Radial cylindrical roller bearing friction torque testing machine

Abstract

The application belongs to a testing machine device, and particularly relates to a large radial load cylindrical roller bearing friction torque testing machine, which comprises a rack, a main shaft box, a horizontally arranged mandrel, a balance beam and a supporting seat, the supporting seat and the main shaft box are respectively arranged on the rack, the mandrel is rotatably arranged on the supporting seat and the main shaft box at two ends, a measured bearing is sleeved on the mandrel, the balance beam is sleeved on the measured bearing, a force measuring rod is arranged on the balance beam, a tension sensor is connected to the force measuring rod, two sides of the balance beam are respectively provided with lifting points, a line connecting the centers of the lifting points passes through the axis of the mandrel, and the lifting points are symmetrically provided with loading weights. The measurement accuracy of the testing machine is greatly improved.

Description

Technical Field

[0001] This invention pertains to testing equipment, specifically a large radial load cylindrical roller bearing friction torque testing machine. Background Technology

[0002] Bearing friction torque is one of the important parameters of bearing performance. Bearing friction torque directly affects the operating resistance and energy loss of the bearing during use. Excessive friction torque will not only cause the bearing to heat up too quickly and accelerate the deterioration of the lubricant, but also increase the wear on the bearing surface and affect the service life of the bearing.

[0003] Because cylindrical roller bearings can only withstand radial loads, a radial load must be applied when measuring their frictional torque performance. Currently, the measuring structure of a cylindrical roller bearing frictional torque testing machine involves mounting the inner ring of the bearing under test on a mandrel, placing a measuring ring on the outer ring, and winding a force transmission rope around the measuring ring. Both ends of the force transmission rope are connected to loading devices, and a force measuring rod is connected to the measuring ring, with the other end of the force measuring rod connected to a force measuring element. During measurement, the loading device applies a radial load to the bearing under test through the force transmission rope. The inner ring of the bearing rotates with the mandrel, and the frictional torque of the bearing under test is measured by the force measuring rod and the force measuring element. Because the force transmission rope undergoes bending deformation and relative slippage during the rotation of the measuring ring, the frictional torque of the bearing under test must overcome the bending deformation of the force transmission rope and the frictional force between the force transmission rope and the measuring ring to be transmitted to the force measuring rod, thus causing measurement errors. In particular, when a large radial load is applied, the diameter and stiffness of the force transmission rope required will increase, and the friction between the force transmission rope and the measuring ring will also increase, which will increase the measurement error.

[0004] Currently, cylindrical roller bearing friction torque testing machines have low measurement accuracy under large radial load conditions, making it difficult to accurately reflect the friction torque of cylindrical roller bearings under heavy load conditions, and also failing to meet the needs of dynamic friction torque monitoring of bearings. Therefore, it is necessary to improve the measurement accuracy of cylindrical roller bearing friction torque testing machines under large radial load conditions. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a large radial load cylindrical roller bearing friction torque testing machine. After improvements to the loading and measuring devices, the measurement accuracy is enhanced. The technical solution adopted by this invention is as follows:

[0006] A large radial load cylindrical roller bearing friction torque testing machine includes a frame, a spindle box, a horizontally arranged mandrel, a balance beam, and a support base. The support base and the spindle box are respectively mounted on the frame. The two ends of the mandrel are rotatably mounted on the support base and the spindle box, respectively. The bearing to be tested is sleeved on the mandrel. The balance beam is sleeved on the bearing to be tested. A force measuring rod is mounted on the balance beam. A tension sensor is connected to the force measuring rod. There are suspension points on both sides of the balance beam. The line connecting the centers of the suspension points passes through the axis of the mandrel. Weights for loading are symmetrically suspended on the suspension points.

[0007] The aforementioned large radial load cylindrical roller bearing friction torque testing machine has rotatable pulleys on both sides of the balance beam, with lifting rings fitted on the pulleys, and the weights connected to the lifting rings by pull ropes.

