CN104132886A - Device for testing friction coefficient of precision bearing ball and cage pocket - Google Patents

Abstract

The invention relates to a friction coefficient testing device for precision bearing balls and cage pockets. It includes a loading mechanism supported by an air bearing linear guide and a torque measuring mechanism supported by an air bearing. The loading mechanism is a rigid connection between a steel ball and a motor shaft. The motor is fixed on one end of the air bearing linear guide, and a force sensor is installed on the other end and fixed on the bracket. The differential head is driven by the screw to push the pressure sensor, and the pressure is transmitted to the motor shaft through the air-floating linear guide rail and then to the contact surface between the steel ball and the ball pocket of the cage. The loading mechanism is fixed on the three-dimensional mobile platform; the torque measurement mechanism One end of the rotating shaft of the air bearing is connected with the half ball pocket of the cage, and the other end is connected with the torque sensor. The invention can accurately and effectively test the micro-friction coefficients under different contact positions between precision bearing balls and cage pockets, different lubricating states, matching pairs of different materials and different working conditions.

Description

Measuring device for friction coefficient between precision bearing ball and cage pocket

technical field

The invention relates to the field of friction of precision rolling bearings, in particular to a friction coefficient testing device for precision bearing balls and cage pockets. the

Background technique

Rolling bearings are components that support rotating shafts and are widely used in various fields of the machinery industry. Rolling bearings have the characteristics of low friction, but there are still complex friction phenomena inside them. Among them, the sliding friction between the steel ball and the raceway and the sliding friction between the steel ball and the cage not only consume energy, but more importantly, generate large Wear causes the bearing to lose precision. the

Gyroscopes are used in the inertial instruments of manned spacecraft, satellites, aircraft, missiles and marine ships to detect flight attitude, ship orientation and angular velocity. In the inertial navigation systems of these carriers, gyroscopes are extremely important sensors. The key components in the gyroscope are the gyro rotor bearings that support the gyro motor rotor and the gyro frame bearings that support the gyro frame. The gyro frame bearings with high sensitivity and low frictional moment and the high-precision and long-life gyro rotor bearings are the factors that affect the above-mentioned carriers and weapons. The important factor of equipment orientation and positioning system, the sliding friction between bearing parts is the root cause of the failure of the accuracy of the above-mentioned precision instrument bearings. Therefore, the coefficient of sliding friction is an important parameter for theoretical analysis and experimental research of bearings. At present, there have been a lot of experimental researches to simulate the sliding friction of the point contact between the bearing ball and the raceway, such as a typical ball-on-disk test machine. However, the experimental research on the sliding friction between the precision instrument bearing ball and the cage has not been reported. The main reason is that the sliding friction between the ball and the cage is small and difficult to measure. It is usually ignored in non-precision bearings, but in sensitive balls. In the bearing, the influence of the sliding friction between the ball and the cage on the total friction torque of the bearing cannot be ignored. In this regard, a device for testing the friction coefficient between the precision bearing ball and the pocket of the cage is proposed to realize the test of the friction coefficient of the bearing ball and the pocket of the cage at different contact parts, different lubrication states, different materials and different working conditions . the

Contents of the invention

The purpose of the present invention is to overcome the technical defects that the precision bearing ball and the cage have a small friction coefficient and are not easy to measure, and propose a friction coefficient testing device for the precision bearing ball and the cage pocket to realize the bearing ball and cage under different working conditions. The friction coefficient of the ball pocket is convenient and accurate to test. the

