JPH0519187Y2 - - 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. A plasma arc constricted by an appropriate plasma generating fluid such as nitrogen, hydrogen, or air supplied inside the chip is ejected from the plasma flow ejection hole of the chip toward the workpiece.

By the way, in this type of plasma arc torch, a high voltage is applied between the electrode and the workpiece during processing to maintain the plasma arc, so the tip and workpiece may come into contact or come very close together. In this case, a so-called double aure occurs through the chip. This double arc causes excessive chip wear. In addition, the high temperature generated during processing,
If so-called spatter adheres to the chip, the chip will burn out.

To deal with this, for example,
The one described in Publication No. 39872 has been proposed. That is, as shown in FIG. 6, an oxidized metal material that is difficult to wet with molten metal is sprayed onto the outer surface of the plasma cutting nozzle (=chip) 3' to a thickness of 0.2 to 1.0 mm.
An insulating heat-resistant layer 11 having a thickness of mm is formed.

<Problems to be Solved by the Present Invention> By the way, in the above-mentioned conventional technology, the thickness of the heat-resistant layer 11 must be made thin to 1 mm or less in order to prevent peeling, so insulation breakdown may occur due to insufficient insulation thickness. Not only is there a risk of a double arc occurring, but there is also the drawback that the thin heat-resistant layer 11 may be scraped due to unforeseen circumstances, making it unusable. Moreover, in this case, it must be replaced with a new one, but since the heat-resistant layer is formed on the outer surface of the plasma cutting nozzle by thermal spraying, the entire plasma cutting nozzle on which the heat-resistant layer is formed must be replaced. Therefore, there was a drawback that repair costs rose. Of course, since the thin heat-resistant layer 11 of the plasma cutting nozzle 3' must not be damaged, it is difficult to manage and handle a new plasma cutting nozzle for replacement.

<Means for solving the problem> 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 squeezed hole in the bottomed shaft. In a plasma arc torch, the plasma arc torch is provided with a working gas supply means for electrically insulatively and coaxially covering the electrode with a chip and supplying a working gas to at least a flow path between the electrode and the chip, the tip of the chip. An engaging portion with a different diameter is provided on the outer circumferential surface of the side, an axial through hole with a larger diameter than the squeeze hole of the tip is provided in the tip member made of ceramic, and an engaging portion with a different diameter is provided on the outer circumferential surface of the base side. The tip and the distal end member are integrally arranged by a thin annular member that engages with each of the engaging portions.

<Operation of the present invention> A thin annular member that engages with the respective engagement portions of the tip member and the tip made of ceramics,
Because the tip and tip member are integrated,
The tip member made of ceramics can be made thick.

Therefore, sufficient electrical insulation between the chip and the workpiece can be achieved. Further, since the tip member made of ceramics is formed separately from the tip, the tip member or the tip can be replaced. Furthermore, since the annular member that integrally engages the tip and the tip member is thin, it is easy to manufacture, and the tip member is not only easy to attach and detach, but also has a strong mechanical restraint against thermal changes. Therefore, there is no risk of damage to the tip member even if the torch tip is repeatedly brought to a high temperature and to room temperature due to repeated starting and stopping of plasma arc processing.

Of course, even if the torch tip is repeatedly brought to high temperature and then to room temperature, the tip, tip member, and annular member are engaged by the engaging portions of different diameters, so the tip member will not come off from the torch. .

Furthermore, since the diameter of the expansion hole in the tip member is larger than that of the tip, the tip member is not exposed to the jet of plasma arc ejected from the chip, and therefore, the temperature of the tip member becomes unnecessarily high. It can be used for a long life without any problems.

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

In FIGS. 1 and 2, reference numeral 1 denotes a processing electrode supported at the axial end of a torch body (not shown), and an insert 2 having a high melting point is provided at the tip. Reference numeral 3 denotes a conductive chip having a hole 301 in a bottomed shaft core, and covers the electrode 1 in an electrically insulative and coaxial manner as appropriate. On the outer circumferential surface of the tip 3, there is an engaging portion 302 with a different diameter, as shown in the figure.
A circumferential groove is provided. Reference numeral 4 denotes an electrically insulating tip member made of ceramics, and this tip member 4 is provided with an axial through hole 401 having a larger diameter than the squeeze hole 301 of the tip 3, and has a different diameter on the outer peripheral surface on the base side. In the illustrated case, the engaging portion 402 is provided with a flange. Reference numeral 5 designates a thin annular member whose both ends engage with the engaging portions 302 and 402 to integrally support the tip 3 and the distal end member 4. Note that 6 is a fluid path communicating with the expansion hole 301 of the chip 3, and this fluid path 6 is connected to a working gas supply means (not shown).

