CN213684758U

CN213684758U - Device for reducing static friction influence in triaxial test

Info

Publication number: CN213684758U
Application number: CN202022399749.1U
Authority: CN
Inventors: 桑勇; 孔宪京; 邹德高; 王意宾; 刘京茂; 周晨光
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2020-10-26
Filing date: 2020-10-26
Publication date: 2021-07-13
Anticipated expiration: 2030-10-26

Abstract

The utility model provides a reduce device of static friction influence among the triaxial test belongs to the mechanical engineering field. The lower part of a piston rod in the device goes deep into a cylinder body through a sliding sleeve, and a sealing ring and a buffer sleeve are sleeved between the lower part of the piston rod and a piston, so that the threaded bushing, the buffer sleeve, the piston and the piston rod form an organic whole. A servo motor is arranged on the right side of the hydraulic cylinder, a pair of meshed helical gears are driven below the hydraulic cylinder, and the rotary driving force of the servo motor is transmitted to the piston rod through the transmission of the motion of the helical gears. A thrust bearing is arranged below the piston rod; the lower end of the spring is used for placing a load; the piston rod moves up and down and also rotates under the action of the servo motor. The utility model discloses a key point is the rotary motion of piston, compares in the simple up-and-down reciprocating motion before, including behind the rotary motion, the sliding friction can be converted into to the stiction between piston and the cylinder body wall, can reduce the influence of frictional force to whole experimental equipment greatly, finally reaches good control effect.

Description

Device for reducing static friction influence in triaxial test

Technical Field

The utility model belongs to the mechanical engineering field relates to soil mechanics triaxial test, especially a reduce device of static friction influence.

Background

A triaxial tester is frequently used for measuring the strength and deformation of soil, has wide application range, and can be used for measuring various parameters including shear strength characteristics, consolidation characteristics and soil permeability. The triaxial tester usually adopts the mode of electro-hydraulic servo loading, and the axial loading force needs to be set according to the magnitude of confining pressure in the experimental process. The electro-hydraulic servo loading hydraulic cylinder is generally composed of a piston, a connecting rod, a cylinder body, a seal and the like. In the electro-hydraulic servo control system of the triaxial test, the friction force between a hydraulic cylinder piston and a cylinder body, between a piston rod and a bearing bush and between a loading rod and a pressure chamber is larger, so that the stability and the tracking precision of the system are seriously influenced. Many scholars have also adopted various methods to improve the problems caused by friction, such as improving the surface condition of the contact surfaces, increasing the lubrication degree of the contact surfaces, adopting various friction compensation techniques, etc.

However, increasing the machining accuracy improves the surface condition of the contact surfaces, is extremely costly, and cannot be subjected to lateral forces to damage the machined surfaces. The lubrication degree of the contact surface is improved, and the polytetrafluoroethylene seal is generally adopted, so that the influence of friction force is reduced. Various friction compensation techniques do reduce the effects of friction, but do not significantly reduce the effects of friction. In addition, the mode of increasing vibration excitation is often adopted in engineering, the influence of friction is reduced, however, the vibration excitation mode can generate great noise, high-frequency disturbance can be generated on a sample, and the experiment is not facilitated. At present, there is a need for a device that achieves low cost and is easy to retrofit old equipment, effectively reducing the effects of friction.

SUMMERY OF THE UTILITY MODEL

The utility model aims at reducing the influence of frictional force among the electric liquid servo by a wide margin, in order to solve this problem, the utility model provides a mechanism device that hydraulic cylinder piston rod can slowly at the uniform velocity rotatory, in the piston rod reciprocating up-and-down motion process, servo motor passes through the gear and drives the piston rod and be rotary motion to convert the static friction of piston rod and cylinder body into sliding friction, sliding friction is much less than static friction, thereby reduces the influence of frictional force among the electric liquid servo by a wide margin.

In order to achieve the above purpose, the utility model discloses a technical scheme is:

a device for reducing static friction influence in a triaxial test comprises a motor guide rail, a servo motor, a bevel pinion, a load, a spring, a thrust bearing, a nut fastening device A, an oil outlet, the inner wall of a cylinder body, a plunger sealing element (A type), an O-shaped sealing ring, an oil inlet, a loop bar sealing element, a cleaning ring, a sliding bearing, an integral support, a nut fastening device B, a threaded bushing, a throttle valve, a buffer sleeve A, a piston, a buffer sleeve B, a piston rod, a check valve with an exhaust function, a flange and a bevel pinion.