In order to achieve the above purpose, the concept of the present invention is: for the sliding friction between the bearing ball and the ball pocket of the cage, the friction coefficient of the contact surface can be calculated according to the applied force, the eccentricity of the contact point and the measured torque. In order to make the measurement of load and torque more accurate, air bearing linear guides and air bearings, which can be regarded as zero friction, are used as the supporting system. The bearing ball is connected with the motor, and the motor is directly fixed on the guide rod of the air-floating linear guide rail, which is convenient for loading, and the differential head screw transmission top pressure sensor is used to realize constant value loading. The air bearing linear guide rail is fixed on the three-dimensional mobile platform, which can realize the movement of the loading system in three directions, so that the bearing ball and the ball pocket of the cage can contact at different positions (inside or edge of the ball pocket). The torque sensor and the air bearing stator are fixed in the seat hole support of the coaxial center line. The air bearing bears the radial force generated by the contact between the ball and the cage, while the torque sensor only bears the torque, which can prevent the torque sensor from being damaged due to additional load. The ball and cage ball pockets are respectively bonded to the connecting shaft, and the materials of the above-mentioned bearing parts are replaced and bonded to a new connecting shaft to test the coefficient of friction between matching pairs of different materials. the

According to above-mentioned inventive conception, achieve the object of the invention through following technical scheme:

A friction coefficient testing device for precision bearing balls and cage pockets, including a loading mechanism and a torque measuring mechanism, characterized in that: the loading mechanism and the torque measuring mechanism are respectively supported by an air bearing linear guide rail and an air bearing; the loading mechanism is The steel ball to be tested is bonded to a connecting shaft, which is connected to the rotating shaft of a motor, and the motor is fixed on one end of the air-floating linear guide, while a force sensor is installed on the other end of the air-floating linear guide, which is fixed on a bracket A differential head passes through the screw drive to press the pressure sensor; the pressure of the differential head passes through the pressure sensor to the rotating shaft of the motor through the air bearing linear guide rail, and then to the contact surface between the steel ball and the ball pocket of the cage; the torque measuring mechanism A cage ball pocket is bonded to another connecting shaft, and then connected to one end of the rotating shaft of the air bearing, and the other end of the rotating shaft is connected to a torque sensor through a coupling, and the torque sensor is fixed to the stator of the air bearing In the support of a coaxial core line seat hole; the moving direction of the air bearing linear guide is perpendicular to the motor axis; the motor drives the steel ball to rotate, and the torque generated by the sliding friction between the steel ball and the cage ball pocket is transmitted through the air bearing For torque sensors, the coefficient of friction of the contact surface can be calculated from the applied pressure, the eccentricity of the contact and the measured torque.

The bracket is fixed on a three-dimensional mobile platform together with the air-floating linear guide rail, and the contact between the steel ball and the different parts of the ball pocket of the cage can be realized through fine-tuning in three directions. the

The steel ball is bonded to the connecting shaft, and the end surface of the connecting shaft is processed into a tapered hole to ensure that the center of the ball is aligned with the axis, and a straight hole is drilled from one end of the tapered hole to the other end of the shaft. The motor shaft is matched, and the machining of the shaft and the hole is completed under one clamping. the

Three setscrews are evenly arranged in the circumferential direction of the hole where the connecting shaft cooperates with the motor rotating shaft, so as to adjust the alignment between the connecting shaft and the motor rotating shaft. the

The ball pocket is bonded to the connecting shaft, and the end surface of the connecting shaft is also processed with a tapered hole to ensure that the center of the cage ball pocket is aligned with the axis of the connecting shaft, and the other end of the connecting shaft is tightly fitted with the rotating shaft of the air bearing Connect to transmit torque. the

The torque sensor and the air bearing are fixed in the support of the coaxial core line seat hole, so that the air bearing bears the radial force acting on the ball pocket of the cage and transmits the torque, and the torque sensor only bears the torque. Due to the air bearing, the torque is transmitted with negligible friction. the

The three-dimensional mobile platform and the support are installed on the base; when assembling, the upper surface and the long side of the base are used as the reference to ensure that the axis of the seat hole in the support is parallel to the reference side, and the air-floating straight line The guide rail is perpendicular to the reference edge and parallel to the reference surface, so as to ensure that the motor shaft is parallel to the rotating shaft of the air bearing. the

Compared with the prior art, the present invention has the following prominent substantive features and significant advantages:

