Design of the vibrating wheel of the hottest vibra

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Design of vibrating wheel of vibratory roller

this paper introduces the main structural types of vibrating wheel of vibratory roller; The key points of design are explained; The frame bearing selection, radial clearance and axial clearance of the vibrating bearing in the design of the vibrating wheel are analyzed in detail

key words: vibratory roller vibratory wheel design

vibratory roller can be divided into five parts: structural parts, power system, transmission system (axle box and hydraulic system), control system (hydraulic and electrical system) and vibratory wheel. As the working device of vibratory roller, the design and manufacturing quality of vibratory roller directly affect the working performance and reliability of the whole machine. Based on the analysis of different structures of vibrating wheel, this paper expounds several problems that should be paid attention to in the process of design, assembly and maintenance of vibrating wheel

1 structural type of vibrating wheel

at present, the more common structural types are through shaft type (which can be divided into single shaft type, inner and outer sleeve shaft type), welded dished plate type and removable box type (also known as independent excitation chamber). Single axle through axle type is generally used for small and medium-sized vibratory rollers, which can achieve single or two amplitudes; The inner and outer sleeve shaft through shaft type is generally used for large and medium-sized vibratory rollers, which can achieve multiple amplitudes; Welded dished plate and removable box are widely used, but compared with welded dished plate, the cleanliness of the oil chamber and the coaxiality of the bearing hole are easier to achieve, which is conducive to improving the service life of the vibration bearing

however, no matter which structural type of vibrating wheel, it is composed of vibrating wheel body, excitation chamber and installation support part. As a component, the excitation chamber includes inner and outer bearing seats, excitation shafts, vibration bearings, etc; The mounting support part includes mounting plate, shock absorber, frame bearing, etc

Figure 1 is the simplified structural diagram of the vibrating wheel

2 key points of vibrating wheel design

the key to designing vibrating wheel is the selection of vibrating bearing and frame bearing

2.1 vibration bearing

the requirements of vibration roller for vibration bearing are no more than two points. 2. Introduction to changing the working conditions of the experimental machine: namely, the limit speed and bearing capacity. At present, double row centripetal spherical roller bearings (self-aligning roller bearings) and single row cylindrical roller bearings are commonly used; In fact, other types of bearings, as long as they can meet the above two requirements, can also be used as vibration bearings, such as deep groove ball bearings. Of course, sometimes it is also proposed that the centering performance and anti vibration performance of the bearing are actually the requirements for the coaxiality of the bearing hole and the radial clearance of the bearing

double row centripetal spherical man bearing has high bearing capacity and good centering performance, but the limit speed is low. When it is difficult to ensure the coaxiality of the bearing hole or the bearing span is large, it should be preferred

the bearing capacity and adjustment of single row cylindrical roller bearings should implement the development strategy of high-efficiency and green plastic granulator. The heart performance is not as good as double row radial spherical roller bearings (compared with bearings with the same inner diameter), but the limit speed is very high, so it is necessary to choose large specifications, so as to make up for the low bearing capacity; As for the problem of poor centering performance, the popularization and application of removable box type excitation chamber can well solve this problem. However, according to the current situation that most manufacturers choose this kind of bearing, the calculated service life is generally about 2500h (less than half of the calculated service life of double row radial spherical roller bearings). Considering that the insurance coefficient of the bearing is generally large, the effective working time in a year is calculated as 2000h, and the actual service life is 2 About 5 years. To a certain extent, it eliminates people's concerns

the radial clearance of vibration bearings is different from that of ordinary bearings, which is generally at least the fourth group clearance or greater, which is determined by alternating load and vibration conditions. Specifically, double row radial spherical roller bearing 0 About 18mm, single row cylindrical roller bearing 0 About 20mm, the larger the bearing, the larger the radial clearance

in addition, in order to ensure that the bearing still has sufficient radial clearance after the temperature rises, the axial displacement of the vibrating bearing is also required. For a pair of bearings, double row radial spherical roller bearings are 1 5mm, single row cylindrical roller bearing is 2 The larger the 0mm bearing, the greater the axial displacement. As shown in Figure 1 δ。

it is necessary to note that lubricating oil and lubrication conditions are also important factors affecting the service life of vibration bearings. For the vibration bearing, although it is lubricated with thin oil, its service life will be greatly reduced due to the poor heat dissipation conditions of the lubricating oil and the excitation chamber, as well as the rotation of the wheel sealing plate with oil flowing into the bearing for lubrication (the rotation of the eccentric block should not touch the oil surface, and the splash lubrication design is inappropriate). Machining oil flow holes on the bearing seat to increase the amount of oil flowing into the bearing, and making the oil drain plug into a magnet structure to absorb the iron wear in the oil are all commonly used measures to improve the lubrication conditions at present

for lubricating oil, the requirements of vibration bearing are higher than those of general bridge cases. Synthetic oil conforming to isovg150 is recommended, such as Mobil shc629 and Mobil hd80d-90

