TWI744567B - Gas cutting nozzle - Google Patents

Abstract

A gas cutting nozzle comprises an inner core rod at least part of which is formed of brass having a high dezincification resistance, and an outer cylinder forming a passage between the outer cylinder and an outer surface of the inner core rod. At least a surface of the through hole through which cutting oxygen passes or a front end portion of the inner core rod is formed of brass having a high dezincification resistance.

Description

Gas cutting nozzle

The invention relates to a gas cutting nozzle.

This case claims priority based on Special Application No. 2017-228387 filed in Japan on November 28, 2017, and uses its content here.

When using the gas cutting nozzle for gas cutting of the steel plate, when the gas is cut off, the spatter (molten iron) adheres to the end surface or the internal gas path, which will cause the gas flow to become uneven and reduce the gas cut performance.

Generally speaking, as a method of restoring the gas cutting performance, a method of removing sputters attached to the gas path of the inner core rod of the gas cutting nozzle is adopted. Since the inner mandrel with many processing parts mostly uses materials with good machinability (for example, brass), it is easy to damage the shape of the inner mandrel when removing the adhered sputter. As a result of damage to the shape of the inner core rod, sometimes the gas cutting performance of the gas cutting nozzle is reduced.

With reference to Patent Documents 1 to 3, a gas cutting nozzle is designed. The gas cutting nozzle is designed to prevent the adhesion of sputters to the gas path of the gas cutting nozzle or the cleaning operation accompanied by the removal of the adhered sputters. The reduction of gas cut-off performance caused by the shape damage of the mandrel. For example, in the gas cutting nozzle described in Patent Document 1, the inner core rod is formed of stainless steel or ceramic to prevent damage to the nozzle shape. Also, it’s also designed with internal Formed to prevent damage to the nozzle shape. In addition, a gas cutting nozzle is also designed to prevent damage to the shape of the inner core rod by performing surface treatment based on plating on the inner core rod.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2000-249315

[Patent Document 2] Japanese Patent Laid-Open No. 2016-147291

[Patent Document 3] Japanese Patent Laid-Open No. 6-74426

However, whether it is the case where the inner core rod is formed of stainless steel or ceramics, or the case where the inner core rod is surface-treated by electroplating, compared with the case where the inner core rod is formed with general material brass, there is a higher manufacturing cost. The problem.

The present invention was completed in consideration of the above circumstances, and its object is to provide a gas cutting nozzle that does not increase the manufacturing cost and is less likely to cause a decrease in gas shutoff performance.

In order to solve the above-mentioned problems, the present invention proposes the following methods.

The gas cutting nozzle of the first aspect of the present invention includes: an inner core rod, at least a part of which is formed of brass with high dezincification resistance; and an outer nozzle, which forms a passage with the outer surface of the inner core rod, The above-mentioned inner core rod can also be formed of brass containing at least 59.0-67.0% by weight of Cu, 1.0-4.0% by weight of Pb, 0.8% by weight or less of Fe, 0.1-2.3% by weight of Sn, and the remainder as Zn. .

According to the second aspect of the present invention, in the gas cutting nozzle of the first aspect, the inner core rod may have at least the surface of the flow hole for cutting off oxygen to be formed of brass with high dezincification resistance.

According to the third aspect of the present invention, in the gas cutting nozzle of the first aspect, at least the surface of the front end portion of the inner core rod may be formed of brass with high dezincification resistance.

According to the gas cutting nozzle of the present invention, it is possible to provide a gas cutting nozzle which does not increase the manufacturing cost and is not prone to decrease the gas cutting performance.

100: Gas cutting nozzle

1: Internal core rod

1a: Flow hole

1b: Yamabe

1c: slot

1g: outer surface

1gt: Outer surface of front end

2: External spout

2n: inner surface

2ns: the inner surface of the tip

3: access

5: spout metal parts

5a: Cut off the oxygen port

5b: Preheating oxygen port

5c: Combustion gas port

Fig. 1 is a diagram showing the overall configuration of the gas cutting nozzle of this embodiment.

Figure 2 is a bottom view of the gas cutting nozzle.

Figure 3 is a graph showing the measurement results of the number of perforations in the durability test of the internal core rod.

Figure 4 is a graph showing the measurement results of the number of perforations until it is determined that maintenance is required.

Fig. 5 is a graph showing the measurement result of the number of perforations in the durability test based on the evaluation of the quality of the cut surface of the gas cut.