The integral support is of a frame structure and plays a role in integral supporting and fixing; the top of the motor guide rail is arranged on the top frame of the integral bracket and is positioned on the right side; the load is placed on the bottom frame of the unitary support.

The lower part of the piston rod is connected with the piston through a sliding sleeve which extends into the cylinder body, a sealing ring and a buffer sleeve A are sleeved between the lower part of the piston rod and the piston, the threaded bushing is fixedly connected to the periphery of the buffer sleeve A, and the threaded bushing, the buffer sleeve B and the buffer sleeve A provide restraint force in the vertical direction for the piston, so that the threaded bushing, the buffer sleeve A, the buffer sleeve B, the piston and the piston rod form an organic whole which can do up-and-down reciprocating motion in the cylinder body. Piston lateral wall and cylinder body inner wall are through the sealed close contact of A type plunger, and the sealed constraining force that can make the piston receive the horizontal direction of A type plunger, and threaded bush, cushion collar A and B that set up on the piston rod can make piston and piston rod receive the constraining force of vertical direction.

The flange is arranged above the cylinder body, is in contact with the piston rod through a loop bar sealing element and fastens the upper half part of the cylinder body, and an O-shaped sealing ring is arranged between the flange and the piston rod and used for sealing the reciprocating motion; the cleaning ring is positioned above the flange and used for filtering impurities in the hydraulic oil to play a role in purifying the hydraulic oil; and a plurality of nut fastening devices A, B which are uniformly distributed are arranged below the cylinder body and fasten the lower end cover and the lower half part of the inner wall of the cylinder body together.

The oil inlet is arranged above the hydraulic cylinder and used for flowing high-energy hydraulic oil into the cylinder body from the outside, the high-energy hydraulic oil pushes the piston to move downwards under the action of hydraulic energy and is converted into low-energy hydraulic oil when flowing to the lower part of the cylinder body, then the low-energy hydraulic oil flows out from the oil outlet, and the piston rod are driven to do reciprocating motion up and down by the repeated circulation of the hydraulic oil. The oil outlet is arranged below the side wall of the cylinder body and communicated with the inner cavity of the cylinder body.

The right side of the hydraulic cylinder is provided with a servo motor, the right side of the servo motor is fixed on a motor guide rail, the servo motor can reciprocate up and down along the motor guide rail, the lower output end of the servo motor is connected with a pair of meshed helical gears through a flat key, the large helical gear and the small helical gear are also connected with the piston rod through the flat key, and the rotary driving force of the servo motor is transmitted to the piston rod through the transmission of the motion of the helical gears, so that the piston rod is driven to rotate. The flat key has the advantages of large bearing torque, long service life, good guidance quality and the like under the same shaft diameter; in consideration of the problems of stability, bearing capacity and the like in the motion transmission process, a helical gear with a helical angle of 30 degrees is adopted as a mechanism for transmitting the motion and the power.

A sliding bearing is arranged above the piston rod and comprises four parts, namely a shaft diameter, a bearing bush, a bearing seat and a bearing cover, the bearing cover and the bearing seat are connected through a stud, the joint surface of the bearing cover and the bearing seat is positioned by a pin, and gaskets with different thicknesses are placed to adjust the bearing gap; the shaft diameter is arranged in a small section groove of the piston rod, the bearing bush is sleeved on the shaft diameter, when the piston rod moves up and down, the sliding bearing is driven to move up and down integrally under the action of the shaft, the sliding bearing and the servo motor are connected by the middle support, and the servo motor is pulled to move up and down in the motor guide rail.

The bottom of the piston rod is connected with a thrust bearing through a bracket and a bolt, the thrust bearing consists of two thrust washers and a plurality of rolling bodies, and the rolling bodies are combined into a whole by a copper retainer. A spring is arranged below the thrust bearing, and a load is placed at the lower end of the spring; when the piston rod moves up and down, the piston rod also rotates under the action of the servo motor, when the piston rod pushes the spring to extrude load, the thrust bearing separates the rotation under the action of pressure, the load at the lower end is static, and the piston rod still rotates, wherein the thrust bearing plays a role in separating the movement.

Furthermore, the piston rod and the piston are made of 45 steel.

Furthermore, a check valve with exhaust is installed on the left side of the oil inlet and used for exhausting redundant air in the hydraulic cylinder to balance pressure.

Furthermore, a throttle valve is arranged on the left side of the oil outlet and used for adjusting the pressure and the flow of the hydraulic oil to be required, so that the saved hydraulic oil is returned to one side of the low pressure, and the whole hydraulic oil can flow circularly.

The utility model discloses an effect and benefit are: piston rod and piston are rotatory under servo motor's effect, do not have the drive force that the effect only acted on from top to bottom before comparing, and the stiction between piston and the cylinder body wall can convert sliding friction into, and according to the physical principle that sliding friction is far less than the stiction, can greatly effectively reduce the influence of frictional force, improves the motion accuracy, prolongs the life of pneumatic cylinder.

Drawings

Fig. 1 is a schematic diagram of a partial half throw of a piston rod rotatable friction reducing hydraulic device.

In the figure: 1, a motor guide rail; 2, a servo motor; 3, a bevel pinion; 4, loading; 5, a spring; 6 a thrust bearing; 7, a nut fastening device A; 8, an oil outlet; 9, the inner wall of the cylinder body; 10 plunger seal (type a); 11O-shaped sealing rings; 12 oil inlet; 13 a stem seal; 14 cleaning the ring; 15 a sliding bearing; 16 an integral support; 17 nut fastening means B; 18 a threaded bushing; 19 a throttle valve; 20, a buffer sleeve A; 21 a piston; 22 a buffer sleeve B; 23 a piston rod; 24 one-way valve with exhaust; 25, flanges; 26 large bevel gears.

Fig. 2 is a front view of the piston rod, which is a stepped shaft type structure.

Detailed Description

The following describes the embodiments of the present invention in detail with reference to the drawings and the technical solutions.

As shown in figure 1, the piston rod rotatable type antifriction hydraulic device comprises a motor guide rail 1, a servo motor 2, a bevel pinion 3, a load 4, a spring 5, a thrust bearing 6, a nut fastening device 7, an oil outlet 8, a cylinder inner wall 9, a plunger seal (A type) 10, an O type seal ring 11, an oil inlet 12, a sleeve rod seal 13, a cleaning ring 14, a sliding bearing 15, an integral support 16, a nut fastening device 17, a threaded bushing 18, a throttle valve 19, a buffer sleeve A20, a piston 21, a buffer sleeve 22, a piston rod 23, a check valve 24 with exhaust, a flange 25 and a large bevel gear 26.

The lower part of the piston rod 23 is inserted into the cylinder body through a sliding bush and is connected with the piston 21, and a sealing ring and a buffer bush A20, B22 are sleeved and connected between the lower part of the piston rod 23 and the piston 21; the A-type plunger seal 10 fixedly connects the piston 21 with the inner wall 9 of the cylinder body, so that the piston 21 is subjected to a horizontal constraint force, and the threaded bushing 18 and the buffer sleeves A20 and B22 on the periphery of the piston rod 23 are subjected to a vertical constraint force on the piston 21 and the piston rod 23.

The flange 25 and the piston rod 23 are fixedly connected together by the O-shaped sealing ring 11 and the sleeve rod seal 13; the cleaning ring 14 is positioned above the flange and plays a role in filtering impurities of the hydraulic oil and purifying the hydraulic oil; the right servo motor 2 is fixed on the motor guide rail 1 and can reciprocate up and down; the output end of the servo motor is connected to the pair of engaged helical gears 3 and 26, and the servo motor 2 is driven to rotate the piston rod 23.

The oil inlet 12 is filled with high-energy hydraulic oil, the left side of the oil inlet is provided with a check valve 24 with exhaust, and the purpose of exhausting redundant air in the hydraulic cylinder is achieved, so that the effect of balancing pressure is achieved. The oil outlet 8 is positioned below the cylinder body, low-energy hydraulic oil flows out of the oil outlet, and a throttle valve is arranged on the left side of the oil outlet and aims to adjust the hydraulic oil to the required pressure and flow rate, so that the saved hydraulic oil is conveyed back to the low-pressure side, and the whole hydraulic oil can flow circularly.

The complete set of devices are fastened and connected through the bracket 16, so that the complete set of devices can be definitely cooperated according to labor, and finally, the expected motion control effect is achieved.

The core point of the utility model lies in the slow rotary motion of the piston 21, compared with the previous pure up-and-down reciprocating motion, the static friction between the piston 23 and the cylinder inner wall 9 after the rotary motion can be converted into sliding friction, and the influence of the friction force on the whole experimental equipment can be greatly reduced according to the physical principle that the sliding friction is much smaller than the static friction; especially for the large-diameter hydraulic cylinder, because the contact area between the piston and the inner wall of the cylinder body is larger, the friction force is also larger, and the rotary piston is adopted, so that the constraint of the friction force can be greatly reduced, the influence of noise can be reduced, and a good control effect is achieved; in addition, the rotating speed of the servo motor 2 can be adjusted to change the rotating speed of the piston rod 23, so that the sliding friction can be changed according to the load under different working conditions, and the system has good adaptability.

