201141652 六、發明說明： 【發明所屬之技術領域】 本發明係關於在內部讓預熱氧和燃料氣體混合之吹管 混合型的切割氣炬，特別是關於可防止逆火之切割氣炬。 【先前技術】 在工地將鋼板切斷時，大多是使用吹管混合型的小型 手持式切割氣炬。吹管混合型的切割氣炬的情況，是在主 體側設置燃料氣體閥、預熱氧閥及吸引構件。此外，主體 和用來裝設氣體切割火口之氣炬頭是經由混合氣體管來連 接，在該混合氣體管的內部設有：燃料氣體和預熱氧的混 合部。 手持式切割氣炬的情況，大多是使用在營建工地和拆 卸工地，而大多面臨嚴苛的使用方式。因此，容易發生氣 體切割火口的過熱、焊濺物的附著所造成之混合氣體噴射 孔的堵塞等，伴隨著此，可能產生逆火而不得不中斷切割 作業。 特別是當逆火前進到切割氣炬的主體側或燃料氣體的 供應側的情況，有發生切割氣炬的熔損、供應燃料氣體之 軟管破損等之虞。因此，爲了防止逆火已有幾個方案被提 出。 例如，專利文獻1所記載的切割氣炬，是在吸引構件 (噴射預熱氧並吸引燃料氣體）的內部設置緩衝器。緩衝 器，是在金屬製的圓筒形成複數個孔而構成，或是在金屬 -5- 201141652 製圓筒的外周形成複數個溝槽而構成，或是由具有透氣性 的燒結金屬所構成。而且，在發生逆火時，將逆火所伴生 之異常壓力藉由緩衝器吸收，以阻止該異常壓力的傳遞而 防止逆火。 此外，專利文獻2所記載的爆炸性氣體的逆火防止裝 置，是藉由設置在燃料氣體（乙炔氣體）的供應路徑來防 止逆火。該逆火防止裝置具有止回閥機構，在乙炔氣體的 供應方向下游側發生逆火或乙炔之分解爆炸而產生異常壓 力時，對應於所產生的壓力使止回閥動作而能阻止其往上 游側傳遞。 〔專利文獻1〕日本實公平3 -5673 8號公報 〔專利文獻2〕日本特公昭61-37525號公報 【發明內容】 專利文獻1所記載的切割氣炬，在作業中發生逆火時 ，能夠藉由緩衝器來防止該逆火。然而，緩衝器造成流體 阻力變大，在氣炬頭裝設用來切割厚鋼板的氣體切割火口 時，必須提高供應給切割氣炬之氧氣壓力。 此外，專利文獻2所記載的逆火防止裝置，在發生逆 火或乙炔的分解爆炸時，可防止其等往乙炔氣體的供應方 向上游側傳遞。然而，該逆火防止裝置必須組裝於配管路 徑來利用，組裝於切割氣炬的內部會變得大型化且造成構 造過於複雜》 本發明之目的，是爲了提供一種_造簡單且能夠確實 -6- 201141652 地防止逆火之切割氣炬。 爲了解決上述課題之本發明的切割氣炬，係具備：用 來裝設氣體切割火口之氣炬頭、設有切割氧閥和預熱氧閥 和燃料氣體閥之主體、用來連接氣炬頭和主體而讓切割氧 流通之切割氧管、以及用來連接氣炬頭和主體而讓預熱氧 和燃料氣體的混合氣體流通之混合氣體管；該切割氣炬之 特徵在於：在前述混合氣體管之氣炬頭側，形成直徑比該 混合氣體管的內徑更大之收容室，且在該收容室收容著將 金屬板扭轉複數次而形成的扭轉構件。 依據本發明的切割氣炬，在裝設於氣炬頭之氣體切割 火口（以下簡稱「火口」）發生逆火時，該逆火會傳遞至 混合氣體管的內部。此外，在混合氣體管的氣炬頭側，形 成有直徑比混合氣體管的內徑更大之收容室，且在該收容 室收容扭轉構件。因此，逆火所伴生之具有高壓和高溫的 氣體，碰撞扭轉構件後會減低壓力，同時被扭轉構件冷卻 而降低溫度。因此可防止逆火。 【實施方式】 以下，針對本發明之吹管混合型的切割氣炬的構造， 參照第1圖〜第3圖來作說明。吹管混合型的切割氣炬的情 況，可在該氣炬內部讓預熱氧和燃料氣體混合而形成混合 氣體，並將該混合氣體供應給裝設於氣炬頭之火口。 此外，在本發明之「防止逆火」，不是指在裝設於氣 炬頭之火口不讓逆火發生，而是指：在包含火口之切割氣 201141652 炬的燃料氣體供應方向下游側發生逆火時，能防止該逆火 傳遞至上游側。 切割氣炬A的構造是具備：供作業員用手把持以誘導 行走方向之主體1、用來拆裝氣體切割火口 B之氣炬頭2、 用來連接主體1和氣炬頭2之切割氧管3及混合氣體管4。在 主體1之氣炬頭2側的端部設置前部分配構件5，在相反側 的端部設置後部分配構件6，前、後部分配構件5、6是經 由握持管7來連接。因此，在構成主體1之握持管7的內部 構成空間8。 在前部分配構件5形成有：切割氧通路5 a、預熱氧通 路5b及燃料氣體通路5c，在切割氧通路5 a設有切割氧閥9 ，在預熱氧通路5b設有預熱氧閥10。該預熱氧閥10，藉由 具備針體l〇a及與該針體l〇a相對置之噴射器l〇b而具有流 量調整功能，且藉由從噴射器l〇b噴射預熱氧而能吸引來 自燃料氣體通路5 c之燃料氣體。 此外，在後部分配構件6也設有：氧通路6a及燃料氣 體通路6b，在燃料氣體通路6b設置燃料氣體閥1 1。而且， 在形成於握持管7內部之空間8內，呈薄列地配置氧配管1 2 和燃料氣體配管。 在氣炬頭2形成有：火口 B的裝設孔2a、切割氧通路2b 以及混合氣體通路2c，在切割氧通路2b連接切割氧管3, 在混合氣體通路2c連接混合氣體管4。 在混合氣體管4之氣炬頭2側的既定位置形成：直徑比 形成在該混合氣體管4內部之混合氣體通路4a的內徑更大 -8 - 201141652 且具有既定長度之收容室20。又在收容室20收容著將金屬 板扭轉複數次而形成的扭轉構件21，藉由該扭轉構件21可 防止逆火。 混合氣體管4之混合氣體通路4a內之收容室20的形成 位置沒有特別的限定，但較佳爲在儘量接近氣炬頭2的位 置。更佳爲，基於收容室20的加工方法、在該收容室2 0所 收容之扭轉構件21的保持方法等的觀點，來設定其尺寸和 位置。 在本實施例，混合氣體管4係具備：固定於氣炬頭2之 螺紋接管（nipple ) 4b、安裝在主體1的前部分配構件5而 用來促進預熱氧和燃料氣體的混合之混合管4c、以及配置 在螺紋接管4b和混合管4c之間的連接管4d。而且，在連接 管4d之螺紋接管4b側的端部形成收容室20。因此，收容室 20的位置是按照螺紋接管4b的長度來設定。 收容室20的直徑是形成比混合氣體通路4a的內徑更大 。切割氣炬A之混合氣體通路4a的內徑是按照該切割氣炬a 的切割能力來設定。因此，收容室20的直徑無法單一意義 地設定。依據本發明人等的實驗，例如混合氣體通路4a直 徑爲4mm的情況，收容室20的直徑較佳爲約4.5mm〜約 5.0mm。 此外，收容室20的長度雖沒有特別的限定，但較佳爲 能發揮防止逆火功能的長度。在本實施例設定爲約5 0 m m 。藉由在混合氣體管4形成前述收容室20，與收容室20對 應之混合氣體管4的壁厚變得比其他部位更薄。因此其散 -9 - 201141652 熱效果是可期待的。 扭轉構件21，是由金屬板構成，藉由將該金屬板扭轉 複數次，而具有與收容室20的直徑大致相等的外徑且與收 容室20的長度大致相等的長度。而且，在收容於收容室20 時，是在該收容室20形成螺旋狀的兩個通路。該通路的長 度比收容室20的長度更大，當逆火之氣體流過該通路時能 與扭轉構件2 1充分地接觸。因此，逆火之氣體可經由扭轉 構件2 1冷卻。 構成扭轉構件2 1之金屬板的材質沒有特別的限定。但 必須爲可進行穩定的扭轉加工的材料。作爲這種材料，是 包含不鏽鋼鋼板、鋼板、或黃銅板、青銅板等，任一者都 能適當地使用。此外，扭轉構件21的厚度雖是越厚越好， 但過厚時會造成扭轉加工困難。 扭轉構件21之扭轉次數沒有特別的限定。然而，若扭 轉次數少，逆火時之高壓高溫的氣體無法與扭轉構件21充 分地接觸而往上游側逆流，要實現有效的防止逆火會有困 難。 在本實施例，是使用厚度約〇.5mm的不鏽鋼板，藉由 扭轉約3.5次來形成扭轉構件21。藉由採用這種構造的扭 轉構件2 1，當逆火的氣體到達扭轉構件2 1時，該氣體碰撞 扭轉構件2 1的表面且沿著扭轉構件2 1的表面流向上游側。 