SU1165896A1 - Method of measuring volume of article inner space - Google Patents

Abstract

A METHOD FOR MEASURING THE VOLUME OF THE INTERNAL CAVITY OF THE PRODUCT by bypassing the gas through a locking device and then measuring the equalized pressure, that is, the pressure. In order to improve the accuracy of measurement, the internal cavity of the product is pre-sealed with a calibrated orifice assembly, filled with gas to a predetermined pressure, and the rate of pressure drop in the internal cavity of the product is measured before the gas bypass; . The moment of reaching the pressure of the bypass is carried out and the bypass is carried out into the calibrated container at the moment of time preceding the moment of reaching the bypass pressure at the time of the closing device actuation. (L O) el 00 UD O)

Description

The invention relates to a measuring technique, and can be used to measure the volume of the internal cavities of products, for example pipes, for their rejection,

There is a known method for measuring the volume by measuring the change in pressure of a gas flowing from a pre-sealed cavity and a gas flow L

However, when using this method, it is necessary to measure two parameters (pressure and gas flow) over time. This introduces large errors in the result of measuring the volume of the cavity, and consequently, in the result of culling products that have cavities, since the measurement error is determined by the sum of the errors | measurement | eui parameters

Closest to the present invention is a volume measurement method. Using this method, from a tank with compressed air, a certain amount of air is passed through to a calibrated tank to a certain pressure. Then bypass

the air from the calibrated tank to the pre-sealed one measured, equalizes the pressure in these tanks and according to the magnitude of the gauge; New pressure in the tanks calculates the volume iz.

A disadvantage of the known method is the low accuracy of measuring the volume of the container of the products, which is caused by the impossibility of achieving a stable gas pressure in the calibrated container. After gas has been bypassed from the compressed air tank into a calibrated tank, it is necessary to cut off the tank from the tank to a certain pressure and then, opening a channel connecting the calibrated tank to the measured one, equalize the gas pressure in these tanks. To perform the operations of closing and opening the channels connecting the tanks, some specific time is required. During this time, the pressure in a calibrated tank, due to gas leakage through leaks, will drop by some value which will depend on the leakage value. For each measurement, this is its own, well-defined value, therefore, take it into account

A correction factor is not possible. Since the known method of pressure drop, due to the fact that the leakage of gas through leakages does not take into account, the measurement error of the volume of the containers is quite large.

The aim of the invention is to improve the measurement accuracy.

This goal is achieved by the fact that, according to the method for measuring the volume of the internal cavity of products by passing gas through a locking device and then measuring the equalized pressure, the internal cavity of the product is preliminary; sealed with a calibrated orifice unit, filled with gas to a predetermined pressure, before the gas bypass, the rate of pressure drop in the internal cavity of the product is measured by extrapolation when the bypass pressure is reached, and the bypass is carried out into the calibrated container at the time preceding the moment of reaching the bypass pressure time of locking the locking device.

FIG. 1 is a diagram of one of the devices that implement the method; in fig. 2 is a diagram explaining his work; in fig. 3 - the scheme of joining the product with the elements of the device.

The device consists of a tank

1 with compressed air, products 2 with an internal cavity, a calibrated container 3, an electropneumatic valve 4 of the locking device 5, a safety valve 6 with a calibrated orifice 7, a contact pressure gauge 8, control devices 9 and 10 of the control, a device 11 for measuring the rate of pressure drop in the internal cavity item 2, pressure drop time counter 12 to transfer pressure with analog computing element 13, sensor

14 times with analog computing element 15, measuring device 16. Internal cavity products

2 is sealed with a help of two steel flanges 17 with rubber gaskets 18. Moreover, one of them has a pipe 19 connecting the cavity with a safety valve 6 with a calibrated orifice 7, and the other has a pipe 20 that connects the internal cavity respectively to the tank 1 and a calibrated container 3. The volume of the internal cavity is measured as follows. The product is joined to the sealing assembly and the device elements according to the scheme in FIG. 3. Via electropneumatic valve 4, compressed air is fed from tank 1 into the internal cavity of product 2, while the gas pressure in it begins to increase (Fig. 2, section 28-21). In this area, gas escapes from the cavity only through the existing -:. Densities in the sealing units. When a certain pressure is reached (point 21 in Fig. 2), the safety valve 6 is activated and the air begins to flow from the cavity out through the calibrated orifice 7. The cross section of the hole 7 is adjusted so that the gas leaks would be constant in time. For this, gas is injected into the internal cavity of product 2 to a pressure such that in section 23-26 of the gas outflow process diagram is supercritical. Moreover, the amount of gas flowing through the calibrated orifice 7 exceeds the amount of gas flowing through all leaks in the sealing units. When a certain pressure is reached (point 22 in Fig. 2), the supply of air is stopped (from the contact manometer 8, through the command device 9, the command to close the electrofluid air valve 4 is given). During the operation time of the electropneumatic valve 4, the pressure in the cavity will increase by a certain amount (section 22-23 in Fig. 2). For: each measurement is determined by a value depending on the gas pressure in tank 1 and the leakage in the sealing units. After the electropneumatic valve 4 is closed, the pressure in the cavity gradually decreases due to gas leakage (section 23-26, fig. 2). At the same time, the gas outflow is very supercritical. When a certain control pressure is reached (point 24 in fig. 2) the rate of gas pressure drop in the internal cavity of product 2 (a logical coincidence circuit is triggered at the inlet-device 1.1 for measuring the pressure drop rate CJ). Next, using the measured pressure drop rate, the moment of reaching the bypass pressure (point 26 in Fig. 2) is determined by extrapolation (signal 26 from the device 11) to the time counter 12 with the analog computing element 13). The response time of the locking devices 58i is constant and known. Therefore, after determining the pressure drop from a predetermined value to a predetermined bypass pressure, the analog computing element 15 of time sensor 14 is determined. the time for the opening command of the locking device 5. The opening command is given by the command device 10. During the response time of the locking device 5, the pressure in the cavity drops by some value SP (section 25-26 in Fig. 2) and reaches the required selected value P. Therefore, the transfer of gas from the internal cavity of the product 2 into the calibrated container 3 occurs strictly at the selected value of the bypass pressure (point 26 in Fig. 2), regardless of the size of the leaks. Then, the volume of the cavity is determined from the value of the equalized pressure (point 27 in Fig. 2) using a measuring instrument 16, the scale of which is calibrated so as to reject the product. The proposed method is simple in EX. it has a higher accuracy than the one known for measuring the volume of the inner cavity of products.

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Fig 3

Claims (1)

METHOD FOR MEASURING THE VOLUME OF THE INTERNAL CAVITY OF A PRODUCT by passing gas through a locking device followed by measuring the equalized pressure, characterized in that, in order to increase the accuracy of the measurement, the internal cavity of the product is pre-sealed with a calibrated orifice, filled with gas to a predetermined pressure, and the speed is measured before gas bypass the pressure drop in the internal cavity of the product is determined by extrapolating the moment when the bypass pressure is reached, and the bypass is carried out in a calibrated volume spine in the time preceding the pressure reached at the time of bypass during switching of the lock. Figure 1 Od SP oo so ABOUT)