JP6348877B2 - Thermal cutting apparatus and method - Google Patents

Description

  The present invention is based on a thermal cutting method for cutting a workpiece by applying thermal energy to the workpiece, for example, by laser irradiation, plasma arc discharge, heat of oxidation reaction by high pressure oxygen ejected from a gas cutting nozzle. The present invention relates to a thermal cutting apparatus and method for processing and cutting, and more particularly, to a thermal cutting apparatus and method for removing a molten product (hereinafter referred to as dross) generated by laser irradiation and plasma arc discharge.

  Conventionally, a thermal cutting technique by applying thermal energy for processing / cutting a workpiece has been proposed. For example, processing performed while removing molten products (hereinafter referred to as dross) generated when performing thermal cutting such as laser irradiation, plasma arc discharge, or oxidation reaction heat generated by high-pressure oxygen ejected from a gas cutting nozzle. -Cutting technology has been proposed.

  For example, Patent Document 1 discloses that in a combined laser and water jet machining apparatus including a laser head 1 and a water jet head 2 that perform laser beam irradiation and water jet injection separately and independently, the laser head 1 The apparatus further includes intermittent injection control means for controlling the water jet from the water jet head 2 to be intermittently injected into the melted portion of the workpiece by the laser beam of "." .

  Further, Patent Document 2 discloses "cutting by irradiating an object to be cut with laser light and melting it, and jetting and removing the melted portion with high-pressure water." In this case, the cutting part is irradiated with a laser beam to be melted, and the melting part is blown off with a water jet for cutting. That is, “the kinetic energy of the high-pressure water is larger and the high-pressure water itself has the cutting ability than the conventional method of blowing the melted portion with gas, so that the cutting ability is increased and the thick plate can be cut. Since no oxygen gas is used, there is no risk of fire, and even when melted with laser light, high pressure water is injected so there is no risk of burning even when used for FRP cutting, and the cutting speed is as fast as conventional laser cutting. It can be cut. "

JP 2001-62652 A JP-A-11-774

  Patent Document 1 and Patent Document 2 describe that a workpiece is not particularly limited, and laser irradiation is performed for processing and cutting a wide range of objects. However, in this regard, these are more specific workpieces, for example, nuclear fuel, high atmospheric dose nuclear power plants, reprocessing plants, decommissioning of decommissioned nuclear power plants, etc. As another example, the reactor fuel melts due to the loss of coolant at the Fukushima Daiichi Nuclear Power Station, and cools and hardens together with the reactor structural materials and control rods. It is not intended for work.

  Patent Document 1 and Patent Document 2 describe the use of a water jet in order to blow off a product (dross) generated during laser cutting or to further increase the cutting force. However, in this regard, in Patent Document 1, the reason why the water jet is used instead of the gas jet is that oxygen may be ignited when the gas jet is used.

  Moreover, in patent document 1, although it is supposed that a water jet is used intermittently, the method and conditions of a specific intermittent injection are not disclosed.

  In short, Patent Document 1 and Patent Document 2 specifically describe how laser processing / cutting should be performed when the workpiece is “activated steel” or “fuel debris”. Not shown. In order to target activated steel and fuel debris, it is necessary to fully consider the environment in which the activated steel and fuel debris are placed. Specifically, when water is used by a water jet, it should be noted that there is a concern that if it is used in a thermal decomposition or high-dose location, hydrogen is generated due to the decomposition and the risk of hydrogen explosion increases. It is.

  Accordingly, an object of the present invention is to provide a thermal cutting apparatus and method having a dross treatment method that changes to oxygen and water injection.

  In view of the above, in the present invention, a thermal cutting apparatus that applies thermal energy to a workpiece to cut and process the workpiece, the thermal energy applying means for applying thermal energy to the workpiece, and the dross generated on the workpiece. An inert material injection means for injecting and removing the inert material, a monitoring means for monitoring a melted portion that is a dross region generated on the workpiece, a thermal energy applying means, and an inert material injection means. A thermal cutting apparatus comprising control means for controlling and executing intermittent control by determining the injection timing of the inert substance by the inert substance injection means using information from the monitoring means.

