Water jet laser processing machine

Abstract

A water jet laser processing machine (100) comprises a nozzle (26), a pump (40), a pressure sensor (42), a storage unit (52) and a determination unit (51), wherein the nozzle (26) is configured to spray a water column (34) and can guide a laser beam into the water column (34); the pump (40) supplies pressurized water to the nozzle (26); the pressure sensor (42) detects the pressure of the water supplied from the pump (40) to the nozzle (26); the storage unit (52) stores a threshold value for determining whether the pressure of the water supplied from the pump (40) to the nozzle (26) has decreased; and the determination unit (51) determines whether the pressure detected by the pressure sensor (42) has decreased based on the pressure detected by the pressure sensor (42) and the threshold value stored in the storage unit (52), thereby determining whether the nozzle (26) is damaged.

Description

Technical Field

[0001] The invention relates to a water jet laser processing machine. Background Art

[0002] Conventionally, a water jet laser processing machine that processes a workpiece by irradiating a laser beam guided by a water column to the workpiece has been known. In such a water jet laser processing machine, if a nozzle for irradiating the water column is damaged, the water column may be improperly formed. In this case, the laser beam cannot be guided as expected, and therefore, the workpiece may not be properly processed.

[0003] Regarding the above-mentioned problem, for example, Patent Document 1 discloses a laser processing device having a detection component for detecting an abnormality of a liquid column. This laser processing device has a tube for passing a liquid column that guides a laser beam. Furthermore, the tube is constructed in a manner to allow a gas to pass through the liquid column so as to flow around the liquid column and rectify the liquid column. The detection component has various sensors (for example, a flow sensor, an acoustic sensor, and a pressure sensor) for detecting an abnormality of the above-mentioned gas. These sensors are arranged on the periphery of the nozzle on a flow path for guiding the gas into the tube. In this laser processing device, the abnormality of the gas detected by these sensors is identified as an abnormality of the liquid column.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-215769 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In the laser processing device of Patent Document 1, various sensors are provided around the nozzle as described above, and therefore, additional structural elements including their wiring are required, and there is a possibility that the design around the nozzle becomes complicated. The present disclosure aims to provide a water jet laser processing machine that can detect nozzle damage with a simpler structure.

[0009] Means to solve the problem

[0010] The present invention discloses a hydraulic jet laser processing machine, which processes a workpiece by guiding a laser beam through a water column and irradiating the laser beam relative to the workpiece. The machine is characterized in that it comprises a nozzle, a pump, a pressure sensor, a storage unit and a determination unit, wherein the nozzle is configured to spray the water column and guide the laser beam into the water column; the pump supplies pressurized water to the nozzle; the pressure sensor detects the pressure of the water supplied from the pump to the nozzle; the storage unit stores a threshold value for judging a decrease in the pressure of the water supplied from the pump to the nozzle; and the determination unit determines whether the pressure detected by the pressure sensor has decreased based on the pressure detected by the pressure sensor and the threshold value stored in the storage unit, thereby determining whether the nozzle is damaged.

[0011] The inventors have made careful studies and found that when the nozzle is damaged (e.g., cracked), the pressure of the water supplied from the pump to the nozzle is reduced. Therefore, by arranging a pressure sensor between the pump and the nozzle in a manner that detects the pressure of the water, it is possible to detect a reduction in the pressure of the water supplied from the pump to the nozzle, that is, damage to the nozzle. Therefore, it is possible to easily determine whether the nozzle is damaged by a simple structure including a pressure sensor between the pump and the nozzle.

[0012] Alternatively, the storage unit further stores the relationship between the pressure of the water supplied from the pump to the nozzle and the length of the laminar layer of the water column. When the determination unit determines that the nozzle is damaged, the determination unit calculates the length of the laminar layer based on the pressure detected by the pressure sensor and the relationship stored in the storage unit, and further determines whether the workpiece can be processed by determining whether the length of the laminar layer is longer than the desired processing depth. The inventors have also found that there is a correlation between the pressure of the water supplied from the pump to the nozzle and the length of the laminar layer of the water column. Therefore, according to this method, even when the nozzle is damaged, it is possible to determine whether the damaged nozzle can be used to process the workpiece by calculating the length of the laminar layer. Therefore, the use period of the nozzle can be extended.