[0008] In the aforementioned large radial load cylindrical roller bearing friction torque testing machine, the weights are located inside the protective cover within the frame. Magnetic strips are respectively provided on the two sets of weights and the protective cover. There is a horizontal mutual repulsive magnetic force between the magnetic strips of the weights and the protective cover, as well as between the magnetic strips of the two sets of weights.

[0009] In the aforementioned large radial load cylindrical roller bearing friction torque testing machine, the force measuring rod and the tension sensor are connected by a spring.

[0010] The aforementioned large radial load cylindrical roller bearing friction torque testing machine has a liftable lifting seat inside the frame for placing weights.

[0011] The aforementioned large radial load cylindrical roller bearing friction torque testing machine has a tie rod inside the spindle box, with one end of the tie rod screwed to a mandrel and the other end connected to a transmission mechanism.

[0012] The aforementioned large radial load cylindrical roller bearing friction torque testing machine has a slide table on its frame, and the support seat is slidably mounted on the slide table.

[0013] The beneficial effects of this invention are as follows:

[0014] Firstly, during measurement, under the frictional torque of the bearing being measured, the balance beam will tilt as the outer ring of the bearing rotates. In existing technologies, the height of the load application points on both sides of the balance beam can be arbitrarily set. When the line connecting the load application points on both sides of the balance beam does not pass through the axis of the mandrel, the force arms of the loads on both sides of the balance beam relative to the axis of the mandrel are unequal when the balance beam tilts, resulting in an imbalance of torque on both sides of the balance beam, thus causing measurement errors. This invention symmetrically sets separate load application points on both sides of the balance beam, and further ensures that the line connecting the two application points always passes through the axis of the mandrel. Therefore, even when the balance beam tilts, the force arms of the loads on the two application points relative to the axis of the mandrel are always equal, and the torque exerted by the loads on both sides of the balance beam on the bearing being measured is always balanced. This avoids the imbalance of load torque caused by the tilt of the balance beam, thereby improving measurement accuracy.

[0015] Secondly, in existing technologies, the load-connecting rope is wound around the outer ring of the bearing or the balance beam. The rope is typically made of steel wire to transmit large loads. Because the outer ring of the bearing being measured rotates under the influence of frictional torque during measurement, the rope also rotates with it. Therefore, the frictional torque of the bearing needs to overcome the bending deformation of the rope to be transmitted to the tension sensor, thus affecting the measurement results. As the load increases, the required diameter and bending stiffness of the rope also increase, and the bending deformation of the rope has a significant impact on the accuracy of frictional torque measurement. The loading method of this invention uses two independent ropes suspended on lifting rings on both sides of the balance beam. Therefore, the ropes will not bend or deform due to the rotation of the outer ring of the bearing being measured. Furthermore, the lifting rings on both sides of the balance beam can rotate flexibly, thereby reducing friction between the ropes and the balance beam and greatly improving measurement accuracy.

[0016] Thirdly, in existing technologies, the force measuring rod and the tension sensor are connected by a connecting rope. The radial runout and oscillation of the mandrel cause the force measuring rod to move up and down, and the way the force measuring rod is installed on the balance beam amplifies the mandrel runout. The impulse generated by the up and down movement of the force measuring rod causes significant fluctuations in the measurement data of the tension sensor, thus affecting the measurement accuracy of the friction torque. This application connects the force measuring rod to the tension sensor through a low-stiffness tension spring, which can filter out the influence of mandrel runout on the measurement accuracy of friction torque, thereby improving the measurement accuracy. The specific principle is that the tensile deformation of the spring reduces the force caused by the impulse of the force measuring rod's runout. The magnitude of the force caused by the runout impulse is equal to the product of the spring stiffness and the runout displacement. When the spring stiffness is low, the maximum runout displacement of the force measuring rod is much smaller than the maximum tensile deformation of the spring. At this time, the force generated by the runout of the force measuring rod is greatly reduced. Therefore, the spring has a filtering effect on high-frequency mandrel runout and can transmit the constant or low-frequency changing tension generated by the friction torque of the measured bearing.

