Method of cutting a metal workpiece

Abstract

The present application relates to a flat-bed laser cutting machine (1). The flat-bed laser cutting machine (1) has a workpiece support defining a horizontal support area for a workpiece (5). The flat-bed laser cutting machine further comprises a laser cutting head (210) disposed above the support area and equipped to emit a laser cutting beam (3) towards a workpiece (5) supported by the workpiece support and to move in a horizontal direction relative to the workpiece (5) and the workpiece support. Furthermore, the flat-bed laser cutting machine comprises an energy collection device (50) having a collection structure below the support area and equipped to collect radiant energy of laser radiation running from the laser cutting head (211) that is not affected by the workpiece (5) and / or radiant energy of laser radiation from the laser cutting head (211) and reflected by a cutting front surface area. The energy collection device (50) is equipped to recycle the radiant energy collected by the structure.

Description

Technical Field

[0001] This invention belongs to the field of flatbed laser cutting machines. Background Technology

[0002] A flatbed laser cutting machine includes a workpiece support that defines a generally horizontal support area and supports a workpiece thereon, which may be, for example, a sheet or plate of material to be cut. The machine also includes a laser cutting head configured to emit a laser cutting beam having a direction perpendicular to the support area. The laser cutting head is configured to move relative to the workpiece support in at least two horizontal dimensions to perform the desired cut.

[0003] Recently, the demand for laser power exceeding, for example, well beyond 1 kW appears to be increasing dramatically. However, it can be observed that only a small portion of the laser beam power is actually coupled into the workpiece, causing localized melting or burning of the workpiece material; that is, only a small portion of the energy is actually available for cutting. Therefore, the energy efficiency of flatbed laser cutting machines is very low, and there is a desire to increase energy efficiency.

[0004] JP 2016 / 034649A discloses a laser beam cutting machine with a brush support or a roller support. This laser beam cutting machine has a laser cutting head capable of moving along a horizontal direction (Y), such that the laser cutting beam extends in a plane (YZ plane), and a workpiece support has a slit 21 extending in this plane, with a waste box 9 below the slit 21. The workpiece W is capable of moving on the workpiece support in another horizontal direction (X). JP 2016 / 034649A does not propose any measures to address the challenges posed by the need for higher laser power in laser cutting machines. Furthermore, JPH 02142696A discloses a flatbed laser cutting machine, which also does not propose any measures to address these challenges.

[0005] US 2015 / 0224601 relates to a method for recovering unused optical radiation energy from machinery. This method is based on the concept of converting radiation energy not absorbed by the workpiece and trapped in a beam trap into electrical energy, for example, through a photovoltaic device or also through a heat engine and generator. The beam trap is a generally hollow structure that allows radiation from a beam to enter through a small light-entry opening, but prevents the radiation from escaping through the interaction between its geometry and a suitable coating. Summary of the Invention

[0006] The purpose of this invention is to provide a flatbed laser cutting method that overcomes the shortcomings of existing methods. In particular, the purpose of this invention is to provide a flatbed laser cutting method with improved overall energy efficiency at high laser power.

[0007] This objective is achieved by providing a flatbed laser cutting machine having a workpiece support defining a horizontal support area for a workpiece, such as a sheet or plate of metal, placed thereon. The flatbed laser cutting machine also includes a laser cutting head configured to emit a laser cutting beam toward the workpiece supported by the workpiece support, for example, in a direction substantially perpendicular to the support area, and additionally emit a processing gas (sometimes referred to as "auxiliary gas") toward the workpiece, particularly toward the incident position of the laser cutting beam on the workpiece. The laser cutting head is positioned above the support area and configured to move horizontally; typically, the laser cutting head has two degrees of freedom (i.e., in one set of embodiments, if the z-direction is defined as the direction of the laser beam, the laser cutting head can move in both the x and y directions). The flatbed laser cutting machine also includes an energy harvesting device having a collection structure disposed below the support area and arranged and configured to collect the radiant energy of laser radiation traveling from the laser cutting head that is not affected by the workpiece and / or the radiant energy of laser radiation from the laser cutting head and reflected by the surface area of ​​the cutting front edge, wherein the energy harvesting device is configured to recover the radiant energy collected by the collection structure.

[0008] Radiation irradiating a workpiece is either absorbed or reflected by the workpiece. Only absorbed radiation can locally heat the workpiece and facilitate the cutting process. Many materials to be cut are metals, which typically have high reflectivity, resulting in a high proportion of reflected radiation. This invention is based on the understanding that, for reasons explained in more detail below, most of the reflected radiation is reflected downwards—the thicker the workpiece, the higher the proportion of radiation reflected downwards. Similarly, the thicker the workpiece, the closer the direction of radiation reflection is to the vertical direction. Furthermore, the thicker the workpiece, the smaller the proportion of radiation absorbed. Moreover, in reality, the speed at which the laser beam moves relative to the workpiece does not correspond to an ideal value, but is less than the ideal value, causing a portion of the laser radiation to not interact with the workpiece at all, but to propagate directly downwards.