  In addition, the present invention cuts and processes the workpiece by applying thermal energy, and injects and removes the inert material on the dross generated on the workpiece by the thermal energy, thereby removing the dross generated on the workpiece. It is a thermal cutting method characterized in that intermittent control is executed by determining the injection timing of the inactive substance using information on the melted part which is a region.

  ADVANTAGE OF THE INVENTION According to this invention, the thermal cutting apparatus and method provided with the dross process method changed into oxygen and water injection can be provided.

The figure which shows the structure of the laser processing and cutting apparatus which concerns on Example 1 of this invention. The figure which shows the relationship between temperature and a viscosity coefficient in case the to-be-processed object 8 is a ferrous material. The figure which shows the structure of the plasma processing and cutting apparatus which concerns on Example 1 of this invention. The flowchart which shows the processing content of the control apparatus 10 which concerns on Example 1 of this invention. The figure which shows the structure of the laser processing and cutting apparatus which concerns on Example 2 and Example 3 of this invention. The figure which shows the structure of the plasma processing and cutting apparatus which concerns on Example 2 and Example 3 of this invention. The flowchart which shows the processing content of the control apparatus 10 which concerns on Example 3 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the following is only an Example, and it cannot be overemphasized that the content of invention is not limited to the following aspect.

  FIG. 1 shows a configuration of a laser processing / cutting device as an example of a thermal cutting method for cutting a workpiece by applying thermal energy to the workpiece according to the present invention. The processing / cutting apparatus of the present invention includes laser irradiation means and inert body injection means. Whereas Patent Document 1 and Patent Document 2 are combined laser and water jet processing devices, in the present invention, a processing device using a laser and an inert material is used. In Patent Document 1 and Patent Document 2, the water jet can also contribute to the processing / cutting. However, in the present invention, the processing / cutting is a means for thermal cutting that performs processing / cutting by applying thermal energy. Specialized in, for example, lasers, etc. The inert material is blown away by the dross and cooled while being blown away to make it a mass that is easy to handle, so that it is re-welded to the object so as not to adversely affect cutting and processing. Specialized in processing dross after cutting and processing. Examples of the inert substance include liquid nitrogen, dry ice, and argon gas.

  The laser processing / cutting apparatus, which is an example of the thermal cutting / processing apparatus according to the present invention shown in FIG. 1, includes a laser irradiation means R, an inert material injection means K, and a monitoring means M.

  Among them, the laser irradiation means R is composed of a laser oscillator 5, a lens 2, a laser head 1, and the like, and the laser beam focused along the planned cutting line of the workpiece (cutting target portion) 8 is processed ( Irradiate the cutting target part) 8 to perform processing / cutting. The laser beam output from the laser oscillator 5 is sent to the laser head 1 disposed perpendicularly to the workpiece 8 through an optical fiber, and the workpiece 8 is formed by the lens 2 provided in the laser head 1. The processed part is focused and irradiated. The configuration of the laser head 1 is merely an example, and any combination of the optical system means provided in the laser head 1 may be used as long as the laser beam can be condensed and irradiated onto the workpiece 8. In the present invention, the function of processing / cutting is exclusively left to the laser irradiation means R.

  For example, in the case where liquid nitrogen is used as the inert substance, the inert body injection means K guides the liquid nitrogen in the liquid nitrogen tank 6 to the liquid nitrogen injection nozzle 3, and performs processing / cutting in the processing portion of the workpiece 8. Blow off the product (dross) produced by In the present invention, the liquid nitrogen injection timing is intermittently controlled according to information from the monitoring means M described later. For this reason, the liquid nitrogen injection nozzle 3 includes a valve mechanism for intermittent control. In the present invention, liquid nitrogen is used only for blowing dross and is not expected as power for processing and cutting. Thus, the pressurized liquid nitrogen pressurized in the liquid nitrogen tank 6 is sent to the liquid nitrogen injection nozzle 3 disposed in the vicinity of the periphery of the laser head 1 via the high-pressure hose, and is a valve for intermittent control. The timing and amount of liquid nitrogen controlled by the opening / closing control of the mechanism is intermittently injected toward the melting portion of the workpiece 8.

