JP2013018005A - Nitrogen supply device for laser beam machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nitrogen supply device for a laser beam machine capable of effectively utilizing nitrogen stored in a buffer tank, and reducing the size of a PSA device and that of the buffer tank.SOLUTION: The pressure of nitrogen generated by a PSA device 12 is boosted by a first booster machine 13 to store the nitrogen in a buffer tank 14, the nitrogen is supplied to a laser beam machine from a first nitrogen pipeline 15 when the pressure in the buffer tank is high, nitrogen increased in pressure by a second booster machine 19 of a second nitrogen pipeline 17 is supplied to the laser beam machine when the pressure in the buffer tank is low. The changeover of both the pipelines is performed by switchably opening/closing on-off valves 16, 18 respectively arranged on the respective pipelines with a pressure switch 22 for detecting the pressure in the buffer tank.

Description

  The present invention relates to a nitrogen supply device for a laser beam machine, and more particularly to a nitrogen supply device for a laser beam machine for supplying nitrogen generated by a nitrogen generator device to a laser beam machine at a preset relatively high pressure. .

  When performing processing such as cutting of stainless steel using a laser processing machine, an inert gas, such as nitrogen, is injected as an assist gas around the laser beam during laser processing, and the surface of the stainless steel, the cut surface and By setting the back surface to be a nitrogen atmosphere, reaction between oxygen in the atmosphere and stainless steel prevents burning and the like from occurring.

  When nitrogen is used as an assist gas, a nitrogen generator that concentrates nitrogen in the air, generally a high-purity nitrogen is produced using a PSA device, and if necessary, it remains in the nitrogen with a purifier. After removing a small amount of oxygen, pressurize the nitrogen to the pressure set in the laser processing machine with a booster, store the high-pressure nitrogen after boosting in the buffer tank, and supply nitrogen to the laser processing machine from the buffer tank (For example, refer nonpatent literature 1.).

Air Water Co., “PSA Nitrogen Generator for Laser Processing Machines”, [online], Air Water Co., Ltd. [Search June 29, 2011], Internet <URL: http: // www. awi.co.jp/bp/pg/laser.pdf>

  As described above, when nitrogen is supplied from the buffer tank to the laser processing machine, it is necessary to store nitrogen in the buffer tank at a pressure higher than the nitrogen pressure required by the laser processing machine. When the required nitrogen pressure is 3 MPa, it was necessary to store nitrogen in the buffer tank at a pressure of about 5 MPa. In this case, since the pressure in the buffer tank capable of supplying nitrogen from the buffer tank to the laser processing machine is 3 MPa or more, nitrogen cannot be supplied to the laser processing machine when the pressure in the buffer tank decreases to 3 MPa, Nitrogen in the buffer tank could not be used effectively.

  Therefore, when the fluctuation of the nitrogen usage amount of the laser processing machine is large, in order to correspond to the maximum nitrogen usage amount, a PSA device having a large amount of nitrogen generation compared to the average nitrogen usage amount of the laser processing machine or a large capacity or A plurality of buffer tanks are required, which is a cause of cost increase in the nitrogen supply device.

  If a buffer tank is not provided, a PSA device having a nitrogen generation capacity equal to or greater than the maximum nitrogen usage of the laser processing machine must be installed, resulting in a significant cost increase. Moreover, the built-in buffer tank of the PSA apparatus is mainly intended to make the purity of the generated nitrogen uniform and to reduce pressure fluctuations, and does not have a function of storing a large amount of high-pressure nitrogen.

  Accordingly, an object of the present invention is to provide a nitrogen supply device for a laser processing machine that can effectively use nitrogen stored in a buffer tank and can reduce the size of a PSA device or a buffer tank.

