Patent Description:
In a laser system used to laser process a workpiece, for example by means of <NUM>-D printing or laser-welding, thermal dissipation may cause temperature variations of the components of the laser system and, ultimately, precision loss. For this reason, cooling systems are employed for providing thermal stability in order to prevent such losses of laser precision. Such cooling systems typically use a controlled flow of a cooling fluid, mostly water or air. Thermal stability is then provided by controlling the temperature and/or flowing conditions of the cooling fluid.

The cooling power of the cooling system is determined by the difference between the temperature of the components to be cooled and the cooling fluid, as well as by the flow conditions of the cooling fluid, in particular of the flow velocity and quantity thereof. The temperature and/or flowing conditions of the cooling fluid are typically kept constant.

In laser processes in which energy use conditions may be timely variable, for example due to the alternation of activity times with pause times, thermal equilibrium in the laser system may be broken due to different thermal conditions. A varying energetic balance may cause the cooling system to have different cooling efficiencies and outcomes at different times, resulting in the uncontrolled absorption of heat by components of the laser system and hence in loss of laser precision.

Reactive protocols to adapt the cooling conditions after such losses of thermal equilibrium occur have limited effect, since there is always a thermal delay or shift between the action of the cooling system and actual thermal dissipation in the laser system.

Therefore, there is room for technical improvement in the field of cooling systems for laser processing devices and system.

A predictive cooling method for cooling a laser system based on a current applied to a laser light source is known from<CIT>.

The present invention aims at providing a solution to the previously mentioned disadvantages of the prior art by providing a cooling control unit, a laser system and a method allowing to implement a predictive cooling scheme for a laser processing device. A solution to this problem is provided by a cooling control unit according to claim <NUM>, by a laser system according to claim <NUM> and by a method according to claim <NUM>.

A first aspect of the invention refers to a cooling control unit for controlling a cooling system of a laser processing device. "Laser processing device" may refer herein to a device configured for laser-processing a workpiece, for example by a <NUM>-D printing, laser-welding, laser-cutting, laser-graving, laser-marking or any other laser process. The laser processing device may for example be or comprise an additive manufacturing module, a welding module, or a <NUM>-D printer. For this purpose, the laser processing device comprises a deflection unit for controllably deflecting a laser beam to a target point in space, in particular to a target point on a work field of the laser processing device. Such deflection unit may comprise one or more movable mirrors. For example, the deflection unit may comprise a first movable mirror rotatable around a first axis and a second movable mirror rotatable around a second axis perpendicular to the first axis, i.e. a so-called pair of XY movable mirrors. The deflection unit operates on electric energy. Electric energy is used for driving a movement of the movable mirrors, which electric energy need to be fed into the deflection unit for operation.

The laser processing device may further comprise a laser light generation device for generating a laser beam for laser-processing said workpiece. The laser light source also operates on electric energy, used for generating the laser beam. The laser light generation device may comprise a laser light source. However, the laser light generation device may additionally or alternatively comprise one or more components for providing a laser beam from laser light provided by an external source. For example, the laser light generation device may be or comprise a collimator. The cooling control unit according to the invention may be hardware-implemented and/or software-implemented. For example, the control unit may be a dedicated processing unit and/or a dedicated module within a processing unit, such as a CPU, a control card or the like. As a further example, the cooling control unit may be a piece of software implementable on such a processing unit or on a general-purpose computer.

The cooling control unit according to the invention comprises a measurement module and a regulation module. The measurement module is configured for detecting a parameter of an electric power input provided to the laser processing device and for determining whether the parameter is varying, in particular increasing or decreasing, possibly by a at least given predefined difference, for example by <NUM>% or more, <NUM>% or more or <NUM>% or more. The parameter may be considered to be varying if such predefined difference is registered over a predefined time interval, for example over a time interval of <NUM> minute or <NUM> second. The "electric power input" refers herein to an input receivable by the laser deflection unit of the laser processing unit, , that correlates with an electric energy consumption of the laser processing unit.

In a first variant of the invention, the electric power input corresponds to an electric current fed into the deflection unit of the laser processing module for providing electric energy on which the deflection unit operates.

In a second variant of the invention, the electric power input corresponds to an electric signal encoding a control command corresponding to an instruction to the laser deflection unit of the laser processing device or to another device connected thereto related to an electric power input provided to the laser deflection unit of the laser processing device. For example, the electric power input may correspond to an electric signal encoding a control command controlling properties of an electric current being provided to the laser deflection unit of the laser processing device and/or controlling an operation of the laser deflection unit of the laser processing device.

