CN103743668A - Device and method for testing lateral impact friction - Google Patents

Abstract

The invention discloses a side impact friction test device and a test method. The side impact friction factor test device includes an air pump, a pneumatic impact device, an arc track, an incident rod, a fixture, a support, a small wheel, and an acceleration sensor. , a speed sensor, a first strain gauge, a second strain gauge, a first sample, a second sample, a transmission rod, a pulley, a shock absorber, a belt, a variable frequency motor, a signal acquisition device and a computer. The pneumatic impact device and the small wheel at the bottom of the support can move on the arc track to adjust the incident angle of the impact of the sample. The invention can realize the measurement of side impact friction between materials; the shape of the sample used in the invention can be changed, and can realize the measurement of side impact friction characteristics between different types of materials.

Description

A side impact friction test device and test method

technical field

The invention relates to a side impact friction testing device and a testing method, in particular to a device and method capable of directly measuring impact force, impact torque, impact velocity, impact acceleration and friction factor during material side impact.

Background technique

Impact friction is surface friction caused by the dynamic impact of two solid surfaces. In various types of machinery, many parts are subjected to different degrees of impact and friction. For example, during the working process of a ball mill in the coal mine field, there are dynamic side impact frictions between steel balls, rollers, and materials. The test device for the impact friction characteristics of materials during side impact has not yet been found, which brings great inconvenience to the side impact friction test.

Therefore, it is necessary to develop a device that is easy to operate and can directly measure the impact friction characteristics of the material surface during side impact, so as to provide an experimental method for better evaluation of the material side impact friction characteristics.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention proposes a device and method capable of directly measuring the side impact friction characteristics of materials.

The technical scheme that the present invention takes for solving the problems of the technologies described above is:

A side impact friction test device, said side impact friction coefficient test device includes an air pump (01), a pneumatic impact device (02), an arc track (03), an incident rod (04), a fixture (05), Support (06), small wheel (07), acceleration sensor (08), speed sensor (09), first strain gauge (10), second strain gauge (11), first sample (12), second Sample (13), transmission rod (14), pulley (15), shock absorber (16), belt (17), frequency conversion motor (18), signal acquisition device (19) and computer (20); incidence rod ( 04) and the support (06) are connected by a sliding bearing so that the incident rod (04) can move in the axial and circumferential directions; the transmission rod (14) and the support (06) are connected by a rolling bearing, and the pneumatic impact device (02) and the incident The rods (04) are coaxial, the incident rod (04) and the transmission rod (14) are not coaxial, and the two axes have an angle θ; the bottom of the pneumatic impact device (02) and the support (06) supporting the incident rod is equipped with a The wheel (07) can move on the arc-shaped track (03) to adjust the incident angle θ of the impact of the first sample (12); the track is equipped with a fixture (05) to fix the position of the small wheel to ensure that the side impact process The angle of incidence is constant; the angle between the section of the first sample (12) connected to the incident rod (04) and the axial direction needs to be processed to 90°-θ; the section of the second sample (13) is sufficient to cover the first sample The section of (12); on the incident rod (04), there are accelerometer (08), speed sensor (09), first strain gauge (10), second strain gauge (11) with magnetism successively from left to right; The acceleration sensor (08) and the speed sensor (09) are used to measure the acceleration and velocity of the side impact of the first sample (12) respectively; the first strain gauge (10) is used to measure the positive strain of the side impact friction process of the sample, The second strain gauge (11) is used to measure the shear strain during the frontal impact friction of the sample; the first strain gauge (10) is close to the left side of the incident rod (04), and the second strain gauge (11) is close to the incident rod (04 ), used to improve the accuracy of the measurement results.

In the described side impact friction test device, the ends of the incident rod (04) and the transmission rod (14) can be connected to the first sample (12) of various shapes including circular and annular through surface connection. 1. Different forms of side impact friction pairs composed of the second sample (13).

In the side impact friction test device, four screws are screwed on the end cylindrical surfaces of the incident rod (04) and the transmission rod (14) to prevent the axial loosening of the first sample (12) and the second sample (13). .

In the said side impact friction testing device, the angular velocity of the transmission rod (14) can be adjusted by adjusting the rotational speed of the variable frequency motor (18).

In the side impact friction testing device, there is a gap of 1-3mm between the first sample (12) and the second sample (13), so as to simulate the side impact process.

