SU485368A1 - Radiometric flaw detector - Google Patents

Description

(54) RADIOMETRIC DEFECTIVE

one

A radiometric flaw detector for monitoring products with variable thickness is known, including a radiation source, a scanning device, a radiation detector connected via a divider to a power source, a power source, two amplifiers connected to the output of the radiation detector, an integral discriminator, an integrating cell, a relay unit, a rectifier with smoothing filter and amplifier

but no current.

Such a device makes it possible to compensate to some extent for a change in the KOHTpoinipyeMoro product profile. However, when rolling products with large thickness differences, full compensation cannot be achieved. This occurs because a rectifier requires some imbalance of the circuit and the more compensating voltage that must be applied to the radiation detector, the greater the imbalance of the circuit is needed. The well-known device is static and has a static error.

With large differences in the thickness of the monitored product, the static error will exceed in amplitude the signal of the defect, which causes a false response of the relay. This leads to the need for manual adjustment of the operating mode of the device and additional time costs when monitoring items of complex shape, as well as when switching from one type of product to another type of product with excellent dimensions.

The aim of the invention is to automate the monitoring process by reducing the time for restructuring the operation of a radiometric flaw detector while monitoring complex products.

This is achieved by inserting an inverting amplifier into the device, to the input of which a part of the sensing signal is fed, and an adder in which the output signal of the inverting device is transferred to the recording device. The gain of the inverting amplifier is chosen such that the output voltage of the amplifier is equal in magnitude and opposite in sign to the magnitude of static error at the input of the adder unit. Thus, the signal supplied from the output of the adder is not registered with the device, does not contain a static error. The drawing shows a diagram of the described radiometric flaw detector for monitoring defects in products with a large thickness difference.

The flaw detector consists of a source of radiation 1, (also controlled product 2 is shown), a scintillation detector 3 with a photomultiplier I (PMT) and a voltage divider to power the PMT, integrate the cells 4 with a small time constant, buffer amplifier 5, an adder unit b, a recording device 7, an inverting amplifier 8, an integrating cell 9 with a large time constant, and an etched high voltage power unit 10.

The radiation source 1 is located on one side of the product 2, on the other side of the product there is a skintill diode detector 3c with a photomultiplier and a divider. The output signal from the scintillation detector 3 is fed to the integrating cell 4 with a small posy time, I, from where it is fed to the buffer amplifier 5 and the block of the adder 6. The output of the block of the adder 6 is connected to a registering device 7, which contains threshold stages for outputting a signal defect presence and recording device The output signal of the buffer amplifier 5 is fed to the integrating cell 9 with a long time constant, from where it is fed to a controllable TO block of the high-frequency power and through an inverting amplifier 8 to the input d block adder 6, divider photomultiplier 11ita1X; the voltage supplied from the control unit of the power supply unit voltage switch.

When inspecting a product at a site with a constant thickness, the flaw detector circuit is in the setting mode. If the product has a defect, the density of the radiation detected by the detector 3 changes dramatically. This leads to a sharp change in the signal at the PM output. The voltage on the integrating cell 4 varies with a small time constant according to the change in the radiation flux density. The voltage on the integrating cell is 9 with a large constant. time does not have time to change and the signal about the defect is output to the recording device 7.

With a smooth change in the thickness of the product, the voltage on the integrating cell changes with a large time constant in accordance with the change in signal. This leads to a change in voltage.

power of the PMT and partial compensation of changes in the signal input to the recording device. The signal from the output of the integrating cell 4 with a small time constant is added in

the adder 6 with the inverted signal of the integrating cell 9 with a large time constant, and since the gain of the inverting amplifier 8 is chosen so that these signals are equal, the signal at the input of the register 1: its device 7 will be equal to zero.

With an abrupt change in the thickness of the product, similar compensation is achieved through the adjustment time, which is determined by the time constant of the integrating cell with a large time constant.

Subject invention

A radiometric flaw detector for monitoring products with variable thickness, containing a radiation source, a detector with an adjustable power supply unit and a regimentation circuit consisting of two integrated cells with different constant time, a buffer amplifier and an indication-Jura, characterized in that In order to automate the process of control, it contains an inverting amplifier, rDaKJno4eHHbm to an integrating cell with a longer time constant, and an adder, the inputs are connected to an inverting amplifier and integrating cell this time, and the output - with indica.