RU2394217C2 - Pyrotechnic device for generating impact effects - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: device consists of a hollow case, a pyrotechnic cartridge, a piston and a locking element. The piston of the pyrotechnic device has a tip on which a removable head is fitted through a thread. The locking element if held in the case through a thread and on a slide assembly in the piston. Permissible stress in the case and piston is greater than permissible stress in the locking element.

EFFECT: design of a reusable pyrotechnic device with controlled range of impact effects.

3 cl, 4 dwg, 1 ex

Description

This invention relates to equipment for impact tests and can be used in tests for high-impact impacts of various devices and equipment, as well as various complex systems (for example, spacecraft).

There are many different stands for impact testing, which include devices for creating impact effects. With the help of vibrating electrodynamic stands, stands with falling tables, etc. (Vibrations in technology: Handbook in 6 volumes. M.: Mechanical Engineering, vol. 5. Measurements and tests, edited by MD Genkin 1981, pp. 476-477). Currently, systems based on vibration stands are most used. The requirements for stands providing the necessary impact are quite high, especially when reproducing effects of high intensity, short duration and complex shape. Sometimes, pyrotechnic devices are used to create shock effects in the stands. For example, RF patent No. 224909, where the burst bolt 8X54 serves as a source of impact. In addition to bursting bolts, for example, US patent No. 2..653. 504, class 85-1, there is a fairly large class of pyrotechnic devices that use gases from the combustion of gunpowder to create pressure, with which various connecting elements are moved and / or destroyed. For example, US patents No. 3530759, class 85-1, No. 3111808, class 60-26.1 and several others.

Each of these devices, when triggered, creates a shock of a certain type (with its own amplitude of impact and duration) and can be used as a source of shock for testing.

Closest to the claimed is the "Pusher", according to US patent No. 2575071, class 60-26.1 (prototype). The pusher is made in the form of a bolt with a head and a threaded rod. Slots are made in the head for screwing the pusher into the housing. A through hole is made along the axis of the pusher. A bellows is located inside the cylindrical channel of the housing. The pyro charge is placed inside the rod and is undermined by an electric fuse. A plunger can slide inside the housing. When the pyro charge is detonated, the gases formed stretch the bellows, which pushes the plunger. The stroke of the plunger is determined by the amount of gunpowder and the length of the bellows.

A significant disadvantage of this device when used as a source of shock is that the shock is not regulated and after its operation the bellows remains under pressure for a long time. In addition, such a device is practically disposable (the most critical elements are subject to replacement).

The problem to which the present invention is directed, is the creation of a pyrotechnic device controlled in a wide amplitude-frequency range for the formation of shock effects of the required type.

The solution to this problem is achieved by the fact that the piston of the pyrotechnic device contains a tip on which a detachable hammer is mounted with the help of the thread, while the locking element is fixed in the housing with the help of the thread, and in the piston in a sliding fit, and the permissible stresses in the material of the housing and piston are greater than the permissible stresses in the locking element, while the diameter or material of the locking element is selected by the formula

Where

d is the diameter of the locking element;

D is the inner diameter of the pyrotechnic device;

p is the required gas pressure in the cavity of the pyrotechnic device;

[τ] - allowable shear stresses in the material of the locking element. The proposed device also contains additional squibs, and the squibs themselves are installed in the separator cartridge, the channels of which are connected to the cavity of the pyrotechnic device.

The essence of the invention is illustrated by drawings, where in Fig.1 shows a General view of the device with one squib, in Fig.2 with a separator for installing squibs. Figure 3 shows the stand for impact testing with the pyrotechnics in question, and figure 4 shows a view A of the stand.

The device (figure 1) consists of a housing 1 with a thread 2, a profiled piston 3 with a sealing ring 4, a locking element 5 with a thread 6. The piston 3 ends with a tip 7 with a thread 8 for installing a replaceable hammer 9. There is a cavity 10 in the piston 3, and in the housing 1, the cavity 11 is between the piston 3 and the squib 12. The cable 13 for the electric fuse is connected to the squib. Figure 2 shows a variant of the device in which, instead of one squib, a cassette separator 14 with squib 12 is installed, the channels 15 of which are connected to the cavity 11.

Figure 3 shows the shock stand SPI 6.3480-0, consisting of a waveguide 16, cables 17, strain sensors 18 of the ballistic pendulum 19 with the studied pyrodevice 20, acceleration sensors 21.

