An improved sliding bearing gearbox low temperature end face seal test rotating system
By introducing a rigid high-speed mechanical spindle and a flexible metal coupling into the low-temperature end-face sealing test system for sliding bearing gearboxes, and combining vibration sensor monitoring and adjustment, the problems of large vibration and lack of coaxiality reference at low temperatures were solved, and reliable high-speed operation of the low-temperature end-face seal was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING AEROSPACE PROPULSION INST
- Filing Date
- 2023-07-27
- Publication Date
- 2026-07-07
AI Technical Summary
In the existing technology, the low-temperature end face sealing test system for sliding bearing gearboxes has a large vibration value at low temperature, which leads to excessive leakage and makes it impossible to assess the end face sealing. In addition, there is no reference for coaxiality adjustment, which affects the reliability of the test.
The rotor components are connected by a rigid high-speed mechanical spindle and a flexible metal coupling. The coaxiality is monitored and adjusted by a vibration sensor to ensure that the coaxiality of the sliding bearing gearbox and the test device is accurately adjusted, thereby reducing vibration and dry friction.
It effectively solved the problem of coaxiality adjustment between the sliding bearing gearbox and the test device, reduced vibration, avoided end face seal leakage, and improved the high-speed operation reliability and service life of the low-temperature end face seal.
Smart Images
Figure CN116952467B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of cryogenic testing technology for liquid rocket engines, and relates to an improved rotating system for cryogenic end-face sealing testing of sliding bearing gearboxes. Background Technology
[0002] Cryogenic end-face seals are crucial components in liquid rocket engine turbopumps, requiring cryogenic medium verification tests before engine assembly. Cryogenic end-face seals operate at high speeds (not less than 20,000 r / min) and low temperatures (-196℃). At low temperatures, the mechanical properties of the materials change, leading to increasingly harsh operating conditions. Therefore, cryogenic end-face seal tests place extremely high demands on the dynamic performance of the rotating system. Currently, cryogenic end-face test systems using sliding bearings to support the high-speed end shaft are quite common.
[0003] The gearbox is supported by hydrodynamic sliding bearings. The working principle of these bearings is based on the movement of the journal relative to the bearing bush during high-speed rotation. Lubricant is drawn into the wedge-shaped gap of the bearing by the journal to form a pressure film. The smaller the oil film gap and the higher the relative rotational speed, the greater the dynamic pressure and the stronger the bearing's load-bearing capacity. During high-speed operation, the high-speed shaft and bearing bush automatically center, with the journal close to the center of the bearing bush. However, during operation, the offset of the shaft center will vary depending on the external load and operating conditions such as rotational speed, thus limiting the rotational accuracy and stability.
[0004] When this gearbox was used to test the low-temperature end face sealing assembly, the vibration value was large, and the leakage was prone to exceed the standard during the test, making it impossible to achieve the purpose of evaluating the end face sealing.
[0005] The above phenomenon is mainly due to the gap between the bearing bush and the shaft of the hydrodynamic sliding bearing. The position of the main shaft is easily affected by external interference. After rotation, the position is easily changed, which will lead to two problems: (1) There is no reference for coaxiality adjustment, and it is impossible to achieve accurate adjustment of the coaxiality between the high-speed shaft of the gearbox and the main shaft of the test device. If there is a large error in the initial coaxiality, it will cause excessive vibration of the system during the test; (2) During high-speed operation, the sliding bearing is easily affected by external disturbances, which will cause the shaft center running trajectory to change, which will cause the end face seal and the dynamic ring to change the state of the fit, and the oil film thickness to change. In severe cases, it can lead to dry friction. Summary of the Invention
[0006] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose an improved rotating system for low-temperature end face sealing test of sliding bearing gearbox, so as to solve the problems of no reference for coaxiality adjustment of sliding bearing gearbox and test device and excessive vibration during test, thereby ensuring the reliability of high-speed operation test of low-temperature end face sealing.
[0007] The solution of the present invention is:
[0008] An improved rotating system for testing the low-temperature end-face seal of a sliding bearing gearbox includes a high-speed gearbox, a metal flexible coupling, a high-speed mechanical spindle, a low-temperature flexible coupling, and an end-face seal testing device.
[0009] The high-speed shaft of the high-speed gearbox is connected to the input shaft of the high-speed mechanical spindle via a metal flexible coupling. The output shaft of the high-speed mechanical spindle is connected to the spindle of the end-face sealing test device via a low-temperature flexible coupling. The high-speed gearbox rotates at high speed, thereby driving the metal flexible coupling, the high-speed mechanical spindle, the low-temperature flexible coupling, and the end-face sealing test device to rotate synchronously.