[0009] In this implementation, the laser cutting beam can be emitted vertically.

[0010] As mentioned above, in this embodiment, the laser cutting head is configured to simultaneously emit a laser cutting beam downwards, for example vertically, toward the workpiece and to blow processing gas toward the workpiece and toward the incident position along at least two horizontal directions. "Emitting downwards" does not preclude the laser cutting beam from traveling at an angle other than 90° to the horizontal plane, for example, when the laser cutting head is configured to be tilted relative to the vertical direction. However, in this embodiment, the laser cutting head is designed for vertical emission of the laser cutting beam.

[0011] As is known in laser processing, the fact that a laser cutting head is equipped to emit a laser cutting beam as it moves in the horizontal direction does not preclude the possibility that it may also move without emitting a beam, for example, to the position where the cutting begins (the piercing position).

[0012] In embodiments where the laser cutting head can move in two horizontal directions, the workpiece can be placed statically on the workpiece support and does not need to be moved. This is advantageous in terms of handling, especially when the workpiece can initially be large, and also advantageous in terms of achievable processing speeds. The present invention recognizes that, also in these cases, it is meaningful and possible to collect and recover the energy emitted downwards towards the workpiece.

[0013] Because if the laser cutting head moves along two horizontal directions, the laser radiation energy emitted downwards towards the workpiece can be incident on a relatively large area. According to the first method, the collection structure extends accordingly to cover the large area below the workpiece. In an example, the collection structure may include an open container below the workpiece. This open container will then also receive cutting waste blown downwards by the emission of processing gas. As explained in more detail herein, the machine can be configured to remove this cutting waste. In other examples, a moving structure, such as a cooling conveyor, may be included. According to the second method, the collection structure can be movable and can be configured to follow the movement of the laser cutting head, particularly along one of the horizontal directions, while the collection structure can extend along the other horizontal direction.

[0014] A process gas emitted toward the workpiece is used to assist the laser cutting process. Process gas-assisted laser cutting is performed by blowing molten workpiece material downwards from the cutting front and cooling the workpiece immediately adjacent to the incident position of the laser beam. If the process gas contains oxygen, it can also assist by inducing additional heat generation at the incident position (reactive laser cutting).

[0015] The flatbed laser cutting machine described herein can be configured to emit a laser with a power of at least 1 kW, particularly at least 5 kW or at least 10 kW.

[0016] High-power laser cutting machines are particularly useful for cutting thick workpieces. Therefore, the above understanding reveals that for high-power laser cutting machines, not only will there be more power, but also a higher proportion of unused power radiating downwards to the support area.

[0017] This makes the collection structure beneath the support area particularly valuable.

[0018] In order to recover the collected radiant energy, the energy harvesting device includes corresponding energy recovery equipment.

[0019] In this context, recycling can include directly or indirectly converting radiant energy into electrical energy.

[0020] As an example of direct conversion, the collection structure may include a photoelectric unit and / or a reflector, as well as an energy recovery device. This energy recovery device is an arrangement of the photoelectric unit such that radiation reflected by the reflector irradiates the photoelectric unit. In this case, the reflector may be configured, for example, to induce diffuse reflection, so as to distribute the remaining laser radiation energy over a relatively large area, thereby keeping the energy density on the surface of the photoelectric unit within a reasonable range.

[0021] Indirect conversion into electrical energy can include irradiating a collecting structure with radiant energy (or, if the collecting structure includes a reflector, irradiating the structure with reflected radiant energy) to heat the collecting structure. The heat can then be converted into electrical energy by a heat engine and a generator, or by a thermoelectric converter (thermoelectric generator) device, such as a Peltier element using the Seebeck effect (also known as a Seebeck generator).

[0022] Whether through direct or indirect conversion, not all heat generated by radiation can be converted into electrical energy. The remaining heat can optionally be used directly for heating, warm water production, etc.; this includes the possibility of storing the heat in a heat storage tank for later use. Alternatively, the remaining heat can be dissipated, for example, by cooling water or by a structure with cooling fins.

[0023] As an alternative to converting heat into electricity, heat can be used directly, such as for heating or producing warm water. This includes the possibility of storing heat in a heat storage tank for later use.

[0024] All combinations of options are possible. In the example, radiation first strikes the photoelectric unit via a reflector. Secondly, the heat generated by the photoelectric unit and / or the heat generated in the secondary collection structure and / or in the reflector by the radiation reflected from the photoelectric unit can be collected by a regenerating fluid and supplied to the indirect conversion device. The remaining heat that is not converted—but accumulates, for example, in the coolant circuit cooling the indirect conversion device—can be used directly for heating, etc. As another example, the photoelectric unit can be arranged peripherally relative to the collection structure, wherein the collection structure is configured to absorb the main portion of the radiation, and the photoelectric unit is arranged to collect the portion of radiation not absorbed by the collection structure.

