Abstract:
Two slidable carriages of identical construction are slidably mounted in a welding device side by side and move alternately 180 degrees out of phase with each other in a linear reciprocating movement. Pivotal gripping plates are mounted on the slidable carriages which alternately clamp on selected gaps between flux coating sections of the welding electrode to advance it continuously towards the work piece. Crank shafts are incorporated in the welding device to produce the linear reciprocating movement of the two slidable carriages, and cam wheels and pivotal bars are provided to locate alternately one group of gripping plates in the closed position to carry the welding electrode forward while the other group of gripping plates are in the opened position to facilitate the welding electrode to advance.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a driving system of a welding device for a continuous welding electrode having open gaps formed in its flux coating. The welding device is operative for carrying out continuous welding operation. 
   2. Background Art 
   Continuous welding operation is required to obtain a high quality welding continuously without any intermission. The weld has a strong bond to the work piece and it has a high quality and a desirable smooth surface. Continuous welding operation is carried out by a welding device which advances a continuous welding electrode towards the work piece as well as supplying a high welding current for the operation. The high welding current is supplied to the welding core through open gaps formed in the flux coating on the continuous welding electrode. The welding device also drives the continuous welding electrode towards the work piece in cooperation with these open gaps. Commonly, a complex chain driven mechanism or a series of circulating drive members are provided in the welding device for the above purposes. In the chain drive mechanism a plurality of fingers are provided in evenly spaced positions on a circulating continuous chain. The fingers engage with the same evenly spaced open gaps of the welding electrode to drive it forward towards the work piece. While in the latter system, a series of drive members are circulated continuous through a continuous circulation channel formed adjacent to the welding electrode feeding channel. The drive members have fingers engaging with the open gaps of the welding electrode to drive it towards the work piece. However, both such continuous welding electrode advancing systems are problematic in that the chain in the chain drive system often become slacken due to wear while the series of circulating drive members in the latter case cause rapid wear of the circulation channel as well as the drive members themselves. Therefore, both such known continuous welding electrode driving systems are prone to jamming. Furthermore, such known systems are relatively slow in their operation despite of their complex construction. 
   SUMMARY OF THE INVENTION 
   It is a primary object of the present invention to provide a reciprocating drive system for a welding device of a continuous welding electrode. 
   It is another object of the present invention to provide a welding electrode driving system which is not subject to jamming. 
   It is another object of the present invention to provide a welding electrode driving system which is efficient in operation. 
   It is yet another object of the present invention to provide a welding electrode driving system which may be easily disassembled for maintenance or components replacement purposes. 
   It is still another object of the present invention to provide a welding electrode driving system which is relative simple in construction and cost effective in fabrication. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective top elevation view of the welding device having the welding electrode driving system according to the present invention. 
       FIG. 2  is a partially sectional perspective side elevation view of the enclosure of the welding device with the slidable carriage mounting rod. 
       FIG. 3  is a perspective top elevation view of  FIG. 2  showing the crank shafts. 
       FIG. 4  is a partial sectional side elevation view of the left slidable carriage of the welding electrode driving system according to the present invention. 
       FIG. 5  is a partial sectional top elevation of the left slidable carriage with the rotatable crank shaft mounted thereon. 
       FIG. 6  is an perspective front end view of the enclosure of the welding device shown in  FIG. 2 . 
       FIG. 7  is a perspective front end view of the welding device as shown in  FIG. 4 . 
       FIG. 8  is a sectional view along section line VIII—VIII of  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to the drawings wherein like reference numerals designate corresponding parts in the several views, a welding device  10  having a electrode driving system according to the present invention is best shown in  FIG. 1 . The welding electrode  11  is a continuous welding electrode having a welding flux coating formed on the outer surface of a metal core  12 . The flux coating has short flux sections  13  evenly spaced from neighboring sections by gaps  14  of an equal distance. Such continuous welding electrode  11  enables the welding operation to be carried out in a continuous manner to provide a high quality weld having a smooth surface. Two slidable carriages, namely a left slidable carriage  15  and a right slidable carriage  16  are slidably mounted to the enclosure  17  by two upper mounting bolts  18  and  19 , and two lower mounting bolts  20  and  21  respectively as best shown in  FIGS. 1 ,  2 ,  3  and  6 . The left slidable carriage  15  and the right slidable carriage  16  are identical in construction but having different lengths; namely, in the example shown, the left slidable carriage  15  is longer than the right slidable carriage  16  by one flux section  13  plus one gap  14 . The construction of the left slidable carriage  15  is shown in  FIGS. 4 ,  5 ,  7  and  8  and described herein in detail. The slidable carriage has a main body portion  22  having an upper ball bearing sleeve  23  and a lower ball bearing sleeve  24  located on the outer left side of the main body portion  22  and extending horizontally and parallel to one another. The mounting bolts  18  and  21  are inserted through the upper ball bearing sleeve  23  and lower ball bearing sleeve  24  for slidably mounting the slidable carriage to the enclosure  17  of the welding device  10 . An elongated casing  25  extends outwardly and forwardly from the middle of the front edge of the main body portion  22 . The elongated casing  25  has a generally C-shaped cross sectional shape as best shown in  FIG. 6 . The main body portion  22  has two parallel rearwardly extending side walls  26  and  27  with a rotatable crank shaft  28  rotatably mounted thereto. The rotatable crank shaft  28  has a drive shaft  29  and an offset rotary shaft  30 . The mounting between the offset rotary shaft  30  and the side wall  27  is such that the rotational movement of the offset rotary shaft  30  will transform into a linear reciprocating movement of the main body portion  22  relative to the mounting bolts  18  and  21 . 
