JPH035081A - Plasma cutting device - Google Patents

Abstract

PURPOSE:To form a section of a work at a right angle by generating magnetic fields by plural couples of magnetic field generation means and controlling the magnetic field generation means so that the deflecting direction of a plasma arc is always made to the optimum direction with respect to the moving direction of a torch. CONSTITUTION:One couple of exciting coils 17a and 17b and one couple of exciting coils 19a and 19b are arranged in the X direction and the Y direction respectively in opposition to a nozzle 62 of a lower end of the torch 16. These exciting coils are fixed on the nozzle 62 via magnetic path forming members 21a, 21b, 23a and 23b of the respective tips. The nozzle 62 is made of copper and has no effect on the magnetic fields. The direction of a deflection angle thetas of the plasma arc is regulated and the section of a part 6A to be cut off is formed at the right angle by controlling a current to the two couples of exciting coils. The need for a rotating mechanism to rotate the torch is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma cutting device, and particularly to one in which the direction of deflection of a plasma arc deflected by the action of a magnetic field is changed in accordance with the direction of movement of a torch.

[Prior art]

2. Description of the Related Art In general, plasma cutting devices are already known that fuse and cut metal or non-metallic materials by concentrating the energy of a plasma arc generated by a cutting torch (hereinafter referred to as a torch) on a cutting local area.

However, in normal plasma cutting in which the torch is set perpendicular to the workpiece, the degree of melting on the upper surface of the workpiece is greater than the degree of melting on the lower surface, resulting in a large cutting bevel angle and The cut plane of the cut part is not perpendicular to the workpiece. Therefore, an extra work step is required to square the cut surface.

Therefore, for example, in Japanese Patent Application Laid-Open No. 49-13062,
A plasma cutting method is described in which a magnetic field is applied to a plasma arc ejected from a torch to deflect the plasma arc toward the part, thereby forming a cut surface perpendicular to the part.

However, this plasma cutting method merely discloses a technique for deflecting the plasma arc by the action of a magnetic field, and the deflection direction of the plasma arc is constant, and the parts cannot be cut in a specific direction or speed of the torch. However, when cutting in a direction other than the specific movement direction of the torch, such as when cutting corners or curves, or when the moving speed of the torch changes, the cut surface may be formed at a right angle. cannot be formed.

Therefore, in Japanese Patent Application No. 1-71043, the applicant attached a magnetic field generator to the plasma torch, and rotated the magnetic field generator alone or together with the torch depending on the direction of movement of the torch to control the deflection direction of the plasma arc. We proposed a plasma cutting device that rotates around a vertical axis and forms all cut surfaces of parts at right angles.

(Problems to be Solved by the Invention) Generally, a cutting torch is connected to a gas hose that supplies a working gas, a cooling water hose, a current supply cable that supplies a driving current to an electrode, and the like.

Therefore, in the magnetic field generator or the plasma cutting device related to the above-mentioned application of Hikari, the rotating mechanism for rotating the torch becomes large, and while rotating the torch, the working gas or cooling water from the gas hose is transferred to the torch. There are problems such as the complexity of the connection structure for supplying.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma cutting device that can form all cut surfaces of parts cut from a work at right angles with a simple configuration.

[Means to solve the problem]

A plasma cutting device according to the present invention includes a cutting torch that cuts a workpiece with a plasma arc ejected from a nozzle at its tip, a moving means that moves the cutting torch relative to the workpiece, and a device that generates a magnetic field and It is equipped with a magnetic field generating means that causes this magnetic field to act on the plasma arc, and a drive control means that numerically controls the moving means based on cutting processing information inputted in advance, while moving the cutting torch relative to the workpiece. In a plasma cutting device that cuts a workpiece by deflecting a plasma arc in a plane orthogonal to the magnetic field,
A plurality of sets of magnetic field generating means that generate mutually crossing magnetic fields are provided as magnetic field generating means, and upon receiving cutting processing information and information regarding the position of the cutting torch from the drive control means, the deflection direction of the plasma arc is always adjusted to the direction of torch movement. The apparatus is equipped with a control means for controlling a plurality of sets of magnetic field generation means so as to be in the optimum direction with respect to the direction.

