Large hydraulic cone crushers are widely used in mining fields. When the crusher is installed on-site, it is essential to ensure the meshing of the bevel gear pair of its main transmission components.
To ensure the design requirements and installation accuracy and reduce the difficulty of on-site installation, the trial assembly and inspection are repeated many times before leaving the factory to meet the meshing requirements of the gear pair. Although the trial installation in the factory ensures the quality of the on-site installation of the crusher, it increases the production cycle and cost of the enterprise.
Chamol‘s team researched the backlash adjustment and assembly of bevel gears based on the lead pressing method. The research showed that, based on the approximate relationship between the axial adjustment amount of the bevel gear and the expected backlash, the thickness of the adjusting washer was calculated to ensure the assembly accuracy of the high bevel gear. , and improve its transmission efficiency.
By deviating the center line of the bevel gear of the cone crusher from the center line of the eccentric sleeve by A/2 (A is the gap between the eccentric shaft sleeve and the frame bushing), we conclude: when the gear pair usually operates, due to the A/2 offset, the centerline of the bevel gear is the centerline of the frame, to ensure that the apex of the bevel gear coincides with the apex of the pinion gear to achieve a normal gear meshing relationship.
By measuring the size chain and calculating the repairing ring during bevel gear assembly, we propose adjusting the meshing clearance of bevel gears by using the method of assembly and fitting.
Although many researchers have proposed different methods to ensure the backlash of the bevel gear pair during the assembly process, due to different working conditions and the improvement of installation accuracy, the backlash of the gear pair meshing is required to be more precise.
Through the practice and exploration of the in-factory trial assembly of the large hydraulic cone crusher produced by CITIC Heavy Industries, Chamol proposed a method of assembling the bevel gear pair of the giant crusher in place at one time, which realized the final assembly of the large hydraulic cone crusher without in-factory. Thus The production cost is reduced, and the production cycle is improved.
Influencing factors and research methods
Bevel gear assembly structure and influencing factors
The transmission mode of the hydraulic cone crusher is to transmit force and torque through the meshing between the bevel ring gear and pinion gear. Therefore, ensuring good contact between the tooth surfaces of the large and small bevel gears and accurate meshing of the gear pairs is the key to the smooth and safe operation of the crusher.
The structure of the hydraulic cone crusher is shown in Figure 1. Through the structural analysis of the transmission part, it is found that two main factors cause the multiple trial installation of the bevel gear pair of the crusher:
- The dimensional error of processing and manufacturing is superimposed during assembly, and the influence of accumulated error on the actual meshing position of the large and small gear pairs;
- Effect of actual backlash adjustment on the pinion installation position.
Therefore, controlling and adjusting the dimensional error superposition of manufacturing and the actual backlash is essential in ensuring the accurate installation of the bevel ring and pinion gear.
Principles and methods
To understand the impact of the dimensional error of the crusher manufacturing on the meshing position of the large and small bevel gears, Chamol’s team collected and analyzed the assembly data of the relevant parts of the cone crusher.
By measuring the actual processing dimensions of the relevant parts and comparing them with the theoretical dimensions, the relevant position dimensions of the bevel gear pair are calculated, as listed in Table 1. Due to processing and manufacturing, the accumulated dimensional error of the ring gear and pinion gear is obtained to be determined during the assembly process. The measured error needs to be controlled.
|Bevel Ring Gear||Underlying rack bevel ring gear location dimension|
Bevel ring gear centre hight+mounting thickness-thrust bearing thickness
|Pinion Gear||Underlying rack pinion gear location dimension|
Pinion gear centre hight+mounting thickness-thrust bearing thickness
In addition, if we want to understand the impact of the adjustment of the actual teeth side clearance on the installation position of the pinion gear, we need to consider the drawing requirements, design and installation requirements and ensure that the gear contact area is biased towards the small end of the pinion gear.
Therefore, according to the variation of the backlash, it is necessary to increase the axial movement of the pinion gear installation
Δ t = Δj n / (N tgαsinθ 2),
In the formula: Δj n is the backlash variation of the gear, mm; N is the coefficient; α is the pressure angle of the pinion gear, (°); θ 2 is the pitch angle of the pinion gear, (°).
In summary, the method calculates that the measured error and the axial movement of the pinion gear installation need to be controlled during the assembly process, and the tooth side clearance of the bevel gear pair meshing is adjusted during the installation process so that the tooth side clearance meets the design requirements. Realize the purpose of bevel gear pair assembled in place at one time.
Measurement results and analysis
Influence of machining on the meshing of gear pair
Limited to the level of industrial manufacturing (bevel gear production process) and processing accuracy, there are processing errors in the actual manufacturing of ring gear and pinion gear and related components, and the accumulation of processing errors will affect the actual meshing position of the gear pair during the installation process.
Therefore, before installation, it is necessary to measure the relevant dimensions that can affect the gear pair’s meshing, obtain the actual measurement error caused by the accumulation of processing, and adjust the padding.