A "parameter" may refer herein to a measurable or detectable property of such electric power input. If the electric power input corresponds to an electric current, the parameter may be a measurable electric parameter, such as for example an electric current intensity, an electric voltage and/or an electric power. If the electric power input corresponds to a control command provided or to be provided to the laser processing device, the parameter may correspond to an instruction encoded in the control command, for example to a "raise electric power" instruction or to a "reduce electric current intensity" instruction.

The regulation module is configured for generating a control signal for controlling the cooling system based on the parameter detected by the measurement module to vary a cooling power of the cooling system if the measurement module determines that the parameter is varying. In particular, the regulation module may be configured for generating the control signal for controlling the cooling system based on the parameter detected by the measurement module to:.

The control signal generated by the regulation module of the cooling control unit according to the invention may be provided to a cooling system configured for providing a cooling effect to the laser processing device, in particular to the deflection unit and/or the laser light generation unit thereof. The control signal may for example correspond to an "increase cooling power" instruction or to a "decrease cooling power" instruction.

Thus, the cooling control unit according to the first aspect of the invention is specifically programmed to generate a control signal that allows selectively controlling the cooling conditions of a laser processing device based on a parameter of the electric power input. This is based on the realisation by the present inventors that a parameter of an electric power input, for example, an electric current intensity or an electric current voltage provided to the laser deflection unit of the laser processing device as a feeding of electric energy or a related control command, can be used as a reliable prediction of the cooling power that will be subsequently needed in the laser processing device to maintain thermal equilibrium, before or while thermal conditions actually vary.

If, for example, the deflection unit of the laser processing device must be moved quickly and repeatedly during a given phase of a laser process, this may require a higher input of electric power into the laser processing device. As a consequence, a control command to increase the electric power being input into the laser processing device, in particular to the deflection unit, may be generated and provided to the laser processing device and/or to an electric power supply connected thereto. The cooling control unit of the invention may detect this variation in the electric power input and correspondingly increase the cooling power of the cooling system, for example by correspondingly increasing a speed or decreasing a temperature of a cooling fluid, upon detecting the intended increase in electric power input or the corresponding control command, thereby preventively countering thermal instability in the laser processing device before or while it sets in.

As a consequence, the cooling power provided by the cooling system can be adapted to thermal conditions that are about to occur in the laser processing device and better thermal stability can be achieved as compared to a constant cooling scheme and to a reactive/corrective cooling scheme. Thereby, better laser quality can be provided.

Notably, the cooling control unit of the invention allows achieving a better control of thermal conditions in the laser processing device without requiring an additional temperature control circuit.

According to preferred embodiments, the measurement module may be further configured for detecting a value of the parameter. If, for example, the electric power input corresponds to an electric current being provided to the laser processing device, and the parameter corresponds to an electric current intensity, the value of the parameter may correspond to a current intensity value, for example <NUM> mA, which can be detected by the measurement module. The regulation module may be further configured for generating the control signal to control the cooling system to set the cooling power to a target cooling power value based on the parameter value according to a first predefined model. The first predefined model may map parameter values to target cooling power values. For example, the first predefined model may map a value of the parameter of <NUM> mA to corresponding first flow conditions of a cooling fluid implementable by the cooling system. Thus, by reference to the previous example, the control signal may be generated as a control signal specifically associated to a current intensity value of <NUM> mA. According to this example, the first predefined model may forecast that when an electric current with an electric current intensity that turns to <NUM> mA is provided to the laser processing device, the cooling system needs to provide said first flow conditions of the cooling fluid in order to maximise thermal stability in the laser processing device.

The first predefined model may be based on a linear relationship between the parameter of the electric power input and a temperature and/or flowing speed of the cooling fluid used by the cooling system for cooling the laser processing device. Such linear relationship may comprise a proportionality factor that can be determined experimentally or by means of simulation.