  In order to achieve the above object, a nitrogen supply device for a laser beam machine according to the present invention comprises a nitrogen generating means for generating nitrogen, a booster for increasing the nitrogen generated by the nitrogen generating means to a preset storage pressure, In a nitrogen supply device for a laser processing machine, comprising: a buffer tank for storing nitrogen boosted by the booster; and a nitrogen supply path for supplying nitrogen in the buffer tank to the laser processing machine. A second nitrogen supply path including a second booster having a large amount is provided in parallel with the nitrogen supply path, a first on-off valve is provided in the nitrogen supply path, and the second booster in the second nitrogen supply path is provided. A second on-off valve is provided on the suction side, and the pressure in the buffer tank is detected. When the detected pressure is equal to or higher than a preset switching pressure, the first on-off valve is opened to 2 Close the on-off valve, the detected pressure at the time of less than the switching pressure force is characterized in that a pressure switch for opening the second on-off valve closes the first on-off valve.

  Furthermore, the nitrogen supply device for a laser beam machine according to the present invention is provided from an external nitrogen supply source via a third on-off valve between the second booster and the second on-off valve in the second nitrogen supply path. An external nitrogen introduction path for introducing nitrogen into the second nitrogen supply path is provided, and the pressure switch opens the third on-off valve when the pressure in the buffer tank is lower than a preset lower limit pressure. The first on-off valve and the second on-off valve may be closed. Further, the nitrogen generating means is preferably a PSA device that generates nitrogen having a purity of 99.999% or more, and the second booster automatically operates when the suction side pressure reaches a preset operating pressure. It is preferable that the operation is started automatically and stopped automatically when the suction side pressure falls below the operation pressure.

  According to the nitrogen supply device for a laser processing machine of the present invention, when the pressure in the buffer tank is equal to or higher than the switching pressure, the first on-off valve is opened to supply nitrogen to the laser processing machine from the nitrogen supply path with the pressure in the buffer tank. When the pressure in the buffer tank is less than the switching pressure, the second on-off valve is opened and nitrogen boosted by the second booster is supplied to the laser processing machine from the second nitrogen supply path, so the pressure in the buffer tank is reduced. However, nitrogen can be supplied to the laser processing machine. As a result, the nitrogen generated by the nitrogen generating means can be used without waste, and the amount of nitrogen that can be supplied to the laser processing machine increases. Equipment such as the generating means, the booster, and the buffer tank can be downsized. In addition, when equipment having the same ability is used, there is a margin in operation, so it is possible to reduce power consumption.

  Furthermore, by providing an external nitrogen introduction path, when the amount of nitrogen used by the laser processing machine increases rapidly, nitrogen from a nitrogen cylinder or a liquefied nitrogen storage tank provided outside the apparatus is increased by a second pressure. The pressure can be increased by a machine and supplied to a laser processing machine. Further, by using a PSA apparatus that generates nitrogen having a purity of 99.999% or more as the nitrogen generating means, it is not necessary to provide a purifying apparatus for removing oxygen remaining in the nitrogen, thereby reducing the apparatus cost. be able to. Furthermore, by using a booster that automatically operates and stops in response to fluctuations in the suction side pressure as the second booster, it is only necessary to open and close each on-off valve by a pressure switch without providing a separate control means. The nitrogen supply path can be automatically changed.

It is explanatory drawing which shows one example of the nitrogen supply apparatus for laser processing machines of this invention.

  The nitrogen supply device for a laser beam machine shown in the present embodiment includes a PSA device (pressure fluctuation adsorption type nitrogen generator) 12 which is a nitrogen generating means for generating nitrogen using the air compressed by the raw material air compressor 11 as a raw material, A booster (first booster) 13 for boosting nitrogen generated in the PSA device 12 to a preset storage pressure, a buffer tank 14 for storing nitrogen boosted by the first booster 13, and the buffer tank 14 A nitrogen supply path (first nitrogen supply path) 15 for supplying nitrogen in the laser processing machine (not shown), a first on-off valve 16 provided in the first nitrogen supply path 15, and the first nitrogen A second nitrogen supply path 17 branched from the upstream side of the first on-off valve 16 of the supply path 15 and provided in parallel to the first nitrogen supply path 15, and provided in the second nitrogen supply path 17 Second on-off valve 1 And a second booster 19 provided on the downstream side of the second on-off valve 18.

