RU2752378C1 - Servohydraulic testing machine for evaluation of operating characteristics of antiseismic hydraulic shock absorbers of atomic reactors - Google Patents

Abstract

FIELD: testing.

SUBSTANCE: invention relates to tools (testing machines) and methods for studying operational characteristics of antiseismic hydraulic shock absorbers of nuclear power plants and can also be used for mechanical testing of material samples for tension, compression, and low- and high-cycle fatigue with zero crossing. The machine is comprised of a loading apparatus containing a base and a fixed traverse rigidly interconnected by columns, a crossbar rigidly connected with the fixed traverse by columns, a hydraulic cylinder for the ultimate load, installed in the base and rigidly attached thereto, a movable traverse coupled with the columns through antifrictional sleeves and rigidly attached to the plunger of the hydraulic cylinder for the ultimate load, one of two grips for fixing the studied hydraulic shock absorbers, coupled with the movable traverse through a force sensor, a small force hydraulic cylinder installed in the crossbar and rigidly attached thereto and by the plunger of said cylinder through the small force sensor connected with a rod installed in the fixed traverse on a hydrostatic bearing with the second grip, movement sensors. The machine also comprises a pumping unit, a system for control, measurement and processing of the research results. The areas of working cavities of the hydraulic cylinder for the ultimate load differ by a factor of two: the cavity with a larger area is controlled, and in the cavity with a smaller area constant pressure is maintained by means of a pumping unit. A threaded rod is introduced into the structure of the machine, placed inside the plunger of the hydraulic cylinder for the ultimate load with a free fit, rigidly attached at one end to the movable traverse and fastened and unfastened by means of two nuts with the plunger configured to be displaced longitudinally relative to the threaded rod.

EFFECT: provided is possibility of determining the perception of dynamic load by hydraulic shock absorbers with a high frequency of cyclic loading at optimal flow rate of the pumping unit.

2 cl, 1 dwg

Description

A number of machines, both foreign and Russian, are known to test the operational characteristics of antiseismic hydraulic shock absorbers for nuclear reactors. Their advantages and disadvantages are listed in the description of the invention "Hydraulic test machine", patent No. 2535531, which is the closest prototype of the claimed machine and can be taken as an analogue.

The disadvantages of the analog design include:

1. Low hydraulic rigidity of the main power hydraulic cylinder, which does not allow studies of hydraulic shock absorbers (GA) to perceive dynamic loads with a high loading frequency.

2. In the mode of checking the resistance force created by the hydraulic drive at idle, the displacement of the hydraulic stem from one position to another at a low speed is carried out with the help of a small hydraulic cylinder with the cavities of the main hydraulic cylinder locked by hydraulic locks. Such a scheme determines the magnitude of the stroke of the small cylinder not less than the stroke of the stem of the investigated GA and the presence of two hydraulic locks in the scheme.

3. Structurally complex and inconvenient in operation, the clutch for switching on and off from the power circuit of the main hydraulic cylinder, the hydraulic cylinder of small forces and the force sensor.

This introduces additional requirements for the design and quality of the frame, making it more expensive to manufacture.

The claimed machine is devoid of these shortcomings.

The attached figure (Fig. 1) shows the claimed machine, which includes the following units:

- a loading device containing: base 1, stationary traverse 2, rigidly connected to the base by columns 3, power hydraulic cylinder 4, operating at maximum load, with body 5 and plunger 6, having working hydraulic sealed cavities "A" and "B", rigidly fastened to the base by means of a threaded ring 7, a movable traverse 8, mated with the columns 3 through antifriction bushings 9, a force sensor 10 rigidly connected to the traverse by bolts, a threaded rod 11, fastened to the traverse 8 by means of a thread and passing inside the plunger 6, nuts 12 and 13, with the help of which the rod 11 is fastened and unfastened with the plunger 6, the displacement sensor 14 of the plunger 6 relative to the body of the hydraulic cylinder 5, the guide 15, which protects the plunger 6 from rotation relative to the body of the hydraulic cylinder 5, the displacement sensor 16 of the movable cross-arm 8, the grip 17, rigidly fastened to the force sensor 10 by a pin 18, a rod 19, movably coupled in the axial direction with a fixed crosshead 2 through the hydrostatic bearing 20, fastened to the cross-arm 2 by the nut 21, the grip 22, fastened to the rod 19 by a thread, the cross-bar 23, fastened to the cross-arm by 2 columns 24, a short-stroke hydraulic cylinder of small forces 25 with a plunger 26 fixed in the cross-arm by a nut 27, a low force sensor 28 , fastened to the rod 19 with the help of the housing 29 and with the plunger 26 with the pin 30, the displacement sensor 31 of the plunger 26 relative to the cylinder body 25, the guide 32, which protects the plunger 26 from turning, the stop nut 33 with the handle 34, which serves to switch on and off from the power circuit the loading device of the hydraulic cylinder of small forces 25 and the sensor of small forces 28, nuts 35, 36, 37, 38, 39 and 40 for sampling in the power circuit of the hydraulic cylinder 4 the backlash between the fastened parts when the machine is operating in a cyclic mode with a transition through zero, control plate 41, fastened to the body 5 of the hydraulic cylinder 4, and the investigated hydraulic shock absorber 42, fixed in the grippers 17 and 22;

- a pumping unit 43 with a safety valve 44, which ensures the functioning of the loading device;

- servo valve 45, providing the supply of working fluid to the cavity "B" of the power hydraulic cylinder and installed on the distribution plate 41 of the power hydraulic cylinder;

- servovalve 46, providing the supply of working fluid in the cavity of the hydraulic cylinder of low loads 25;

- control system 47, providing test modes of the GA and measurement of test results.

The claimed machine works as follows:

From the high-pressure line of the pumping unit 43, the working fluid is supplied to the inlet of the servovalve 45, which controls the hydraulic cylinder 4, to the inlet of the servovalve 46, which controls the hydraulic cylinder 25, to the cavity "A" of the hydraulic cylinder 4 and to the hydrostatic bearing 20.

In the cavity "A" of the hydraulic cylinder 4, a constant pressure is maintained by means of the valve 44, the cavity "B", in which the area is twice the area of the cavity "A", is controlled by the servo valve 45 according to the "supply-drain" principle. When the pressures in the cavities are equal, the maximum load directed in one direction is created, with the pressure in the cavity "B" close to zero - the maximum load directed in the other direction.

The longitudinal hydraulic rigidity of the hydraulic cylinder 4 is regulated by displacement of the plunger 6 relative to the body 5 and reaches its maximum value with a minimum volume of the working fluid in the cavity "B".

Hydraulic cylinder 25 - short-stroke, double-sided, serving to control the rod 19 when the machine is operating in the mode of determining the resistance forces created by the GA at idle, as well as for checking the sensor of small forces 28.

The hydrostatic bearing 20 serves to remove the frictional forces on the rod 19 when transmitting the force applied by the hydraulic cylinder 4 to the GA and to the small force sensor 28.

The thrust nut 33 has two positions: the extreme right, in which the hydraulic cylinder 25 and the force sensor 28 are disconnected from the power circuit of the loading device by fixing the rod 19 between the thrust nuts 33 and 39, and the extreme left, in which between the hydrostatic bearing housing 20 and the nut 33 a gap of ~ 4 mm for connecting the hydraulic cylinder 25 and the force sensor 28 to the power circuit of the loading device. The thrust nut 33 is rotated in one direction and the other with the help of the handle 34.

Operation of a servo-hydraulic test machine for investigating the operational characteristics of antiseismic hydraulic shock absorbers of nuclear reactors in the mode of determining the resistance force created by the GA at idle at low travel speeds.