  The timing and amount of intermittent control of liquid nitrogen are determined based on the monitoring result of the monitoring means M. In the case of the embodiment of FIG. 1, the monitoring means M is composed of a temperature sensor 4 and a signal converter 7. In short, the monitoring means M detects the temperature of the work piece 8 at the melted part of the work piece 8 or the work part. Yes. Various methods can be applied to temperature detection, and any method for realizing the temperature detection is not limited in the present invention.

  In FIG. 1, the control device 10 executes a series of laser processing / cutting processes. For example, in relation to the laser irradiation means R, the workpiece (cutting target portion) 8 is irradiated with the laser light focused along the planned cutting line of the workpiece (cutting target portion) 8 to process / cut. To do.

  In the above description, as an example of a thermal cutting method for cutting a workpiece by applying thermal energy to the workpiece, the configuration of the laser processing / cutting device has been shown. Even in the case of thermal cutting such as oxidation reaction heat by high-pressure oxygen ejected from a gas cutting nozzle, it can be configured in the same manner as in the case of a laser. In the present invention, the thermal cutting method may be based on any one of the above or other principles.

  FIG. 3 shows a configuration of a plasma processing / cutting apparatus as an example of a thermal cutting method for cutting a workpiece by applying thermal energy to the workpiece according to the present invention. The plasma processing / cutting apparatus shown in FIG. 3 differs from that shown in FIG. 1 only in that the plasma arc generating means P shown in FIG. The plasma arc generating means P is composed of an electrode 11 and a plasma head 12, and cuts the object by applying thermal energy to the object by the generated plasma.

  In the present invention, as the portion to be cut by thermal energy, those of various principles can be adopted as described above. Therefore, in the following description, arc cutting will be described unless otherwise specified.

  Regarding the dross processing according to the present invention, a series of processing is executed along the processing flow shown in FIG. According to the processing flow of FIG. 4, a series of processing processes is started in the first processing step S1. The treatment process includes a laser irradiation process. In the next processing step S2, temperature measurement preparation processing for obtaining temperature information through the temperature sensor 4 and the signal converter 7 of the monitoring means M is performed. If the measurement is possible, the laser irradiation means R is driven to process / cut the workpiece (cutting target portion) 8 in the next processing step S3.

  In the monitoring means M, temperature information is continuously obtained through the temperature sensor 4 and the signal converter 7. In processing step S4, it is determined whether the measured temperature is equal to or higher than a threshold value. FIG. 2 shows the relationship between temperature and viscosity coefficient when the workpiece 8 is an iron-based material. According to this, the viscosity of iron oxide FeO decreases as the temperature increases. Therefore, in Example 1 of the present invention, it is determined from the measured temperature of the melted part that the viscosity coefficient is lower than a predetermined value. If the viscosity coefficient is lower than the predetermined value, the dross can be easily blown off, but if the viscosity coefficient is higher than the predetermined value, the effect of blowing off cannot be expected.

  Note that FIG. 2 shows that when the temperature is low, iron oxide FeO has a lower viscosity than iron Fe, but when the temperature becomes higher than a certain temperature, the viscosity is reversed and the fluidity of iron oxide FeO becomes extremely good. This means that when oxygen gas is blown and cut, it becomes dross-free (a state in which no dross is attached).

  When the temperature measured in the processing step S4 is equal to or higher than the threshold value, it is considered that the blow-off can be effectively performed. Therefore, in the processing step S5, the inert body injection means K is driven, and the dross removing process by the liquid nitrogen injection is performed. To implement.

  When the temperature measured in the process step S4 is equal to or lower than the threshold value, it is considered that the blow-off cannot be performed effectively. .

  The above heating and blow-off processing is continuously executed while shifting the work position as appropriate until the processing / cutting work of the work piece (cutting target part) 8 planned in advance is completed. It becomes.

  Thus, according to the above procedure, first, the workpiece 8 is continuously irradiated with laser light from the laser head 1 to melt the workpiece 8 (melting step). The dross melted by the laser beam 12 is generated and the temperature has risen to a sufficient temperature, so that it is estimated that effective blowing is possible, and liquid nitrogen is jetted to blow off the dross in the melted portion. Do (removal step) Due to the cooling effect of liquid nitrogen, the blown-out dross becomes an easy-to-handle lump, and the adverse effect of re-welding can be prevented. After removing the dross from the melted part, the liquid nitrogen jet from the liquid nitrogen jet nozzle 3 is stopped, and the workpiece 8 is irradiated with only the laser beam to form the melted part. Also, the newly formed molten portion dross is blown off by being again sprayed onto the processing portion by the liquid nitrogen spray nozzle 3. In this way, by performing intermittent control of liquid nitrogen injection, drilling is performed as necessary while repeating the “melting step” for reliably forming the molten portion and the “removing step” for reliably removing the molten portion. Do. Further, after that, the laser head 1 and the liquid nitrogen injection nozzle 3 or the temperature sensor 4 of the monitoring means M are moved by moving means (not shown), so that continuous processing and cutting can be performed.

  As described above, in the present invention, the temperature sensor 4 (for example, thermography) is used to measure the portion where the target portion is melted by the laser, and the viscosity of the oxide is reduced as shown in the graph of FIG. When the temperature becomes higher than the temperature, liquid nitrogen is sprayed onto the melted portion, and the dross is blown away while cooling to prevent re-welding of the dross. In other words, in the present invention, after the laser irradiation, the temperature of the melted part is monitored, and liquid nitrogen is injected based on the fact that the surface tension of the melted part of the material exceeds that of the unmelted part. Can do.

  In this case, in order to obtain the effect of preventing dross re-welding by cooling while blowing the dross, it is desirable that the inert substance is liquid nitrogen. Even nitrogen gas can avoid safety problems due to bonding with hydrogen, but liquid nitrogen is desirable for cooling.

  In the second embodiment, as shown in FIGS. 5 and 6, the liquid nitrogen injection nozzle 3 of FIG. 3 is replaced with a dry ice blast injection nozzle 3A, and the liquid nitrogen tank 6 is replaced with a dry ice storage tank 6A. FIG. 5 shows an example in which dry ice is used as the inert material injection means K in the case of using a laser processing / cutting apparatus, and FIG. 6 in the case of using a plasma processing / cutting apparatus.

  The present invention uses inerts with the recognition that in the environment where fuel debris is placed, not only oxygen but also water is dangerous. Example 2 uses dry ice blasting instead of liquid nitrogen.

  Also in this case, in order to obtain the effect of cooling the surroundings while blowing the dross, it is desirable that the inert substance is dry ice blast. Even carbon dioxide gas can avoid safety problems due to bonding with hydrogen, but dry ice blasting is desirable for cooling.

  In the third embodiment, as shown in FIGS. 5 and 6, the monitoring unit M is the monitoring unit MA, and monitoring by a camera is performed instead of temperature measurement. The size of the melted part dross is monitored by a camera, and blow-off is executed when the predetermined size is reached. In this case, 4B is a camera and 7B is a camera controller.

  An example of the processing procedure by the control device 10 in this case is shown in FIG. According to the processing flow of FIG. 7, a series of processing processes are started in the first processing step S1. The treatment process includes a laser irradiation process. In the next processing step S7, image information in the vicinity of the fusion part is obtained through the camera 4B and the camera controller 7B of the monitoring means MA, and a shape measurement preparation process is performed. If the shape can be measured, in the next processing step S3, the laser irradiation means R is driven to process / cut the workpiece (cutting target portion) 8.

  The monitoring means MA continues to obtain image information in the vicinity of the melted part through the camera 4B and the camera controller 7B, and in processing step S8, it is determined whether the measured shape (size) is greater than or less than a threshold value. The shape and size when the shape measured in process step S8 (the dross retention) is in a state before the cutting is hindered are set as threshold values. Thus, if it is equal to or greater than the threshold value, it is determined that the blow-off timing has been reached, and the inert material jetting means K is driven in the processing step S5, and dross removal processing is performed by jetting liquid nitrogen.

