Built-in stepless indexing ram for gantry type CNC (Computerized Numerical Control) boring and milling machine

The utility model discloses a built-in stepless indexing ram for gantry type CNC (Computerized Numerical Control) boring and milling machine. A main motor and a speed reducing mechanism are arranged on the upper part in a ram body; the built-in stepless indexing ram is characterized in that a main shaft, which is used for transmitting power to an accessory head, is supported by a main shaft front bearing and a main shaft rear bearing and arranged in a C shaft sleeve; the front half part of the C shaft sleeve is arranged on a supporting body by a C shaft support rear bearing and a C shaft support front bearing; the supporting body is fixedly arranged in the ram body; the rear end of the C shaft sleeve is connected with inner and outer spline sleeves by an inner spline sleeve; a gear-engaging poison and an oil cylinder body are arranged at the peripheries of the inner and outer spline sleeves; the oil cylinder body contacts with the inner wall of the ram body; a C shaft band-type brake is fixedly arranged on the inner wall at the front end of the supporting body; a steel grating scale is fixedly arranged on a large-diameter table at the periphery at the front end of the C shaft sleeve by a steel grating supporting body; a measuring scale head is fixedly arranged on an opposite position of the ram body; a positioning end-toothed disc is arranged at the inner edge at the front end of the C shaft sleeve; and four pulling claws are arranged on the front end surface of the C shaft sleeve. The ram device shortens the main transmission length of a machine tool, so that the any-angle indexing positioning of the C shaft is realized; and the angle position of the C shaft can be directly detected by a detecting element at the front end of the main shaft.