   A drive housing  31  is located at the rear of the enclosure  17  a drive crank shaft  32  is rotatably mounted in the drive housing  31  and it is coupled to a speed controlling gear box  33  which is, in turn, coupled to the driving gear  34  rotatable by an electric motor (not shown). Coupling rods  35  and  36  are linked between the rotatable crank shaft  28  and the drive crank shaft  32 , so that rotation of the drive crank shaft  32  by the stepping motor will cause the offset crank shaft  30  to rotate accordingly for imparting the reciprocating motion of the main body portion  22 . In the meantime, the stepping motor will also initiate a drive wheel  37  mounted horizontally on the opposite side of the main body portion  22  as shown in  FIG. 4 . The rotation of the drive wheel  37  will cause two cam wheels  38  and  39  to rotate in the same direction. Two pivotal arms  40  and  41  are pivotally mounted in a cantilever manner on the main body portion  22 . These pivotal arms  40  and  41  are pivotable relative to the mounting pins  42  and  43  respectively and they are normally maintained in a horizontal position parallel to one another by two tension springs  44  and  45  respectively mounted between the pivotal arms  40  and  41  and the main body portion  22 . At the normal position, abutment pins  46  and  47  provided on the pivotal arms  40  and  41  are in contact engagement with the periphery edge of the cam wheels  38  and  39  and the free end portion of the pivotal arms  40  and  41  abut two slider pins  48  and  49  slidably mounted on the main body portion  22 . Two elongated rotatable bars  50  and  51  are rotatably mounted in the elongated casing  25  in a mutually parallel manner by support bearings  52 ,  53 ,  54  and  55 . Three gripping plates  56 ,  57  and  58 , and  59 ,  60  and  61  are mounted on the rotatable bars  50  and  51  respectively as shown in  FIGS. 4 ,  5  and  7  adjacent to the support bearings  52 ,  53 ,  54  and  55 . The gripping plates  56 ,  57  and  58  are reinforced by support blocks  62 ,  63  and  64 , the gripping plates  59 ,  60 , and  61  are reinforced by support blocks  65 ,  66  and  67  respectively. 
   Two pivotal rods  68  and  69  are respectively mounted on the rotatable bars  50  and  51  adjacent to the end support bearing  52 , and torsion springs  70  and  71  are mounted between the pivotal rods  68  and  69  and the rotatable bars  50  and  51  respectively. The pivotal rods  68  and  69  abut the slider pins  48  and  49 . When the slider pins  48  and  49  are pushed inwards by the pivotal arms  40  and  41 , the slider pins  48  and  49  will push the pivotal rods  68  and  69  respectively to turn the rotatable bars  50  and  51  accordingly. The turning of the rotatable bars  50  and  51  will, in turn, turn the gripping plates  56  and  59 ,  57  and  60 , and  58  and  61  away from one another to an open position. Continue rotation of the cam wheels  38  and  39  will subsequently return the pivotal arms  40  and  41  to the parallel horizontal positions to release the pushing force on the slider pins  48  and  49 , therefore the tension springs  44  and  45  and the torsion springs  70  and  71  will turn the rotatable bars  50  and  51  back to the original position. The gripping plates  56  and  59 ,  57  and  60 , and  58  and  61  will accordingly return to a closed position adjacent to one another as shown in  FIG. 7 . At the closed position, the gripping plates will grip the metal core of the welding electrode through its gaps  14 , while at the open position, the gripping plates will release its grip on the welding electrode to allow it to advance forward. The gripping plates will be at the closed position when the left slidable carriage  15  is in the forward moving stage in its reciprocating motion so that the welding electrode  11  is advanced forward by the left slidable carriage  15 . 
   As shown in  FIG. 1  the right slidable carriage  16  is identical in construction and operation to the left slidable carriage  15  but are 180 degrees out of phase with one another; namely the left slidable carriage  15  is one flux section  13  plus one gap  14  longer than the right slidable carriage  16  such that gripping plates of the left slidable carriage  15  and right slidable carriage  16  are located at alternate gaps  14  of the welding electrode  11 . Thus, the gripping plates on the right slidable carriage  16  are at the open position when the right slidable carriage  16  is in the return moving stage while the left slidable carriage  15  is at the forward moving stage with the gripping plates in the closed position, so that the welding electrode  11  is advanced forward by the left slidable carriage  15 ; and when the right slidable carriage  16  is in the forward moving stage with its gripping plates located in the closed position, the left slidable carriage  15  will be in the rearward moving stage with its gripping plates at the open position, so that the welding electrode is advanced forward by the right slidable carriage  16 . In this manner, the welding electrode  11  is continuously advanced alternately by the left slidable carriage  15  and the right slidable carriage  16  by their reciprocating movement. 
   While this invention is susceptible of embodiment in different forms, the drawings and the specification illustrate preferred embodiments of the invention, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention, and the disclosure is not intended to limit the invention to the particular embodiments described.