[0025] Whether the conversion is direct or indirect, and if the heat is used directly, the energy harvesting device can be configured to contact the regenerating fluid—especially a liquid, and therefore a cooling liquid—with the harvesting structure. The regenerating fluid can carry away the heat, as the machine can be configured to transfer heat from the harvesting structure. For example, the regenerating fluid can be transferred to energy recovery equipment, such as equipment used for the aforementioned indirect conversion to electricity. In addition to transferring the cooling liquid to energy recovery equipment, or as an alternative, the machine can transfer the regenerating fluid to a heat storage tank and / or heat exchanger for direct use of the heat.

[0026] In both cases with and without energy recovery equipment, a primary and secondary regenerative fluid loop can be used, with a heat exchanger between them. Embodiments with a primary and secondary regenerative fluid loop—where the primary regenerative fluid is in contact with the collection structure and the secondary regenerative fluid is in contact with the energy recovery equipment, heat storage unit, or heat exchanger—are particularly advantageous, but not only in embodiments where the (primary) regenerative fluid may be contaminated.

[0027] The energy recovery scheme used may also include cooling of the laser source itself, and / or, in the case of optical pumping of the laser, cooling of the pump source. For example, the regenerating fluid can cool the laser source and / or pump source before contacting the collection structure, thereby preheating the regenerating fluid. This is especially true when using a conversion device that functions as a heat engine.

[0028] The collecting structure will have a physical shape and location that makes it suitable for collecting the radiant energy of laser radiation.

[0029] According to the first set of embodiments, the cooling device and collecting structure extend below the support region to cover a relatively large portion of the support region, such as essentially the entire support region. Specifically, this means that the projection of the support structure onto the support region along the -z direction (i.e., the direction opposite to the direction of laser beam propagation) covers a large portion of the support region, such as at least 60%, at least 70%, at least 80%, or even at least 90%. In this case, the support region is defined as an area in a plane in which a workpiece can be placed, extending horizontally and reaching all locations where the laser beam can travel to cut the workpiece—therefore, this area is the region that can be processed by the laser cutting beam.

[0030] The concept that the collecting structure extends below the support area to cover a relatively large portion of the support area means that regardless of where the laser head moves relative to the workpiece, the probability of radiation radiating through the support area into the -z direction hitting the collecting structure is high. Due to the aforementioned understanding that the unabsorbed radiation radiates primarily directly downwards, essentially in the -z direction, this ensures that the majority of the unabsorbed radiation can be collected to protect the machine base.

[0031] Examples of embodiments in the first group include, for instance, a container with a regenerating fluid. Such a container can, for example, be inserted into and retracted from the machine base. In one embodiment, the container can be constructed as a trolley. This container below the support area—and if the regenerating fluid itself also absorbs radiation—belongs to a collection structure. Such a configuration can be implemented directly. However, if the container is open on top, cutting waste will accumulate in the container, and therefore, embodiments with such open containers require good filtration and frequent replacement of the regenerating fluid.

[0032] Another embodiment of the second group includes a collection structure comprising a conveyor configured to continuously or intermittently transport cutting waste from below the support area.

[0033] In the first subgroup of implementations, the concepts of a container and a conveyor are combined, wherein the conveyor is at least partially immersed in a regenerating fluid. Cutting waste, which in most cases has a higher density than commonly used liquids (such as water), will sink in the container and be collected by the conveyor, thereby allowing the cutting waste to be conveyed out of the container. In addition to transferring heat, the regenerating fluid also has the effect of preventing any non-solid fragments of cutting waste from directly contacting the conveyor. In other words, the cutting waste will be sufficiently cooled by the regenerating fluid to ensure that it exists as a solid when in contact with the conveyor, thereby ensuring that the cutting waste does not adhere to the conveyor.

[0034] In the second subgroup of the first set of embodiments, the conveyor is not immersed in the regenerating fluid at the location where unabsorbed radiation strikes the conveyor. Instead, residual laser radiation, i.e., laser radiation not absorbed by the workpiece, directly (and / or indirectly via reflection) irradiates the conveyor belt, heating it. The heat can then be removed from the conveyor using the regenerating fluid. For example, the conveyor may include a thermal contact structure that contacts the regenerating fluid. In one embodiment, this thermal contact structure contacts a bath of the regenerating fluid, in which case no pipes or the like are required to participate in the movement of the conveyor. In an example, the contact structure may include a protrusion of the conveyor, etc., and a bath of the regenerating fluid, in which the protrusion or the like is immersed.

[0035] In the second set of embodiments, the collection structure does not need to extend like the processing area, but the collection structure is a movable collection structure and is configured to cooperate in at least some movements of the laser head relative to the support area.