In the side impact friction testing device, some lubricants may also be applied to the cross-sectional surfaces of the first sample (12) and the second sample (13) to simulate wet friction conditions.

In the described side impact friction testing device, a gap of 1-3 mm is provided between the right end of the transmission rod (14) and the shock absorber (16), and the shock absorber (16) can reduce the friction of the transmission rod (14) in the impact process. Shock and impact on bearings.

A side impact friction test method is illustrated by taking a circular impact surface as an example. Qiao and Qiao represent the minor diameter and major diameter of the circular ring respectively, comprising the following steps:

1) Before the experiment, a certain polishing pretreatment should be done on the surface of the friction pair of the sample to make the surface roughness reach Ra=0.07 μm, so as to determine whether relative sliding occurs during side impact and whether there is dynamic friction.

2) Install the first sample (12) and the second sample (13), start the frequency conversion motor (18), the pneumatic impact device (02) impacts the incident rod (04), and the signal acquisition device records the acceleration sensor (08) during the experiment ), the velocity sensor (09), the first strain gauge (10) and the second strain gauge (11); the first strain gauge (10) measures the positive strain ε, and the second strain gauge (11) measures the shear strain γ ;

3) The impact velocity and acceleration are directly measured by the velocity sensor and the acceleration sensor; the impact force, impact torque and friction factor are derived through the formulas of positive strain ε and shear strain γ; Deduce and fit the change curves of impact force, impact torque, impact velocity, acceleration and friction factor during frontal impact;

Normal stress of the incident rod: σ=Eε, where E represents the elastic modulus of the incident rod;

Surface shear stress of the incident rod: τ=Gγ, where G represents the shear modulus of the incident rod;

Impact force: F=σA, where A=πR ² , R represents the radius of the incident rod;

其中

τ表示入射杆表面切应力，I_R表示入射杆横截面对圆心的极惯性矩；Impact torque:

in

τ represents the shear stress on the surface of the incident rod, and I _R represents the polar moment of inertia of the cross section of the incident rod to the center of the circle;

The friction factor is derived from the following theoretical formula through the normal strain ε and shear strain γ:

其中

S_a表示试样冲击截面面积；The normal stress of the impact section of the sample:

in

S _a represents the impact cross-sectional area of the sample;

其中

τ_r表示冲击截面上距圆心为r的任意点的切应力，I_a表示试样冲击横截面对圆心的极惯性矩；The average shear stress of the impact section of the sample:

in

τ _r represents the shear stress at any point r from the center of the circle on the impact section, and I _a represents the polar moment of inertia of the impact cross section of the sample to the center of the circle;

The average shear stress on the sample is equal to the friction force, and the friction factor is:

The beneficial effects of the invention are: the invention can realize the measurement of side impact friction between materials; the shape of the sample used in the invention can be changed, and the measurement of side impact friction characteristics between different types of materials can be realized.

Description of drawings

Fig. 1 is a schematic structural view of the side impact friction testing device of the present invention.

Fig. 2 is a detailed view of the connection between the end of the incident rod (04) and the transmission rod (14) and the sample in Fig. 1 .

Fig. 3 is a structural schematic diagram of the first sample (12) and the second sample (13).

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments.

