Abstract:
A gas cutting torch for the fusion-cutting such iron materials as steel frames or iron plates by dint of flames, is equipped with a pilot fire port in the vicinity of a main cutting tip. A fire is set to this pilot fire port by means of an ignition unit. A fire is set to the main cutting tip by the pilot flame which has been formed on the pilot fire port. So that the pilot fire port functions as an automatic ignition service against the main cutting tip.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a gas cutting torch for fusion-cutting the iron materials like steel frames and iron plates by jetting out of the main cutting tip the mixed gas obtained by mixing gas and oxygen for igniting it, and thus by utilizing the main flame which has been formed on the main cutting tip. 
     This type of gas cutting torch adopts conventionally the way of setting a fire by utilizing a separately installed ignition device or lighter. 
     The reason for it is to design the gas cutting torch in a lighter-in-weight and compacter-in-size version and to alleviate an operator&#39;s fatigue or to reduce the operators inconvenience because, in case of a manual gas cutting torch, the operator holds it in one of his hands and performs the fusion cutting work while moving the torch at his disposal. 
     However, in case of the gas cutting torch, there is a need for extinguishing the fire from time to time during its usage, and it is troublesome to reset a fire using a lighter on each of such occasions. Moreover, holding the gas cutting torch in one hand and handling the lighter with the other hand at a high platform, for example at the construction on-site for a building or a bridge may involve a danger for the operator to fall down from it since both his hands are occupied. 
     SUMMARY OF THE INVENTION 
     The invention makes it possible to automatically set a fire of a gas cutting torch, without using a lighter; to a gas cutting torch. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The embodiment example of this invention can further be known into details with reference to FIG. 1 through FIG. 7. 
     FIG. 1 is a side elevational view of a gas cutting torch equipped with the device for automatically setting a fire. 
     FIG. 2 is a top plan view of the gas cutting torch shown in FIG. 1; 
     FIG. 3 is a sectional view taken along the line A--A line of FIG. 2. 
     FIG. 4 is a sectional view taken along the line B--B of FIG. 1; 
     FIG. 5 is a sectional view taken along the line of C--C of FIG. 1; 
     FIG. 6 is a front elevational view; the direction of the line D--D; and 
     FIG. 7 is a sectional view taken along the line E--E of FIG. 2. 
    
    
     DETAILED DESCRIPTION 
     A pilot fire port 8 for the automatic ignition service in this invention is installed in a nozzle or neighbourhood of the main cutting tip 2 while the ignition unit 15 for setting a fire to the pilot fire port 8 as well as its control section are mounted in a vicinity of the handle section 1a. 
     A gas cutting torch main body 1, which can be held in one hand by gripping the handle section 1a. 
     The main cutting tip 2 is supported by a gas pipe 6 and an oxygen pipe 7 both extending forward from the handle section 1a. 
     In FIG. 3, a mixture section 2a of gas with oxygen is built up inside the main cutting tip 2; mixed gas and oxygen which have entered into the main cutting tip 2 from the mixed gas pipe 6 and the oxygen pipe 7 are further mixed in the mixture section 2a. However, at the time of heating a metal material, only the mixed gas jets out of the tip of main cutting tip 2. 
     A gas supply port 3 is provided at to the rear edge of handle section 1a and it has a gas supply valve 3c which is controlled by a knob 3a. An oxygen supply port 4 is also located at the handle section 1a. 
     A mixture chamber 5 of gas with oxygen located inside the front area of handle section 1a, and the gas which has entered inside the handle section 1a from the gas supply port 3 passes through a back-fire or flashback preventive unit 18, which is to be described later, via a gas passage 3b and enters into this mixture chamber 5. Oxygen which has entered from the oxygen supply port 4 passes through the oxygen passage 4a inside the handle section 1a and is branched inside the front area of the handle section 1a. One branch enters into the needle valve 10 inside the mixture chamber 5 via the branch channel 4b, and its volume is adjusted by the needle 10a. This branch is mixed with the gas in the mixture chamber 5 and led to the main cutting tip 2 from the mixed gas pipe 6. 