因此，逆火之氣體經由碰撞扭轉構件21而使該氣體的流速 降低，同時被扭轉構件2 1冷卻。特別是由於混合氣體管4 之對應於收容室20的部位之壁厚比其他部位更薄，因此往 -10 - 201141652 大氣散熱的效果是可期待的。 接著說明依據上述構造的切割氣炬A之防止逆火功能 。起因於切割作業的長時間化、焊濺物之附著於火口 B等 的原因，若在火口 B發生逆火，與該逆火伴生之高壓高溫 的氣體會從火口 B沿著氣炬頭2的混合氣體通路2c逆流，而 從混合氣體管4的混合氣體通路4a到達收容室20，並碰撞 其中收容的扭轉構件2 1。 逆火之氣體，經由碰撞扭轉構件2 1而使壓力降低，伴 隨著此減少流速。再者，由於收容室20的直徑比混合氣體 管4之混合氣體流路4a的內徑更大，在從氣炬頭2側的混合 氣體流路4a到達收容室20的時點，對應於截面積差而使流 速減少。此外，由於逆火之氣體碰撞扭轉構件2 1而沿著該 扭轉構件21表面流過，該氣體被扭轉構件21冷卻而使溫度 降低。再者，由於收容室20的周壁厚度較薄，可期待混合 氣體管4之散熱效果，而能順利地讓逆火氣體的溫度降低 〇 如以上所說明，在火口 B發生逆火之氣體，當到達收 容室20、扭轉構件21時，逆火所伴生之高壓降低，同時逆 火所伴生之高溫也降低。因此，藉由收容室20、扭轉構件 2 1可防止逆火，而避免逆火到達上游側之前部分配構件5 ，因此可確保安全性。 本發明之切割氣炬A，可利用於大致全部的吹管混合 型的手持式氣體切割機。 -11 - 201141652 【圖式簡單說明】 第1圖係說明切割氣炬的構造之側截面圖。 第2圖係說明切割氣炬的構造之俯視圖。 第3圖係說明氣炬頭和混合氣體管的內部構造之截面 圖。 【主要元件符號說明】 A :切割氣炬 B :氣體切割火口 1 :主體 2 :氣炬頭 2a :裝設孔 2b :切割氧通路 2c :混合氣體通路 3 :切割氧管 4 :混合氣體管 4a :混合氣體通路 4b :螺紋接管 4c :混合管 4d :連接管 5 :前部分配構件 5a :切割氧通路 5b :預熱氧通路 5c :燃料氣體通路 -12- 201141652 6 :後部分配構件 6a :氧通路 6b :燃料氣體通路 7 :握持管 8 :空間 9 :切割氧閥 1 〇 :預熱氧閥 l〇a :針體 l〇b :噴射器 1 1 :燃料氣體閥 1 2 :氧配管 20 :收容室 2 1 :扭轉構件BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow-mixing type of cutting torch that internally mixes preheated oxygen and fuel gas, and more particularly relates to a cutting torch that can prevent backfire. [Prior Art] When the steel plate is cut at the construction site, a small hand-held cutting torch of a blower type is often used. In the case of the blow-mixing type cutting torch, a fuel gas valve, a preheating oxygen valve, and an attracting member are provided on the main body side. Further, the main body and the gas torch head for mounting the gas cutting burner are connected via a mixed gas pipe, and a mixture of the fuel gas and the preheated oxygen is provided inside the mixed gas pipe. In the case of hand-held cutting torches, most of them are used in construction sites and demolition sites, and most of them face harsh use. Therefore, it is easy to cause overheating of the gas cutting crater, clogging of the mixed gas injection hole due to adhesion of the splatter, and the like, and this may cause a backfire and the cutting operation has to be interrupted. In particular, when the backfire advances to the main body side of the cutting torch or the supply side of the fuel gas, there is a possibility that the welding torch is melted, the hose for supplying the fuel gas is broken, or the like. Therefore, several proposals have been made to prevent backfire. For example, in the cutting torch described in Patent Document 1, a damper is provided inside the suction member (the preheating oxygen is injected and the fuel gas is sucked). The damper is formed by forming a plurality of holes in a metal cylinder, or forming a plurality of grooves on the outer circumference of the metal -5-201141652 cylinder, or a sintered metal having gas permeability. Further, in the event of a backfire, the abnormal pressure associated with the backfire is absorbed by the damper to prevent the transmission of the abnormal pressure and prevent backfire. Further, the backfire prevention device for an explosive gas described in Patent Document 2 prevents backfire by being provided in a supply path of fuel gas (acetylene gas). The backfire prevention device has a check valve mechanism, and when an anti-backfire or an acetylene decomposition explosion occurs on the downstream side of the supply direction of the acetylene gas to generate an abnormal pressure, the check valve is operated corresponding to the generated pressure to prevent the upstream valve from being moved upstream. Side pass. [Patent Document 1] Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. 