[Effect]

In the plasma cutting apparatus according to the present invention, the drive control means numerically controls the moving means based on cutting processing information to move the cutting torch relative to the workpiece. At this time,
A plurality of sets of magnetic field generating means each generate a magnetic field that intersects with each other, and the magnetic field acts on the plasma arc ejected from the cutting torch. here,
The magnetic field generated from each magnetic field generating means can be expressed as a magnetic field hector having the strength and direction of the magnetic field, and one composite magnetic field vector is obtained from a plurality of magnetic field vectors. That is,
By controlling the strength and direction of each magnetic field vector, the direction of this composite magnetic field vector can be easily deflected over 360 degrees around the vertical axis, and the plasma arc is deflected in a plane perpendicular to this composite magnetic field. be done.

On the other hand, when plasma cutting is started, the control means receives cutting processing information and information regarding the position of the cutting torch from the drive control means, so that the deflection direction of the plasma arc is always the part to be cut with respect to the moving direction of the cutting torch. The plurality of sets of magnetic field generating means are controlled so as to face in the optimum direction toward the side. As a result, the direction of the combined magnetic field is controlled according to the direction of movement of the torch, and the cut surface of the part is always formed at right angles to the top surface of the part from the top surface to the bottom surface of the part by the plasma arc.

This eliminates the need for a rotation mechanism for rotating the magnetic field generator or the torch, and further simplifies the connection structure for connecting the working gas hose, cooling water hose, etc. to the torch.

〔Effect of the invention〕

According to the plasma cutting device according to the present invention, as explained in the [Operation] section, a plurality of sets of magnetic field generators are provided, and these magnetic field generators are controlled so that the direction of deflection of the plasma arc is always controlled by the movement of the torch. Since it can be deflected in the optimum direction toward the part to be cut, the cut plane of the part, including corners and curves, can always be formed at right angles.

Furthermore, it is possible to eliminate the need for a rotation mechanism for rotating the magnetic field generator or the torch, and to simplify the connection structure for connecting the working gas hose, cooling water hose, etc. to the torch.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a plasma cutting apparatus 1 that can numerically control the movement of cutting 1-chies (hereinafter referred to as 1-chies), and this plasma cutting apparatus 1 will be explained.

A pair of left and right guide rails 2 and 4 extending in the front-rear direction have a rectangular cross section and are laid parallel to each other on the floor at a predetermined distance apart, and a rack is formed on the inner surface of the left guide rail 2. A member 8 is attached over substantially its entire length. A workpiece 6 for cutting is arranged between the pair of guide rails 2 and 4.

On the pair of guide rails 2 and 4, a torch moving frame 28, which is gate-shaped when viewed from the front, is arranged so as to be movable in the front-back direction. A moving member 10 having a substantially gate-shaped cross section and movably mounted on the guide rail 2; a moving member 12 having a similar structure to the moving member 10 and movably mounted on the guide rail 4; and a moving member 1.
A column 22 erected at 0, a column 24 erected on the moving member 12, and a pair of supports installed in the left-right direction across the upper ends of both columns 22 and 24 and separated by a predetermined distance in the front-rear direction. It is composed of members 26 and the like.

A protrusion 14 is formed on the inner surface of the moving member 10,
An X-direction servo motor 18 for moving a cutting torch (hereinafter referred to as a torch) 16 in the X direction (back and forth direction) is installed inside this protrusion 14 .
A pinion (path shown) attached to the drive shaft of the rack member 8 meshes with the rack of the rack member 8. Incidentally, reference numeral 2o is provided in the X-direction servo motor 18, and a feedback signal Ys(
This is an encoder that outputs (see FIG. 4). Therefore, X
As the moving member 10 moves forward and backward while being guided by the guide rail 2 by driving the direction servo motor 18 via the pinion and rack, the moving member 12 is also guided by the guide rail 4 and moves forward and backward. , the torch moving frame 28 moves in the X direction.