[0013] Alternatively, the storage unit may store the pressure detected by the pressure sensor at a certain time as the threshold value, and the determination unit may determine that the pressure detected by the pressure sensor has decreased when the pressure detected by the pressure sensor has been lower than the threshold value for a predetermined time or longer after the certain time. According to this mode, even when the pressure detected by the pressure sensor changes slightly, the decrease in pressure can be accurately detected, and therefore, whether the nozzle is damaged can be more accurately determined.

[0014] Effects of the Invention

[0015] According to one aspect of the present disclosure, it is possible to provide a water jet laser processing machine capable of detecting damage to a nozzle with a simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram showing a water jet laser processing machine related to the embodiment.

[0017] Figure 2 Yes means Figure 1 Flow chart of the operation of the water jet laser processing machine. DETAILED DESCRIPTION

[0018] Modes for carrying out the invention

[0019] Hereinafter, the fluid supply device and the water jet laser processing machine according to the embodiment will be described with reference to the accompanying drawings. The same reference numerals are given to the same or corresponding elements, and repeated descriptions are omitted. For ease of understanding, the scale of the drawings may be changed.

[0020] Figure 1 1 is a schematic diagram showing a water jet laser processing machine 100 according to an embodiment. The water jet laser processing machine (hereinafter, simply referred to as a "laser processing machine") 100 guides a laser beam by a water column 34 and processes a workpiece W by irradiating the workpiece W with the laser beam. The laser processing machine 100 includes, for example, a laser head 10, a pure water production device 30, a high-pressure pump 40, a pulsation damper 41, a pressure sensor 42, a workpiece table 36, and a control device 50. The laser processing machine 100 may also include other structural elements.

[0021] The laser head 10 irradiates a laser beam relative to the workpiece W. For example, the laser head 10 can be linearly moved relative to the workpiece table 36 in each of the three orthogonal axial directions (X, Y and Z directions). The movement of the laser head 10 can also be controlled by, for example, an NC device assembled in the control device 50. In the laser head 10, a laser beam is emitted from a laser oscillator 14 arranged outside (or inside) the housing 12. For example, the laser oscillator 14 emits a visible light laser (for example, Nd:YAG (yttrium aluminum garnet crystal) laser). The laser beam is received by the laser irradiation head 16 via a light-guiding component 14a such as an optical fiber. The laser irradiation head 16 irradiates a laser beam toward a collimating lens 18. The laser beam from the laser irradiation head 16 is converted into parallel light by the collimating lens 18, reflected by the first reflector 20 toward the second reflector 22, and reflected by the second reflector 22 toward the laser focusing lens 24. The laser beam focused by the laser focusing lens 24 is irradiated toward the outside of the housing 12 through the nozzle hole 26 b of the nozzle 26 .

[0022] The first and second reflectors 20 and 22 have planar reflective surfaces, and have a first motor 20a and a second motor 22a as reflector arrangement direction change components, respectively. By adjusting the arrangement direction of the reflective surfaces by the first motor 20a and the second motor 22a, the focal position of the laser beam can be adjusted to two horizontal directions (X direction and Y direction). For example, the first and second reflectors 20 and 22, especially the second reflector 22 that reflects the laser beam toward the laser focusing lens 24, may also include an inductor multilayer film. The inductor multilayer film is adapted to the wavelength of the laser beam irradiated from the laser oscillator 14, reflects the laser beam, and transmits light of wavelengths other than the wavelength of the laser beam. Such an inductor multilayer film is formed on a glass plate by, for example, vapor deposition. When the second reflector 22 includes the inductor multilayer film, the positional relationship between the laser beam irradiated from the nozzle hole 26b and the nozzle hole 26b can be monitored by the camera 32. For example, the focus of the camera 32 is aligned with the surface of the nozzle head 26a at the same height as the opening surface of the nozzle hole 26b. The operation of the components of the laser head 10 (eg, the laser oscillator 14 , the first motor 20 a , the second motor 22 a , and the camera 32 ) can be controlled by, for example, a mechanical control device incorporated in the control device 50 .