In related preferred embodiments of the invention, the measurement module may further be configured for detecting a variation rate of the parameter. A variation rate may refer herein to a variation per unit of time. For example, the measurement module may detect a variation in an electric current intensity of <NUM> mA/s. The regulation module may further be configured for generating the control signal to control the cooling system to set a variation rate of the cooling power to a target cooling power variation rate based on the variation rate of the parameter according to a second predefined model. The second predefined model may map variation rate of the parameter to target cooling power variation rates. For example, the second predefined model may map a variation rate of the parameter of -<NUM> mA/s to corresponding second flow conditions of a cooling fluid implementable by the cooling system. According to this example, the second predefined model forecast that when an electric current with an electric current intensity that is decreasing at a rate of <NUM> mA/s is provided to the laser processing device, the cooling system needs to provide said second flow conditions of the cooling fluid in order to maximise thermal stability in the laser processing device.

In preferred embodiments, the measurement module may be connected or connectable to an electric power supply device configured for providing an electric current to the laser deflection unit of the laser processing device. The electric power supply device may be an independent device, in particular a device different from the laser processing device. "Independent device" may refer herein to a structurally and/or functionally independent device. The measurement module may be configured for detecting an electric parameter of the electric current provided by the electric power supply device as said parameter. The electric parameter may preferably be an electric current intensity (measurable in Amperes or in subunits thereof) and/or an electric power (measurable in Watt or in subunits thereof). By detecting the parameter of the electric current provided by the electric power supply device, in particular by detecting variations thereof, the cooling control unit of the invention can correctly predict when it is necessary to adapt the cooling conditions provided by the cooling system in order to improve thermal stability of the laser processing device.

According to preferred embodiments, the measurement module may be connected or connectable to an internal control circuitry of the laser processing device configured for measuring an electric parameter of an electric current being input to the laser deflection unit of the laser processing device. The internal control circuitry may be a component of the laser processing device, in particular of the laser deflection unit. The internal control circuitry may be configured for measuring the electric parameter and the measurement module may be configured for obtaining the electric parameter from the internal control circuitry. The electric parameter may preferably be an electric current intensity and/or an electric power. The electric parameter corresponds to the parameter, the variation of which is detected by the measurement module. Thus, in laser processing devices including such internal control circuitry, the parameter used by the cooling control unit according to the present invention can be obtained from the internal control circuitry without employing any dedicated measurement equipment.

In some preferred embodiments, the measurement module may be connected or connectable to an electric sensor configured for measuring an electric parameter of an electric current being input to the laser deflection unit of the laser processing device a. The measurement module may be configured for detecting the electric parameter measured by the electric sensor. The electric sensor may be an independent device, in particular a device different from the laser processing device. "Independent device" may refer herein to a structurally and/or functionally independent device. The electric parameter may preferably be an electric current intensity and/or an electric power. The electric sensor may be an independent device, which may be or comprise a multimeter or the like. "Independent device" may refer herein to a structurally and/or functionally independent device. Thanks to the electric sensor, the cooling control unit according to the invention may be adapted to operate with a laser processing device, which may possibly not include an integrated internal control circuitry according to the previously described embodiment.

According to preferred embodiments, the measurement module may be connected or connectable to a control module configured for controlling the laser deflection unit of the laser processing device. The control module may be configured for generating control commands to the laser deflection unit. The control module may for example be a comprise a control card, such as an SP-ICE <NUM> control card of Raylase GmbH. The measurement module may be configured for reading a control command from the control module to the laser deflection unit, which may correspond to a target operation power of the laser deflection unit. The measurement module may be configured for detecting the target operation power as the parameter, the variation of which is detected by the measurement module. The measurement module may for example detect that the control module instructs the laser deflection unit to change the rotation speed of movable mirrors of the laser deflection unit from a first value to a second higher value and the regulation module may trigger, in reaction to such variation, a corresponding adaptation of the cooling power provided by the cooling system.

A second aspect of the invention refers to a laser system comprising a laser processing device, a cooling system, and a cooling control unit according to the first aspect of the invention, in particular according to any of the previously described embodiments.

The laser processing device may be configured for laser processing a workpiece and comprises a laser deflection unit for deflecting a laser beam. The deflection unit may be configured for controllably deflecting a laser beam to a target point in space, in particular to a target point on a work field of the laser processing device. Such deflection unit may comprise one or more movable mirrors. For example, the deflection unit may comprise a first movable mirror rotatable around a first axis and a second movable mirror rotatable around a second axis perpendicular to the first axis, i.e. a so-called pair of XY movable mirrors. The laser light generation device may be configured for generating a laser beam in a wavelength range from <NUM> to <NUM>, preferably from <NUM> to <NUM>. Within such wavelength ranges, the beneficial effects of the invention are particularly advantageous since, due to a small spot size, i.e. to a small laser beam spot or laser beam diameter on the work field and/or at the focal position of the laser beam, the laser processing is particularly sensitive to thermally induced variations.

