Gas cutting apparatus and gas cutting method

Abstract

To provide a gas cutting device that can automatically adjust to the appropriate preheating time for each cut. [Solution] The gas cutting device 1 is a gas cutting device for cutting off an unnecessary portion W2 of a workpiece W, and comprises a torch 11, a temperature sensor 12, and a controller 3. The torch 11 is capable of spraying a preheating flame A1 and cutting oxygen A2. The temperature sensor 12 detects the temperature of the cutting start point P1 of the workpiece W. The controller 3 starts cutting when the temperature rises when cutting oxygen A2 is sprayed from the torch 11 while the preheating flame A1 is being sprayed from the torch 11.

Description

Technical Field

[0006] ,

[0001] The present invention relates to a gas cutting device and a gas cutting method.

Background Art

[0002] For cutting thick steel plates and the like, gas cutting by an orthogonal robot or an automatic machine is frequently used. In the case of thick steel plates, there are edges (corners) where cutting is easy to start, and since their shape is simple and highly accurate, it was easy to set the preheating time before moving the torch for cutting.

[0003] Also, a gas cutting device is disclosed that measures the temperature of the cutting start site and automatically ends preheating and starts moving the torch when a predetermined threshold value is exceeded (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the other hand, in the case of cast steel parts, due to variations specific to casting in dimensions and casting skin, manual gas cutting is generally widely used for removing risers such as risering and runners of cast steel parts, and automation that can handle risers of various positions and shapes is strongly desired.

[0006] Due to variations in dimensions and casting surface, as well as positional shifts at the temperature measurement location, the temperature data at the cutting start point becomes unstable even for parts of the same shape. Furthermore, the delay in the oxidation reaction caused by the high-melting-point film on the cast surface also has an effect. For this reason, it has been difficult to adjust to an appropriate preheating time by setting a predetermined threshold for the temperature of the cutting start point, as described in Patent Document 1 above. If the preheating time is too long, overheating occurs and gouging takes place, and if the preheating time is too short, the preheating temperature necessary to start the oxidation reaction cannot be obtained, making it impossible to start cutting.

[0007] The purpose of this disclosure is to provide a gas cutting device and a gas cutting method that can automatically adjust to an appropriate preheating time for each cut. [Means for solving the problem]

[0008] A gas cutting device according to one aspect of the present disclosure is a gas cutting device for cutting a predetermined part of an object, and comprises a torch, a temperature sensor, and a controller. The torch is capable of spraying a preheating flame and cutting oxygen. The temperature sensor detects the temperature of the cutting start site of the object. The controller starts cutting when the temperature rises when cutting oxygen is sprayed from the torch while the preheating flame is being sprayed from the torch.

[0009] Another gas cutting method according to another aspect of the present disclosure is a gas cutting method for cutting a predetermined part of an object. This gas cutting method comprises: injecting a preheating flame from a torch; injecting cutting oxygen from the torch while the preheating flame is being injected from the torch; detecting the temperature of the cutting start site of the object; and initiating cutting when the temperature rises after the cutting oxygen is injected from the torch. [Effects of the Invention]

[0010] According to aspects of this disclosure, it is possible to provide a gas cutting apparatus and a gas cutting method that can automatically adjust to an appropriate preheating time for each cut. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows the configuration of a gas cutting device according to an embodiment of the present disclosure. [Figure 2] Figure 1 is a block diagram showing the configuration of a gas cutting device. [Figure 3] Figure 1 is a front view showing the robot. [Figure 4] (a) An enlarged view of section C in Figure 3. (b) A schematic cross-sectional view showing the configuration of the torch in Figure 2(a). [Figure 5] This is a schematic diagram showing an example of a workpiece to be cut. [Figure 6] This is a diagram illustrating the procedure for cutting a workpiece. [Figure 7] This figure shows a graph illustrating the control of a gas cutting device according to the embodiments of this disclosure. [Figure 8] This is a flowchart illustrating the control method of the gas cutting device according to the embodiment of this disclosure. [Figure 9] This figure illustrates how to change the orientation of the torch in a modified gas cutting device according to this embodiment. [Figure 10] (a) A diagram illustrating the adjustment of the torch position in a modified gas cutting device of this embodiment; (b) A graph showing the time change of the cutting start location during preheating. [Modes for carrying out the invention]

[0012] The gas cutting apparatus described herein will be explained below with reference to the drawings.

