JPH0117052B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applied to welding and cutting torches in which preheated oxygen and fuel gas are mixed inside the torch. This invention relates to a gas welding and cutting torch that makes it possible to prevent this.

<Prior art> As shown in FIG. 5, a conventional torch internal mixing type torch sucks fuel gas by flowing high-velocity oxygen from the injector hole 12a of the injector head 14 and introduces it into the mixed gas passage 17. It was configured.

<Problems to be Solved by the Invention> However, in the above-mentioned conventional torch, if the tip of the nozzle 19 comes into contact with a steel plate or is blocked by a spatter or the like in the ignited state, the flame will flow from the nozzle 19 to the head of the torch. 18, mixed gas passage enlarged part 1 through mixing pipe 15
There were drawbacks such as the backflow and continued combustion up to around 7a, which easily caused the base of the mixing tube to melt.

In order to prevent this flashback, for example, a preheating oxygen injector is used to provide a suction effect, or as shown in Japanese Patent Application No. 58-224213, the dimensions of each part of the gas mixing section are configured at a certain ratio. had been proposed.

However, the former method does not take into account the continuous flashback caused by continuous combustion in the gas mixing section, and the latter has drawbacks such as its ability to prevent continuous flashback deteriorates as the mixed gas flow rate increases. It was hot.

The present invention relates to a completely new technique developed in view of these conventional drawbacks.

<Means for Solving the Problems> The present invention provides a welding/cutting torch in which preheated oxygen and fuel gas are mixed inside the torch, in which the gas is generated from the tip of the nozzle in the supply side passage of the preheated oxygen injector hole in the gas mixing section. This is a gas welding and cutting torch constructed by inserting a buffer made of porous material that can absorb straight flashback pressure.

<Function> As described above, the present invention includes inserting a buffer made of a porous material capable of absorbing the straight flashback pressure generated from the tip of the crater into the supply side passage of the preheating oxygen injector hole of the gas mixing section. With this structure, the abnormal pressure generated when flashback spreads from the tip of the nozzle to the gas mixing section via the mixing pipe is absorbed by the porous material inserted into the supply side passage of the preheating oxygen injector hole, and the gas mixing section The return of oxygen to the fuel gas can be made earlier than the return of fuel gas, thereby preventing continuous flashback.

<Example> An example of the present invention will be specifically described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a torch according to the present invention, and an oxygen supply passage 2 and a fuel A gas supply passage 3 is provided separated by a partition wall. An injector head 4 having a tapered outer peripheral surface and an injector hole 2a shaped like a narrow nozzle at the inner end is screwed and fixed to the tip of the oxygen supply passage 2. A buffer 5 made of a porous material is fitted and fixed at the rear end of the injector head 4 so as to form an oxygen bypass passage 2b around its outer periphery. As shown in FIG. 2, this porous material 5 may be made of a metal lump or sintered metal, as long as it has a structure that can absorb abnormal pressure caused by flashback without affecting the base end of the oxygen supply passage 2. I can do it.

A mixing pipe 6 is connected to a common outlet tip of the oxygen supply passage 2 and the fuel gas supply passage 3 and is fixed with a nut 7. The connecting end of the mixing tube 6 is formed into a tapered surface, and together with the outer peripheral surface of the injector head 4, forms a narrow fuel gas supply path 3. Also, the mixed gas passage 8 of the mixing tube 6
The connecting end is configured to have a narrow width, and as it goes toward the tip of the torch 1, the passage expands into a wider portion 8a.
It is composed of the following. Furthermore, a head 9 and a nozzle 10 are provided at the tip of the mixing tube 6.

A mechanism for preventing backfire in the torch 1 configured as described above will be explained.