[0036] Specifically, the flatbed laser cutting machine may include a bridge-like component on which the laser cutting head is mounted, and the laser cutting head is movable relative to the bridge-like component along a first horizontal dimension (x-axis). The bridge-like component as a whole is movable relative to the workpiece support along a second horizontal dimension (y-axis). This is a common structure for flatbed laser cutting machines. According to an embodiment in the second set of embodiments, a collection structure, as a movable collection structure, is connected to the bridge-like component and moves together with the bridge-like component along the y-axis, i.e., in the positive and negative y directions.

[0037] In particular, in such an implementation, the (movable) collection structure may include a liquid delivery pipe for conveying the regenerative fluid. The pipe may be positioned substantially parallel to the x-axis and move together with the bridge-like member in the y-dimensional direction.

[0038] In one embodiment, the liquid delivery pipe serving as the collection structure has a cross-section that is not circular, although in other embodiments the cross-section is circular. Specifically, the cross-section can be optimized to prevent cutting waste from adhering to the collection structure. The cross-section can extend, for example, to the edge of the side portion, thus extending to an angle in the cross-section perpendicular to the longitudinal extension of the liquid delivery pipe. Alternatively or as an alternative, the horizontal dimension of the cross-section (the y-dimensional in the example above, where the cross-section is again perpendicular to the longitudinal extension, e.g., corresponding to the cross-section in the yz plane) can be smaller than the vertical extension.

[0039] The collection structures in the embodiments mentioned above are configured to absorb residual laser radiation (or at least a majority thereof) for direct or indirect conversion into electricity and / or usable heat. The surface portions of the collection structure may be accordingly equipped, for example, with a chemical composition that favors the absorption of the laser beam's wavelength, and / or with a corresponding structure, such as a corresponding roughness. In embodiments where the radiation also directly irradiates the regenerating fluid, the regenerating fluid may, for example, be dyed to absorb the radiation.

[0040] In addition to absorbing unused radiation, or as an alternative, the collection structure may include a reflective surface portion that guides the radiated portion to the absorbing element of the energy harvesting device, such as a photosensitive panel. This absorbing element may—but is not necessarily required—be positioned below the support area.

[0041] This invention relates to a method for laser cutting metal workpieces, particularly flat metal workpieces (and thus, metal sheets or plates), using a flatbed laser cutting machine laser as disclosed herein. The laser cutting involves moving the laser cutting head relative to the workpiece while simultaneously emitting a laser cutting beam toward the workpiece and blowing a processing gas toward the workpiece (of course, as is generally known in laser cutting, this does not preclude the possibility that the laser cutting head may also move during laser beam shutdown). Specifically, in embodiments, the laser cutting beam may be emitted vertically and perpendicular to the (upper) surface of the workpiece, and a collection structure is vertically positioned below the incident position of the laser beam on the workpiece, while the processing gas is sprayed onto the incident position of the laser beam on the workpiece.

[0042] This method can be specifically performed by a flatbed laser cutting machine for cutting metal workpieces. The laser cutting machine has a workpiece support defined by a support grid, the workpiece support defining a horizontal support area for the metal workpiece. The flatbed laser cutting machine also includes a laser cutting head disposed above the support area and configured to emit a laser cutting beam toward the workpiece supported by the workpiece support, in addition to emitting a processing gas toward the workpiece, and configured to move horizontally relative to the workpiece and the workpiece support. The machine is characterized by an energy harvesting device, which includes a harvesting structure located below the support grid and configured to collect the radiant energy of laser radiation traveling from the laser cutting head unaffected by the workpiece and / or the radiant energy of laser radiation from the laser cutting head and reflected by the surface area of ​​the cutting front edge. The energy harvesting device is configured to recover the radiant energy collected by the harvesting structure. Attached Figure Description

[0043] In the following description, embodiments of the invention are described in more detail with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same or similar parts. The drawings show:

[0044] Figure 1 Flatbed laser cutting machine;

[0045] Figure 2 : The cross-section of the workpiece at the cutting edge;

[0046] Figure 3 The approximate absorption coefficient of steel for unpolarized light varies with the incident angle;

[0047] Figure 4 : In non-ideal circumstances and Figure 2 The cross section corresponding to the cross section;

[0048] Figure 5 Flatbed laser cutting machine with a cooled machine base;

[0049] Figure 6The trolley for this laser cutting machine;

[0050] Figure 7 The principle of a belt conveyor immersed in a regenerating fluid bath;

[0051] Figure 8 Another embodiment of a belt conveyor with a regenerating fluid bath;

[0052] Figure 9 : Figure 8 Variations of the implementation method;

[0053] Figure 10 : Figure 8 Another variation of the implementation method;

[0054] Figure 11 : Figure 8 Another variation of the implementation method;

[0055] Figure 12 Another implementation method for a flatbed laser cutting machine;