The above-mentioned embodiments only represent the embodiments of the present invention, but can not be understood as the limitation of the scope of the present invention, and it should be noted that, for those skilled in the art, a plurality of variations and improvements can be made without departing from the concept of the present invention, and all of them belong to the protection scope of the present invention.

Claims

1. A device for reducing static friction influence in a triaxial test is characterized by comprising a motor guide rail (1), a servo motor (2), a small bevel gear (3), a load (4), a spring (5), a thrust bearing (6), a nut fastening device A (7), a loop bar sealing element (13), a cleaning ring (14), a sliding bearing (15), an integral support (16), a threaded bushing (18), a piston (21), a piston rod (23), a flange (25) and a large bevel gear (26);

the integral support (16) is of a frame structure and plays a role in integral support and fixation; the top of the motor guide rail (1) is arranged on the top frame of the integral bracket (16) and is positioned on the right side; the load (4) is placed on the bottom frame of the integrated bracket (16);

the lower part of the piston rod (23) is extended into the cylinder body through a sliding sleeve to be connected with the piston (21), the threaded bushing (18), the buffer sleeve A (20), the piston (21) and the piston rod (23) are an organic whole, and the whole can reciprocate up and down in the cylinder body; the side wall of the piston (21) is tightly contacted with the inner wall (9) of the cylinder body through an A-type plunger seal (10);

the flange (25) is arranged above the cylinder body, is in contact with the piston rod (23) through a loop bar sealing element (13), and fastens the upper half part of the cylinder body; the cleaning ring (14) is positioned above the flange (25); nut fastening devices A (7) which are uniformly distributed are arranged below the cylinder body and fasten the lower end cover and the lower half part of the inner wall (9) of the cylinder body together;

an oil inlet (12) is arranged above the hydraulic cylinder and used for allowing high-energy hydraulic oil to flow into the cylinder body from the outside, and an oil outlet (8) is arranged below the side wall of the cylinder body and communicated with the inner cavity of the cylinder body; the piston (21) and the piston rod (23) are driven to reciprocate up and down by the repeated circulation of the hydraulic oil; a check valve (24) with exhaust is arranged on the left side of the oil inlet (12) and used for exhausting redundant air in the hydraulic cylinder; a throttle valve (19) is arranged on the left side of the oil outlet (8) and used for adjusting the pressure and the flow of the hydraulic oil to be required so as to ensure that the whole hydraulic oil can circularly flow;

a servo motor (2) is arranged on the right side of the hydraulic cylinder, the right side of the servo motor (2) is fixed on a motor guide rail (1), the servo motor (2) can reciprocate up and down along the motor guide rail (1), the lower part of the servo motor (2) is connected with a pair of meshed small helical gears (3) and a large helical gear (26), the large helical gear (26) and the small helical gear (3) are both connected with a piston rod (23) through flat keys, and the rotary driving force of the servo motor (2) is transmitted to the piston rod (23) through the transmission of the motion of the helical gears, so that the piston rod (23) is driven to rotate;

a sliding bearing (15) is arranged above the piston rod (23), the piston rod (23) moves up and down to drive the sliding bearing (15) to move up and down integrally, and the servo motor (2) is pulled to move up and down in the motor guide rail (1);

the bottom of the piston rod (23) is connected with a thrust bearing (6); a spring (5) is arranged below the thrust bearing (6), and a load (4) is placed at the lower end of the spring (5); the piston rod (23) moves up and down and also rotates under the action of the servo motor (2); when the piston rod (23) pushes the spring (5) to press the load (4), under the action of pressure, the thrust bearing (6) can separate the rotary motion, the lower end load (4) is static, and the piston rod (23) still makes the rotary motion, wherein the thrust bearing (6) plays a role in separating the motion.

2. The device for reducing the static friction influence in the triaxial test according to claim 1, wherein the threaded bushing (18), the cushion sleeve, the piston (21) and the piston rod (23) are an organic whole, specifically: a sealing ring and a buffer sleeve A (20) are sleeved and connected between the lower part of the piston rod (23) and the piston (21), and a threaded bushing (18) is fixedly connected to the periphery of the buffer sleeve A (20); the buffer sleeve arranged on the piston rod (23) can enable the piston (21) and the piston rod (23) to be subjected to constraint force in the vertical direction.

3. The device for reducing the influence of static friction in the triaxial test according to claim 1, wherein an O-ring (11) is further disposed between the flange (25) and the piston rod (23).