[0010] A vibration displacement sensor X1 and a vibration velocity sensor V1 are installed at the high-speed shaft head of the high-speed gearbox to monitor the vibration of the high-speed shaft during operation. A vibration displacement sensor X2 and a vibration velocity sensor V2 are installed at the middle position of the metal flexible coupling to monitor the vibration of the metal flexible coupling during operation. A vibration displacement sensor X3 and a vibration velocity sensor V3 are installed at the shaft head of the input end of the high-speed mechanical spindle to monitor the vibration of the end where the high-speed mechanical spindle connects to the metal coupling.
[0011] A vibration displacement sensor X4 and a vibration velocity sensor V4 are installed at the output end of the high-speed mechanical spindle to monitor the vibration at the connection end between the high-speed mechanical spindle and the metal coupling.
[0012] Preferably, the high-speed shaft bearing of the high-speed gearbox is a sliding bearing with an operating speed of 20,000 r / min to 40,000 r / min.
[0013] Preferably, the high-speed shaft of the high-speed gearbox has the following characteristics under static conditions: (1) When the oil pump is not turned on to supply oil to the high-speed gearbox, the center position of the high-speed shaft will change after each rotation. According to actual testing, the vertical position of the high-speed shaft changes by about 0.1mm after one rotation; (2) After the oil pump is turned on to supply oil to the high-speed gearbox and high-speed rotation is performed, as the speed increases, the high-speed shaft will gradually float in the bearing and eventually be located at an skewed position at the center of the bearing.
[0014] Preferably, the high-speed mechanical spindle includes a mechanical shaft, a front bearing, a bushing, a rear bearing, a bearing housing, a gasket, a clamping cover plate, and a base. The bearing housing is mounted on the base, and the front bearing, bushing, and rear bearing are sequentially fitted onto the mechanical shaft. The front bearing and the rear bearing are respectively installed in the corresponding bearing holes of the bearing housing. The gasket is placed on the outer ring end face of the rear bearing, and the clamping cover plate clamps the gasket and fixes it on the bearing housing.
[0015] Preferably, the front and rear bearings are identical in model and specifications, both using EAG grease-lubricated angular contact ball bearings with a limiting operating speed of 60,000 r / min, and the front and rear bearings are installed back-to-back.
[0016] The preferred design method for high-speed mechanical spindles is as follows:
[0017] (1) By idling the high-speed gearbox, obtain the vibration displacement value of the high-speed shaft head of the high-speed gearbox after the high-speed gearbox reaches thermal equilibrium, as well as the rise in center height x1 when the initial temperature reaches temperature equilibrium.
[0018] (2) Select the front bearing, bushing, and rear bearing, and design the overall structure of the high-speed mechanical spindle. Calculate the total frictional torque M and the bearing frictional power loss P based on the size, specifications, and preload of the selected bearings.
[0019] (3) Determine whether the total frictional torque M of the bearing and the frictional power loss of the bearing meet the requirements. If yes, proceed to step (4); if no, return to step (2) to reselect the front bearing, bushing and rear bearing and design the overall structure of the high-speed mechanical spindle.
[0020] (4) Establish a thermodynamic simulation calculation model for the high-speed mechanical spindle, analyze the increase in center height x2 caused by bearing friction heat generation after reaching thermal equilibrium, and perform a difference analysis with the increase in center height x1 when the high-speed gearbox reaches temperature equilibrium. If |x1-x2|≤0.02mm, the high-speed mechanical spindle design is considered qualified; otherwise, return to redesign the high-speed mechanical spindle until |x1-x2|≤0.02mm.
[0021] Preferably, in step (2), the total frictional torque M of the bearing satisfies
[0022] M = M0 + M1
[0023] Where: M0—bearing hydrodynamic loss;
[0024] M1 — Frictional loss caused by elastic hysteresis and differential sliding of the contact surface;
[0025] Preferably, the thermodynamic simulation calculation model of the high-speed mechanical spindle is set up as follows:
[0026] 1) A heat source is placed on the surfaces of the two bearing balls and the inner and outer rings, and the heat generation is set to P. 发热 ;
[0027] 2) The initial temperature of the high-speed mechanical spindle and the environment is set to 25℃;
[0028] 3) The convective heat transfer coefficient between the outer surface of the high-speed mechanical spindle and the environment is set to 5 W / m.2 ·℃;
[0029] 4) Set the coefficient of linear expansion and thermal conductivity of the bearing material and the high-speed machine spindle material;
[0030] Simulation calculations yielded the increase in center height x2 of the high-speed mechanical spindle.
[0031] Preferably, the high-speed mechanical spindle should also be coupled with the high-speed shaft of the high-speed gearbox, the metal flexible coupling, the low-temperature flexible coupling 4, and the spindle of the end face sealing test device to perform a three-span rotor dynamics simulation calculation to check whether its first-order critical speed meets the working speed requirements. The bearing support stiffness should be taken as the lower limit of the bearing support stiffness range. If the requirements are met, the high-speed mechanical shaft design is considered qualified; otherwise, the high-speed mechanical shaft should be redesigned.
