RU1777019C - Impact-load test method for objects - Google Patents

Abstract

The invention relates to a test technique. The aim of the invention is to reduce material consumption and improve operating conditions. According to the described method, a piston-striker 3 and an inertial body 4 in the form of a piston are installed in the barrel 2 of the pneumatic stand open on both sides, accelerate them in the opposite # 7 LJ sides by applying pressure to the cavity between them and load the test object 6, mounted on the piston 5, by transferring the kinetic energy of the piston-striker 3 to it. To exclude the transfer of the recoil force to the base 1, the departure time of the body 4 from the barrel 2 should coincide with the moment the piston-striker 3 reaches the windows 13 for gas discharge. The purpose of the invention is achieved by reducing body weight 4. To ensure that the above condition is satisfied, the lack of body weight 4 is compensated for by the action of a force synchronized with the movement of the piston-shock 3 and acting in the opposite direction to the movement of the body 4. A compensating force can be created by reactive thi. 1 s.p. f-ly, 1 ill. (L

Description

„

U

S 6

12

b

,,} 8 / b ZO 17 J5 b s 3

XJ X}

7J 2

R

The invention relates to the field of testing equipment, and in particular, to methods for testing objects under the influence of shock loads implemented in pneumatic shock stands.

Known methods for testing objects under the influence of shock loads are realized when tested in pneumatic shock stands.

A pneumatic stand is known (AS No. 777532) comprising a barrel, two mass pistons installed therein with the possibility of translational movement in opposite directions, connected to the barrel in the area between the masses and pressure. One of the masses serves to the JHGB mouth of the test object. The masses are interconnected by a flexible connection. When compressed gas is supplied into the barrel cavity between the masses, the latter accelerates in opposite directions under the action of the pressure of the compressed gas. The trunk is open on both sides.

At the time of the complete expansion of the flexible coupling, a sharp braking of the masses occurs, during which the kinetic energy of the piston is converted into a shock pulse.

In this stand, a method of testing objects for impact load is implemented, in which the reaction of acceleration of the piston with the object is compensated by the movement of the second mass in the barrel in the opposite direction. The reaction force of the piston acceleration with the test object is practically not transferred to the stand structure (base), since the accelerated masses are connected to the stand base only due to sip friction, which can be chosen insignificant. The stand does not have a power foundation and practically does not move relative to the platform on which it can be freely installed. The disadvantages of the known method are that its use in pneumatic shock stands leads to an increase in their length and to an increase in the consumed energy of the compressed gas, since both pistons are accelerated to the same speed and their masses are comparable.

A device for impact testing of products is known (application No. 4711158/28, a decision to issue a copyright certificate of 10.90; a prototype), comprising a base mounted on the base of a barrel with a shutter, a piston in the barrel for securing the test product, a high pressure chamber, communicated through a quick-acting valve with a pre-piston cavity of the barrel, an additional piston located in the pre-piston cavity of the barrel, and a trap for the piston with the test product. At the end of the acceleration section of the additional piston, windows are made

to vent gas. The barrel shutter is made in the form of a piston.

A disadvantage of the described apparatus for impact testing is its considerable material consumption and operation, which is manifested with an increase in the mass and dimensions of the tested product.

The aim of the invention is to reduce material consumption and improve the operation of pneumatic impact stands.

5 The delivered circuit is achieved due to the fact that in the method of testing objects for shock load, which is installed in an open piston-striker barrel open on both sides of the pneumatic bench, and

0 inertial body in the form of a piston, accelerate the piston-hammer and inertial body in opposite directions by applying pressure to the cavity between them and load the test object with an impact load

5 by transferring the kinetic energy of the accelerated piston-strike to it, and the parameters of the inertial body are selected from the condition of its departure and from the barrel at the moment of acceleration of the piercing-strike to the speed required to reproduce the given shock load, in this method the mass of the inertial body is set to a minimum, determined the requirement of structural strength, and the lack to fulfill the aforementioned

5 conditions, the mass of the inertial body is compensated by the action of a force on it, which is applied in the direction opposite to the movement of this body, and the action of the force is synchronized with the movement

O piston-shock, The force acting on the inertial body is created using reactive thrust,

The drawing shows a diagram of a bench that implements an example of a method of testing objects for impact load.

The stand contains a base 1, mounted on the base open on both sides of the barrel 2, placed in the barrel 2

0 piston-striker 3 and the inertial body 4, made in the form of a piston, and also a piston 5 for the object 6. The stand contains a high-pressure chamber 7 connected by a channel 8 through a valve 9 with a cavity 10 formed in the barrel 2 between the piston-striker 3 and inertial body-piston 4,

In the initial position, the piston 5 is fixed by the holder 11, made in the form of, for example, a destructive element installed in the wall of the barrel 2. To brake and stop the piston 5 after it leaves the barrel 2, a trap 12 is provided. At the end of the acceleration of the piston-hammer 3, windows 13 are made for discharge of gas into the atmosphere.

A hole 14 is provided for communicating the chamber 7 with a pressure source (not shown).

A cavity 15 is made in the inertial body A, and a hole 17 is made in the cover 16, which is sealed in its initial position with a replaceable destructible diaphragm 18.

A hole 19 is provided for the connection of the cavity 15c with a pressure source (not shown). The cavity 15 and the pressure source can be connected by means of a flexible hose-flexible connection (not shown). In the diaphragm 18, radial grooves can be made along which it is destroyed. The parameters of the inertial body 4 are selected from the condition of its departure from the barrel 2 at the time of acceleration of the piston-strike 3 to the speed required to reproduce the given shock load.