[0023] The nozzle 26 sprays a water column 34 and irradiates a laser beam into the water column 34. Specifically, the nozzle 26 has a nozzle head 26a. The nozzle head 26a is a hollow member that receives water supply from a high-pressure pump 40 through a pipe 28. A window 26c formed of a transparent member such as glass is provided on the upper surface of the nozzle head 26a facing the laser focusing lens 24. A nozzle hole 26b is provided on the nozzle head 26a. A nozzle body (not shown) that is separate from the nozzle head 26a can also be detachably mounted on the nozzle head 26a, and the nozzle hole 26b can also be provided on this nozzle body. In this case, one nozzle body can be selected from a plurality of nozzle bodies having nozzle holes 26b of different inner diameters according to processing conditions. With such a structure, the inner diameter of the nozzle 26 can be changed. The pressure of the water column 34 changes according to the flow rate of water and the inner diameter of the nozzle hole 26b. For example, when the water flow rate is 20 ml / min to 150 ml / min and the inner diameter of the nozzle hole 26b is 30 μm to 135 μm, the pressure of the water column 34 is approximately 50 MPa (500 bar) to 5 MPa (50 bar). The laser beam irradiated from the nozzle hole 26b to the outside of the housing 12 is surrounded by the water column 34 and advances while being totally reflected at the interface between the water column 34 and the surrounding air. Therefore, the laser beam advances along the water column 34.

[0024] The pure water production device 30 produces water (e.g., pure water or ultrapure water with less impurities than pure water) used to form the water column 34. The pure water production device 30 is fluidically connected to a water supply source 60 (e.g., tap water) and can include structural elements such as a tank, a pump, and a filter.

[0025] The high-pressure pump 40 pressurizes the water supplied from the pure water production device 30, and supplies the pressurized water to the nozzle 26 through the pulsation damper 41 and the pipeline 28. The high-pressure pump 40, for example, can be an air-driven diaphragm pump. In other embodiments, the high-pressure pump 40 can also be other types of positive displacement pumps (for example, rotary or reciprocating).

[0026] The pulsation damper 41 is configured to remove the pulsation of the pressurized water sent from the high-pressure pump 40. The pulsation of the pressurized water may affect the processing quality. Therefore, the pulsation is removed from the pressurized water before the pressurized water is supplied to the nozzle 26. When the high-pressure pump 40 is a type of pump that does not generate pulsation, the pulsation damper 41 may not be provided.

[0027] The pressure sensor 42 is configured to detect the pressure of water supplied from the high-pressure pump 40 to the nozzle 26. For example, the pressure sensor 42 can be connected to the flow path between the high-pressure pump 40 and the nozzle 26 (in this embodiment, between the pulsation damper 41 and the nozzle 26). The pressure sensor 42 can communicate with the control device 50 by wire or wirelessly, and is configured to transmit the detected pressure to the control device 50.

[0028] The work table 36 is, for example, disposed on a bed (not shown) and holds the workpiece W. The work table 36 may also include a feeding device such as a rotating mechanism (not shown). The operation of the work table 36 may be controlled by, for example, an NC device incorporated in the control device 50 .

[0029] The control device 50 is connected to various components of the laser processing machine 100 by wire or wireless, and is configured to control these components. The control device 50 may be, for example, a personal computer, a server, a tablet computer, etc. The control device 50 may include, for example, a determination unit 51, a storage unit 52, and a display unit 53. The control device 50 may include other components (e.g., ROM (read-only memory) and / or input devices (e.g., a mouse, a keyboard, and / or a touch panel)). The components of the control device 50 may be connected to each other via a bus (not shown) or the like.