[0032] Preferably, the debugging method for the high-speed mechanical spindle is as follows:
[0033] S1 adjusts the coaxiality of the high-speed gearbox and the high-speed mechanical spindle;
[0034] S2 obtains the coaxiality center deviation h1 and left and right deviation k1 between the high-speed gearbox and the high-speed mechanical spindle;
[0035] S3 operates at high speed, connecting the high-speed mechanical spindle to the high-speed shaft of the high-speed gearbox via a metal flexible coupling. The high-speed mechanical spindle is driven by the high-speed gearbox, and the values of vibration displacement measuring points X1, X2, X3, X4, vibration velocity measuring points V1, V2, V3, V4, and vibration acceleration value a of the high-speed mechanical shaft bearing housing are recorded.
[0036] S4 keeps the left and right deviation k1 of the coaxiality between the high-speed gearbox and the high-speed mechanical spindle constant, and adjusts the center height deviation between the high-speed gearbox and the high-speed mechanical spindle sequentially through h1+0.01, h1+0.02, h1+0.03, h1+0.04, h1+0.05, h1+0.06, h1+0.07, h1+0.08, h1+0.09, h1+0.10. Under each center height deviation, high-speed operation is carried out, and the values of vibration displacement measuring points X1, X2, X3, X4, vibration velocity measuring points V1, V2, V3, V4, and vibration acceleration value a of the high-speed mechanical shaft bearing seat are recorded.
[0037] S5 When a set of vibration data X1, X2, X3, X4, V1, V2, V3, V4, and a is at its minimum value, it is considered that the coaxiality of the center height of the high-speed gearbox and the high-speed mechanical spindle corresponding to this set of vibration data is the best. At this time, the dynamic characteristics of the double-span rotor composed of the high-speed shaft of the gearbox and the high-speed mechanical spindle are the best and it is not easily affected by external excitation. Record the center height deviation value h corresponding to this set of vibration data.
[0038] S6 keeps the center height deviation value h constant, and adjusts the left and right deviations of the high-speed gearbox and the high-speed mechanical spindle sequentially through k1 = -0.05, -0.04, -0.03, -0.02, -0.01, 0, 0.01, 0.02, 0.03, 0.04, 0.05 mm. Under each left and right deviation, high-speed operation is carried out, and the values of vibration displacement measuring points X1, X2, X3, X4, vibration velocity measuring points V1, V2, V3, V4, and vibration acceleration value a of the high-speed mechanical shaft bearing seat are recorded. When a certain set of vibration data X1, X2, X3, X4, V1, V2, V3, V4, and a are at their minimum values, it is considered that the coaxiality of the left and right deviations of the high-speed gearbox and the high-speed mechanical spindle 3 corresponding to this set of vibration data is the best. At this time, the dynamic characteristics of the double-span rotor composed of the high-speed shaft of the gearbox and the high-speed mechanical spindle are the best and it is not easily affected by external excitation interference. Record the left and right deviation value k corresponding to this set of vibration data.
[0039] S7 adjusts the coaxiality of the high-speed gearbox and the high-speed mechanical spindle according to the center height and left and right deviations h and k obtained above. After the adjustment is completed, fix the high-speed mechanical spindle base and complete the debugging.
[0040] The advantages of this invention compared to the prior art are:
[0041] (1) The present invention adds a rigid high-speed mechanical spindle between the sliding bearing gearbox and the test device, and uses a metal flexible coupling to connect each rotor component, which effectively solves the problem of no reference for the original direct connection between the sliding bearing gearbox and the test device for coaxial adjustment. After the first coaxiality adjustment of the high-speed mechanical spindle and the gearbox is completed, the high-speed mechanical spindle is set to fixed, which greatly improves the efficiency of coaxiality work.
[0042] (2) The present invention adds a rigid high-speed mechanical spindle between the sliding bearing gearbox and the test device. Through continuous testing and adjustment, the coaxiality error between the high-speed shaft of the gearbox and the mechanical shaft is adjusted to the minimum, so that the gearbox and the mechanical shaft work in the best state, avoiding dry friction between the end face seal and the moving ring, and solving the problems of excessive vibration of the connecting shaft system between the sliding bearing gearbox and the test device and excessive leakage of the end face seal during high-speed operation test of normal products.
[0043] (3) The advantage of the present invention is that if the test device malfunctions or is not in good working condition during the test, resulting in excessive vibration, most of the vibration energy will be absorbed by the high-speed mechanical spindle structure, thereby allowing the gearbox to bear a smaller additional vibration load, thus improving the service life of the gearbox. Attached Figure Description
[0044] Figure 1 This is a schematic diagram of the rotating system structure of the present invention;
[0045] Figure 2 This is a schematic diagram of a high-speed mechanical spindle structure.