Because the present invention adopts the air-floating linear guide rail and the air-floating bearing support, the friction in the force and torque transmission process can be neglected. It can accurately and effectively test the small friction coefficient of precision bearing balls and cage pockets in different contact parts, different lubrication states, different material matching pairs and different working conditions.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is the structural representation of ball and connecting shaft among the present invention;

Fig. 3 is a schematic structural view of the cage ball pocket and the connecting shaft in the present invention;

Fig. 4 is the structural representation of differential head support among the present invention;

Fig. 5 is a schematic diagram of the structure of the coupling between the torque sensor and the air bearing rotating shaft in the present invention.

Fig. 6 is a structural schematic diagram of the air bearing and the torque sensor support in the present invention. the

Detailed ways

Preferred embodiments of the present invention are described in detail as follows in conjunction with accompanying drawings:

Embodiment one:

Referring to Fig. 1, a friction coefficient testing device for precision bearing balls and cage pockets, including a loading mechanism (I) and a torque measuring mechanism (II), is characterized in that: the loading mechanism (I) and the torque measuring mechanism ( Ⅱ) Supported by the air bearing linear guide (12) and the air bearing (5) respectively; the loading mechanism (I) is that the steel ball (8) to be tested is bonded to a connecting shaft (9), and the connecting shaft (9) is connected to a The rotating shaft of motor (10) is connected, and this motor (10) is fixed on one end of air-floating linear guide (12), and the other end of air-floating linear guide (12) is installed a force sensor (14), is fixed on a bracket (15 ) on a differential head (16) through the screw drive top pressure sensor (14); the pressure of the differential head (16) through the pressure sensor (14) is transmitted to the rotating shaft of the motor (10) through the air bearing linear guide (12), Then it is transmitted to the contact surface between the steel ball (8) and the cage ball pocket (7); the torque measuring mechanism (II) is a cage ball pocket (7) bonded to another connecting shaft (6), Then it is connected with one end of the rotating shaft of the air bearing (5), and the other end of the rotating shaft is connected with a torque sensor (3) through a shaft coupling (4), and the torque sensor (3) is fixed with the stator of the air bearing (5) In the support (2) of a coaxial core line seat hole; the moving direction of the air-floating linear guide (12) is perpendicular to the axis of the motor (10); the motor (10) drives the steel ball (8) to rotate, and the steel ball (8) The torque generated by the sliding friction with the cage ball pocket (7) is transmitted to the torque sensor (3) through the air bearing (5), and the contact can be calculated according to the applied pressure, the eccentricity of the contact point and the measured torque Surface friction coefficient.

Embodiment two:

Referring to Figures 1 to 6, this embodiment is basically the same as Embodiment 1, and the special features are as follows:

The bracket (15) is fixed on a three-dimensional mobile platform (17) together with the air-floating linear guide rail (12); the three-dimensional fine-tuning of the three-dimensional mobile platform (17) can realize the adjustment of the steel ball (8) and the ball pocket of the cage. (7) Contact of different parts. The steel ball (8) is bonded to the connecting shaft (9), and the end surface of the connecting shaft (9) is processed into a tapered hole to ensure that the center of the ball is aligned with the axis, and a straight hole is drilled from one end of the tapered hole To the other end of the shaft, the hole is matched with the motor shaft, and the machining of the shaft and the hole is completed under one clamping. Three setscrews are evenly arranged in the circumferential direction of the hole where the connecting shaft (9) and the rotating shaft of the motor (10) cooperate, so as to adjust the centering of the connecting shaft (9) and the rotating shaft of the motor (10). The cage ball pocket (7) is bonded to the connecting shaft (6), and the end surface of the connecting shaft (6) is also processed into a tapered hole to ensure that the center of the cage ball pocket (7) is aligned with the connecting shaft (6). The center line is centered, and the other end of the connecting shaft (6) is tightly fitted with the rotating shaft of the air bearing (5) to transmit torque. The torque sensor (3) and the air bearing (5) are fixed in the support (2) of the coaxial core line seat hole, so that the air bearing (5) bears the diameter acting on the ball pocket (7) of the cage To force and transmit torque, the torque sensor (3) only bears the torque; due to the air bearing, the friction in the process of torque transmission is negligible. The three-dimensional mobile platform (17) and the support (2) are installed on a base (1); during assembly, the upper surface and the long side of the base (1) are used as a reference to ensure that the support (2) ) The axis of the seat hole is parallel to the reference side, ensuring that the air bearing linear guide (12) is perpendicular to the reference side and parallel to the reference plane, thereby ensuring that the motor (10) rotating shaft is parallel to the air bearing (5) rotating shaft.