     The gas which has entered from the gas supply port is branched to the pilot gas passage 3d by means of the valve 3c. This gas passes through the pilot gas pipe 9 from the pilot gas valve 12 and is led to the pilot fire port 8 which is mounted to the neighbourhood of the main cutting tip 2. The Electrodes 8a for spark discharge are installed to the tip of pilot fire port 8, and the pilot fire port 8 is shielded by the cover 8b. And a knob is provided for controlling the needle 10a. 
     A piezoelectric ignition service lever 13 extends above to the front upper face of handle section 1a, and this ignition lever can be slided to the front side. And if this ignition lever 13 is slid to the front side, the pilot valve 12 is opened and the gas is supplied to the pilot port 8 via the pilot gas pipe 9. At the same time, the piezoelectric ignition unit 15 is actuated for generating a high voltage and discharges electricity in electrodes 8a. By this electric discharge, a fire is set to the gas being jetted out of the pilot fire port 8. For reference, the piezoelectric ignition unit is the device utilizing the officially known piezoelectric effect. 
     An the oxygen valve 16 is installed on the side of another branch channel 4c which has branched the oxygen channel 4a into the branch channel 4b, and this oxygen valve 16 can be opened or closed by means of the knob 17. The downstream side of this valve 16 is interlocked with the oxygen pipe 7. 
     A back fire preventive unit 18 is situated on upstream of the mixture chamber 5 in the gas passage 3b and is incorporated into the front area of handle section 1a, in which the back fire preventive device or filter 18a made of sintered metal is incorporated. Thi back fire preventive device 18a is fitted detachably inside the handle section 1a by the retainer nut 18b. 
     The operation of the gas cutting torch is to be explained below: 
     First, the gas supply port 3 and the oxygen supply port 4 are connected to the gas and oxygen cylinders respectively using the hoses. When respective valves on the side of cylinders are opened for supplying the gas and the oxygen, the gas and the oxygen are led to the mixture chamber 5 respectively through the gas passage 3b and the oxygen channel 4a, and they are mixed in this chamber. This mixture ratio is controlled by the opening degree of the needle 10a contained in the needle valve 10. On the other hand, the gas which has entered the pilot gas passage 3d from the valve 3c is stopped by the pilot gas valve 12. The oxygen entering the oxygen channel 4a and flowing to the side of oxygen pipe 7 is stopped by the oxygen valve 16. 
     Next, when the ignition lever 13 is slid to the front side, the pilot gas valve 12 is opened, and the gas is flows to the pilot fire port 8 and also the trip arm 15a of piezoelectric ignition unit 15 is actuated, generating a spark discharge between the electrodes 8a. As a result, the pilot flame is formed in the pilot fire port 8. 
     When a fire has been set to this pilot fire port 8, control the knob 11 for opening the needle 10a and for mixing the gas with the oxygen, and cause it to flow to the side of main cutting tip 2 via the mixed gas pipe 6. When the mixed gas is jetted out of the main cutting tip 2, a fire is shifted to it from the pilot flame. After this fire shift, when the operators hand is released from the ignition lever 13, this lever is reset automatically by a spring for closing the pilot gas valve 12, and the pilot flame of pilot fire port 8 goes out. Next, the knob 11 is adjusted for the needle valve for mixed gas for adjusting the fire intensity, and carry out the heating work prior to the fusion cutting by use of the main flame which has been formed in the main cutting tip 2. 
     When the heating work is through, the oxygen valve 16 is opened by use of the knob 17 for sending out a great deal of oxygen against the main cutting tip 2 and for forming a jet flame, or an intensive flame for cutting service, to the main cutting tip 2, and perform the cutting work. 
     When the work has been completed, all the valves are closed. 
     Whats more, as the procedure for setting a fire to the main cutting tip 2, it is also acceptable to have the mixed gas first jetted out of the main cutting tip 2 for setting later a fire to the pilot fire port 8, thereby igniting the main cutting tip 2 by use of the said pilot flame. 
     The pilot fire port is mounted in the neighbourhood of the main cutting tip for forming a pilot flame on this pilot fire port while controlling the one-touch type ignition lever. The ignition can be achieved by forming a pilot flame at the pilot fire port and by shifting a fire to the main fire port through the use of the pilot flame, this invention eliminates the need for using a lighter as necessary in the past in setting a fire and can achieve an enhanced workability and safety. 
     In addition, this invention can also be applied to so-called automatic type gas cutting torch, which is not a manual, for fusion cutting of metals while moving it mechanically on the fusion cutting line.