Please refer to Figure 1 and Figure 2, a side impact friction test device, including air pump 01, pneumatic impact device 02, arc-shaped track 03, incident rod 04, support 06, acceleration sensor 08, speed sensor 09, the first Strain gauge 10, second strain gauge 11, first sample 12, second sample 13, transmission rod 14, pulley 15, shock absorber 16, belt 17, frequency conversion motor 18, computer 20 and signal acquisition device 19; The rod 04 and the support 06 are connected by a sliding bearing so that the incident rod 04 can move in the axial and circumferential directions; the transmission rod 14 and the support 06 are connected by a rolling bearing, the pneumatic impact device 02 and the incident rod 04 are coaxial, and the incident rod 04 and the transmission rod 04 are connected by a rolling bearing. The rods 14 are not coaxial, and the two axes have an included angle θ; the bottom of the pneumatic impact device 02 and the support 06 supporting the incident rod is equipped with a small wheel 07, which can move on the arc-shaped track 03 to adjust the impact of the first sample 12 Incidence angle θ; fixture 05 is installed on the track to fix the position of the small wheel to ensure a constant incident angle during side impact; the angle between the cross section and the axial direction of the first sample 12 connected to the incident rod 04 needs to be processed to 90° -θ; the section of the second sample 13 sufficiently covers the section of the first sample 12 . The incident rod 04 is attached with a magnetic acceleration sensor 08, a velocity sensor 09, a first strain gauge 10, and a second strain gauge 11 from left to right; the acceleration sensor 08 and the velocity sensor 09 are respectively used to measure the first sample 12 Acceleration and velocity of side impact; the first strain gauge 10 is used to measure the positive strain of the sample side impact friction process, and the second strain gauge 11 is used to measure the shear strain of the sample front impact friction process; the first strain gauge 10 Close to the left side of the incident rod 04, the second strain gauge 11 is close to the right side of the incident rod 04 to improve the accuracy of the measurement results; there is an appropriate gap of 1-3mm between the first sample 12 and the second sample 13 , in order to simulate the side impact process. The external dimensions of the ends of the incident rod 04 and the transmission rod 14 are exactly the same. The circular section at the end is provided with a square hole, and four threaded holes are evenly distributed around the cylindrical section of the pressure rod, and four bolts 21 are used to clamp and fix the sample, preventing the first sample 12 and the second sample from being impacted by the side. The axial looseness of the second sample 13. The shapes of the first sample 12 and the second sample 13 are shown in FIG. 3 , and different forms of side impact friction pairs can be simulated according to the joint shape of the samples.

By adjusting the impact strength of the pneumatic impact device 02, load the incident rod 04 with different strengths, measure the pressure intensity of the incident rod 04 through the first strain gauge 10, and quantitatively simulate and analyze the side impact friction of different strengths of the experimental materials; adjust the frequency conversion motor 18 Rotate speed to adjust different initial relative speeds to simulate different actual working conditions. The shock absorber 16 can reduce the vibration of the transmission rod 14 and the impact on the bearing during impact.

Please refer to FIG. 1 , the incident rod 04 and the transmission rod 14 are respectively supported by two supports 06 evenly distributed to increase the stability of the compression rod during the experiment and reduce the error of the experimental result.

The impact velocity and impact acceleration are directly measured by the velocity sensor and acceleration sensor; the impact force and impact torque are derived from the following theory through the positive strain ε and shear strain γ (take the circular impact surface on the upper left in Figure 3 as an example, r ₁ and r ₂ represent the minor diameter and major diameter of the circular ring respectively):

Normal stress of the incident rod: σ=Eε (where E represents the modulus of elasticity of the incident rod)

Surface shear stress of the incident rod: τ=Gγ (where G represents the shear modulus of the incident rod)

Impact force: F=σA (where A=πR ² , R represents the radius of the incident rod)

(其中

τ表示入射杆表面切应力，I_R表示入射杆横截面对圆心的极惯性矩)Impact torque:

(in

τ represents the shear stress on the surface of the incident rod, I _R represents the polar moment of inertia of the cross section of the incident rod to the center of the circle)

The friction factor is derived from the following theoretical formula through the normal strain ε and shear strain γ:

(其中

S_a表示试样冲击截面面积)The normal stress of the impact section of the sample:

(in

S _a represents the impact cross-sectional area of the sample)

(其中

τ_r表示冲击截面上距圆心为r的任意点的切应力，I_a表示试样冲击横截面对圆心的极惯性矩)；The average shear stress of the impact section of the sample:

(in

τ _r represents the shear stress at any point on the impact section that is r away from the center of the circle, I _a represents the polar moment of inertia of the impact cross section of the sample to the center of the circle);

The average shear stress on the sample is equal to the friction force, and the friction factor is:

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the present invention.

Claims (8)