[0013] Figure 1 is a diagram showing the configuration of the gas cutting device 1 of this embodiment. Figure 2 is a block diagram showing the configuration of the gas cutting device 1 of this embodiment. As shown in Figures 1 and 2, the gas cutting device 1 comprises a robot 2, a controller 3, a combustible gas cylinder 4, an oxygen cylinder 5, and a gas control panel 6.

[0014] As shown in FIG. 2, the robot 2 has a torch 11 described later and performs gas cutting of the workpiece W. The workpiece W is, for example, a cast part. The unnecessary portion of the workpiece W is cut by the gas cutting device 1. Note that the workpiece W is not limited to cast parts and may be a steel plate or the like.

[0015] The controller 3 transmits a control signal to the robot main body 13 to control the robot 2. The combustible gas cylinder 4 stores combustible gas for supplying to the torch 11. The oxygen cylinder 5 stores oxygen for supplying to the torch 11. The gas control panel 6 controls the supply of combustible gas from the combustible gas cylinder 4 to the torch 11. The gas control panel 6 controls the supply of oxygen from the oxygen cylinder 5 to the torch 11. The controller 3 transmits a control signal to the gas control panel 6 to control the gas control panel 6.

[0016] FIG. 3 is a front view showing the appearance of the robot 2. As shown in FIG. 3, the robot 2 has a torch 11, a temperature sensor 12, and a robot main body 13 (torch moving part). The torch 11 and the temperature sensor 12 are attached to the robot main body 13. The robot main body 13 is, for example, a vertically articulated robot. The robot main body 13 has, for example, a fixed part 20, a first movable part 21, a second movable part 22, a third movable part 23, a fourth movable part 24, a fifth movable part 25, and a sixth movable part 26.

[0017] The fixing part 20 is fixed to a table 7 provided in a gas cutting robot booth B where gas cutting is performed. The first movable part 21 is attached to the fixing part 20 so as to be rotatable about a shaft 13a along the vertical direction. The second movable part 22 is attached to the first movable part 21 so as to be rotatable about a shaft 13b along the horizontal direction. The third movable part 23 is attached to the tip of the second movable part 22 so as to be rotatable about a shaft 13c. The shaft 13c is arranged parallel to the shaft 13b. The fourth movable part 24 is attached to the third movable part 23 so as to be rotatable about a shaft 13d. The shaft 13d is arranged perpendicular to the shaft 13c. The fifth movable part 25 is attached to the fourth movable part 24 so as to be rotatable about a shaft 13e as a stop. The shaft 13e is arranged perpendicular to the shaft 13d. The sixth movable part 26 is attached to the fifth movable part 25 so as to be rotatable about a shaft 13f. The shaft 13f is arranged perpendicular to the shaft 13e.

[0018] In the robot body 13, motors (not shown) for driving the first movable part 21, the second movable part 22, the third movable part 23, the fourth movable part 24, the fifth movable part 25, and the sixth movable part 26 are arranged with respect to their respective shafts. These motors are driven based on drive signals transmitted from the controller 3, and the robot body 13 operates. Examples of the motor include a servo motor.

[0019] Fig. 4(a) is an enlarged view of part C in Fig. 2. As shown in Fig. 4(a), a torch 11 and a temperature sensor 12 are attached to the sixth movable part 26 of the robot body 13.

[0020] The torch 11 can inject a preheating flame and cutting oxygen. As shown in Fig. 4(a), the torch 11 is attached to the sixth movable part 26 of the robot body 13 via a bracket 14.

[0021] Figure 4(b) is a schematic cross-sectional view illustrating the torch 11. As shown in Figure 4(b), the torch 11 has a preheating flame nozzle 11a and a cutting oxygen nozzle 11b. A preheating flame A1 is ejected from the preheating flame nozzle 11a. The preheating flame nozzle 11a is an annular opening at the tip 11e of the torch 11. The preheating flame A1 is a mixture of combustible gas and oxygen. The preheating flame A1 is a neutral flame. The cutting start area of ​​the workpiece W is locally heated by the preheating flame A1 to a temperature range where oxidation reactions occur (for example, about 900°C).

[0022] Cutting oxygen A2 is injected from the cutting oxygen nozzle 11b. The cutting oxygen nozzle 11b is located in the center of the tip 11e. The cutting oxygen nozzle 11b is located inside the preheating flame nozzle 11a at the tip 11e. The cutting oxygen nozzle 11b is surrounded by the preheating flame nozzle 11a. By injecting high-pressure cutting oxygen into the cutting start area of ​​the workpiece W, which has been preheated to a temperature range where oxidation reactions occur with the preheating flame A1, the oxidation reaction proceeds, generating heat and enabling cutting.