A drive shaft 30 is disposed across the upper ends of both columns 22 and 24 and has a spiral groove for a ball screw in the left and right direction,
Both ends of the drive shaft 30 are rotatably supported at both ends. A block member 32 is screwed onto this drive shaft 30 via a ball screw block.
A sliding engagement portion that engages with a guide portion (path shown in the drawing) formed on one support member 26 and is supported and guided is provided on the front or rear side of the support member 2 . Furthermore, a drive shaft of an X-direction servo motor 34 that moves the torch 16 in the X direction (left-right direction) is fixed to the left end of the drive shaft 3o. Incidentally, reference numeral 36 is an encoder provided on the X-direction servo motor 34 and outputting a feedback signal XS (see FIG. 4). As a result, when the X-direction servo motor 34 is driven, as the drive shaft 30 rotates, the block member 32 moves in the left-right direction via the spiral groove and the ball screw block.
The torch 16 moves in the X direction. That is, the torch 16 can be moved to a desired cutting position by the combined drive of the X-direction servo motor 18 and the X-direction servo motor 34.

As shown in FIGS. 1 to 3, a pair of excitation coils 17a and 17b are respectively disposed facing the nozzle 62 at the lower end of the torch 16 and oriented in the χ direction. An R-shaped magnetic path forming member 21 is inserted into each of these excitation coils 17a and 17b, and this magnetic path forming member 21 has both ends 21
A and 21b, that is, a pair of magnetic poles are fixed to the nozzle 62 and supported by the torch 16.

Note that this nozzle 62 is made of copper and allows the magnetic field to pass through without affecting it. This pair of excitation coils 17a and 17b
A first magnetic field generator 17 is configured. Further, a pair of excitation coils 19a and 19b are respectively disposed facing each other and in the Y direction with respect to the nozzle 62, and the magnetic path forming member 2
A magnetic path forming member 23 having an abbreviated shape similar to 1 is inserted into these excitation coils 19a and 19b, respectively, and this magnetic path forming member 23 is immediately below the magnetic path forming member 21 and is located directly below the magnetic path forming member 21. 21 is rotated 90 degrees counterclockwise in FIG. 3, and is supported by the torch 16 with both ends 23a and 23b, that is, a pair of magnetic poles, fixed to the nozzle 62, respectively. This pair of excitation coils 19a and 19b generates a second magnetic field generator 1.
9 are configured. Here, the coil winding directions of the excitation coil 17a and the excitation coil 17b are the same, and the coil winding directions of the excitation coil 19a and the excitation coil 19b are the same, and the excitation coil 17a and the excitation coil 17b are connected in series. , the excitation coil 19a and the excitation coil 19b are also connected in series. Therefore, when a driving voltage is applied to the first magnetic field generator 17 and a current flows in a predetermined direction through the excitation coils 17a and 17b, the magnetic pole 21a is excited to the S pole (or N pole), and the magnetic pole 21b is excited to the N pole ( or south pole). Furthermore, when a driving voltage is applied to the second magnetic field generator 19 and a current flows in a predetermined direction through the excitation coils 19a and 19b, the magnetic pole 23a is excited to the S pole (or N pole), and the magnetic pole 23b is excited to the N pole ( or south pole). Thereby, the magnetic field generated from the first magnetic field generator 17 and the magnetic field generated from the second magnetic field generator 19 are orthogonal to each other.

The control box 38 houses a plasma arc power supply device 42 for supplying cutting current to a drive control device 40 and the torch 16, which will be described later.

The operation panel 44 has a plurality of character keys and numeric keys for inputting torch trajectory information, specifying the material and thickness of the workpiece 6, specifying cutting conditions, etc., and the direction of the cutting path when cutting in a closed loop shape. A forward cutting key that turns the cutting direction clockwise in plan view, a reverse cutting key that turns the cutting direction counterclockwise, a cutting start switch that commands the start of cutting, and the like are provided.

Although not shown, the plasma cutting device 1 is equipped with a gas supply device for supplying working gas to the torch 16, a cooling device for cooling the nozzle 62, etc. A drive current supply cable, a current supply cable to both magnetic field generators 17 and 19, a control cable, a working gas hose, a cooling water hose, etc. are also provided to extend as the torch 16 moves.

Next, the overall configuration of the control system of the plasma cutting apparatus 1 will be explained based on the block diagram of FIG. 4.

