The use and development of the engraving head of the electronic engraving machine II
1.3 direct acting electromagnet "
the structural principle is shown in Figure 4. The direct acting shaft with the engraving knife is fixed on the armature, and the armature is adjusted during assembly to make it in a relatively balanced state in the magnetic field. When the control coil is not powered on, the gravity of the 4.5.1 hardness magnetic steel cannot make the armature act; When the control coil is powered on, the armature produces polarity. Under the action of electromagnetic force, it overcomes the stiffness of the armature and moves a certain displacement. Apply high-frequency voltage or current to the control coil, and the armature will move up and down, so as to drive the vertical movement of the engraving knife, and complete the work of engraving pits on the plate roller of the lower plate lifting system of the friction pair
in this structure, the movement of the armature is translational, and the two sides of the air gap are synonymous magnetic poles; The high stiffness return spring is obtained by the elastic deformation of the armature
some foreign companies adopt this structural principle, which can also reach a very high frequency. The electromagnet of this structure has complex structure and large volume, so it is difficult to assemble and debug. In terms of electronic and mechanical engraving, the engraving frequency of the engraving head of hell company has developed from 4000Hz at first to 12800hz now, and the vision3 engraving head of MDC company has reached 8100hz, which can reach 8600hz when the hole depth is slightly reduced, which improves the production efficiency. Electronic engraving has the advantages of variable depth and area of the engraving hole, strong repeatability, and no pollution in the engraving process
3. After confirming that the power supply is under the specified voltage and grounded safely, 2 laser engraving and electron beam engraving
2.1 laser engraving "
in the 1970s, laser began to play a role in the field of offset printing and gravure plate making. In the 1990s, foreign companies began the research of laser direct engraving. Laser direct engraving lateral loading system engraving copper plate has always been considered technically infeasible, but it can directly engrave zinc. Swiss MDC company realizes laser direct engraving through the improvement of plate making process. First, a thin layer of nickel was plated on the steel roll, then copper was plated on its surface, and then a layer of zinc was plated. This layer of zinc can absorb laser energy and evaporate, followed by the evaporation of copper under it, forming ink carrying holes. After engraving, like other engraving rollers, the roller is finally plated with a layer of hard chromium. A YAG laser with a power of about 500W has also been developed, which can carve 70000 holes per second
the direct laser engraving system is mainly composed of three parts: high-energy laser; Laser transmission system; The optical system adjusts the energy per unit area by adjusting the focal length. The principle of laser is shown in Figure 5
laser pulse; The diameter of the focus point and the incident energy determine the geometry of the point. A simple direct laser engraving system can only adjust the energy, and the diameter of the laser focus is preset according to the required points, which cannot be changed in the engraving process. The diameter of the point is determined by the diameter of the laser focus
advanced SHC (newsuperhalfauttypialcell) adjustment method makes each laser pulse; The two parameters: energy and the diameter of the focus point can be adjusted. "Advanced" means that the geometry of each point - the diameter of the point and the depth of the point can be adjusted independently to ensure the accuracy of direct laser engraving. Hell solved the technical difficulties of laser direct engraving of copper plate, and showed the developed laser engraving machine prototype that can be directly engraved on copper plate or chromium plate on drupa2004, which has brought great repercussions to the industry
with the development of laser technology, laser engraving not only embodies the advantages of electronic and mechanical engraving, but also has many own advantages, such as non-contact engraving. At present, the cost of making plate rollers by this method is slightly higher, but its many advantages make it a direction of engraving development
(to be continued)