| Title of Invention | "AN IMPROVED NARROW GAP GAS METAL ARC WELDING TORCH" |
|---|---|
| Abstract | This invention relates to an improved narrow gap gas metal arc welding torch comprising of a copper block provided with atleast two shielding gas inlet for supply of gas therethrough from one end to other end of the block with a contact tip therebetween for wire feeding and water channels inside the block for circulation of water. |
| Full Text | FIELD OF INVENTION This invention relates to an improved narrow gap gas metal arc welding torch. BACKGROUND/PRIOR ART OF THE INVENTION Conventionally, welding processes are generally used for fabrication of thick plate which are such as Submerged Arc Welding (SAW),Shielded Metal Arc Welding (SMAW) and Electro slag welding (ESW). These processes require wider groove area in comparison with narrow gap gas metal arc welding (NG-GMAW). Wide gap results in lower mechanical properties (higher heat input) and productivity of the process. Further, in case of joint preparation for conventional submerged arc welding , cross sectional area of groove is around 3 times (in case of 60 ° groove angle) that of narrow gap. Therefore, 3 times weld metal per unit length is required. Finally, it leads to higher heat input. Further, conventional submerged arc welding (SAW) is expensive in terms of filler metal consumption. Further, when a conventional SMA welding process is known to have been used, it requires a circular torch (as shown in fig. 3). This torch is about 18-20 mm in diameter. Due to the limitations of geometry and dimensions, it can't move inside the narrow groove. Narrow gap gas metal arc welding provides an economical alternative to conventional process for thicker plate, some of narrow gap arc welding torches known in the art are as follo s:- (Table Removed) The said patented inventions are complicated in construction and expensive. Further, each of them requires a coating for insulation and some of them use single layer double pass technique. Single layer double pass takes more time and causes distortion. OBJECTS OF THE INVENTION Objective of this invention is to propose an improved narrow gap gas metal arc welding torch which leads to increase in productivity and reduction in cost. Another object of this invention is to propose an improved narrow gap gas metal arc welding torch which produces sound welded joint. Further object of this invention is to propose an improved narrow gap gas metal arc welding torch which can reach bottom of the narrow gap and is able to travel along the narrow gap. Still another object of this invention is to propose an improved narrow gap gas metal arc welding torch which insures laminar flow of gas. Yet further object of this invention is to propose an improved narrow gap gas metal arc welding torch which is able to carry welding current of 100-300 Amp. Yet another further object of this invention is to propose an improved narrow gap gas metal arc welding torch, contact tip of which is easily replaceable as and when it gets worn out or damaged having long life. STATEMENT OF INVENTION According to this invention there is provided an improved narrow gap gas metal arc welding torch comprising of a copper block provided with atleast two shielding gas inlet for supply of gas therethrough from one end to other end of the block with a contact tip therebetween for wire feeding and water channels inside the block for circulation of water. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein: Fig. la shows: conventional narrow gap gas metal arc welding torch Fig. Ib shows conventional diffuser plate of NG-GMAW torch. Fig. 2 shows different views of conventional narrow gap gas metal arc welding torch. Fig. 3 shows different views of conventional narrow gap gas metal arc welding torch. Fig. 3' shows: conventional gas metal arc welding torch. Fig. 4 shows front view of narrow gap gas metal arc welding torch of the present invention. Fig. 5 shows marcostructure of 50 mm thick mild steel plate welded with the torch of present invention. DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS; Reference may be made to fig. 4 wherein the NG-GMAW torch comprising of 6.0-6.5 mm thick copper block. With this thickness, torch is able to move inside a narrow gap of approximately 12 mm without touching sidewalls of the joint, thus eliminating any possibility of short-circuiting between the torch body and workpiece on its both sides. Therefore, an insulation coating of ceramic is not required to be provided on the torch body. The copper block is disposed with holes (1-5) by drilling as shown in fig. 1 wherein holes (1 and 3) are connected to a copper pipe provided with shielding gas inlet (6) at the end for supply of gas there through to other end of the drilled hole through a brass nipple (7). The brass nipple is provided with a diffuser therein to get effective and reliable shielding. Diffuser