[0023] Figures 5(a) and 5(b) are schematic diagrams showing examples of workpieces W to be cut. The workpieces W shown in Figures 5(a) and 5(b) have a product portion W1 and a waste portion W2. In the workpiece W shown in Figure 5(a), the product portion W1 is plate-shaped and the waste portion W2 is rectangular. In the workpiece W shown in Figure 5(b), the product portion W1 is plate-shaped and the waste portion W2 is cylindrical.

[0024] As shown in Figures 5(a) and 5(b), the product portion W1 and the unwanted portion W2 are cut, and the unwanted portion W2 is removed from the workpiece W. As shown in Figures 5(a) and 5(b), the end of the unwanted portion W2 is preheated as the cutting start point P1, and after preheating is complete, the torch 11 is moved along the cutting direction D to perform the cutting. In Figure 4(a), the cutting line M along which the workpiece W is cut is shown as a dotted line.

[0025] As shown in Figure 5(a), when the unwanted portion W2 is rectangular, the cutting start point P1 is a corner, making localized heating easier and allowing the temperature to rise quickly during preheating. On the other hand, as shown in Figure 5(b), when the unwanted portion W2 is cylindrical, localized heating is difficult, making it difficult for the temperature to rise quickly during preheating.

[0026] The temperature sensor 12 measures the temperature of the cutting start point P1. The temperature sensor 12 measures the temperature of the area to be cut by the torch 11. The temperature sensor 12 is, for example, an infrared thermometer. The temperature sensor 12 transmits the measured temperature information to the controller 3 as a temperature information signal. The temperature sensor 12 is mounted on a bracket 14 between the sixth movable part 26 of the robot body 13 and the torch 11. As shown in Figure 4(a), the temperature sensor 12 is mounted on the bracket 14 at an angle to the torch 11 in order to measure the temperature of the area to be preheated by the torch 11. After preheating, the temperature sensor 12 moves along the cutting direction C with the torch 11 and measures the temperature of the cutting area.

[0027] As shown in Figure 2, the gas cutting device 1 further includes a piping 31 for combustible gas, a piping 32 for preheating oxygen, and a piping 33 for cutting oxygen. The piping 31 for combustible gas connects the combustible gas cylinder 4 to the preheating flame nozzle 11a of the torch 11. The piping 32 for preheating oxygen connects the oxygen cylinder 5 to the preheating flame nozzle 11a of the torch 11. The piping 33 for cutting oxygen connects the oxygen cylinder 5 to the cutting oxygen nozzle 11b of the torch 11.

[0028] The gas control panel 6 includes a solenoid valve 41 for combustible gas, a mass flow controller 42 for combustible gas, a solenoid valve 43 for preheating oxygen, a mass flow controller 44 for preheating oxygen, a solenoid valve 45 for cutting oxygen, and a mass flow controller 46 for cutting oxygen.

[0029] The combustible gas solenoid valve 41 and the combustible gas mass flow controller 42 are located in the combustible gas piping 31. The combustible gas solenoid valve 41 opens and closes the combustible gas piping 31 in response to an open / close instruction signal from the controller 3. The combustible gas mass flow controller 42 controls the flow rate of combustible gas flowing through the combustible gas piping 31. The combustible gas mass flow controller 42 controls the flow rate of combustible gas based on the flow rate instruction signal from the controller 3. When the combustible gas solenoid valve 41 is open, the flow rate controlled by the combustible gas mass flow controller 42 is supplied from the combustible gas cylinder 4 to the preheating flame nozzle 11a of the torch 11. The combustible gas mass flow controller 42 has a flow sensor, a flow control valve, and an electrical circuit, and controls the flow rate of combustible gas by adjusting the flow control valve so that the flow rate from the flow sensor matches the flow rate instruction signal from the controller 3. The structure of the mass flow controller 44 for preheating oxygen is the same as that of the mass flow controller 42 for combustible gas.

[0030] The preheating oxygen solenoid valve 43 and the preheating oxygen mass flow controller 44 are located in the preheating oxygen piping 32. The preheating oxygen solenoid valve 43 opens and closes the preheating oxygen piping 32 in response to an opening / closing instruction signal from the controller 3. The preheating oxygen mass flow controller 44 controls the flow rate of oxygen flowing through the preheating oxygen piping 32. When the preheating oxygen solenoid valve 43 is open, the flow rate controlled by the preheating oxygen mass flow controller 44 is supplied from the oxygen cylinder 5 to the preheating flame nozzle 11a of the torch 11.

