RU2251229C2 - Laser centralizer for x-ray emitter - Google Patents

Abstract

FIELD: nondestructive tests of equipment using roentgen rays.

SUBSTANCE: proposed device has laser, reflector mounted on intersection point of laser and X-ray beams, and means for displaying distance between X-ray emitter and equipment under test. This device is characterized in that it has second reflector coupled with display means indicator and mounted past second end of laser on laser axis and perpendicular to plane formed by laser and X-ray beam axes at constant angle to laser axis for translational movement along this axis.

EFFECT: enhanced measurement accuracy and human factor.

2 cl, 2 dwg

Description

The invention relates to non-destructive testing of materials and products using x-ray radiation and can be used to control objects of aerospace engineering and other engineering industries by the radiation method.

A known laser centralizer having a housing in which there is a laser with a two-sided output of radiation, the optical axis of the output of which is parallel to the longitudinal axis of the x-ray emitter, two reflectors, the first of which is made of plexiglass and is installed at the intersection of the optical axis of the laser with the axis of the x-ray beam of the emitter, and the second is mounted with the possibility of rotation around an axis parallel to the axis of rotation of the first reflector on the axis of the output of laser radiation I, a means of indicating the distance from the x-ray emitter to the object and means of interrupting the beam from the second reflector, installed before or after the second reflector, the centralizer is additionally equipped with two cylindrical lenses mounted on the axis of the laser radiation, the first between one of the highlander of the laser reflector and the first reflector, and the second is between the second end of the laser emitter and the second reflector, their focal length is selected from the relation f = h / tgα, where h is the radius of the laser beam, α is the angle of the x-ray radiation beam, while the lenses are mounted to rotate around the axis of the laser beam [1].

The disadvantage of this device is the low accuracy of measuring the distance from the object to the emitter at distances of the order of 3000-5000 m, which is typical for the control of large-sized objects of aerospace engineering. In this case, to ensure the required measurement accuracy, the distance error (of the order of ± 30 mm), the reading error on the scale of the indicator of these distances is in angular measure L = (1-3) angular minutes even at the maximum permissible due to design limitations of the size of the centralizer rangefinder base of the order of B ≤ 300 mm, B is the distance between the reflectors along the laser axis. The linear division size of the indicator scale corresponding to these angles is t≤ 0.1 mm even when the diameter of the scale is D = 2R≈ 200 mm, which follows from the obvious equation t = R · α = 100 · 10 ^-3 = 0.1 mm ( α = 3 '= 0.001 in radian measure). This circumstance, in turn, leads to unreasonably high requirements and the corresponding means of reference on a scale, which affects the technical and economic performance of the device. In addition, the scale is non-linear, because the distance between its strokes is proportional to the tangent of the angle of inclination to the laser axis of the beam reflected from the second reflector.

However, when the scheme for reflecting rays from the second reflector used in the centralizer, its rotation through the angle α leads to a deviation of the reflected beam from the original direction by the angle 2α, which further reduces the angular size of the working range of the scale and the linear size of its divisions, reduces the accuracy of measurements and worsens operational and ergonomic characteristics of the centralizer as a whole.

The use of cylindrical lenses in the centralizer, forming two light strips on the object, whose angular size in the image space corresponds to the radiation angle of the x-ray emitter, is not always rational, because usually it’s enough to highlight a luminous point on the object corresponding to the point of its intersection with the axis of the x-ray beam. In this case, the region of the object that is illuminated by the x-ray beam is determined by the size of the cassette with the film superimposed on it during radiography.

, а цена минимального деления шкалы tmin в пространстве объектов равна to=t_min · tgα .To eliminate the above drawbacks, the second reflector is stopped on the optical axis of the laser behind its second end perpendicular to the plane formed by the axes of the x-ray and laser beams at a constant angle α to the laser axis with the possibility of translational movement along the laser axis, the scale is linear and corresponds to the equation L = x · tgα, where x is the linear displacement of the second reflector along the laser axis, L is the distance from the x-ray emitter to the object tgα = const, while the division of the scale corresponding to the minimum Lmin and ootvetstvenno maximum distance Lmax from the object to the X-ray emitter, located at a distance from the axis of the laser beam along the x-axis equal to Xmin = Lmin · tgα and Xmax = Lmax · tgα, scale length corresponding to the working range of distances from the object to the X-ray emitter is

, and the price of the minimum division of the scale tmin in the space of objects is equal to = t _min · tgα.

.The construction of the scale at tgα = 10 is especially convenient. In this case, standard linear centric scales (GOST 427-75) with a minimum division value of tmin = 1 mm, digitized after 10 mm are used, the price of this division in the space of objects is equal to = tmin · 10 = 10 mm, which is quite enough for the practice of radiation monitoring . The distance or the axis of the x-ray beam to the scale division corresponding to the minimum distance from the object to the x-ray emitter is equal to Xmin = Lmin / 10 = 0.1 Lmin, the distance corresponding to the maximum distance of the object from the x-ray emitter is Lmax = Lmmax / 10 = 0.1 Lmax, and the scale length is

.

