JPH02217173A - Plasma arc cutting machine - Google Patents

Abstract

PURPOSE:To carry out plasma arc cutting with high accuracy by forming the plasma gas jet of a nozzle of a plasma torch for piercing larger than that for cutting. CONSTITUTION:At least one piece of plasma torches 1a and 1b for which a piercing torch is different from cutting torch are used for a plasma arc cutting machine. The plasma gas jet of the nozzle 11 of the plasma torch 1a for piercing is then formed larger than that for cutting. An operating current to act on the plasma torch 1a for piercing is made higher than that for cutting. A nozzle for a shielding gas curtain is provided around the nozzle of the plasma torch for piercing. The plasma torch for piercing and that for cutting are arranged for air cooling type and water cooling type, respectively. By this method, piercing work is smoothly carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma arc cutting machine that cuts a plate material using a plurality of plasma torches.

[Conventional technology]

In plasma arc cutting, a drilling start is often used to start cutting by drilling a hole in the material to be cut (piercing). At this time, the molten material to be cut is blown upward until a hole is made in the material, but this blown material often adheres to the nozzle of the plasma torch, which is the outlet for the plasma gas, and Damage the nozzle and cause deterioration of cutting quality.

Since the molten particles to be cut adhere to the nozzle only during drilling and not during cutting, two types of plasma torches, one for drilling and one for cutting, are attached to one moving device. It has been known for some time that the cutting operation is carried out using a plasma torch exclusively used for cutting, which avoids damage during drilling.

[Problem to be solved by the invention]

The drilling and cutting operations in normal plasma arc cutting operations are significantly more severe than the drilling and cutting operations.

However, in the conventional plasma arc cutting machine, the same plasma torch is used for both drilling and cutting.

For this reason, first of all, when using a plasma torch with a small capacity when drilling a hole, it is difficult for the material to be cut to blow up and be blown away by the plasma torch, resulting in a large bulge around the hole, and when the plasma torch for cutting passes near this bulge, Contact may have caused damage to the nozzle.

In addition, drilling with a plasma torch with low capacity takes a long time to drill and is a difficult task.
It also causes damage faster. If a hole is drilled using a plasma drilling torch that has been damaged, the bulge that adheres to the material to be cut will increase, and the plasma cutting torch will often be damaged.

These problems are due to the fact that drilling requires a plasma torch with a large capacity. On the other hand, the capacity of the plasma torch required for cutting may be smaller than the capacity required for drilling, and conversely, if the capacity is large, it is necessary to cut at high speed in order to make quality cuts. However, if the moving device is moved at high speed, it is difficult to achieve high precision of the moving device, and accurate shape cutting becomes impossible.

The present invention has been made in consideration of the above-mentioned problems, and by changing the performance of the plasma torch for drilling and cutting, and increasing the performance of the plasma torch for drilling compared to cutting, it is possible to use a plasma torch for drilling. The purpose is to reduce the bulge formed by the blown-up material adhering to the material to be cut, and to shorten the lifespan of the plasma torch for drilling to the same level as that for cutting. Furthermore, a cleaning tool is attached to the holder that supports the plasma torch to remove bulges that adhere to the material to be cut during drilling.

The object of the present invention is to provide a plasma arc cutting machine in which the cutting plasma torch is not damaged and can continue cutting with high precision.

[Means to solve the problem]

In order to achieve the above object, a plasma arc cutting machine according to the present invention is a plasma arc cutting machine that uses different plasma torches for drilling and cutting, and in which the plasma gas spout of the nozzle of the plasma torch for drilling is cut. It has a larger diameter than the one for use.

Furthermore, in both of the above plasma torches, the magnitude of the operating current acting on the plasma torch for drilling was made larger than that for cutting.

Of the two plasma torches mentioned above, a nozzle for a shielding gas curtain was provided around the nozzle of the plasma torch for drilling.

Of the two plasma torches mentioned above, an air-cooled type was used for drilling, and a water-cooled type was used for cutting.

The height of the tips of both plasma torches relative to the material to be cut was set higher for the plasma torch used for drilling.

A cleaning tool for cleaning the upper surface of the material to be cut after drilling was provided on the torch holder that supports the plasma torch.

[For production]

By making the nozzle diameter of the plasma torch for drilling larger than the nozzle diameter of the plasma torch for cutting, it is possible to increase the flow rate of plasma gas ejection, increasing the momentum of the plasma gas, and reducing the blow-up during drilling. The ability to blow away the melt without adhering to the material to be cut is increased, and the amount of molten material adhering to the material to be cut can be reduced.

