JPH0331508Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to an improvement of an air-cooled plasma torch with enhanced cooling effect.

"Prior art and its problems" Recently, many air-cooled plasma torches have been commercially available in place of conventional water-cooled plasma torches due to ease of handling. As shown in the figure, there is nozzle 1 at the tip.
A torch body 2 provided with a torch is arranged concentrically at a predetermined distance around an electrode 3 arranged on the axis on the back side of the nozzle 1, and a torch body 2 is provided concentrically with the axis near the outer periphery of the torch body 2. A large number of cooling air vents 21 are bored, and after guiding the air introduced into the electrode 3 from the base side of the torch into the through holes 21, the air is formed on the outer circumferential side of the nozzle 1 while passing through the through holes 21. spout 4
The structure is configured such that the air can be drawn out to the outside, and the electrode 3 nozzle 1, the torch body 2, etc. arranged around it are cooled by the passage of the air.

``Problem that the invention aims to solve'' However, due to the characteristics of the air itself, the heat removal effect of such an air-cooled torch is significantly lower than that of a conventional water-cooled torch, and the air is injected from the center of the nozzle 1. The cooling air is drawn out around the working gas to form a plasma arc column, so if you try to increase the cooling effect by increasing the amount of cooling air, the cooling air will get caught up in the working gas, making it difficult to cut well. This creates the problem of becoming.

Therefore, in the air-cooled torch with the above configuration, 10
It is difficult to use the torch continuously for more than 20 minutes, and even if it is used intermittently for about 10 minutes, the heating temperature on the side of the torch body 2 will exceed 300℃. It is not possible to use a resin molded body for the enveloping body that covers the surroundings and holds them together, and various parts such as insulators disposed inside the torch must also be made of highly heat resistant materials. This inevitably leads to complicated assembly work and increased production costs.

In view of the drawbacks of the prior art, the present invention has been developed to significantly improve the cooling effect without increasing the cooling air flow, and to maintain the temperature at which the resin molded body etc. will not deteriorate even after long-term use. The purpose is to provide a type plasma torch.

"Means for Solving Problems" In order to achieve this technical problem, the present invention aims to provide a torch body 2 with a nozzle 1 mounted on the tip side, which is bored along the axial direction, and a hole is formed along the axial direction, and the nozzle 1 is attached to the torch body 2. A plurality of air vents 21 having an outlet end nearby are provided; an air chamber 6 is formed between the inner circumferential surface of the cap 5 at the outlet end of the vent hole 21 and the outer circumferential surface of the torch body 2; On the outer peripheral surface of the torch body 2,
We propose an air-cooled plasma torch having the following essential features: fin means 22 with which the air flow led out from the outlet end of the through hole 21 can collide.

The fin means 22 may be provided parallel to the axis or inclined with respect to the axis as long as the airflow can collide with the fin means 22, but the fin means 22 may be provided along the surface facing the outlet end of the through hole 21. By configuring it as a plurality of annular fins 22, the effects described later can be achieved more smoothly.

Further, by forming a large number of through holes 22a in the annular fin 22 along the axial direction of the through hole 21, the contact area of the air flow toward the torch body 2 side is increased, and the stirring effect described later is further enhanced.

"Function" According to this technical means, the torch main body 2 is cooled while cooling air passes through the through hole 21, and the air is directed to the torch tip side where the heating temperature is highest due to heat transfer from the plasma arc column. A chamber 6 is provided to cool the air passing through the through hole 21 by adiabatic expansion of the air flow, and the cooled air collides with the fin means 22 and is stirred within the air chamber 6. Since the air chamber 6 is configured to be discharged to the outside through the jet port 4 and the small holes 41 on the outlet side, the cooling effect is much higher than that of conventional air-cooled torches even when using an air flow with a small heat capacity. ,
Even if continuous cutting is performed for 20 minutes or more using the torch, the heating temperature on the torch body 2 side will not rise above 200°C.

"Effect of the invention" Therefore, according to this invention, since the heating temperature on the torch body 2 side does not rise above 200°C, continuous cutting for a long time is possible, and the torch body 2 and its surroundings are Thermal deterioration of the various installed parts is significantly reduced, and durability can be improved.

Further, a resin molded body 7 or the like can be used as a covering body that covers the outer periphery of the torch main body 2 and holds them together, and various types of insulators etc. disposed inside the torch can be used. There is no need to use particularly heat-resistant parts, which inevitably leads to easier assembly and lower manufacturing costs.

It has various effects such as

Embodiments Hereinafter, preferred embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this example are as follows, unless otherwise specified.
This is not intended to limit the scope of this invention, but is merely an illustrative example.

FIG. 1 is a half-cut sectional view of an embodiment of the present invention;
FIG. 2 is a cross-sectional view showing only the upper part of the center line of the part offset by 90 degrees with respect to FIG.

11 is an internal body with an electrode 3 attached to its tip; 2
is a torch body surrounded by the outer periphery of the inner body 11, and a cooling air introduction pipe 8 and a working gas (O ₂ ) introduction pipe 9 are connected to the base side thereof in parallel along the axis.

Reference numeral 10 denotes a resin molded body that integrally grips and covers both the main bodies 2, 11 and the introduction tubes 9, 8, and 5 denotes a cap screwed onto the outer periphery of the torch body 2 exposed on the tip side of the molded body 10. , 1 is a nozzle screwed onto the inner periphery of the tip of the torch body 2.

Next, the configuration of each of these parts will be explained in detail.

