1 Introduction
   The modernized numerical control transformation of the original heavy-duty horizontal lathes and roll lathes is a shortcut with less investment, quick results and remarkable results. The heavy-duty horizontal lathes and roll lathes required by the user's factory for CNC transformation are applicable to the high-efficiency heavy-duty cutting of rough and fine processing of the rolls of ordinary steel, forged steel, alloy cast iron, high-speed steel and Gaoming steel. It can complete high-precision, low-roughness and high-efficiency automatic cutting of outer circle, inner hole, end face, tapered surface, internal and external thread, arc and various curved composite holes f. At present, Tangshan Heavy Machine Tool Plant has successfully carried out numerical control and modernization of the ordinary heavy-duty horizontal lathes C61125A, C61160 and C61200G, which are the largest metallurgical roll manufacturing enterprises in China, and achieved good economic benefits.
2 Comparison of main parameters and performance of common type and new CNC type heavy horizontal lathe (roller lathe) (see Table 1)
Table 1
   Take the C 61 20 0 common type and the new CNC heavy duty horizontal lathe as an example.
   From the comparison in Table 1, we can see:
   (1) The main parameters of the common type and the new CNC type heavy-duty horizontal lathe and roll lathe, and the main drive speed range (the first seven items in Table 1) are basically the same.
   (2) Range of vertical and horizontal feed: common type: narrow feed range, and has step-variable shifting, complete feed movement and turning thread movement, relying on main drive, feed box, light bar, screw, slip A plurality of sets of shifting mechanisms such as a crate and a tool holder are linked together to realize. To complete fast movements, a special fast motor drive is required, and the speed is half that of a CNC machine.
   New CNC type: wide feed range, stepless speed change, can be adjusted as needed, all kinds of feed machining movements are separate transmissions, each movement axis has its own AC servo drive motor, mechanical speed reduction system, combined with the spindle The configured rotary position encoder performs the combined feed motion of the main shaft, the longitudinal Z-axis and the lateral X-axis under the unified control of the numerical control system. The fast moving speed is twice that of the normal type, which means that the movement efficiency of the empty stroke is increased by 2 times and the auxiliary preparation time is shortened by half.
   (3) Principle of cutting processing (for example, the complex hole type on metallurgical roll is taken as an example): Ordinary type: All kinds of forming tools are needed for machining to find the workpiece hole to be machined by the various types of forming tools. Processing, low efficiency and poor precision. The processing arc curve curve size, contour accuracy is unstable, low efficiency, it is difficult to adapt to the requirements of variable hole type.
   New CNC type: The X-axis, 2-axis interpolation linkage and spindle S speed are automatically changed by CNC program during machining, which drives the indexable cutter head to complete the machining of any hole curve in the plane coordinate system with high precision and high precision. Any change in the hole type can be adapted by changing the machining program.
   From the above analysis and comparison, it can be seen that the numerical control transformation of ordinary heavy-duty horizontal lathes or roll lathes mainly focuses on the improvement of the main transmission part, such as the injection and the modernization of the vertical and horizontal feed parts.
3 CNC transformation design content
   The original light bar and the lead screw are removed from the bed, the guide rail is reground, and the high-precision helical rack is mounted in the longitudinal direction.
   The main drive spindle and gear system are optimized, the encoder is installed at the rear of the spindle, and the speed control system is updated to an advanced all-digital DC speed control or AC variable frequency speed control system.
The vertical and horizontal feed system abolishes the tool holder, the slide box and the feed box of the original machine tool, and redesigns and manufactures a set of CNC tool holders, slide boxes, frame type table holders (or multi-station turret table holders).
3.1 The numerical control tool holder is composed of a horizontal carriage and a horizontal feed transmission chain of the tool holder carriage, and the large carriage is moved on the vertical guide rail of the bed. The plastic guide rail pair and automatic lubrication are used to reduce the friction coefficient. The transverse drive chain is driven by the AC servo motor to reduce the speed gear, and the ball screw (nut) sub-tool holder lateral slide to complete the lateral (X-axis) feed motion.
3.2 CNC slide box It is the key transmission component of longitudinal ultra-long-distance high-precision feed movement. For heavy-duty moving parts with a moving distance of more than 6m, the feed movement with positioning accuracy is especially important. The large longitudinal (Z-axis) feed motion is driven by an AC servo motor and uses a double pinion anti-backlash transmission. The internal use of the helical gear spiral principle and the axial movement of the central axis drive the double pinion to rotate relative to the helical rack to achieve the purpose of the backlash transmission.
The longitudinal (Z-axis) and horizontal (X-axis) axes are fed to the feed axis using a precision grating as a position detection feedback element to form a closed loop control.
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