[0056] Figures 13 to 16 Used for Figure 12 The cross-section of the liquid delivery pipe in the embodiment of the invention; and

[0057] Figure 17 Another implementation method for flatbed laser cutting machines. Detailed Implementation

[0058] Figure 1 An example of a laser cutting machine 1 is shown. The machine includes a laser source 201, a transmission optical fiber 212, a laser cutting head 210, and a laser cutting head moving mechanism. The workpiece 5 is supported by a workpiece support (…). Figure 1 (Not shown in the image) Support. The laser cutting head moving mechanism includes a bridge-like member 202, with the laser cutting head 210 movable relative to the bridge-like member 202 in the x-direction. The bridge-like member 202 itself is movable relative to the processing table and the workpiece 5 in the y-direction, for example, on a pair of guide rails. During operation, as the laser cutting head 210 moves relative to the workpiece 5, it emits a laser cutting beam 3 downward in a generally vertical direction onto the workpiece 5 to form a kerf (cut 51). Additionally, the laser cutting head 210 jets a process gas towards the incident position of the laser cutting beam 3 on the workpiece 5. The workpiece 5 may be a metal plate cut by the laser cutting beam emitted from the laser cutting head.

[0059] During laser cutting operations, high-speed and high-acceleration movements are required in both the x and y directions within the processing area. Movement in the y direction involves moving the entire bridge-shaped member 202 together with the cutting head.

[0060] Even if the laser beam is irradiated from a direction perpendicular to the support area (which is defined by the processing table and corresponds to the lower surface of the plate-shaped workpiece 5 in the described embodiment), the incident angle is much greater than 0°. Figure 2 The diagram illustrates the cutting front 53 as the laser cutting beam 3 moves relative to the workpiece 5 along the cutting direction 54. (As can be seen from...) Figure 2 The minimum angle of incidence seen in the image is

[0061] α 最小 =tan -1 (t / w),

[0062] Here, t is the thickness of the workpiece, and w is the width (average diameter) of the laser beam passing through the workpiece. For relatively thick workpieces—which are typically cut by high-power laser beams—the minimum angle of incidence becomes relatively large. For example, for a workpiece with a width w = 200 μm and a thickness t between 2 mm and 20 mm, the minimum angle of incidence is between 84° and 89.5°. Due to geometry, the maximum angle of incidence is 90°.

[0063] The absorption coefficient is a property of a material and describes how much light energy the material can absorb. In addition to material properties, the degree of absorption also depends on the angle of incidence, wavelength, and polarization. Figure 3 The approximate absorption coefficient A of unpolarized (or circularly polarized) light on steel at wavelengths of 1 μm and 10 μm is shown as a function of the incident angle α. Clearly, at incident angles such as those encountered in laser cutting, the absorption is small, especially at a wavelength of 1 μm, and the absorption is always less than 40%. Particularly with increasing laser power, and especially when cutting very thick materials, only a significantly smaller fraction of the laser power (less than 10%) is absorbed. The remainder is reflected. According to the law of reflection and considering that the cutting front 53 is nearly vertical, the unabsorbed laser light propagates essentially downwards.

[0064] However, in practice, the theoretically optimal minimum angle of incidence will not appear. A typical cutting process is more similar to... Figure 4 The cutting process shown in the diagram involves a portion of the laser beam radiating downwards towards the bottom without interacting with the cutting front 53, and the incident angle α is even greater than α. 最小 This means that the energy efficiency available for the separation process is lower, and a higher proportion of the radiant energy radiates downward from the support area, in a vertical (i.e., radiation that does not interact with the workpiece) or nearly vertical (i.e., radiation reflected by the cutting front), so its direction is essentially vertical.

[0065] Figure 5The illustration shows a first embodiment of the invention. The laser cutting machine 1 has an energy harvesting device 50 at its base for collecting thermal laser energy. The thermal laser energy extracted by the energy harvesting device can be advantageously used either by direct recovery (as heat for direct heating or stored in a heat storage tank) or by conversion into electrical energy using a conversion device. In addition to the energy obtained, the machine base with a cooling device has the advantage of significantly less wear than in prior art laser cutting systems. Especially at laser power of 30 kW or greater, the wear on the machine base is considerable due to the thermal effect of the processed laser beam.

[0066] exist Figure 5 In one embodiment, the energy harvesting device 50 is connected to a heat exchanger, which can be further connected to a generator to produce electrical energy, as will be explained in more detail below. Figure 5 This shows a cross-section of a flatbed laser cutting machine commonly used today for laser cutting sheet metal.