The meshing relationship of the bevel gear pair is shown in Fig. 2. Analyze the structure of the transmission part of the crusher, and measure the relevant dimensions that can affect the meshing of the bevel gear pair before installation. Measure the dimensions L1 and L2 from the meshing angle center of the ring gear and pinion gear to the gear installation end face, respectively; measure the thrust bearing size B according to the assembly relationship of the crusher ring gear, and measure the thrust bearing installation end face of the central shaft center hole of the lower frame of the crusher to The measured dimension D of the center of the auxiliary shaft hole, and the measured dimension C of the installation thickness of the ring gear mounting seat. After installing the Ring gear, the deviation dimension H1 between the actual meshing center and the academic meshing center
H1= (B + D – C) – L1.
The assembly relationship of the transmission part is shown in Figure 3. Measure the actual dimension E from the installation end face of the auxiliary shaft hole transmission shell of the lower frame of the crusher to the center of the central shaft hole. After the components of the transmission, parts are assembled. All inspections are qualified indirectly by measuring the inner retaining ring’s left end face at the transmission shell’s left end. The same dimension F of the left end of the large flange. When installing, hot-fit the pinion gear to the drive shaft of the transmission part and make it close to the left end face of the inner retaining ring at the left end. After the Pinion gear is installed, the deviation between the actual meshing center and the theoretical meshing center
H2 = (F + L2) – E.
If it is considered that the meshing center of the ring gear is higher (or lower), the theoretical need to add cushion thickness
H = H2±H1 tanθ1,
The formula: θ 1 is the pitch angle of the ring gear (°).
Since ring gear and pinion gear are displacement processing (negative displacement of ring gear, positive displacement of pinion gear), the difference between the cumulative change of the actual installation position of the ring gear in the dimensional chain and the displacement coefficient is too significant.
Therefore, in the actual installation process, the influence of the deviation value of the meshing center of the ring gear on the installation may not be considered. After tracking and measuring the crusher series products, the cumulative error of crusher processing is obtained, as listed in Table 2.
Effect of assembly on the meshing of gear pair
In addition to the influence caused by the accumulation of machining errors, the actual installation process of the ring gear and pinion gear will also change the meshing position of the gear pair due to the influence of assembly errors.
After the ring gear and pinion gear are installed on the lower frame of the crusher and the gear handle of the transmission case is at the level, first add pads according to the theoretical padding thickness value, fix the ring gear, and then measure and check and record the gap between the ring gear and pinion gear Backlash should be measured at the tightest point of engagement.
Compare the measured tooth backlash with the ideal value required by design at this time to determine the amount of backlash variation of the gear
Δj n = jn desired – jn measured.
At this time, push out the transmission housing slightly, replace the thickness of the pad with H + Δt, tighten the transmission housing again, fix the ring gear, and then use the pressure gauge method to measure, check and re-record the ring gear and pinion Gear backlash, the backlash value should be measured at the tightest point of meshing. Then the actual pad thickness
T = H + Δt.
When the influence of the ring gear meshing center deviation value on installation is not considered, the actual cushioning thickness can be obtained:
T1 = H2 + Δt.
When assembling, perform rounding and padding according to the closest actual padding thickness T. After the padding is completed, adjust and install the transmission part assembly to the sub-shaft hole of the lower frame. The above method tracks and measures the cushioning thickness of the crusher, as listed in Table 3.
|Product NO.||Actual padding thickness|
Effect and adjustment of teeth backlash on gear pair mesh
The actual meshing tooth backlash of the ring gear and pinion gear cannot be directly measured. It needs to be calculated by indirectly measuring the movement of the crusher coupling and connecting rod and using a dial indicator to detect the moving distance of the connecting rod. The actual meshing tooth backlash
In the formula: jt is the backlash value on the pitch circle, mm; m is the distance from the position of the dial gauge monitoring point to the center line of the pinion gear, mm; φ is the pitch circle diameter of the pinion gear, mm.
Since the transmission housing is installed eccentrically, the backlash of the gear can be adjusted by rotating the transmission housing. To make the backlash value meet the design requirements, it needs to be completed by adjusting the gear handle of the transmission case. Loosen the connecting bolts between the transmission housing and the lower frame; adjust the gear handle clockwise, and the side clearance increases; adjust the gear handle counterclockwise, and the side clearance decreases. After adjustment, connect the connecting bolts and measure the side clearance again until the side clearance meets the design requirements. The actual contact effect of the Pinion gear is shown in Figure 4.
Through the research on the adjustment method of the bevel gear pair of the cone crusher, the formula for the actual pad thickness when the transmission part is installed is introduced. In the production and application of large cone crushers, the bevel gear pair of the crusher is assembled in place at one time, and the gear meshing side clearance, contact position, and contact ratio all meet the design requirements, reducing the assembly workload and improving production efficiency. This research method provides theoretical support for adjusting bevel gear pairs of large gyratory crushers.