Figure 6 is a graph showing the number of round trips of the nozzle cleaning needle in the evaluation of the maintenance resistance of the internal core rod.

1 to 2, an embodiment of the present invention will be described. Furthermore, in order to facilitate the observation of the drawings, the dimensions of each component have been appropriately adjusted.

Fig. 1 is a diagram showing the overall configuration of the gas cutting nozzle 100 of this embodiment. Fig. 2 is a bottom view of the gas cutting nozzle 100 of Fig. 1.

The gas cutting nozzle 100 is a nozzle used when cutting steel plates or the like using a hydrocarbon gas such as propane gas, LNG, or a gas such as hydrogen.

The gas cutting nozzle 100 is provided with an inner core rod 1 having a flow hole 1 a for cutting off oxygen, an outer nozzle 2, and a nozzle metal member 5.

As shown in Fig. 1, the inner core rod 1 has a long cylindrical shape, and has a shape that becomes narrower as the bottom surface close to the front end side. In addition, as shown in FIGS. 1 and 2, the inner core rod 1 has a flow hole 1a extending along the central axis of the longitudinal direction, and the flow hole 1a communicates with the external space on the bottom surface.

In addition, as shown in FIGS. 1 and 2, on the front end side of the inner core rod 1, that is, on the outer surface 1gt of the front end portion, a gear-shaped slit portion including a mountain portion 1b and a groove 1c is formed.

The inner core rod 1 is screwed to the spout metal fitting 5 on the side opposite to the front end side, that is, the base end side, and the inner core rod 1 is fitted into the spout metal fitting 5 to be integral with each other.

The inner core rod 1 is formed of brass with high dezincification resistance (hereinafter referred to as "dezincification resistant brass"). The inner core rod 1 is formed of brass which has high thermal conductivity and heat resistance and high economic efficiency such as manufacturing cost. In addition, since there are many processed parts such as gear-shaped slits including ridges 1b and grooves 1c in the inner mandrel 1, brass is also suitable as the material of the inner mandrel 1 from the viewpoint of machinability .

In addition, the inventors analyzed the results and found that dezincification-resistant brass, which is generally used in water pipes and other water parts to prevent dezincification, is suitable as a material for the inner core rod 1. Here, the so-called dezincification phenomenon refers to the phenomenon that the zinc contained in the brass is separated from the brass. For dezincification resistant brass In running water parts such as water pipes, for example, when exposed to chlorine-sterilized tap water for a long period of time, it can better prevent the dezincification phenomenon of zinc with a high ionization tendency due to electrolytic corrosion.

For the internal core rod of the previous gas cutting nozzle, it is believed that there is no part exposed to tap water, so that the dezincification phenomenon of brass will not occur. However, the inventors found that the previous gas cutting In the inner core rod of the spout, the dezincification phenomenon of brass occurs due to the heating when the gas is cut off.

The inner core rod with dezincification phenomenon has a state with red sponge-like copper remaining on the surface, and the structure becomes porous and becomes brittle. Therefore, in the cleaning operation of removing the adhering spatter (molten iron) of brass with dezincification phenomenon, the front end of the inner core rod or the shape of the circulation hole of the inner core rod is easy to be damaged. As a result, it is easy to reduce the gas cutting The gas cut-off performance of the nozzle. For example, just because the gas path of the through hole is damaged with a concave-convex shape of about 3 μm, the gas shutoff performance will be greatly reduced. In addition, since the roughness of the brass in which the dezincification phenomenon occurs will increase, it is easy to adhere to the spatter. As a result, the number of cleaning operations for removing the adhered spatter will increase.

On the other hand, since the inner core rod 1 of the gas cutting nozzle 100 of this embodiment is formed of dezincification resistant brass, the occurrence of the dezincification phenomenon of the brass as described above can be preferably reduced. As a result, it is possible to preferably reduce the occurrence of a decrease in the gas shutoff performance caused by the damage to the shape of the inner core rod 1 accompanying the cleaning operation for removing the spatter.

Here, the so-called dezincification-resistant brass refers to brass that meets the evaluation criteria of ISO6509, for example.

In the ISO6509 dezincification test of the dezincification resistant brass used for the formation of the inner mandrel 1, the maximum dezincification depth is 200μm or less, preferably 50μm or less. Used for the formation of the inner core rod 1 Zinc brass is, for example, brass containing the components shown in Table 1. Furthermore, in the remainder shown in Table 1, unavoidable impurities are included in addition to Zn.