[0046] Figure 3 Design process for high-speed mechanical spindles;
[0047] Figure 4 It features a high-speed three-span rotor structure;
[0048] Figure 5 This is a schematic diagram showing the coaxiality adjustment between the gearbox and the high-speed mechanical spindle.
[0049] Figure 6 This is a schematic diagram of the high-speed mechanical spindle debugging process.
[0050] Figure 7 The following is a flowchart of the debugging process for an example. Detailed Implementation
[0051] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0052] To address the problems of existing technologies, this invention provides an improved rotating system for low-temperature end-face sealing tests of sliding bearing gearboxes, which improves the combined rotation performance of the sliding bearing gearbox and the testing device, and enhances the reliability of high-speed operation tests for low-temperature end-face sealing.
[0053] The improved sliding bearing gearbox low-temperature end face sealing test rotating system structure is as follows: Figure 1 As shown, its main components include a high-speed gearbox 1, a metal flexible coupling 2, a high-speed mechanical spindle 3, a low-temperature flexible coupling 4, and an end-face sealing test device 5.
[0054] The high-speed shaft of the high-speed gearbox 1 is connected to the input shaft of the high-speed mechanical spindle 3 via a metal flexible coupling 2. The output shaft of the high-speed mechanical spindle 3 is connected to the spindle of the test device 5 via a low-temperature flexible coupling 4. The high-speed gearbox 1 rotates at high speed, thereby driving the metal flexible coupling 2, the high-speed mechanical spindle 3, the low-temperature flexible coupling 4, and the end-face sealing test device 5 to rotate synchronously.
[0055] The working principle of the improved high-speed rotation system is as follows: the high-speed gearbox 1 is connected to the high-speed mechanical spindle 3 through the metal flexible coupling 2, and the high-speed mechanical spindle 3 is connected to the test device 5 through the low-temperature flexible coupling 4. The high-speed gearbox 1 rotates at high speed, thereby driving the metal flexible coupling 2, the high-speed mechanical spindle 3, the low-temperature flexible coupling 4, and the end face sealing test device 5 to rotate synchronously.
[0056] A vibration displacement sensor X1 and a vibration velocity sensor V1 are installed at the high-speed shaft end of the high-speed gearbox 1 to monitor the vibration of the high-speed shaft during operation. A vibration displacement sensor X2 and a vibration velocity sensor V2 are installed at the middle position of the flexible metal coupling 2 to monitor the vibration of the flexible metal coupling during operation. A vibration displacement sensor X3 and a vibration velocity sensor V3 are installed at the input end of the high-speed mechanical spindle 3 to monitor the vibration at the connection point between the high-speed mechanical spindle 3 and the metal coupling 2. A vibration displacement sensor X4 and a vibration velocity sensor V4 are installed at the output end of the high-speed mechanical spindle 3 to monitor the vibration at the connection point between the high-speed mechanical spindle 3 and the metal coupling 4.
[0057] The high-speed shaft bearing of the high-speed gearbox 1 adopts a sliding bearing with a maximum output speed of 50,000 r / min and an operating speed between 20,000 r / min and 40,000 r / min. Its static characteristics are as follows: (1) When the oil pump is not turned on to supply oil to the gearbox, the center position of the high-speed shaft of the gearbox will change with each rotation. After actual testing, the vertical position of the shaft changes by about 0.1 mm after one rotation; (2) After the oil pump is turned on to supply oil to the gearbox and high-speed rotation is performed, as the speed increases, the shaft will gradually float in the bearing bush and eventually be located at a skewed position in the center of the bearing bush (high skew and left and right skew).
[0058] The maximum operating speed of the metal flexible coupling 2 is 50,000 r / min, its maximum angular compensation angle is 0.75°, its axial compensation capability is ±1.0 mm, and its weight does not exceed 150 g.
[0059] The high-speed mechanical spindle 3 has the following structural composition: Figure 2 As shown, its main structure includes a mechanical shaft 6, a front bearing 7, a bushing 8, a rear bearing 9, a bearing housing 10, a gasket 11, a clamping cover plate 12, and a base. The front bearing 7 and the rear bearing 9 are identical in model and specifications, both using FAG grease-lubricated angular contact ball bearings with a limit working speed of 60,000 r / min, and are installed back-to-back.
[0060] The high-speed mechanical spindle 3 operates as follows: a bushing 8 is installed between the front and rear bearings 7 and 9 to achieve axial positioning of the two bearings and adjust the bearing span. A shim 11 and a clamping cover plate 12 are used to apply and adjust the bearing preload. After preload adjustment, the radial support stiffness of the bearing is >1.0×10⁸ N / m. The mechanical shaft 6 has connection interfaces at both ends for a metal flexible coupling 2 and a low-temperature flexible coupling 4, thereby achieving high-speed transmission and reducing gearbox vibration.