61-37525 (Patent Document 2). This backfire is prevented by a buffer. However, the damper causes a large fluid resistance, and when the gas torch head is equipped with a gas cutting crater for cutting a thick steel plate, the oxygen pressure supplied to the cutting torch must be increased. Further, in the backfire prevention device described in Patent Document 2, when a reverse fire or a decomposition explosion of acetylene occurs, it is prevented from being transmitted to the upstream side of the supply of acetylene gas. However, the backfire prevention device must be assembled and used in a piping path, and the inside of the cutting torch is enlarged and the structure is too complicated. The purpose of the present invention is to provide a simple and reliable -6 - 201141652 Ground cutting torch to prevent backfire. The cutting torch of the present invention for solving the above problems includes: a torch head for installing a gas cutting torch, a body provided with a cutting oxygen valve, a preheating oxygen valve, and a fuel gas valve for connecting the torch head a cutting gas pipe for circulating cutting oxygen with a main body, and a mixed gas pipe for connecting the gas torch head and the main body to allow a mixed gas of preheated oxygen and fuel gas to circulate; the cutting torch is characterized by: The gas torch head side of the tube forms a storage chamber having a diameter larger than the inner diameter of the mixed gas pipe, and a torsion member formed by twisting the metal plate a plurality of times is accommodated in the storage chamber. According to the cutting torch of the present invention, when a gas-fired crater (hereinafter referred to as "fire port") installed in the torch head is backfired, the backfire is transmitted to the inside of the mixed gas pipe. Further, on the side of the torch head of the mixed gas pipe, a accommodating chamber having a diameter larger than the inner diameter of the mixed gas pipe is formed, and the torsion member is accommodated in the accommodating chamber. Therefore, the gas with high pressure and high temperature associated with the backfire will reduce the pressure after impacting the torsion member, while being cooled by the torsion member to lower the temperature. Therefore, backfire can be prevented. [Embodiment] Hereinafter, the structure of the blow-mixing type cutting torch of the present invention will be described with reference to Figs. 1 to 3 . In the case of a blow-mixing type of cutting torch, preheating oxygen and fuel gas may be mixed inside the torch to form a mixed gas, and the mixed gas is supplied to a fire port installed in the torch head. In addition, the "anti-backfire" in the present invention does not mean that the backfire is not allowed to occur in the fire mouth of the torch head, but means