The inner core rod 1 is preferably formed of dezincification-resistant brass, and the β layer that is prone to dezincification is eliminated by heat treatment, thereby improving the dezincification resistance.

As shown in Figures 1 and 2, the outer nozzle 2 is a long cylindrical shape. When viewed in the direction of the central axis of the inner mandrel 1, it fits into the inner mandrel 1 in a concentric shape and is inside the outer nozzle 2. Between the surface 2n and the outer surface 1g of the inner core rod 1 is formed a path 3 of a mixed gas formed by a mixture of preheated oxygen and combustion gas.

As shown in Fig. 2, the passage 3 communicates with the external space on the bottom surface. Furthermore, as shown in FIG. 2, the bottom surface side of the outer nozzle 2, that is, the inner surface of the tip portion 2ns is fitted to the outer peripheral portion of the mountain portion 1b of the inner core rod 1.

In this embodiment, the outer spout 2 is a different body from the inner core rod 1. Therefore, the material of the outer spout is different from the material of the inner core rod 1, and may be formed of, for example, copper.

Furthermore, the outer spout 2 can also be formed integrally with the inner core rod 1. In this case, the outer spout 2 is also formed of dezincification-resistant brass.

As shown in FIG. 1, the nozzle metal piece 5 is provided with a cut-off oxygen port 5a communicating with the flow hole 1a, and a preheating oxygen port 5b and a combustion gas port 5c communicating with the passage 3.

Next, the gas cutting operation using the gas cutting nozzle 100 will be described.

Combustion gas such as preheated oxygen and propane gas is fed into the passage 3 from the preheated oxygen port 5b and the combustion gas port 5c and mixed, and the mixed gas is ejected to the outside to generate a preheated flame. At the same time, the cut-off oxygen gas is ejected from the cut-off oxygen port 5a through the flow hole 1a.

The cutting start part of the steel plate is heated to the ignition temperature by the preheating flame sprayed from the passage 3, and the cutting oxygen is sprayed from the circulation hole 1a toward the cutting start part of the steel plate in a jet shape. The cut-off oxygen is sprayed to burn the iron in the steel, and the heat is used to melt the base material. At the same time, using the mechanical energy of cutting off the oxygen jet, the combustion products are blown away and removed in a groove shape, thereby cutting off. A part of the blown combustion product (sputter) is in contact with the circulation hole 1a, etc., but the internal core rod 1 is not prone to dezincification of surface roughening, so the spatter is not easy to adhere.

(One effect of the implementation form)

According to the gas cutting nozzle 100 of the present embodiment, since the dezincification phenomenon of surface roughening is unlikely to occur, the sputtering material is not easy to adhere. In addition, since the dezincification phenomenon in which the surface becomes brittle is less likely to occur, it is less likely to cause damage to the shape of the inner core rod 1 accompanying the cleaning operation of removing the adhered sputter. With these effects, the reduction in the gas cutting performance of the gas cutting nozzle 100 can be better reduced.

Above, one embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and also includes design changes that do not depart from the scope of the spirit of the present invention. In addition, the constituent elements shown in the above-mentioned embodiment and the modified examples shown below can be combined as appropriate.

(Modification 1)

In the above embodiment, the shape of the portion where the mixed gas is ejected from the gas cutting nozzle 100 is a gear-shaped slit portion, but the shape of the portion where the mixed gas is ejected is not limited to this. The shape of the part where the mixed gas is sprayed may also be six small holes (quincunx-shaped) arranged around the circulation hole 1a. The shape of the part where the mixed gas is ejected may be any shape as long as it is formed to surround the circumference of the flow hole 1a for cutting off the ejection of oxygen.

(Modification 2)

In the above embodiment, the entire inner core rod 1 is formed of dezincification-resistant brass, but the aspect of the inner core rod is not limited to this. Regarding the inner mandrel 1, as long as the part where sputtering is easy to adhere, such as the gear-shaped slit of the inner mandrel, or the front end of the inner mandrel, or the circulation hole of the inner mandrel, is made of dezincification-resistant brass. .

[Example]

Hereinafter, the present invention will be described in more detail with examples, but the present invention is not limited to the following examples.

