JP2024508104A - Laser temperature control method and machining equipment - Google Patents

Abstract

First, the target operating temperature of the refrigerant is roughly adjusted in real time according to the change in the heat load of the laser, and the target operating temperature of the refrigerant is finely adjusted in real time based on the temperature change of the laser itself using PID control. A laser temperature control method is provided in which the target operating temperature of a refrigerant is roughly and finely adjusted, and at the same time, the actual temperature of the refrigerant is kept close to the target operating temperature by PID algorithm control. The method of the present invention greatly improves the stability and responsiveness of the laser operating temperature and avoids the "false stability" phenomenon where the laser temperature is unstable while the water cooler temperature is stable. . Dynamically adjusts the cooling capacity according to the output power of the laser, ensuring that the maximum variation range of the laser temperature is less than ±0.25℃ when the laser operates in the operating range from zero to full power . [Selection diagram] Figure 4

Description

The present invention relates to a method for controlling temperature, and particularly to a method for notifying laser temperature that facilitates precision laser processing and improves processing accuracy.

Lasers, especially pulsed lasers, are widely applied in industrial production. Due to their characteristics, lasers emit a large amount of heat during operation, and generally the operating temperature range of lasers is ±5 to 10°C, but in reality Since the amount of heat (temperature) generated by lasers under operating conditions is far beyond this range, precise and constant control of temperature has become one of the technical obstacles for laser applications.

Water coolers are a widely used cooling mechanism and are often used for constant temperature control of lasers. The laser is pre-installed with a water cooling connector for convenient connection by the user to a cooling device such as a water cooler.

Generally, a water cooler uses cooling water/cooling fluid as a refrigerant, and the low-temperature water that comes out of it flows through the internal circulation line of the laser, returns to the water cooler after removing heat, and then returns to the water cooler. monitors the temperature of the reflux water, adjusts the cooling capacity, and stabilizes the temperature of the hot reflux water around the set temperature. For general laser processing applications, the above configuration is sufficient, ie, when the laser is operating, its temperature is always controlled within an operating range of less than ±5°C.

Precision laser processing differs from general laser applications in the following points. 1) In precision laser processing, it is necessary to control the frequency and energy of the laser in real time, and the output power of the laser changes constantly, and its heat generation value changes constantly, that is, the heat load changes, but The laser for precision laser processing only has a switching function, has only one output power, and its calorific value does not change, that is, it is a constant heat load; 2) The processing accuracy requirements of precision laser processing are , at the micron to nanometer level, and slight temperature changes in the laser have a large impact on processing accuracy, resulting in processing errors. Generally, processing requirements for laser processing are at the millimeter level, and temperature changes of the laser do not have a large effect on processing accuracy and are within the allowable range of processing errors.

Therefore, the current general laser cooling system has the following problems when applied to precision laser processing. 1) When the output power of the laser changes, the operating temperature of the laser cannot be kept constant and fluctuates within the range of at least 3-5℃, which is due to the fact that the temperature control has a typical delay It is a control system, and the amount of heat generated changes instantly due to changes in laser power, and this change in amount of heat takes time until the temperature of the intercooler increases and is detected by the water cooler. If the water cooler adjusts its cooling power based on the sensed temperature change, the laser's output power has already changed (multiple times), and in this way the water cooler's cooling power coordinates with the laser power. This results in oscillation of proportional-integral-derivative (PID) parameters. Similarly, for the same reason as above, even if the laser power remains unchanged, control of the temperature to equilibrium is relatively slow, typically taking 5 minutes or more.

In summary, typical laser cooling systems used in precision laser machining distort the constant temperature of the water cooler, and the rate and amplitude of the laser's temperature change are both significantly greater than the changes sensed by the water cooler's sensors. This is extremely disadvantageous to the stability of precision laser processing and the realization of high-precision processing.

One object of the present invention is to provide a laser temperature control method that maintains the actual temperature of the laser in operating conditions within an operating range of less than ±1° C. to improve laser processing accuracy.

