JP4878985B2 - Thermal cutting machine and thermal cutting method - Google Patents

Description

  The present invention relates to a thermal cutting machine represented by a plasma cutting machine, and more particularly to a technique for setting a distance from a base material to a nozzle.

  Taking plasma cutting as an example, in plasma cutting, it is good to keep the distance from the surface of the base material (contacted member) to the tip of the plasma torch (nozzle) (hereinafter “stand-off”) at an appropriate value. It is important to obtain a good cutting quality. A control method for maintaining a constant standoff is called a control method (AVC (Arc Voltage Control or Automatic Voltage Control)) that uses an arc voltage that changes as the arc length increases or decreases according to the magnitude of the standoff. ) Is common.

  In the plasma arc cutting process in AVC, if an arc is generated, the standoff can be detected by the arc voltage, but naturally the arc voltage cannot be used before the arc is generated. Therefore, at the start of cutting, first, the height (vertical position) of the base material is measured, and an appropriate standoff is set by separating the nozzle from the vertical position of the base material by a predetermined distance. The height of the plasma torch at this time (hereinafter, “torch height”) is the initial torch height. The following methods are known as methods for measuring the height of a base material. That is, when a voltage of several volts was applied between the nozzle and the base material, and when the nozzle and the base material contacted, a current flowed between the nozzle and the base material (or the voltage decreased). The height of the base material is measured by detecting. Moreover, what measures the height of a base material using a position sensor is also known (patent document 1).

  The stand-off in the cutting process changes depending on the thickness of the base material, and even if the thickness is the same, it changes depending on the inclination and warpage of the base material. Therefore, the initial torch height ends after one cutting process. It must be set every time a new cutting is started.

JP 2001-198679 A

  The initial torch height setting method as described above is effective in normal cutting (cutting in the first pass) in which a product is simply cut out from the base material. However, after the product is cut out from the base material by cutting in the first pass, as in the case where some kind of groove processing is performed on the product, the cut product is further cut (cut in the second pass or In situations where subsequent cutting) is necessary, a malfunction occurs.

  This problem will be described with reference to FIGS. As shown in FIG. 1, after the cutting of the first pass is finished, the product 104 to be cut in the second pass is completely separated from the base material 103. Here, the upper surface of the cutting table on which the base material 103 is placed has irregularities due to dross adhesion or melting due to the cutting performed so far. For this reason, the height of the product 104 may deviate from the height of the base material 103.

  On the other hand, when starting the second pass cutting, if the product 104 is suddenly cut from the end face, the product 104 may be damaged, so the second pass cutting is started on the base material 103 side and the first pass from there. The product is cut into the product 104 across the cutting groove 105. Therefore, the cutting line in the second pass is an extension of the cutting line in the product 104 to the base material 103 side. For example, as shown in FIG. 1, broken lines connecting points A and B on the base material 103 side, and points A ′ and B ′ are the cutting lines 106 in the second pass.

  FIG. 2A is a cross-sectional view of the cutting line 106 in the second pass connecting the points A and B. FIG. As can be seen from the figure, the product 104 is lower than the base material 103 on the point A side, with the cutting groove 105 in the first pass as a boundary. Therefore, when cutting is started from point A, the plasma torch 101 that has moved while maintaining a certain standoff 201 with respect to the base material 103 is too far from the product 104 at the moment it moves to the product 104. Will end up. FIG. 2B is a cross-sectional view of the second-pass cutting line 106 connecting the points A ′ and B ′. In this case, the product 104 is higher than the base material 103 on the A ′ point side, with the cutting groove 105 in the first pass as a boundary, contrary to FIG. Therefore, when cutting is started from point A ′, the plasma torch 101 that has moved while maintaining a certain standoff 201 with respect to the base material 103 is too close to the product 104 at the moment it moves to the product 104. It will end up. Further, in this case, the plasma torch 101 collides with the product 104 depending on the situation.

  In this way, in the second pass or subsequent cuts, there is a difference in height between the base material 103 where the cutting is started and the product 104, so that the standoff is inappropriate when the cutting of the product 104 starts. Value. The initial torch height setting method as described above is to set the torch height so that the standoff becomes an appropriate value at the cutting start point, that is, the base material 103, and the above problems are considered. Not.

  Therefore, the object of the present invention is to cut the second pass or later while maintaining an appropriate stand-off when the second pass or later is required as in the case of performing groove processing. Is to be able to do it.

  The thermal cutting machine according to one aspect of the present invention cuts a product from a base material by cutting a first pass, and starts cutting from the base material side by cutting a second pass after the cutting of the first pass. And a torch control means for controlling the position of the torch, and at least one predetermined position on the product in a thermal cutting machine for cutting the cut product through the cutting groove generated by the cutting of the first pass A height measuring means for measuring the height of the product and the height of the base material at the cutting start position of the second pass on the base material, the torch control means in the second pass cutting, While moving the torch along the cutting line, when the torch reaches the cutting groove, based on the difference between the height of the product and the height of the base material measured by the height measuring means, Of the torch To change the of.

  In a preferred embodiment, when the height of the product is lower than the height of the base material, the torch control means moves the torch vertically downward by the difference when the torch reaches the cutting groove. If the product is moved and the height of the product is higher than the height of the base material, the torch may be moved vertically upward by the difference when the torch reaches the cutting groove.

  In a preferred embodiment, the predetermined position at which the height of the product is measured is a point selected from a point closest to the cutting start position on the cutting line of the second pass or a predetermined area close to the point. It may be.

  According to the present invention, when the second pass or later is required as in the case of performing groove processing, the second pass or later can be cut while maintaining an appropriate stand-off. .

  Hereinafter, a thermal cutting machine according to an embodiment of the present invention applied to a plasma cutting machine will be described with reference to the drawings.

  FIG. 3 is a perspective view showing the structure of the plasma cutting machine 301 according to the present embodiment.

  A steel plate as the base material 103 is placed horizontally on the cutting table 302. A Y carriage 305 is installed so as to be horizontally movable in the Y direction with respect to the cutting table 302. A guide rail 303 projects from the Y carriage 305 in the X direction, and the X carriage 304 can move horizontally on the guide rail 107 in the X direction. A Z carriage 306 that moves in the Z (vertical) direction is attached to the X carriage 304, and the plasma torch 101 is fixed to the Z carriage 306 facing downward.

  While the base material 103 is being cut, the plasma torch 101 is shaped into the shape of the product 104 while maintaining a certain standoff with respect to the base material 103 by the XYZ moving system including the carriages 304, 305, and 306. It is horizontally moved in the X and Y directions along the matched processing line.

  FIG. 4 is a functional block diagram of the plasma cutting machine 301 according to the present embodiment.

  The plasma cutting machine 301 according to the present embodiment includes a controller 401, a torch control mechanism 402, a power supply 403, and a gas supply system 404.

  The controller 401 controls the entire plasma cutting machine 301. For example, the controller 401 activates the power supply 403, supplies gas from the gas supply system 404, and generates the plasma arc 102 from the plasma torch 101. In addition, the controller 401 operates the torch control mechanism 402 in a state where the plasma arc 102 is generated, thereby moving the plasma torch 101 along a pre-programmed XY system trajectory, thereby moving the base material 103. Disconnect. At this time, the controller 401 adjusts the plasma torch 101 by moving the plasma torch 101 in the vertical direction by following the height by the AVC so that an appropriate stand-off is maintained.

  Further, the controller 401 measures the height of the base material 103 before starting the first-pass cutting for cutting out the product 104 from the base material 103. That is, as described above, a method of detecting a change in voltage by applying a constant voltage between the nozzle and the base material 103 and bringing the nozzle and the base material 103 into contact with each other or a position sensor is used. The height of the base material 103 is measured by a method or the like. Based on the measured height of the base material 103, the controller 401 determines an initial torch height for cutting the first pass. For example, the initial torch height is determined as the height of the base material 103 plus an appropriate standoff value that is held in advance.

  Further, when the second cut (or later) is performed on the product 104 cut out from the base material 103, the controller 401 measures the height of each of the product 104 and the base material 103 and then the base material. The second pass (or later) cutting is started from the side of 103, and the standoff of the plasma torch 101 with respect to the base material 103 is controlled based on the height of the base material 103. And the product 104, the plasma torch 101 is moved in the vertical direction on the basis of the height difference between the base material 103 and the product 104 when passing through the first-pass cutting groove 105 between the product 104 and the product 104. To ensure proper stand-off. Details of this will be described later.

  The torch control mechanism 402 moves the plasma torch 101 to a position designated by the controller 401. That is, the torch control mechanism 402 moves the plasma torch 101 to a position designated by the controller 401 by controlling the X carriage 304, the Y carriage 305, and the Z carriage 306 and moving them.

  The power source 403 is used to generate the plasma arc 102. The base material 103 is cut by the plasma arc 102. The power supply 403 applies a voltage between the nozzle and the base material 103 when detecting a change in the voltage between the nozzle and the base material 103 to obtain the height of the base material 103 and the product 104. Used for.

  The gas supply system 404 supplies a gas necessary for generating the plasma arc 102. This gas supply is performed under the control of the controller 401.

  A description will be given of a procedure in which the plasma cutting machine 301 configured as described above performs the second pass cutting while maintaining an appropriate standoff 201 in consideration of the height difference between the base material 103 and the product 104. (The same applies when cutting after the third pass).

  FIG. 5 is a diagram showing the movement of the plasma torch 101 in the second-pass cutting.

  FIG. 4A shows a state where the plasma torch 101 controlled by the controller 401 moves on the XY plane. Each point (point A, point B, point S, point T) shown in the figure represents a position on the XY plane. On the other hand, FIG. 5B is a cross-sectional view passing through the points A and S, and represents the height of the base material 103 and the product 104. In this figure, the height is defined with the bottom surface of the cutting table 302 as the origin of the Z axis, but this is merely for convenience of explanation, and where the controller 401 places the origin of the Z axis is The controller 401 is free. Therefore, the height of the base material 103 at point A is represented by reference numeral 502, and the height of the product 104 at point S is represented by reference numeral 503. FIG. 6C is a cross-sectional view passing through the points A and B, and shows the movement of the plasma torch 101 in the Z-axis direction while the plasma torch 101 moves from the point A to the point B. Yes.

  First, the movement of the plasma torch 101 on the XY plane will be described with reference to FIG.

  After cutting the first pass, the plasma torch 101 is moved to the S point on the product 104 side. The point S is an arbitrary point selected from a predetermined region (hereinafter, “neighboring region”) 501 of the product 104 close to the point where the cutting line 106 of the second pass enters the product 104. As can be seen from the description below, the point S is a representative point on the product side that is used to obtain the height difference between the base material 103 on the side A and the product 104 in the cutting line 106 in the second pass. Therefore, in order to obtain a more accurate height difference, the closer to the point A on the base material 103 that is the cutting start point of the second pass, the better the closer to the cutting line 106 of the second pass. Furthermore, if the point closest to the point A (nearest point) is the S point, the most accurate height difference can be obtained. On the other hand, the product 104 is planar, and even if the product 104 is separated from the base material 103 and tilted with respect to the XY plane, the tilt is not so large. Therefore, the difference between the height of the product 104 at the closest point and the height of the product 104 at a point selected from the vicinity thereof is not so large. For this reason, in the present embodiment, as described above, an arbitrary point selected from the neighborhood region 501 is set as an S point that is a representative point on the product side.

  Here, the method as described above, that is, a method in which a constant voltage is applied between the nozzle and the base material 103, and a change in the voltage is detected by bringing the nozzle and the base material 103 into contact with each other. The height (hereinafter simply referred to as “product height”) 503 of the product 104 at the point S is measured by a method using a sensor or the like.

  Next, the plasma torch 101 is moved from point S to point A on the base material 103, which is the cutting start point of the second pass. Again, the height of the base material 103 at point A (hereinafter simply referred to as “base material height”) 502 is measured by the same method as described above. Further, the initial torch height in the second pass cutting is also determined based on the base material height 502.

  Thereafter, the plasma cutting machine 301 activates the power source 403 to generate the plasma arc 102 between the plasma torch 101 and the base material 103, and makes a hole at point A. Then, the plasma cutting machine 301 moves the plasma torch 101 from the point A to the point B while maintaining the state in which the plasma arc 102 is generated, and cuts the product 104 along the second-pass cutting line 106. Hereinafter, the movement of the plasma torch 101 in the Z-axis direction during cutting will be described with reference to FIG.

  After the base material height 502 is measured at point A, the height of the plasma torch 101 is set to the initial torch height (here, the base material height 502 plus the appropriate value of the standoff 201).

  Thereafter, as described above, a hole is made at point A by the plasma arc 102 and cutting is performed along the cutting line 106 in the second pass. Here, in the cutting line 106 in the second pass, there is a height difference between the base material 103 and the product 104 as shown in FIG. The plasma cutting machine 301 in this embodiment controls the torch height as follows in order to perform cutting while maintaining an appropriate stand-off in consideration of this height difference.

  That is, while the plasma torch 101 moves from the point A to the point B while maintaining a constant standoff 201 with respect to the base material 103, T is a boundary point between the base material 103 and the first-pass cutting groove 105. When moving to the point, the controller 401 changes the torch height by a difference 504 (hereinafter simply referred to as “difference”) 504 between the base material height 502 and the product height 503. Specifically, when the product height 503 is lower than the base material height 502 (as shown in FIG. 5C), the controller 401 determines the torch height when entering the point T (the torch before the change). The value obtained by subtracting the difference 504 from (high) is set as the changed torch height. That is, as shown in FIG. 6C, the plasma torch 101 is moved vertically by a difference 504 at the point T. On the contrary, when the product height 503 is higher than the base material height 502, the controller 401 sets a value obtained by adding the difference 504 to the torch height before the change as the torch height after the change. That is, in this case, the plasma torch 101 is moved by the difference 504 vertically upward at the point T. Thereby, the changed torch height is a height obtained by adding the appropriate value of the standoff 201 to the product height 503. Strictly speaking, a certain amount of error occurs, but it does not cause a problem. This error occurs because the base material 103 also has a slight inclination with respect to the XY plane, and the torch height at the point T changes compared to the initial torch height at the point A due to the height copying by the AVC. This is because the points A and T are not so far apart. As a result, after that, when the plasma torch 101 passes through the first-pass cutting groove 105 and the cutting of the product 104 is started, the proper standoff 201 can be maintained for the product 104 as well. .

  Here, when the plasma torch 101 moves to the point T which is the boundary point between the base material 103 and the cutting groove 105 in the first pass, the torch height is changed based on the difference 504. The position to be changed is not limited to this. It is sufficient that the torch height after the change is reached when the cutting of the product 104 is started. That is, there is some time lag from when the controller 401 issues a command to operate the torch control mechanism 402 to when the torch height actually changes, and the plasma torch 101 moves during that time. The position where the torch height is changed may be determined in consideration of the time lag and the moving speed of the plasma torch 101.

  After the cutting of the product 104 is started, the plasma torch 101 is moved to the point B along the cutting line 106 in the second pass while maintaining an appropriate stand-off for the product 104 by the height copying by the AVC. Is moved.

  FIG. 6 is a diagram illustrating a processing flow when the plasma cutting machine 301 according to the present embodiment performs the second-pass cutting.

  First, after cutting of the first pass is completed (S601), the plasma torch 101 is moved to the point S and the product height 503 is measured (S602). Next, the plasma torch 101 is moved to point A, and the base material height 502 is measured (S603).

  Thereafter, the height of the plasma torch 101 is set to the initial torch height determined based on the base material height 502, and the second-pass cutting is started (S604). At the time of cutting, the plasma torch 101 is moved along the cutting line 106 of the second pass while maintaining an appropriate stand-off by following the height by AVC (S605).