[0030] The determination unit 51 can be realized by, for example, a program stored in the storage unit 52, and the determination unit 51 processing can be executed by, for example, a processor such as a CPU (central processing unit). The determination unit 51 is configured to determine whether the nozzle 26 has damage based on the decrease in pressure detected by the pressure sensor 42.

[0031] Specifically, as the nozzle 26, damage may occur due to various reasons (for example, collision of debris with the nozzle, irradiation of the laser beam with the nozzle due to poor alignment adjustment of the laser beam, and / or long-term pressure on the nozzle caused by high-pressure water delivered from the pump). Typically, there is a situation where tiny cracks are generated around the nozzle hole 26b due to the above-mentioned reasons. The inventors have found that as the size of such cracks increases and / or as the number of cracks increases, the pressure of the water delivered from the high-pressure pump 40 to the nozzle 26 decreases. Therefore, it is possible to determine whether the nozzle 26 includes damage based on the pressure drop detected by the pressure sensor 42. The inventors have also found that there is a correlation between the pressure of the water supplied from the high-pressure pump 40 to the nozzle 26 and the length of the laminar layer. In the present disclosure, "the length of the laminar layer" may refer to the length of the portion of the water column 34 where the streamline is a regular shape. Specifically, if the pressure of the water decreases, the length of the laminar layer also becomes shorter. Therefore, the length of the laminar layer can be predicted based on the pressure detected by the pressure sensor 42.

[0032] The storage unit 52 can include, for example, a hard disk drive and / or a RAM (random access memory). The storage unit 52 can store, for example, various programs executed by the processor. The storage unit 52 is configured to store the pressure detected by the pressure sensor 42. In addition, the storage unit 52 stores the relationship between the pressure of the water supplied from the high-pressure pump 40 to the nozzle 26 and the length of the laminar layer of the water column 34. The specific relationship between the pressure and the length of the laminar layer can be obtained by, for example, experimenting with the diameter of each nozzle hole 26b. The storage unit 52 can also store various other data.

[0033] The display unit 53 may be, for example, a liquid crystal display or a touch panel, etc. The display unit 53 can display a notification when, for example, the nozzle 26 is damaged or the workpiece W cannot be processed (details will be described later).

[0034] The control device 50 may be connected to the smartphone 401 and / or tablet computer 402 of the user of the laser processing machine 100 via a network N such as the Internet, for example. The control device 50 may be configured to send notifications (described later in detail) of the nozzle 26 being damaged and / or the processing being stopped to the user via the network N. With such a configuration, the operator can quickly learn of the problem.

[0035] Next, the operation of the water jet laser processing machine 100 will be described.

[0036] Figure 2 Yes means Figure 1 Flow chart of the operation of the water jet laser processing machine. Figure 2The operations shown can be started, for example, when machining is started according to a program stored in the storage unit 52 . Figure 2 The action shown may also be started according to the input from the operator, or may be started at other times. If the action is started, the determination unit 51 clears the count to n=0 (n=1, 2, 3, ...) (step S100). Next, the determination unit 51 stores the current pressure sent from the pressure sensor 42 in the storage unit 52 as a threshold for determining a decrease in pressure (step S102). Next, the determination unit 51 determines whether the processing is completed (step S104). In step S104, if it is determined that the processing is completed, a series of actions are completed.

[0037] In step S104, when it is determined that the processing is not completed, the determination unit 51 determines whether there is a malfunction in the high-pressure pump 40 (step S106). For example, the storage unit 52 may pre-store a specified lower limit pressure obtained by experiments or analysis, and in step S106, the determination unit 51 may determine whether the current pressure sent from the pressure sensor 42 is lower than the lower limit pressure stored in the storage unit 52. When the current pressure is lower than the lower limit pressure, the determination unit 51 may determine that there is a malfunction in the high-pressure pump 40, and when the current pressure is above the lower limit pressure, the determination unit 51 may determine that there is no malfunction in the high-pressure pump 40. The determination of step S106 may also be performed according to other methods.