To determine the current distance from the object to the x-ray emitter, it is enough to count on a scale equal to X (cm), multiply by ten, i.e. L = 10 × (cm). It is clear that the initial portion of the scale (Xo≤ Xmin) is thus removed so that it does not shield the x-ray beam.

The magnitude of this deleted portion of the standard scale is determined from the obvious relation Xo≥ N · tg (β / 2), where β is the angle of the x-ray beam, H is the distance from the focus of the x-ray emitter to the first reflector

The invention is illustrated in figures 1 and 2, which shows the General diagram of the centralizer and the layout of the scale.

The centralizer contains an x-ray publisher 1, to which the housing 2 is mounted with a laser 3 located in it with a two-sided output of radiation, the axis of which is parallel to the longitudinal axis of the x-ray emitter, plexiglass reflector 4 located at the intersection of the x-ray and laser beam axes, the second reflector 5, stopped at the axis of the laser behind its second emitting highlander at a constant angle α to this axis and capable of translational movement along it a linear scale 7, digitized, for example, through 1 cm, pointer 6, h mounted on the second reflector 5 to take readings on a scale of 7, directly proportional to the distance from the emitter 1 to the object 8.

Figure 1 shows the extreme positions of the second reflector 5 (1 and 2), corresponding to the minimum and maximum distance of the object 8 from the emitter 1.

Laser centralizer operates as follows. The laser 3 using the reflector 4 forms a bright dot on the object 8, corresponding to the point of its intersection of the surface with the axis of the x-ray beam.

The radiation from the second end of the laser using the second reflector 5, mounted perpendicular to the plane formed by the axes of the x-ray emitter and the laser, at a constant angle α to the axis of the laser, is also directed to the object 8, forming a second bright point on its surface. Moving the second reflector 5 along the axis of the laser, combine the images of both laser spots and at this moment take a scale equal to the corresponding number of divisions N of scale 7 on a scale 7 using pointer 6 and, multiplying this number by a constant equal to tgα = const, determine the distance from object to the emitter L = tmin · N · tgα.

At tgα = 10 (α = 84 ° 1.8) ’, linear decimal metric scales are used, for example, according to GOST 427-75, with a division price tmin = 1.0 mm, digitized after 10 mm.

For example, if the reading on the scale is equal to X = N · tmin = 105 mm (see Fig. 2), then the distance to the object with tgα = 10 will be L = 105 · 10 = 1050 mm.

The error in measuring the distance from the object to the emitter is determined by the error of the scale, i.e. at the cost of its minimum division, with the proposed measurement scheme it is determined by the quantity Δ L = tmin · tgα and with tgα = 10Δ L = 10tmin, i.e. for standard metric scales with tmin = 1.0 mm Δ L = 10 tmin = 10 mm, which is quite enough for practice. The total error of measuring the distance from the object to the emitter, determined, in addition to the scale division value 7, the error of combining laser points on the object (Δ Lс) and the error due to the non-parallel movements of the second reflector 5 along the laser axis (Δ Ln) can be estimated to a first approximation by the sum of these errors, i.e. Δ LΣ = Δ Lm + Δ Lc + Δ Ln.

For a real prototype of the centralizer, Δ Lm = 10.0 mm, Δ Lc = 1 mm, Δ Ln≈ 1 mm, i.e. Δ LΣ ≈ 12 mm, which fully meets the requirements of practice.

Literature:

1. Patent of the Russian Federation No. 2106619. Laser centralizer.

2. Bronstein I.N., Semendyaev K.A. Math reference. M., Science, 1957, 608 pp.

Claims (2)

1. A laser centralizer for an x-ray emitter, comprising a housing with a laser located therein with a two-sided cure output, the axis of which is parallel to the longitudinal axis of the x-ray emitter, plexiglass reflector mounted at the intersection of the laser and x-ray emitter axes, a shutter for blocking radiation from the second end of the laser, means for indicating the distance from the object to the x-ray emitter in the form of a pointer with a scale mounted on the centralizer body, characterized in that the second reflector is installed it is aligned on the laser axis behind its second radiating end perpendicular to the plane formed by the axes of the laser and the x-ray beam at a constant angle α to the laser axis with the possibility of translational movement along this axis, the scale is linear, uniform, corresponds to the equation L = X · tgα = N · t _min · tgα, wherein X - of the second position of the reflector relative to the scale, L - distance between the object and the X-ray emitter, N - the number of scale divisions corresponding to the position of the pointer movement of the second reflector, t _min - scale value, tgα = const, wherein ₀ - distance from the first reflector before the start of the laser axis scale, X ₀ ≥ H · tg (β / 2), where h - distance from the focus x-ray emitter to the center of the first reflector, β - the angle of the x-ray beam radiation. 2. The laser centralizer according to claim 1, characterized in that tgα = 10.0 is accepted, and the scale is linear, uniform and decimal.

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