[0061] The mechanical shaft 6 has a length of 102 mm, a bearing span of 25 mm, and a diameter of 20 mm at the bearing mating point. The high-speed shaft is designed as a rigid shaft. When the bearing support stiffness is 1.0 × 10⁸ N / m, the first critical speed of the shaft system is >100,000 r / min, and its first mode shape is a swing mode (not a bending mode).
[0062] Vibration acceleration measuring point a is set on the bearing housing of the high-speed mechanical spindle 3 to monitor the overall vibration of the high-speed mechanical spindle 3; bearing temperature measuring holes are set on the front and rear bearing housings of the high-speed mechanical spindle 3, bearing temperature measuring point T1 is set on the front bearing housing and bearing temperature measuring point T2 is set on the rear bearing housing to monitor the temperature of the two bearings of the high-speed mechanical spindle 3.
[0063] The overall process of high-speed mechanical spindle design is as follows: Figure 3 As shown.
[0064] The design method of the high-speed mechanical spindle 3 is to first obtain the vibration displacement value X1 of the high-speed shaft head of the high-speed shaft gearbox after the high-speed gearbox reaches thermal equilibrium by idling the high-speed gearbox, as well as the center height rise x1 when the initial temperature reaches temperature equilibrium.
[0065] Then, grease-lubricated bearings 7, 9, and 8 were initially selected, and the overall structure of the high-speed mechanical shaft was preliminarily designed. Based on the size, specifications, and preload of the selected bearings, the total frictional torque M of the bearings was calculated using the following formula.
[0066] The total frictional torque is
[0067] M = M0 + M1
[0068] In the formula: M0 — is related to the bearing type, the viscosity and quantity of the lubricant, and the bearing speed;
[0069] M1 – mainly the friction loss due to elastic hysteresis and differential sliding of the contact surface;
[0070] (1) Calculation of M0
[0071] When vn≥2000
[0072]
[0073] In the formula: D m —Bearing pitch circle diameter;
[0074] n—Bearing operating speed (r / min);
[0075] v—the viscosity of the lubricant at the bearing operating temperature;
[0076] f0 — A coefficient related to bearing type and lubrication method;
[0077] (2) Calculation of M1
[0078] M1=f1P1D m
[0079] Where: f1—a coefficient related to bearing type and load;
[0080] P1—Bearing load (r / min) used to calculate bearing friction torque;
[0081] D m —Bearing pitch circle diameter;
[0082] After calculating the total frictional torque M of the bearing, the power loss of the bearing is calculated using the following formula.
[0083] P = 1.05 × 10 -4 Mn
[0084] In the formula:
[0085] P—Bearing friction power loss, W;
[0086] M—Total bearing friction torque, N.mm;
[0087] n—rotational speed, r / min;
[0088] After completing the bearing friction power calculation, a thermodynamic simulation calculation model of the high-speed mechanical spindle is established to analyze the increase in the center height of the high-speed mechanical spindle caused by bearing friction heat generation after reaching thermal equilibrium, x2.
[0089] The thermodynamic simulation calculation model of the high-speed mechanical shaft is set as follows: (1) A heat source is set on the surface of the two bearing balls and the inner and outer rings, and the heat generation is set to P; (2) The initial temperature of the high-speed mechanical shaft and the environment is set to 25℃; (3) The convective heat transfer coefficient between the outer surface of the high-speed mechanical shaft and the environment is set to 5W / m2.℃; (4) The linear expansion coefficient and thermal conductivity of the bearing material and the high-speed mechanical shaft material are set; (5) The rise value x2 of the center height of the high-speed mechanical shaft is obtained by simulation calculation, and the difference analysis is performed with the rise value x1 of the center height when the gearbox reaches temperature equilibrium. When |x1-x2|≤0.02mm, the high-speed mechanical shaft design is considered qualified; otherwise, the high-speed mechanical shaft design is returned to the design until |x1-x2|≤0.02mm.
[0090] The structure of the high-speed mechanical spindle 3 should also include coupling its mechanical shaft 6 with the high-speed shaft 13 of the high-speed gearbox 1, the metal flexible coupling 2, the low-temperature flexible coupling 4, and the test device rotor 14 for a three-span rotor dynamics simulation calculation. This will verify whether its first-order critical speed meets the requirement of a working speed of 40000 r / min. The structural composition of the three-span rotor is as follows: Figure 4 As shown, the bearing support stiffness should be taken as the lower limit of the bearing support stiffness range.
[0091] After the overall structural design and processing are completed, the high-speed mechanical spindle 3 still needs to be debugged.