[0067] A workpiece support is formed by a support grid 14. The support grid 14 is horizontally positioned below the laser cutting head 210, illustrated here, which has a nozzle 211 for injecting a jet of process gas onto the incident position of the laser beam on the workpiece 5. The machine base below the support grid includes a movable trolley 4 into which cutting waste falls. Unused laser power is absorbed by the machine base with the trolley 4. Figure 6 As schematically illustrated, according to the illustrated embodiment, the trolley is part of an energy harvesting device and can be supplied with a regenerative fluid. For this purpose, each trolley 4 forms a container for the regenerative fluid and includes an inlet 41 and an outlet 42 for the container, each of the inlet 41 and the outlet 42 being fluidly connected to a pipe.

[0068] During operation, a constant flow of regenerative fluids, particularly water, ensures that the heat generated by the trolley absorbing radiation is collected, removed, and made usable. The regenerative fluid can flow in an open system or in a closed regenerative fluid loop. If the heat is needed to generate electricity, these pipes can be directed to a heat exchanger, which is further connected to a generator to produce electricity. The generated electricity can be stored in batteries or fed directly into the power grid or the machine's power supply.

[0069] In embodiments with a trolley forming the base of the machine, regenerative fluid flows through the trolley. The pipes supplying and discharging the regenerative fluid to the trolley need to be long and flexible enough to allow for periodic removal of the trolley, as it will collect cutting waste that must be processed at regular intervals. For example, the machine may include a reel for the tubes to neatly store excess tube sections.

[0070] In another embodiment, the base of the laser machine is equipped with a conveyor belt for transporting cutting waste and dust. The advantage of a conveyor belt over a trolley is that the cutting waste does not need to be manually emptied.

[0071] Figure 7 A machine with a belt conveyor is schematically illustrated for conveying cutting waste from a container containing a regenerating fluid 72. A conveyor belt 71, having, for example, metal sections, is partially immersed in a bath of regenerating fluid 72. During laser cutting machine operation and / or between operating cycles, the conveyor belt can be activated to convey debris (cutting waste) from a container 73 containing the bath of regenerating fluid 72 and positioned below a support area; the container 73 forms part of the machine base. Figure 5 and Figure 6 In this implementation, the thermal energy transferred via the regenerating fluid can, for example, be used to generate electricity. The regenerating fluid can be directed to a heat exchanger, which is further connected to a generator to produce electricity. The generated electrical energy can be stored in a battery or fed directly into the power grid or the machine's power supply.

[0072] Reference Figure 8 A further embodiment is described. The machine includes a belt conveyor. The conveyor belt 71, cooled by a regenerating fluid, is... Figure 8 The image is shown in cross-section. The conveyor belt 71 is cooled from below only by the regenerating fluid 72, as the cooling fins 75 on the inner side of the conveyor belt 71 are driven through the regenerating fluid contained in the container 73. In this way, the conveyor belt 71 is well cooled; however, cutting waste does not fall into the regenerating fluid (e.g., water). The regenerating fluid inlet 41 and the regenerating fluid outlet 42 ensure constant cooling of the conveyor belt and removal of heat for use similar to the embodiments described above.

[0073] Reference Figure 8 The illustrated embodiment has the additional advantage of preventing cutting waste from falling into the regenerating fluid bath. The machine can include a housing that effectively protects the bath from any waste, dust, etc. This is consistent with... Figure 7 The implementation methods are different, in Figure 7 In this implementation, depending on the material being cut, the regenerating fluid may become heavily contaminated over time, and the coolant-dust mixture may contaminate all parts of the machine that come into contact with it.

[0074] Figure 9 This shows a further variation. Similar to... Figure 8 In this implementation, the conveyor belt 71 will move away from the support grid 14 (see...) Figure 5The workpiece support formed by the workpiece releases heat again to the regenerating fluid 72, for example by means of cooling fins 75, so that the regenerating fluid 72 does not come into contact with the cutting waste. The regenerating fluid 72 is contained in a container 73, which has a bottom that is a good thermal conductor—for example, at least the bottom of the container 73 can be a sheet metal or other relatively thin material with good thermal conductivity. A flat device 78 of a thermoelectric converter in the form of a Peltier element 77 (hereinafter referred to as a "Peltier element" for converting heat into electrical energy using the so-called Seebeck effect) is arranged directly below the container 73, and this flat device 78 is in thermal contact with the container 73. The container 73 constitutes the high-temperature side of the Peltier element 77, while the cooling structure ( Figure 9 (Not shown) forms the low-temperature side. A Peltier element is used to convert the heat energy absorbed by the regenerating fluid into electrical energy. The electrical energy is fed to the power storage device 80 via wire 79. Instead of being stored in the power storage device 80, the electrical energy can be directly fed to the power grid and / or reused directly by the laser cutting machine or other equipment.

[0075] Alternatively, the portion of thermal energy that cannot be converted into electrical energy may be used. For example, the cooling structure on the low-temperature side of the Peltier element 77 may include liquid cooling, wherein the heat absorbed by the appropriate cooling liquid (different from the regenerating fluid) may be used in the manner described above, for example, for heating purposes, for regeneration on the cold side of a heat pump device, etc.