In the above configuration, for example, plasma arc processing is performed while applying a voltage to the electrode 1 and the workpiece 7. That is, for example, if a voltage is applied between the electrode 1 and the workpiece 7 while supplying an appropriately selected working gas to the fluid path 6, an arc generated between the electrode 1 and the workpiece 7 will cause the chip 3 to A jet stream of plasma arc is ejected from the squeezing hole 301 of the chip 3 by being squeezed by the working gas supplied inside. Cutting or welding is performed by this jet of plasma arc.

By the way, since an electrically insulating tip member 4 made of ceramics is disposed at the tip of the plasma arc torch, even if the tip of the torch comes into contact with the workpiece 7, there will be no contact between each part of the torch and the workpiece. No double arc will occur between the two. moreover,
Spatter generated during processing does not adhere to the surface of the tip member 4. Furthermore, since the tip member 4 can be formed thick, the insulation distance H between the torch and the workpiece 7 can be set appropriately. In addition, when the annular member 5 is formed of a metal material, such as copper, aluminum, or an appropriate alloy thereof, the distance Ho between the annular member 5 and the end surface of the tip member 4 may be understood as an insulation distance. Further, when the annular member 5 is formed of a non-metallic material, for example, a suitable heat-resistant resin, the end face of the chip 3 serves as a reference for the insulation interval.

Of course, when the annular member 5 is formed of a heat-resistant resin and a metal member for tightening, the distance at the tip end of the metal member that is electrically connected to the chip 3 is used as the reference for the insulation interval.

Also, during processing, the squeeze hole 301 of the chip 3
A jet of plasma arc is ejected from the tip, but since the diameter of the opening hole 401 of the tip member 4 is larger than that of the opening hole 301 of the tip, the tip member 4 is not exposed to the jet of plasma arc. , the tip member 4 can be used for a long life without becoming unnecessarily high in temperature.

Of course, since the tip member 4 can be formed thick, plasma processing can be performed without any problem even if a part of the tip member 4 is chipped due to an unexpected situation.

By the way, if the tip 3 or the tip member 4 becomes unusable during the processing operation, the tip 3,
By disengaging the distal end member 4 and the annular member 5, the tip 3 or the distal end member 4 can be replaced with a new one. In this case, after appropriately performing plasma processing, the annular member 5 cannot be reused because it has become brittle due to thermal effects.
Therefore, a new annular member 5 is used. Since this annular member 5 is a thin unit, it is easy to manufacture and easy to handle. Of course, if plasma processing is hardly performed, the annular member can be reused.

Note that it is conceivable to form a recess at the tip of the tip and swage the thin wall of the recess with the tip member inserted into the recess to integrally form the tip and the tip member. The caulked portion becomes brittle due to thermal effects during plasma processing, so once the caulked portion is loosened, it will almost always separate from the chip. Therefore, the process of forming a recess at the tip of the tip is troublesome and expensive, and the tip or the tip member cannot be replaced.

FIG. 2 is an enlarged view of the thin-walled annular member 5, showing a preferred example in which it is made of copper, aluminum, or an alloy thereof. This thin annular member 5 has a stepped portion 501 formed in advance at one end of the cylinder by drawing, bending, or the like. For example, with the stepped portion 501 in contact with the engaging portion 401 of the tip member 4, the other end of the cylinder is bent inward, and the annular member 5 is attached to the engaging portion 301 of the tip 3.
2. In this case, the bent end of the annular member 5 can be bent along the entire circumference when the different diameter engaging portion 302 of the chip 3 is a circumferential groove; Only one or more appropriate locations on the groove may be bent.

FIG. 3A and FIG. 3B are views showing modified examples of the annular member 5, respectively, and the one shown in FIG. 4 radial recesses 501, 501,...
After inserting this annular member 5 into the tip of the torch, the other end of the cylinder is bent as appropriate.
Furthermore, the one shown in FIG. 3B has, for example, four radial recesses 501, 501, . axial slit 50
2 are provided. The radial recesses 501, 501, .
and engages with the engaging portions 302, 402 of the tip member 4. If the slit 502 is located on the tip 3 side, the metal tip 3 and the annular member 5 can be easily engaged and disengaged by the spring action of the slit. Of course, the above slit 502
can be provided on both ends of the annular member 5 and used for engaging and disengaging the annular member 5, the tip member 4, and the tip 3.

Furthermore, the annular member 5 can be easily handled by providing a slit 502 that opens at both ends of the annular member 5 and radial recesses 501, 501 at both ends of the annular member 5. Of course, it is preferable to provide this recess 501 in advance, but it can also be formed at an appropriate time.