Another object of the present invention is to provide a laser temperature control method that coordinates the cooling power of the water cooler and the operating power of the laser with each other, reduces the oscillation amplitude of the PID parameter, and maintains the laser temperature constant. be.

Another object of the present invention is to provide a laser temperature control device that coordinates the cooling power of a water cooler and the operating power of a laser, avoids delays in laser temperature control, and is suitable for precision laser processing. It is.

Yet another object of the present invention is to provide a machining device that performs precision laser machining.

By monitoring the heat load of the laser, the method of the present invention dynamically adjusts the coolant temperature in real time based on the change in the heat load of the laser, so that the laser has a constant temperature effect even under different heat loads. Realize. That is, the target operating temperature of the refrigerant is first roughly adjusted in real time according to changes in the heat load of the laser, and then the target operating temperature of the refrigerant is finely adjusted in real time based on the temperature change of the laser itself using PID control. At the same time, the target operating temperature of the refrigerant is roughly adjusted and finely adjusted, and at the same time, the actual temperature of the refrigerant is kept close to the target operating temperature using PID algorithm control.

The method of the present invention adopts a dual PID control system consisting of PID control of constant temperature target temperature and cooling PID control of the cooler itself, greatly reducing system coupling, and monitoring of laser power is It may also be monitoring of laser control commands, both of which have the same effect.

The laser temperature control method is
The heat load detection module and temperature detection module detect the real-time heat load and real-time temperature of the laser, respectively, and when the output power of the laser changes, the pre-programmed set temperature can be set to match the current power of the laser. Set the cooling target operating temperature of the cooler;
The temperature detection module continuously detects the laser, obtains the temperature change curve, and dynamically changes the refrigerant target operating temperature of the cooler based on the pre-programmed PID control parameters, and the cooler is constantly updated. adjusting the refrigerant temperature based on the refrigerant target operating temperature and an internal PID algorithm;
including.

A specific implementation method of the method of the present invention monitors the heat load and temperature of the laser through a control system (including a power detection module and a temperature detection module), and adjusts the coolant target operating temperature of the cooler based on the heat load. Then, taking the laser temperature as a reference and finely adjusting the target operating temperature of the cooler based on the laser PID algorithm, that is, if the current real-time temperature of the laser is higher than the constant target temperature of the laser, the cooler's target operating temperature is finely adjusted based on the laser PID algorithm. Decrease the cooling target operating temperature, if the current real-time temperature of the laser is lower than the laser constantization target temperature, increase the coolant target operating temperature of the cooler, so that the PID increases the current actual temperature of the laser and the constantization target temperature of the laser. The height of the refrigerant target operating temperature is determined according to the situation of the target temperature deviation.

The cooler maintains the temperature of the refrigerant at the refrigerant target operating temperature based on its cooling PID algorithm, i.e., if the current actual temperature of the refrigerant is higher than the target operating temperature of the refrigerant, it cools and the refrigerant's current If the actual temperature of the refrigerant is lower than the refrigerant target operating temperature, it will stop heating or cooling, and the cooler PID will adjust the magnitude of the cooling power according to the situation of the deviation between the current actual temperature of the refrigerant and the refrigerant target operating temperature. Determine.

In the method of the invention, the thermal load detection module is to be understood as a device for obtaining the output power of the laser, or a software module for obtaining the output power value, or a combination of a device and a software module.

In the method of the invention, the temperature detection module is to be understood as a device for obtaining the real-time temperature of the laser, or a software module for obtaining the real-time temperature value, or a combination of a device and a software module.

In the method of the present invention, the temperatures of the laser body and the laser head are controlled independently.

The method of the present invention greatly improves the stability and responsiveness of the laser operating temperature and avoids the "false stability" phenomenon where the laser temperature is unstable while the water cooler temperature is stable. . Dynamically adjusts the cooling capacity according to the laser output power, ensuring that the maximum variation range of laser temperature is less than ±0.25℃ when the laser operates in the operating range from zero to full power. Ru. At the same time, the temperature control responsiveness of the laser is greatly improved, and when the laser output is stable at a constant power, the laser temperature can be controlled within ±0.1° C. within 180 seconds.

In order to carry out the above method, the present invention comprises:
a temperature detection module used to obtain real-time temperature data of the laser, such as the internal temperature of the laser head and the internal temperature of the laser body;
a thermal load detection module used to obtain the relevant data of the real-time thermal load of the laser, such as input/output voltage, input/output current and input/output power;
A cooler including an intermediate cooling mechanism, a cooling mechanism, a PID electric control mechanism, etc.;
A master controller including a programmable controller such as an industrial PC or an embedded controller and a communication module;
Equipped with.

The heat load detection module and the temperature detection module provide the acquired data to the master controller, and the master controller adjusts the cooling target temperature of the cooler based on the measured data.

The intercooling mechanism of the device of the invention includes refrigerant, monitoring and circulation pumping mechanisms (circulation pumps, lines and flow sensors, etc.).

The cooling mechanism of the device of the present invention includes a cooling member (semiconductor cooling chip, compressor, etc.) and a heat exchange device (heat exchange sheet, heat exchange copper tube, etc.).

The PID electrical control mechanism of the device of the invention includes a controller (such as an embedded controller, a programmable controller and a temperature sensor) and a power supply.

In the device of the present invention, the master controller simultaneously monitors the laser main body and the laser head, and the laser main body and the laser head are each equipped with a cooler to independently adjust and control the temperature.

A machining device employing the method of the present invention or the device of the present invention realizes precision laser machining.

FIG. 3 is a diagram of the temperature change of a laser whose temperature is controlled using a constant frequency water cooler. FIG. 3 is a diagram of the temperature change of a laser whose temperature is controlled using a constant frequency water cooler. FIG. 3 is a diagram of the temperature variation of a laser whose temperature is controlled using a semiconductor water cooler. FIG. 3 is a diagram of the temperature change of a laser whose temperature is controlled by the method of the present invention. FIG. 1 is an explanatory diagram of an embodiment of an apparatus for carrying out the method of the present invention to control temperature.

In the following, the technical solution of the present invention will be explained in detail together with the drawings. The embodiments of the present invention are intended to illustrate the technical solution of the present invention, but not to limit it. Although the present invention will be described in detail with reference to the preferred embodiments, as those skilled in the art will understand, the technical solution of the invention can be modified or equivalently replaced, and the technical solution of the present invention The invention should be included in the claims of the present invention without departing from the spirit and scope of the invention.

A picosecond laser with a maximum heat output of 300 watts is used as the laser light source, and a constant frequency cooler for the laser (cooling capacity 1.5Kw, set target temperature 22℃, non-PID temperature control, temperature control range ±0.1℃), for the laser A variable frequency water cooler (cooling capacity 0.6Kw, set target temperature 22℃, PID temperature control) and a semiconductor water cooler for laser (cooling capacity 0.6Kw, set target temperature 22℃, PID temperature control) are installed. Configure the laser temperature control plan, and when the room temperature is 25°C and the set water temperature is 22°C, the laser outputs continuously for 30 minutes at each power from 25% output power to 100% output power, and then switches. Finally, the power was returned to 25% and output for 30 minutes to consider the temperature control adjustment ability of the cooling system, and the results are shown in Table 1 below.

From the above, it can be seen that when laser cooling is applied to a conventional water cooler, the fluctuation range of the laser is about 3° C. or more, and the need for precision laser processing cannot be met.

A picosecond laser with a maximum output of 300 watts is used as a laser light source, a cooler (cooling capacity 0.6 Kw, set target temperature 22°C, PID temperature control) and the method of this embodiment are adopted, that is, a control system (power detector monitor the laser's heat load and temperature through the laser's temperature detector), adjust the cooling target temperature based on the significant adjustment of the heat load, and adjust the cooling target temperature based on the laser's temperature and the laser PID algorithm. finely adjust the cooling target temperature of the laser, i.e., when the laser temperature is higher than the cooling target temperature, lower the lake town set temperature, and when the laser temperature is lower than the cooling target temperature, reduce the cooler set temperature. The PID determines the magnitude of the set temperature based on the degree of temperature deviation.

The cooler maintains the temperature of the coolant at the set temperature based on its cooling PID algorithm, that is, it cools when the coolant temperature is higher than the set temperature, and heats when the coolant temperature is lower than the set temperature. , the cooler PID determines the amount of cooling power based on the degree of temperature deviation.

To implement the method of this embodiment, the apparatus shown in FIG. 5 can be used to control the temperature of the laser, which apparatus includes:

The temperature detection module 100 is used to obtain real-time temperature data of the laser 500, such as the internal temperature of the laser head and the internal temperature of the laser body.

The thermal load detection module 200 is used to obtain real-time thermal load related data of the laser, such as input/output voltage, input/output current, and input/output power.

The cooler 300 includes an intermediate cooling mechanism, a cooling mechanism, a PID electric control mechanism, and the like.

Master controller 400 includes a programmable controller, such as an industrial PC or an embedded controller, and a communication module.

The cooling mechanism includes a refrigerant 600, a monitoring and circulation pump mechanism, etc., and the refrigerant 600 flows within the cooler 300 and the laser 500.

The heat load detection module and the temperature detection module provide the acquired data to the master controller, and the master controller adjusts the cooling target temperature of the cooler based on the measured data.

The state of the temperature change of the obtained laser is shown in FIG. 4, and the degree of temperature fluctuation in all stages is ±0.2°C, and the degree of temperature fluctuation in the stable output stage (after 10 minutes of output) is ±0. It is 1℃. Compared with Table 1, the temperature variation in all stages is significantly reduced, and the temperature variation in the stable output stage is only ±0.1°C, making the temperature of the laser more constant.

The method and apparatus of this embodiment can meet the needs of precision laser processing after being applied to a machining device.

100 Temperature detection module 200 Heat load detection module 300 Cooler 400 Master controller 500 Laser 600 Refrigerant

Claims (5)

First, the target operating temperature of the refrigerant is roughly adjusted in real time according to the change in the heat load of the laser, and the target operating temperature of the refrigerant is finely adjusted in real time based on the temperature change of the laser itself using PID control. A laser temperature control method characterized by roughly and finely adjusting a target operating temperature of a refrigerant, and at the same time keeping the actual temperature of the refrigerant close to the target operating temperature by PID algorithm control. The heat load of the laser is monitored, and the target operating temperature of the coolant is roughly adjusted in real time according to the change in the heat load of the laser, and the target operating temperature of the coolant is adjusted based on the temperature change of the laser itself using PID control. Dual PID control is achieved by finely adjusting the temperature in real time, roughly and finely adjusting the target operating temperature of the refrigerant, and at the same time keeping the actual temperature of the refrigerant close to the target operating temperature using PID algorithm control. configuring the system and reducing system coupling, characterized in that the monitoring of the thermal load of the laser may be monitoring of the thermal load of the laser, and may be the monitoring of a control command that adjusts the thermal load of the laser. The laser temperature control method according to claim 1. Heat load monitoring and laser temperature monitoring measure the real-time heat load and real-time temperature of the laser, respectively, and adapt to the pre-programmed current heat load of the laser when a change in the laser heat load occurs. The temperature detection module continuously detects the laser, obtains the temperature change curve, and determines the refrigerant target operating temperature of the cooler based on the pre-programmed PID control parameters. 2. The method of claim 1, wherein the cooler adjusts the coolant temperature based on a continuously updated coolant target operating temperature and an internal PID algorithm. 2. The laser temperature control method according to claim 1, wherein independent temperature control is performed on the laser body and the laser head. A machining device comprising the laser temperature control method according to claim 1.

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