[0038] In step S106, if it is determined that there is a malfunction in the high-pressure pump 40, the determination unit 51 notifies the malfunction (step S124), stops the processing (step S122), and ends a series of operations. The notification may be performed by displaying information on the display unit 53 or by sounding a warning sound from a speaker.

[0039] In step S104, when it is determined that there is no malfunction in the high-pressure pump 40, the determination unit 51 waits for a predetermined time (for example, at least 1 second) (step S108). Next, the determination unit 51 determines whether the current pressure sent from the pressure sensor 42 is lower than the threshold value (pressure at the time of step S102) stored in the storage unit 52 in step S102 (step S110).

[0040] In step S110 , when it is determined that the current pressure is not lower than the stored threshold, the determination unit 51 determines that the nozzle 26 is not damaged or the damage has not progressed, and repeats steps S100 to S110 until it is determined in step S104 that the processing is completed.

[0041] In step S110, when it is determined that the current pressure is lower than the stored threshold value, the determination unit 51 determines whether the count is within a specified range (for example, n≦10) (step S112). In step S112, when it is determined that the count is within the specified range, the determination unit 51 adds 1 to the count n (step S114), and repeats steps S104 to S112.

[0042] In step S112, when it is determined that the count is not within the prescribed range (i.e., when the pressure detected by the pressure sensor 42 is lower than the threshold value stored in the storage unit 52 for a prescribed time or longer), the determination unit 51 determines that the nozzle 26 is damaged, and notifies the operator that the nozzle 26 is damaged (step S116). The notification may be performed by displaying information on the display unit 53 or by sounding a warning sound from a speaker.

[0043] Next, the determination unit 51 calculates the length of the laminar layer based on the current pressure sent from the pressure sensor 42 and the relationship between the pressure and the length of the laminar layer stored in the storage unit 52 (step S118). Next, the determination unit 51 determines whether the calculated length of the laminar layer is longer than the desired processing depth (step S120).

[0044] In step S120 , when it is determined that the length of the laminar layer is longer than the processing depth, the determination unit 51 determines that the processing can be continued, and repeats steps S100 to S118 until it is determined in step S104 that the processing is completed.

[0045] In step S120, when it is determined that the length of the laminar layer is not longer than the processing depth, the determination unit 51 determines that it is difficult to continue the processing, stops the processing (step S122), and ends a series of operations. The determination unit 51, for example, disconnects the high-pressure pump 40 and the laser oscillator 14. In addition, the determination unit 51, for example, may also notify the operator of the stop of the processing. The notification may be performed by displaying information on the display unit 53 or by sounding a sound or warning sound from a speaker.

[0046] In the laser processing machine 100 according to the above-described embodiment, by arranging the pressure sensor 42 between the high-pressure pump 40 and the nozzle 26 so as to detect the pressure of water, it is possible to detect a decrease in the pressure of water supplied from the high-pressure pump 40 to the nozzle 26, that is, damage to the nozzle 26. Therefore, it is possible to easily determine whether the nozzle 26 is damaged by a simple configuration in which the pressure sensor 42 is provided between the high-pressure pump 40 and the nozzle 26.

[0047] In addition, in the laser processing machine 100, the storage unit 52 stores the relationship between the pressure of the water supplied from the high-pressure pump 40 to the nozzle 26 and the length of the laminar layer of the water column 34. When the determination unit 51 determines that the nozzle 26 includes damage, it calculates the length of the laminar layer based on the pressure detected by the pressure sensor 42 and the relationship stored in the storage unit 52, and further determines whether the workpiece W can be processed by determining whether the length of the laminar layer is longer than the desired processing depth. Therefore, even when the nozzle 26 includes damage, it can be determined by calculating the length of the laminar layer whether the workpiece W can be processed using the nozzle 26 including the damage. Therefore, the use period of the nozzle 26 can be extended.