[0092] The debugging method of the high-speed mechanical spindle 3 is as follows: (1) First, the coaxiality adjustment of the high-speed gearbox 1 and the high-speed mechanical spindle 3 is carried out. The specific coaxiality adjustment is shown in the figure below. Figure 5 As shown. The positioning disc 15 is installed on the high-speed shaft of the gearbox and fixed thereon; the coaxiality adjustment dial indicator I16 and dial indicator II17 are both installed on the high-speed mechanical spindle 3 through the coaxiality measuring fixture. When performing coaxiality measurement, the high-speed mechanical spindle 3 is rotated so that the dial indicator I16 needle touches the maximum outer circle surface of the positioning disc 15, thereby measuring the center height and left and right offset of the high-speed mechanical spindle 3 and the high-speed shaft 13 of the gearbox; the dial indicator I17 needle touches the end face of the positioning disc 15, thereby measuring the perpendicularity of the end faces of the high-speed mechanical spindle 3 and the high-speed shaft 13 of the gearbox; thus, the coaxiality measurement of the two shafts is achieved. The high-speed gearbox 1 is not connected to the oil pump to ensure that the high-speed shaft 13 of the gearbox is located at the lowest part of the bearing. (2) Through coaxiality measurement and adjustment, the coaxiality center height and left and right deviation of the high-speed gearbox 1 and the high-speed mechanical spindle 3 are initially obtained as h1 and k1, respectively; (3) According to Figure 6As shown, the high-speed mechanical spindle 3 is connected to the high-speed gearbox 1 through the metal flexible coupling 2. The high-speed mechanical spindle 3 is driven by the high-speed gearbox 1. The values of vibration displacement measuring points X1, X2, X3, X4, vibration velocity measuring points V1, V2, V3, V4, and vibration acceleration value a of the high-speed mechanical shaft bearing seat are recorded. (4) The coaxiality is measured and adjusted again according to step (2) to obtain the coaxiality center height and left and right deviations h1+0.01, k1. The high-speed operation is carried out according to step (3). The values of vibration displacement measuring points X1, X2, X3, X4, vibration velocity measuring points V1, V2, V3, V4, and vibration acceleration value a of the high-speed mechanical shaft bearing seat are recorded again. The vibration acceleration value a of the bearing seat; (5) By repeatedly repeating step (4) (with a difference of 0.01, the center height deviation is sequentially traversed through h1, h1+0.01, h1+0.02, h1+0.03, h1+0.04, h1+0.05, h1+0.06, h1+0.07, h1+0.08, h1+0.09, h1+0.10, k1=0 remains unchanged, and a total of 11 data points are measured), and the coaxiality center height deviation and the corresponding vibration data are recorded for comparison. When the collected vibration data X1, X2, X3, X4, V1, V2, V3, V4, a are basically at their minimum values. At this time, it is considered that the center height coaxiality of the high-speed gearbox 1 and the high-speed mechanical spindle 3 is at its best. At this time, the dynamic characteristics of the double-span rotor composed of the high-speed shaft 13 of the gearbox and the mechanical shaft 6 are at their best and are not easily disturbed by external excitation. Record the center height deviation value h at this time; (6) Set the center height deviation value as h, adjust the left and right deviations, and make it traverse k1=-0.05, -0.04, -0.03, -0.02, -0.01, 0, 0.01, 0.02, 0.03, 0.04, 0.05mm in sequence. Under each left and right deviation, carry out high-speed operation and record the values of vibration displacement measuring points X1, X2, X3, X4. Vibration velocity measurement The values of points V1, V2, V3, V4 and the vibration acceleration value a of the high-speed mechanical shaft bearing seat, when the collected vibration data X1, X2, X3, X4, V1, V2, V3, V4, a are basically at their minimum values, it is considered that the coaxiality of the left and right deviations of the high-speed gearbox 1 and the high-speed mechanical main shaft 3 is at its best. At this time, the dynamic characteristics of the double-span rotor composed of the high-speed shaft 13 of the gearbox and the mechanical shaft 6 are optimal and not easily affected by external excitation interference. Record the k value at this time; (7) According to h and k, adjust the coaxiality of the high-speed gearbox 1 and the high-speed mechanical main shaft 3. After the adjustment is completed, fix the base of the high-speed mechanical main shaft 3 and take anti-loosening measures. The overall debugging idea is as follows Figure 7 As shown. In one embodiment, a total of 22 coaxiality adjustments were performed.
[0093] After the initial adjustment of the high-speed mechanical spindle 3, subsequent adjustments only require using the high-speed mechanical spindle 3 as a reference to adjust the coaxiality between the end-face sealing test device 5 and the high-speed mechanical spindle 3. The positioning disc 15 of the coaxiality adjustment fixture can be installed on either the high-speed mechanical spindle 3 or the end-face sealing test device 5.
[0094] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.
