JP2014005313A - Combustible gas and gas pressure welding method of steel material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustible gas suitable as a substitute gas of acetylene, and to provide a gas pressure welding method of a steel material using the combustible gas.SOLUTION: The combustible gas contains 10% or more but 50% or less by volume of ethylene, and the balance comprising a natural gas and unavoidable impurities. The gas pressure welding method of the steel material is a method for pressure welding the steel material by using the combustible gas as a combustion gas, wherein the combustible gas contains 10% or more but 50% or less by volume of ethylene, and the balance comprising a natural gas and unavoidable impurities.

Description

  The present invention relates to a flammable gas and a gas pressure welding method for a steel material, and more specifically, a flammable gas suitable for gas pressure welding, gas fusing, gas welding, brazing, and the like, and a gas of a steel material using the flammable gas. It relates to the pressure welding method.

Acetylene (C ₂ H ₂ ) is widely used as a combustion gas in gas pressure welding, gas fusing, gas welding, brazing, and the like. Acetylene is excellent in burning rate and burning strength and is suitable as a combustion gas.

  However, acetylene may decompose and explode when stored and transported in the state of compressed gas. Therefore, acetylene is stored and transported in a dissolved gas state dissolved in a solvent such as acetone or dimethylformamide. As a result, acetylene has problems such as being unsuitable for mass transportation using a collection container or a large container.

  On the other hand, it is proposed to use natural gas as a combustion gas instead of acetylene (for example, see Patent Documents 1 to 3).

JP 2006-21233 A JP 2005-224856 A JP 2005-205465 A

  However, when natural gas is used instead of acetylene as the combustion gas, for example, when the gas pressure welding is performed manually, the reducing property of the atmosphere around the pressure welding portion becomes insufficient, and the pressure welding portion may be oxidized. Such oxidation of the pressure contact portion can be suppressed, for example, by disposing a cap made of polyethylene or the like on the pressure contact surface of the steel material to be joined before performing the pressure welding. However, since it is necessary to take such measures, gas pressure welding using natural gas as a combustion gas has a problem that it takes more time than when acetylene is used as a combustion gas. For this reason, natural gas is not always suitable as an alternative gas for acetylene.

  The present invention has been made to address such problems, and an object of the present invention is to provide a combustible gas suitable as an alternative gas for acetylene and a gas pressure welding method for steel using the combustible gas. That is.

  The combustible gas according to the present invention contains 10% by volume or more and 50% by volume or less of ethylene, and is composed of the remaining natural gas and inevitable impurities.

  The present inventor has studied a method for suppressing oxidation of steel materials when performing gas pressure welding, gas fusing, gas welding, brazing, and the like of steel materials using a combustion gas based on natural gas. As a result, by mixing ethylene with natural gas and adjusting the mixing ratio of natural gas and ethylene appropriately, for example, when carrying out gas pressure welding, a cap made of polyethylene or the like is attached to the pressure welding surface of the steel material to be joined. It was found that good gas pressure welding and the like can be achieved without taking any other oxidation control measures such as disposition. That is, by mixing ethylene with natural gas at an appropriate mixing ratio, oxidation of the pressure contact portion during the gas pressure contact can be suppressed. Thus, according to the combustible gas of the present invention, it is possible to provide a combustible gas suitable as an alternative gas for acetylene.

  Here, “natural gas” is a gas defined in JIS K2301 and means a gas mainly composed of methane produced in nature. The component composition is mainly composed of methane, and includes gaseous hydrocarbons, hydrogen, helium, carbon monoxide, carbon dioxide, oxygen and nitrogen. More specifically, general natural gas is mainly composed of about 90% by volume of methane, contains ethane, propane and butane, and other components are less than 1% by volume.

  The combustible gas may be enclosed in a container, and the pressure in the container may be 1 MPa or higher and 14.7 MPa or lower at 35 ° C.