  Further, the laser processing machine nitrogen supply apparatus shown in the present embodiment includes an external nitrogen introduction path 20 connected between the second on-off valve 18 and the second booster 19 in the second nitrogen supply path 17, and the external And a third on-off valve 21 provided in the nitrogen introduction path 20. In addition, a pressure switch (PS) 22 is provided to open and close the first on-off valve 16, the second on-off valve 18, and the third on-off valve 21 according to the pressure in the buffer tank 14, and laser processing is provided. A nitrogen supply pipe 23 that connects the machine nitrogen supply device and the laser processing machine is provided with a pressure reducing valve 24 for adjusting the supply pressure to the laser processing machine to a preset pressure.

  The pressure switch 22 detects the pressure in the buffer tank 14 and opens the first on-off valve 16 and closes the second on-off valve 18 and the third on-off valve 21 when the detected pressure is equal to or higher than a preset switching pressure. When the detected pressure is less than the switching pressure and not less than a preset lower limit pressure, the second on-off valve 18 is opened, the first on-off valve 16 and the third on-off valve 21 are closed, and the detected pressure is When the pressure is less than the lower limit pressure, the third on-off valve 21 is opened and the first on-off valve 16 and the second on-off valve 18 are closed.

  As the PSA device 12, a well-known PSA device that concentrates nitrogen in the air by changing the pressure of the adsorption cylinder filled with the adsorbent can be used. Preferably, the type and operating conditions of the adsorbent are appropriately selected. Thus, a PSA apparatus capable of generating nitrogen having a purity of 99.999% or more is used. When the amount of oxygen remaining in the nitrogen generated in the PSA device 12 is large, it is possible to remove the oxygen and increase the nitrogen purity by adding a purification device as necessary.

  The PSA device 12 and the first booster 13 are used in accordance with the amount of nitrogen required by the laser processing machine, and usually have the ability to cover the average usage during the operating time of the laser processing machine. Is selected. The buffer tank 14 has a capacity corresponding to the fluctuation state of the amount of nitrogen used in the laser processing machine. Normally, the upper limit pressure is set to 5 MPa or less, and when a large amount of nitrogen needs to be stored, a plurality of buffer tanks 14 are used. Buffer tanks can be installed.

  The second booster 19 has a discharge amount corresponding to the maximum amount of nitrogen used in the laser processing machine, and normally, with respect to the discharge amount of the first booster 13 corresponding to the average use amount of nitrogen. A booster having a discharge amount about twice as high is used as the second booster 19. Moreover, the discharge pressure of the 1st pressure | voltage riser 13 should just have the capability more than the upper limit pressure of the buffer tank 14, and the discharge pressure of the 2nd pressure | voltage riser 19 should be more than the supply pressure to a laser processing machine. Further, the second booster 19 automatically starts operation when the suction side pressure reaches a preset operation pressure, and automatically stops when the suction side pressure falls below the operation pressure. It is preferable to use a booster that is in an idling state.

  As each on-off valve 16, 18, 21, a known electric valve or pneumatic valve that can be opened / closed by a signal from the pressure switch 22 can be used. Also, an appropriate nitrogen supply source such as a cylinder filled with high-pressure nitrogen gas or a liquefied nitrogen storage tank can be connected to the external nitrogen introduction path 20.

  An operation state in which nitrogen is supplied to the laser beam machine using the thus formed nitrogen supply device for the laser beam machine will be described below. Here, the nitrogen supply pressure to the laser processing machine is 3 MPa, the upper limit pressure of the buffer tank 14 is 5 MPa, the switching pressure set in the pressure switch 22 is 3.5 MPa, and the lower limit pressure is 1 MPa.