Embodiment three:

This embodiment is: Referring to FIG. 1 , a friction coefficient testing device for precision bearing balls and cage pockets, including a loading and torque measuring mechanism. The feature of the loading mechanism is: the steel ball (8) and the connecting shaft (9) are bonded with an adhesive, see Figure 2, the end surface of the connecting shaft is processed with a tapered hole to ensure that the center of the ball is aligned with the axis line, and from One end of the tapered hole is drilled straight to the other end of the shaft, and the hole is matched with the motor shaft. The machining of the shaft and the hole is completed under one clamping, and bonded with the ball on the machine tool. Three setscrews are evenly arranged in the circumferential direction of the hole where the connecting shaft (9) and the stepping motor (10) are matched, so as to adjust the alignment between the connecting shaft and the motor shaft, and the radial runout of the steel ball is controlled within 30 μm when the motor rotates . The motor (10) is connected to one end of the air-floating linear guide (12) through a right-angle plate (11), the other end of the air-floating linear guide is installed with a pressure sensor (14), and the differential head (16) fixed on the bracket (15) passes through The screw drives the top pressure sensor, and the pressure is transmitted to the motor shaft through the air-floating linear guide rail, and then transmitted to the contact surface between the steel ball and the ball pocket (7) of the cage. The support (15), referring to Fig. 4, is fixed on the three-dimensional mobile platform together with the air bearing linear guide rail (12).

on platform (17). Adjusting the three-dimensional mobile platform can realize the contact between the steel ball and the different parts of the cage pocket.

The feature of the torque measuring mechanism is: the ball pocket (7) is bonded to the connecting shaft (6), see Fig. 3, the end face of the connecting shaft is also processed with a tapered hole to ensure that the center of the cage ball pocket is aligned with the axis line, The connecting shaft (6) is connected with the rotating shaft of the air bearing (5), tightened with a set screw to transmit the torque, the other end of the rotating shaft of the air bearing is connected with the torque sensor through a coupling (4), the coupling See Figure 5 for the axle. The torque sensor and the air bearing stator are fixed in the coaxial seat hole support (2). The support is shown in Figure 6. The two holes on the support are coaxial and have a gap of 2 to 3 mm in the horizontal direction. , easy to install and fix parts. the

When assembling, take the upper surface and long side of the base (1) as a reference, ensure that the axis of the seat hole in the support (2) is parallel to the reference side, and ensure that the air-floating linear guide (12) is perpendicular to the reference side And parallel to the datum plane, thereby guaranteeing that the shaft of the motor (10) is parallel to the rotating shaft of the air bearing (5). the

The steel ball (8) contacts the ball pocket (7) to generate radial force and torque due to sliding friction, and the air bearing bears the radial force acting on the ball pocket and transmits the torque to the torque sensor. Based on the readings of the pressure sensor and torque sensor and the eccentricity of the contact (the radius of the inner surface of the ball pocket), the friction coefficient of the contact surface can be calculated. the

Claims (7)