Further, by making the operating current of the plasma torch for drilling larger than the operating current of the plasma torch for cutting, the drilling ability is increased and the amount of melt adhering to the material to be cut is reduced.

In addition, a nozzle for a shielding gas curtain is installed around the plasma torch used for drilling holes to prevent surrounding air from getting caught up in the plasma gas, to prevent the purity of the plasma gas from decreasing, and to prevent the shielding gas from blowing out. The ability to blow away the molten material that has blown up due to the action is increased, increasing the drilling ability and reducing adhesion to the material to be cut.

To remove any build-up that has adhered to the material to be cut, attach a cleaning tool to the holder that supports the plasma torch, scrape off the adhered material, and then perform the cutting operation with the cutting plasma torch. Prevent contact with cutting plasma torch.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

In Fig. 1, 1a is a plasma torch for drilling, 1
b is a plasma torch for cutting, which is connected together with the material to be cut 2 to a power source 4 controlled by an NC controller 3.

Figures 2 and 3 show the overall configuration of a plasma arc cut material, with reference numeral 5 being a table that supports the material to be cut 2, and 6 being a movable frame that is supported movably in the Y direction with respect to the table 5. , 7 is a feed screw for moving this moving frame 6, 8
A torch holder is supported by a moving frame 6 so as to be movable in the X direction, and both plasma torches 1a and 1b are attached to this torch holder 8. The moving frame 6 and the torch holder 8 are each moved in respective directions by the NC controller 3.

That is, the NC controller 3 first cuts the material 2 to be cut.
The plasma torch 1a for drilling is positioned at the cutting start position, and then a drilling command is sent to the power source 4. Upon receiving the drilling command, the power source 4 operates the plasma torch 1a for drilling to perform the drilling work.

After completing the drilling work, the NC controller 3 positions the plasma torch 1b for cutting at the location where the hole was drilled.
Sends a disconnection start instruction to the power source 4. The power source 4 that receives the command to start cutting operates the plasma torch 1b for cutting, generates a plasma arc thereto, and starts cutting. When cutting starts, the plasma torch 1b for cutting is moved along a desired cutting line according to a command from the NC controller 3.

There are two types of plasma torches 1a and 1b: a water-cooled type and an air-cooled type.

FIG. 4 shows an air-cooled plasma torch, in which cooling water flows in through a cooling water inlet 9, cools an electrode 10, a nozzle 11, and a torch body 12, and then flows out through a cooling water outlet 13. As is well known, the drilling and cutting operations are performed by directing the plasma gas flowing in from the gas inlet 14 to the nozzle 1.
This is performed by forming an arc discharge between the electrode 10 and the material to be cut 2 while the plasma gas is ejected from one plasma gas ejection port 11a.

Fig. 5 shows an air-cooled plasma torch, in which the cooling air flowing in from the cooling air flow port 15 flows through the electrode 10' and the nozzle 1.
1' and the torch body 12', the nozzle 11'
and the nozzle cover 16, and is discharged toward the tip of the nozzle 11'.

In this embodiment, an example is shown in which plasma gas is used as the cooling air, and the cooling passage for the cooling air is branched to guide the plasma gas to the plasma gas outlet 118'.

FIG. 6 shows the plasma torch shown in FIG. 4 in which an oxygen gas curtain is ejected around the nozzle 11. An oxygen gas curtain cover 18 is attached to the outside of the nozzle cover 17, and this enzyme gas Curtain cover 18
The tip of the nozzle 11 is opened toward the tip side of the nozzle 11, and an oxygen gas supply port 18 is provided at the inner base of the nozzle 11.

The plasma torch configured as described above is used for drilling and cutting, respectively. At this time, the drilling and cutting are performed by the plasma gas jet of the nozzle 11 in the water-cooled plasma torch shown in FIG. The diameter of the outlet 11a is changed so that the diameter of the plasma torch 1a for drilling is larger than that for cutting.

Further, in the water-cooled plasma torch shown in FIG. 4, the operating current applied to the plasma torch 1a for drilling and the operating current applied to the plasma torch 1b for cutting are changed. At this time, when the operating current of the plasma torch 1a for drilling is aA1 and the operating current of the plasma torch 1b for cutting is bA, a>b is satisfied.

The following method may be used to set the operating currents of the plasma torches 1a and 1b. , NC controller 3
When drilling a hole, the power source 4 sends a drilling command and a command to set an operating current value to the power source 4, and the power source 4 that receives these commands performs the drilling work at the set current value. When cutting, the NC controller 3 sends a command to the power supply 4 to start cutting and a command to set an operating current value different from that used during drilling work, and the power supply 4 that receives this command outputs the current of the set current value. It is supplied to the plasma torch 1b for cutting.

