JPH0539834Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a plasma arc torch for processing a workpiece using a plasma arc.

<Prior art> Generally, in a plasma arc torch, a hollow tip with a narrow hole for ejecting plasma flow formed in the axial center of the tip, and an electrode covered by this tip are arranged at the tip of the torch. An arc is generated between the electrode and the chip or between the electrode and the workpiece, and the plasma arc squeezed by an appropriate plasma generation fluid such as nitrogen, hydrogen, or air supplied to the inside of the chip is used to generate the plasma of the chip. The flow is ejected from the jet hole toward the workpiece.

Conventionally, in this type of torch, as shown in FIG. 3, a processing electrode 11 and a conductive tip 13 are screwed onto first and second conductive members of a torch body 5 which are electrically insulated from each other. and an electrically insulating protective cup 1 that covers the chip 13 with a gap provided.
4' is arranged to supply working fluid to the space between the electrode 11 and the chip 13, and also to supply the working fluid to the space between the electrode 11 and the chip 13 and the chip 13 and the protective cup 1.
4', cooling fluid was supplied respectively.

<Problems to be Solved by the Present Invention> Incidentally, in the conventional torch described above, the range in which the processed portion can be observed, that is, the visible angle: θ1 is extremely small. Moreover, this visible range is biased toward the workpiece, so if you work while checking the machining part, you will have to be extremely hunched over, which will cause fatigue for the worker and cause machining work. was inefficient.

On the other hand, in order to obtain stable processing results, a guide member B is disposed along the line to be processed, and processing is performed while the tip of the torch is brought into contact with this guide member B.

In this case, it is convenient for the guide member B to be made of a metal material because it is easy to obtain and manufacture, but when the guide member B made of a conductive material is brought into contact with the chip 13, the guide member B and the chip 13 are During this process, a so-called double arc occurs, which adversely affects plasma arc machining and makes it impossible to obtain good machining results. For this reason, a guide member made of a conductive material provided with an appropriate insulating material is used.
Insulating materials are burnt out due to arc heat generated during plasma arc processing, and so-called dielectric breakdown progresses gradually due to adhesion of high-temperature molten metal. By the way, double arcs do not occur gradually, but occur suddenly after the insulation has been excessively broken down, so it is extremely difficult to determine whether or not the guide member can be used depending on the degree of breakdown of the guide member's insulation. It was hot.

Of course, if you frequently replace the guide member with a new one,
Although it is not necessary to pay attention to the presence or absence of dielectric breakdown, this naturally increases running costs and is not practical.

<Means for solving the problems> The plasma arc torch according to the present invention supports a processing electrode at the end of the shaft of the torch body, and uses a conductive torch having a narrow hole in the bottomed shaft. a tip electrically insulating and coaxially covering the electrode, supporting an electrically insulating protective cup at the end of the torch body on the tip side, and supplying a working gas between at least the electrode and the tip; In the plasma arc torch equipped with a working gas supply means, at least the tip of the tip protrudes toward the free end of the torch beyond the protective cup, and an electrically insulating member is disposed outside the tip except for the tip. It is characterized by forming an electrically insulating stepped portion for guiding the torch.

<Action of the present invention> At least the tip of the tip protrudes beyond the protective cup toward the free end of the torch, reducing the diameter of the tip of the torch, thereby expanding the visible range of the processed portion. Furthermore, an electrically insulating member is disposed on the outside of the tip except for the tip to form an electrically insulating step for guiding the torch. It can be made of a metal material that is easy to manufacture.

<Example> Hereinafter, the present invention will be explained in detail with reference to the illustrated example.

In FIG. 1, 1 is an electrode support member made of a conductive material, 2 is an electrically insulating member provided outside the electrode support member 1, and 3 is a chip receiver made of a conductive material provided outside the insulating member 2. The member 4 is an electrically insulating jacket provided outside the tip receiving member 3 except for the end in the _X1 direction, and the torch main body 5 is formed by the above members 1 to 4. Reference numeral 11 denotes a processing electrode having a high melting point insert 12 made of hafnium, zirconium, or an alloy thereof at its tip, and this electrode 11 is screwed onto the axial end of the electrode support member 1. Note that each end of the electrode 11 and the electrode support member 1 is positioned in the radial direction, that is, in the direction orthogonal to the X ₁ -X ₂ line, by a concave-convex engagement. Reference numeral 13 denotes a truncated cone-shaped conductive chip having a narrowed hole 131 in the bottomed shaft core, and a cylindrical part 13 is provided on the outside of the chip 13.
2,133 and a flange 134 are formed. Note that the cylindrical portion 132 of the tip 13 engages with the opening recess of the tip receiving member 3, and the torch body 5
radially positioned. Reference numeral 14 denotes an electrically insulating protective cup that is screwed onto the chip receiving member 3. In the illustrated case, when the protective cup 14 is screwed onto the chip receiving member 3, the flange 1 of the chip 13
The tip 13 is supported on the torch body 5 via a flanged electrically insulating member 16 that abuts the section 34. The cylindrical body 17 is an electrically insulating cylindrical body made of ceramics or a suitable heat-resistant resin. An annular space 63 is formed by the inner wall surface of the cylindrical body 17 and the outer peripheral surface of the electrode 11. A fluid path 61 connected to a working fluid supply means (not shown) is connected to a narrow hole 131 of the chip 13 via fluid paths 62 and 63.
is communicated with. Further, 71 is a cooling path connected to a cooling fluid supply means (not shown), and after passing through an annular space 72, the cooling path 71 is connected to a protective cup 1.
A plurality of fluid discharge paths 141 arranged around the periphery of 4
It communicates with the outside via.

