Investigation of the influence of the degree of non-sinusoidal mold oscillation of the law on the formation of a hard crust of billets
A decisive influence on the formation of crusts and
the amount of friction in reciprocating motion of the mold have a frequency and amplitude of oscillation. Mold oscillation amplitude influences the distance between the tracks, and the frequency - in their depth of penetration. However, these two parameters are not sufficient to optimize the length of time independently of movement along the workpiece with the mold and return it upwards. Studies on the effect of the mold oscillation on the surface quality of continuously cast billets was conducted under the CCM PJSC "Enakievo Steel." The main purpose of the work is to evaluate the surface quality of continuously cast billets, spilled with sinusoidal and triangular modes of oscillation of the mold. The experiments have been tried various settings of the mold oscillation in obtaining billets section 150x150 mm steel St5 (Table 5.2) and selected in the same mold (of 4) of the sites with the most characteristic pieces surface conditions. Table 5.2 - Parameters studied casting blanks
Photos of the most characteristic signs of oscillation occurring on the surface of the workpiece, for the studied samples are shown in Figure 5.24. For quantitative estimates of the profile (relief) surface platen using a dial gauge IC-10 (class - 1, graduation - 0.01 mm). For studies of surface roughness profile LED mounted in a magnetic rack, which was attached to a stationary milling machine. Then, on the machine frame is rigidly fixed platen (Figure 5.25). Measurements carried along through every inch platen surface by moving bed milling machine. Starting point of the surface should be zero, subsequent the deviation above or below zero.
Figure 5.24 - Photo two sides adjacent faces templet study: 1, 2, 3, 4 - room platen, A and B - side platen
Visual inspection of the selected platen revealed that traces of the mold oscillation are most noticeable in the middle platen. In addition to approximately 10 mm from the corner uzhimin noticeable presence that can not be associated with the regime of the swing. Uzhimin width of 15-20 mm. Therefore, the definition of the workpiece surface roughness for the plane made a small radius (A) and side (B) along lines parallel platen corner located at a distance of 10 mm (line ab Figure 5.26) and 28 mm (line cd figure 5.26).
Figure 5.25 - Installation for measuring roughness of the surface profile cast billets: 1 - bed milling machine, 2 - platen billets, 3 Indicator 4 - magnetic stand
Figure 5.26 - Diagram of the selection of pieces platen In addition, we measured the profile most distinct traces of rocking angle platen to its middle on the side of "A" at a different distance from the start of platen. The results of the measurements are shown in Figures 5.27 and 5.28. Found that for platen № 4, selected from the blank with an amplitude sweep spilled 4.8 mm, oscillation frequency 205 / min and 0.7 Wave form is characterized by the most smooth surface profile with a penetration depth of 0.6-0.7 mm rocking tracks. Platen for number 1 and number 2, selected from billets poured using electromechanical and hydraulic tilting mechanism and providing back-and-forth motion of the mold sinusoidally, the surface of the
workpiece is more pronounced raised bumps with a penetration depth of traces rocking 1.68 mm and 1, 6 mm, respectively. Platen for number 3 (with Wave form 0.6) penetration rocking tracks takes an intermediate value, and is 1.0-1.1 mm. Obtained during the measurement data correspond well with the results of metallographic studies (Figure 5.29): the depth of penetration traces tilting platen surface layer of the workpiece, cast using sinusoidal oscillation is about 0.22-0.25 mm, triangular - 0.17 -0.18 mm, ie, 25-30% less. Summarizing the results, it should be noted that the use of non-sinusoidal oscillation mode of the mold gives less severe signs of swinging on the surface of the workpiece and reduce the depth of penetration of the track rocking body blank about 30%. Together with the ability to change the swing of the mold itself in the process of casting it makes the use of hydraulic rotary actuators mold preferred.
Figure 5.28 - The distribution irregularities of the surface profile in the wake of the swing
Figure 5.29 - Depth of penetration rocking tracks on samples cast of sinusoidally a), b) and triangular), d) the laws (increasing x150)