1. the testing device for friction coefficient in a precision bearing ball and retainer pocket hole, comprise load maintainer (I) and torque measuring mechanism (II), it is characterized in that: described load maintainer (I) and torque measuring mechanism (II) are respectively by air supporting line slideway (12) and air-bearing (5) supporting; Load maintainer (I) is tested steel ball (8) and a coupling shaft (9) bonding, this coupling shaft (9) is connected with the rotating shaft of a motor (10), this motor (10) is fixed on one end of air supporting line slideway (12), and the other end of air supporting line slideway (12) is installed a power sensor (14), be fixed on a differential head (16) on a support (15) by worm drive pressure on top surface sensor (14); Differential head (16) passes in the rotating shaft of motor (10) through air supporting line slideway (12) through the pressure of pressure transducer (14), and then is delivered on the surface of contact of steel ball (8) and retainer ball pocket (7); Described torque measuring mechanism (II) is a retainer ball pocket (7) and another root coupling shaft (6) bonding, then be connected with rotating shaft one end of air-bearing (5), this rotating shaft other end is connected with a torque sensor (3) by a shaft coupling (4), and this torque sensor (3) is fixed in the bearing (2) in a coaxial inner conductor seat hole with the stator of air-bearing (5); The moving direction of described air supporting line slideway (12) is perpendicular to motor (10) axis; Motor (10) drives steel ball (8) to rotate, the moment of torsion that steel ball (8) and retainer ball pocket (7) sliding friction produce passes to torque sensor (3) by air-bearing (5), according to the eccentric throw of added pressure, contact position with record moment of torsion and just can calculate the friction factor of surface of contact.

2. the testing device for friction coefficient in precision bearing ball and retainer pocket hole as claimed in claim 1, is characterized in that: described support (15) is fixed on a three-dimensional mobile platform (17) together with air supporting line slideway (12); By three directional trims of three-dimensional mobile platform (17), can realize contacting of steel ball (8) and retainer ball pocket (7) different parts.

3. the testing device for friction coefficient in precision bearing ball and retainer pocket hole as claimed in claim 1, it is characterized in that: described steel ball (8) and coupling shaft (9) bonding, this coupling shaft (9) end face is processed tapered hole, to guarantee the centre of sphere and axial line centering, and bore straight hole to the other end of axle from one end of bellmouth, this hole coordinates with motor shaft, and the processing in axle and hole completes under clamped one time.

4. the testing device for friction coefficient in precision bearing ball and retainer pocket hole as claimed in claim 3, it is characterized in that: described coupling shaft (9) is circumferentially evenly arranged three holding screws with the hole that motor (10) rotating shaft coordinates, to regulate the centering of coupling shaft (9) and motor (10) rotating shaft.

5. the testing device for friction coefficient in precision bearing ball and retainer pocket hole as claimed in claim 1, it is characterized in that: described retainer ball pocket (7) and coupling shaft (6) bonding, the tapered hole of the same processing of end face of this coupling shaft (6), to guarantee retainer ball pocket (7) center and coupling shaft (6) axial line centering, the rotating shaft tight fit connection of the other end of described coupling shaft (6) and air-bearing (5) is with transmitting torque.

6. the testing device for friction coefficient in precision bearing ball and retainer pocket hole as claimed in claim 1, it is characterized in that: described torque sensor (3) is fixed in the bearing (2) in coaxial inner conductor seat hole with air-bearing (5), air-bearing (5) bears radial force the transmitting torque acting on retainer ball pocket (7) like this, and torque sensor (3) only bears moment of torsion; Due to gas suspension, the friction of moment of torsion in transmittance process can be ignored.

7. the testing device for friction coefficient in precision bearing ball and retainer pocket hole as described in claim 1～6, is characterized in that: described three-dimensional mobile platform (17) and bearing (2) are arranged on a sewing platform base (1) above; During assembling, take upper surface and the long limit of pedestal (1) is benchmark, the axis that guarantees seat hole in described bearing (2) is parallel with reference edge, guarantee that described air supporting line slideway (12) is vertical with reference edge and parallel with reference field, thereby guarantee motor (10) rotating shaft and air-bearing (5) shaft parallel.