[0076] More generally, the present invention covers any possibility of using thermal energy collected below the support area (particularly below or even through the workpiece support), including any possibility of converting thermal energy into electrical energy (meaning converting thermal energy into electrical energy within physical and practical limitations, and optionally using unavoidable waste heat collected on the cold side of the conversion device).

[0077] Figure 10 It shows that according to Figure 8 and 9 A variation of the implementation. A tortuous conduit 81 for the secondary regenerative fluid is arranged in the container 73, through which thermal energy is extracted from the regenerative fluid 72 in the container 73. The tortuous conduit 81 is connected to a generator unit 82, in which electrical energy is generated by thermal energy supplied, for example, via a steam turbine. This electrical energy is fed to an energy storage device 80 via a wire 79. Instead of the energy storage device 80, a direct grid connection can also be provided for feeding electrical energy into the grid. The energy storage device 80 can be connected to the power supply of the laser cutting system and deliver energy to that power supply.

[0078] Figure 11 It shows the combination of reference Figure 8 , Figure 9 and Figure 10 Another variation of the described implementation concept is that electrical energy can be generated by means of a Peltier element 77 and a generator 82. Figure 11 In this configuration, the pipeline 81 for the secondary regenerative fluid is arranged on the high-temperature side of the Peltier element 77, thus the Peltier element 77 and the generator 82 are supplied with heat in parallel. A series arrangement is also possible, in which the secondary regenerative fluid supplying heat to the generator 82 is used to cool the low-temperature side of the Peltier element 77, and / or in which the low-temperature side of the generator 82 (specifically: the low-temperature side of the generator's heat engine) is cooled via the Peltier element. In practice, the arrangement can be optimized based on the optimal processing temperature of the components involved.

[0079] Figure 12 Another embodiment is shown in the figure. Bridge-like member 202 (see also...) Figure 1 , Figure 5 It is connected to a movable collection structure in the form of a liquid delivery pipe 90.

[0080] exist Figure 13 The image shows a cross-section of the liquid delivery pipe 90. Unused downward-radiating laser radiation 3 is collected through the liquid delivery pipe 90, thereby generating heat. The liquid delivery pipe 90 can be oblong / elliptical in shape, allowing cuts, fallen portions, and cutting waste to fall to the bottom without adhering. Figure 14 An alternative shape for the liquid delivery tube 90, namely a triangle, is shown.

[0081] Figure 15 and Figure 16 Depicted respectively Figure 13 and Figure 14 A variation of the embodiment is provided, wherein the liquid delivery pipe 90 comprises a body 91 of a first material and a coating 92 of a second material, different from the first material, at least on its upper side. The first material may be a good thermal conductor and / or a material with considerable ductility that minimizes the possibility of pipe rupture. Examples of suitable first materials are copper, aluminum, steel, etc. The second material may be a highly heat-resistant material, such as ceramic.

[0082] Below the movable collection structure, the laser cutting machine can be equipped with a conveyor belt or trolley 4 for collecting and removing cutting waste.

[0083] The variation with a regenerative fluid delivery pipe that moves along with the bridge-like component offers the following advantages: the heat absorption unit is closer to the laser cutting head 210, allowing for the absorption of more energy and reducing the risk of damage if waste material falls from the cutting table. The overall system area is also smaller when the liquid delivery pipe moves with the bridge-like component. This makes it easier to bring the regenerative fluid to a high temperature, thereby enabling higher efficiency for heat engines or other power generation devices, since the Carnot efficiency, which sets the upper limit of achievable efficiency, depends on the temperature difference between the high-temperature and low-temperature sides. Furthermore, although virtually all residual radiation (see the explanation above) hits the energy harvesting structure, there is no direct contact between the regenerative fluid 72 on one side and the cutting waste on the other.

[0084] Figure 17 It shows the relationship with Figure 12 This embodiment is similar to the embodiment in which the liquid delivery pipe 90 serves as a movable collection structure. (And...) Figure 12 Unlike other implementations, the laser cutting machine also has a photosensitive panel 93, which is arranged to receive radiation reflected, especially diffusely reflected, from the surface of the (movable) collection structure.

[0085] Figure 17 The implementation of the type shown—which includes directly converting unused laser radiation into electrical energy—advantageously has the following structure: this structure distributes the unused laser radiation over a large area, such that... Figure 17 The intensity at the transition point on the photosensitive panel 93 will not be too high. This can be achieved, for example, by designing the surface of the collecting structure so that any reflection is diffuse, or by locally making the reflective surface partially concave or convex. By doing so, damage or destruction of the photosensitive panel 93 can be avoided.

[0086] Implementations that directly convert unused laser radiation into electrical energy can be further combined with measures to prevent the photosensitive panel from being splattered by the cutting material. For example, a barrier can be placed laterally below the processing area so that there is no direct path from the incident position of the laser beam on the workpiece to the photosensitive surface of the photosensitive panel on the other side, so that only reflected radiation reaches the photosensitive surface.

