An experimental device for studying the vibration characteristics of a pin-slot variable cell motion pair gap

Abstract

The application discloses an experimental device for researching the influence of a pin-slot variable-cell motion pair gap on the vibration characteristics of a variable-cell mechanism, which comprises a mechanism composed of a crank provided with cylindrical pins with different diameters, a rocker with a sliding slot and a sliding block, and an adjustable spring connected with the sliding block and providing a spring constraint force with a proper size, the crank is driven by a servo motor and is installed on a base, the rocker and the crank are connected through a pin-slot pair, the rocker is connected with the sliding block through a rotating pair, the sliding block moves in a sliding way installed on a rack and is constrained by the spring force of the adjustable spring, the spring force of the adjustable spring is adjusted so that the sum of the spring force and the static friction force of the track on the sliding block is greater than the acting force of the rocker on the sliding block when the cylindrical pin moves in the sliding slot, so that the sliding block is kept static, and the vibration test system of the mechanism is composed of an acceleration sensor, a strain gauge and a data acquisition device.

Description

TECHNICAL FIELD

[0001] The present application relates to an experimental device for studying the vibration characteristics of a pin-slot metamorphic pair. BACKGROUND

[0002] Metamorphic mechanisms have the advantages of variable topological structure and variable degrees of freedom, and can meet the requirements of multiple working conditions and multiple tasks. In particular, they have good application prospects in aerospace, robots, medical devices, manufacturing systems, special excavators under special working conditions, etc. The number of constraints provided by the metamorphic pair in the metamorphic mechanism or the properties of the pair are variable under certain conditions, and the dynamics performance is much more complex than that of ordinary pairs with fixed constraints. The established theories for fixed constraint pairs, such as clearance vibration theory, cannot adapt to metamorphic pairs, but the vibration performance of metamorphic pair clearances has not been studied. The practical application of metamorphic mechanisms, especially the long-term lag of mature products in theoretical achievements, has not met expectations so far, and the neglect of the dynamics of metamorphic pairs is an important reason. Studying the vibration theory of metamorphic pairs with clearances is also an urgent need to make metamorphic mechanisms practically applicable in engineering practice. The pin-slot metamorphic pair is a typical metamorphic pair, and its metamorphic principle and process are simple and clear, making it an ideal object for studying the impact of metamorphic pair clearances on mechanism vibration performance. The present application is an experimental device for studying the impact of the clearance between the pin and the slot of a pin-slot metamorphic pair on the vibration of the mechanism. By changing the size of the clearance between the pin and the slot, the corresponding change in the mechanism vibration response can be used to study the relationship between the clearance of the relevant pin-slot metamorphic pair and the mechanism vibration response, as well as the characteristics of nonlinear resonance, motion stability, and chaotic phenomena of the mechanism. SUMMARY

[0003] To solve the technical problems in the prior art, the present application provides the following technical solutions.

[0004] The first aspect of the present application provides an experimental device for studying the influence of the pin-slot variable-cell kinematic pair gap on the vibration characteristics of the variable-cell mechanism, which comprises a mechanism composed of a crank with different diameter cylindrical pins installed at the ends, a rocker with a sliding slot, and a slider, and an adjustable spring connected with the slider, the adjustable spring provides a proper size of spring constraint force to ensure that the slider remains stationary when the cylindrical pin slides in the rocker sliding slot, and the slider can move against the spring force under the action of the rocker when the cylindrical pin rotates at the end of the rocker sliding slot, the crank is driven by a servo motor and is installed on a base, the rocker and the crank are connected through a pin-slot pair, the rocker is connected with the slider through a rotary pair, the slider moves in a sliding track installed on a rack and is constrained by the spring force of the adjustable spring; the spring force of the adjustable spring is adjusted so that the sum of the spring force and the static friction of the track to the slider is greater than the force of the rocker pushing the slider when the cylindrical pin moves in the sliding slot, so that the slider remains stationary. When the cylindrical pin reaches the end of the slot and no longer slides but rotates, the sum of the spring force and the friction between the slider and the sliding track is less than the horizontal component of the force of the rocker on the slider, and the slider moves. The vibration test system of the mechanism is composed of an acceleration sensor, a strain gauge, and a data acquisition device.

[0005] Preferably, the base of the pin-slot variable-cell kinematic pair mechanism is fixed on a platform;

[0006] The resistance adjusting mechanism is composed of two compression springs with different stiffness, adjusting nuts, and adjusting springs installed at both ends of the slider, passing through the guide rod, and the adjusting nuts are assembled at both ends of the spring, and the spring can be contracted by rotating the pre-tightening nut;

[0007] The power device is driven by a servo motor.

[0008] Preferably, the pin-slot variable-cell kinematic gap can be freely adjusted, and the diameter of the cylindrical pin can be 39.0 mm, 39.1 mm, 39.2 mm, 39.3 mm, 39.5 mm, 39.7 mm, or 39.9 mm.

[0009] Preferably, the spring force of the adjustable spring can be adjusted arbitrarily, or only the spring force at one end can be adjusted.

[0010] Preferably, the mechanism is driven by a servo motor, and the speed of the servo motor can be adjusted within 0-100 r / min.

[0011] The second aspect of the present application provides a vibration test function of the experimental device for studying the influence of the pin-slot variable-cell kinematic pair gap on the vibration characteristics of the variable-cell mechanism, which comprises the following steps and control technical conditions:

[0012] (1) An acceleration sensor is installed on the upper surface of the rocker;

[0013] (2) A strain gauge is attached to the side surface of the rocker;

[0014] (3) Put the data acquisition device on the base, and connect the wires;

[0015] (4) Adjust the compression amount of the spring, the rotating speed of the servo motor, and the different angles of the rocker arm, and determine the parameters such as the acceleration and stress strain of the testing system. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a physical diagram of the pin-slot metamorphic pair gap vibration characteristic experimental device;

[0017] Figure 2 It is a structural schematic diagram of the pin-slot metamorphic pair gap vibration characteristic experimental device;

[0018] Figure 3 It is a diagram of the pin-slot metamorphic pair mechanism. DETAILED DESCRIPTION

[0019] The physical diagram and the structural schematic diagram of the pin-slot metamorphic pair gap vibration characteristic experimental device are shown in Figures 1-2 , Figure 3 It is a diagram of the pin-slot metamorphic mechanism.

[0020] The working principle of the pin-slot metamorphic mechanism is shown in Figure 3 . In the metamorphic mechanism, the components 1 and 2 are connected by the pin-slot metamorphic pair, the components 2 and 3 are connected by the rotating pair, the component 3 and the rack are connected by the moving pair, and the component 3 is also constrained by the additional spring force. The pin-slot metamorphic pair is a variable constraint pair. When the cylindrical pin is at the two ends A and B of the slot, it is equivalent to a rotating pair, and the pin-slot metamorphic pair has two constraints at this time. When the cylindrical pin is at any position between the two ends of the slot, it is equivalent to a moving pair, and the pin-slot metamorphic pair only provides one constraint at this time.

[0021] The metamorphic mechanism has two configurations. Configuration 1: When the cylindrical pin slides between the two ends A and B of the slot, the slider 3 remains stationary under the constraint of the spring force, and the components 1 and 2 rotate around the fixed point. When the cylindrical pin reaches the end A or B of the slot, the cylindrical pin no longer moves relative to the slot, and rotates at the end of the slot and drives the component 2 to move in the plane. The component 3 moves under the force of the component 2, overcoming the spring force. The size of the elastic force is set according to the force gradient requirement of the metamorphic mechanism, that is, to ensure that when the cylindrical pin on the component 1 slides in the slot of the component 2, the component 3 (slider) remains stationary under the action of the spring force. When the cylindrical pin on the component 1 reaches the end of the slot of the component 2 and no longer slides but rotates, the component 3 can move against the spring force. When the cylindrical pin moves in the slot again, the component 3 can remain stationary under the action of the spring force.

[0022] For pin-slot metamorphic pair, the test cylinder pin with different diameters is used to change the clearance of pin-slot metamorphic pair as moving pair and rotating pair.

[0023] As shown in Figure 2 The pin-slot metamorphic pair mechanism is composed of fixed base 1, guide rod support 2, adjusting spring 3, slider rail base mounting plate 4, adjusting spring 5, slider 6, adjusting nut 7, slider rail 8, acceleration sensor 9, rocker 10, crank 11, motor fixed support 12, servo motor 13, cylindrical pin 14, strain gauge 15, data acquisition device 16, etc. The crank 11 makes rotational motion under the drive of the servo motor 13, and the cylindrical pin 14 installed on the crank 11 drives the rocker 10 to rotate, while the cylindrical pin 14 slides in the groove of the rocker 10. When the cylindrical pin slides to the end of the groove, it cannot continue to slide, but rotates at the end of the groove. At this time, the rocker 10 pushes the slider 6 to move against the spring resistance of the adjusting spring 5. When the cylindrical pin continues to slide away from the end of the sliding groove, the slider moves back to the equilibrium position under the action of the spring force, and the rocker 10 continues to rotate.

[0024] Here, in order to make the pin-slot metamorphic pair mechanism realize the motion law required by the motion cycle diagram, the spring resistance of the adjusting spring 5 needs to meet the resistance gradient requirement of the metamorphic pair, that is, when the cylindrical pin 14 slides in the groove of the rocker 10, the spring force of the adjusting spring 5 can keep the slider 6 stationary. When the cylindrical pin slides to the end A or B of the groove of the rocker, the slider 6 can move against the spring resistance of the adjusting spring 5 under the action of the rocker 10.

[0025] The Figure 2 acceleration sensor 9 and strain gauge 15 installed on the rocker 10 collect the vibration signals of the mechanism.

[0026] The experimental device obtains different clearances of pin-slot metamorphic pairs by replacing cylindrical pins 14 with different diameters. The relationship between the clearance of the pin-slot metamorphic pair and the vibration response of the mechanism is obtained from the corresponding mechanism vibration signals under different pin-slot metamorphic pair clearances, and the influence of the clearance of the metamorphic pair on various vibration characteristics of the mechanism is further studied.

Claims

1. An experimental device for studying the influence of the pin-slot pair clearance on the vibration characteristics of a metamorphic mechanism, comprising a mechanism composed of a crank with cylindrical pins of different diameters and a rocker with a sliding slot and a slider, and an adjustable spring coupled to the slider, which provides a spring constraint force of appropriate size to ensure that the slider remains stationary when the cylindrical pins slide in the rocker sliding slot, and the slider can move against the spring force under the action of the rocker when the cylindrical pins rotate at the ends of the rocker sliding slot, characterized in that: The crank is driven by a servo motor and is installed on a base, the rocker and the crank are connected by a pin-slot pair, the rocker is connected with the slider through a rotary pair, the slider moves in a slide installed on a rack and is constrained by the spring force of an adjustable spring; the spring force of the adjustable spring is adjusted so that when the cylindrical pin moves in the slot, the sum of the spring force and the static friction of the track on the slider is greater than the force of the rocker pushing the slider, so that the slider remains static; when the cylindrical pin reaches the end of the slot and no longer slides but rotates, the sum of the spring force and the friction between the slider and the slide is less than the horizontal component of the force of the rocker on the slider, the slider moves, and the vibration test system of the mechanism is composed of an acceleration sensor, a strain gauge and a data acquisition device; ​ The base of the pin-slot variable cell motion pair mechanism is fixed on a platform; The resistance adjusting mechanism is composed of two compression springs with different stiffness and adjusting nuts, the adjusting springs are installed at both ends of the slider, pass through the guide rod, and the adjusting nuts are assembled at both ends of the springs, the springs can be shrunk by rotating with the pre-tightening of the nuts; The power device is driven by a servo motor.

2. The experimental device for studying the influence of the pin-slot cell kinematic pair gap on the vibration characteristics of the metamorphic mechanism according to claim 1, characterized in that: The pin-slot variable cell motion gap can be freely adjusted, and the diameter of the cylindrical pin can be 39.0mm, 39.1mm, 39.2mm, 39.3mm, 39.5mm, 39.7mm or 39.9mm.

3. The experimental device for studying the influence of the clearance between the cell-changing mechanism and the cell-changing motion pair on the vibration characteristics of the cell-changing mechanism according to claim 1, characterized in that: The spring force of the adjustable spring can be adjusted arbitrarily, or only the spring force of one end can be adjusted.

4. The experimental device for studying the influence of the clearance between the cell-changing mechanism and the cell-changing motion pair on the vibration characteristics of the cell-changing mechanism according to claim 1, characterized in that: The mechanism is driven by a servo motor, and the speed of the servo motor can be adjusted within 0-100r / min.

5. The experimental device for studying the influence of the clearance between the cell-changing mechanism and the cell-changing motion pair on the vibration characteristics of the cell-changing mechanism according to claim 1, characterized in that, The vibration test includes the following steps: (1) install an acceleration sensor on the upper surface of the rocker; (2) paste a strain gauge on the side surface of the rocker; (3) place a data acquisition device on the base and connect the wires; (4) adjust the compression amount of the spring, the speed of the servo motor and different angles of the rocker, and measure the acceleration and stress-strain parameters of the mechanism through the test system.

Images