The fire entering from the crater 10 goes back through the head 9 and the mixed gas passage 8 of the mixing tube 6, and reaches the vicinity of the enlarged portion 8a. At this time, abnormal pressure is applied from the injector head 4 to the oxygen supply passage 2 and the fuel gas supply passage 3 due to backfire, but since the porous material 5 is fitted in the injector head 4, the mixture flows back due to the abnormal pressure. Since the gas is absorbed by the porous material 5, oxygen temporarily flows backward, but is instantly supplied into the mixed gas passage 8 from the injector hole 2a through the detour passage 2b. On the other hand, since the fuel gas supply passage 3 does not have a structure to absorb such abnormal pressure, the fuel gas flows backward due to the backflow of the mixed gas, but is eventually sucked by the oxygen supply pressure and flows into the mixed gas passage 8. Returned and supplied within.

Therefore, in the oxygen supply passage 2, since the porous material 5 is inserted, the range of backflow of the mixed gas is small, and oxygen is instantly supplied into the mixed gas passage 8 through the detour passage 2b. However, since there is a large backflow range on the fuel gas supply passage 3 side, even if oxygen returns to the mixed gas passage 8, the fuel gas does not return at the same time, and the composition of the mixed gas in the mixed gas passage becomes excessive in oxygen. Continuous backfire in the passage enlarged portion 8a can be prevented.

Additionally, experimentally, as shown in FIG. 3, in the injector according to the present invention, the mixing ratio of oxygen (O ₂ ) and fuel gas (AC) is lower than that of the conventional example under the same flow rate of fuel gas, O ₂ / The AC has increased by about 0.4, which can significantly reduce the backfire area inside torch 1.

Further, the ratio of the cross-sectional area S1 of the injector hole 2a to the cross-sectional area S2 of the bypass passage is S as shown in FIG.
The optimal value is 1/S2 of about 1.7, and oxygen (O ₂ )
The cross-sectional area ratio in the range where the mixture ratio O ₂ /AC of and fuel gas (AC) increases by 0.2 or more compared to the conventional example, that is, S
It has been found that a range of 1/S2 of 1.1 to 2.4 is effective in preventing flashback.

Furthermore, it has been found that if the distance between the porous material 5 and the injector hole 2a is 6 mm or more, the ability to prevent continuous flashbacks decreases rapidly, but if the distance is within 6mm, it is effective in preventing continuous flashbacks.

<Effects of the Invention> As described above, the present invention includes inserting a buffer made of a porous material capable of absorbing straight flashback pressure generated from the tip of the crater into the supply side passage of the preheating oxygen injector hole of the gas mixing section. As a result, the abnormal pressure generated when flashback spreads from the tip of the nozzle to the gas mixing section via the mixing tube is absorbed by a buffer made of a porous material inserted into the supply side passage of the preheating oxygen injector hole. It is possible to make the return of oxygen to the gas mixing section earlier than the return of fuel gas, thereby preventing continuous flashbacks and ensuring extremely high safety without melting and damaging the mixing pipe. This has effects such as being able to construct a high-quality torch.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view of a torch according to the present invention, FIG. 2 is an explanatory view of a buffer made of a porous material, and FIG.
4 is an explanatory diagram showing a comparison of the flashback region, FIG. 4 is an explanatory diagram showing changes in the flashback region depending on the ratio of the cross-sectional area of the injector hole and the bypass passage cross-sectional area, and FIG. 5 is an explanatory diagram of a conventional example. 1 and 11 are torches, 2 and 12 are oxygen passages, 2
a, 12a are injector holes, 2b is a bypass passage, 3, 13 are fuel gas passages, 4, 14 are injector heads, 5 is a buffer, 6, 15 are mixing pipes,
7 and 16 are nuts, 8 and 17 are mixed gas passages, 8
a, 17a are passage expansion parts, 9, 18 are instrument heads, 1
0.19 is the crater.

Claims (1)

[Claims] 1. In welding and cutting torches that mix preheated oxygen and fuel gas inside the torch, the supply side passage of the preheated oxygen injector hole in the gas mixing section has a porous hole that can absorb the straight flashback pressure generated from the tip of the nozzle. 1. A gas welding and cutting torch characterized in that it is constructed by inserting a buffer made of a chemical substance.