[0048] In addition, in the laser processing machine 100, the storage unit 52 stores the pressure detected by the pressure sensor 42 at a certain time as a threshold value, and the determination unit 51 determines that the pressure detected by the pressure sensor 42 has decreased when the pressure detected by the pressure sensor 42 has been lower than the threshold value for a predetermined time or more after the time. Therefore, even when the pressure detected by the pressure sensor 42 changes slightly, the pressure decrease can be accurately detected, and therefore, it can be accurately determined whether the nozzle 26 is damaged. Here, the certain time refers to the time when the nozzle 26 is determined to be in a state where the processing can be performed when it is confirmed that the nozzle 26 is replaced with a new one or the length of the laminar layer of the water column 34 is longer than the desired processing depth.

[0049] The embodiment of the water jet laser processing machine has been described, but the present invention is not limited to the above embodiment. A person skilled in the art can make various modifications to the above embodiment. In addition, a person skilled in the art can understand that the steps executed by the control device 50 (or the determination unit 51) do not need to be implemented in the above order, and can be implemented in other orders as long as no contradiction occurs.

[0050] For example, in the above-mentioned embodiment, the storage unit 52 stores the pressure detected by the pressure sensor 42 at a certain time as a threshold value (step S102), and thereafter, when the pressure detected by the pressure sensor 42 is lower than the threshold value stored in step S102 for a predetermined time or more, the determination unit 51 determines that the pressure has decreased. In other embodiments, for example, the storage unit 52 may also store a predetermined threshold value obtained by experiments or analysis in advance, and the determination unit 51 may also determine that the pressure has decreased when the pressure detected by the pressure sensor 42 is lower than the stored threshold value. In this case, for example, the predetermined threshold value may be a value higher than the lower limit pressure used when determining the malfunction of the high-pressure pump 40.

[0051] Explanation of symbols

[0052] 26: Nozzle

[0053] 34: Water Column

[0054] 40: Pump

[0055] 42: Pressure sensor

[0056] 51: Judgment Department

[0057] 52: Storage

[0058] 100:Hydraulic jet laser processing machine

[0059] W: workpiece.

Claims

1. A water jet laser processing machine, which processes a workpiece by guiding a laser beam with a water column and irradiating the laser beam to the workpiece, characterized in that: It is equipped with a nozzle, a pump, a pressure sensor, a storage unit and a determination unit. The nozzle is configured to spray the water column and direct the laser beam into the water column; The pump supplies pressurized water to the nozzles; The pressure sensor detects the pressure of water supplied from the pump to the nozzle; The storage unit stores a threshold value for determining a decrease in the pressure of water supplied from the pump to the nozzle; and the relationship between the pressure of water supplied from the pump to the nozzle and the length of the laminar layer of the water column; During processing, the determination unit determines whether the pressure detected by the pressure sensor has decreased based on the pressure detected by the pressure sensor and the threshold value stored in the storage unit, thereby determining whether the nozzle is damaged. If it is determined that the nozzle is damaged, the length of the laminar layer is calculated based on the pressure detected by the pressure sensor and the above relationship stored in the storage unit, and further determines whether the length of the laminar layer is longer than the expected processing depth. If it is determined that the length of the laminar layer is longer than the expected processing depth, the processing is continued, and if it is determined that the length of the laminar layer is not longer than the expected processing depth, the processing is stopped.

2. The water jet laser processing machine according to claim 1, characterized in that: The storage unit stores the pressure detected by the pressure sensor at a certain moment as the threshold value. The determination unit determines that the pressure detected by the pressure sensor has decreased when the pressure detected by the pressure sensor is lower than the threshold value for a predetermined time or longer after the certain time point.

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