In the above configuration, for example, plasma arc processing is performed while applying a voltage to the electrode 11 and the workpiece 15. That is, for example, if a voltage is applied between the electrode 11 and the workpiece 15 while supplying an appropriately selected fluid to the fluid path 61, the electrode 11 and the workpiece 1
5 is constricted by the working fluid supplied into the chip 13, and a jet of plasma arc is ejected from the constriction hole 131 of the chip 13. Cutting or welding is performed by this jet of plasma arc.

Of course, the torch body is cooled by supplying an appropriate fluid to the cooling path 71 at an appropriate time before or after the generation of the plasma arc.

Incidentally, since an electrically insulating step A is formed at the tip of the torch by an insulating member 16 and a protective cup 14, the step A is applied to a guide member B disposed along the line to be processed. It is possible to process the parts while they are in contact with each other. Of course, since the stepped portion is electrically insulating, even if the guide member B is made of a metal material,
There is no risk of double arc occurring as in the conventional case. Further, the frustoconical portion of the tip 13 protrudes beyond the protective cup 14 in the _X1 direction, and the diameter of the torch tip is reduced, so that the visible range of the processed portion; _θ2 is expanded. Therefore, when machining the electrically insulating stepped portion A on the tip side of the torch while contacting the guide member B, the machining portion can be easily checked without taking an unreasonable posture, and the machining process can be continued for a long time. This allows reliable machining work to be carried out.

It should be noted that an arc is generated between the electrode 11 and the chip 13 to create a plasma flow, or a so-called pilot arc is generated between the electrode 11 and the chip 13 to create a flow between the electrode 11 and the workpiece 15 during machining. A voltage can be applied to the FIG. 2 is a diagram showing another embodiment of the present invention, in which the chip 13
An electrically insulating member 16 is integrally disposed on the cylindrical portion 133 and the surface portion of the flange 134 in the _X1 direction by, for example, coating. In the illustrated case, the electrode 11 is screwed onto the axial end of the electrode support member 1. A screw 135 screwed onto the end of the tip 13 in the _X2 direction is screwed into a screw of the tip receiving member 3, and the flange 134 engages with the recess of the tip receiving member 3, so that the tip 13 is positioned in the radial direction. has been done. Further, a cylindrical body 17 similar to that shown in FIG. 1 is disposed inside the chip 13.
In the illustrated case, the protective cup 14 screwed onto the end of the torch main body 5 is formed in a cylindrical shape, and the protective cup 14 is arranged in the _X2 direction from the electrically insulating step A. .

It should be noted that when the tip 13 and the end of the torch body 5 are engaged in a convex-concave manner, the tip 13 is positioned in the radial direction, so that the tip 13 is supported at a desired position with respect to the torch body 5. That is, since the narrowed hole 131 of the tip 13 coincides with the axis of the torch body 5, a jet of plasma arc in a desired state can be obtained. Therefore, there is no risk of the conventional situation where the narrowed hole 131 of the tip 13 is misaligned with the axis of the torch, causing the plasma jet to bend and accelerate the wear of the electrode and tip.

Further, when the cylindrical body 16 is provided, the electrode 11 is consumed by use and the arc is automatically extinguished when the desired amount is used, so the torch body side will not be overheated and burnt out. In other words, in conventional torches in which the electrode and the tip are arranged concentrically without a cylindrical body, when the electrode wears out due to use and an arc occurs between the electrode and the tip, the torch Because the insulating material on the main body side will burn out,
Although it was necessary to replace the expensive torch body, by using the above-mentioned cylindrical body, it is only necessary to replenish the desired replacement parts.

As mentioned above, it is preferable to use a cooling fluid, to engage the tip and the end of the torch body in a convex-concave manner, or to provide an electrically insulating cylindrical body between the tip and the electrode. These can be omitted in the design.

When operating a plasma arc torch, the tip of the torch is often brought into contact with a workpiece or other member, but an electrically insulating member disposed outside the tip is placed on the tip of the tip as shown in the figure. Since this insulating member is not provided, the insulating member will not be damaged. Of course, an electrically insulating member arranged outside the chip can be arranged integrally with the protective cup. However, if we focus on the chip replacement cycle,
It is preferable that the insulating member provided outside the chip be formed separately from each component, as shown in FIG.

<Effects of the invention> In the plasma torch according to the invention, at least the tip of the tip protrudes toward the free end of the torch beyond the protective cup, and the diameter of the torch tip is reduced, so the visible range of the processed part is expanded. Ru. Moreover, since the electrically insulating stepped portion for guiding the torch is formed on the tip side of the torch, the guide member for abutting the torch can be made of a metal material that is easy to obtain and manufacture. Of course, when processing the insulating stepped portion on the torch tip side while contacting the guide member,
The visible range of the machining part is expanded compared to conventional torches, so you can easily check the machining part without taking an unreasonable posture, and you can perform reliable machining work over a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing an embodiment of the present invention;
The figure is a longitudinal sectional view showing another embodiment of the present invention, and FIG. 3 is a longitudinal sectional view showing a conventional example. 5... Torch body, 11... Electrode, 13... Chip, 14... Protective cup, 16... Electrical insulation member, A... Electrical insulation step.

Claims (1)

[Scope of utility model registration request] An electrode for processing is supported at the end of the shaft of the torch body, and the electrode is electrically insulated and coaxially covered with a conductive chip having a narrowed hole in the bottomed shaft, and the chip side A plasma arc torch comprising: an electrically insulating protective cup supported at the end of the torch body; and a working gas supply means for supplying working gas between at least the electrode and the chip; The tip protrudes further toward the free end of the torch than the protective cup, and an electrically insulating member is disposed outside the tip except for the tip to form an electrically insulating step for guiding the torch. A plasma arc torch.