The control system of the plasma cutting device 1 is basically an operation panel 44.
It is composed of an X direction servo motor 34, a Y direction servo motor 18, a plasma arc power supply device 42, a high frequency generator 46, a drive control device 40, etc.
CPU (central processing unit) 48, drive circuits 25 and 27
・50, 52, path 53 such as data bus to CPU 48
Input/output interface 54 connected via RO
It is composed of M56 and RAM5B.

The input/output interface 54 is connected to the operation panel 44 and the drive circuits 25, 27, 50, and 52, and
A feedback signal XS from encoder 36 and a feedback signal YS from encoder 20 are input.

The plasma arc power supply device 42 uses a commercial AC power source as an input source to generate a DC cutting current to be supplied to the electrode 60 of the torch 16 . An output regulator 64 provided in the plasma arc power supply device 42 supplies a cutting current to the electrode 60 in response to an adjustment signal AS supplied from the CPU 48 via the input/output interface 54. Here, the positive terminal of the output regulator 64 is connected to the workpiece 6, and the negative terminal thereof is connected to the electrode 60.

Therefore, 3 4 plasma currents flowing from the workpiece 6 toward the torch 16 flow through the plasma arc ejected from the nozzle 62 during cutting. At this time, both magnetic field generators 17 and
When a driving current is passed through the magnetic field generators 17 and 19, a magnetic field is generated from each magnetic field generator 17 and 19. When these magnetic fields are applied to the plasma arc, the plasma arc has a deflection angle θ5 with respect to the vertical axis, as shown in Fig. 2. is only deflected.

Here, regarding control to deflect the plasma arc in a desired direction using the magnetic fields generated from both magnetic field generators 17 and 19,
This will be explained based on FIG. Note that the X axis is the X direction, and the Y
The axis indicates the Y direction, and the intersection of the X and Y axes is the center of the nozzle 62.

The magnetic field generated from each magnetic field generator 17, 19 can be represented by a magnetic field vector having the strength and direction of the magnetic field, and a composite magnetic field vector CM can be obtained from these magnetic field vectors. In other words, as described later, the composite magnetic field vector C
Once M is determined, the magnitude GMX of the magnetic field vector generated by the first magnetic field generator 17 is G M X = G Mco
The magnitude GMY of the magnetic field vector generated by the second magnetic field generator 19, which is determined by sθ, is G MY = G Msi
It is determined by nθ.

The current value supplied to each of the magnetic field generators 17 and 19 is determined according to the magnitudes GMX and GMY of the magnetic field vectors. Note that the direction of the current supplied to each of the magnetic field generators 17 and 19 is determined by the direction of the composite magnetic field vector CM. When this composite magnetic field vector GM is applied to the plasma current, a Lorentz force acts on the plasma current, and the plasma arc moves to the left in a plane perpendicular to the composite magnetic field with respect to the vertical axis, that is, in the direction of the composite magnetic field vector GM. It is deflected by a deflection angle θ5. Therefore, by controlling both the magnetic field generators 17 and 19, the deflection direction H can be controlled in a desired direction around the vertical axis. In addition, the code|symbol 6A is a part to be cut out, and the code|symbol 6B is a scrap part.

The high frequency generator 46 applies a high frequency voltage to the nozzle 62 in order to generate a pilot arc between the electrode 60 and the nozzle 62 before starting plasma cutting.
While receiving the operation start signal SS from the nozzle 48, a high frequency voltage is applied to the nozzle 62 for 56 times.

The following programs and data are stored in the ROM 56 in advance.

(1) Various interpolation calculation programs that calculate the drive control amount of both servo motors 18 and 34 every minute time in order to move the torch 16 based on torch trajectory information (2) Torch obtained by the above interpolation calculation program Numerical control program that drives and controls both servo motors 18 and 34 based on the position information of 16 and the position information detected by encoders 20 and 36 (3) Included in the numerical control program, the part Control program for plasma arc deflection direction control to always form a 6A cut surface at right angles (4) Cutting current table, cutting speed table, and plasma arc deflection degree using material data and plate thickness data of workpiece 6 as parameters In other words, the composite magnetic field vector G
The magnetic field table in which the magnitude of M is set The plasma arc deflection direction control program includes the magnitude and direction of the magnetic field vector GMX - GMY generated by each magnetic field generator 17 and 19 from the magnitude and direction of the composite magnetic field vector GM. Contains a calculation program that calculates current value and current direction.