[0017] Fourth, the frictional torque of the bearing being measured is very small, typically between 0.1 and 2 N·m. Existing technologies use contact-type sliding guide mechanisms to limit the swing of the weights, such as cylindrical guide devices. When the swing of the weight exceeds the guide clearance, contact sliding friction occurs between the weight and the guide device. Under heavy loads, due to the large weight of the weight, the inertial force during its swing is also large. Therefore, the frictional torque caused by the contact between the weight and the guide device cannot be ignored relative to the frictional torque of the bearing being measured, thus affecting measurement accuracy. Furthermore, the weight is flexibly suspended by a rope. In practice, it is difficult for the suspension point of the weight to perfectly coincide with or be symmetrical with its geometric center, causing the weight to tilt. When the weight contacts the guide device due to this tilt, the contact force and friction between the weight and the guide device increase with the mass of the weight. Therefore, under heavy loads, the contact friction between the weight and the guide device can cause significant measurement errors. Furthermore, the axial movement and oscillation of the mandrel will cause the balance beam to move axially and oscillate, which in turn causes the weights to oscillate, resulting in a momentary imbalance of the applied torque on both sides of the balance beam, thus producing measurement errors. This invention utilizes magnetic repulsion by placing magnetic strips around the weights, eliminating friction caused by contact or reducing the wobbling problem caused by mandrel movement, thereby further increasing measurement accuracy.

[0018] Fifth, existing technologies that connect sensors and loading devices in series suffer from problems such as large sensor range and low resolution. In this invention, the force measuring device, consisting of a force measuring rod, spring, and tension sensor, is designed independently from the loading device, consisting of weights, rope, ring, and pulley. The range of the tension sensor is not limited by the load size but is only related to the friction torque of the bearing being measured. Therefore, a small-range, high-resolution tension sensor can be used to measure the friction torque of the bearing under large radial load conditions.

[0019] Sixth, the spindle is easy to disassemble and assemble, and the support base is adjustable and easy to use. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the main structure of the present invention;

[0021] Figure 2 This is a side view of the structure of the present invention;

[0022] Figure 3 This is a schematic diagram of the connection between the mandrel and the spindle of the present invention;

[0023] Figure 4 This is a diagram of the mandrel structure of the present invention;

[0024] Figure 5 This is a schematic diagram of the balance beam structure of the present invention.

[0025] Figure 6 This is a simulation diagram of the forces acting on the balance beam of this invention;

[0026] Figure 7 To and Figure 6 A simulation diagram of the forces acting on the balance beam for comparison.

[0027] In the diagram: 1. Main spindle motor; 2. Synchronous pulley; 3. Mandrel; 4. Spindle box; 41. Main spindle; 5. Tie rod; 6. Bearing under test; 7. Balance beam; 71. Balance ring; 72. Connecting block; 73. Pulley; 8. Support base; 9. Slide table; 10. Frame; 11. Weight; 12. Lifting seat; 13. Lifting ring; 14. Force measuring rod; 15. Spring; 16. Tension sensor; 17. Magnetic strip; 18. Transition ring; 19. Pull rope; 20. Connecting plate. Detailed Implementation

[0028] The radial load cylindrical roller bearing friction torque testing machine of this embodiment can measure the friction torque of cylindrical roller bearings under different speeds and loads, with high measurement accuracy and easy disassembly of the tested bearing 6. The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Left and right directions refer to... Figure 1 The left and right directions are shown.

[0029] The testing machine is horizontally mounted. The frame 10 is generally rectangular. A spindle box 4 and a slide table 9 are fixed on the top surface of the frame 10. A support seat 8 is slidably mounted on the slide table 9. The spindle box 4 contains a ball bearing with high rotational precision to assemble the tie rod 5. The two ends of the mandrel 3 are respectively mounted on the support seat 8 and the spindle 41. The bearing to be tested 6 is mounted on the mandrel 3. A transition ring 18 is fitted on the bearing to be tested 6, and a balance beam 7 is fitted on the transition ring 18. The bearing to be tested 6 and the mandrel 3 are interference-fitted. Different sizes of mandrel 3 and transition ring 18 are selected according to different bearing models.