[0031] The combustible gas mass flow controller 42 and the preheated oxygen mass flow controller 44 adjust the flow rates of the combustible gas and oxygen, respectively, to inject a neutral preheated flame from the preheated flame nozzle 11a. The combustible gas mass flow controller 42 and the preheated oxygen mass flow controller 44 transmit the measured flow rate information as a flow rate information signal to the controller 3.

[0032] The cutting oxygen solenoid valve 45 and the cutting oxygen mass flow controller 46 are located in the cutting oxygen piping 33. The cutting oxygen solenoid valve 45 opens and closes the cutting oxygen piping 33. The cutting oxygen solenoid valve 45 opens and closes the cutting oxygen piping 33 in response to an open / close instruction signal from the controller 3. The cutting oxygen mass flow controller 46 controls the flow rate of oxygen flowing through the cutting oxygen piping 33. When the cutting oxygen solenoid valve 45 is open, the flow rate controlled by the cutting oxygen mass flow controller 46 is supplied from the oxygen cylinder 5 to the cutting oxygen nozzle 11b of the torch 11. The cutting oxygen mass flow controller 46 transmits the measured flow rate information to the controller 3 as a flow rate information signal.

[0033] Controller 3 controls the robot 2 and the gas control panel 6. Controller 3 includes memory such as RAM and ROM, and a processor such as a CPU. Controller 3 may also include auxiliary storage devices such as an SSD or HDD. Controller 3 stores programs and data for controlling the robot 2 and the gas control panel 6.

[0034] Controller 3 receives temperature information signals transmitted from temperature sensor 12. Controller 3 receives flow rate information signals from combustible gas mass flow controller 42, preheating oxygen mass flow controller 44, and cutting oxygen mass flow controller 46. Controller 3 controls the opening and closing of combustible gas solenoid valve 41, preheating oxygen solenoid valve 43, and cutting oxygen solenoid valve 45 by transmitting open / close instruction signals to combustible gas solenoid valve 41, preheating oxygen solenoid valve 43, and cutting oxygen solenoid valve 45. Controller 3 controls combustible gas mass flow controller 42 and preheating oxygen mass flow controller 44 by transmitting flow rate instruction signals to combustible gas mass flow controller 42 and preheating oxygen mass flow controller 44. Controller 3 drives the robot body 13 by transmitting drive signals to multiple motors of the robot body 13. Controller 3 adjusts the positions of the torch 11 and temperature sensor 12 by driving the robot body 13.

[0035] Figures 6(a) and 6(b) are schematic diagrams illustrating the procedure for cutting workpiece W. In Figures 6(a) and 6(b), only the unnecessary portion W2 of workpiece W is shown. As shown in Figure 6(a), when cutting workpiece W, the cutting start point P1 of workpiece W is preheated by injecting a preheating flame A1 from the preheating flame nozzle 11a of the torch 11. Then, as shown in Figure 6(b), when the temperature of the cutting start point P1 reaches the temperature at which the oxidation reaction proceeds, cutting oxygen A2 is injected from the cutting oxygen nozzle 11b of the torch 11, causing the oxidation reaction to proceed and generating oxidation heat. This oxidation heat melts the cutting area, and the slag is blown away by the injection of cutting oxygen A2. In this state with cutting oxygen A2 being injected, by moving the torch 11 in the cutting direction D, the inside of the cutting groove is continuously melted, and the cutting of workpiece W proceeds. On the other hand, when cutting oxygen A2 is injected from the cutting oxygen nozzle 11b of the torch 11, if the temperature of the cutting start site P1 of the torch 11 has not risen to the temperature at which the oxidation reaction proceeds, the injection of cutting oxygen A2 will lower the temperature of the cutting start site P1. In the gas cutting device 1 of this embodiment, the controller 3 determines whether or not to start cutting based on this temperature change of the cutting start site P1.

[0036] Figure 7 is a graph illustrating the control by the controller 3 of the gas cutting device in this embodiment. In the graphs shown in Figure 7, the horizontal axis represents time, and the vertical axis represents the temperature of the cutting site or the gas flow rate. Graph G1 (dotted line) shows the temperature of the cutting site. The temperature of the cutting site is a value measured by the temperature sensor 12. Graph G2 (dash-dotted line) shows the flow rate of hydrogen gas as an example of a combustible gas. The flow rate of the combustible gas is a value measured by the combustible gas mass flow controller 42. Graph G3 (double-dash-dotted line) shows the flow rate of preheating oxygen. The flow rate of preheating oxygen is a value measured by the preheating oxygen mass flow controller 44. Graph G4 (solid line) shows the flow rate of cutting oxygen. The flow rate of cutting oxygen is a value measured by the cutting oxygen mass flow controller 46.

