Discussion on several works that should be paid at

2022-08-13
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Brief discussion on several works that should be paid attention to before paving operation

please pay attention to the following matters when widening the screed:

(1) first prepare several hard skids of appropriate size, with the size of 80 × eighty × 480mm is appropriate, and the quantity should meet the installation needs: at least 3 pieces are padded under the basic screed; Except for the 0.25m lengthened section, two pieces are padded under each lengthened screed

(2) stretch or mechanically widen the screed to the required working width, and you can add extension joints alternately left and right, but you should try to make the width of the left and right screed equal to maintain the force balance of the screed

(3) the total width of the screed after widening should be slightly less than the paving width by 20~30cm, so that the paver can operate

(4) there is a 60 ° clockwise phase difference between the tamper shafts of the left and right basic screed, which has been adjusted at the factory; The phase difference of 90 ° clockwise shall be maintained between the tamper shafts on each two extension sections

(5) the vibrator phase on the basic screed and the extended screed of the mechanical widening screed must be the same; The phase of the vibrator on the telescopic screed and the extended screed of the hydraulic telescopic screed must be the same. In order to ensure the consistency of phase, the simplest way is to reduce the eccentric mass of the vibrator of the basic screed and the extended screed to the lowest position when installing the coupling. At this time, the maximum exciting force will be generated

and be familiar with the equipment structure, button function and operating system you want to operate

(6) when paving the road with large thickness and width, due to the great paving resistance, in order to prevent the screed from deforming backward, you should generally assist the side tensioning mechanism to tighten the screed forward during work, so as to ensure the paving quality and prevent possible damage to the screed

(7) pay attention to adjusting the gap between the front baffle scraper and the front ram head ε。 It can be adjusted by tensioner and ejector bolt. The clearance between the ram and the ram baffle shall be 0.3~0.5mm. Such as gap ε If it is too large, asphalt mortar will be bonded between the front baffle and the rammer and will accumulate seriously; If the gap is too small or there is no gap, it will cause excessive wear on the front end of the punch and wear-resistant insert. At the same time, due to excessive resistance, the rammer cannot reach full speed immediately when paving the mixture, resulting in the reduction of paving compactness when starting up

2 lengthening of spiral auger

pay attention to the following matters when installing the screw:

(1) when assembling the spiral blade, pay attention to check whether the contact surface with the shaft or shaft sleeve is smooth and clean, because any accumulation on the surface may cause the deformation of the blade during assembly and fastening, resulting in the fracture of the hardened spiral blade

(2) according to the requirements of safety rules, the extended auger should be protected at its front end and top, so after the screw is assembled, the baffle with corresponding length should be installed, and the protective fence should be inserted into the hole of the baffle to cover the whole auger channel. First, cut off the power supply to form a single inlet and outlet distribution channel - paving trough

(3) if the working conditions do not require the lengthening of the auger on the full width of the screed, the lengthening joint of the spiral blade with larger diameter can be selected to speed up the conveying of materials

3 adjustment of screed camber

it is generally necessary to set the camber of the screed of the paver before paving the full width road. Place the screed on the ground, adjust the horizontal brace, and then lift the screed. Measure the camber of the screed along the full width with a thin line, so that the camber value is equal to the design value + 1/the commercial grade polyethylene is 1.50 ⑵ 00600~1/500

4 adjustment of the initial elevation angle of the screed

for the screed with a certain structure, under a certain paving state, that is, under different paving speed, vibration frequency, amplitude, material type, material temperature, paving thickness, there is an elevation angle of the screed α。 The initial elevation of the screed should be adjusted before each paving

lower the screed to the required paving thickness and put it on the base plate, whose thickness is equal to the surface elevation of the loose paving layer at the starting point of paving. If the base course at the starting point of paving has reached its design elevation, the surface elevation h of the loose paving layer is:

H = y * r + J

y is the compaction thickness, R is the loose paving coefficient, j is the design elevation of the base course

if the base course at the starting point of paving does not reach its design elevation, the surface elevation h of the loose paving layer is equal to:

H = (q? JS) * r + JS

q is the design elevation of the paving layer at the starting point of paving, JS is the measured elevation of the base course at this place

the loose paving coefficient r should be determined after trial paving, and it can be preliminarily determined according to experience before trial paving

under normal conditions, the setting size of the initial elevation is as follows:

a) the paving thickness is less than 10cm, and the scale value is about 0

b) the paving thickness is 10~20cm, and the scale value is about 0.5

c) the paving thickness is more than 20cm, and the scale value is about 1.0~2.5

manually control the lifting and lowering of the regulating oil cylinder in front of the paver to adjust the height of the traction point so that the traction boom is basically horizontal. At this time, the height pointer of the adjusting cylinder is roughly equal to the paving thickness value

when adjusting the elevation angle, attention should be paid to:

(1) when adjusting the elevation angle of the screed, the left and right must be adjusted in coordination, and the final adjustment scale value of the left and right should be the same, otherwise the screed will be damaged by torsion

(2) there is no precise adjustment value for the size of the elevation angle. The above data is only for reference. The reason is that the paving temperature, short service life of material fixtures, hydraulic leakage and other problems occur one after another, which has a great impact on the actual paving results. Therefore, before paving, trial paving should be carried out to adjust

(3) when adjusting the height position of the traction point, attention should be paid to the coordination between the left and right, and the height difference between the two sides should not be greater than 7.5cm, otherwise the screed will be damaged

(4) for the tire paver, because the dynamic radius of the tire is slightly larger than the static radius, and the tire compression after the hopper receives the material, the elevation of the screed will be reduced, making the paving layer thinner when starting the paving, and the required paving thickness can be achieved only after automatic leveling and climbing adjustment. Therefore, when adjusting the screed elevation angle of the tire paver, it is necessary to correct the elevation angle. A compensation value should be added according to experience, which is generally about 0.2 °. The compensation value is slightly higher when the material temperature is high, and slightly lower when the material temperature is low

(5) for hydraulic telescopic screed, the height difference between the telescopic screed and the basic screed should be adjusted at the same time as the elevation angle. After the initial elevation adjustment, the elevation of the back edge of the telescopic screed and the back edge of the basic screed shall reach the surface elevation of the loose paving layer at their respective positions

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