1. A side impact friction tester, characterized in that: the side impact friction factor tester comprises an air pump (01), a pneumatic impact device (02), an arc track (03), an incident rod (04), Fixture (05), support (06), small wheel (07), acceleration sensor (08), speed sensor (09), first strain gauge (10), second strain gauge (11), first sample (12), second sample (13), transmission rod (14), pulley (15), shock absorber (16), belt (17), frequency conversion motor (18), signal acquisition device (19) and computer ( 20); the incident rod (04) and the support (06) are connected by a sliding bearing so that the incident rod (04) can move in the axial and circumferential directions; the transmission rod (14) and the support (06) are connected by a rolling bearing, and the pneumatic impact The device (02) and the incident rod (04) are coaxial, the incident rod (04) and the transmission rod (14) are not coaxial, and the two axes have an included angle θ; the pneumatic impact device (02), the support for supporting the incident rod ( 06) The bottom is equipped with a small wheel (07) that can move on the arc-shaped track (03) to adjust the incident angle θ of the impact of the first sample (12); the track is equipped with a fixture (05) to fix the position of the small wheel , to ensure a constant incident angle during side impact; the angle between the section of the first sample (12) connected to the incident rod (04) and the axial direction needs to be processed to 90°-θ; the section of the second sample (13) Enough to cover the cross-section of the first sample (12); the incident rod (04) is sequentially attached with a magnetic acceleration sensor (08), a velocity sensor (09), a first strain gauge (10), a second The strain gauge (11); the acceleration sensor (08) and the velocity sensor (09) are used to measure the acceleration and velocity of the side impact of the first sample (12) respectively; the first strain gauge (10) is used to measure the side impact friction of the sample The positive strain of the process, the second strain gauge (11) is used to measure the shear strain in the frontal impact friction process of the sample; the first strain gauge (10) is close to the left side of the incident rod (04), the second strain gauge (11 ) is close to the right side of the incident rod (04), which is used to improve the accuracy of the measurement results. 2. The side impact friction testing device as claimed in claim 1, characterized in that: the ends of the incident rod (04) and the transmission rod (14) can be connected by a profiled surface connection including a circular, circular ring. Different forms of side impact friction pairs composed of the first sample (12) and the second sample (13) of different shapes. 3. The side impact friction testing device as claimed in claim 1, characterized in that: four screws are screwed on the end cylindrical surface of the incident rod (04) and the transmission rod (14) to stop the first sample (12), the second The axial looseness of the second sample (13). 4. The side impact friction testing device according to claim 1, characterized in that: the angular velocity of the transmission rod (14) can be adjusted by adjusting the rotational speed of the frequency conversion motor (18). 5. The side impact friction testing device according to claim 1, characterized in that there is a gap of 1-3mm between the first sample (12) and the second sample (13), so as to simulate the side impact process. 6. The side impact friction testing device according to claim 1, characterized in that: some lubricants can also be applied to the cross-sectional surfaces of the first sample (12) and the second sample (13) to simulate wet friction conditions. 7. The side impact friction testing device as claimed in claim 1, characterized in that: a gap of 1-3mm is provided between the right end of the transmission rod (14) and the shock absorber (16), and the shock absorber (16) can absorb The vibration of the transmission rod (14) and the impact on the bearing during the small impact. 8. A side impact friction test method is illustrated by taking a circular impact surface as an example, r ₁ and r ₂ represent the minor diameter and major diameter of the circular ring respectively, and it is characterized in that it comprises the following steps: 1) Before the experiment, a certain polishing pretreatment should be done on the surface of the friction pair of the sample to make the surface roughness reach Ra=0.07μn, so as to determine whether relative sliding occurs during side impact and whether there is dynamic friction. 2) Install the first sample (12) and the second sample (13), start the frequency conversion motor (18), the pneumatic impact device (02) impacts the incident rod (04), and the signal acquisition device records the acceleration sensor (08) during the experiment ), the velocity sensor (09), the first strain gauge (10) and the second strain gauge (11); the first strain gauge (10) measures the positive strain ε, and the second strain gauge (11) measures the shear strain γ ; 3) The impact velocity and acceleration are directly measured by the velocity sensor and the acceleration sensor; the impact force, impact torque and friction factor are derived through the formulas of positive strain ε and shear strain γ; Deduce and fit the change curves of impact force, impact torque, impact velocity, acceleration and friction factor during frontal impact; Normal stress of the incident rod: σ=Eε, where E represents the elastic modulus of the incident rod; Surface shear stress of the incident rod: τ=Gγ, where G represents the shear modulus of the incident rod; Impact force: F=σA, where A=πR ² , R represents the radius of the incident rod; Impact torque: in

τ represents the shear stress on the surface of the incident rod, and I _R represents the polar moment of inertia of the cross section of the incident rod to the center of the circle; The friction factor is derived from the following theoretical formula through the normal strain ε and shear strain γ: The normal stress of the impact section of the sample: in

S _a represents the impact cross-sectional area of the sample; The average shear stress of the impact section of the sample:

in

τ _r represents the shear stress at any point r from the center of the circle on the impact section, and I _a represents the polar moment of inertia of the impact cross section of the sample to the center of the circle; The average shear stress on the sample is equal to the friction force, and the friction factor is:

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