The cooling system is configured for cooling the laser processing device, in particular the laser deflection unit and/or the laser light generation device. The cooling system may be configured for selectively controlling the flowing conditions and/or the temperature of a cooling fluid that is used for cooling the laser processing device, in particular the laser deflection unit and/or the laser light generation device. The flowing conditions may comprise a flowing velocity and/or a flux of the cooling fluid. The cooling control unit may be configured for controlling said flowing conditions and said temperature, by correspondingly controlling the cooling system. The cooling fluid may in particular be or comprise water or air.

In preferred embodiments, the cooling system may comprise a cooling fluid pump for controlling the flow conditions of a cooling fluid used for cooling the laser processing device, in particular the laser deflection unit and/or the laser light generation device thereof. Additionally or alternatively, the cooling system may comprise a temperature control circuit for controlling the temperature of the cooling fluid. The cooling control unit may be configured for controlling the fluid pump and/or the temperature control circuit to control the flow conditions and/or the temperature of the cooling fluid, respectively, based on the parameter of the electric power input.

A capacity of the cooling system to dissipate heat generated within the laser processing device, which may be determined by the flowing conditions of the cooling fluid, in particular by the flowing velocity and/or the temperature thereof, may be referred to as "cooling power". A higher cooling power, which may be achieved with higher flowing speed of the cooling fluid and/or with a lower temperature of the cooling fluid, may hence refer to a greater capacity to absorb heat, i.e. to cool down the laser processing device. A lower cooling power, which may be achieved with lower flowing speed of the cooling fluid and/or with a higher temperature of the cooling fluid, may hence refer to a lower capacity to absorb heat, i.e. to cool down the laser processing device.

As explained above for the embodiments of the first aspect of the invention, the cooling control unit is configured for controlling the cooling power of the cooling system based on a parameter of an electric power input received by the laser deflection unit of the laser processing device and detected by the cooling control unit. In particular, the cooling control unit may be configured for varying the cooling power of the cooling system when detecting a variation in the parameter of the electric power input, possibly by a at least given predefined difference, for example by <NUM>% or more, <NUM>% or more or <NUM>% or more. More specifically, the cooling control unit may be configured for increasing the cooling power of the cooling system when detecting an increase in the parameter of the electric power input and for reducing the cooling power of the cooling system when detecting a decrease in the parameter of the electric power input.

According to preferred embodiments, the laser system may further comprise a power supply device configured for providing an electric current to the laser processing device, in particular to the laser deflection unit of the leaser processing device. The power supply device may for example be configured for providing the electric current to the laser processing device with a predetermined electric current intensity and/or with a predetermined electric power. The control cooling unit may be connected with the power supply device. The measurement module of the cooling control unit may be configured for reading from the electric power supply device an electric parameter, like an electric current intensity or an electric power, of an electric current provided by the electric power supply device to the laser deflection unit of the leaser processing device. The regulation module of the cooling control unit may be configured for controlling the cooling power of the cooling system based on said electric parameter, which corresponds to said parameter.

In preferred embodiments, the laser processing device may comprise internal control circuitry configured for measuring an electric parameter of an electric current being input to the laser deflection unit of the leaser processing device. The measurement module of the control cooling unit may be connected with the internal control circuitry of the laser processing device and the regulation module of the cooling control unit may be configured for controlling the cooling power of the cooling system based on said electric parameter, i.e. using the electric parameter as the previously mentioned parameter, based on which the cooling power is controlled.

According to preferred embodiments, the laser system may further comprise an electric sensor, for example a multimeter, configured for measuring an electric parameter of an electric current being input, for example by a power supply device, to the laser deflection unit of the leaser processing device. The electric parameter may for example by an electric current intensity or an electric power. The measurement module of the control cooling unit may be connected with the electric sensor and may be configured for reading the electric parameter measured by the electric sensor. The regulation module of the cooling control unit may be configured for controlling the cooling power of the cooling system based on the electric parameter measured by the electric sensor, i.e. using the electric parameter as the previously mentioned parameter, based on which the cooling power is controlled.

A third aspect of the invention refers to a method of controlling a laser system according to any of the previously described embodiments of the second aspect of the invention, in particular using a cooling control unit according to any of the embodiments of the first aspect of the invention. The method may be a computer-implemented method and may be implemented by the cooling control unit. The method comprises: detecting a parameter of an electric power input received by a laser deflection unit of a laser processing device of the laser system and determining whether the parameter is varying; and if the parameter is varying, controlling the cooling system of the laser system to vary a cooling power of the cooling system based on a variation of the parameter. In particular, the method may comprise detecting whether the parameter is increasing or decreasing and controlling the cooling system based thereon, to increase or decrease the cooling power of the cooling system if the parameter is varying, possibly by a at least given predefined difference, for example by <NUM>% or more, <NUM>% or more or <NUM>% or more. Thereby, the method may preventively prevent and compensate thermal variations within the laser processing device.

Detecting the parameter received by the laser processing device may comprise detecting a value of the parameter and controlling the cooling system based on the parameter may comprise setting the cooling power of the cooling system to a target cooling power value based on the value of the parameter according to a first predefined model, which may correspond to the first predefined model referred to above.

Detecting the parameter received by the laser processing device may, additionally or alternatively, comprise detecting a variation rate of the parameter and controlling the cooling system based on the parameter may comprise setting a variation rate of the cooling power to a target cooling power variation rate based on the variation rate of the parameter according to a second predefined model, which may correspond to the second predefined model referred to above.

The electric power input corresponds to an electric current or a control command provided or to be provided to the laser deflection unit of the laser processing device. The electric current may preferably comprise one or more of an electric current generated by a power supply device connected to the laser processing device, an electric current measured by the laser processing device, in particular by internal control circuitry, corresponding to electric current being input to the laser processing device, and an electric current measured by an electric sensor connected between a power supply device and the laser processing device. The parameter may be an electric current intensity and/or an electric power.

The previously mentioned control command may be provided to the laser deflection unit for example by a control module like the previously described control module. The parameter may preferably correspond to a target operation of the laser deflection unit of the laser processing device.

"Target operation" may refer herein to any action implementable by the the laser processing device, in particular the laser deflection unit ice thereof, in the course of a laser process, which may be associated with a variation in an electric current required by the laser deflection unit. For example, a target operation "begin rotating mirror", or "increase rotation speed of mirror" aimed at the laser deflection unit may be associated with an increase in the electric current intensity required by the laser deflection unit. In the method of the invention, the cooling power of the control system may be adapted in reaction to such example operation.

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to specific preferred embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated apparatus and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur now or in the future to someone skilled in the art to which the invention relates within the scope defined by the claims.

<FIG> shows a schematic view of a laser processing device <NUM>, for example an additive manufacturing device, including a laser light generation device <NUM>, provided in the form of a laser source device, and a laser deflection unit <NUM> comprising a pair of XY movable mirrors 32a and 32b. A laser beam L generated by the laser light generation device <NUM> is controllably deflected by the movable mirrors 32a, 32b of the laser deflection unit <NUM> towards a work field <NUM> for laser processing a workpiece W through a laser transparent window <NUM> formed in a housing <NUM>. The housing <NUM>, which can be dust-tight and air-tight, encloses the laser deflection unit <NUM> and the laser light generation device <NUM> at least in part. The laser processing device <NUM> can include other optical and/or electronic components (not-shown in <FIG>), such as a focusing device for focusing the laser beam L on the work field <NUM>, which can be arranged along the path of the laser beam L between the laser light source <NUM> and the laser deflection unit <NUM>.

The laser processing device <NUM> is connected with a cooling system <NUM> that is configured for cooling the laser processing device <NUM>, in particular the laser deflection unit <NUM> and the laser light generation device <NUM>. A cooling effect provided by the cooling system <NUM> can be transmitted over a cooling circuit with a cooling fluid such as water or air, which is circulated through the laser processing device in order to absorb and extract from the laser processing device <NUM> heat, for example heat produced by the laser deflection unit <NUM> and/or the laser light generation device <NUM>. The cooling effect provided by the cooling system helps maintaining thermal stability in the laser processing device <NUM>. If thermal stability is lost due to the heat generated by the laser deflection unit <NUM> and/or the laser light generation device <NUM>, it may cause malfunctioning of the laser processing device <NUM> and a corresponding loss of laser precision for laser-processing the workpiece W. This can be prevented or attenuated by the cooling system <NUM>.