Claims
1. An improved rotating system for low-temperature end-face sealing test of a sliding bearing gearbox, characterized in that: Includes a high-speed gearbox (1), a metal flexible coupling (2), a high-speed mechanical spindle (3), a low-temperature flexible coupling (4), and an end-face sealing test device (5). The high-speed shaft of the high-speed gearbox (1) is connected to the input shaft of the high-speed mechanical spindle (3) through the metal flexible coupling (2). The output shaft of the high-speed mechanical spindle (3) is connected to the spindle of the end face sealing test device (5) through the low-temperature flexible coupling (4). The high-speed gearbox (1) rotates at high speed, thereby driving the metal flexible coupling (2), the high-speed mechanical spindle (3), the low-temperature flexible coupling (4), and the end face sealing test device (5) to rotate synchronously. A vibration displacement sensor X1 and a vibration velocity sensor V1 are installed at the high-speed shaft head of the high-speed gearbox (1) to monitor the vibration of the high-speed shaft during operation; a vibration displacement sensor X2 and a vibration velocity sensor V2 are installed at the middle position of the metal flexible coupling (2) to monitor the vibration of the metal flexible coupling during operation; a vibration displacement sensor X3 and a vibration velocity sensor V3 are installed at the input shaft head of the high-speed mechanical spindle (3) to monitor the vibration of the end where the high-speed mechanical spindle (3) is connected to the metal flexible coupling (2); A vibration displacement sensor X4 and a vibration velocity sensor V4 are installed at the shaft head of the output end of the high-speed mechanical spindle (3) to monitor the vibration of the high-speed mechanical spindle (3) connected to the low-temperature flexible coupling (4). The high-speed mechanical spindle (3) includes a mechanical shaft (6), a front bearing (7), a bushing (8), a rear bearing (9), a bearing housing (10), a gasket (11), a clamping cover plate (12), and a base. The bearing housing (10) is installed on the base. The front bearing (7), bushing (8), and rear bearing (9) are sequentially fitted onto the mechanical shaft (6). The front bearing (7) and the rear bearing (9) are respectively installed in the corresponding bearing holes of the bearing housing (10). The gasket (11) is placed on the outer ring end face of the rear bearing (9). The clamping cover plate (12) clamps the gasket (11) and fixes it on the bearing housing (10). The design method for high-speed mechanical spindle (3) is as follows: (1) By idling the high-speed gearbox, obtain the vibration displacement value of the high-speed shaft head of the high-speed gearbox after the high-speed gearbox reaches thermal equilibrium and the rise of its center height x1 when the initial temperature reaches temperature equilibrium; (2) Select the front bearing (7), bushing (8), and rear bearing (9), and design the overall structure of the high-speed mechanical spindle. Calculate the total friction torque of the bearings based on their size, specifications, and preload. and bearing friction power loss ; (3) Determine the total frictional torque of the bearing If the power loss due to bearing friction meets the requirements, proceed to step (4); otherwise, return to step (2) to reselect the front bearing, bushing, and rear bearing and design the overall structure of the high-speed mechanical spindle. (4) Establish a thermodynamic simulation model for the high-speed mechanical spindle, analyze the increase in center height x2 caused by bearing frictional heat generation after reaching thermal equilibrium, and perform a difference analysis with the increase in center height x1 when the high-speed gearbox reaches temperature equilibrium. If the spindle speed reaches a certain value (mm), the high-speed mechanical spindle design is considered acceptable; otherwise, the design is returned for rework until... mm; The high-speed mechanical spindle should be coupled with the high-speed shaft (13) of the high-speed gearbox (1), the metal flexible coupling (2), the low-temperature flexible coupling (4), and the spindle (14) of the end face sealing test device to perform three-span rotor dynamics simulation calculations, and check whether its first-order critical speed meets the requirements of the working speed. The bearing support stiffness should be taken as the lower limit of the bearing support stiffness range. If the requirements are met, the high-speed mechanical spindle design is considered qualified; otherwise, the high-speed mechanical spindle should be redesigned.
2. The improved rotating system for low-temperature end-face sealing test of a sliding bearing gearbox according to claim 1, characterized in that: The high-speed gearbox (1) adopts a sliding bearing for the high-speed shaft bearing, with a working speed of 20000r / min~40000r / min.
3. The improved rotating system for low-temperature end-face sealing test of a sliding bearing gearbox according to claim 2, characterized in that: The characteristics of the high-speed shaft of the high-speed gearbox (1) under static conditions are as follows: (1) When the oil pump is not turned on to supply oil to the high-speed gearbox, the center position of the high-speed shaft will change after each rotation. According to actual testing, the vertical position of the high-speed shaft changes by about 0.1mm after one rotation; (2) After the oil pump is turned on to supply oil to the high-speed gearbox and high-speed rotation is performed, as the speed increases, the high-speed shaft will gradually float in the bearing and eventually be located at an skewed position in the center of the bearing.