  The combustible gas of the present invention may be produced and used by mixing ethylene gas and natural gas in a place where processing such as gas pressure welding, gas fusing, gas welding, brazing, or the like is performed. On the other hand, the combustible gas of the present invention is manufactured by mixing ethylene gas and natural gas in advance, sealed in a container, and then held in the container, followed by gas pressure welding, gas fusing, gas welding, brazing. It may be transported and used to a place where processing such as attaching is performed. In this case, in order to achieve efficient transportation, it is preferable to increase the pressure in the container. However, if the pressure is increased too much, ethylene may be liquefied at a low temperature and it may be difficult to obtain a desired mixing ratio of ethylene and natural gas at the time of use. By setting the pressure in the container to 1 MPa or higher and 14.7 MPa or lower at 35 ° C., occurrence of such a problem can be suppressed and efficient transportation can be achieved. In order to achieve more efficient transportation, the pressure in the container is preferably 5 MPa or more at 35 ° C., more preferably 10 MPa or more.

  The combustible gas may be used as a combustion gas for pressure welding of steel materials. The combustible gas of the present invention that can be used as an alternative gas for acetylene while suppressing the oxidation of the pressure contact portion is suitable as a combustion gas used for pressure welding of steel materials.

  The steel gas pressure welding method according to the present invention is a steel gas pressure welding method in which a steel material is pressure-welded using a combustible gas as a combustion gas. The combustible gas used in this gas pressure welding method of steel material contains 10 volume% or more and 50 volume% or less ethylene, and consists of remainder natural gas and inevitable impurities.

  According to the gas pressure welding method of a steel material of the present invention, the flammable gas of the present invention that can be used as an alternative gas for acetylene is used as a combustion gas, thereby suppressing oxidation of the pressure welded portion without using acetylene. However, the steel material can be pressed.

  As is apparent from the above description, according to the gas pressure welding method of the combustible gas and steel material of the present invention, a combustible gas suitable as an alternative gas for acetylene, and a gas pressure welding method of steel material using the combustible gas are provided. Can be provided.

  Hereinafter, an embodiment of the present invention will be described. The combustible gas in this Embodiment can be manufactured by filling containers, such as a cylinder, as follows, for example. First, the inside of the container to be filled with combustible gas is depressurized to a desired level. Next, ethylene gas is supplied into the container, and ethylene is contained in the container so that the pressure in the container becomes a pressure necessary for the ratio of ethylene in the combustible gas to be 10% by volume or more and 50% by volume or less. Filled.

  Next, natural gas is supplied into the container filled with ethylene as described above, and the pressure in the container is a pressure necessary for the ratio of ethylene in the combustible gas to be 10 volume% or more and 50 volume% or less. As such, the container is filled with natural gas. As a result, the container is filled with a combustible gas containing 10% by volume or more and 50% by volume or less of ethylene and comprising the remaining natural gas and inevitable impurities. At this time, it is preferable that the pressure in the said container is 1 MPa or more and 14.7 MPa or less in 35 degreeC. In this way, the container is filled with the combustible gas, so that it can be transported, and for example, it can be easily applied as a combustion gas to the pressure welding of steel materials.

  The pressure welding of the steel material using the combustion gas can be performed, for example, as follows. First, a steel material is hold | maintained so that the end surfaces of two steel materials which should be press-contacted, such as a reinforcing bar, contact. Next, a burner having an arcuate portion in which a plurality of craters are arranged in the circumferential direction on the inner peripheral side is arranged so that the end faces of the two steel materials face the contact area. Thereby, the crater of a burner will be in the state located so that the outer periphery of the area | region where the end surfaces of two said steel materials contact may be surrounded. And the mixed gas of the combustible gas and oxygen of this Embodiment with which the said container (cylinder) was filled to the burner is supplied, a flame is formed by igniting this, and the end surfaces of the said steel materials contact. The area is heated and pressure welding is achieved.

  Here, the pressure welding of the steel material may be performed automatically using a robot or the like, or may be performed manually by an operator. Even when the pressure welding is performed manually, oxidation of the pressure welding portion can be easily suppressed by using the combustible gas in the present embodiment as a fuel gas.