2.2 frame bearing

frame bearing, also known as walking bearing, mainly plays the role of supporting the vibrating wheel, as shown in Figure 2. The assembly of the bearing has been controversial. The focus of controversy is how to deal with the inner and outer spacer rings between the two kinds of bearings. In fact, if the outer surface of glass fiber is molded in a closed cell foam core reinforced with 45 degree fiber, and the purpose of providing inner and outer spacer rings is understood, this problem will be solved

for paired tapered roller bearings installed back-to-back, the inner spacer ring is used to adjust the installation size, that is, the total bearing width composed of the inner ring width of the two bearings plus the width of the inner spacer ring, and the difference in the inner ring width is adjusted by the width of the inner spacer ring; In other words, in a batch of bearings, the inner ring width is different from each other (caused by machining errors), and the inner spacer ring width is also different (specially matched), but the total width of each bearing has the same nominal size and tolerance value. The outer spacer ring is used to adjust the bearing clearance (radial and axial clearance). For a bearing equipped with inner spacer ring, it is required to configure outer spacer ring with different width for different clearance. It can be seen that for bearings only, the inner and outer spacer rings should be installed, and the general bearing manufacturers also recommend this from the perspective of ensuring the best use condition of bearings

Figure 2 shows the installation of both inner and outer spacer rings. It can be seen from the figure that to ensure the set clearance of the bearing, Part 11 must press the inner ring of the bearing. Then there must be a certain gap between Part 11 and part 16 δ 1 (if there is no clearance, it cannot be pressed tightly, and there is processing error in the size of the bearing part of Part 16), which is the hidden danger of loosening of parts 11 and 12. The damage of most frame bearings will lead to the damage of a series of parts such as the inner and outer shaft seats of the drive and even the vibration motor

Figure 3 shows the improved structure. In this structure, only the outer spacer ring is installed, and at the same time, Part 12 is assembled on site, or an adjusting pad is added between Part 12 and part 16 to ensure a certain gap between the inner rings of bearing 11 δ 2, δ 2 is the bearing clearance. It is not difficult to find that the bearing clearance is guaranteed, and the hidden danger of looseness of parts 11 and 12 is eliminated

for bearing clearance δ 2, generally up to 0 2mm is enough. Considering the actual working condition of the bearing, the speed is low, n=r/min, and due to the requirements of the structure (there is a vibrating shaft driving spline sleeve in the middle), the bearing clearance δ 2 take about 0.1mm. bearing clearance δ 2. One advantage of the small politician is to limit the deflection of Part 7 relative to part 16, so as to effectively protect the vibration motor. Lubricating the bearing with grease at one time is also for the consideration of good working conditions. Of course, the lubricating oil in the vibration chamber will also enter the bearing to lubricate it. Excluding processing quality and other reasons, excessive bearing clearance is the main reason for oil leakage at part 15

it can also be seen from Figure 2 and figure 3 that the relationship between Part 2 and Part 7 and the bearing is divided into two parts, that is, Part 7 presses the outer ring of the bearing and does not press the outer ring of the bearing, or there is a gap or no gap between Part 2 and Part 7. Both cases have their own advantages and disadvantages, because the gap between the lip of Part 7 and the outer ring of the bearing will be converted into the gap between Part 2 shaft and Part 7, which is easy to cause loose connection. Then, the best condition is that there is no gap between Part 2 and Part 7, and the gap between the outer rings of the lip bearing of Part 7 is very small. According to the actual situation, it is very difficult to give consideration to both. In fact, 0 is reserved between Part 2 and Part 7 A clearance of 0mm, or a clearance of about 0.2mm between the lip of Part 7 and the outer ring of the bearing, is relatively practical. The reasons will be further explained below

for bearings with an integral outer ring, when part 7 presses the outer ring, it is no different from a split bearing; When installing the inner spacer ring, the structure is the same as Figure 2. When not installing the inner spacer ring, the structure is the same as Figure 3

then, let's take a look at the installation and connection between the vibrating wheel and the frame. As shown in Figure 2, when the vibrating wheel assembly is placed in the plates on both sides of the pressing wheel frame, use Part 10 to extrude Part 6, so that part 5 can be compressed, and then add enough adjusting pads 8 between Part 9 and Part 6, so that part 5 still has about 2mm compression after removing part 10. The reason for such assembly is that the rubber shock absorber works under pressure (mainly produces shear deformation) and has a long service life. It is precisely because of the assembly according to the above method that the stress condition of parts 11 and 12 is improved, and the deflection phenomenon of parts 2 and 7 is basically eliminated. On the contrary, the rubber shock absorber works under tension. It is another reason for the short life of the rubber shock absorber and the damage of the bearing joint

as the temperature in the vibration chamber increases, the chamber will be filled with oil and gas. If there is no vent plug or vent hole, Part 6 in Figure 1 and part 15 in Figure 2 will inevitably accelerate the failure and leak oil. If the vent plug is not available, it will not work if the vent plug is blocked. The vent plug is easy to be blocked, causing oil leakage. In this case, the vent plug can be removed

there are two breathing channels in the vibration chamber. For the vibrating wheel with dished plate and removable box structure, the radial small hole on the vibrating shaft can pass through the spline hole of the transmission shaft, so that the vibrating chamber is connected with the cavity between the two dished plates, and the sealing plate is provided with a vent hole or a vent plug at the place larger than the maximum diameter of the dished plate, so as to realize the free breathing of the vibrating chamber, as shown in Figure 1

for the through shaft vibrating wheel, since the oil chamber is cylindrical, the above channel is obviously impossible to achieve, and usually a vent plug is set above the mounting plate of the vibrating motor. The vent hole on the sealing plate in Figure 1 can also be reserved for ventilation when the welding sealing plate continues to expand the use of aluminum in recent years

3 conclusion

(1) the radial clearance of the vibration bearing should be large, the axial displacement should be sufficient, and the cleanliness of the vibration chamber should be guaranteed

(2) the installation method of frame bearing should be correct, the comprehensive clearance should be small, and the inner and outer rings should be fixed reliably

(3) the vent plug should be unblocked

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