The influence of incrustation and chute blockage on the dynamic behaviour of a bucket wheel excavator slewing superstructure

Abstract

Exploitation of bucket wheel excavators (BWEs) is accompanied by an increase of mass due to transport and adherence of a large amount of the material. Technical regulations do not account for the dynamic behaviour of BWEs. Such problems are analysed as quasi-static. A procedure and results of investigation of the influence of masses of the bucket wheel (BW) incrustation and soil in a blocked BW chute on the superstructure response are presented. Analysis of sensitivity of dynamic characteristics and the response to adherence of the material is conducted. The method and results can be used in the design stages of new and in reconstructions of obsolete BWEs.

Analysis of the Dynamic Response as a Basis for the Efficient Protection of Large Structure Health Using Controllable Frequency-Controlled Drives

“…, 64), created for the BWE SchRs 1600 (Figure 2). The procedure for the formation and validation of the model, which has already been successfully used to analyze the impacts of the number of buckets [56], the counterweight mass [57], as well as incrustation and chute blockage [58] on the dynamic response of the structure, is described in detail in [59].…”

“…A study on the impact of the bucket-wheel frequency of revolution, i.e., the frequency of revolution of the bucket-wheel drive electromotor (FREM), on the dynamic response of the referent points of the structure, determined in accordance with the standard [52], was conducted using a spatial reduced dynamic model of the slewing superstructure with 64 degrees of freedom (generalized coordinates qs, s = 1, 2, …, 64), created for the BWE SchRs 1600 (Figure 2). The procedure for the formation and validation of the model, which has already been successfully used to analyze the impacts of the number of buckets [56], the counterweight mass [57], as well as incrustation and chute blockage [58] on the dynamic response of the structure, is described in detail in [59]. was formed by applying the Lagrange's second-order equations, A system of differential equations of motion (vibrations) of the model under the action of the excitation caused by the resistance to excavation,…”

Tie-rods of the bucket wheel excavator slewing superstructure: A study of the eye plate stress state

“…Results of the modal analysis conducted for the continuously-varying parameter κ of the adhered material (κ = 0-no soiling; κ = 1-100% soiling) [50] show that the values of all of the 14 analysed SS dynamic model's natural frequencies decrease as the mass of the adhered material increases, Fig. 15 and Table 8.…”

Bucket wheel excavators: Dynamic response as a criterion for validation of the total number of buckets

“…It is worth mentioning that, in practice, the mass of the material in the BW chute leading to a halt in the excavation process is always somewhat lower than the maximum calculation mass of the material inside the volume of the BW chute [49]. However, certain load cases in the current standards and regulations (for example load case HZS4.4 prescribed by the code [49]) call for the inclusion of the maximum calculation mass [50]. Therefore, in order to fully assess the impact of the material in the BW chute on the natural frequencies and the dynamic response of the SS while remaining compliant with the mentioned load case, its mass in the model (κm BWC ) has been varied over the range from m BWC,min = 0 (empty BW chute, κ = 0) to m BWC,max = m BWC = 61 t, corresponding to the case of a completely blocked BW chute (completely filled BW chute, κ = 1).…”

“…Therefore, in order to fully assess the impact of the material in the BW chute on the natural frequencies and the dynamic response of the SS while remaining compliant with the mentioned load case, its mass in the model (κm BWC ) has been varied over the range from m BWC,min = 0 (empty BW chute, κ = 0) to m BWC,max = m BWC = 61 t, corresponding to the case of a completely blocked BW chute (completely filled BW chute, κ = 1). Masses of the material incrusted on the BW (m BWI ≈ 20 t) and the material in the completely blocked BW chute (m BWCB ≈ 61 t) are now taken into account, allowing for the inclusion of the operating conditions with sufficient accuracy, as presented in [50]. However, unlike strength calculations, negative dynamic effects may occur for any of the considered masses of the system, not just the maximum mass.…”