[0037] The controller 3 controls the gas control panel 6 and the robot 2 to inject a preheating flame A1 from the torch 11 toward the cutting start point P1 of the workpiece W (time t1 in Figure 7). This starts the preheating of the cutting start point P1 of the workpiece W. Then, when the controller 3 detects from the temperature information signal from the temperature sensor 12 that the temperature of the cutting start point P1 has risen to a predetermined threshold temperature T1, it controls the gas control panel 6 to inject cutting oxygen A2 from the torch 11 toward the cutting start point P1 of the workpiece W (time t2). The predetermined threshold temperature T1 is set lower than the temperature at which the oxidation reaction proceeds (the temperature at which cutting can begin).

[0038] When cutting oxygen A2 is injected, the controller 3 determines, based on the temperature information signal from the temperature sensor 12, whether the temperature of the cutting start point P1 of the workpiece W has risen or fallen. For example, in Figure 7, the temperature of the cutting start point P1 has fallen due to the injection of cutting oxygen A2 at time t2. Therefore, the controller 3 determines that the temperature of the cutting start point P1 has not reached the temperature at which the oxidation reaction will proceed and has been cooled by the cutting oxygen A2, and controls the gas control panel 6 to stop the injection of cutting oxygen A2. When the cutting oxygen A2 is stopped, the temperature of the cutting start point P1 rises again due to the preheating flame A1.

[0039] Based on the temperature information signal from the temperature sensor 12, when the controller 3 detects that the temperature of the cutting start site P1 has risen by a predetermined temperature ΔT from the threshold temperature T1, it controls the gas control panel 6 to inject cutting oxygen A2 from the torch 11 (time t3). For example, in Figure 7, since the temperature of the cutting start site P1 is decreasing due to the injection of cutting oxygen A2 at time t3, the controller 3 controls the gas control panel 6 to stop the injection of cutting oxygen A2. Then, when the controller 3 detects that the temperature of the cutting start site P1 has risen by a predetermined temperature ΔT above the temperature at time t3, it controls the gas control panel 6 to inject cutting oxygen A2 from the torch 11 (time t4). In Figure 6, since the temperature of the cutting site is decreasing due to the injection of cutting oxygen A2 at time t4, the controller 3 controls the gas control panel 6 to stop the injection of cutting oxygen A2.

[0040] Thus, when the temperature of the cutting start site P1 decreases due to the injection of cutting oxygen A2, the controller 3 stops the injection of cutting oxygen A2 and waits until the temperature rises to a predetermined temperature ΔT, and repeats this process.

[0041] At time t4, when the controller 3 detects that the temperature of the cutting start site P1 has risen by a predetermined temperature ΔT above the temperature at time t4, it controls the gas control panel 6 to inject cutting oxygen A2 from the torch 11 (time t5). At time t5, the temperature of the cutting site has risen after the injection of cutting oxygen A2. At this point, the controller 3 determines that the temperature of the cutting site has reached the temperature at which the oxidation reaction can proceed and starts cutting. Time t5 can be considered the timing when cutting can be started. Starting cutting means moving the torch 11 from the cutting start site P1 toward a predetermined cutting direction D.

[0042] As described above, the controller 3 increases the temperature and determines whether the oxidation reaction is progressing by observing whether the temperature of the cutting start site P1 rises or falls due to the injection of cutting oxygen A2. If the temperature rises, the controller 3 starts cutting.

[0043] Next, the control method for the gas cutting device of this embodiment will be described. Figure 8 is a flowchart illustrating the control method for the gas cutting device of this embodiment.

[0044] First, in step S1, the controller 3 drives the robot body 13 by transmitting a drive command signal to position the torch 11 so that it faces a predetermined cutting start point P1 of the workpiece W.

[0045] Next, in step S2, the controller 3 injects a preheating flame A1 from the preheating flame nozzle 11a of the torch 11 toward the cutting start point P1. The controller 3 opens the combustible gas solenoid valve 41 by transmitting an open command signal and controls the combustible gas mass flow controller 42 by transmitting a flow command signal to allow combustible gas to flow from the combustible gas cylinder 4 to the combustible gas piping 31. Then, the controller 3 ignites the combustible gas with an igniter and burns it. The controller 3 also opens the preheating oxygen solenoid valve 43 by transmitting an open command signal and controls the preheating oxygen mass flow controller 44 by transmitting a flow command signal to allow oxygen to flow from the oxygen cylinder 5 to the preheating oxygen piping 32. This allows the preheating flame A1 to be injected from the preheating flame nozzle 11a of the torch 11.