Claims

1. A method for cutting a metal workpiece, the method comprising providing a flatbed laser cutting machine (1) having a workpiece support defining a horizontal support area for a workpiece (5), the flatbed laser cutting machine further comprising a laser cutting head (210) disposed above the support area and configured to emit a laser cutting beam (3) toward the workpiece in addition to emitting a processing gas toward the workpiece while the workpiece is supported by the workpiece support, and configured to move horizontally relative to the workpiece (5) and the workpiece support, the method further comprising moving the laser cutting head relative to the workpiece while emitting the laser cutting beam (3) toward the workpiece (5) and blowing the processing gas toward the workpiece (5), characterized in that, The flatbed laser cutting machine (1) includes an energy harvesting device, which includes a harvesting structure below the support area and is configured to harvest the radiation energy of laser radiation that travels from the laser cutting head and is reflected by the cutting front surface area (53), wherein the energy harvesting device is configured to recover the radiation energy harvested by the harvesting structure.

2. The method according to claim 1, wherein, The energy harvesting device is configured to contact the regenerating fluid with the harvesting structure.

3. The method according to claim 2, wherein, The flatbed laser cutting machine is configured to transfer the regenerating fluid from the cooling structure to an energy recovery device, and / or wherein the flatbed laser cutting machine includes an energy recovery device in contact with the regenerating fluid.

4. The method according to claim 3, wherein, The energy recovery device includes a heat engine for converting the collected heat into mechanical energy and a generator for converting the mechanical energy into electrical energy.

5. The method according to claim 3 or 4, wherein, The energy recovery device includes a thermoelectric converter.

6. The method according to any one of claims 2 to 4, wherein the laser cutting machine includes a container (73) for the regenerating fluid, the container (73) being located below the support region.

7. The method according to any one of claims 2 to 4, wherein the laser cutting machine includes a belt conveyor forming at least a portion of the collection structure, the belt conveyor being configured to convey cutting waste away from the area below the support region.

8. The method according to claim 7, wherein, The upper surface of the conveyor belt (71) does not contact the regenerating fluid, and the conveyor belt (71) includes a thermal contact structure that is in thermal contact with the regenerating fluid.

9. The method according to any one of claims 1 to 4, further comprising a secondary regenerative fluid loop, wherein a heat exchanger is provided between the regenerative fluid and the secondary regenerative fluid of the secondary regenerative fluid loop.

10. The method according to any one of claims 1 to 4, wherein, The collecting structure is fixed and extends below the workpiece support, and the horizontal extension range of the collecting structure substantially corresponds to the horizontal extension range of the workpiece support.

11. The method according to any one of claims 1 to 4, wherein, The collection structure includes an open container.

12. The method according to any one of claims 2 to 4, wherein, The collection structure includes a movable collection structure configured to follow the movement of the laser cutting head.

13. The method according to claim 12, wherein, The flatbed laser cutting machine (1) includes a bridge-shaped member, on which the laser cutting head (210) is mounted, and the laser cutting head is movable relative to the bridge-shaped member along a first horizontal dimension (x), and the bridge-shaped member is movable relative to the workpiece support along a second horizontal dimension (y) different from the first horizontal dimension, wherein the movable collection structure is movable together with the bridge-shaped member (202) along the second horizontal dimension (y).

14. The method according to claim 12, wherein, The movable collection structure includes a liquid delivery pipe (90) for the regenerative fluid.

15. The method according to claim 14, wherein, The liquid delivery pipe has a cross-section that is not circular, wherein at least one of the following conditions is met: the cross-section tapers towards the upper side; and the horizontal dimension of the cross-section is smaller than the vertical dimension.

16. The method according to any one of claims 1 to 4, wherein, The energy harvesting device includes a photoelectric unit.

17. The method according to any one of claims 1 to 4, wherein, The laser cutting head (210) is configured to emit the laser cutting beam (3) in a vertically downward direction.

18. The method according to any one of claims 1 to 4, wherein, The laser cutting head (210) is configured to move along at least two horizontal directions (x, y) while the laser cutting beam (3) is emitted downward toward the workpiece (5) and while the processing gas is blown toward the workpiece.

19. The method according to any one of claims 1 to 4, wherein, The workpiece (5) is a metal sheet or metal plate and extends horizontally on a workpiece support, wherein the laser cutting beam (3) is emitted vertically and incident on the workpiece perpendicular to the surface of the workpiece, and the collecting structure is located vertically below the incident position of the laser cutting beam on the workpiece, and the processing gas is sprayed onto the incident position of the laser cutting beam on the workpiece (5).

20. The method according to any one of claims 1 to 4, wherein, The workpiece support is formed by a support grid (14), and the collection structure is located below the workpiece support.

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