the IO module. The method is particularly suitable for irregular figure engraving process.

Drawings

FIG. 1 is a diagram of engraving time versus the operating speed of a loading platform in a conventional laser engraving process;

FIG. 2 is a diagram of a process path generated by a conventional laser engraving process;

FIG. 3 is a schematic view of an actual processing path identified by the present invention;

FIG. 4 is a schematic view of an actual machining path for machining an irregular groove according to the present invention;

fig. 5 is a schematic view showing a positional relationship between each position point in an actual machining path when the irregular groove is machined according to the present invention.

Detailed Description

The invention is further described with reference to the following figures and specific embodiments.

As shown in FIG. 3, assume that the area to be processed is A₁、A₂The straight line area between the two parts, the carving path generated by the traditional path planning software leads the carrying platform to be driven from A₁Starting the operation to A₂Stopping the point; the laser light emits from point A1, A₂The light is turned off. However, when the loading platform is started, the laser engraving speed can be reached only by a period of time of acceleration, and the existence of the response time of the laser switch light causes that the laser engraving speed is A₁And A₂The depth of the spot machining is greater than the target machining depth.

The invention improves the traditional path planning software to generate the carving path, so that the loading platform is positioned at A₁P before position₀Starting at a position, P₀The position of the points needs to ensure that: when the loading platform moves to N₁Before the point, the speed reaches the laser engraving speed; so that at N₁At the position, the laser emits light; so that at N₂At the position, the laser is off; so that the loading platform moves to A₂When in position, the operation of the carrying platform is stopped, and the carrying platform is decelerated to a certain distance to P₂And when the position is reached, the operation is completely stopped.

In FIG. 3, N₁The point corresponds to the light-emitting position of the laser, and the light-emitting position can be calculated according to the light-on response time of the laser, wherein the laser is positioned at N₁The point emits light, and the loading platform just runs to A₁At this time, is at A₁And A₂When the movement reaches N, the constant speed movement is carried out₂The laser is turned off when the position is in the position, and when the laser stops emitting light, the loading platform just runs to A₂At this point, the platform is slowed down to P2.

The method of the invention is used for processing the pattern in the figure 4, and comprises the following steps:

1) importing an engraving pattern Dxf file;

2) setting processing parameters, wherein the processing parameters mainly comprise: laser engraving speed, laser power, repetition frequency, laser on-off response time, filling distance, loading platform acceleration and loading platform deceleration;

3) generating a theoretical machining path according to the Dxf file, calculating an actual machining path by combining the theoretical machining path and machining parameters, and further generating a corresponding machining G code according to each actual machining path;

the following data need to be determined when calculating the actual machining path:

a. determining the starting position of the loading platform;

when determining how far away from the starting position of the theoretical machining path, starting the loading platform, namely determining the position of P0 in FIG. 5; the position of P0 is required to satisfy: so that the stage reaches the position N1, where N1 is located before the position a1, the speed has been accelerated to the laser engraving speed.

In the figure P₀P₁The stage is an acceleration stage, P₁A₁The segment is a constant speed segment, and P is calculated by the following formula₀P₁Length of the segment:

t＝V/a；P₀P₁＝1/2*a*t²

wherein a is the acceleration of the loading platform, and V is the set laser engraving speed, which are all known conditions. Thus P can be calculated₀P₁The length of the segment.

b. Determining a laser light emitting position;

the laser is turned on, i.e. the position of N1 in fig. 5, determining how far from the starting position of the theoretical machining path.

P₁N₁The loading platform in the section moves at a constant speed at the laser engraving speed and is set to be a constant speed stage through CAM software. N is a radical of₁A₁In between is a light-on phase, N₁The laser light is triggered by IO, but because the laser and the IO time delay laser are really in A₁The delay time of the laser and IO can be defined as the laser light-on delay time t₂. Thus, N₁A₁＝V*t₂。

c. Determining a laser light-off position;

the laser is turned off, i.e. the position N2 in fig. 5, when determining how far from the end position of the theoretical machining path.

N₂A₂For laser light-off distance, laserIts device is in N₂Is closed but will be at A due to delay₂Is actually closed and point a2 is just the end of process position. Let the laser turn-off response time be t₃Then N is₂A₂＝Vt₃，A₂P₂＝1/2*a*t₃ ²。

4: starting processing;

fig. 4 and 5 show the planned path generated by the method of the present invention, where P0 is the starting position of the stage, P1 is the speed of the stage added to the set value, i.e., the laser engraving speed, P2 is the stopping position of the stage, the horizontal line in the diagram is the stage travel path, the dark color point is the laser on position, and the light color point is the laser off position.

In the processing process, aiming at different processing paths, the starting position, the laser light emitting position and the laser light closing position of the loading platform are updated in real time.

As can be seen from the figure, the running speed of the platform is uniform in the area needing to be engraved, and the depth consistency of the processing groove is better.

Claims (1)

1. A high-precision laser engraving method is characterized by comprising the following steps:

step 1, importing a carved pattern Dxf file;

step 2, setting processing parameters, wherein the processing parameters comprise: laser engraving speed, laser power, repetition frequency, laser on-off response time, filling distance, loading platform acceleration and loading platform deceleration;

step 3, generating a theoretical machining path according to the Dxf file, calculating an actual machining path by combining the theoretical machining path and machining parameters, and further generating a machining G code according to the actual machining path;

a. determining the light-emitting position N of a laser₁；

N₁A₁＝Vt₂

Wherein A is₁Is the starting position of the region to be processed, N₁At A₁Before position, V is laser engraving speed, t₂For laser soundingThe reaction time;

b. determining the starting position of the loading platform;

P₀P₁＝1/2at²；

wherein, P₀The position being the starting position of the carrier platform, P₁The position is located at a laser light-emitting position N₁Before, P₀After the position, a is the acceleration of the objective platform, t is V/a, and V is the laser engraving speed;

c. determining laser off position N₂；

N₂A₂＝Vt₃

Wherein A is₂As the end position of the region to be processed, N₂At A₂Before position, V is laser engraving speed, t₃The laser turn-off response time;

step 4, starting processing;

in the processing process, aiming at different processing paths, the starting position, the laser light emitting position and the laser light closing position of the loading platform are updated in real time.

Images