The cutting current table, cutting speed table, and magnetic field table are used to generate a stable plasma arc between the electrode 60 and the workpiece 6 so that the cut surface 7 of the part 6A of the workpiece 6 can be formed with high quality and at right angles. , data obtained experimentally or empirically using material data and plate thickness data as parameters are stored separately in advance.

The RAM 5B includes a torch position memory 66 that stores locus information of the torch 16 along the cutting path from the cutting start position to the cutting end position for each of a large number of cutting processes, and the position of the torch 16 during the cutting process, and the CPU 4B performs arithmetic processing. Various memories are provided to temporarily store the results.

Next, the drive control amount N including plasma arc deflection direction control is
The numerical control routine carried out in step 40 will now be explained with reference to the flowchart shown in FIG.

When the power is turned on to the plasma cutting device 1 and this control is started, initial settings are first executed (Sl), and the operation panel 4
4, the material and plate thickness are set by operating the character keys and numeric keypad, and the direction of the cutting path is set by using the forward cutting key and the reverse cutting key (S2). Next, cutting data is read out from the cutting current table, cutting speed table, and magnetic field table using the set material data and plate thickness data as parameters (S3), and is calculated based on the cutting current I included in this cutting data. The cutting current is set by adjusting the output regulator 64 using the adjusted adjustment signal AS, the cutting speed is set based on the cutting speed data ■, and the magnitude of the composite magnetic field GM is further set based on the magnetic field data ( S4). As a result, as shown in FIG.
0 is supplied with a cutting current.

Then, when the working gas is supplied from the gas supply device to the first and second torches 16 and the disconnection start switch on the operation panel 44 is operated (S5), both motors 18 and 34 are driven respectively based on the torch trajectory information in the ROM 56. The torch 16 is moved to the cutting start position (origin position), and the position data of the origin position of the torch 16 is stored in the torch position memory 66 (S6).
. For example, as shown in FIG. 7, the torch 16 is moved to the cutting start position Po, and the torch position memory 66 stores the position P.
The position data of , is stored.

Next, before starting plasma cutting, an operation start signal S
S is output to the high frequency generator 46 and the high frequency voltage is sent to the nozzle 6.
2, and a pilot arc is generated between the electrode 60 and the nozzle 62 (S7). Next, the output regulator 64 confirms that a pilot arc has occurred between the electrode 60 and the nozzle 62 (S8), and the drive of the high frequency generator 46 is stopped (S9). At this time, the gas ionized by this pilot arc becomes a plasma flow and reaches the workpiece 6, a main arc (plasma arc) is generated between the electrode 60 and the workpiece 6, and cutting of the workpiece 6 is started.

9 0 Next, the torch trajectory information regarding the cutting figure to be cut is read out, and the trajectory of the cutting route is calculated based on various interpolation programs. Based on this trajectory information, the current position of the torch 16 is The moving direction is approximately calculated as the direction connecting the current position and a remote point a predetermined minute distance ago (SlO), and both servo motors 18 and 34 are driven, and the position data of the torch 16 is updated. The current value is stored in the torch position memory 66 (Sll) and determined by the calculation program so that the direction of the composite magnetic field GM is the optimum direction based on the direction of movement of the torch 16, that is, the direction opposite to the direction of movement of the torch 16. and control the first magnetic field generator 17 and the second magnetic field generator 19 in the current direction (S12
). As a result, the deflection direction H is always rightward with respect to the movement direction, and the cut surface of the part 6A is formed at right angles. Then, when the cutting control continues (S13),
SIO to S13 are repeated, and this control ends when the cutting control ends. For example, as shown in FIG.
When the cut figure after the point is an arc, the torch movement locus related to the arc is read out, and the figure locus of this figure is calculated from the start position A, end position B, radius of the arc, center position, etc. included in this torch movement locus. When the current position of the torch 16 is the arc starting position A, the moving direction of the torch 16 at the position A is calculated from two points, the position A and the next separated point P1. Then, the first magnetic field generator 17 is configured so that the direction of the composite magnetic field GM is opposite to the direction of torch movement.
- The second magnetic field generators 19 are controlled respectively. As a result, when the torch 16 is in position A, the deflection direction H is directed to the right with respect to the direction of movement, and the cut surface 7 of the part 6A among the pair of cut surfaces extends from the top surface to the bottom surface of the part 6A. Approximately average
It is always formed at right angles. Therefore, no matter which point P1 (i-1, 2, 3...) the torch 16 moves to, the deflection direction H is always to the right with respect to the direction of movement of the torch 16, so the part 6A is cut. Surface 7 is always formed at right angles. Here, even if the cutting figure is a straight line other than a circular arc or a complicated curve, the first magnetic field generator 1
Since the 7 and 21 2 magnetic field generators 19 are each controlled, the direction of the composite magnetic field GM is opposite to the direction of torch movement, and the deflection direction H is always to the right in the direction of movement of torch 16.
Even when cutting these cut figures, the cut surface 7 is always formed at a right angle.