  When the shape measured in the process step S8 is equal to or less than the threshold value, it is determined that the blow-off time has not been reached, and the process returns to the process step S7 to wait for the dross staying in the melted part by continuing the laser irradiation.

  The above heating and blow-off processing is continuously executed while shifting the work position as appropriate until the processing / cutting work of the work piece (cutting target part) 8 planned in advance is completed. It becomes.

  According to the present invention described above, the so-called “fuel debris”, in which the reactor fuel is melted due to the loss of the coolant in the Fukushima No. 1 nuclear power plant and is cooled and solidified together with the reactor structural material and the control rod, is targeted. It is suitable for. It is possible to ensure safety in a hydrogen generation environment by injecting an inert material without using a water jet. In addition, intermittent control is performed so that dross removal functions effectively.

1: Laser head 2: Lens 3: Liquid nitrogen injection nozzle 3A: Dry ice blast injection nozzle 4: Temperature sensor 4B: Camera 5: Laser oscillator 6: Liquid nitrogen tank 6A: Dry ice storage tank 7: Signal converter 7B: Camera Controller 8: Work piece (part to be cut)
10: Controller 11: Electrode 12: Plasma head K: Inert body injection means M, MA: Monitoring means M
P: Plasma arc generating means R: Laser irradiation means

Claims (10)

A thermal cutting device that applies thermal energy to a workpiece to cut and process the workpiece,
Thermal energy application means for applying thermal energy to the workpiece, inert body injection means for injecting and removing the inert material on the dross generated on the workpiece, and dross generated on the workpiece The monitoring means for monitoring the melted portion which is a region, the thermal energy applying means, and the inert substance injection means are controlled, and the inert substance injection by the inert substance injection means is performed using information from the monitoring means A thermal cutting apparatus comprising control means for determining timing and executing intermittent control. The thermal cutting device according to claim 1,
A thermal cutting apparatus comprising laser irradiation means for irradiating a laser beam focused on a workpiece as the thermal energy application means. The thermal cutting device according to claim 1,
A thermal cutting apparatus comprising plasma arc discharge means for discharging plasma arc as the thermal energy applying means. The thermal cutting device according to claim 1,
A thermal cutting device provided with a gas cutting means using oxidation heat of high pressure oxygen ejected from a gas cutting nozzle as the thermal energy applying means. The thermal cutting device according to any one of claims 1 to 4,
The thermal cutting apparatus, wherein the inert substance is liquid nitrogen. The thermal cutting device according to any one of claims 1 to 4,
A thermal cutting apparatus, wherein the inert material is dry ice. The thermal cutting device according to any one of claims 1 to 6,
The monitoring means monitors the temperature of the melted portion, which is a dross region generated on the workpiece, and the control means uses temperature information from the monitoring means to inactivate the inert material by the inert material injection means. A thermal cutting device that performs intermittent control by determining an injection timing. The thermal cutting device according to any one of claims 1 to 6,
The monitoring means monitors the shape of the melted portion, which is a dross region generated on the workpiece, and the control means uses the shape information from the monitoring means to detect the inactive material by the inactive material injection means. A thermal cutting device that performs intermittent control by determining an injection timing. The thermal cutting device according to any one of claims 1 to 6,
The monitoring means monitors the temperature of the molten part, which is a dross region generated on the workpiece, and the control means uses the temperature information from the monitoring means to determine that the surface tension of the molten part is the surface of the unmelted part. A thermal cutting device characterized by estimating that the tension has been exceeded, determining the injection timing of the inert body, and performing intermittent control.   This is a region of dross generated on the workpiece to be cut and processed by applying thermal energy to the workpiece, and to inject and remove the inert material on the dross generated on the workpiece by the heat energy. The thermal cutting method characterized by performing the intermittent control by determining the injection timing of the inert body using the information of the melting part.

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