  First, as a preparation stage, the operation of the PSA device 12 and the first booster 13 is started, and the buffer tank 14 is filled with the pressurized nitrogen. When the pressure in the buffer tank 14 reaches an upper limit pressure, for example, 5 MPa, the first booster 13 enters an idling state, and the suction side pressure of the first booster 13, that is, the outlet side pressure of the PSA device 12 increases, thereby causing PSA. The raw material air compressor 11 of the apparatus 12 is also in an idling state and is in a standby state. In this standby state, since the detected pressure of the pressure switch 22 is equal to or higher than the switching pressure, the first on-off valve 16 is in the open state, and the second on-off valve 18 and the third on-off valve 21 are both in the closed state. .

  When the laser processing machine is operated and the use of nitrogen is started, high-pressure nitrogen stored in the buffer tank 14 passes through the first open / close valve 16 and the first nitrogen supply path 15, and then the pressure reduction valve 24 of the pipe 23. The pressure is adjusted to 3 MPa and supplied to the laser processing machine. When the pressure in the buffer tank 14 decreases with the supply of nitrogen to the laser processing machine, the first booster 13 and the raw material air compressor 11 are changed from the idling state to the operating state, and the nitrogen generated from the PSA device 12 When the purity of the gas reaches a specified value or higher, nitrogen boosted by the first booster 13 is introduced into the buffer tank 14. When the amount of nitrogen used by the laser processing machine is relatively small, high-pressure nitrogen generated in the PSA device 12, boosted by the first booster 13, and introduced into the buffer tank 14 passes through the first nitrogen supply path 15. Then, the operation state supplied to the laser processing machine and the standby state described above are repeated.

  When the amount of nitrogen used in the laser processing machine increases and the pressure of nitrogen stored in the buffer tank 14 drops below the switching pressure of less than 3.5 MPa, the pressure switch 22 that detects the pressure drop is actuated to activate the first pressure switch 22. The first on-off valve 16 changes from the open state to the closed state, the second on-off valve 18 changes from the closed state to the open state, and the nitrogen in the buffer tank 14 passes through the second nitrogen supply path 17 by the second booster 19 to 3 MPa or more. Then, the pressure is adjusted to 3 MPa by the pressure reducing valve 24 of the pipe 23 and then supplied to the laser processing machine.

  When the state of supplying nitrogen from the second nitrogen supply path 17 continues for a long time and the pressure in the buffer tank 14 decreases to less than 1 MPa, which is the lower limit pressure, the second on-off valve 18 is closed by the pressure switch 22. 3 The on-off valve 21 is switched to the open state, and nitrogen from a nitrogen supply source provided outside the apparatus is introduced into the suction side of the second booster 19 through the external nitrogen introduction path 20, and the second booster 19 After the pressure is increased, the laser beam is supplied to the laser processing machine.

  Since nitrogen in the buffer tank 14 is not consumed while nitrogen is introduced from the external nitrogen introduction path 20, nitrogen generated in the PSA device 12 is boosted by the first booster 13 and introduced into the buffer tank 14. As a result, the pressure in the buffer tank 14 gradually increases. When the pressure in the buffer tank 14 becomes equal to or higher than the lower limit pressure, the third on-off valve 21 is closed and the second on-off valve 18 is opened, and the nitrogen in the buffer tank 14 is supplied to the second nitrogen supply path 17 and the second pressure increase. The machine 19 is supplied to the laser processing machine through the machine 19.

  When the amount of nitrogen used in the laser processing machine decreases and the amount of nitrogen introduced into the buffer tank 14 from the PSA device 12 via the first booster 13 exceeds the amount of nitrogen supplied to the laser processing machine, the pressure in the buffer tank 14 Gradually rises above the switching pressure, the pressure switch 22 switches the first on-off valve 16 to the open state and the second on-off valve 18 to the closed state. Through this, nitrogen is supplied to the laser processing machine. Further, when the second on-off valve 18 is closed, the second booster 19 stops operating or enters an idling state.

