3-gun KL -117 machine for electron beam welding of drill bits

• Machine is intended for electron beam welding of drill bits with diameter up to 17.5" with simultaneous performance of three welds, due to this both accuracy of drill bits dimensions and welding output increase
• Application of a powerful control electronic tube in the accelerating voltage source prevents the arc processes in the welding gun by means of accelerating voltage short interruption, which doesn't lead to failure in the welds formation
• The RASTR system, functioning on the principles of raster electron microscope, provides an opportunity to watch the welding process and automatic coincidence of each of three beams of electrons with the butt joints of groove faces in the real time mode. The clear picture of the welding process is displayed on the monitor screen and is not exposed to the welded metal vapors, which is characteristic for traditional optical observing systems.
• Machine is provided with the electrons beam diagnostic system allowing an operator:
  - to define the beam focusing plane position prior to welding;
  - to periodically evaluate changes in space and energy beam parameters in order to define the necessity of the welding gun cathode replacement.
• Lanthanum Hexaboride cathode as a tablet has service life not less than 40 hours in the welding mode at beam power 20 kW, besides the beam axis position doesn't change at changes in beam focusing.
• Control of all equipment subsystems by means of CNC +PLC.
• The computer system of electron beam scanning stabilizes the molten pool state and improves the quality of face and root surfaces formation of the weld.
  

  MACHINE DESIGN AND DATA

Vacuum chamber consists of two sections. Upper chamber has three branch pipes to dispose three guns, equipped with turbo molecular pumps. Lower chamber is equipped with the drill moving mechanism. It has a faceplate with a chuck to assembly three drilling bit legs.

To load/unload the bits, the lower vacuum chamber has the front door displaced aside by means of compressed air. The assembled drill bit is brought to welding area by the table disposed on the left of the lower chamber. The welded bit is unloaded from the chamber by another table disposed on the right of the lower chamber.

CONTROL SYSTEM REVIEW

Machine Control System is based on the principles of open architecture. It comprises the upper and lower level computers connected via the Ethernet and provides the following opportunities:

• A single button control of the whole bit welding process, including pumping out of the vacuum system and filling in air to the chamber.rotary gun axes and 2 rotary rotator axes);
• The programmed change in beam current, focusing current, welding velocity in the function of bit moving with regard to the welding guns.
• Automatic and semi-automatic welding according to any of the programs stored in the programs library.
• Manual control of vertical bit moving and its pivot turn rotation.
• The vacuum system control by an operator's commands given in semi-automatic and manual modes.
• Based upon the operating system Widows NT an operator's interface providing an opportunity to specify and correct the welding programs as diagrams or tables for any drill bit profile. No special skills are required in programming, an operator in fact teaches the control system for welding of each of the bits standard dimensions using the accumulated results of welding mode selections.
• Integration of several subprograms into one master program for welding of each of the bits dimensions.
• Simultaneous automatic search of each of the three butt joints both in the preliminary system teaching mode and in the welding process in the real time mode by means of electromagnetic beams deflection using the RASTR system. The probable welding deformations do not lead to beams deflections from the butt joints plane.
• Analysis by means of the RASTR system of the bit assembly quality with giving command for welding prohibition in case of inadmissible displacement of the butt joints trajectory.
• Execution of a bit repair welding by one gun.
• Documentation, printing of the welding results as a passport, saving of all control commands and the used welding programs as tables and diagrams within two months.
• Diagnostics of subsystems state. Remote control and diagnostics via the Internet.
  

  Main technical parameters