that the reverse side of the fuel gas supply direction of the torch 41044652 containing the torch is reversed. When the fire is fired, the backfire can be prevented from being transmitted to the upstream side. The configuration of the cutting torch A is provided with: a main body for the operator to grasp by hand to guide the direction of travel, an air torch head for disassembling the gas cutting burner B, and a cutting oxygen tube for connecting the main body 1 and the torch head 2. 3 and mixed gas tube 4. The front partial fitting member 5 is provided at the end of the main body 1 on the side of the flare head 2, and the rear partial fitting member 6 is provided at the opposite end, and the front and rear partial fitting members 5, 6 are connected by the holding pipe 7. Therefore, the space 8 is formed inside the grip tube 7 constituting the main body 1. The front portion distribution member 5 is formed with a cutting oxygen passage 5a, a preheating oxygen passage 5b, and a fuel gas passage 5c, a cutting oxygen valve 9 is provided in the cutting oxygen passage 5a, and a preheating oxygen is provided in the preheating oxygen passage 5b. Valve 10. The preheating oxygen valve 10 has a flow rate adjustment function by providing a needle body 10a and an injector 10b opposed to the needle body 10a, and by spraying preheated oxygen from the injector 10b It can attract the fuel gas from the fuel gas passage 5c. Further, the rear portion fitting member 6 is also provided with an oxygen passage 6a and a fuel gas passage 6b, and a fuel gas valve 11 is provided in the fuel gas passage 6b. Further, in the space 8 formed inside the grip tube 7, the oxygen pipe 1 2 and the fuel gas pipe are arranged in a thin row. The torch head 2 is provided with a mounting hole 2a for the fire port B, a cutting oxygen passage 2b, and a mixed gas passage 2c. The cutting oxygen passage 2 is connected to the cutting oxygen passage 2b, and the mixed gas pipe 4 is connected to the mixed gas passage 2c. At a predetermined position on the side of the gas torch head 2 of the mixed gas pipe 4, a housing chamber 20 having a diameter larger than the inner diameter of the mixed gas passage 4a formed inside the mixed gas pipe 4, -8 - 201141652, and having a predetermined length is formed. Further, the torsion member 21 formed by twisting the metal plate a plurality of times is accommodated in the housing chamber 20, and the torsion member 21 prevents backfire. The position at which the accommodating chamber 20 in the mixed gas passage 4a of the mixed gas pipe 4 is formed is not particularly limited, but is preferably as close as possible to the position of the horn head 2. More preferably, the size and position are set based on the processing method of the storage chamber 20, the method of holding the torsion member 21 accommodated in the storage chamber 20, and the like. In the present embodiment, the mixed gas pipe 4 is provided with a nipple 4b fixed to the torch head 2, and a front portion fitting member 5 attached to the main body 1 for promoting mixing of the preheating oxygen and the fuel gas. The tube 4c and the connecting tube 4d disposed between the nipple 4b and the mixing tube 4c. Further, a housing