Header with flexible cutter bar assembly

A header for use in a field to harvest agricultural crops, the header comprising:

• a header frame with a front portion and a rear portion, each extending laterally between opposite ends;
• and
• a cutter bar assembly coupled to the header frame, the cutter bar assembly flexible upwardly and downwardly relative to the header frame along a generally vertical plane between the opposite ends of the header frame for contouring to the field, the cutter bar assembly including
• a guard bar extending laterally across the front portion of the header frame between the opposite ends thereof, the guard bar split into at least a first lateral section and a second lateral section at a guard bar joint,
• wherein the first lateral section is operatively coupled to the second lateral section at the guard bar joint to horizontally align the first and second lateral sections of the guard bar between the opposite ends of the header frame while allowing relative lateral movement therebetween during upward and downward flexing of the cutter bar assembly,
• a reciprocating sickle bar slidably mounted to and extending longitudinally across the guard bar,
• a plurality of knife guards fixedly secured to the guard bar and intersecting with the sickle bar for cutting the crops to be harvested as the sickle bar reciprocates longitudinally between the opposite ends of the header frame,
• wherein the first and second lateral sections of the guard bar each terminate at an opposing inner edge adjacent to the guard bar joint, the inner edges defining a gap therebetween for allowing the first and second lateral sections of the guard bar to move laterally relative to each other during flexing of the cutter bar assembly, and
• wherein one of the first and second lateral sections includes upper and lower alignment elements extending laterally across the gap between the first and second lateral sections of the guard bar.