  In the mixed gas of natural gas and ethylene, those having ethylene content of 5, 10, 20, 30, 35, and 40% by volume were prepared, and an experiment was conducted in which the steel material was pressure-welded using this. As a result, when the ethylene content was 5% by volume, clear oxidation was confirmed at the pressure contact portion. On the other hand, in the case where the ethylene content was 10% by volume or more, although some oxidation was confirmed on the outer peripheral part of the press contact part in the case of 10% by volume and 20% by volume, good press contact was achieved. It was. Therefore, when focusing on static strength such as tensile strength, it is considered that the ethylene content may be 10% by volume or more. However, the occurrence of the slight oxidation may affect the fatigue strength. Therefore, when steel materials are used for applications that require fatigue strength, it is considered that the ethylene content is preferably 20% by volume or more.

  When filling the flammable gas into a container such as a cylinder, if the ethylene content exceeds 50% by volume, the ethylene liquefies in the container, and the flammable gas having an appropriate mixing ratio can be taken out from the container. There is no possibility. Therefore, the ethylene content is preferably 50% by volume or less.

  The embodiments and examples disclosed herein are illustrative in all respects and should not be construed as being restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The gas pressure welding method of the combustible gas and steel material of the present invention can be applied particularly advantageously to the fuel gas used as an alternative gas for acetylene and the gas pressure welding of the steel material using the fuel gas.

The combustible gas according to the present invention is a combustible gas used as a combustion gas for pressure welding of steel materials , contains 10% by volume or more and 50% by volume or less of ethylene, and consists of the balance natural gas and inevitable impurities. Yes.

The combustible gas of the present invention are prepared by mixing the ethylene gas and natural gas at a location where the gas pressure contact is carried out, it may be used. On the other hand, the combustible gas of the present invention, previously been prepared by mixing ethylene gas and natural gas, after being sealed in a container, transported while being held on the container to the place where the gas pressure contact is carried out And may be used. In this case, in order to achieve efficient transportation, it is preferable to increase the pressure in the container. However, if the pressure is increased too much, ethylene may be liquefied at a low temperature and it may be difficult to obtain a desired mixing ratio of ethylene and natural gas at the time of use. By setting the pressure in the container to 1 MPa or higher and 14.7 MPa or lower at 35 ° C., occurrence of such a problem can be suppressed and efficient transportation can be achieved. In order to achieve more efficient transportation, the pressure in the container is preferably 5 MPa or more at 35 ° C., more preferably 10 MPa or more.

Combustible gas usable present invention while suppressing the oxidation of the pressure contact portion as a replacement gas acetylene is suitable as a combustion gas used for welding of steel materials.

The combustible gas according to the present invention is a combustible gas used as a combustion gas for pressure welding of steel materials, contains 30 % by volume or more and 50% by volume or less of ethylene, and consists of the remaining natural gas and inevitable impurities. Yes.

The steel gas pressure welding method according to the present invention is a steel gas pressure welding method in which a steel material is pressure-welded using a combustible gas as a combustion gas. The combustible gas used in this steel gas pressure welding method contains 30 volume% or more and 50 volume% or less of ethylene, and is composed of the balance natural gas and inevitable impurities.

Claims (4)

  A combustible gas containing 10% by volume or more and 50% by volume or less of ethylene, the balance being natural gas and inevitable impurities.   The combustible gas of Claim 1 enclosed in a container and the pressure in the said container is 1 MPa or more and 14.7 MPa or less in 35 degreeC.   The combustible gas of Claim 1 or 2 used as a combustion gas for the pressure welding of steel materials. A gas pressure welding method for a steel material in which a steel material is pressure-welded using a combustible gas as a combustion gas,
The said combustible gas contains 10 volume% or more and 50 volume% or less ethylene, and consists of the remainder natural gas and an unavoidable impurity, The gas pressure welding method of steel materials.