chamber 20 is formed at an end portion of the connecting tube 4d on the side of the nip 4b. Therefore, the position of the accommodating chamber 20 is set in accordance with the length of the nipple 4b. The diameter of the containing chamber 20 is formed to be larger than the inner diameter of the mixed gas passage 4a. The inner diameter of the mixed gas passage 4a of the cutting torch A is set in accordance with the cutting ability of the cutting torch a. Therefore, the diameter of the containing chamber 20 cannot be set in a single sense. According to experiments by the inventors of the present invention, for example, when the diameter of the mixed gas passage 4a is 4 mm, the diameter of the storage chamber 20 is preferably from about 4.5 mm to about 5.0 mm. Further, although the length of the storage chamber 20 is not particularly limited, it is preferably a length that can prevent the backfire function. In the present embodiment, it is set to about 50 m. By forming the storage chamber 20 in the mixed gas pipe 4, the thickness of the mixed gas pipe 4 corresponding to the storage chamber 20 becomes thinner than other portions. Therefore, its -9 - 201141652 thermal effect is expected. The torsion member 21 is made of a metal plate and has a length equal to the diameter of the storage chamber 20 and is substantially equal to the length of the accommodation chamber 20 by twisting the metal plate a plurality of times. Further, when accommodated in the storage chamber 20, two passages which are spirally formed in the storage chamber 20 are formed. The length of the passage is larger than the length of the containing chamber 20, and can sufficiently contact the torsion member 21 when the backfire gas flows through the passage. Therefore, the backfire gas can be cooled via the torsion member 21. The material of the metal plate constituting the torsion member 21 is not particularly limited. However, it must be a material that can be subjected to stable torsion processing. As such a material, a stainless steel plate, a steel plate, a brass plate, a bronze plate, or the like is included, and any of them can be suitably used. Further, the thickness of the torsion member 21 is as thick as possible, but when it is too thick, it is difficult to torsion. The number of twists of the torsion member 21 is not particularly limited. However, if the number of twisting is small, the high-pressure high-temperature gas in the backfire cannot be sufficiently contacted with the torsion member 21 to flow upstream to the upstream side, and it is difficult to achieve effective prevention against backfire. In the present embodiment, a torsion member 21 is formed by twisting about 3.5 times using a stainless steel plate having a thickness of about 0.5 mm. By using the twisting member 21 of such a configuration, when the backfire gas reaches the torsion member 21, the gas collides with the surface of the torsion member 21 and flows to the upstream side along the surface of the torsion member 21. Therefore, the gas of the backfire reduces the flow velocity of the gas by colliding with the torsion member 21 while being cooled by the torsion member 21. In particular, since the thickness of the portion of the