  In this way, when the pressure in the buffer tank 14 decreases and it becomes difficult to supply nitrogen from the first nitrogen supply path 15, the nitrogen supply is switched from the first nitrogen supply path 15 to the second nitrogen supply path 17. By supplying nitrogen boosted by the second booster 19 to the laser processing machine, nitrogen in the buffer tank 14 can be used effectively. As a result, the nitrogen generated in the PSA device 12 can be used without waste, and the amount of nitrogen that can be supplied to the laser processing machine increases. Nitrogen can be supplied.

  Furthermore, by providing the external nitrogen introduction path 20, nitrogen can be introduced from a nitrogen supply source provided outside the apparatus, and can be boosted by the second booster 19 and supplied to the laser processing machine. It is also possible to cope with a case where the amount of nitrogen used in the laser processing machine increases rapidly. Further, by using the PSA device 12 that generates nitrogen having a purity of 99.999% or more, it is not necessary to provide a purification device for removing oxygen remaining in the nitrogen, thereby reducing the device cost and running cost. Can do. Further, by using a booster that automatically operates and stops in response to fluctuations in the suction side pressure as the second booster 19, each on-off valve 16 by the pressure switch 22, The second booster 19 can be automatically operated and stopped only by opening and closing the valves 18 and 21.

  Note that the external nitrogen introduction path may be provided as necessary, and when there is a large amount of oxygen remaining in nitrogen generated by a nitrogen generating means such as a PSA apparatus, a purification apparatus for removing oxygen can be provided. Further, it is possible to provide a control means for centrally controlling and monitoring the nitrogen generating means, each booster, and each on-off valve based on the pressure in the buffer tank and the amount of nitrogen supplied to the laser processing machine.

  DESCRIPTION OF SYMBOLS 11 ... Raw material air compressor, 12 ... PSA apparatus, 13 ... 1st pressure | voltage riser, 14 ... Buffer tank, 15 ... 1st nitrogen supply path, 16 ... 1st on-off valve, 17 ... 2nd nitrogen supply path, 18 ... 1st 2 on-off valve, 19 ... second booster, 20 ... external nitrogen introduction path, 21 ... third on-off valve, 22 ... pressure switch, 23 ... nitrogen supply pipe, 24 ... pressure reducing valve

Claims (4)

  Nitrogen generating means for generating nitrogen, a booster for boosting nitrogen generated by the nitrogen generating means to a preset storage pressure, a buffer tank for storing nitrogen boosted by the booster, and in the buffer tank In a nitrogen supply apparatus for a laser processing machine comprising a nitrogen supply path for supplying nitrogen to a laser processing machine, the second nitrogen supply path provided with a second booster having a larger discharge amount than the booster is used as the nitrogen supply path. And a second on-off valve on the suction side of the second booster in the second nitrogen supply path, and a pressure in the buffer tank. When the detected pressure is equal to or higher than a preset switching pressure, the first on-off valve is opened and the second on-off valve is closed. When the detected pressure is less than the switching pressure, the first on-off valve is closed. Laser processing machine for the nitrogen supply device according to claim 1 Close off valve to the provision of the pressure switch for opening the second on-off valve.   External nitrogen introduction for introducing nitrogen from an external nitrogen supply source into the second nitrogen supply path via a third on-off valve between the second booster and the second on-off valve in the second nitrogen supply path A path is provided, and the pressure switch opens the third on-off valve and closes the first on-off valve and the second on-off valve when the pressure in the buffer tank is lower than a preset lower limit pressure. The nitrogen supply device for a laser beam machine according to claim 1.   The nitrogen supply device for a laser beam machine according to claim 1 or 2, wherein the nitrogen generation means is a PSA device that generates nitrogen having a purity of 99.999% or more.   The second booster starts automatically when the suction side pressure reaches a preset operating pressure, and automatically stops when the suction side pressure falls below the operating pressure. The nitrogen supply device for a laser beam machine according to any one of claims 1 to 3.

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