A mass 22 is placed in the guide cylinder 20 with a longitudinal groove 21, in which a knife 23 for opening it is mounted on the side of the diaphragm 18, the blade which is set at a certain distance from the plane of the diaphragm 18.

This distance is determined by the opening time of the diaphragm 18 depending on the movements of the piston 4 and 3.,

The mass 22 is equipped with a damping gasket 24 (felt, rubber, etc.). If necessary (in the case of the mass 22 leaving the guide cylinder 20), the stand can be equipped with means 25 for braking this mass, which are made in the form of sequentially placed dampers and masses (similar to trap 12).

The stand works as follows.

The piston-striker 3 is installed in the barrel 2. After that, the piston 5 and the test object 6 are installed in the barrel 2. Then, an inertial body-piston 4 is installed on the opposite side of the barrel 2, the cavity 15 of which is pre-sealed with a diaphragm 18. In the guide cylinder 20, mass 22 with a knife 23, the blade of which is set at a certain (calculated) distance from the plane of the diaphragm 18. A mass of damping gasket 24 is also preliminarily placed on the mass 22. The position of the piston 5 is fixed by the holder 11. From the source pressure through the hole 14, the compressed gas (air) is supplied to the cameo 7. Then the hole 14 is closed. On the pressure source, the compressed gas (air) fills the cavity 15 in the inertial body 4 through the hole 19. Then, the hole 19 is closed. (It is possible to constantly communicate the pressure source 5 with the cavity 15 by means of a flexible connection via a groove 21 in the cylinder 20).

In this state, the test bench is prepared for testing the facility.

0 When valve 9 is activated, compressed air from chamber 7 passes through channel 8 into the piston cavity 10 of barrel 2. The air pressure in it increases. Upon reaching the air pressure in the cavity 10

5 to the piston 3, sufficient to overcome the frictional force of this piston, the latter begins to accelerate, move in the barrel 2 in the direction of the windows 13. In this case, the inertial body-piston 4 moves to

0 to the barrel 2 in the opposite direction to the accelerated piston-striker 3 direction, reducing the effect of the reaction force on the stand structure that occurs when the piston 3 is accelerated.

5 The speed of the piston 3 increases. The compressed air generated in front of the piston 3 is discharged through the windows 13. The piston 5 when the piston 3 moves in the area of the barrel 2 until the windows 13 pass through it

0 remains stationary, as it is fixed by the holder 11. At the moment of passage of the windows 13, the firing pin 3 acquires a maximum speed. After the piston passes through 3 windows 13, it begins to compress

5 the air in the part of the barrel 2 formed by the piston 3 and the piston 5 (in the initial state, the air in the barrel 2 is at atmospheric pressure).

If the air pressure exerted on the piston 5 of a certain size, the holder 11 is destroyed and the piston 5 is released. With further movement of the piston 3, the air pressure on the piston 5 increases and reaches a maximum

5 values at the moment of maximum approximation of pistons 3 and 5.

At this point in time, the peak value of the shock acceleration acting on the object 6 is formed. After the energy exchange occurs between the pistons 3 and 5, the piston 5 acquires a maximum speed. After exiting the barrel 2, the piston 5 is braked by the trap 12 at the braking acceleration level 5 acceptable for the object 6. The trap 12 is made, for example, in the form of dampers and masses freely placed in the guides.

The inertial body-piston 4, moving in the direction of mass 22, acquires a certain speed. Knife 23.

l

ustamovlsps. I do not meoso 22, interacting with the membrane 10, scolds the latter, opening at least 17 (oni -., 1- orifice 17 may be, but in addition to the nozzle). Compressed gas (air). drains from the cavity 15 through the hole 17 into the atmosphere. At the same time, a force was exerted on body 4 by force, counteracting the percussion of this body, which is equivalent to consuming the mass of the inertial body 4.

To reduce the co-force: the active interaction of the body 4 and. mass 22, the latter is equipped with a damping prokpalkoP 9.l,

If, in an experiment, I caught, in which, after loading the object, the heat 4 i will go outside the cylinder 20 and brake 25.

The magnitude of the reactive force and the law of its change in time are determined by the pressure of the gas (air) in the cavity 15, the bore of the hole 17 and the volume of the cavity 15.

Thus, due to the fact that in the method under consideration, the mass of the inertial body is compensated by the action of a force on it, which is applied in the opposite direction to the movement of this body, the action of the force being synchronized with the movement of the piston-striker, and a reduction in the material consumption and an improvement in the operation of pneumatic shock stands.

,, usi 1, {. P-3 i f i

mm ular Formula

Claims (2)

1. A method of testing objects for shock loading, according to which a piston-striker and an inertial body in the form of a piston are installed in an open on both sides of the trunk of the pneumatic stand, the piston-striker and inertial body are accelerated in opposite directions by feeding pressures into the cavity between them and load the test object with an impact load by transferring the kinetic energy of the accelerated piston-shock to it, and the parameters of the inertial body are selected from the condition of its departure from the barrel and the moment of acceleration of the piston-shock to the speed required to reproduce the given shock load, which differs and so that, in order to reduce material consumption and improve operating conditions, the mass of the inertial body is set to the minimum, determined by the requirement of structural strength, and the missing for the condition the inertial gel is compensated by the action of a force on it, which is applied in the opposite direction to the movement of this body, and the action of the force is synchronized with the movement of the piston-striker. 2. A method according to claim 1, characterized in that the force acting on the inertial body is created using reactive thrust.