However, the tangential direction of the movement locus at each current position may be determined by calculation, and the tangential direction may be used as the moving direction of the torch 16.

The above description is based on the assumption that a constant plasma current is used both when cutting straight sections and when cutting curved sections. However, since the Lorentz force is proportional to the strength of the current and magnetic field, when cutting a curved section with a relatively large curvature, if the plasma current is corrected to decrease, the first and second Second magnetic field generator 17
・It is desirable to reduce the current supplied to 19 as well.

As explained above, a pair of magnetic field generators 17 and 19 are provided, and the direction of the composite magnetic field GM is controlled by controlling the first magnetic field generator 17 and the second magnetic field generator 19, respectively, to deflect the plasma arc. Since the direction H can always be directed to the right in the direction of movement of the torch 16, the cut surface 7 of the part 6A including corners and curves can always be formed at right angles. Furthermore, a rotating mechanism for rotating the magnetic field generator and the torch 16 can be eliminated, and the connection structure for connecting the working gas hose, cooling water hose, etc. to the torch can be simplified.

In addition, three or more sets of magnetic field generators that generate mutually crossing magnetic fields are provided, and the direction of one composite magnetic field obtained from the magnetic fields generated by these magnetic field generators is controlled according to the direction of movement of the torch 16. You can also do this.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a perspective view of a plasma cutting device, Fig. 2 is a partially enlarged front view showing a torch and a magnetic field generator, and Fig. 3 is a line taken along line ■-■ in Fig. 2. 4 is a block diagram of the control system of the plasma cutting device, FIG. 5 is an explanatory diagram illustrating the magnetic field hector and composite magnetic field vector from the first and second magnetic field generators, and FIG. 6 is a diagram of the plasma arc. A schematic flowchart of a numerical control routine including deflection direction 3 4 control;
FIG. 7 is an explanatory diagram illustrating the relationship among the moving direction of the torch, the direction of the composite magnetic field, and the deflection direction of the plasma arc at each cutting position of the torch. 1... Plasma cutting device, 6... Work, 6A... Parts, 7... Cutting surface, 16... Cutting torch, 17... First magnetic field generator,
17a・17b19a19b...excitation coil,
1B...Y direction servo motor, 19...Second magnetic field generator, 21, 23...Magnetic path forming member, 34...X direction servo motor, 40...Drive control device, 48...CPU
, 56...ROM, 58...RAM0

Claims (1)

[Claims] (1) A cutting torch that cuts a workpiece with a plasma arc ejected from a nozzle at its tip; a moving means that moves the cutting torch relative to the workpiece; It is equipped with a magnetic field generating means that acts on the arc, and a drive control means that numerically controls the moving means based on cutting processing information inputted in advance, and generates a plasma arc while moving a cutting torch relative to the workpiece. In a plasma cutting device that cuts a workpiece by deflecting the workpiece in a plane orthogonal to the magnetic field, a plurality of sets of magnetic field generating means for generating mutually intersecting magnetic fields are provided as the magnetic field generating means, and the cutting processing information is transmitted from the drive control means. and information regarding the position of the cutting torch, and controlling the plurality of sets of magnetic field generating means so that the deflection direction of the plasma arc is always in the optimum direction with respect to the direction of movement of the torch. A plasma cutting device featuring: