SU974164A2 - Stand for demonstrating friction forces in threaded joint - Google Patents

Description

The invention relates to educational and laboratory, testing equipment and can be used both in the educational process when studying the course ’’ Details of machines, and in the study of vibrational micro displacements on an inclined plane.

According to the main author. St. No. 284389 known stand for the demonstration of friction in a threaded connection, which contains a base, pivotally connected to it a bar with guide collars, fixing it at a certain angle of inclination of the device and the slider with rollers. At the same time, through the windows are made in the guide collars of the plank through which a support sheet is passed, which, under the influence of an external force, makes a reciprocating movement in the transverse direction relative to the direction of vibration of the slide. The stand allows you to clearly demonstrate the phenomenon of self-unscrewing of threaded joints under alternating loads and vibrations (1].

However, this stand shows vibration displacements realized only due to transverse displacements in the threaded 30 pair under the action of cutting forces and due to radial thinning.

The aim of the invention is to study the influence of conditions on the nature of the self-unscrewing of threaded joints.

The indicated goal is achieved by the fact that the stand is equipped with a slider vibration displacement recorder and its adjustable clamp to the bar.

In this case, the clamp is made in the form of a lever * mounted on a strut with a load-bearing bolt and a spherical heel spring-loaded to the slider, and the vibration displacement recorder is made in the form of a light source, a screen with a scale, and a mirror mounted on the slider.

In FIG. _1 shows a stand, section; figure 2 is the same, a top view; on figs.Z - view A in figure 2.

The stand for demonstrating friction in a threaded connection contains a base 1 (Fig. 1), a strap 2 with a hinge 3 and guide collars 4, a device 5 for fixing the strap at a certain angle of inclination, and a slider with rollers 7. The stand is equipped with a recorder 8 for measuring vibrations the slider 6 and the clamp of the latter to the bar 2. The force of the clamp 9 is directed perpendicular to the plane of the base 1, on which the stand 10 with the hinge 11 (Fig. 3) is made for fixing the clamp. The clamp is made in the form of a lever 12 mounted on a strut with a loading tensbolt 13 and a spherical heel (a spring-loaded rod 14 and a ball 15) to stop against the slider; The vibration displacement recorder 8 is made in the form of a stationary light source 16 (Fig. 2), a scale-screen 17, and a mirror 18 mounted on a slider. In addition, a three-component accelerometer 19 is installed on the slider for registering the vibroperiod. The angle of elevation (прямоугольн of a thread of a rectangular thread (Fig. 1) is installed, the bar is attached to the bracket with the pressure screw 20. On the bar, replaceable shims 21 are installed, which have different materials, roughness, coating, lubrication, etc.

In order to study the effect of loading conditions on the self-unscrewing of threaded joints, strap 2 is set at an elevation angle at which an arbitrary movement of the slide starts down an inclined plane under the action of a weight force, and the static coefficient of friction is determined corresponding to this angle.

The friction forces at this preliminary stage of the experiment correspond to certain specific pressures on the contacting surfaces of the slider b with the plate 21.

Then, the required angle p> is set, corresponding to the angle of the rise of the turns of the pursued threaded pair, and with the help of a tensbolt 13 through the lever 12 and the ball 15, the joint is loaded with the required rated load. · '

The setup of the recorder vibro5 movements is as follows. From the light source, the beam enters the mirror 18, is reflected from it and falls on the scale-screen 17, where the vibrations 10 of the slider b are recorded.

The proposed stand allows you to explore the influence of loading conditions on the self-unscrewing of threaded joints.

Claims (3)

The invention relates to educational laboratory equipment, test equipment and can be used both in the educational process when studying the Machine Parts course, and in the study of vibrating micro-variations on an inclined plane. According to the main author. St. 284389 A stand is well known for demonstrating friction forces in a threaded joint, which contains a base, a bar hinged to it with directions of knuckles, fixing it at a certain angle of inclination, and a slider with rollers. At the same time, through windows, through which the support sheet is passed, are made in the guide shoulders of the strip, making reciprocating movement in the transverse direction relative to the direction of the vibro-vibration of the slider under the influence of an external force. Stemd allows for the demonstration of the phenomenon of Cs1 unscrewing threaded connections with alternating loads and vibrations 1. However, this stand shows the air displacements realized only by transverse displacements in the threaded pair under the influence of pererezayuzhtsyh forces and due to radial thinning. The aim of the invention is to investigate the influence of conditions on the nature of the tightening of threaded connections. This goal achieves that the stand is equipped with a recorder of vibration displacements of the slide and its adjustment by clamping it to the bar. At the same time, the clamp is made in the form of a lever mounted on a rack with load strain-proof bolt and a spherical heel spring-loaded to the slide, and the recorder of vibration displacements is made in the form of a light source, a screen with a scale and a mirror mounted on the slide. FIG. 1 shows a stand, a section; Figure 2 is the same, top view; FIG. 3 is a view A of FIG. 2. FIG. A stand for demonstrating friction forces in a threaded joint contains a base 1 (Fig. 1), a bar 2 with a hinge 3 and guide collars 4, a device 5 for fixing the bar at a certain angle of inclination and a slider with rollers 7. The stand is equipped with a recorder 8 for measuring vibroperiods of the slide 6 and the clamp 9 of the latter to the bar 2. The clamp force 9 is directed perpendicular to the plane of the base 1, on which the stand 10 is made with the hinge 11 (Fig. 3) for fastening the clamp. The clamp is made in the form of a lever 12 mounted on a rack with a load tension bolt 13 and a spherical heel (spring-loaded rod 14 and ball 15) for abutting the slider; The recorder 8 vibrodisplacement made in the form of a stationary light source 16 (Fig. 2), the scale-screen 17 and the mirror 18 mounted on the slide. In addition, a three-component accelerometer 19 is mounted on the slider to register the vibratory overload, the slider. The elevation angle (square turn of the rectangular thread (Fig. 1) is set, the bar is attached to the bracket with a screw 20. The bar is fitted with interchangeable backing plates 21, which have different material, roughness, coating, smooth surface, etc.). loading conditions on the cr # 4 unscrewing of the threaded connections, the strip 2 is set at an elevation angle, at which an arbitrary movement of the slider begins down the inclined plane under the action of a weight force, and the value of the static angle corresponding to this angle is determined. The coefficient of friction. The forces of friction at this preliminary stage of the experiment correspond to certain specific pressures on the contacting surfaces of the slide b with the plate 21. Then set the required angle p / corresponding to the angle of elevation of the turns. and follow the thread pair, and with the help of the strain gauge 13 through The lever 12 and the ball 15 load the joint at the required design load. The vibration displacement recorder is configured as follows. From the light source, the beam hits the mirror 18, is reflected from it and falls on the scale-screen 17, where the vibration of the slide is recorded. B. The proposed bench makes it possible to investigate the effect of loading conditions on the self-unscrewing of threaded connections. Claim 1. Stage for the demonstration of friction force in a threaded joint according to ed. St. No. 284389, characterized in that, in order to study the effect of loading conditions on self-unscrewing of threaded connections, it is equipped with a recorder of vibration displacements of the slide and an adjustable clamping it to the bar. 2. A stand according to claim 1, characterized in that the clamp is made in the form of a lever mounted on a rack with a load strain relief and a spherical heel, spring-loaded to the slide. 3. The stand according to item I, which is also distinguished by the fact that the recorder of vibration displacements is made in the form of a light source, a screen with a scale and a mirror mounted on a slider. Sources of information taken into account in the examination 1. USSR author's certificate 284389, cl. G 01 L 7/00, 06/18/69. 17  / / ABOUT cf  / / + + 4 .2 v