Preparatory operations:

- nuts 38 and 39 are fastened together and with a grip 22;

- the rod 19 is displaced by the hydraulic cylinder 25 to the left until the nut 39 stops at the end of the hydrostatic bearing;

- the nut 33 is turned by the handle 34 to the extreme left position, as a result of which a gap of ~ 4 mm is formed between the end face of the nut and the end face of the hydrostatic bearing housing;

- the rod 19 is displaced by the hydraulic cylinder 25 to the right by 2 mm, forming a gap of 2 mm between the nuts 33 and 39 and the hydrostatic bearing housing 20;

- the grip 17 is set by the hydraulic cylinder 4, controlled by the servovalve 45 for movement, in a position corresponding to the distance between the fasteners of the investigated GA. With the required displacement of the gripper 17, greater than the stroke of the plunger 6, to set the gripper 17 to the desired position, the plunger 6's ability to move relative to the rod 11 is used when the nuts 12 and 13 are released.

For example, when shifting towards an increase in the working space, the following operations must be performed:

- the plunger 6 after the displacement of the grip 17 by the amount of travel is in the extreme right position;

- the nut 12 is screwed along the threaded rod 11 by the amount of the plunger stroke 6;

- the plunger 6 is shifted by the servovalve 45 to the left of the stop in the nut 12, while the rod 11 remains stationary;

- the nut 13 is screwed along the threaded rod 11 until it stops at the end of the plunger 6;

- the plunger 6 is shifted by the servovalve 45 to the right together with the threaded rod 11, the traverse 8 and the grip 17 to the required value or until the end of the stroke of the plunger 6, after which the operations are repeated until the grip 17 is set in the desired position.

After installing the required space, the investigated GA is fixed in the grippers 17 and 22 with the middle position of the GA piston;

- the plunger 6 is set by the servovalve 45 in the middle position and is fastened to the rod 11 with nuts 12 and 13.

Work

By the hydraulic cylinder 4, controlled by the servo valve 45 with feedback on the displacement sensor 14, the GA rod moves from one extreme position to another, while the cylinder 25, controlled by the servo valve 46 with feedback on the displacement sensor 31, maintains the position of the grip 22, while maintaining the gaps between the nuts 33 and 39 and the housing of the hydrostatic bearing 20 within 2 mm, and the force sensor 28 will measure the magnitude of the resistance force of the GA at idle.

Upon completion of the study, the cylinder 25 displaces the rod 19 to the stop of the nut 39 in the hydrostatic bearing housing, and the nut 33, turning against the stop in the hydrostatic bearing housing, turns off the cylinder 25 and the force sensor 28 from the power circuit of the loading device.

Operation of a servo-hydraulic test machine for investigating the operational characteristics of antiseismic hydraulic shock absorbers of nuclear reactors in the mode of determining the perception of a dynamic load by the GA with a high frequency of cyclic loading.

Preparatory operations.

- the gripper 17 is set by the cylinder 4 in the position of the minimum working space;

- in grippers 17 and 22, a control sample is fixed, designed for the maximum load of the machine;

- by cylinder 4 a tensile load is applied to the sample, exceeding the maximum one by 10 ... 15%;

- nuts 35, 36, 37, 38, 39 and 21 are tightened, choosing the backlash between the mating parts;

- the sample is unloaded and loaded with a compressive load of the same value;

- tighten the nuts 40 between the base 1 and the traverse 2, choosing the backlash between the columns and the base 1 and the traverse 2;

- the machine is unloaded, the sample is removed, and the investigated HA is installed in the manner described in the previous section;

- with the middle position of the GA rod, the plunger 6, with the nut 12 released, is set to the left position at a distance of no more than 5 ... 10 mm from the stop at the end of the stroke, which provides the maximum longitudinal stiffness in the "B" cavity and, accordingly, the minimum compressibility losses at high the frequency of cyclic loading, after which it is fastened to the rod 11 with nuts 12 and 13;

- hydraulic cylinder 4 displaces the GA rod to the right until it stops and is loaded with a tensile load that is 10 ... 15% higher than the limit, tightens the nut 12, selects the backlash between the plunger 6 and the rod 11, after which the GA rod returns to the middle position.