[0046] Next, in step S3, the controller 3 detects that the cutting start site P1 has reached a predetermined threshold temperature T1 based on the temperature information signal from the temperature sensor 12.

[0047] In step S3, when it is detected that the cutting start point P1 has reached a predetermined threshold temperature T1, the control proceeds to step S4. In step S4, the controller 3 injects cutting oxygen A2 from the cutting oxygen nozzle 11b of the torch 11 toward the cutting start point P1. The controller 3 opens the cutting oxygen solenoid valve 45 by transmitting an open command signal. This allows cutting oxygen A2 to be injected from the cutting oxygen nozzle 11b of the torch 11.

[0048] Next, in step S5, the controller 3 determines whether the temperature of the cutting start site P1 has risen based on the temperature information signal from the temperature sensor 12. If it is determined in step S5 that the temperature of the cutting start site P1 has not risen, the control proceeds to step S6.

[0049] In step S6, the controller 3 controls the gas control panel 6 to stop the injection of cutting oxygen A2 from the torch 11. The controller 3 closes the cutting oxygen solenoid valve 45 by transmitting a close command signal.

[0050] Next, in step S7, the controller 3 detects, based on the temperature information signal from the temperature sensor 12, that the temperature of the cutting start site P1 has risen by a predetermined temperature ΔT above the temperature at which cutting oxygen was injected. In step S7, when the temperature of the cutting start site P1 rises by a predetermined temperature ΔT above the temperature at which cutting oxygen was injected, the control returns to step S4, and the controller 3 controls the gas control panel 6 to inject cutting oxygen A2 from the torch 11.

[0051] Steps S4 to S7 are repeated in step S5 until, after the injection of cutting oxygen A2, the temperature of the cutting start site P1 rises and it is determined that the oxidation reaction is progressing.

[0052] If it is determined in step S5 that the temperature of the cutting start site P1 has risen, the control proceeds to step S8.

[0053] In step S8, the controller 3 initiates cutting. The controller 3 operates the robot body 13 by transmitting a drive command signal, moving the torch 11 in the cutting direction D.

[0054] In step S9, when the torch 11 has been moved a pre-programmed distance and the cutting is complete, in step S10, the controller 3 stops the cutting oxygen. The controller 3 closes the cutting oxygen solenoid valve 45 by transmitting a close command signal. This stops the injection of cutting oxygen A2 from the cutting oxygen nozzle 11b of the torch 11.

[0055] Next, in step S11, the controller 3 extinguishes the preheating flame. The controller 3 closes the solenoid valve 41 for combustible gas and the solenoid valve 43 for preheating oxygen by transmitting a close command signal. As a result, the preheating flame A1 from the preheating flame nozzle 11a of the torch 11 is extinguished, and the gas control is terminated.

[0056] As described above, in the gas cutting device 1 of this embodiment, the controller 3 injects cutting oxygen A2 from the torch 11 while the preheating flame A1 is being injected from the torch 11, and starts cutting when the temperature detected by the temperature sensor 12 rises.

[0057] When the temperature rises in this way, it can be determined that the cutting start point P1 has reached a temperature at which cutting can begin (a temperature at which the oxidation reaction proceeds), and thus cutting can be started. As a result, even if the object to be cut is a casting and there are variations in dimensions and surface finish unique to castings, the appropriate preheating time can be automatically adjusted for each cut by checking the temperature change. Because the appropriate preheating time can be automatically adjusted, gouging due to overheating is suppressed and the cut surface can be made smooth. Because the cut surface can be made smooth, the removal process by subsequent processes (arc gouging, grinding, etc.) can be reduced, and costs can be reduced. It is also possible to prevent problems such as cutting not being able to start due to insufficient preheating. A slight misalignment when fixing the workpiece W to the table 7 can be tolerated, so a dedicated jig for high-precision misalignment prevention is not required, or the jig can be simplified. In addition, because the appropriate preheating time can be automatically adjusted, the condition setting work using actual castings with a lot of variation is not required, and the man-hours required for adjusting the preheating time when starting up individual products can be greatly reduced. Furthermore, when the unwanted portion W2 has a curved shape as shown in Figure 5(b), it is more difficult to perform local heating compared to the unwanted portion W2 having an edge shape as shown in Figure 5(a), making it difficult to set a preheating time. However, with the gas cutting device 1 of this embodiment, it is not necessary to set a fixed preheating time. Therefore, in order to facilitate the start of cutting, it is not necessary to change the shape of the unwanted portion W2 to have an edge shape that facilitates local heating.