Another way to set the current value is to set the current value for drilling work and the current value for cutting work in the power supply 4 in advance, and then just send the drilling command and cutting start command from the NC control 3. You can also.

In the above embodiment, each plasma torch la.

An air-cooled type shown in FIG. 5 may be used for 1b.

Further, an air-cooled type may be used for drilling, and a water-cooled type may be used for cutting.

The oxygen gas curtain type platen torch shown in FIG. 6 is used as a plasma torch 1a for drilling. In this case, the drilling portion is shielded with oxygen gas.

FIG. 7 shows another embodiment of the present invention, in which when a plasma torch 1a for drilling and a plasma torch 1b for cutting are attached to a torch holder, the height of the tips of both torches 1a and 1b from the workpiece 2 is When Sa is Ha and Hb, Ha>
It was set as Hb.

The height Ha of the plasma torch 1a for drilling is adjusted to a height at which blown-up particles are difficult to adhere to, and the height Hb of the plasma torch 1b for cutting is adjusted to a height that allows high-quality cutting.

FIG. 8 shows another embodiment of the present invention, in which brushes and the like facing the workpiece 2 are cleaned between the plasma torches 1a and 1b for drilling and cutting, which are attached to a torch holder 8. A tool 19 is attached to the torch holder 8.

When a hole is made with the plasma torch 1a for drilling, debris from the melted material to be cut adheres to the periphery of the hole, but while the plasma torch 1b for cutting moves to this hole, the cleaning tool 19 is removed. Clean the entrance of the hole by gently scraping away any debris from the material to be cut that has adhered to this area.

〔Effect of the invention〕

According to the present invention, in both the plasma torches 1a and 1b for drilling and cutting, the diameter of the plasma gas outlet of the nozzle for drilling is made larger than that for cutting. By setting the magnitude of the operating current that acts on the plasma torch 1a to be larger than that for cutting, or by providing the plasma torch 1a for drilling with a nozzle for a shield gas curtain, drilling work can be performed with a larger diameter than cutting work. The drilling process is performed using a plasma arc ejected from a plasma gas outlet, a large current, or a shielding gas. This can be done with less damage to the nozzle and less damage to the nozzle. The molten material adhering to the periphery of the hole can be removed by attaching a cleaning tool to the holder that supports the plasma torch.

Therefore, in the subsequent cutting operation using the plasma torch 1b for cutting, accurate cutting can be performed.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a schematic overall explanatory diagram, FIG. 2 is a front view of a plasma arc cutting machine,
FIG. 3 is a partially cutaway side view, FIGS. 4, 5, and 6 are sectional views showing different embodiments of the main parts of the plasma torch, FIG. 7 is an explanatory diagram of the arrangement of the plasma torch, and FIG. The figure is an explanatory diagram showing an example in which a cleaning tool is attached. 1a and 1b are plasma torches, 2 is a machine to be cut, 8 is a torch holder, 11, 11. ' is a nozzle, 11a,
11 a' is a plasma gas outlet, and 19 is a cleaning tool.

Claims (6)

[Claims] (1) Different plasma torches 1a for drilling and cutting
, 1b, the plasma arc cutting machine is characterized in that the plasma gas jet ports of the nozzles 11, 11' of the plasma torch 1a for drilling are made larger in diameter than those for cutting. Machine. (2) Different plasma torches 1a for drilling and cutting
, 1b, wherein the operating current acting on the plasma torch 1a for drilling is made larger than that for cutting. (3) Different plasma torches 1a for drilling and cutting
, 1b, characterized in that a shielding gas curtain nozzle is provided around the nozzles 11, 11' of the plasma torch 1a for drilling. (4) The plasma arc cutting machine according to claim 1, wherein of the plasma torches 1a and 1b, the plasma torch 1a for drilling is air-cooled, and the plasma torch 1b for cutting is water-cooled. (5) The plasma arc cutting machine according to any one of claims 1, 2 and 3, characterized in that the height of the tips of both plasma torches (1a, 1b) relative to the material to be cut is set higher for the plasma torch (1a) for drilling. (6) Different plasma torches 1a for drilling and cutting
, 1b, the plasma arc cutting machine is characterized in that the torch holder 8 supporting the plasma torches 1a, 1b is provided with a cleaning tool 19 for cleaning the upper surface of the workpiece 2 after drilling. Plasma arc cutting machine.