The laser processing device <NUM> is also connected to a cooling control unit <NUM> that is configured for controlling the action of the cooling system <NUM> upon the laser light generation device <NUM> and the laser deflection unit <NUM> so as to preventively provide thermal stability within the laser processing device <NUM>.

<FIG> schematically illustrate the functional blocks of different embodiments of a laser system <NUM> including the laser processing device <NUM> and the cooling control unit <NUM> shown in <FIG>. In <FIG>, the internal details of the laser processing device <NUM> are not shown in detail. Instead, only the laser deflection unit <NUM> and the laser light generation device <NUM> are schematically shown as internal components of the laser processing device <NUM>.

In each of <FIG>, the laser processing device <NUM> is provided by an electric power supply device <NUM> with an electric power input in the form of an input electric current. The electric power supply device <NUM> can for example comprise a source of electric current with desired values of electric current intensity, power and/or voltage. In each of the embodiments shown in <FIG>, the electric current provided by the electric power supply device <NUM> is understood to be provided to the laser deflection unit <NUM>.

By way of example, the electric current may be provided to the laser deflection unit <NUM> as a control signal with a given electric current intensity for controlling a movement of the movable mirrors 32a, 32b thereof.

Also shown in each of <FIG>, is the cooling system <NUM>, which is configured for establishing a controlled circulation of a cooling fluid to and from the laser processing device <NUM>. The circulation of the cooling fluid provided by the cooling system <NUM> is understood herein to be provided to the laser processing device <NUM> including to each of the laser deflection unit <NUM> and the laser light generation device <NUM>. However, in other related embodiments, the circulation of the cooling fluid may be provided to one of the laser light generation device <NUM> and the laser deflection unit <NUM>. The cooling system <NUM> comprises a pump <NUM> configured to control the flowing conditions of the cooling fluid, including a flow velocity, and a heat exchanger <NUM> configured for controlling a temperature of the cooling fluid. The flow of the cooling fluid between the cooling system <NUM> and the laser processing device <NUM> is represented in <FIG> by arrows <NUM> extending from the cooling system <NUM> to the laser processing device <NUM> and vice versa.

The cooling control unit <NUM>, which may be a software running on a computer or on a dedicated processing unit, is connected to the cooling system <NUM> and to the laser processing device <NUM>. The cooling control unit <NUM> comprises a measurement module <NUM> and a regulation module <NUM>.

In some embodiments, as shown in <FIG>, the cooling control unit <NUM>, which can be integrated in a larger control unit, is configured for controlling the laser deflection unit <NUM> and/or the laser light generation device <NUM> over a control connection <NUM>.

In the embodiment shown in <FIG>, the laser processing device <NUM> is a digital laser processing device that comprises an internal control circuitry <NUM> that is configured for measuring an electric current intensity of an electric current provided by the electric power supply device <NUM> to the laser deflection unit <NUM> and to provide the measured value of the electric current intensity to the cooling control unit <NUM>, in particular to the measurement module <NUM>. Although schematically represented herein, in general, as an internal component of the laser processing device <NUM>, the internal control circuitry <NUM> can be, in some embodiments, an internal component of the laser deflection unit <NUM>. By reading the electric current intensity measured by the internal control circuitry <NUM>, the measurement module <NUM> can monitor in real-time the electric current intensity of the electric current provided by the electric power supply device <NUM> that enters the laser processing device <NUM> as an electric energy input to the laser deflection unit <NUM>.

If the measurement module <NUM> determines that the value of the electric current intensity measured by the internal control circuitry <NUM> is varying, for example by <NUM>% or more, the regulation module <NUM> sends to the pump <NUM> and/or the heat exchanger <NUM> a cooling control signal transmitted through a connection <NUM>, which causes the cooling system <NUM> to correspondingly vary a cooling power provided to the laser processing device <NUM>, in order to preventively adapt the cooling conditions provided to the laser processing device <NUM> so as to maintain thermal stability therein.

For example, if the measurement module <NUM> detects that the internal control circuitry <NUM> is measuring an increasing electric current intensity, the regulation module <NUM> can generate a cooling control signal that controls the cooling system <NUM> to increase the cooling power provided to the laser processing device <NUM>. If the measurement module <NUM> detects that the internal control circuitry <NUM> is measuring a decreasing value of electric current intensity, the regulation module <NUM> can generate the cooling control signal to control the cooling system <NUM> decrees the cooling power provided to the laser processing device <NUM>.

The cooling power provided by the cooling system <NUM> can be increased by decreasing the temperature to which the heat exchanger <NUM> cools down the cooling fluid coming from the laser processing device <NUM> before returning it to the laser processing device <NUM> and/or by increasing the velocity of flow of the cooling fluid by correspondingly increasing the pumping power of the pump <NUM>. Likewise, the cooling power provided by the cooling system <NUM> can be decreased by increasing the temperature to which the heat exchanger <NUM> cools down the cooling fluid and/or by decreasing the pump power provided by the pump <NUM> to the cooling fluid.

By controlling the cooling power provided by the cooling system <NUM> to the laser processing device <NUM> based on a measurement of an electric power input provided to the laser processing device <NUM>, the cooling control unit <NUM> implements a predictive cooling scheme that allows countering uncontrolled variations of thermal conditions of the laser processing device <NUM> before they are caused by variations in the electric power input provided to the laser processing device, in this case by variations in the electric current intensity of the electric current provided by the electric power supply device <NUM>. Thus, variations in the electric power input provided of the laser processing device <NUM> are used by the cooling control unit <NUM> as an indicator of upcoming thermal fluctuations in the laser processing device <NUM> to be compensated by the cooling system <NUM>.

The regulation module <NUM> can operate based on a first predefined model that maps values of the electric current intensity I delivered by the electric power supply device <NUM> to respective target cooling power values, which may for example correspond to pairs of values of the pump power P provided by the pump <NUM> and the temperature T to which the heat exchanger <NUM> cools down the cooling fluid. For example, the first predefined model may be represented by functions: <MAT> wherein a and c are empirically predetermined proportionality factors and b and d are empirically predetermined calibration constants. Thus, the functions P and T define a target cooling power as a function of I.

Additionally or alternatively, the measurement module <NUM> can be configured for generating the control signal to control the cooling power provided by the cooling system <NUM> to the laser processing device <NUM> based on a second predefined model represented by the functions: <MAT> wherein P', I' and T' respectively represent time derivatives (i.e. variation rates) of P, I and T, wherein a' and c' are empirically predetermined proportionality factors and b' and d' are empirically predetermined calibration constants. The functions P' and T' define a target cooling power variation rate as a function of a variation rate of I.

The embodiment illustrated in <FIG> differs from the embodiment illustrated in <FIG> in that the electric current intensity of the electric current provided by the electric power supply device <NUM> to the laser processing device <NUM> is measured by an external electric sensor <NUM> rather than by the internal control circuitry <NUM> of the embodiment shown in <FIG>. The electric sensor <NUM> can comprise a multimeter and provides a measurement of the electric current intensity that is read and monitored by the measurement module <NUM> of the cooling control unit <NUM>, which otherwise operates explained above for the exemplary embodiment of <FIG>.

The embodiment illustrated in <FIG> differs from the exemplary embodiments illustrated in each of <FIG> and <FIG> in that, rather than obtaining a measurement of the electric current intensity of the electric current provided by the electric power supply device <NUM> (cf. internal control circuitry <NUM> in <FIG> and electric sensor <NUM> in <FIG>), the cooling control unit <NUM>, in particular the measurement module <NUM>, is in direct communication with the electric power supply device <NUM> to read the value of the electric current intensity being provided by the electric power supply device <NUM>, for example by accessing control settings and/or internal circuitry of the electric power supply device <NUM>. Other than that, the cooling control unit <NUM> of the exemplary embodiment shown in <FIG> operates as described above for the exemplary embodiment shown in <FIG>.

In the exemplary embodiment schematically illustrated in <FIG>, the difference with respect to the exemplary embodiment illustrated in <FIG> is that, rather than being in direct communication with the electric power supply device <NUM>, the cooling control unit <NUM>, in particular the measurement module <NUM>, is in communication with a control module <NUM>. The control module <NUM>, which can be hardware-implemented or software-implemented, possibly under the same platform or processor as the cooling control unit <NUM>, is in communication with the laser processing device <NUM>, over a first control connection <NUM>, and with the electric power supply device <NUM>, over a second control connection <NUM>.