FIG. 4 is a diagram showing another embodiment of the present invention, in which engaging portions 302 and 401 of different diameters provided on the tip 3 and the tip member 4 are formed in a conical shape. In this case, as the thin annular member 5, an appropriate heat-resistant resin member can be used. For example, it is preferable to use a glass tape containing Si or a heat-shrinkable tape or tube made of Teflon (trademark), silicone rubber, etc., since the tip and tip member 4 can be easily engaged. It can be an annular member as shown in Figure A or Figure 3B.

As shown in FIG. 4, if the engaging portions of the tip member 4 of different diameters are formed into a conical shape, the shape of the tip member 4 made of ceramics becomes gentle as a whole, so that it is easy to cause problems at the corners. A sudden cracking phenomenon can be avoided.

FIG. 5 is a diagram showing still another embodiment of the present invention, in which the tip 3 and the tip member 4 are brought into contact with each other, and the spring force due to the axial slit 502 of the annular member 5 and the tip 3 and the tip member 4 are brought into contact with each other. The distal end member 4
is supported for chip 3.

Note that a slit 50 is formed on the tip 3 side of the annular member 5.
Although it is preferable to provide the tip 2 and lock it by spring force, it goes without saying that the end on the tip 3 side may be bent or squeezed.

Further, the annular member 5 can be formed into a thin-walled cylinder or a cylindrical shape divided in the axial direction, but as shown in FIGS. If ... is provided in advance, the bending work of the annular member 5 on the tip member 4 side, which is relatively fragile, will be unnecessary during installation.
The operation of integrating the tip 3 and the distal end member 4 using the annular member 5 can be easily performed. Further, the annular member 5 is made of a metal member and a non-metal member, and the non-metal member is included like a cushion so that the tip 3 and the distal end member 4 can be integrally engaged. Furthermore, the engaging portions of different diameters provided on the tip 3 and the tip member 4 can be one or more recesses, protrusions, or notches provided outside the circumference.

<Effects of the Invention> In the plasma arc torch according to the present invention, since the tip member made of ceramics is provided separately from the tip, the tip member can be appropriately thickened. Therefore, sufficient electrical insulation between the conductive chip and the workpiece can be achieved. Further, since the tip, the tip member, and the annular member are engaged by the engaging portions having different diameters, the tip member will not come off from the torch even if the torch tip is repeatedly heated to a high temperature and returned to normal temperature. Furthermore, since the annular member 5 is a thin unit, it is easy to manufacture and easy to handle. Moreover, since the annular member that integrally engages the tip and the tip member is thin, its mechanical restraint against thermal changes is not strong, and therefore even if the torch tip is repeatedly heated to high temperature and then to normal temperature. , there is no risk of the tip member being damaged. Of course,
If it is possible to freely replace the separate tip or tip member, and when replacing it,
Since the annular member is thin, the work can be easily performed.

Furthermore, since the tip member made of ceramics can be made thick, even if a part of the tip member is chipped, it will not interfere with use.
For this reason, not only does the replacement cycle of the tip member become longer, but also the workability is improved because it is not necessary to take much care in handling the tip member for replacement.

In addition, since the diameter of the expansion hole in the tip member is larger than that of the tip, the tip member is not exposed to the jet of plasma arc ejected from the chip, and therefore the tip member is not heated unnecessarily. It can be used for a long life without any damage.

Note that the thick tip member allows the insulation distance between the torch and the workpiece to be maintained at a distance that does not cause double arcs, so the torch tip can be kept in contact with the workpiece, in other words, the plasma arc can be maintained in a steady state. It can be processed while

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing an embodiment of the present invention;
The figure is an enlarged view of the main parts of FIG. 1, FIGS. 3A and 3B are views showing modifications of the parts shown in FIG. 2, and FIGS. 4 and 5 are views of the parts shown in FIG. FIG. 6 is a half-sectional front view showing another embodiment, and FIG. 6 is a longitudinal sectional view showing a conventional example. 1... Electrode, 3... Conductive chip, 4... Tip member, 5... Annular member.

Claims (1)

[Scope of utility model registration request] An electrode for processing is supported at the axial end of the torch body, and the electrode is electrically insulated and coaxially covered with a conductive chip having a narrowed hole penetrating the bottomed axial core to the outside. , in a plasma arc torch equipped with a working gas supply means for supplying working gas to at least a flow path between the electrode and the tip, an engaging portion having different diameters is provided on the outer peripheral surface of the tip end side of the tip; A tip member made of ceramics is provided with an axial through hole having a larger diameter than the narrowed hole of the tip, and an engaging portion with a different diameter is provided on the outer circumferential surface of the base side,
A plasma arc torch in which the tip and the tip member are integrally arranged by a thin annular member that engages with each of the engaging portions.