Analysis of the double longitudinal spanning avera

Analysis of Double Longitudinal spanning average beam of asphalt paver

Abstract This paper probes into the benchmark of automatic leveling of paver, compares the advantages and disadvantages of different formed average beams, makes a detailed analysis of the principle of spanning average beam, and points out the application prospect in combination with the actual situation of road construction in our country at present

key words: paver automatic leveling of spanning average beam road flatness

1 overview

at present, asphalt pavers with high technology are equipped with a set of corresponding automatic leveling system. The application of this system is the most effective way to improve road flatness. Correctly configuring, adjusting and using this system is the key to whether the automatic leveling system of paver can achieve the best effect

pavers with large operation width are equipped with two longitudinal and one horizontal automatic leveling controllers, which can realize three configuration methods: single longitudinal, one longitudinal and one horizontal, and double longitudinal, so as to adapt to different construction conditions. The single longitudinal configuration method is most commonly used to deal with longitudinal joints when paving in multiple widths; The method of one vertical and one horizontal is convenient and effective when the paving width is small (generally less than 6m). When the paving width is large (generally greater than 8m), the double longitudinal method can only be used. However, no matter which method is adopted, the longitudinal controller used to control the elevation and thickness direction error (flatness) is essential, and the use of the longitudinal controller must have an accurate and reliable benchmark. The longitudinal datum is also the reference line of the whole leveling system. Its setting and use is the guarantee of whether the whole leveling system can play its role to the greatest extent. Using the moving average beam as the benchmark is an advanced process method at present

2 basic principle of average beam

average beam has two categories: shovel type and spring floating type. Its basic principle is that the error amplitude value of the foundation height direction within the average beam length range is multi-level mathematical averaging and filtering through the geometric relationship (articulated) or mechanical relationship (spring floating), which reduces the amplitude, so that in the movement process of the paver, the motion track at the midpoint of the leveling beam becomes a transition smooth curve, and the absolute value of the curve amplitude is very small, It is within the allowable error range of the whole control system and serves as the reference standard of the automatic leveling instrument. It can be seen that the average beam is the benchmark installed on the body of the asphalt paver and moves forward randomly. Although it runs on the subgrade with large errors at the same time as the paver, it can produce an independent benchmark. This method is very suitable for road construction. It is not affected by the inherent longitudinal and transverse slopes of the road, and is not limited by the length of the road

the shovel connected average beam is then sent to the computer for data processing. The structural diagram is shown in Figure 1 (a), which generates an ideal reference point through pure geometric relations. In the figure, points a, B, C, D, e, F, G and H are the contact points between the average beam and the ground, and points K, m, N and P are the secondary hinge points, which are located at the midpoint of AB, CD, EF and GH; R. Point q is the third hinge point, which is located at the midpoint of KM and NP; Point O is the error detection point, and the position is set at the midpoint of TQ. The position shown in the figure is on the ideal ground. At this time, the heights of the second stage hinge and the third stage hinge are H1 and H2

figure a

if point a first encounters a high area during driving, the position is raised e, as shown in Figure 1 (b), at this time, because a rotates around B, d around m, R around Q, the points a, K, R move up relative to the original position, The positions of each point are:

△ ha=he △ hk= △ ha/2=he/2

△ hr= △ hk/2=he/4

△ ho= △ hr/2=he/2

this indicates that when an error occurs on the ground, the change of o point is 1/8 of this value. This can be used as the reference point of the leveling system. Theoretically, the more the number of stages of the average beam is, the more it automatically returns to the initial experiment after the experiment is completed, and the more the positions of the experimental force time curve, the experimental force, the peak value, and the yield force with obvious yield characteristics are displayed, the smaller the displacement change of the detection point is. Theoretically, the N-level average beam can obtain the reference line of 1/2n error. However, due to the limitations of the actual structure and use requirements, it can only be achieved at Level 3 or 4

figure b

because the accuracy of the articulated average beam is limited by the number of stages, and because of the structural limitations, it is easy to interfere with the horizontal and vertical straight tie rods of large pavers, so the average beam of this structure is less used in large pavers

another spring floating average beam. The average beam diagram of this structure is shown in Figure 2, which generates an ideal reference point through pure mechanical relations

figure 2

in the figure, a beam with weight g advances under the support of N springs with elastic coefficient K. When the ground is a horizontal plane, the elastic force of each spring is g/n, and the compression amount is s. according to Hooke's theorem:

s · k=g/n

s=g. (n · K)

during driving, a spring encounters a high area he, the beam changes from the original position h to the new position H1, the position of the beam is raised s>e, and the spring encounters a high area is further compressed, The compression amount becomes:

s1=s+he se

the elastic force generated by it becomes

f2=k · (s+he SE)

the compression amount of other springs decreases se, Each generated elastic force becomes

s1=k · (s-se

because g=f1 · (n-12) + f2

, it can be obtained that

gt= (n-1) · K · (s-sfont size= "1">e+k · (s+he SE)

g=ns-nse+he

combined with s=g/(n · K), it can be obtained that