[0030] The transmission mechanism that provides power to the spindle box 4 includes a spindle motor 1 and a synchronous pulley 2 installed in the frame 10. The speed of the spindle motor 1 can be controlled by an externally connected computer. The synchronous pulley 2 drives the spindle 41 to rotate. The pull rod 5 is located in the center hole of the spindle 41. One end of the pull rod 5 is screwed to the mandrel 3, and the other end is fastened to the spindle 41 with a nut, thereby causing the mandrel 3 to rotate.

[0031] like Figure 1 As shown, the right half of the mandrel 3 has a tapered shaft section, which improves coaxiality accuracy when it mates with the spindle 41. The right end of the shaft has a threaded hole for connecting the pull rod 5, and the left end of the shaft is fitted with a bearing and mounted on the support seat 8. The left and right sliding of the support seat 8 can ensure that the mandrel 3 and the pull rod 5 are locked or disengaged. This mounting method of the mandrel 3 makes it very convenient to disassemble the bearing 6 under test, thus improving efficiency.

[0032] The balance beam 7 has connecting blocks 72 on both sides of the balance ring 71, and pulleys 73 are mounted on the connecting blocks 72. The balance beam 7 is symmetrically equipped with lifting rings 13 to suspend the weights 11, ensuring that the center point of the line connecting the two lifting rings 13 always passes through the axis of the spindle 3. Even if the balance beam 7 is tilted, the torque exerted by the weights 11 on the measured bearing 6 and the spindle 3 remains equal. Figure 6 As shown. This reduces the torque exerted by the unbalanced load on the balance beam 7, improving measurement accuracy. The specific force analysis of the balance beam 7 is as follows:

[0033] refer to Figure 6 The line O1O2 connecting the centers of the pulleys 73 on both sides of the balance beam 7 passes through the center O of the spindle 3. When the balance beam 7 rotates counterclockwise around the center O of the spindle 3 by any angle φ under the action of the friction torque (counterclockwise) of the bearing 6 being measured, the distance from the center O1O2 to O is always equal, i.e., a1=a2, thus ensuring that the gravitational torque generated by the weights 11 on both sides is always equal in magnitude and opposite in direction;

[0034] If the line O1O2 connecting the load application points on both sides of the balance beam 7 does not pass through the center O of the mandrel, such as Figure 7 As shown, when the balance beam 7 rotates counterclockwise around the center O of the spindle 3 by any angle φ under the action of the frictional torque (counterclockwise) of the bearing 6 being measured, the distances from the center of O1O2 to O are respectively

[0035]

[0036] Where L is the length of O1O2, a1≠a2. Since the loads on both sides are equal, the gravitational moments on both sides of the balance beam 7 are not equal, causing measurement errors. Therefore, in this embodiment, the center point of the line connecting the lifting rings 13 of the two lifting loads always passes through the axis of the mandrel 3, ensuring that the torque of the weight 11 on the measured bearing 6 and the mandrel 3 is always equal, thereby reducing the problem of load imbalance and improving measurement accuracy.

[0037] In existing technology, the pull rope 19 connecting the load is a 7 wound around the outer ring of the bearing 6 being measured or the balance beam. The pull rope 19 is generally made of steel wire rope to transmit large loads. During measurement, the outer ring of the bearing 6 being measured will rotate under the action of frictional torque, and the pull rope 19 will also rotate accordingly. Therefore, the frictional torque of the bearing 6 being measured needs to overcome the bending deformation of the pull rope to be transmitted to the tension sensor 16, thus affecting the measurement results. As the load increases, the required diameter and bending stiffness of the pull rope 19 also increase, and the bending deformation of the pull rope 19 has a significant impact on the accuracy of the frictional torque measurement. In this embodiment, as... Figure 1As shown, two independent pull ropes 19 are used to suspend the loads on the lifting rings 13 on both sides of the balance beam 7, so the pull ropes 19 will not bend or deform due to the rotation of the outer ring of the bearing 6 being measured. Furthermore, the lifting rings 13 are fitted onto the pulleys 73 to rotate and keep the pull ropes 19 vertical. During equipment operation, this reduces frictional interference between the lifting rings 13 and the balance beam 7, greatly improving measurement accuracy. The weights 11 are fixed in multiple rows by the connecting plate 20.