[0058] In the gas cutting device 1 of this embodiment, the controller 3 stops the injection of cutting oxygen A2 from the torch 11 when the temperature of the cutting start site P1 decreases after the cutting oxygen A2 has been injected from the torch 11.

[0059] When the temperature drops in this way, it can be determined that the cutting start point P1 has not reached the temperature at which the oxidation reaction can proceed, so the cutting oxygen A2 can be automatically stopped and the temperature can be raised again.

[0060] In the gas cutting apparatus 1 of this embodiment, the controller 3 stops the injection of cutting oxygen A2 from the torch until the temperature rises due to the injection of cutting oxygen A2, and then repeats the process of injecting cutting oxygen A2 from the torch 11 again after the temperature has risen to a predetermined temperature ΔT.

[0061] In this way, by checking the temperature change associated with the injection of cutting oxygen A2, the appropriate preheating time can be adjusted.

[0062] In the gas cutting device 1 of this embodiment, when the temperature of the preheating flame A1 is injected from the torch 11 and the temperature reaches a predetermined threshold temperature T1 or higher, the controller 3 injects cutting oxygen A2 from the torch 11.

[0063] The predetermined initial threshold temperature T1 is set lower than the temperature at which cutting is expected to begin. This eliminates the need to inject cutting oxygen A2, which inhibits preheating, while the material is preheating to the predetermined threshold temperature T1, thus shortening the preheating time. Even when long preheating times are required due to misalignment between the cutting start point P1 and the torch 11 or the condition of the casting surface (such as sand adhering), the automatic adjustment of this invention allows for stable cutting to begin.

[0064] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention.

[0065] In the gas cutting apparatus 1 of the above embodiment, as shown in Figure 5(b), the torch 11 is moved in the cutting direction D without changing the orientation of the torch 11 relative to the workpiece W, but this is not the only option. For example, if the unwanted portion W2 is cylindrical or otherwise difficult to heat locally, the orientation relative to the workpiece W may be changed between preheating and cutting, as shown in Figure 9. Figure 9 is a diagram illustrating the change in the orientation of the torch.

[0066] In the preheating position Q1, the torch 11 preheats the cutting start point P1 on the surface of the unwanted portion W2. The preheating position Q1 is the position of the torch 11 such that the direction of the preheating flame A1 is perpendicular to the tangent to the cutting start point P1 of the unwanted portion W2. In the cutting position Q2, the torch 11 moves in the cutting direction D relative to the workpiece W to perform the cutting. The cutting position Q2 is the position of the torch 11 such that the direction of the cutting oxygen A2 is aligned with the tangent to the cutting start point P1.

[0067] Controller 3 preheats the cutting start point P1 by injecting a preheating flame A1 with the torch 11 in the preheating position Q1. When a predetermined threshold temperature T1 is reached, it changes to the cutting position Q2 and injects cutting oxygen A2. If the temperature of the cutting start point P1 rises due to the injection of cutting oxygen A2, Controller 3 moves the torch 11 in the cutting direction C while in the cutting position Q2 and performs the cut. On the other hand, if the temperature of the cutting start point P1 falls due to the injection of cutting oxygen A2, Controller 3 returns the torch 11 to the preheating position Q1, and when the temperature rises to a predetermined temperature ΔT, it changes the torch 11 to the cutting position Q2 and injects cutting oxygen A2 again, and determines whether the temperature of the cutting start point P1 rises or falls.

[0068] By preheating from the normal direction perpendicular to the tangent line L in this way, preheating can be performed efficiently. In addition, when injecting the cutting oxygen A2, the torch 11 is set to the cutting position Q2, which prevents the slag from bouncing back towards the torch 11.

[0069] In the above embodiment, it is only stated that the torch 11 is positioned to face the cutting start point P1, but the position of the torch 11 during preheating may be adjusted. For example, as shown in Figure 10(a), the controller 3 positions the torch 11 at a distance F away from the cutting start point P1 of the workpiece W at position P2. The controller 3 moves the torch closer to the cutting start point P1 of the workpiece W by a predetermined distance while detecting the heating rate (see arrow E). The controller 3 stores the heating graph of the cutting start point P1 when the torch 11 is positioned in an appropriate position for preheating. Figure 10(b) shows the heating graph G11 (dotted line) of the cutting start point P1 when the torch 11 is positioned in an appropriate position for preheating. A predetermined threshold temperature T1 is shown in Figure 10(b). For example, when the torch 11 is positioned at a distance F away, the temperature of the cutting start point P1 changes as shown in graph G12 (solid line).