mixed gas pipe 4 corresponding to the storage chamber 20 is thinner than other portions, the effect of heat dissipation to the atmosphere of -10 - 201141652 is expected. Next, the anti-backfire function of the cutting torch A according to the above configuration will be described. Due to the prolonged cutting operation and the adhesion of the spatter to the fire port B, if a backfire occurs in the fire mouth B, the high-pressure high-temperature gas associated with the backfire will follow the torch head 2 from the fire mouth B. The mixed gas passage 2c flows back, and reaches the storage chamber 20 from the mixed gas passage 4a of the mixed gas pipe 4, and collides with the torsion member 21 accommodated therein. The gas of the backfire reduces the pressure by colliding the torsion member 21, which is accompanied by a decrease in the flow rate. In addition, since the diameter of the accommodating chamber 20 is larger than the inner diameter of the mixed gas flow path 4a of the mixed gas pipe 4, the time from when the mixed gas flow path 4a on the side of the lance head 2 reaches the accommodating chamber 20 corresponds to the sectional area. The flow rate is reduced by the difference. Further, since the gas of the backfire collides with the torsion member 21 and flows along the surface of the torsion member 21, the gas is cooled by the torsion member 21 to lower the temperature. Further, since the thickness of the peripheral wall of the accommodating chamber 20 is thin, the heat dissipation effect of the mixed gas pipe 4 can be expected, and the temperature of the backfire gas can be smoothly lowered, as described above, and the gas which is backfire occurs at the crater B, when When the accommodating chamber 20 and the torsion member 21 are reached, the high pressure associated with the backfire is lowered, and the high temperature associated with the backfire is also lowered. Therefore, the backing fire can be prevented by the accommodating chamber 20 and the torsion member 21, and the backfire can be prevented from reaching the upstream part of the fitting member 5, so that safety can be ensured. The cutting torch A of the present invention can be utilized in substantially all of the blow-mix type hand-held gas cutters. -11 - 201141652 [Simple description of the drawings] Fig. 1 is a side sectional view showing the structure of the cutting torch. Figure 2 is a plan view showing the construction of the cutting torch. Figure 3 is a cross-sectional view showing the internal structure of the torch head and the mixed gas pipe. [Description of main components] A: Cutting torch B: Gas cutting burner 1: Main body 2: Torch head 2a: Mounting hole 2b: Cutting oxygen passage 2c: Mixed gas passage 3: Cutting oxygen tube 4: Mixed gas tube 4a : Mixed gas passage 4b: nip pipe 4c: mixing pipe 4d: connecting pipe 5: front partial fitting member 5a: cutting oxygen passage 5b: preheating oxygen passage 5c: fuel gas passage -12- 201141652 6: rear partial fitting member 6a: oxygen Path 6b: Fuel gas path 7: Holding tube 8: Space 9: Cutting oxygen valve 1 〇: Preheating oxygen valve l〇a: Needle body l〇b: Injector 1 1 : Fuel gas valve 1 2 : Oxygen piping 20 : containment chamber 2 1 : torsion member