[0038] In existing technologies, contact-type sliding guide mechanisms are used to limit the swing of the weight 11, such as cylindrical guide devices. When the swing of the weight exceeds the guide clearance, contact sliding friction occurs between the weight 11 and the guide device. Under heavy loads, due to the large weight of the weight 11, the inertial force during its swing is also large. Consequently, the frictional torque caused by the contact between the weight 11 and the guide device cannot be ignored relative to the frictional torque of the bearing 6 being measured, thus affecting measurement accuracy. Furthermore, the weight 11 is flexibly suspended by a rope. In actual operation, it is difficult for the suspension point of the weight 11 to completely coincide with or be symmetrical with the geometric center of the weight 11, so the weight 11 will tilt. When the weight 11 contacts the guide device due to tilting, the contact force and friction between the weight 11 and the guide device increase with the increase of the mass of the weight 11. Therefore, under heavy loads, the contact friction between the weight 11 and the guide device will cause a large measurement error. Furthermore, the axial movement and oscillation of the mandrel 3 will cause the balance beam 7 to move axially and oscillate, which will cause the weight 11 to oscillate as well, resulting in an instantaneous imbalance of the loading torque on both sides of the balance beam 7, thus generating measurement errors.

[0039] Therefore, in this embodiment, the magnetic repulsion of the magnetic strip 17 is utilized to eliminate friction caused by contact with the weight 11, further increasing measurement accuracy. Specifically, as... Figure 1 and Figure 2 As shown, during use, the weight 11 is located within a protective cover inside the frame 10. In this embodiment, horizontal magnetic strips 17 with mutual magnetic repulsion are respectively provided between the four outer corners of the weight 11 and the four edges of the protective cover, as well as between the two sets of weights 11, to constrain the swaying of the weight 11, thereby reducing the interference of the loading torque of the weight 11 on the spindle 3, ensuring the smooth rotation of the spindle 3, and further improving the measurement accuracy. A liftable lifting seat 12 is provided below the weight 11. When no loading is required, the lifting seat 12 is raised to support the weight 11. The lifting structure of the lifting seat 12 adopts a ball screw.

[0040] A force-measuring rod 14 is mounted on the balance beam 7, and a tension sensor 16 is connected to the force-measuring rod 14. The tension sensor 16 is used to collect the frictional force value of the bearing 6 under test. The frictional torque value is the measured frictional force multiplied by the lever arm (the horizontal straight-line distance from the rotation center of the bearing 6 under test to the outer end of the force-measuring rod 14). The force-measuring rod 14 and the tension sensor 16 are connected by a spring 15, which can reduce the influence of the vibration of the bearing 6 under test on the frictional force, further improve the measurement accuracy, and make the measurement of the tension sensor 16 more stable. The spring 15 has the functions of transmitting tension and damping vibration. The specific principle is explained as follows:

[0041] In the existing technology, the force measuring rod 14 and the tension sensor 16 are connected by a rigid rope. The radial runout and swing of the spindle 3 will cause the force measuring rod 14 to jump up and down. Moreover, the way the force measuring rod 14 is installed on the balance beam 7 has an amplifying effect on the runout of the spindle 3. The impulse generated by the up and down jump of the force measuring rod 14 will cause serious fluctuations in the measurement data of the tension sensor 16, thereby affecting the measurement accuracy of the friction torque.

[0042] This application connects the force-measuring rod 14 to the tension sensor 16 via a low-stiffness tension spring 15, which can filter out the influence of spindle 3 runout on the accuracy of friction torque measurement, thus improving measurement accuracy. The specific principle is as follows: the tensile deformation of the spring 15 reduces the force caused by the runout impulse of the force-measuring rod 14. The magnitude of the runout impulse force is equal to the product of the spring 15 stiffness and the runout displacement. When the spring 15 stiffness is low, the maximum runout displacement of the force-measuring rod 14 is much smaller than the maximum tensile deformation of the spring 15. At this point, the force generated by the runout of the force-measuring rod 15 is greatly reduced. Therefore, the spring 15 has a filtering effect on the high-frequency runout of the spindle 3, while simultaneously transmitting the constant or low-frequency changing tension generated by the friction torque of the measured bearing 6.