(Experiment 1)

Carry out the durability test of the inner core rod of the gas cutting nozzle. Continuous perforation (opening) of the steel plate. When the preheating flame and cutting off the flow of oxygen are found to be uneven (visible air flow becomes shorter, etc.), it is judged that a certain amount of sputter is attached to the inner core rod, etc. The gas path is used for cleaning operations to remove sputters. When the flow of preheating flame and cutting off oxygen is still uneven even if cleaning is performed, it is judged that the gas cutting nozzle has reached the life of the product, and the total number of perforations so far is measured.

Table 2 shows the types of internal mandrels of gas cutting nozzles used for durability tests. Comparative Example 1 is the previous internal mandrel made of brass with low dezincification resistance. Comparative Example 2 is an internal mandrel in which the flow holes of the internal mandrel of Comparative Example 1 are chromium-plated. Example 1 is the inner core rod 1 of the above-mentioned embodiment.

Furthermore, in the dezincification corrosion test according to ISO6509, the inner core rod 1 of Example 1 is formed of brass with a maximum dezincification depth of 50 μm or less.

Figure 3 shows the measurement results of the number of perforations. The result is the average of the measurement results of a plurality of samples. In Comparative Example 1 of the previous product, the average number of perforations until the life of the product was about 50 times. On the other hand, in Example 1, the average number of perforations until the life of the product was about 500 times. Compared with Comparative Example 1, the product life of Example 1 is significantly longer. It is inferred that this is because the internal core rod 1 of Example 1 is made of dezincification-resistant brass, and the sputter is not easy to adhere. In addition, the shape of the internal core rod 1 is not easily damaged when the adhered sputter is removed. Increase product life.

As shown in FIG. 3, in Comparative Example 2 in which chromium plating is applied to the flow holes of the inner core rod, the average number of perforations until the product life is about 400, which is significantly longer than that of Comparative Example 1. It is inferred that this is because the surface hardness of the inner core rod is increased by chrome plating. When the adhered sputter is removed, the shape of the inner core rod is not easily damaged, thus increasing the life of the product. However, compared with the internal core rod 1 of Example 1, the manufacturing cost of the internal core rod of Comparative Example 2 in which chromium plating is applied is higher.

(Experiment 2)

Secondly, measure the number of perforations until the need for maintenance of the gas cutting nozzle (removal of adhering sputters). Continuous perforation (opening) of the steel plate is carried out. When the flow of preheating flame and cutting off oxygen is found to be uneven (visible air flow becomes shorter, etc.), it is judged that maintenance is required. The type of the inner core rod of the gas cutting nozzle used in experiment 2 is the same as that in experiment 1.

The judgment of the necessity of maintenance is divided into three levels.

"Maintenance level 1" is a situation where it is judged that the gear-shaped slits of the outer spout and the inner mandrel need to be repaired.

"Maintenance level 2" is a situation where it is judged that the maintenance of the maintenance level 1 is insufficient, and further maintenance of the front end of the inner mandrel is required.

"Maintenance level 3" is a situation where it is judged that the maintenance of the maintenance level 2 is insufficient, and further maintenance of the circulation hole of the inner mandrel is required.

In Fig. 4, the measurement results of the number of perforations until it is determined that maintenance is necessary for each maintenance level are shown.

As shown in FIG. 4, compared with Comparative Example 1 and Comparative Example 2, in Example 1, the number of perforations until it is determined that maintenance is necessary is greater. In particular, in Example 1, the number of perforations until it is determined that the maintenance of the maintenance level 3 is necessary. It is inferred that this is because Embodiment 1 can better prevent the sputter from adhering to the flow hole 1a of the inner core rod 1.

(Experiment 3)

Carry out the durability test of the inner core rod of the gas cutting nozzle based on the evaluation of the quality of the cut surface of the actual gas cutting. The gas shut-off was performed under the shut-off conditions shown in Table 3. The type of the inner core rod of the gas cutting nozzle used in Experiment 3 is the same as that in Experiment 1.

The quality of the cut surface must be evaluated in the following situations: (a) the length of the visible air flow is confirmed every 5 times of perforation, the length of the visible air flow is extremely shortened, or (b) the case of every 25 times of perforation.

When the quality of the cut surface deteriorates, perform the gear-shaped slit of the outer spout and the inner mandrel (maintenance level 1), the front end of the inner mandrel (maintenance level 2), and the circulation hole of the inner mandrel (maintenance level 2). For maintenance level 3), evaluate the quality of the cut surface again. When the quality of the cut surface is no longer improved even after maintenance, it is judged that the gas cutting nozzle has reached the life of the product, and the total number of perforations so far is measured.