[0070] If the heating rate is slower than the stored heating rate graph G11, the controller 3 moves the torch 11 closer to the workpiece W by a predetermined distance. The controller 3 moves the torch 11 toward the workpiece W by a predetermined distance so that the difference between the stored heating rate and the heating rate detected by the temperature sensor 12 falls within a predetermined range. This allows the position of the torch 11 to be adjusted to an appropriate position for preheating. Graph G13 (dotted line) shows the temperature change when the torch 11 is moved toward the workpiece W by a predetermined distance while detecting the heating rate. In this way, by moving by a predetermined distance, the heating rate can be brought closer to the heating rate in the stored heating rate graph G11, thus allowing the position of the torch 11 to be adjusted to an appropriate position for preheating.

[0071] In the above embodiment, a predetermined threshold temperature T1 is provided, but a threshold temperature T1 does not necessarily have to be provided. For example, after a predetermined time has elapsed from the start of preheating, cutting oxygen A2 may be injected and the temperature change may be determined.

[0072] In the above embodiment, cutting oxygen A2 is injected from the torch 11 each time the temperature rises to a predetermined temperature ΔT, and it is determined whether or not the temperature of the cutting start site P1 rises. However, this is not limited to temperature; it may also be determined by time. That is, cutting oxygen A2 may be injected from the torch 11 at predetermined time intervals, and it may be determined whether or not the temperature of the cutting start site P1 rises.

[0073] In the above embodiment, a radiation thermometer was used as a temperature sensor to capture the oxidation reaction associated with the discharge of cutting oxygen A2. However, the thermometer is not limited to this, as long as it can capture the oxidation reaction, a brightness sensor or a sound sensor may be used instead of, or in addition to, the temperature sensor. A brightness sensor can capture the oxidation reaction by detecting the light emitted during the oxidation reaction. A sound sensor can capture the oxidation reaction by detecting the sound produced during the oxidation reaction. [Industrial applicability]

[0074] The gas cutting apparatus of this disclosure has the effect of automatically adjusting to an appropriate preheating time for each cut, and is useful, for example, when gas cutting castings. [Explanation of Symbols]

[0075] 1: Gas cutting device 3: Controller 11: Torch A1: Preheating flame A2: Oxygen for cutting

Claims

1. A gas cutting device for cutting a predetermined part of an object, A torch capable of spraying preheating flame and cutting oxygen, A temperature sensor for detecting the temperature of the cutting start site of the object, The system includes a controller that initiates cutting when the temperature rises while the preheating flame is being ejected from the torch and cutting oxygen is being ejected from the torch. Gas cutting device.

2. The controller stops the injection of cutting oxygen from the torch when the temperature drops while the cutting oxygen is being injected from the torch. The gas cutting apparatus according to claim 1.

3. The controller, when the cutting oxygen is injected from the torch, stops the injection of the cutting oxygen from the torch until the temperature rises, and then repeats the injection of the cutting oxygen from the torch after the temperature has risen to a predetermined temperature. The gas cutting apparatus according to claim 2.

4. The controller, when the preheating flame is being ejected from the torch, ejects the cutting oxygen from the torch when the temperature exceeds a predetermined threshold temperature. The gas cutting apparatus according to claim 1.

5. The torch is further provided with a torch movement unit that can move between a preheating position for preheating the object and a cutting position for cutting the object, The controller controls the torch movement unit so that when the preheating flame is ejected from the torch, the torch is in the preheating position, and when the cutting oxygen is ejected from the torch, the torch is in the cutting position. The gas cutting apparatus according to claim 1.

6. The system further includes a torch moving unit that moves the torch relative to the object, The controller, while injecting the preheating flame from the torch until the temperature reaches or exceeds the predetermined threshold temperature, moves the torch relative to the object if the rate of temperature increase is slower than a predetermined rate of temperature increase set in advance, so that the rate of temperature increase becomes faster than the predetermined rate of temperature increase. The gas cutting apparatus according to claim 4.

7. The system further includes a torch moving unit that moves the torch relative to the object, The temperature sensor is a radiation temperature sensor, The temperature sensor is connected to the torch and moves together with the torch by the torch moving part. The gas cutting apparatus according to claim 1.

8. A gas cutting method for cutting a predetermined part of an object, To emit a preheated flame from the torch, In the state in which the preheating flame is being ejected from the torch, cutting oxygen is ejected from the torch, The temperature of the cutting start point of the object is detected, The system includes the function of initiating cutting when the temperature rises after the cutting oxygen is injected from the torch, Gas cutting method.

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