[0043] The force-measuring device, consisting of a force-measuring rod 14, a tension spring 15, and a force sensor 16, is designed independently of the loading device, which consists of a weight 11, a pull rope 19, a lifting ring 13, and a pulley 73. The range of the force sensor 16 is not limited by the load size, but only by the frictional torque of the bearing 6 being measured. Therefore, a small-range, high-resolution force sensor 16 can be used to measure the frictional torque of the bearing 6 under large radial load conditions. In contrast, connecting the sensor and the loading device in series in the prior art results in a large sensor range and low resolution.

[0044] The method for using this testing machine to measure the frictional torque of cylindrical roller bearings is as follows:

[0045] Step 1: Install the bearing 6 to be tested on the mandrel 3, and assemble the transition ring 18 and the balance beam 7 on the outer ring of the bearing to be tested;

[0046] Step 2: Insert the tapered end of the mandrel 3 into the spindle box 4, and secure the mandrel 3 with the pull rod 5;

[0047] Step 3: Slide the support 8 to assemble it with the left end of the spindle 3, and then lock the support 8 onto the slide 9;

[0048] Step 4: Connect the lifting ring 13 to the balance beam 7, and lower the lifting seat 12 to apply the load.

[0049] Step 5: Connect the force measuring rod 14 extending from the balance beam 7 to the tension sensor 16 using spring 15, level the weight 11, and zero the tension sensor 16;

[0050] Step 6: Control the spindle speed of mandrel 3 on the computer and start the measurement.

[0051] The main interface of the testing machine allows users to set test parameters such as spindle speed and measurement time, and displays and saves test results such as friction torque and friction coefficient in real time. Experimental results can be output as friction torque-time and friction coefficient-time, including the average, maximum, minimum, and fluctuation values ​​of the measured values.

Claims

1. A large radial load cylindrical roller bearing friction torque testing machine, comprising a frame (10), a spindle box (4), a horizontally arranged mandrel (3), a balance beam (7), and a support base (8), wherein the support base (8) and the spindle box (4) are respectively mounted on the frame (10), the two ends of the mandrel (3) are respectively rotatably mounted on the support base (8) and the spindle box (4), the bearing to be tested (6) is sleeved on the mandrel (3), the balance beam (7) is sleeved on the bearing to be tested (6), a force measuring rod (14) is mounted on the balance beam (7), and a tension sensor (16) is connected to the force measuring rod (14), characterized in that: The balance beam (7) has lifting points on both sides, and the line connecting the centers of the lifting points passes through the axis of the spindle (3). Loading weights (11) are symmetrically suspended on the lifting points. The balance beam (7) has rotatable pulleys (73) on both sides, and lifting rings (13) are fitted on the pulleys (73). The weights (11) are connected to the lifting rings (13) by a pull rope (19). The weights (11) are located inside the protective cover inside the frame (10). The two sets of weights (11) and the protective cover are respectively provided with magnetic strips (17). There are horizontally repulsive magnetic forces between the weights (11) and the magnetic strips (17) of the protective cover, and between the magnetic strips (17) of the two sets of weights (11). The force measuring rod (14) is connected to the tension sensor (16) by a spring (15).

2. The large radial load cylindrical roller bearing friction torque testing machine according to claim 1, characterized in that: The frame (10) is provided with a liftable lifting seat (12) for placing weights (11).

3. The large radial load cylindrical roller bearing friction torque testing machine according to claim 1, characterized in that: The spindle box (4) is equipped with a pull rod (5), one end of which is screwed to the mandrel (3) and the other end is connected to the transmission mechanism.

4. The large radial load cylindrical roller bearing friction torque testing machine according to claim 1, characterized in that: The frame (10) is provided with a slide (9), and the support base (8) is slidably mounted on the slide (9).

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