Figure 5 shows the measurement results of the number of perforations. In the evaluation based on the quality of the cut surface in Example 1, compared with Comparative Example 1, the product life was significantly longer. According to investigation, in Example 1, the inner core rod 1 is formed of dezincification-resistant brass, and the spatter is not easy to adhere. Moreover, when the adhered sputter is removed, the shape of the inner core rod 1 is not easily damaged, so the product Longer life span.

Table 4 shows the number of perforations performed in Experiment 3 until spatters that cannot be removed during maintenance are generated. In either case, after the spatter that cannot be removed is generated, it is judged that the gas cutting nozzle has reached the end of the product life. It is inferred that this is because the occurrence of sputtering that cannot be removed has a greater impact on the quality of the cut surface. In addition, it is inferred that in terms of prolonging the life of the gas cutting nozzle, it is very important to prevent the adhesion of unremovable sputters.

(Experiment 4)

Secondly, evaluate the maintenance-resistant performance of the internal core rod. In Experiment 4, the nozzle cleaning made of stainless steel was used to repair and maintain the flow hole of the inner core rod. The length of the visible air flow was measured every time the nozzle cleaning needle was reciprocated inside the flow hole 10 times. Measure until the airflow is longer than that at the beginning of the measurement The number of round trips of the nozzle cleaning needle until the temperature becomes shorter. In maintenance, force is applied in such a way that only one of the circulation holes is worn.

Figure 6 shows the measured number of round trips of the nozzle cleaning needle. Compared with Comparative Example 1, Comparative Example 2 and Example 1 have more reciprocating times, that is, higher durability for maintenance. In particular, the investigation revealed that in Comparative Example 2, the surface was hardened by chromium plating, so the durability was improved.

On the other hand, regarding the product life as a gas cutting nozzle, as shown in the results of Experiment 1 to Experiment 3, Example 1 is longer than Comparative Example 2. That is, it is inferred that, compared to the characteristic surface hardness of Comparative Example 2, the characteristic of Example 1, that is, the resistance to dezincification is more important for the life of the product as a gas cutting nozzle.

(Experiment 5)

For reference, the experimental results about the dezincification phenomenon that occurred in the gas cutting nozzle are explained.

Before heating and after heating (10 minutes and 20 minutes later), the composition analysis of the previous internal core rod made of brass with low dezincification resistance was carried out. The inner core rod is heated by the same configuration and procedure as when the steel plate is cut using propane gas.

The analysis results are shown in Table 5. Due to heating, the composition of zinc (Zn) is reduced and the composition of copper (Cu) is increased. This is because dezincification caused by the evaporation and oxidation of zinc occurs in the inner core rod due to heating. It is considered that the dezincification phenomenon occurred more significantly in the surface part of the inner core rod compared with the result of the component analysis shown in Table 5.

[Industrial availability]

The invention can be applied to gas cutting nozzles that use hydrocarbon gases such as propane gas, LNG, or gases such as hydrogen.

100: Gas cutting nozzle

1: Internal core rod

1a: Flow hole

1b: Yamabe

1c: slot

1g: outer surface

1gt: Outer surface of front end

2: External spout

2n: inner surface

2ns: the inner surface of the tip

3: access

5: spout metal parts

5a: Cut off the oxygen port

5b: Preheating oxygen port

5c: Combustion gas port

Claims (4)

A gas cutting nozzle, comprising: an inner mandrel, at least a part of which is formed of brass with high dezincification resistance; and an outer nozzle, which forms a passage with the outer surface of the inner mandrel, the inner mandrel is formed It is made of brass containing at least 59.0~67.0% by weight of Cu, 1.0~4.0% by weight of Pb, 0.8% by weight or less of Fe, 0.1~2.3% by weight of Sn, and the remaining part is made of Zn. Fe in the brass The sum of Sn and Sn is 0.3% by weight or less, and the outer nozzle is concentrically fitted to the inner mandrel when viewed in the direction of the central axis of the inner mandrel. The gas cutting nozzle according to claim 1, wherein at least the surface of the flow hole for cutting off the passage of oxygen of the inner core rod is formed of brass with high dezincification resistance. The gas cutting nozzle according to claim 1, wherein at least the surface of the front end portion of the inner core rod is formed of brass with high dezincification resistance. The gas cutting nozzle according to claim 1, wherein a gear-shaped slit portion composed of a mountain portion and a groove is formed in the inner core rod.

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