The internal body 11 is made of a conductive material, and is configured such that a negative voltage is applied to the electrode 3 attached to the tip side of the internal body 11 from a power terminal for plasma arc generation connected to the cooling air introduction pipe 8 side. There is.

The inner body 11 is arranged along the axis of the electrode 3.
A center hole 16 is drilled that reaches the back side, and a conduit 81 of the introduction pipe 8 is extended into the center hole 16, so that the cooling air guided from the introduction pipe 8 directly collides with the back side of the electrode 3. Configure it like this. The collided airflow then flows backward through the outer circumferential side of the pipe 81 and backs up into the inner body 11
It is guided into the through hole 21 on the torch body 2 side from the guiding hole 12 bored on the base side.

Further, a spiral groove 14 is formed on the outer peripheral surface of the inner body 11 facing the insulator 2b of the torch body 2 via the cylindrical cavity 13, and the spiral groove 14 allows the working gas introduction pipe 9 to be connected to the cylindrical cavity 13. The working gas introduced therein is diverted into a spiral flow.

The torch body 2 consists of two electrically conductive divided bodies 2a, 2 that are integrally attached with an insulator 2b in between.
A positive power terminal cable 23 is connected to the lower divided body 2a, and a positive voltage for pilot arc generation is applied to the nozzle 1 attached to the tip side of the lower divided body 2a. The diameter of the front side of the side divided body 2a is reduced in a step-like manner, and an air chamber 6 is formed on the outer circumferential surface of the reduced diameter divided body 2a and the inner circumferential surface of the cap 5.

A through hole 2, which will be described later, is located within the air chamber 6.
1. A plurality of annular fins 22 on the surface facing the exit end.
, and a large number of through holes 22 a are bored in the annular fin 22 along the axial direction of the through hole 21 .

On the other hand, the two divided bodies of the torch main body 2 and the insulator 2b
A ring-shaped air pool 24 is formed therebetween, and a through hole 21 extending from a stepped portion facing the annular fin 22 to the guide hole 12 is formed concentrically along the axial direction so as to pass through the air pool. A large number of holes are drilled in the shape of a hole.

The nozzle 1 has a center hole 14 through which the swirling flow of the working gas is ejected, and a ring-shaped jet port 4 is formed on the outer circumferential surface of the nozzle 1 facing the cap center opening 51. A large number of knurled grooves 15 are carved on the top, and the spout 4
This limits the amount of emitted airflow.

Also, on the side of the cap 5, the center opening 51
A large number of small holes 52 are bored in the circumferential direction on the sloped surface on the upstream side and the downstream side of the annular fin 22, and the amount of air flow led out from the small holes 52 is determined by The amount is set to be considerably larger than the amount ejected.

Next, the operation based on this embodiment will be explained.

First, the working gas is introduced from the working gas introduction pipe 9, and after being turned into a spiral flow by the spiral groove 14 formed in the cylindrical gap 13 between the torch body 2 and the internal body 11, the spiral flow is passed through the nozzle. In this state, a working voltage is applied between the electrode 3 and the workpiece plate, and a high frequency voltage is applied between the nozzle 1 and the electrode 3 for a predetermined period of time. A pilot arc is generated in between, and then a plasma arc column is generated toward the workpiece plate. (The pilot arc is reduced when the high frequency voltage applied between the nozzle 1 and the electrode 3 is cut off.) At the same time, the internal body 1 is
The cooling air introduced into 1 passes through the pipe 81 and first collides with the electrode 3, and after cooling the electrode 3,
It enters into the through hole 21 from the outer periphery of the conduit 81 through the guide hole 12, and is injected into the air chamber 6 while cooling the torch body 2.

Then, the air flow expands adiabatically within the air chamber 6 to cool the air that has passed through the through hole 21, and the cooled air flow collides with the annular fin 22 and is stirred within the air chamber 6. While cooling the torch main body 2 and nozzle 1, a part of it is guided into the through hole 22a to further cool the torch main body 2 and nozzle 1, while cooling the nozzle 4 and the small hole on the outlet side of the air chamber 6. 51 to the outside.

According to such an embodiment, the effects of the previous invention can be smoothly achieved, and according to experiments conducted by the present inventor, the temperature increase of the torch body 2 under the same cutting conditions and the same amount of cooling air is reduced. When not attaching fins
The effect of adding the fins was noticeable, as the temperature was 339℃, and 169℃ with the fins attached, and we were able to significantly increase the usage rate of the plasma torch.

[Brief explanation of the drawing]

FIG. 1 is a half-cut sectional view of an embodiment of the present invention;
FIG. 2 is a sectional view showing only the upper part of the center line of the part offset by 90 degrees from FIG. 1. 1... Nozzle, 2... Torch body, 21... Air vent, 5... Cap, 6... Air chamber, 22...
…fin means.

Claims (1)

[Claims for Utility Model Registration] 1. A plurality of air holes that are bored along the axial direction in the torch body, which is equipped with a nozzle on the tip side that spouts working gas from a central hole, and that have an outlet end near the nozzle attachment position. In addition to providing a through hole, a fin is provided on the outer circumferential surface of the torch body within the air chamber formed between the inner circumferential surface of the cap at the outlet end of the through hole and the outer circumferential surface of the torch body, with which the air flow led out from the outlet end of the through hole can collide. An air-cooled plasma torch characterized by the provision of a means. 2. The air-cooled plasma torch according to claim 1, wherein the fin means is one or more annular fins provided along a surface facing the outlet end of the through hole. 3. The air-cooled plasma torch according to claim 2, wherein the annular fin is provided with a large number of through holes along the axial direction of the through hole.