Work

- dynamic load with a high frequency of cyclic stress is set to the hydraulic shock absorber by cylinder 4, while force sensor 10 and displacement sensor 14 provide signals to the control system for processing and measurement;

- in static loading modes, the claimed machine operates at the middle positions of the GA rod and plunger 6.

The essence of the invention is as follows.

1. In the analogue and other known machines designed to test the hydraulic shock absorbers of nuclear reactors, the stem of the investigated GA and the plunger of the hydraulic power cylinder are rigidly connected to each other and cannot move relative to each other in preparation for the study.

The hydraulic power cylinder for these machines is double-acting with two controlled cavities. With such a design of the hydraulic cylinder, the rigid connection of the GA rod and the plunger of the power hydraulic cylinder is fully justified.

A threaded rod is introduced into the design of the loading device of the inventive machine, placed inside the hydraulic cylinder plunger along a loose fit and rigidly at one end, by means of a thread, connected with a movable crosshead 8, articulated with a force sensor 10 and an active grip 17.

The plunger is fastened to the threaded rod with two nuts at the ends of the plunger and can be displaced relative to the rod when the nuts are released.

In the claimed machine, the hydraulic power cylinder operates according to the differential scheme: constant pressure is maintained in the cavity with a smaller area, and in the controlled cavity, the hydraulic stiffness is regulated by changing the volume of the working fluid, i.e. when the minimum volume is established, the loss on the compressibility of the working fluid is minimized and it becomes possible to determine the perception of the dynamic load by the GA with a high frequency of cyclic loading at the optimal flow rate of the pumping unit, i.e. the machine acquires an additional new function.

2. In the mode of testing the resistance force created by the GA at idle at low travel speeds, the machine operation scheme has been changed (see the section "Machine operation in the mode of determining the resistance force created by the GA at idle at low travel speeds"), which simplified the design , namely:

- the cylinder of low forces has become short-stroke and, accordingly, the displacement sensor, the anti-rotation guide and the hydrostatic bearing rod have decreased;

- there are no two controlled hydraulic locks in the machine diagram;

- the circuit for switching off the loading device of the hydraulic cylinder and the sensor of small forces from the power circuit has been simplified, both structurally and in terms of ease of use.

Claims (1)

Servo-hydraulic testing machine for investigating the operational characteristics of antiseismic hydraulic shock absorbers of nuclear reactors, including a loading device containing a base, a fixed traverse, rigidly interconnected by columns, a crossbar rigidly connected to a fixed traverse by columns, a hydraulic cylinder for maximum load installed at the base and rigidly fastened to it , a movable traverse coupled with the columns through antifriction bushings and rigidly fastened to the hydraulic cylinder plunger for the ultimate load, one of two grips for fixing the investigated hydraulic shock absorbers, fastened to a movable traverse through a force transducer, a low force hydraulic cylinder installed in the cross member and rigidly fastened to it, and its plunger through a small force sensor connected to a rod with a second grip installed in a fixed cross-beam on a hydrostatic bearing, displacement sensors, and also including a pumping unit, a control system, measuring and processing of the research results, characterized in that the areas of the working cavities of the hydraulic cylinder for the maximum load differ by a factor of two: a cavity with a larger area is controlled, and in a cavity with a smaller area, a constant pressure is maintained using a pumping unit, as well as the fact that in the design of the machine includes a threaded rod, placed inside the hydraulic cylinder plunger for the maximum load on a free fit, rigidly fastened with one end to a movable crosshead, and fastened and unfastened using two nuts with a plunger that has the possibility of longitudinal displacement relative to the threaded rod.

Images