Figure 4 shows a view A of the stand, where 22 is the wall of the ballistic pendulum 19, the powder gases 23 generated when the igniter 12 is activated, the end face 24 of the waveguide 16.

The essence of the invention is illustrated as follows. When voltage is applied to the igniter 12, it is triggered, powder gases 23 are formed and the pressure inside the cavities 10, 11 increases. When the critical pressure is reached, the locking element 5 is cut off (the presence of a thread 6 prevents the locking element from falling out), the piston 3 moves until the interchangeable hammer strikes 9 with the test object (for example, the end face 24 of the waveguide 16). A shock wave is transmitted to the test object. The presence of the separator cassette 14 with the squib 12, replacing the locking element with a stronger element, allows you to adjust the pressure inside the cavities 10, 11 and, accordingly, change the maximum speed of impact of the hammer with the obstacle (test object). In this case, the activation of the squibs can be performed both simultaneously and in any sequence. Replacing the strikers (changing materials, shape, mass of the striker) allows you to change the shape of the shock pulse, which extends the functionality of the proposed device (see, for example, Alimov, DD Impact. Propagation of deformation waves in shock systems. / D.D. Alimov , V.K. Manzhosov et al. - M .: Nauka, 1985 .-- 360 s).

After triggering the pyrodevice 20, a gradual decrease in pressure occurs inside the cavities 10, 11 (one sealing ring does not provide absolute tightness of the device). After replacing the igniter 12, the o-ring 4 and the locking element 5, the pyrodevice is ready for reuse.

Consider the procedure for selecting the parameters of the locking element.

As can be seen from figure 1, 4, the calculation of the diameter of the locking element must be carried out on a clean cut. In this case, the pressure force of the powder gases on the piston is distributed at two cutting points.

Let p be the necessary gas pressure in the cavity of the pyrotechnic device that occurs when the pyro cartridge is triggered, D is the internal diameter of the pyrotechnic device, ad is the diameter of the counter element, S ₁ is the cross-sectional area of the pyrodevice, and S ₂ is the cross-sectional area of the counter element

Then the force acting on each of the two cut points,

and the cross-sectional area of the locking element

When cutting, the calculation is carried out according to the permissible tangential stresses [τ]

hence the diameter of the locking element is

Thus, knowing the necessary pressure in the cavity p and choosing the material by the value of [τ], the necessary diameter of the locking element is obtained.

Because the permissible stresses in the housing and piston are greater than the permissible stresses in the locking element, then when the locking element is destroyed, the destruction of the housing and piston will not occur. This makes it possible to reuse the pyrotechnic device.

Practical example

At the enterprise, for the impact testing of devices, the impact stand SPI 6.3480-0 is currently used. The source of shock in this stand is explosive bolts of the 8X54 type, which have an increased value of impact (up to 2 × 10 ⁵ N) and a duration of the order of ~ 0.1 ms, which does not overlap the required range of impacts.

Consider one embodiment of the proposed device, shown in figure 1. and 4.

The diameter is ~ 30, the length is 120 mm, the mass of the device is ~ 100 g. The striker is brass, hemispherical (a “spot” with a diameter of 5.6 mm is made on the hemisphere), and the mass is ~ 35 g. The applied squib cartridge DP4-2.

In the waveguide (3) was obtained pulse close to trapezoidal, ~ 0.5 ms duration with the amplitude of 1.2 × 10 ³ N. It is possible to create the test equipment acceleration up to 1 ms effects with amplitudes in the range 300-1000g.

Of the sources of information and patent materials known to the authors, the totality of features similar to the totality of features of the claimed objects is not known.

Claims (3)

1. A pyrotechnic device for creating impacts, consisting of a hollow body, a squib, a piston, a locking element, characterized in that the piston of the pyrotechnic device contains a tip on which a detachable hammer is mounted using thread, while the locking element is fixed in the housing using thread and in the piston in a sliding fit, and the allowable stresses in the housing and piston are greater than the allowable stresses in the locking element, while the diameter and material of the locking element is selected by the formula

where d is the diameter of the locking element;
D is the inner diameter of the pyrotechnic device;
p is the required gas pressure in the cavity of the pyrotechnic device;
[τ] - allowable shear stresses in the material of the locking element. 2. The device according to claim 1, characterized in that it contains additional squibs. 3. The device according to claim 2, characterized in that the squibs are installed in a separator cartridge, the channels of which are connected to the cavity of the pyrotechnic device.

Images