4. The improved rotating system for low-temperature end-face sealing test of a sliding bearing gearbox according to claim 1, characterized in that: The front bearing (7) and the rear bearing (9) are identical in model and specifications, both using EAG grease-lubricated angular contact ball bearings with a maximum operating speed of 60,000 r / min. The front bearing (7) and the rear bearing (9) are installed back to back.
5. The improved rotating system for low-temperature end-face sealing test of a sliding bearing gearbox according to claim 1, characterized in that, In step (2), the total frictional torque of the bearing satisfy In the formula: —Bearing hydrodynamic losses; —Frictional loss caused by elastic hysteresis and differential sliding of contact surfaces.
6. The improved rotating system for low-temperature end-face sealing test of a sliding bearing gearbox according to claim 1, characterized in that, The method for setting up the thermodynamic simulation calculation model of the high-speed mechanical spindle is as follows: 1) A heat source is placed on the surfaces of the two bearing balls and the inner and outer rings, and the heat generation is set to... ; 2) The initial temperature of the high-speed mechanical spindle and the environment is set to 25℃; 3) The convective heat transfer coefficient between the outer surface of the high-speed mechanical spindle and the environment is set to 5 W / m. 2 ·℃; 4) Set the coefficient of linear expansion and thermal conductivity of the bearing material and the high-speed machine spindle material; Simulation calculations yielded the increase in center height x2 of the high-speed mechanical spindle.
7. The improved rotating system for low-temperature end-face sealing test of a sliding bearing gearbox according to claim 1, characterized in that, The debugging method for the high-speed mechanical spindle (3) is as follows: S1 Adjust the coaxiality between the high-speed gearbox (1) and the high-speed mechanical spindle (3); S2 obtains the coaxiality center deviation h1 and left and right deviation k1 between the high-speed gearbox (1) and the high-speed mechanical spindle (3); S3 operates at high speed, connecting the high-speed mechanical spindle (3) to the high-speed shaft of the high-speed gearbox (1) via a metal flexible coupling (2), driving the high-speed mechanical spindle (3) through the high-speed gearbox (1), and recording the values of vibration displacement measuring points X1, X2, X3, X4, vibration velocity measuring points V1, V2, V3, V4, and the vibration acceleration value a of the high-speed mechanical spindle bearing seat; S4 keeps the left and right deviation k1 of the coaxiality between the high-speed gearbox (1) and the high-speed mechanical spindle (3) unchanged, and adjusts the center height deviation between the high-speed gearbox (1) and the high-speed mechanical spindle (3) in sequence through h1+0.01, h1+0.02, h1+0.03, h1+0.04, h1+0.05, h1+0.06, h1+0.07, h1+0.08, h1+0.09, h1+0.
10. Under each center height deviation, high-speed operation is carried out, and the values of vibration displacement measuring points X1, X2, X3, X4, vibration velocity measuring points V1, V2, V3, V4, and vibration acceleration value a of the high-speed mechanical spindle bearing seat are recorded. S5 When a set of vibration data X1, X2, X3, X4, V1, V2, V3, V4, a is at its minimum value, it is considered that the center height coaxiality of the high-speed gearbox (1) and the high-speed mechanical spindle (3) corresponding to the set of vibration data is at its best. At this time, the dynamic characteristics of the double-span rotor composed of the high-speed shaft (13) of the gearbox and the high-speed mechanical spindle are optimal and not easily affected by external excitation. Record the center height deviation value h corresponding to the set of vibration data. S6 Keeping the center height deviation value h constant, adjust the left and right deviations of the high-speed gearbox (1) and the high-speed mechanical spindle (3) sequentially through k1=-0.05, -0.04, -0.03, -0.02, -0.01, 0, 0.01, 0.02, 0.03, 0.04, 0.05mm, and conduct high-speed operation under each left and right deviation, recording the values of vibration displacement measuring points X1, X2, X3, X4, vibration velocity measuring points V1, V2, V3, V4, and high-speed machine... When the vibration acceleration value a of the mechanical spindle bearing housing is at its minimum, it is considered that the left and right deviation coaxiality of the high-speed gearbox (1) and the high-speed mechanical spindle (3) corresponding to the set of vibration data X1, X2, X3, X4, V1, V2, V3, V4, a is at its minimum. At this time, the dynamic characteristics of the double-span rotor composed of the high-speed shaft (13) of the gearbox and the high-speed mechanical spindle are optimal and not easily affected by external excitation. Record the left and right deviation value k corresponding to the set of vibration data. S7 adjusts the coaxiality of the high-speed gearbox (1) and the high-speed mechanical spindle (3) according to the center height and left and right deviation values h and k obtained above. After the adjustment is completed, fix the base of the high-speed mechanical spindle (3) and complete the debugging.