The control module <NUM> controls the operation of the laser deflection unit <NUM> and the laser light generation device <NUM> as well as the properties of the electric current provided by the electric power supply device <NUM> to the laser processing device <NUM>. The control module <NUM> sends control commands to the laser deflection unit <NUM> and the laser light generation device <NUM> to laser process the workpiece W shown in <FIG>. Further, the control module <NUM> controls the electric power supply device <NUM> to provide to the laser processing device <NUM> the electric current required for laser-processing the workpiece W, for example according to a predefined or programmed laser processing scheme.

The measurement module <NUM> of the cooling control unit <NUM> is configured to read the control commands issued by the control module <NUM> that are related to a corresponding target operation power of the laser deflection unit <NUM>. When a variation in any of these target operation powers is detected by the measurement module <NUM>, the regulation module <NUM> implements the predictive cooling scheme explained above for <FIG>.

Additionally or alternatively, the adjustment of the cooling power provided by the cooling system <NUM> can be triggered based on a control command issued by the control module <NUM> to the electric power supply device <NUM>. For example, when the control module <NUM> instructs the electric power supply device <NUM> to increase the electric current intensity of an electric current provided to the laser processing device <NUM>, either directly or in relation with a corresponding setting of a target operation power of the laser deflection unit <NUM> (e.g. increase rotation speed of mirror 32a and/or 32b), this command can be detected by the measurement module <NUM>, which triggers the regulation module <NUM> to correspondingly increase the cooling power provided by the cooling system <NUM> the laser processing device <NUM>, such that thermal stability is preserved at the laser deflection unit <NUM> and/or at the laser light generation device <NUM>.

<FIG> shows a schematic flow diagram of a method <NUM> of controlling the laser system <NUM> shown in <FIG>, <FIG>, which is implemented by the cooling control unit <NUM>. At <NUM>, a value of the electric current intensity I of an electric current provided to the laser deflection unit <NUM>, is detected, in particular by the measurement module <NUM>.

At <NUM>, the condition is checked whether the electric current intensity I is varying. This may comprise detecting whether I is varying by a predefined variation, for example by <NUM>% or more. If this is the case, the method <NUM> proceeds to <NUM>.

At <NUM>, the cooling system <NUM> is controlled to adapt the cooling power provided to the laser processing device <NUM>, for example by correspondingly adapting a pumping power of the pump <NUM> and/or a temperature of operation of the heat exchanger <NUM>, in order to compensate for thermal variations that are expected in the laser processing device <NUM> in view of the variation of I. Step <NUM> can be implemented by the regulation module <NUM> of the cooling control unit <NUM>.

In other related embodiments of a method like method <NUM>, a parameter different from the electric current intensity I may be used for monitoring the electric current provided to the laser processing device, for example an electric voltage (measurable in volts or in subunits thereof) or an electric power (measurable in watts or in subunits thereof).

<FIG> shows a flow diagram of a method <NUM>' implemented by the cooling control unit <NUM> of the exemplary embodiment of <FIG>. At <NUM>', a velocity v at which one or both of the mirrors 32a, 32b of the laser deflection unit <NUM> should operate according to a control command issued by the control module <NUM> is detected by the detection module <NUM> of the cooling control unit <NUM>.

At <NUM>', the measurement module <NUM> determines whether v is varying. If v is varying, possibly by a predefined difference, for example by at least <NUM>%, the method <NUM>' continues to <NUM>'.

At <NUM>', the regulation module <NUM> of the cooling control unit <NUM> controls the cooling system <NUM> such that the cooling power provided to the laser processing device <NUM>, in particular to the laser deflection unit <NUM>, varies according to the variation detected for v.

Claim 1:
A cooling control unit (<NUM>) for controlling a cooling system (<NUM>) of a laser processing device (<NUM>), wherein the cooling control unit (<NUM>) comprises:
a measurement module (<NUM>) configured for detecting a parameter of an electric power input provided to a laser deflection unit (<NUM>) of the laser processing device (<NUM>) and for determining whether the parameter is varying, wherein the electric power input corresponds to an electric current or a control command provided to the laser deflection unit (<NUM>); and
a regulation module (<NUM>) configured for generating a cooling control signal for controlling the cooling system (<NUM>) based on the parameter to vary a cooling power of the cooling system (<NUM>) if the measurement module (<NUM>) determines that the parameter is varying.