SU659935A1 - Device for automatic checking of solidifying concrete strength buildup - Google Patents

Description

The goal is achieved by the fact that in the device for automatic control of hardening concrete curing, containing a contracodometer with hermetic vessels, a differentiator and a signal conditioner, the contracodometer is equipped with elastic gauge elements and a mechanotron diffuser equipped with an analog-digital converter , a memory unit, digital-to-analog converters and a summing amplifier, and a signal conditioner with an adjustable voltage source, a comparator, and a counter ohm, and sealed vessels through other manometric elements are connected to a mecha- lamp lamp connected via serially connected analog-digital converter n memory block to the input of digital-analog converters, the output of which is connected to the corresponding input of summing amplifier, the output of which is connected to one of the inputs a comparator, the other input of which is connected to a source of adjustable voltage, and the output of the comparator is connected to a meter.

The drawing shows a block diagram of the device. The scheme includes: two sealed vessels 1 and 2, elastic manometric elements 3 and 4, electronic lamp-mehanotron 5, in the measuring scheme elements 1-5 constitute the sensor-contractometer, analog-digital converter 6, registers 7, 8 and 9, which form a memory block, digital-to-analog converters 10, AND, 12, summing amplifier 13 (elements 6-13 form a differentiator), comparator AND, modulo-15 counter, adjustable source 16 (elements 14-16 constitute the signal conditioner about the readiness of concrete).

The device works as follows. In the process of hardening of concrete between vessels 1 and 2 with concrete and its model, a pressure difference arises, which by means of elastic manometric elements 3, 4 moves the mechnotron 5 gauge, at the output of the measuring (for example, bridge) circuit, an electrical signal X (contraction signal) characterizes concrete strength. The signal X is fed to the input of analog-to-digital converter 6, is converted into digital form, and then recorded in register 7. Each subsequent reading will shift the recorded information from register 7 to 8 and so on. Thus, in the memory block always n adjacent samples of the signal X are stored, using which the numerical differentiation formulas determine the value of the first derivative. Due to the fact that the contraction signal contains half-fluctuations, it is necessary to use an interference-resistant differentiation algorithm (for example, the Longchosh algorithm, which makes it possible to estimate the smoothed value of the derivative).

When applying the Lanczos algorithm, the value of the derivative is estimated by the formula:

to

S -, 4.

G1 --- K

x,

to

2. j.i

where Xi, .-, -the signal of X at the moment of time (t-f a) 7;

Xi - the value of the derivative signal X

at the time of IT; T is the sampling interval; / С - the number of samples of the signal / Y to the left and to the right of the point iT, used in determining the derivative.

In this case, the number of registers in the memory block.

If we define the derivative by seven counts, then the expression given above has the form:

X-

 3 rz-2X -2 --- / -1 1 28

The use of numerical differentiation algorithms implies

arithmetic operations with samples of the signal X, for which they are converted into an analog signal using digital-to-analog converters 10-12 and summed up with the necessary weights and signs using

operational amplifier 13, at the output of which a smoothed value of derivative X is obtained, which can be used to control the process of heat and moisture treatment of concrete. Also signal x

arrives at the input of the comparator 14, to the second input of which comes from the source 16 a signal that characterizes the minimum rate of increase in concrete strength at which it is possible to finish the heat and moisture treatment of concrete. A veton should be considered ready if the condition is satisfied L times, less than or equal to Xmm. The specified condition is implemented at intervals of time T using a comparator 14 and counter 15. Changing L in the counter, you can change the degree of trust in the result. The appearance of the signal “ready at the output of the counter 15 indicates that the concrete has reached the required

strength.

The proposed device makes it possible to increase the accuracy in determining the moment when concrete is ready, and, consequently, to reduce the energy costs of excessive heat and moisture treatment. Besides

Moreover, obtaining a smoothed value of the derivative of the contraction signal allows controlling the rate of hardening of the concrete, which is important, since if the hardening is too fast in concrete, microcracks can occur, reducing the quality of the products.

Claims (2)

1. USSR author's certificate No. 280964, cl. G 01N 33/38, 1969. 2. USSR author's certificate number 267157, cl. G 01N 33/38, 1968. X