  If the cutting groove 105 of the first pass is reached (S606: YES), the torch height is changed based on the difference 504. That is, when the product height 503 is smaller than the base material height 502 (S607: YES), the height of the plasma torch 101 is changed by setting the value obtained by subtracting the difference 504 from the torch height before the change as the torch height after the change. (S608). On the other hand, when the product height 503 is larger than the base material height 502 (S607: NO), the height of the plasma torch 101 is changed by setting the value obtained by adding the difference 504 to the torch height before the change as the torch height after the change. (S609).

  Thereafter, again, the plasma torch 101 is moved along the cutting line 106 of the second pass while maintaining an appropriate stand-off by height copying by AVC (S610). The cutting is completed when the plasma torch 101 reaches point B, which is the end point of the cutting line 106 in the second pass.

  By performing the processing as described above, when the second pass or a subsequent cut is required, as in the case of performing groove processing, the second pass or more while maintaining an appropriate standoff. Subsequent cutting can be performed.

  The above-described embodiments of the present invention are examples for explaining the present invention, and are not intended to limit the scope of the present invention only to those embodiments. The present invention can be implemented in various other modes without departing from the gist thereof. For example, in the present embodiment, the product height 503 is determined using any one point selected from the neighborhood region 501 as a representative point on the product 104 side. However, the product 104 is measured by measuring the height of a plurality of points on the product 104 side. The height at the closest point can be calculated from these, and the height at the closest point can be set as the product height 503. As a result, the difference 504 with higher accuracy can be obtained.

It is the figure which showed typically the positional relationship of the base material and product in the cutting | disconnection of the 2nd pass. It is sectional drawing of the cutting line of the 2nd pass. It is the perspective view which showed the structure of the plasma cutting machine which concerns on this embodiment. It is a functional block diagram of the plasma cutting machine concerning this embodiment. It is the figure which showed the motion of the plasma torch in the 2nd cutting | disconnection. It is the figure which showed the flow of the process at the time of the plasma cutting machine which concerns on this embodiment cut | disconnects the 2nd pass.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Plasma torch, 102 ... Plasma arc, 103 ... Base material, 104 ... Product, 105 ... Cutting groove of 1st pass, 106 ... Cutting line of 2nd pass, 201 ... Stand-off, 301 ... Plasma cutting machine, 302 ... Cutting table, 303 ... guide rail, 304 ... X carriage, 305 ... Y carriage, 306 ... Z carriage, 401 ... controller, 402 ... torch control mechanism, 403 ... power supply, 404 ... gas supply system, 501 ... near area, 502 ... Base material height, 503 ... Product height, 504 ... Difference

Claims (3)

A cut groove formed by cutting the first pass by cutting a product from the base material by cutting the first pass, starting cutting from the base material side by cutting the second pass after the cutting of the first pass In a thermal cutting machine that cuts the cut product past the
Torch control means for controlling the position of the torch;
The most cutting start position near the point on the second pass of the cutting line or selected from a predetermined region close to the point, the height of the product in the product on the near-Ru Jo Tokoro position, the base material on A height measuring means for measuring the height of the base material at the cutting start position of the second pass at
In the cutting of the second pass, the torch control means moves the torch along the cutting line, and when the torch reaches the cutting groove, the torch control means measures the product measured by the height measuring means. A thermal cutting machine that changes a height of the torch based on a difference between a height and a height of the base material.   When the height of the product is lower than the height of the base material, the torch control means moves the torch vertically downward by the difference when the torch reaches the cutting groove, The thermal cutting machine according to claim 1, wherein, when the height is higher than the height of the base material, the torch is moved vertically upward by the difference when the torch reaches the cutting groove. A cut groove formed by cutting the first pass by cutting a product from the base material by cutting the first pass, starting cutting from the base material side by cutting the second pass after the cutting of the first pass In a thermal cutting method of cutting the cut product past the
Measuring the height of the product in the most cutting start position near the point or place Ru said product on near selected from a predetermined region close to the point on the cutting line of the second pass,
Measuring the height of the base material at the cutting start position of the second pass on the base material;
Setting the torch to a predetermined height and starting cutting the second pass;
While moving the torch along the second-pass cutting line, when the torch reaches the cutting groove, based on the difference between the measured height of the product and the height of the base material, Changing the height of the torch.

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