comprises stainless steel mesh, which is atleast three in number with a gap therebetween to convert turbulent flow of the gas into laminar flow. Other ends of the holes (1 and 3) are exposed to high temperature. Therefore, to avoid damage of this part, gas tubes of stainless steel are provided, which is replaceable. The gas tubes provides effective shielding during welding. The hole in between the shielding gas inlets is meant for wire feeding. Extreme end of this hole is provided with a contact-tip, which is consumable part of the torch. Contact tip is made of copper and gets damaged in course of time by virtue of service conditions existing in this joint gap. Therefore, it is designed detachably. However, overheating of the contact tip is reduced in the present invention because of mass effect of copper block, which is much higher than the mass of the tip. This leads to high tip life. Therefore, it is not required to replace the same frequently. Upon movement inside the joint gap, the torch gets exposed to high temperature of the arc during welding. To avoid damage to the torch due to high temperature of arc, water cooling channels (8 and 9) are drilled inside the torch body for water circulation. This helps in avoiding overheating of torch. Channels for water circulation are created by drilling blind holes from two right angle directions in such a way that channels are interconnected providing inlet and outlet for water. The openings in the copper block thickness other than inlet and outlet are closed by brazing. In this respect this torch is much different than others. At the same time heat dissipation from the torch is further enhanced, by selecting copper as material for the main body of the torch, which has much higher thermal conductivity and does not allow accumulation of the heat at one point. Copper block has sufficient mass to avoid steep rise in temperature of the block. Further, the torch is having two holes one on each side for attachment during operation. Torch of the present invention is a flat torch, which can enter into and move freely in a narrow groove of for example 12 mm. Torch of the present invention was tried on a number of joints for its ability to carry out desired function. It was found that, average tip life is good and no damage was observed on the torch body. Further, joint obtained with single layer per single pass was good as shown in figure 5. Plate thickness up to 70 mm can be welded using this torch design. It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:- WE CLAIM 1. An improved narrow gap gas metal arc welding torch comprising of a copper block provided with atleast two shielding gas inlet for supply of gas therethrough from one end to other end of the block with a contact tip therebetween for wire feeding and water channels inside the block for circulation of water. 2. An improved narrow gap gas metal arc welding torch as claimed in claim 1 wherein the shielding gas inlet is connected to a brass nipple provided with a diffuser. 3. An improved narrow gap gas metal arc welding torch as claimed in claim 2 wherein the diffuser comprises of atleast three stainless steel meshes with a gap therebetween so as to convert turbulent flow of the gas into laminar flow. 4. An improved narrow gap gas metal arc welding torch as claimed in any of the preceding claims wherein the water channels are blind holes provided from two right angle directions in such a way that channels are interconnected providing inlet and outlet for water. 5. An improved narrow gap gas metal arc welding torch as claimed in any of the preceding claims wherein the other end of the block, one end of which is provided with shielding gas inlet is having stainless steel gas tubes, adjacent to the contact tip. 6. An improved narrow gap gas metal arc welding torch as claimedin claim 5 wherein the contact tip is made of copper, which is replaceable. An improved narrow gap gas metal arc welding torch as claimed in any of the preceding claims wherein the copper block is having a thickness of 6.0-6.5 mm.An improved narrow gap gas metal arc welding torch substantially as herein described with reference to the accompanying drawings. |
|---|
| Patent Number | 272564 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Indian Patent Application Number | 629/DEL/2007 | |||||||||
| PG Journal Number | 16/2016 | |||||||||
| Publication Date | 15-Apr-2016 | |||||||||
| Grant Date | 08-Apr-2016 | |||||||||
| Date of Filing | 22-Mar-2007 | |||||||||
| Name of Patentee | DEPARTMENT OF SCIENCE AND TECHNOLOGY (DST) | |||||||||
| Applicant Address | TECHNOLOGY BHAWAN, NEW MEHRAULI ROAD, NEW DELHI-110 016 | |||||||||
Inventors:
|
||||||||||
| PCT International Classification Number | B23K26/14; B23K9/173; B23K26/24 | |||||||||
| PCT International Application Number | N/A | |||||||||
| PCT International Filing date | ||||||||||
PCT Conventions:
|
||||||||||