Effect of the integrated treatment on the manufacturing of printing cylinders

Abstract

We have developed a comprehensive technology to strengthen printing cylinders by forming a regular microrelief at the surface followed by chromium-plating. Our research into the influence of comprehensive machining of a printing cylinder on the quality of printed products has established the mechanism for obtaining high quality parameters for the working surface of printing cylinders. Application of vibratory tool with a radius of R=2 mm, at effort P=550 N, the surface roughness amounted to the arithmetic mean deviation Ra 0.63 µm, which is 7.6 times lower than that without applying the surface-plastic deformation. A comprehensive machining of a printing cylinder includes a combination of the vibration knurling with the formation of the all-new regular microrelief followed by chromium-plating. Vibration knurling was performed at a tool indentation effort of 50‒600 N; a spindle rotation frequency of 25‒2,000 rpm; a deformative tool eccentricity of 0.2‒1.0 mm; a deformative tool frequency of oscillations of 1,000‒2,000 double step per minutes; a deformative tool feed of 0.08‒12.5 mm/rev. The chromium-plating involved the electrolyte CrO 3 ≈290 g/l and H 2 SO 4 ≈3 g/l; the electrolyte temperature was 57 °C; duration of chromium was 20 min; a current density was 80 A/dm2, time activation was 20 s. As a result of this, it became possible to obtain the developed surface of the cylinder with high operational characteristics. Our experimental research has confirmed that the machining modes significantly change surface roughness, hardness, and microhardness. This reinforces the surface strengthening of the printing cylinder. In particular, it was found that the integrated technology contributed to a 1.2‒1.6-time increase in hardness compared to the base metal hardness, and a 2.7‒3.3-time increase compared with chromium-plated surface. That makes it possible to argue on that the revealed formation mechanism matches the predefined properties. Thus, there is reason to assert that it is possible to prolong the service life of printing cylinders, to ensure stable operation of the equipment, to improve the quality of printed products owing to the application of the integrated technology followed by chromium-plating.